Decomposition Rate Research Articles

The microbial mechanism of maize residue decomposition under different temperature and moisture regimes in a Solonchak

Soil salinization becomes serious under climate change and human activities. Although the residue decomposition contributes lots to soil carbon storage and fertility, the decomposition process and microbial mechanisms on saline-alkali soils are still vague facing climate change. We measured the mass loss of residue (0, 4, 8, 15, 30, 60 and 90 days), CO2 emission (every two days), and the microbial community structure (0, 4, 15 and 90 days) by using the litter bag method, gas chromatography and high-throughput sequencing technology during the residue decomposition (90 days) in a saline-alkali soil from the Tarim River Basin, China under various temperatures (15 °C, 25 °C, 35 °C) and soil moisture levels (20%, 40%, 60% water holding capacity). The decomposition stage consisted of fast (0–15 days) and slow periods (15–90 days). Using the double exponential equation, the decomposition rates of labile and recalcitrant components, the labile component and cumulative CO2 emissions increased faster with increased moisture than with temperature. The Q10 was greater at 15–25 °C than at 25–35 °C, which increased with the increased soil moisture in the leaf but with decreased soil moisture in the stem at 15–25 °C. Proteobacteria increased from 0 to 15 days on leaves (25–43%) and stems (25–29%) and showed no changes thereafter. Proteobacteria increased with increased soil moisture but decreased temperature. Actinomycetes was the opposite and more abundant on the stem than on the leaf. Bacteroidetes increased after 15 days and increased with increased soil moisture. Firmicutes were the main bacterial groups at 0–15 days, but decreased at 15–90 days (leaf: 44 − 15%, stem: 49 − 13%). In conclusion, warming, especially 15–25 °C, contributes to the decomposition of stems and wetting, especially 20-40% WHC, contributes to that of leaves within the first 15 days, afterwards wetting played an important role. Our results could also provide the adopting strategies for residue return to increase the soil carbon content while decreasing CO2 emissions facing climate change.

Effects of Enzymatic Disintegration on the Decomposition of Organic Compounds During Methane Fermentation of Sewage Sludge

This paper presents the results of a study on the effect of lipase on the methane fermentation of sewage sludge. The process was conducted at 37 °C for 20 days for five sludge mixtures. Excess sludge inoculated with digested sludge constituted the control sample. The other four samples are the aforementioned mixtures with the addition of lipase in amounts representing 0, 1, 2, 3, and 4% (w/w) with respect to sludge dry weight. The organic matter decomposition rate was 27.1% in the control sludge and from 33.5 to 46.7% in the disintegrated sludge. During the digestion of the control sludge, the total amount of biogas was 5802 mL·L−1. In sewage sludge enzymatically disintegrated by lipase, there was an increase in biogas from 15 to 26%. In the disintegrated sludge, an almost complete (95–100%) reduction in E. coli and Salmonella spp. was achieved. Therefore, enzymatic disintegration can be an effective alternative to physical and chemical disintegration methods.

Molecular dynamic simulation study on the influence of heating rate on the thermal decomposition process of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).

To clarify the effect of heating rate on the thermal decomposition process of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), this study employs molecular dynamic simulations to investigate the thermal decomposition of TATB at heating rates of 20, 40, 60, and 80K/ps. The initial temperature is uniformly set to 300K, while the final temperature is set to 3000K. Results indicate that within the temperature range of 300-3000K, the thermal decomposition rate of TATB decreases with increasing heating rate, whereas the initial decomposition temperature of TATB increases, consistent with the experimental pattern. Within the studied temperature range, a lower heating rate results in a higher number of decomposition fragments, leading to more effective collision between active fragments, facilitating more effective collisions between active species, and leading to the formation of more stable products such as H₂O, CO₂, and N₂. Conversely, higher heating rates reduce the quantities of these stable products. This study enhances the understanding of TATB's thermal decomposition mechanism, providing valuable insights for its safe handling and application. METHODS: The Gaussian09 software was used to calculate the BDEs of TATB molecules, while the MD simulation using the ReaxFF-lg force field was performed by the LAMMPS package. Visualization and postprocessing were conducted using the OVITO software, and a custom script was developed to analyze the reaction products and frequencies.

In vitro biochemical features of cold plasma application in MCF-7 experimental breast cancer cells

Introduction. Low-temperature plasma is currently used in medicine, including cancer therapy. Plasma-activated biological solutions have already been proposed as potential reagents for cancer treatment. However, the biological effects in cells induced by exposure to cold plasma still remain unexplored. Investigation of the molecular mechanisms of the effects of cold plasma on cells is of great clinical importance for its clinical application. the aim of the present study was to evaluate the effect of cold plasma exposure on apoptosis, catalase activity, and malonic dialdehyde content in MCF-7 breast cancer cell cultures compared to 3T3 normal fibroblast cells. Material and Methods. MCF-7 mammary epithelial cells were used as research objects, and NIH/3T3 mouse embryonic fibroblast cells were used as controls. Cell suspensions were treated using low-temperature atmospheric discharge plasma with escaping electrons. Annexin V and propidium iodide were used to quantify cell line apoptosis. The content of malonic dialdehyde was determined by the developing coloration of its solution with 2-thiobarbituric acid at high temperature in acidic medium. The activity of catalase was estimated by the rate of decomposition of hydrogen peroxide for a certain time of incubation of the mixture. Results. It was found that irradiation of MCF-7 cell culture with plasma led to an increase in the content of malondialdehyde, the main product of lipid peroxidation. the increase in this parameter is an indicator of cell membrane damage and oxidative stress induced by irradiation. In addition, under the same irradiation regime, cold plasma showed a stimulating effect on the culture of 3T3 cells, while on the MCF-7 culture, on the contrary, it stimulated the activation of apoptosis and cell death. Conclusion. In the present study, we found that exposure of tumor and normal cells to cold plasma promotes apoptosis activation. Catalase and MDA activity have been shown to be significant markers capable of assessing the intensity of oxidative stress.

Declines in carbon and nitrogen release from decomposing litter under elevated CO2 in terrestrial ecosystems

Abstract Atmospheric carbon dioxide (CO2) concentrations have been increasing dramatically due to human activities and land use changes, and the CO2 fertilization effect significantly increases global net primary productivity (NPP). However, whether the decomposition of surplus litter input on the soil surface is facilitated by elevated CO2 (eCO2) across a broad range of terrestrial ecosystems is not fully understood. We compiled 227, 85 and 131 paired observations (with and without eCO2) for litter mass loss, carbon (C) and nitrogen (N) release, respectively, during litter decomposition to assess the fate of decomposing litter and C and N release under eCO2 across terrestrial ecosystems. Litter mass loss was decreased by 4.46%, and C and N release were significantly reduced by 6.70% and 3.36%, respectively, under eCO2. This eCO2 effect on litter mass loss was greater in forests (decreased by 7.22%) than in croplands and grasslands. In forests, eCO2 had a greater effect on the decomposition rate of broadleaved than coniferous litter, and root litter was more sensitive than leaf and stem litter. Changes in litter lignin concentration and edaphic factors under eCO2 contributed to these differences in litter decomposition. Greater decreases in litter mass loss and C and N release were found after longer time (6-12 months) than short-term (less than 6 months) CO2 enrichment. A possible consequence is that more litter accumulates on soil surface without being decomposed due to eCO2 in terrestrial ecosystems over longer time periods, resulting in a negative loop in biogeochemical cycles with increasing atmospheric CO2 concentration.

Root decomposition and nutrient dynamics in multifunctional forage‐biomass buffer‐strip systems

AbstractPerennial crops are thought as a solution for enhancing food security and providing ecosystem services under a changing climate, including forage‐biomass production, reduced erosion and nutrient leaching, and soil C accumulation. However, the drivers of root decomposition and C allocation in perennial multifunctional forage‐biomass buffer‐strips as affected by fertility management are poorly elucidated. Thus, study objectives were to assess root decomposition and soil CO2 efflux on switchgrass (Panicum virgatum L.), eastern gamagrass (Tripsacum dactyloides L.), silphium (Silphium integrifolium Michx.), and intermediate wheatgrass Kernza (Thinopyrum intermedium [Host] Barkworth & D.R. Dewey) treated with poultry litter (PL) relative to the unfertilized control. Root mass loss was greatest for silphium, owing to low neutral and acid detergent fibers and lignin contents (6%) relative to the other species (16%–25%). Root‐C loss was the greatest for intermediate wheatgrass (IW), mostly driven by hemicellulose degradation. Low root mass, surface area, and volume likely enhanced root decomposition for silphium and IW. Root mass loss and C, N, and P mineralization for novel perennial buffer‐strip species were greater in PL plots. Soil organic C stocks were mostly similar across forage‐biomass species × amendment combinations. Silphium‐PL had 27%–50% greater SOC stocks after 4 years, owing to higher root sloughing and C inputs to soil. Root decomposition rates were primarily affected by root chemical composition and morphology, while soil CO2 efflux was driven by soil moisture and temperature. Greater root sloughing, C inputs, and nutrient cycling showcase the potential for C storage and multiple purposes of novel perennial buffer‐strips.

Nitrogen Deposition Enhances Interactions Between Litter Types During the Early Stage of Decomposition

ABSTRACTNitrogen deposition can alter the interactions between litter types during their decomposition, and thus affect material cycling and ecosystem stability. However, it is unclear how the differences in the initial chemical properties of litter mixtures affect their response to nitrogen deposition. In this study, we investigated three litter mixtures: high quality–high quality (Robinia pseudoacacia–Stipa grandis, Rp‐Sg, mixed form F1), high quality–low quality (Rp–Setaria viridis, Rp‐Sv, F2), and low quality–low quality (Artemisia gmelinii–Sv, Ag‐Sv, F3). Each of the litter types can be found in Rp plantations in the Loess Hilly Region, China. We subjected the litter mixtures to nitrogen deposition treatments (0 and 4–12 g·m−2·a−1) in a 326‐day indoor decomposition experiment. Decomposition parameters of each litter type in monospecific and mixed decomposition were compared to investigate the interactions between litter types under nitrogen deposition. The results indicated that, in the early stage of mixed decomposition, litter types of similar substrate quality did not affect the decomposition of each other (i.e., in the F1 and F3 mixtures). In contrast, the decomposition of low‐quality litter (Sv) was accelerated by that of high‐quality litter (Rp) when there was no nitrogen deposition. The overall degree of the mutual effects (Rinter,t) for the litter decomposition rate in F1, which has an overall higher quality, increased and then decreased with increasing nitrogen deposition; whereas the Rinter,t for the litter decomposition rate in F2 and F3, which have an overall poor quality (p < 0.05), increased continuously. In general, nitrogen deposition increased the interactions between litter types during the early stage of mixed decomposition. Given that most interactions were synergistic, this effect of nitrogen deposition may alleviate its inhibitory effects on litter decomposition in the study region.

Investigation on the Thermal Decomposition Behavior of Molybdenum Trioxide Precursor.

The ultrafine MoO3 powders were prepared by the combination of centrifugal spray drying and calcination in this work. The thermal decomposition behavior of the spherical precursor was studied. The phase constituents, morphologies, particle size, and specific surface areas of MoO3 powders were characterized at different temperatures. It is found that the decomposition of the precursor is subjected to five stages, and forms different intermediate products, including (NH4)8Mo10O34, (NH4)2Mo3O10, (NH4)2Mo4O13, h-MoO3, and the final product α-MoO3. Moreover, the decomposition rate equation is established based on the thermal decomposition kinetic parameters of the precursor. With an increase in decomposition temperature, the morphology changes from unclear boundary particles to dispersed flake particles, and the flaky particles exhibit larger sizes, higher crystallinity, and better dispersion, which can be attributed to the mass transfer of gaseous MoO3 products. Additionally, the MoO3 particle size decreases progressively, and the specific surface area increases and then decreases. At 500 °C, it can achieve ultrafine flaky MoO3 powder with the size of thick sheets, with a thickness of about 300 nm and a length of about 1-3 μm. This research can offer an innovative strategy for preparing ultrafine MoO3 powder.

Biocompatibility of electrospun PVA-based nanocomposite with chemical vapor deposition-derived graphene monolayer

The biocompatibility of electrospun PVA with monolayer graphene obtained by chemical vapor deposition (PVA/CVD-grown MLG) nanocomposite was investigated. The properties of PVA/CVD-grown MLG nanocomposite were compared with those of electrospun PVA mat. Raman analysis confirmed the presence of graphene monolayer on PVA. Although no significant changes in tensile properties were observed, the electrical conductivity increased from 0.1 (PVA mat) to 0.4 μS/cm (PVA/CVD-grown MLG). Thermal stability was also increased, as evidenced by the higher onset temperature and temperature of maximum decomposition rate determined by TGA. The contact angle decreased slightly, which resulted in higher PBS absorption and degradation of the nanocomposite. Water vapor transmission rate (WVTR) decreased from 40 (PVA mat) to 37 g/m2 h (PVA/CVD-grown MLG). Cell culture studies showed better cell viability, population, and growth in the case of PVA/CVD-grown MLG nanocomposite due to improved physical, chemical and mechanical properties.

Multiple stressor effects act primarily on microbial leaf decomposers in stream mesocosms.

At the global level, stream ecosystems are influenced by multiple anthropogenic stressors such as eutrophication, habitat deterioration, and water scarcity. Multiple stressor effects on stream biodiversity are well documented, but multiple stressor effects on stream ecosystem processes have received only limited attention. We conducted one mesocosm (stream channel) and one microcosm (feeding trial) experiment to study how combinations of reduced flow, increased nutrient concentrations, and increased fine sediment coverage would influence fungal and macroinvertebrate decomposer assemblages and their active contribution to leaf decomposition. In the stream channels, increased fine sediment coverage significantly reduced fungal biomass, occurrence frequencies of most aquatic hyphomycete species, and microbial leaf decomposition rates compared to untreated controls. Macroinvertebrate-induced leaf decomposition rates were mainly correlated to total fungal biomass and community composition. Neither increased nutrient concentrations, nor reduced flow conditions significantly influenced leaf decomposer communities or decomposition rates. The feeding trials revealed significantly reduced leaf consumption in the freshwater amphipod Gammarus pulex when feeding on leaf material from treatments with increased fine sediment coverage in the mesocosm experiment. When offered a food choice between sterile, unconditioned leaf material and leaf material from treatments with increased fine sediment coverage, G. pulex foraged mainly on sterile material. This study showed that increased fine sediment coverage can alter the flux of energy and material in the detrital food chain through bottom-up regulation of leaf conditioning by fungal decomposers. Our results suggest that increasing attention should be given to mitigating fine sediment transport and deposition in stream systems to preserve ecosystem functioning within the detrital food chain.

Functional Traits and Species Identity Drive Decomposition Along a Successional Gradient in Upper Andean Tropical Forests

ABSTRACTLeaf litter decomposition constitutes one of the most vital processes for maintaining productivity and carbon release in ecosystems. However, this remains one of the least understood processes in upper Andean tropical forests (UATF), a highly diverse ecoregion that has undergone extensive transformation over the centuries. In this study, we aimed to determine the relationships between decomposition rates of leaf litter, leaf functional traits, and microclimatic conditions along a successional gradient of UATF. We also tested the “after‐life effect” by analyzing changes between green and senescent leaves. We performed a fully reciprocal translocation experiment with 15 representative species of UATF in a set of 14 permanent plots by using 2520 litterbags distributed across 42 experimental units (three litterbeds per plot), over 1.5 years, with four harvesting times (3, 6, 12, and 18 months). Chemical and physical traits were measured in green and senescent leaves to identify the best predictors of decomposition and to analyze the “after‐life effect.” We found that functional traits and species identity drive litter decomposition in UATF, rather than succession and microclimatic conditions of soil moisture and temperature. The relative importance of traits was prevalent in all stages of decay, despite being stronger in the early phases. Although we found an “after‐life effect” of green leaves in decomposition, changes in chemical composition from green to senescent leaves indicated substantial nitrogen resorption, which is a limiting resource in tropical montane forests. With the increasing landscape transformation in UATF, changes in plant species composition could have profound impacts by altering decomposition rates, nutrient cycling, and global carbon storage.

Effects of Polymer Matrix and Atmospheric Conditions on Photophysical Properties of a Cesium Lead Bromide (CsPbBr3) Perovskite Quantum Dot.

Understanding the environment-dependent stability and photoluminescence (PL) properties of advanced perovskite materials remains a challenge with conflicting views. Herein, we investigated the influence of the host matrix (poly(methyl methacrylate) (PMMA) and polystyrene (PS)) and atmospheric conditions (ambient and N2) on the PL properties of a CsPbBr3 perovskite quantum dot (PQD) using single-particle spectroscopy. Despite the same PL blinking mechanism, the PL properties of the PQD were considerably affected by the environmental conditions. The charge trapping and detrapping rates of the PQD were lower and higher, respectively, under ambient atmosphere than under N2 owing to surface defect passivation by oxygen. The frequency and rate of PQD decomposition were higher in the PMMA matrix than in the PS matrix under an ambient atmosphere. PS achieved superior PQD encapsulation owing to its higher affinity toward hydrophobic surface ligands because of its aromatic rings, thereby protecting the PQD surface from moisture and thus inhibiting decomposition.

Analisis Erodibilitas Tanah untuk Budidaya Talas Beneng Berkelanjutan berdasarkan Elevasi

Taro Beneng holds significant potential to enhance food security and economic value, particularly in the Banten region. This study aimed to analyze soil erodibility values across Taro Beneng cultivation areas in Talaga Warna, Juhut, and Kaduengang villages to support sustainable land management and optimize crop yields. Conducted in 2024, the research employed a survey method with soil erodibility analysis based on the Wischmeier and Smith (1978) formula, considering parameters such as soil texture, structure, organic matter, and permeability. Thirty soil samples were collected across three elevation zones to capture variability, and the erodibility (K) values were calculated using Microsoft Excel, with spatial mapping conducted via ArcGIS. Results indicate that organic matter content increases with elevation due to climatic factors influencing decomposition rates. Soil texture ranges from sandy clay loam in Talaga Warna and Juhut to loamy sand in Kaduengang, reflecting the geographical diversity of the Mount Karang region. Soil structure varies from granular to coarse, with differing permeability levels contributing to varied erodibility risks. The highest soil erodibility values were recorded in Talaga Warna and Juhut (K = 0.49), indicating high erosion susceptibility, while Kaduengang exhibited the lowest value (K = 0.36), suggesting more stable soil conditions. These findings highlight the spatial variability of soil erosion risks in Taro Beneng fields, offering insights to guide targeted soil conservation practices. By addressing areas with higher erosion risks, this study provides practical recommendations for sustainable land management to support Taro Beneng cultivation and ensure long-term soil health in the region.

Method for Effective Increasing the Decomposition Rate of Ammonium Perchlorate in Solid Rocket Fuel

Method for Effective Increasing the Decomposition Rate of Ammonium Perchlorate in Solid Rocket Fuel

Kinetics of decomposition of 1,1-diamino-2,2-dinitroethylene (FOX-7). 6. The induction period at the early stages of the reaction in the solid state

The kinetics of thermal decomposition of FOX-7 compound at 155 °C under semi-open conditions in vessels with a volume of V = 0.8–0.9 cm3 in an air atmosphere and the degree of filling of the vessel with substances m/V = 0.03–0.72 g/cm3 has been studied by gravimetric method. It was found that at the largest m/V, an induction period is observed at the early stages of the reaction, during which the rate of mass loss of the sample is ten times less than the rate of decomposition of FOX-7 in the solid phase. With a decrease in m/V, the induction period is shortened and at m/ V = 0.04 g/cm3 disappears altogether. The appearance of the induction period is due to the fact that nitronic acid, which is the only product of the first stage of decomposition of FOX-7, is well adsorbed on the surface of FOX-7 crystals. At the same time, it almost completely loses its reactivity. As a result, until the end of the adsorption process, the decomposition of FOX-7 proceeds without the formation of gaseous products, and the reaction rate is not fixed by the gravimetric method suitable for studying the kinetics of the reaction at the early stages of decomposition FOX-7.

Patterns in coarse root decomposition of woody plants: effects of climate, root quality, mycorrhizal associations and phylogeny.

Coarse roots represent a globally important belowground carbon pool, but the factors controlling coarse root decomposition rates remain poorly understood relative to other plant biomass components. We compiled the most comprehensive dataset of coarse root decomposition data including 148 observations from 60 woody species, and linked coarse root decomposition rates to plant traits, phylogeny and climate to address questions of the dominant controls on coarse root decomposition. We found that decomposition rates increased with mean annual temperature, root nitrogen and phosphorus concentrations. Coarse root decomposition was slower for ectomycorrhizal than arbuscular mycorrhizal associated species, and angiosperm species decomposed faster than gymnosperms. Coarse root decomposition rates and calcium concentrations showed a strong phylogenetic signal. Our findings suggest that categorical traits like mycorrhizal association and phylogenetic group, in conjunction with root quality and climate, collectively serve as the optimal predictors of coarse root decomposition rates. Our findings propose a paradigm of the dominant controls on coarse decomposition, with mycorrhizal association and phylogeny acting as critical roles on coarse root decomposition, necessitating their explicit consideration in Earth-system models and ultimately improving confidence in projected carbon cycle-climate feedbacks.

Legumes and cereal crop rotation effect on soil fertility under selected agronomic practices in central farming region, Mongolia

The experimental study aimed at identifying the effects on soil fertility and resources using five different treatments, fallow, non-cultivated land, serial plants, leguminous plants, and grass, was conducted in a central agricultural region of Mongolia. The findings highlight the beneficial effects of cooperative agriculture for food and fodder on the restoration of soil fertility and its resulting useful effect on wheat crop yield. To ensure the stability of soil fertility in the central agricultural region, the key results of the suggest that mobile macro element nitrogen in the soil increased by 45-75.9 per cent over a 3-year rotation with spring soft wheat as the major crop grown along with leguminous plants. Furthermore, the implementation of a two-year rotation of Melilotus albus as intercropping for fodder and food purposes has been found to enhance the rate of soil cellulose decomposition. Furthermore, it has been observed that the continuation of favorable weather conditions and availability of moisture directly correlate with the extent of cellulose decomposition. The aggregate structure of the soil with a diameter of 1-3 mm, which is crucial for growing perennial grass (Agropyron cristatum), is improved by 11.87 per cent to enhance the field's soil structure and reduce erosion. In our research, it was found that legumes have a high protein content and are important role in meeting the needs of livestock and human food, while enriching the soil with nitrogen and increasing the yield of other crops. However, the practical importance of our research lies in the fact that it was established that perennial plants improve the structure of the soil. Legumes, according to our research, are rich in protein and contribute significantly to the provision of food for humans and livestock, as well as to the enhancement of soil nitrogen levels and the growth of other crops. Nevertheless, our study holds practical significance because it proves that grasses enhance the soil's structure as well.

Investigation of Calcium Phosphate-Based Biopolymer Composite Scaffolds for Bone Tissue Engineering.

We present a novel method for preparing bioactive and biomineralized calcium phosphate (mCP)-loaded biopolymer composite scaffolds with a porous structure. Two types of polymers were investigated as matrices: one natural, cellulose acetate (CA), and one synthetic, polycaprolactone (PCL). Biomineralized calcium phosphate particles were synthesized via wet chemical precipitation, followed by the addition of organic biominerals, such as magnesium gluconate and zinc gluconate, to enhance the bioactivity of the pure CP phase. We compared the morphological and chemical characteristics of the two types of composites and assessed the effect of biomineralization on the particle structure of pure CP. The precipitated CP primarily consisted of nanocrystalline apatite, and the addition of organic trace elements significantly influenced the morphology by reducing particle size. FE-SEM elemental mapping confirmed the successful incorporation of mCP particles into both CA and PCL polymer matrices. Short-term immersion tests revealed that the decomposition rate of both composites is slow, with moderate and gradual ionic dissolution observed via ICP-OES measurements. The weight loss of the PCL-based composite during immersion was minimal, decreasing by only 0.5%, while the CA-based composite initially exhibited a slight weight increase before gradually decreasing over time.

Rapid and well-controlled degradation of polylactic acid materials with bio-based GEL(pectin/α-cellulose/SiO2/CaCl2).

Polylactic acid (PLA) has been a subject of considerable interest as a degradable polymer. However, the degradation process is slow and uncontrollable. In this work, controlled degradable PLA/bio-based GEL (pectin/α-cellulose/SiO2/CaCl2) hydrophilic plasticizer composite material was successfully prepared by solution blending process. The bio-based GEL was proven to have strong water absorption properties and the ability to improve and regulate the degradation performance of PLA. The results declared that the addition of 5% GEL and 15% polyethylene glycol (PEG) to the PLA composites resulted in a degradation degree of 83% within 12h in an alkaline solution. And the rate represents a 21.2-fold increase in speed compared to pure PLA material. Under neutral and acidic conditions, the degradation degree of the modified composites was approximately 169 times faster than that of pure PLA. Meanwhile, the tensile strength of PLA composites decreased from 44.8MPa to 16.7MPa, but the elongation at break increased from 5.8% to 172% compared to pure PLA. Furthermore, the initial decomposition temperature and maximum thermal decomposition rate temperature of PLA composites were found to be reduced. The controlled degradation of PLA composites was accomplished through the regulation of GEL content. The hydrolysis degradation process under different pH laid a foundation for the pretreatment process of soil microbial degradation of PLA. The mechanism suggested that the GEL created a large number of pores on the surface and inside the material within an extremely short period of time, providing ample opportunities for soil microorganisms to invade.

Fluorescence of various buried fresh and fresh-frozen-thawed tissue types up until the point of active decay: a human taphonomy study.

Forensic taphonomy is the study of postmortem changes of human remains for the purpose of answering legal investigative questions. Many variables can affect the pattern and rate of decomposition of remains, posing challenges for taphonomic studies and estimation of the postmortem interval. Given the gap in knowledge regarding the suitability of using frozen remains to extrapolate conclusions to fresh material, investigating the effects of freeze-thaw cycles followed by burial on human remains is vital for forensic practice and taphonomic research. This study explored the impact of a freeze-thaw cycle and subsequent burial on human tissue decomposition under semi-controlled field conditions. Fresh and fresh-frozen-thawed hands were buried at the Amsterdam Research Initiative for Sub-surface Taphonomy and Anthropology for 31.7 to 340.4 accumulated degree days. Decomposition was assessed using fluorescence measurements targeting protein and fluorescent oxidation products, and broader excitation-emission matrix measurements in skin, adipose, and muscle tissue. Decomposition trends varied primarily by treatment group: fresh samples generally aligned with expectations that protein levels would decrease over time while fluorescent oxidation products increased, whereas fresh-frozen samples deviated significantly from these expectations. Significant differences were found between protein and fluorescent oxidation products levels of fresh and fresh-frozen tissue at corresponding time points, indicating this method's potential in determining sample state. However, fluorophore peak monitoring in excitation-emission matrices did not prove useful in establishing decomposition trends or potentially distinguishing between sample states. Despite limitations inherent to pilot and human taphonomy studies, this study clearly demonstrates that differences exist in the decomposition of fresh and fresh-frozen tissue, and that these trends vary slightly by tissue type. We therefore conclude that frozen material cannot be considered a proper substitute for fresh tissue regarding taphonomic processes, and the methods used in this study show promise in being used to differentiate between pre-decomposition treatments.