The research team, led by Catarina Ermida of the Laboratory of Forensic Anthropology, together with Eugénia Cunha, Francisco Gil and Maria Teresa Ferreira, drew on a uniquely well-documented resource: identified skeletal collections in Portugal, including the 21st Century Identified Skeletal Collection at Coimbra and clavicles recovered from autopsies at the Portuguese National Institute of Legal Medicine and Forensic Sciences. Because the identities and death dates of these individuals are known with documented precision, the researchers could work with genuinely known postmortem intervals, something that is remarkably rare in this field. In total, 38 unburned human clavicles were analyzed, spanning PMIs from 4 to approximately 500 years. To probe the effects of heat, the team added a subsample of 12 clavicles that had been burned and carried a PMI of only four years, providing a natural experiment in how thermal alteration reshapes bone mineral independently of time.

The technique at the heart of the study, X-ray diffraction, is one of the workhorses of materials science. When a beam of X-rays strikes a crystalline substance, the atoms scatter the radiation in patterns dictated by the regular arrangement of the crystal lattice. Bone mineral, a poorly crystalline form of calcium phosphate closely related to the mineral hydroxyapatite, produces characteristic diffraction peaks. Freshly formed bone contains many small, imperfect, strain-laden crystals, and their disorder broadens and smears the diffraction peaks. As bone ages, and especially as it is altered by the burial environment, crystals tend to recrystallize and coarsen: small crystals dissolve and redeposit onto larger ones, lattice defects are repaired, and the peaks become taller, narrower and sharper. Two parameters capture this maturation. The crystallinity index, or CI, is calculated from the relative sharpness of the diffraction pattern, essentially a ratio comparing the height of key peaks with the depth of the trough between them. Crystallite size, meanwhile, is estimated from the broadening of the diffraction peaks themselves, using the physical principle that smaller crystals produce wider peaks. If bone mineral truly aged like a clockwork, both numbers should climb steadily with time since death.

That is roughly what the study found for the crystallinity index, but not for crystallite size. Across the 38 unburned clavicles, crystallite size showed no consistent relationship with PMI at all; values fluctuated widely from sample to sample, swamped by variability that had nothing to do with elapsed time. The crystallinity index told a different story. It displayed a moderate positive correlation with postmortem interval, with a Spearman rank correlation coefficient of 0.587, a statistically significant result with a p value below 0.001 and a 95 percent confidence interval stretching from 0.194 to 0.810. In plain terms, older bones did tend, on average, to show sharper, more crystalline diffraction patterns, consistent with the long-standing picture of slow diagenetic recrystallization. For archaeologists sorting ancient from modern material, that trend is real and useful. But the confidence interval also reveals how noisy the relationship is, and the devil, as so often in forensic science, was hiding in the scatter.

That scatter is precisely what limits the forensic dream. The authors observed substantial overlap in crystallinity values within the forensic timescale, meaning that a bone dead for five years might produce a CI indistinguishable from one dead for twenty or thirty years. Samples with identical known PMIs returned markedly different crystallinity values, a pattern the researchers attribute to taphonomic factors, the full suite of environmental insults that a body experiences after death: soil chemistry, moisture, pH, temperature swings, microbial attack, roots, and drainage. Two skeletons buried for the same number of years in different microenvironments can follow very different diagenetic trajectories, so the mineral fabric they present to an X-ray beam reflects burial history as much as burial duration. In forensic casework, where the difference between a recent death and a decades-old one can determine whether a crime is prosecuted, that ambiguity is decisive. A method that produces overlapping values across the critical range cannot pin a date, only gesture at one.

The burned-bone subsample added a further warning. Heat is known to drive dramatic recrystallization in bone mineral: as temperatures rise during burning, the small bioapatite crystals grow, merge and reorganize, sharpening diffraction patterns dramatically. The 12 burned clavicles in the study, all with a PMI of just four years, showed thermal alteration of crystallinity that could, in effect, mimic the signature of much older remains. A forensic investigator who analyzed a burned recent bone and interpreted its high crystallinity as a sign of antiquity would be badly misled. Conversely, cremated archaeological material could masquerade as fresh if the thermal signature were misread. The study’s authors stress that thermal history must be recognized and accounted for before any crystallinity measurement is interpreted as a proxy for time, and their data demonstrate concretely how fire can scramble the clock that X-ray diffraction is meant to read.

None of this means X-ray diffraction is useless in forensic contexts. The technique is fast, relatively inexpensive, minimally destructive, and its parameters do track genuine postmortem change in bone mineral. The crystallinity index’s moderate correlation with PMI confirms that mineral maturation is a real, measurable phenomenon, and the study’s use of documented skeletal collections shows how such measurements can be calibrated against known truth rather than assumed ages. What the findings deflate is the more ambitious claim: that CI or crystallite size alone can deliver a precise postmortem interval. The results align with a growing body of literature that has tested physicochemical dating proxies, from earlier X-ray diffraction studies to spectroscopic approaches, and found the same recurring pattern, a broad correlation with time that dissolves into scatter exactly where forensic questions need resolution. The authors conclude that, although XRD-derived crystallinity parameters provide useful insights into postmortem changes in bone mineral structure, their application for PMI estimation remains limited.

There is a broader lesson here about how forensic science progresses, and it is one worth savoring. The temptation in a young and under-resourced field is to chase a single magic number, a lone chemical or crystallographic readout that solves the dating problem once and for all. This study, grounded in 50 human clavicles with known histories, shows why that chase so often disappoints: death does not happen in a laboratory, it happens in soil, in water, in fire, and in a thousand uncontrolled environments that each rewrite the bone record in their own way. The measured effect of time is real but entangled with the effects of everything else. Progress will likely come not from a solitary indicator but from combinations of methods, larger and better-documented reference collections, and models that explicitly incorporate taphonomic variables rather than wishing them away.

For now, the crystals in our bones keep their secrets stubbornly. They do grow and ripen after death, and a diffractometer can watch it happen. But between a fresh forensic case and a centuries-old skeleton, the crystalline clock runs at different speeds in different graves, and fire can knock its hands sideways entirely. The Coimbra team’s careful negative result is, in its way, as valuable as a breakthrough: it tells every future investigator exactly where the limits lie, and redirects the hunt for the forensic clock of death toward approaches humble enough to respect the chaos of the burial world. Until then, the question of how long ago someone died will continue to demand the oldest tools of all, careful context, cautious inference, and the accumulated judgment of forensic anthropologists who know that every bone tells more than one story.

Subject of Research: X-ray diffraction analysis of bone mineral crystallinity as a potential marker of the postmortem interval in human skeletal remains

Article Title: X-ray diffraction analysis of bone crystallinity and its association with postmortem interval in human skeletal remains

Article References: Ermida, C., Cunha, E., Gil, F., & Ferreira, M. T. (2026). X-ray diffraction analysis of bone crystallinity and its association with postmortem interval in human skeletal remains. International Journal of Legal Medicine. https://doi.org/10.1007/s00414-026-04020-8

Image Credits: AI Generated

DOI: 10.1007/s00414-026-04020-8

Keywords: X-ray diffraction, bone crystallinity, postmortem interval, forensic anthropology, human skeletal remains, crystallinity index, crystallite size, taphonomy, bone diagenesis, burned bone, time since death, International Journal of Legal Medicine

The significance of the work lies in the mounting pressure on the global dissolving pulp supply chain. The market for dissolving-grade pulp was valued at approximately 5,540 million US dollars in 2023 and is projected to grow at a compound annual rate of 3.3 percent through 2032, driven largely by rising demand for man-made cellulosic fibres in emerging economies such as China and India. Traditionally, the industry has relied on wood pulp and cotton linters, but rising pulpwood prices and growing deforestation concerns have intensified the search for fast-growing, renewable alternatives. Bamboo, a woody grass in the subfamily Bambusoideae encompassing roughly 1,250 species in 75 genera, offers abundant fibre, rapid regeneration, high carbon sequestration potential and the ability to thrive on degraded land — yet systematic, side-by-side comparisons of species and harvest ages have been largely missing from the literature.

Dissolving pulp is not ordinary paper pulp. It is a chemically refined, low-yield product with an overall fibre-line yield of only 30 to 35 percent, engineered to contain 90 to 99 percent pure cellulose, less than 4 percent hemicelluloses, and only trace amounts of lignin, resins and inorganic impurities. Grades are classified by cellulose content: low grades at about 90 percent serve textiles and cellophane, medium grades at roughly 94 to 95 percent, and high grades above 96 percent are reserved for cellulose acetate and specialty derivatives. Because the pulp is ultimately dissolved and regenerated or chemically modified, its reactivity — the accessibility of hydroxyl groups on the cellulose chain — is a critical quality parameter, demanding a narrow molecular weight distribution, an open porous structure and minimal microfibril aggregation.

The research team, led by Vikas Rana, Gyanesh Joshi and Ajay Thakur, obtained one- and two-year-old culms of Dendrocalamus asper, Bambusa tulda, Bambusa nutans, Melocanna baccifera and Bambusa bambos from the institute’s bambusetum in Dehradun, all cultivated under National Bamboo Mission guidelines. Culms were split and chipped into uniform pieces, and proximate chemical analysis was carried out using TAPPI standard methods. The analysis revealed that all five species carried high cellulose and comparatively low lignin, ash and silica contents — a favourable starting profile for pulping. Notably, Klason lignin ranged from 19.68 to 25.40 percent, with the lowest value recorded in one-year-old B. nutans and the highest in two-year-old B. bambos, confirming that younger bamboo is chemically predisposed toward easier delignification because secondary cell-wall lignification accumulates with age.

Before pulping, the chips underwent a simple hot-water pretreatment at 150 degrees Celsius for either 60 or 90 minutes, with a solid-to-liquor ratio of 1:5. This autohydrolysis step exploits the self-dissociation of water at elevated temperature: protonated water liberates acetyl groups from hemicellulose, creating a mildly acidic environment that hydrolyses the branched, low-degree-of-polymerization hemicellulosic sugars and washes them out of the biomass. The treatment extracted between 5.88 and 15.21 percent of hemicelluloses across samples, with longer reaction times consistently improving extraction. Crucially, the pretreatment also stripped out significant quantities of inorganic contaminants: ash fell from a range of 1.67 to 5.70 percent in untreated material to 0.44 to 1.79 percent after treatment, while silica dropped from 0.08 to 1.51 percent down to 0.03 to 0.44 percent. Because silica is notorious for causing scaling in digesters and evaporators and for inflating chemical consumption in recovery cycles, its removal markedly improves bamboo’s industrial credentials.

Pretreated chips were then kraft-cooked with an 18 percent active alkali charge expressed as sodium oxide and 20 percent sulphidity. Screened pulp yields ranged from 38.73 percent for two-year-old D. asper pretreated for 60 minutes to a standout 52.57 percent for one-year-old B. nutans under the same conditions — and every two-year-old species yielded less pulp than its one-year-old counterpart, a pattern the authors attribute to lower lignin and higher cellulose content in juvenile culms. Counterintuitively, pretreatment sometimes increased yield relative to untreated controls: two-year-old D. asper pretreated for 60 minutes delivered roughly 48.45 percent yield versus about 40.07 percent untreated, because removing water-soluble extractives and minerals beforehand improved chemical penetration and made delignification more selective, sparing cellulose from degradation. Kappa numbers, a proxy for residual lignin, fell across the board after pretreatment, with the lowest value of 9.14 achieved by one-year-old B. nutans pretreated for 60 minutes — the same sample that combined the highest yield with the easiest bleaching response.

That champion pulp was carried forward into an elemental chlorine-free D0EpD1 bleaching sequence, the industry’s preferred environmentally acceptable route. In the D0 stage, a 2 percent chlorine dioxide charge at 70 degrees Celsius and pH 4.5 oxidized and fractured residual lignin; the subsequent alkaline extraction stage, boosted with 1 percent sodium hydroxide and 0.5 percent hydrogen peroxide at pH 11, solubilized the oxidized fragments and accounted for the largest yield loss at 95.88 percent; a final 1 percent chlorine dioxide stage polished brightness. Kappa number declined stepwise from 5.30 to 4.50 to 3.80 across the sequence, and the finished pulp reached 92.3 percent brightness — comfortably above the 88 percent minimum typical of commercial dissolving grades.

X-ray diffraction analysis of the extracted alpha cellulose added a structural dimension to the story. Crystallinity indices for one-year-old samples ranged from 55.17 percent for B. tulda to 60.4 percent for B. nutans, and dipped slightly for all species in the second year, suggesting that maturation redistributes lignin and hemicelluloses within the cell-wall matrix and expands amorphous regions. Higher crystallinity in juvenile bamboo reflects tightly packed cellulose microfibrils, which the authors note could benefit strength-critical applications, while the more open structure of older material may suit chemically intensive processing. B. bambos and B. tulda held their crystallinity most stable over the two-year window, hinting at more uniform cellulose organization over time.

The final characterization of the B. nutans dissolving pulp read like a specification sheet: 93.70 percent alpha cellulose, 1.70 percent hemicellulose measured as pentosan, 0.81 percent lignin, 0.23 percent ash and 467 millilitres per gram intrinsic viscosity in cupriethylenediamine — squarely within the 400 to 600 millilitres per gram window considered desirable for downstream conversion. Ash was marginally above the roughly 0.15 percent typical of commercial pulps, but the overall profile matched or exceeded benchmarks reported for dissolving pulps from other bamboo species and from conventional wood sources.

Beyond the laboratory, the implications are economic and environmental. Bamboo attains most of its height within four months of sprouting and most of its biomass within eleven, meaning a harvest cycle dramatically shorter than the decades required for pulpwood plantations. Its regeneration after cutting can relieve pressure on natural forests, its tolerance of marginal soils opens degraded land to productive use, and the hemicellulose-rich liquors recovered during pretreatment could feed a biorefinery stream rather than a waste stream. For India — home to roughly 125 indigenous bamboo species yet still an importer of dissolving-grade pulp — the study offers a practical recipe: choose one-year-old B. nutans, pretreat with hot water at 150 degrees for an hour, kraft-cook, and bleach chlorine-free. The result is a renewable, domestically grown feedstock capable of anchoring the viscose, lyocell and cellulose-derivative industries of a circular material economy.

Subject of Research: Species- and age-dependent evaluation of bamboo feedstocks for sustainable dissolving-grade pulp production

Article Title: Evaluating bamboo species and age effects on dissolving grade pulp production for sustainable materials

Article References: Rana, V., Joshi, G., Thakur, A., Malik, S., Chauhan, J., & Chaudhary, U. (2026). Evaluating bamboo species and age effects on dissolving grade pulp production for sustainable materials. Discover Industrial Chemistry and Materials, 1(1), Article 6. https://doi.org/10.1007/s44508-026-00006-x

Image Credits: AI Generated

DOI: 10.1007/s44508-026-00006-x

Keywords: bamboo, dissolving pulp, Bambusa nutans, kraft pulping, hot water pretreatment, alpha cellulose, elemental chlorine-free bleaching, viscose rayon, crystallinity index, silica removal, sustainable materials, Forest Research Institute Dehradun