The researchers developed the analysis as a deterministic counterfactual. All fixtures, home venues and team travel demands remained fixed while the assigned transport mode changed under explicit rules. The reference scenario, called S0, assigned travel to a coach when the stadium-to-stadium road distance was 300 km or less and to air when it was longer. That rule sent 24 of the 480 legs to coach and 456 to air, producing 12 all-coach and 228 all-air round trips. Two substitution scenarios then replaced reference air legs with direct G-, D- or C-series rail services when a verified no-transfer train had a minimum scheduled duration of no more than six hours in S1 or eight hours in S2. Access and waiting time were not included in these thresholds.

The six-hour scenario assigned 196 legs to rail, 24 to coach and 260 to air. It yielded 98 all-rail, 12 all-coach and 130 all-air round trips, with total emissions of 1,621.07 tonnes. Relative to S0, that was 478.99 tonnes, or 22.81%, lower. The eight-hour scenario added 36 eligible rail legs and 141.35 tonnes of further modeled savings. It contained 115 all-rail round trips, two mixed rail-air itineraries, 12 all-coach trips and 111 all-air trips. The mixed cases demonstrate why the investigators evaluated outbound and return travel separately: a rail service may qualify in one direction while the opposite direction remains eligible for air travel.

Travel options were assembled from 93 city pairs in both directions, producing 186 directional railway queries. China Railway 12306 searches used 20 September 2026 as a common reference date, with information captured on 10 and 11 September. Among the queries, 125 yielded a verified single-train minimum, 52 returned no result within the documented search scope, six showed only ordinary services, two contained only same-vehicle continuation schemes and one minimum remained unconfirmed. The two same-vehicle-only minima, 716 and 749 minutes, exceeded both rail screens. The unconfirmed Beijing–Tianjin minimum did not affect the reported results because coach travel remained the priority for those legs under every tested distance threshold.

For each eligible query, the model minimized scheduled time among trains that did not require a change of vehicle. Where shortest-duration services were tied, selection favored the combination with the smaller total of outbound and return road access, followed by earlier departure and train identifier. Stadium, station and airport access was calculated with the OSRM driving service, which returned a 69-by-69 matrix containing 362 directed road segments used in the analysis. Great-circle distances were calculated from independently sourced OpenStreetMap coordinates. Rail line-haul distance was approximated as 1.10 times stadium-to-stadium great-circle distance, while aviation used great-circle distance without a multiplier. These proxies simplify physical paths and do not reconstruct exact station-to-station rail mileage.

The base accounting assigned carbon dioxide intensities of 0.0326 kilograms per passenger-kilometer to coach travel, 0.0102 to rail and 0.0972 to air. The rail factor originated from 2019 Beijing–Shanghai high-speed rail data and was transferred across the modeled G, D and C services as a common-factor assumption. These values allocate average passenger emissions; they do not measure the fuel consumption of an individual team charter, the marginal emissions of adding 40 people to a scheduled service, or the emissions avoided if a flight or train were canceled. The system boundary covered intercity movement and road access to stations and airports, but excluded supporters, accommodation, food, stadium energy, freight, infrastructure construction, induced demand and aviation effects other than carbon dioxide.

Savings were concentrated among a small group of clubs under the eight-hour scenario. Beijing Guoan had the largest modeled reduction at 64.20 tonnes, followed by Shenzhen Peng City at 62.48 tonnes, Wuhan Three Towns at 60.78 tonnes, Henan at 56.15 tonnes and Zhejiang at 51.51 tonnes. Together, those five clubs accounted for 47.57% of the scenario’s league-wide savings. Wuhan Three Towns had the highest percentage reduction among clubs, at 55.04%, while Shenzhen Peng City’s away trip to Beijing Guoan produced the largest single-fixture difference, 13.46 tonnes or 88.10% of its reference emissions. By contrast, Yunnan Yukun had the highest reference emissions but no leg qualified for rail substitution, illustrating how geographic exposure differed from operational opportunity.

Deterministic sensitivity tests showed that the modeled percentage savings were not confined to a narrow set of assumptions. Across 36 combinations of party size, coach threshold, aviation factor and rail-time screen, S1 savings ranged from 22.35% to 23.79%, while S2 savings ranged from 29.11% to 30.76%. These ranges are not confidence intervals because the complete modeled season was analyzed under fixed rules rather than sampled from a statistical population. Rail-distance multipliers from 1.05 to 1.50 produced S1 savings of 21.74% to 22.94% and S2 savings of 28.15% to 29.71%. Halving or doubling the rail factor expanded the respective S1 range to 19.86%–24.28% and the S2 range to 25.72%–31.45%.

An additional illustration assumed that each eligible itinerary had a uniform 50% chance of being adopted, with the reference journey used otherwise. Under that assumption, expected S1 emissions were 1,860.57 tonnes, representing savings of 239.49 tonnes or 11.40% against S0. Expected S2 emissions were 1,789.89 tonnes, corresponding to savings of 310.17 tonnes or 14.77%. The adoption rate was an assumption, not an estimate of existing rail use or a behavioral forecast, and selective uptake could distribute the effects differently. Overall, the framework offers clubs a transparent way to identify candidate rail journeys, but its thresholds are screening tools rather than proof of door-to-door feasibility. A qualifying scheduled train says little by itself about baggage, security, seat availability, disruption, athlete recovery or compatibility with kick-off times, leaving verified travel records and operational pilots as necessary next steps.

Subject of Research: Scenario modeling of high-speed rail substitution for Chinese Super League team travel

Article Title: Direct high-speed rail substitution for Chinese Super League team travel: a directional carbon dioxide scenario assessment

Article References: Yin, Z., Zhang, Y., Li, H., Feng, C., & Xiao, H. (2026). Direct high-speed rail substitution for Chinese Super League team travel: a directional carbon dioxide scenario assessment. Frontiers in Environmental Science, 14, Article 1963916. https://doi.org/10.3389/fenvs.2026.1963916

Image Credits: AI Generated

DOI: 10.3389/fenvs.2026.1963916

Keywords: Chinese Super League, high-speed rail, team travel, carbon dioxide, transport emissions, route-level modeling, counterfactual analysis, rail substitution, professional football, Direct, high-speed, rail

Researchers randomly assigned 30 urban clusters to either targeted indoor residual spraying, or TIRS, or to standard vector-control activities conducted by Peru’s Ministry of Health. TIRS used pirimiphos-methyl and focused on locations where A. aegypti were known to rest inside homes. The intervention covered 15 clusters containing 898 structures, and the comparison group included 15 clusters with 1,018 structures. By examining both sprayed houses and untreated houses in intervention clusters, the investigators could estimate direct effects in treated structures and indirect community-wide effects associated with the intervention.

The team assessed indoor mosquito density using Prokopack aspiration during the 45 days before spraying and at four subsequent time points extending to 255 days after the intervention. Generalized linear mixed models with a negative-binomial link estimated incidence rate ratios, and efficacy was calculated as one minus the incidence rate ratio. These measurements concern mosquito abundance, not human infections. The trial therefore provides entomological evidence about the effectiveness of TIRS but does not establish whether the intervention reduced dengue incidence, other viral infections or disease severity.

The largest direct effect appeared 15 days after spraying, when A. aegypti captures in treated houses were 96% lower than in the comparison group. The estimated reduction then weakened but remained significant at 255 days, when direct efficacy was 40%. In untreated houses located within TIRS clusters, estimated indirect efficacy reached 69% at 15 days. Although this estimate declined substantially over time, it remained statistically significant after eight months, reaching 7% at 255 days. Thus, the results indicate that TIRS was associated with reductions both in sprayed structures and in nearby untreated homes, with a much stronger and more persistent direct effect than indirect effect.

Household-level TIRS coverage was only 57%, yet statistically significant direct and indirect impacts were observed during the early post-intervention surveys, and indirect effects were still evident after eight months. The findings show that partial household coverage can coincide with meaningful reductions in indoor mosquito density. The trial’s scope also constrains interpretation: it was conducted in an urban setting in Iquitos, used one insecticide-based intervention and measured entomological outcomes rather than clinical disease. Within those limits, the results support the entomological value of TIRS in dengue-endemic urban settings and in tropical or subtropical military locations where the method is deployed, without demonstrating a corresponding reduction in human viral transmission.

Subject of Research: Entomological efficacy of targeted indoor residual spraying against Aedes aegypti in Iquitos, Peru

Article Title: Direct and indirect entomological efficacy of Targeted Indoor Residual Spraying against Aedes aegypti in Iquitos, Peru

Article References: Astete, H., Vasquez, G. M., López-Sifuentes, V. M., Zambrano, B., Reyna, B., Moore, R. C., Morrison, A. C., Vazquez-Prokopec, G. M., & Larson, R. T. (2026). Direct and indirect entomological efficacy of Targeted Indoor Residual Spraying against Aedes aegypti in Iquitos, Peru. PLOS Neglected Tropical Diseases, 20(10), e0014390. https://doi.org/10.1371/journal.pntd.0014390

Image Credits: AI Generated

DOI: 10.1371/journal.pntd.0014390

Keywords: Aedes aegypti, dengue, mosquito control, indoor residual spraying, pirimiphos-methyl, cluster-randomized trial, Peru, vector control, entomological efficacy, Direct, indirect, entomological

The research did not use a separate optical-character-recognition system. Each model received an anonymized image containing a student response together with an instructor-approved rubric, then returned every rubric decision in a single structured JSON response. The instruction required a binary award or withholding of credit for each criterion, or null when the model could not determine the answer, with no free-form explanation. This direct image-to-decision design removes an explicit transcript stage and allows a model to use handwriting, mathematical expressions, diagrams or code alongside the grading rules. It also makes errors harder to diagnose: an incorrect result may arise from misreading a symbol, misunderstanding the mathematical reasoning, misapplying a criterion or diverging from the instructor’s judgment. Because transcription accuracy was not independently annotated, the study could measure final image-to-decision performance but could not separate visual recognition errors from reasoning or rubric-application errors.

The study had two stages. In the rubric-generation experiment, Gemini 2.5 Flash produced 922 candidate analytic criteria from 143 problems, including 44 procedural–deterministic, 48 conceptual–deterministic, 27 constructive–structured, 22 reasoning–justification and only two design–open problems. Three faculty members from mathematics, computer science and computer engineering assessed each criterion for immediate usability and each problem-level rubric for completeness. The mean criterion-level satisfactory score was 0.782, while mean problem-level completeness was 0.708. These measures had different anchors and units of analysis, so they were not directly compared. Examples of instructor refinement showed that generated criteria could contain incorrect expected answers, omit acceptable methods or become unnecessarily restrictive. The results therefore treated rubric review as a substantive stage in which instructors retained, revised, expanded, removed or added criteria, rather than allowing generated rubrics to be applied without modification.

For the grading experiment, instructors used the original questions and human-authored rubrics as references, then created final rubrics containing 57 binary items across 31 question units in Calculus, Data Structures and Discrete Mathematics. The criteria were classified retrospectively as structural, correctness, constraint, method or process, and gatekeeping checks; the questions were similarly classified from procedural–deterministic through design–open. One researcher performed these classifications, and no inter-coder reliability estimate was available. They describe the sampled material rather than established general effects of question or rubric type. The experiment also lacked a matched condition using an undecomposed or holistic rubric prompt. The study could therefore evaluate reliability under rubric decomposition and constrained prompting, but could not determine whether either feature caused an improvement over ordinary free-form scoring.

Across all 3,346 rubric decisions, individual agreement with instructors ranged from 76.5% for GPT-4.1 to 87.6% for Gemini 2.5 Pro, with Claude Sonnet 4.6 at 80.5%. A full-coverage majority rule reached 83.7%, below Gemini’s result. Unanswered outputs were treated as zero for these full-coverage comparisons, with complete-case and other null-handling analyses used as sensitivity checks. Cluster-bootstrap intervals were also reported for the nested design, but the 3,346 decisions came from only 31 question units and 11 assessment sets. The figures therefore describe this educational sample rather than providing population-level estimates from 3,346 independent observations. Question-cluster bootstrap intervals for GPT-4.1, Gemini, Claude and majority agreement were 72.2%–80.9%, 84.3%–90.7%, 75.6%–84.9% and 79.2%–87.7%, respectively.

Selective routing separated agreement levels, although the accepted and referred figures use different denominators and should not be read as evidence that consensus outperformed every full-coverage model. Of 2,195 decisions accepted by complete three-model unanimity, 91.9% matched the instructor, an 8.1% discrepancy rate. Among the 1,151 decisions referred for review, a retrospectively calculated majority rule matched the instructor on 68.0%. Of the referrals, 888 had complete outputs with binary disagreement, 245 contained nulls without an observed conflict, and 18 contained both. Gemini agreed with instructors on 95.9% of the 245 null-only cases, compared with 74.8% of complete-output disagreements, indicating that missing output and substantive conflict were distinct sources of referral. Consensus was thus most useful as a mechanism for selecting cases for review, not as a calibrated probability that an accepted decision was correct.

Performance varied substantially among courses. Calculus had 66.0% decision coverage and 94.9% agreement within its accepted subset, while Data Structures had 57.9% coverage and 88.5% accepted agreement. Discrete Mathematics produced no missing outputs, giving it 84.1% coverage, but its accepted decisions agreed with the instructor on only 85.9%. The errors in that accepted subset were directional: models awarded credit in 14.1% of cases where the instructor withheld it, with no corresponding withhold discrepancy. A particularly revealing criterion required a valid symmetry justification in one six-part group assignment. Claude and GPT awarded it in all 31 responses, although the instructor awarded it in eight; Gemini matched the instructor in 13 of 31. Unanimity retained 24 responses, including 17 awards that contradicted the instructor, producing just 29.2% agreement on that criterion. The binary outputs could not establish whether these discrepancies arose from image reading, interpretation of the justification, rubric application or instructor judgment.

At the response level, all required criteria were acceptance-eligible in 60.9% of the 1,875 submission-question records: 63.7% in Calculus, 43.2% in Data Structures and 74.2% in Discrete Mathematics. The unit of review mattered: only nine of 31 complete six-part assignments in Discrete Mathematics passed without any referred criterion, even though 74.2% of their individual parts did. These proportions indicate where a workflow could direct instructor attention, but the study did not measure actual time savings, student outcomes, feedback uptake, appeals or operational safety. Every AI output remained subject to instructor approval, and the system was not deployed in time to influence grades or feedback. “Acceptance-eligible” therefore described a retrospective selection rule, not observed instructor acceptance or automatic release of a grade.

Agreement also varied when measured at the level of weighted problem scores. The mean question-level intraclass correlation coefficient, ICC(2,1), was 0.700 for full-coverage Gemini, compared with 0.638 for the primary unanimity subset. These values describe different selected samples and do not establish a superiority of consensus. Reasoning–justification items had a mean unanimity-subset ICC of just 0.052, compared with 0.415 for Gemini over the full samples, because accepted model scores were often constant while instructor scores varied. A mapped proof-oriented course outcome had 83.1% accepted agreement and a 16.9% award-discrepancy share, whereas two Calculus outcomes reached accepted agreements of 95.1% and 93.8%. Course, task, rubric and instructor characteristics were confounded, so these were descriptive contrasts rather than causal effects of course learning outcomes.

The study supports a supervised decision aid in which cross-model disagreement and incomplete output trigger human review, while also exposing the limits of consensus. Rubric decomposition made each decision inspectable, but it could not compensate for missing criteria or rigidly under-credit unconventional reasoning. The evidence also raises fairness concerns because rigid criteria may under-credit valid approaches that differ from dominant forms, while shared model heuristics may over-credit responses resembling familiar disciplinary patterns; however, the study did not test subgroup fairness. Local validation remains necessary because the research covered three courses at one institution, used Thai rubric text with English instruction wrappers, did not independently annotate transcription accuracy and did not include a matched holistic-rubric comparison. Exact model access dates, decoding settings and some governance details were also unrecorded, limiting replication and independent verification of data-handling safeguards. The practical conclusion is neither autonomous grading nor wholesale rejection of AI assistance: unanimity can focus review, provided accepted decisions are audited, error direction is monitored and instructors retain final authority over every grade.

Subject of Research: Retrospective evaluation of multimodal AI grading and selective instructor review for undergraduate mathematics and computing assessments

Article Title: Direct multimodal grading of image-based mathematics and computing responses: rubric-constrained decisions and cross-model selective review

Article References: Rukkanchanunt, T., Chaidee, S., Isradisaikul, C., & Buchatip, K. (2026). Direct multimodal grading of image-based mathematics and computing responses: rubric-constrained decisions and cross-model selective review. Frontiers in Education, 11, Article 1948818. https://doi.org/10.3389/feduc.2026.1948818

Image Credits: AI Generated

DOI: 10.3389/feduc.2026.1948818

Keywords: multimodal AI, automated grading, handwritten responses, selective review, rubric decomposition, cross-model agreement, instructor oversight, higher education, assessment validity, Direct, multimodal, grading

Researchers analyzed electronic hospital records for patients with peptic ulcer disease identified by International Classification of Diseases, 10th Revision codes K25 through K29. The study used a prevalence-based, person-based approach because peptic ulcer disease is chronic and cure could not be assumed during the observation period. Costs included examinations, laboratory and imaging tests, functional investigations, medicines and infusions, hospital beds, blood, surgery, medical supplies, and selected non-medical expenses such as food and beverages.

All monetary amounts were initially recorded in Vietnamese dong. Annual costs were adjusted to 2024 using the consumer price index and converted to US dollars at the State Bank of Vietnam’s average exchange rate of VND 24,260 per USD. Patients transferred from gastroenterology to another department and those with incomplete records were excluded. Names, telephone numbers, addresses, and other identifiers had been anonymized before the research team received the data.

Patients’ mean age was 51.7 years, with a standard deviation of 17.4. The largest age groups were 30–54 years, representing 38.8% of the cohort, and 55–70 years, representing 35.2%. Mean hospital stay was 10.6 days, with a range of one to 63 days. Gastric ulcer was the most common diagnosis, while 79.3% of patients had at least one comorbidity. Half of the cohort resided in Ho Chi Minh City and 46.5% lived in other provinces.

Medical supplies were the largest component of the estimated cost, totaling USD 2,054,049, or 49.6% of the six-year total. Medicines and infusions accounted for USD 729,242, or 17.6%; hospital bed fees for USD 518,245, or 12.5%; surgery for USD 402,911, or 9.7%; laboratory tests for USD 257,241, or 6.2%; and diagnostic imaging for USD 129,338, or 3.1%. The share attributed to medical supplies was 1.6–29.4% during 2017–2020 before rising to 41.35% in 2021 and 65.3% in 2022.

Average cost per patient was USD 387.20 in 2017, USD 793.10 in 2018, USD 681.10 in 2019, USD 1,485.90 in 2020, USD 1,810.50 in 2021, and USD 3,784.30 in 2022. Annual numbers of included patients also varied, from 79 in 2017 to 601 in 2022, so the retrospective estimates do not establish that costs per admission alone caused the overall increase. The authors associated the late-period cost shift with more severe complications and comorbidities, which may have required more surgery, supplies, injections, and infusions.

Men accounted for USD 2,352,844, or 56.8%, of total costs, compared with USD 1,789,277, or 43.2%, for women; the Mann–Whitney U test showed a statistically significant difference in treatment costs between the groups. Civilian patients accounted for USD 3,906,872, or 94.3%, while military personnel accounted for USD 235,249, or 5.7%, with a significant difference between the groups. Patients with comorbidities generated USD 3,940,121, or 95.1%, of total costs, compared with USD 202,000, or 4.9%, for those without comorbidities.

Medicines specifically identified for peptic ulcer treatment totaled USD 88,640. Proton pump inhibitors represented 90.7% of that amount, or USD 80,350, with pantoprazole accounting for 64.5% of PPI costs and esomeprazole for 28.26%. Antibiotics represented 7.0%, mucosal protective agents 1.4%, and histamine-2 receptor antagonists 0.9%. In the sensitivity analysis, a hypothetical 10% reduction in medical-supply costs would lower total direct medical costs by 5.0%, compared with 1.8% for medicines and infusions, 1.3% for hospital beds, 0.97% for surgery, 0.6% for laboratory tests, and 0.3% for diagnostic imaging.

The findings have important boundaries. The study covered one final-tier military hospital that also provides insured and public services, rather than a nationally representative sample of Vietnamese patients with peptic ulcer disease. It estimated direct medical costs and part of the direct non-medical burden but did not include travel, accommodation for caregivers, lost income, or other indirect costs. The analysis also recorded only whether comorbidities were present, not their type or severity. Although the study was described as a cost-of-illness assessment rather than a clinical-effectiveness trial, its detailed service-level estimates provide a bounded measure of the direct resources used for inpatient peptic ulcer disease care at that hospital.

Subject of Research: Retrospective estimation of direct inpatient costs for peptic ulcer disease in a Vietnamese military hospital

Article Title: Analysis of direct medical costs for the treatment of peptic ulcer disease in inpatients at a military hospital: a retrospective study in Vietnam

Article References: Ong, T. D., Tran, V.-Q., Nguyen, P. N. M., Nguyen, H. M., Phan, N. M., Vo, B. V., Nguyen, T. D., & Vo, T. Q. (2026). Analysis of direct medical costs for the treatment of peptic ulcer disease in inpatients at a military hospital: a retrospective study in Vietnam. Pharmacia, 73, Article e201763. https://doi.org/10.3897/pharmacia.73.e201763

Image Credits: AI Generated

DOI: 10.3897/pharmacia.73.e201763

Keywords: peptic ulcer disease, Vietnam, cost-of-illness, retrospective study, hospital costs, medical supplies, military hospital, health economics, Analysis, direct, medical, costs

Researchers applied the CS-ARDL method to examine the evolving relationships among FDI, renewable energy consumption, energy intensity and CO₂ emissions. The model distinguished short-run from long-run associations rather than assigning each factor a single, constant relationship with emissions. The abstract does not provide country-specific estimates, uncertainty intervals, model diagnostics or the full set of model assumptions.

The reported empirical results associate short-run FDI inflows with increased emissions, which the authors interpret as reflecting investment allocated to pollution-intensive sectors. Over the longer term, the model associates FDI with lower emissions, an effect the authors attribute to the diffusion of cleaner and more developed production technology. These model results do not establish that increasing FDI would necessarily reduce emissions in every setting.

Renewable energy consumption was described as primarily improving environmental quality, but the study also associates its life-cycle emissions and related energy inefficiencies with higher emissions over time. Energy intensity had a positive association with CO₂ emissions in the short run and a negative association in the long run. The authors interpret the latter pattern as indicating the importance of energy-efficiency reforms. Overall, the findings concern the estimated relationships within the BRIC panel and 2000–2023 study period; the abstract does not establish that the same results apply identically to each country or beyond that period.

Subject of Research: Short- and long-run associations among FDI, energy use, energy intensity and CO₂ emissions in BRIC countries.

Article Title: Assessing the impact of foreign direct investment (FDI) and energy consumption on carbon dioxide emissions in BRIC nations

Article References: Imam, M. A., Abdelrehim, M., Al-alawnh, N. A. K., AL-Radaideh, I. S., Mujahed, M. M., Abbadi, A., & Hani, L. Y. B. (2026). Assessing the impact of foreign direct investment (FDI) and energy consumption on carbon dioxide emissions in BRIC nations. Discover Sustainability. https://doi.org/10.1007/s43621-026-04706-4

Image Credits: AI Generated

DOI: 10.1007/s43621-026-04706-4

Keywords: BRIC countries, foreign direct investment, CO₂ emissions, renewable energy, energy intensity, CS-ARDL, panel study, emerging economies, Assessing, impact, foreign, direct

Chironomidae are well suited to testing alternative molecular workflows because they are superabundant and species-rich members of freshwater communities, while their morphological identification is often difficult. Researchers collected emerging adults from artificial ponds at the Eußerthal Ecosystem Research Station near Landau, Germany, in 2019 and 2020. Specimens were sorted into four size classes because individual chironomids in the study differed in mass by more than a factor of 20. For tissue preparation, the insects were dried at 60 °C for 16 to 24 hours, finely ground with a TissueLyser II at 30 hertz for three one-minute cycles, suspended in PCR-grade water, vortexed and frozen at −20 °C. This procedure served as the starting material for direct PCR, whereas the conventional workflow began with extraction and purification of DNA from an equivalent portion of each homogenate.

Both workflows used a two-step PCR process targeting a 421-base-pair fragment of the mitochondrial cytochrome c oxidase I gene. The first PCR either received 1 microliter of purified DNA or 5 microliters of tissue-water suspension. Products were diluted 1:20 before the second PCR, in which fusion primers added Illumina adapters and sample-specific inline barcodes. Libraries were purified, size-selected with magnetic beads and sequenced as 250-base-pair paired-end reads on a MiSeq system. Demultiplexed reads were merged, quality-filtered and clustered into operational taxonomic units, or OTUs, at a 3% similarity threshold. For one artificial community whose members had very similar COI sequences, the researchers instead used amplicon sequence variants and assigned them to individual specimens through their Sanger-sequenced barcodes. Negative controls and duplicate technical PCRs were used to identify low-level contamination and inconsistent detections.

The artificial communities provided a controlled test of whether tissue mass and preparation method altered species detection. Mock A contained 16 chironomid specimens selected to differ by at least 1.5% in the targeted COI region, and five replicates were prepared under each principal workflow. One set of replicates used the same tissue-water volume for every specimen, simulating the variable masses expected without size-sorting; another used specimen-specific volumes adjusted to provide approximately 0.006 milligrams of tissue per individual. A second mock community, Mock B, contained 13 specimens with at least 13% sequence dissimilarity and provided an additional comparison. Across methods, 13 of the 16 Mock A specimens and all Mock B specimens were reliably detected in every replicate. Three Mock A taxa were detected in 95% to 97.5% of samples because one technical replicate in a small number of samples contained no reads for them.

Equalizing the amount of material supplied to the PCR reaction improved detection of the smallest specimens, but it did not make sequence-read abundance a reliable measure of individual biomass. Read counts varied more among taxa within a mock community than they did between the extracted-DNA and direct-PCR approaches, with Hedges’ g values greater than 0.8 in the comparisons. The observed heterogeneity also persisted after specimen mass was adjusted. In a separate experiment, researchers created four mock communities from 13 specimens using either equal amounts of purified total DNA or equal amounts of amplified target fragments. Equal purified-DNA inputs produced significantly different read abundances among OTUs, whereas equalizing the target fragments yielded no significant differences between specimens. Deviations from mean read abundance were significantly greater with equal total-DNA inputs, and varying the total-DNA input had essentially no linear relationship with read counts. By contrast, increasing the amount of target fragment in the second PCR explained 74% to 94% of read-abundance variation in the four mock communities.

These results indicate that much of the among-specimen variation arose during amplification rather than directly from specimen mass or the quantity of total DNA introduced into the first PCR. The authors identified primer bias as a probable contributor, although the study did not directly measure it, and noted that variation in mitochondrial copy number, heteroplasmy and nuclear pseudogenes could also influence read abundance. Their results therefore support interpreting chironomid metabarcoding primarily through presence–absence data rather than assuming that sequencing reads directly represent tissue mass or biomass proportions. A separate test of sensitivity also exposed a clear limit of the extraction-free workflow. Detection declined in every approach as the starting material was diluted, but the decline was substantially faster for direct PCR, whose amplification bands weakened more rapidly on agarose gels. OTUs that began with fewer than 50 reads disappeared in at least one dilution, whereas those with more than 700 reads were detected almost consistently across the tested range.

Natural communities were tested using 40 samples collected across five dates within 17 days from eight artificial ponds, four treated with the mosquito-control agent Bacillus thuringiensis israelensis and four left as controls. The samples came from an ongoing ecotoxicological study, and every community was processed by both direct PCR and the conventional extraction-based method. Sequencing identified 114 chironomid OTUs representing 36 genera. The methods differed for an average of 8.3% of the OTUs in pairwise sample comparisons, although six OTUs deviated between methods in more than four samples. Those frequently discrepant OTUs had relatively low mean abundance—no more than 10 reads—compared with an overall mean of 447 reads. A correspondence analysis showed substantial overlap between the workflows, and a permutational multivariate analysis of variance found significant effects of Bti treatment and sampling date, but no significant effect of DNA-preparation method on presence–absence community composition. In other words, both workflows supported the same conclusions about the ecological response to the treatment.

The practical implication is that DNA extraction can be omitted in at least some chironomid community metabarcoding without sacrificing the presence–absence information needed to characterize biodiversity or compare environmental treatments. Direct PCR is attractive for monitoring programs because extraction can be costly, labour-intensive and difficult to automate. The approach used here required drying, mechanical homogenization and suspension in water before amplification, rather than placing intact tissue directly into a PCR reaction. Modern polymerases and buffers also tolerate inhibitors more effectively than earlier formulations, which may further support the method. Eliminating extraction could reduce sample-processing time and costs and may fit workflows that aim to miniaturize molecular analysis for field or on-site use. However, the study did not directly measure a formal cost comparison, so the expected economic benefit remains a proposed advantage rather than a quantified result.

Important limits constrain how broadly the findings can be applied. The study focused on chironomids and used a specific homogenization, dilution and PCR protocol, so performance may differ among arthropod groups with tougher tissues, pigmentation, secretions or other PCR inhibitors. Earlier direct-PCR work had reported lower success for some beetles, copepods, ants and dragonflies. Although the chironomid protocol produced successful COI amplification for specimens spanning several arthropod orders in supporting tests, the authors emphasized that mixed arthropod samples would require representative mock communities to reveal taxon-specific bias. Direct PCR was also less robust than purified DNA when very small amounts of material were pipetted, and its read counts were more variable. The evidence therefore supports direct PCR as a valid option for chironomid presence–absence monitoring, particularly when speed and simpler sample preparation matter, rather than as a universal replacement for extraction or as a direct measure of organism abundance.

Overall, the experiments show that a carefully prepared tissue suspension can substitute for purified DNA in chironomid community metabarcoding. Artificial communities demonstrated similar detection rates, while natural pond samples showed high agreement in species composition and identical treatment-related conclusions under the two workflows. The approach cannot yet match extraction in sensitivity to diluted material, nor can its sequence reads be treated as exact proxies for biomass, but it preserves the principal compositional signal needed for ecological monitoring. For researchers working with chironomid communities, the study offers a practical alternative that removes one of the most demanding stages of metabarcoding and could make large-scale biodiversity surveys faster and less expensive, while still requiring validation when transferred to other insect assemblages or lower-input samples.

Subject of Research: Direct PCR for high-throughput metabarcoding of chironomid insect communities

Article Title: Direct PCR meets high-throughput sequencing – metabarcoding of chironomid communities without DNA extraction

Article References: Röder, N., & Schwenk, K. (2023). Direct PCR meets high-throughput sequencing – metabarcoding of chironomid communities without DNA extraction. Metabarcoding and Metagenomics, 7, Article e102455. https://doi.org/10.3897/mbmg.7.102455

Image Credits: AI Generated

DOI: 10.3897/mbmg.7.102455

Keywords: direct PCR, DNA metabarcoding, chironomids, biodiversity monitoring, high-throughput sequencing, environmental DNA, COI barcoding, ecotoxicology, arthropod communities, Direct, meets, high-throughput

The study focused on direct mortality rather than inferred changes in population size. Researchers walked across burned areas in a zigzag pattern, generally within the first two weeks after a fire and in some cases as late as three weeks, recording every live or dead reptile they encountered. The 2021 survey covered 120.60 hectares during 18 field days and about 300 person-hours, while the 2022 effort surveyed 28.95 hectares over four days and 66 person-hours. Satellite imagery helped identify additional burned areas that could not be visited. Investigators used global positioning system measurements and a geographic information system to calculate areas and densities, while photographs documented animals and their locations. Carcasses were left in place because they can serve as food for predators and scavengers.

Fire affected 196.91 hectares of Sierra Morelos in 2021 and 63.33 hectares in 2022. Authorities reported 35.9 hectares of prescribed burning in 2021, compared with an annual average of 2.65 hectares between 2013 and 2020. The researchers surveyed 23.72 hectares of prescribed burns and 96.88 hectares of unplanned burns in 2021; in 2022, all 28.95 hectares surveyed were prescribed burns. The managed fires were intended to protect plantations of non-native trees, particularly Mexican pine and eucalyptus, which are highly flammable. Unplanned fires included illegal or accidental ignitions associated with agricultural and grazing activities, trash burning near informal settlements, abandoned campfires and discarded cigarettes.

Among the reptiles recorded in the 2021 burned areas, 58 were dead and 111 alive, meaning that 34% of the observed population had been killed. In 2022, 11 were dead and 22 alive, a mortality fraction of 33%. Overall carcass density across all sampled areas was 0.48 individuals per hectare in 2021 and 0.38 per hectare in 2022. The mean among individual sampling sites was considerably more variable, reaching 1.60 ± 2.99 individuals per hectare in 2021 and 0.31 ± 0.27 in 2022. One small prescribed firebreak produced the highest site-level density in 2021, with 12.26 carcasses per hectare, including three garter snakes. By contrast, a large 73.73-hectare site affected by an out-of-control stubble fire contained 20 carcasses, illustrating how total deaths and density can tell different stories.

Prescribed and unplanned burns produced no statistically detectable difference in carcass density in 2021, with a Mann–Whitney U result of W = 37.5 and p = 0.4383. In that year, 53% of reptiles found in prescribed-burn sites were dead, compared with 30% in unplanned-burn sites, but the number of sites and the high variation among them prevented the difference from reaching statistical significance. The researchers also found no relationship between carcass density and a simple measure of fire shape based on area divided by perimeter, which yielded R² = 0.0528 and p = 0.168. That measure did not account for rocks, agave plants, logs, burrows, wind, speed or severity, all of which could influence where animals survived.

The Mexican plateau horned lizard, Phrynosoma orbiculare, was the most frequently killed species and a particularly troubling casualty because it is threatened in Mexico. Twenty horned lizards were found dead in 2021 and four in 2022. The species shelters beneath bunchgrass or leaf litter when inactive and moves slowly, leaving it exposed when flames pass through its cover. Its carcass densities were 0.17 per hectare across the sampled area in 2021 and 0.14 per hectare in 2022. The torquate lizard, Sceloporus torquatus, was far more abundant but had a much lower death rate: nine of 70 observed individuals died in 2021 and three of eight in 2022. Its ability to climb rocks, shrubs, agave plants and fallen logs likely gave it access to more effective refuges. Researchers also noted that three horned lizards were intercepted and moved away from an active fire.

Ground-dwelling snakes were another major casualty. Nineteen garter snakes of the genus Thamnophis were found dead in 2021 and two in 2022. Three of the carcasses showed no visible thermal damage despite lying on completely burned ground. Garter snakes can retreat into burrows and underground cavities, including hollows more than a meter deep, but such protection may not prevent death from smoke inhalation, toxic gases or oxygen depletion. Their presence as intact, apparently unburned bodies on burned surfaces suggests that some may have sheltered below ground during the flames and emerged only after the surrounding vegetation had been consumed. The transvolcanic alligator lizard, Barisia imbricata, was relatively uncommon but yielded 10 carcasses, reinforcing concern that other ground-dwelling species may also have been disproportionately affected.

The observed totals are likely conservative. Carcasses can be hidden beneath ash, fragmented beyond recognition or entirely calcined; one horned lizard was so completely burned that it fell apart when photographed. Predators and scavengers may remove bodies before surveys begin, and the investigators noted that one previous study documented a 20% decline in carcass counts during the second week after fire. Some injured survivors may also have died after the survey through burns, dehydration or indirect effects. Reptiles that survived may have moved away before investigators arrived, and animals dying underground may never have been detectable. Conversely, the researchers excluded likely roadkill or other non-fire deaths from the analysis, and live animals found during surveys were released near burned-area edges to help them escape short-term threats.

Most carcasses in 2021 lay on burned grass, which accounted for 84% of the total, followed by leaf litter, rocky surfaces and bare soil. All carcasses found in 2022 were on burned grass. Even burns conducted in January and February, when reptiles may be less active, occurred during the cold and dry season, but inactivity did not necessarily mean deep shelter. Sierra Morelos has pronounced daily temperature swings, with winter nights sometimes below freezing and daytime temperatures above 20°C. Horned lizards may remain beneath bunchgrass or leaf litter even during cooler periods, placing them directly in the path of burning vegetation. The findings therefore do not support the assumption that winter scheduling alone is sufficient protection in this high-elevation grassland environment.

For conservation, the authors call for changes to fire management in Sierra Morelos and similar regional grasslands. They recommend ending prescribed burns as part of the reserve’s management program while also reducing the larger annual area affected by unplanned fires, which collectively pose a cumulative threat. Suggested measures include maintaining a distributed network of bike paths as firebreaks, rotating small-scale livestock use to limit fuel accumulation without intensifying grazing, replacing flammable pine and eucalyptus plantations with native vegetation, and coordinating dry-season vigilance among nearby communities. Restoring landscape features such as agave plants could provide refuges, while rapid post-fire searches could identify survivors for cooling, relocation or other assistance. More systematic monitoring of live and dead reptiles before and after fire would permit more precise estimates of mortality and help determine which management practices protect vulnerable populations without reducing the frequency of unplanned ignition.

Subject of Research: Direct fire-induced mortality among reptiles in a Mexican natural protected area

Article Title: Direct fire-induced reptile mortality in the Sierra Morelos natural protected area (Mexico)

Article References: González-Fernández, A., Couturier, S., Dotor-Diego, R., Martínez-Díaz-González, R., & Sunny, A. (2024). Direct fire-induced reptile mortality in the Sierra Morelos natural protected area (Mexico). Herpetozoa, 37, 213-226. https://doi.org/10.3897/herpetozoa.37.e116376

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.37.e116376

Keywords: reptile mortality, wildfire, prescribed burning, Sierra Morelos, Mexico, hornied lizards, garter snakes, fire ecology, protected areas, anthropogenic fire, Direct, fire-induced

The strategy, which the authors call cascading utilization, treats the lithium-ion sieve as a two-stage asset rather than a single-use consumable. In the first stage, the spinel framework performs its designed job of selectively extracting lithium from aqueous resources. In the second stage, the same powder, now depleted and structurally altered by hundreds of lithium extraction cycles, is converted into a functional electrode for a completely different electrochemical device. This cross-domain repurposing addresses a genuine sustainability problem: lithium-ion sieve powders are expensive to synthesize, requiring high-temperature solid-state reactions and careful acid treatment, and throwing them away after their sieving performance declines wastes both the embedded manganese and the energy invested in their manufacture.

The central challenge in converting a cycled sieve into a battery cathode lies in the chemistry of the spinel itself. Fresh H1.6Mn1.6O4 is essentially a lithium-depleted manganese oxide with a dense spinel lattice, and its suitability for hosting zinc ions, which are divalent and much larger than lithium ions, is far from obvious. Zinc-ion batteries store charge by intercalating Zn2+ into host structures at the cathode, and polyvalent cations like zinc diffuse sluggishly through tight crystal frameworks. The researchers recognized, however, that the repeated lithium extraction process the sieve had already endured might have done some of the activation work for them. Each cycle of Li+ removal and reinsertion subtly reshapes the spinel, and the team hypothesized that these structural changes could create favorable diffusion pathways for zinc.

To prepare the cycled powder for its new role, the team applied a photo-excitation-assisted oxidative delithiation process using sodium persulfate as the oxidant. This step removes any residual lithium left in the framework after the sieving cycles while preserving the spinel structure. Conventional acid-based delithiation methods, such as treatment with hydrochloric acid, are known to cause manganese dissolution, which erodes the spinel lattice and degrades performance. The persulfate approach, assisted by photo-excitation, is gentler: it oxidatively extracts lithium without the harsh acidic conditions that dissolve manganese from the framework. The result is a material that retains high structural integrity while carrying the surface activation and diffusion pathways introduced by its prior life as a sieve.

When the regenerated material was assembled into cathodes and tested in aqueous zinc-ion batteries, the performance confirmed the team’s hypothesis. The directly regenerated lithium-ion sieve delivered a reversible capacity of 101.5 mAh per gram at a current density of 0.03 A per gram, a respectable figure for a spinel manganese oxide cathode operating through zinc intercalation. More striking was the cycling stability: the material exhibited a Coulombic efficiency of approximately 99 percent over 200 cycles, indicating that nearly every unit of charge inserted into the cathode during each cycle was recoverable on discharge. Coulombic efficiency close to 99 percent sustained over hundreds of cycles is a hallmark of an electrode whose intercalation chemistry is well matched to the electrolyte and whose structural framework survives repeated zinc insertion and extraction without collapse.

The mechanism behind this performance is rooted in the dual benefit the cycled sieve carries into the battery. First, the repeated Li+ extraction cycles that the material endured during lithium recovery introduced favorable diffusion pathways within the spinel framework, effectively pre-etching channels through which Zn2+ can travel during charge and discharge. Second, the surface activation that accumulates over many sieving cycles lowers the energetic barrier for zinc intercalation at the particle surface, facilitating Zn2+ storage. In effect, the very process that wears out the sieve as a lithium extractor is the process that primes it as a zinc host. This is what makes the cascading strategy so elegant: the degradation in one application is the activation in another.

The connection between lithium-ion sieves and zinc-ion battery cathodes runs deeper than mere convenience, and the researchers situate their work within an established lineage of spinel manganese oxide research. When LiMn2O4 spinel is delithiated, the product is a metastable form of manganese dioxide known as λ-MnO2, first prepared as a new crystal form of manganese dioxide in 1981. λ-MnO2 and related spinel manganese oxides have long been investigated as intercalation hosts for polyvalent cations including Mg2+ and Zn2+ in aqueous batteries. Spinel zinc manganates, formed when zinc intercalates into these frameworks, are recognized cathode materials for zinc-ion batteries. The cycled H1.6Mn1.6O4 sieve, having already been stripped of most of its lithium, occupies precisely this chemical territory, which explains why it can function as a zinc host without extensive reprocessing.

What distinguishes this study from prior recycling efforts is the directness of the conversion. Previous work has regenerated spent lithium manganate battery materials into doped manganese dioxide cathodes for aqueous zinc batteries, and other teams have selectively recycled spent lithium-ion battery components into zinc-ion battery cathodes. But those approaches typically start from battery materials and involve substantial reprocessing, such as doping with aluminum or other elements to stabilize the framework. The Northeastern University team instead starts from an industrial adsorbent, a material whose primary function was never electrochemical, and uses it directly as a cathode after only a mild delithiation treatment. No doping, no reconstruction, no synthesis of a new compound: the cycled sieve powder is simply delithiated, washed, and made into an electrode.

The implications for resource efficiency are considerable. Lithium-ion sieves are deployed in some of the most demanding environments in the chemical industry, from salt-lake brines to shale gas wastewater, and the field has invested heavily in improving their selectivity, capacity, and stability. Researchers have tailored lattice constants and intercalation energies to boost performance, doped sieves with titanium, tungsten, lanthanum, and other high-valence elements to suppress manganese dissolution, and engineered porous and granular structures to improve kinetics. All of this engineering makes the sieves more valuable, and all of it is lost when the cycled powder is discarded. The cascading utilization strategy recovers that value by routing the spent adsorbent into energy storage, where its structural framework, its embedded manganese, and even its cycling-induced defects all contribute to function.

For zinc-ion batteries themselves, the study offers a new avenue toward low-cost and sustainable cathode materials. Aqueous zinc-ion batteries are attractive because they use water-based electrolytes, inexpensive zinc metal anodes, and ambient-air assembly, making them inherently safer than lithium-ion systems and well suited to stationary storage. Their main bottleneck has been the cathode: manganese dioxide and vanadium oxide hosts suffer from dissolution, structural instability, and sluggish zinc diffusion. A cathode derived from a recycled industrial adsorbent, with pre-existing diffusion pathways and a spinel framework proven stable over hundreds of lithium extraction cycles, addresses several of these issues at once. The team confirmed the feasibility of cross-domain application of cycled lithium-ion sieve powder, and in doing so opened a path where the waste stream of one clean technology, lithium recovery from brine, feeds directly into the supply chain of another, grid-scale zinc battery storage. As demand for both lithium and stationary energy storage accelerates worldwide, strategies that link the two, turning one technology’s spent materials into another’s functional components, may prove to be among the most resource-efficient ideas in the battery field.

Subject of Research: Materials Science

Article Title: Direct cascading utilization of cycled H1.6Mn1.6O4 lithium-ion sieves as cathodes for zinc-ion batteries

Article References: Liu, X., Li, Y., Yang, H., & Li, F. (2026). Direct cascading utilization of cycled H1.6Mn1.6O4 lithium-ion sieves as cathodes for zinc-ion batteries. Ionics. https://doi.org/10.1007/s11581-026-07575-z

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07575-z

Keywords: lithium-ion sieve, zinc-ion batteries, H1.6Mn1.6O4, cathode recycling, spinel manganese oxide, sustainable energy storage, lithium recovery, cascading utilization, Direct, cascading, utilization, cycled

The study was led by Youquan Gu of The First Affiliated Hospital of Lanzhou University in China, together with colleagues from Lanzhou University and Gansu Provincial Hospital. The team enrolled 234 patients treated for acute ischemic stroke, the most common form of stroke, caused by a blockage of blood flow to part of the brain. All laboratory values were drawn at admission, before any treatment began. The researchers then tracked two outcomes: the initial severity of the stroke, measured with the National Institutes of Health Stroke Scale, and the functional status of patients at discharge, measured with the modified Rankin Scale.

Bilirubin is a yellow pigment produced when the body breaks down heme, the iron-containing molecule at the core of hemoglobin. It has long been viewed mainly as a liver-related value, but in recent years scientists have recognized that it also acts as a powerful antioxidant, neutralizing reactive molecules that damage tissue. Direct bilirubin is the form that has been processed by the liver and released into the blood. Because stroke triggers an intense inflammatory response that generates reactive oxygen species, researchers have suspected that bilirubin might be consumed in the process, making blood levels a potential window into the intensity of the inflammatory storm.

The results were striking. Patients with higher direct bilirubin levels at admission had significantly more severe strokes, and direct bilirubin was an independent predictor of stroke severity even after accounting for other clinical factors. The derived ratio, DBLR, performed even better. Patients with higher DBLR values had both more severe strokes and worse functional outcomes at discharge. In statistical models, DBLR was an independent predictor of both outcomes, suggesting that the ratio captures something that direct bilirubin alone does not.

The mechanism behind the ratio may lie in the two values that make it up. Lymphocytes are white blood cells that help coordinate the immune response, and their numbers typically drop during acute inflammatory events, a phenomenon clinicians call lymphopenia. Because severe strokes trigger a more intense inflammatory response, they cause a greater drop in lymphocyte counts. Dividing direct bilirubin by the lymphocyte count therefore produces a value that rises when the inflammatory storm is intense, combining a marker of antioxidant consumption with a marker of immune suppression in a single number.

The clinical implications are significant. Because both direct bilirubin and lymphocyte counts are measured routinely in every hospital laboratory, DBLR could be calculated within minutes of a patient’s arrival, without any additional cost or delay. The researchers suggest that the ratio could eventually help clinicians identify patients at high risk of severe disability, guiding decisions about treatment intensity and rehabilitation planning. The value could also serve as a rapid and objective way to track the intensity of the inflammatory response during the hospital stay.

The study has limitations. It was conducted at a single center in China, and the findings will need to be replicated in larger and more diverse populations. The researchers also note that the ratio was associated with outcomes during the hospital stay, but the study did not track patients after discharge, so the long-term implications remain unknown. In addition, because bilirubin levels can be affected by liver disease and other conditions, clinicians would need to account for factors that could distort the value.

Even so, the findings add to a growing body of evidence that routine laboratory values can serve as unexpected windows into stroke severity. Previous studies have linked bilirubin levels to the severity of atherosclerosis, the buildup of plaque in arteries that underlies many strokes, and to the intensity of the inflammatory response that follows. The new study extends this work by showing that a derived ratio combining two routine values may capture the clinical picture even better than either value alone.

The researchers suggest that future studies should track patients after discharge, replicate the findings in larger populations, and explore whether the ratio could guide treatment decisions in real time. If the results hold up, a value calculated from a routine blood test could eventually become part of the standard clinical picture for acute stroke, helping clinicians answer one of the most urgent questions in medicine: how bad is this going to be?

Subject of Research: Admission direct bilirubin and direct bilirubin-to-lymphocyte ratio as exploratory markers of early severity and in-hospital functional status in acute ischemic stroke

Article Title: Admission direct bilirubin and direct bilirubin-to-lymphocyte ratio as exploratory markers of early severity and in-hospital functional status in acute ischemic stroke

Article References: Li, Y., Zhang, R., Luo, Y., & Gu, Y. (2026). Admission direct bilirubin and direct bilirubin-to-lymphocyte ratio as exploratory markers of early severity and in-hospital functional status in acute ischemic stroke. Frontiers in Stroke, 5, Article 1800285. https://doi.org/10.3389/fstro.2026.1800285

Image Credits: AI Generated

DOI: 10.3389/fstro.2026.1800285

Keywords: Admission, direct, bilirubin, bilirubin-to-lymphocyte, ratio, exploratory, markers, early, severity, in-hospital, functional, status

The review, led by Mohammad Khursheed Alam of Jouf University in Saudi Arabia and Suliman Alsaeed of King Saud bin Abdulaziz University for Health Sciences, was conducted according to the PRISMA 2020 reporting standard and registered in PROSPERO. The team searched PubMed/MEDLINE, Scopus, Web of Science Core Collection, EMBASE, and the Cochrane Library from January 2010 through October 2025, supplementing the search with Google Scholar screening and reference-list checks. Crucially, the search strategy used two reproducible concept blocks—orthodontics and environmental sustainability—without a human-subject filter, so that laboratory studies and life-cycle assessments remained eligible alongside surveys of practitioners.

That strictness was intentional. The authors note that much of the existing orthodontic sustainability literature mixes direct environmental measurements with indirect clinical, microbiological, or material outcomes, allowing clinical novelty to be mislabeled as evidence of ecological benefit. By restricting eligibility to primary studies with a direct environmental link, the review produced a highly selected evidence base: two laboratory or material studies, one comparative life-cycle assessment, and two cross-sectional surveys. The small number itself is an important finding, revealing how sparse direct evidence remains despite extensive discussion of sustainable orthodontics.

The most eye-catching result concerns the end-of-life fate of clear aligners, the transparent thermoplastic appliances that have transformed orthodontic treatment. In a laboratory study from India, researchers used gas chromatography-mass spectrometry to analyze the smoke generated by incinerating used PET-G and polyurethane aligners. The analysis detected measurable hazardous volatile compounds, providing direct evidence that routine incineration of aligner waste cannot be assumed to be environmentally benign. However, the experiment assessed only selected materials and disposal conditions and did not compare a complete set of recycling or recovery pathways, so its conclusions are necessarily bounded.

The comparative life-cycle assessment, conducted by researchers in Ireland and the UK, examined Hawley and Essix retainers—the wire-and-acrylic appliances versus the vacuum-formed plastic ones—across 16 impact categories. On production alone, Hawley retainers carried a higher burden in 12 of the 16 categories. But the picture changed once product lifespan and replacement frequency were modeled: over the specified period, under the stated assumptions, Hawley retention emerged as having the lower environmental burden. The finding demonstrates why functional unit, durability, replacement, and system boundaries are central to any orthodontic sustainability decision, and why simple labels such as recyclable, digital, or plastic-free can mislead without specifying end-of-life scenarios.

Life-cycle assessment evidence requires particular caution because results are conditional on modeling choices. Geographic electricity generation, transportation distance and mode, manufacturing location, inventory-database selection, waste-treatment pathways, and expected replacement frequency can all materially alter comparative estimates. The review’s authors emphasize that even apparently similar appliance comparisons performed in different settings may not be directly comparable, and that an environmentally preferable result in one modeled scenario should not be treated as a universal property of the appliance.

The third domain concerned material innovation. An Italian in vitro study evaluated a shape-memory, 4D-printed aligner material through morphological, optical, thermomechanical, and cyclic testing. Heat-triggered shape recovery was reversible without loss of usability, supporting the concept that a single appliance might deliver more than one programmed stage of treatment and thereby reduce material consumption. Yet the study did not perform a cradle-to-grave life-cycle assessment. The review treats this finding strictly as evidence of material-function potential: fewer appliances do not automatically guarantee a lower total footprint, because printing energy, resin synthesis, activation steps, failed prints, transport, device life, and disposal must all be quantified before any net environmental benefit can be claimed.

The two surveys provide complementary implementation evidence. In India, a cross-sectional survey of 760 orthodontists and general dentists found that orthodontists reported safer clear-aligner disposal more often than general dentists, but both groups showed gaps in knowledge of biodegradation and disposal regulation. Regular garbage disposal and transfer of disposal responsibility to patients remained common. In the UK, a survey of 146 British Orthodontic Society members—yielding a 10 percent response rate—found that environmental sustainability was widely regarded as important, with respondents prioritizing reduction of plastics, recycling of consumables, and rethinking waste management. Cost, regulation, organizational policy, and feasibility were prominent barriers. The review cautions that these are self-reported attitudes and practices, vulnerable to self-selection and social-desirability bias, and that the identified barriers should be read as perceived constraints rather than demonstrated causes of environmental outcomes.

Methodological appraisal, matched to study design rather than applying a single tool, found that all five studies had some concerns overall, concentrated in sample or functional-unit selection, modeling assumptions, confounding, response bias, and limited sensitivity analysis. None was considered unusable for a cautious narrative synthesis, but the review did not apply formal certainty grading because the evidence spans fundamentally different designs and non-comparable outcomes—chemical emissions, multiple life-cycle impact categories, thermomechanical material behavior, disposal knowledge, and implementation attitudes. Meta-analysis was inappropriate for the same reason: a pooled effect estimate would have no coherent interpretation.

Geographic generalizability is also limited. The included evidence originated from only a few countries and healthcare systems, and the review does not adequately characterize lower-resource settings or the diversity of waste-management and regulatory contexts worldwide. Local energy generation, transport logistics, procurement structures, recycling access, infection-control requirements, and waste regulation may materially alter both life-cycle estimates and the feasibility of implementation. The search was restricted to English-language reports, which may have missed locally published evidence from settings where energy mixes, regulation, and recycling infrastructure differ substantially.

For clinicians, the review supports cautious, intervention-specific actions: clear-aligner incineration should not be assumed to be environmentally benign; retainer longevity and replacement should be considered alongside production burden; and material-saving technologies should remain described as promising until full life-cycle evidence is available. For institutions and policymakers, the survey findings support clearer disposal guidance and greater attention to procurement, recycling pathways, and manufacturer instructions. Take-back schemes and standardized procurement criteria remain proposals for future evaluation rather than established evidence-based interventions.

Looking ahead, the authors call for prospective comparative life-cycle assessments with explicit functional units, system boundaries, local energy and transport data, uncertainty analysis, and clinically realistic replacement rates. Clear aligners, fixed appliances, retainers, packaging, remote monitoring, digital models, and reusable alternatives should be compared across manufacturing, clinical use, travel, and end-of-life stages. Material innovations should report both clinical performance and environmental inventory data, and implementation studies should test whether manufacturer instructions, take-back schemes, procurement standards, staff training, and policy changes measurably reduce waste or emissions rather than only improving attitudes. The direct evidence for sustainable orthodontics is limited but clinically relevant, and firm recommendations will require standardized environmental outcomes and orthodontic-specific life-cycle assessment before any technology, material, or appliance category can be credibly labeled sustainable.

Subject of Research: Sustainable orthodontics: direct environmental, material, and implementation evidence from a systematic review

Article Title: Sustainable orthodontics: direct environmental, material, and implementation evidence from a systematic review

Article References: Alam, M. K., Alsaeed, S., Hajeer, M. Y., Abutayyem, H., Alayyash, A., & Alhajeri, K. (2026). Sustainable orthodontics: direct environmental, material, and implementation evidence from a systematic review. Frontiers in Oral Health, 7, Article 1772579. https://doi.org/10.3389/froh.2026.1772579

Image Credits: AI Generated

DOI: 10.3389/froh.2026.1772579

Keywords: orthodontics, environmental sustainability, life-cycle assessment, clear aligners, systematic review, waste disposal, dental materials, healthcare carbon footprint, Sustainable, direct, environmental, material