Degree Of Degradation Research Articles

Promotion or Inhibition Effects of Exogenous Glutathione-Degraded Amino Acids on the Formation of 2,3-Butanedione and Pyrazines via Varied Pathways of Interaction with α-Dicarbonyl Compounds Derived from N-(1-Deoxy-d-xylulos-1-yl)-alanine.

The contribution of glutathione (GSH) and free amino acids degraded from GSH to the generation of pyrazines and 2,3-butanedione was illustrated during their interaction in the thermal treatment of the Amadori compound of alanine and xylose (ARP). GSH-degraded amino acids, glutamic acid (Glu), cysteine (Cys), and glycine (Gly), but not pyroglutamic acid (pGlu), could effectively capture α-dicarbonyls to facilitate the formation of pyrazines when ARP was heated with GSH. Deoxypentosones, the precursors of 2,3-butanedione, were largely consumed in the ARP-GSH model by the interaction with GSH and its degradative Cys compared with the ARP model. The addition of GSH and deoxypentosones inhibited the further degradation of deoxypentosones, resulting in less formation of 2,3-butanedione and other α-dicarbonyl compounds. Meanwhile, the reaction between GSH-degraded Cys and deoxypentosones to form sulfur-containing compounds such as thiols accelerated the consumption of deoxypentosones; thereby, the formation of 2,3-butanedione was severely interfered. However, this inhibition was compensated for by the GSH-degraded Gly through the addition between Gly and MGO and the subsequent deamination. The involvement of exogenous GSH could simultaneously boost the yields of 2,3-butanedione and pyrazines compared with those of ARP heated alone. As the degree of GSH degradation strengthened in the ARP-thermal-degraded GSH models, the yields of both pyrazines and 2,3-butanedione steadily increased.

Analysis of Thermal Aging Influence on Selected Physical and Mechanical Characteristics of Polyaddition and Polycondensation Poly(dimethylsiloxane).

The aim of the study was to determine the effect of accelerated thermal aging on the properties of selected poly(dimethylsiloxanes) (PDMS) differing in viscosity and hardness. This was related to the potential application for specialist casting molds with complex geometry. Four polyaddition silicones and two polycondensation ones were selected. As part of the work, tensile strength, hardness, density, roughness, and Dynamic Mechanical Analysis (DMA) and Fourier Transform Infrared Spectroscopy (FTIR) were tested, which allowed us to determine the degree of degradation of the analyzed materials subjected to thermal aging at a temperature of 150 ± 2 °C. The aging temperature was conditioned by the parameters of the materials that can be cast into molds made of poly(dimethylsiloxanes) e.g., with polymer resins, for which the exothermic peak ranges from 100 to 200 °C depending on the volume. It was observed that the initial Shore A hardness value affects parameters such as tensile strength or the amount of value change (its increase or decrease) after thermal aging. It can also be concluded that for polyaddition PDMS, the viscosity of the material has an effect on the size of the relative elongation value after thermal aging.

Establishing a quantitative assessment methodology framework of water conservation based on the water balance method under spatiotemporal and different discontinuous ecosystem scales

Water conservation (WC) is an essential terrestrial ecosystem service that mitigates surface runoff and replenishes groundwater, which has received considerable attention under the dual pressures of climate change and human activity. However, there is insufficient understanding of the trends in WC changes on temporal (annual, monthly, daily), spatial, and ecosystem scales. This study proposed a quantitative assessment methodology framework (QAMF) for analyzing the spatiotemporal variation of WC under different discontinuous ecosystems. The QAMF mainly used models and methods such as the hydrological model (SWAT), calibration and uncertainty program (SWAT-CUP), WC calculation formula (water balance method), and spatial analysis method (empirical orthogonal function and wavelet analysis). It was applied to the source region of the Yellow River (SRYR), where the ecological landscape pattern underwent varying degrees of degradation, and WC capacity decreased. The results show that: Firstly, the constructed SWAT in the SRYR had high accuracy, and the proposed formula for calculating WC was suitable for multi-temporal scale analysis of WC in spatially distributed discontinuous basins. Secondly, the annual and monthly WC were respectively 81.00–184.13 mm and −28.58–107.64 mm, and daily WC was positive during extreme precipitation periods and negative during dry periods. The regulating effect of WC was fully reflected on the daily scale, partially reflected on the monthly scale, and absent on the annual scale. Third, the crucial WC area was mainly distributed in the southeast, and there was a significant primary yearly cycle of WC in the SRYR. Finally, different ecosystems exhibited different WC capabilities, and protecting the diversity of ecosystems played an essential role in maintaining and improving the WC function in the SRYR. This project has great scientific significance and technological support for scientifically evaluating the WC capacity in the SRYR.

Evolutionary power spectral density study of the earthquake-induced dynamic irregularity based on short-time Fourier transform

The stiffness degradation of the track-bridge system under earthquake is the main reason for the deterioration of track dynamic smoothness. In order to investigate the dynamic smoothness performance of the track surface of the track-bridge system after earthquake. In this paper, a nonlinear time analysis of ballastless track-simply supported bridge system under transverse random earthquakes is carried out, and the degradation mode and degradation degree of each key component of the track-bridge system after transverse earthquakes are investigated. Based on the post-earthquake stiffness of each component, a train-track-bridge system considering earthquake-induced stiffness degradation is established. The sample library of earthquake-induced dynamic irregularity is constructed by additional deformation of rails, and the power spectral density of the earthquake-induced dynamic irregularity is studied. Based on the short-time Fourier transform irregularity inversion technique, the earthquake-induced dynamic irregularity characteristic curve based on the probability guarantee rate is proposed, and the effects of train operating speed and ground vibration intensity on the earthquake-induced dynamic irregularity characteristic curve are investigated. The research results show that: The transverse stiffness degradation of the bearings and piers of the track-bridge system is the most obvious during an earthquake, and the stiffness degradation degree of the middle piers is greater than that of the side piers. The stiffness degradation degree of the track-bridge system rises significantly with increasing PGA, while the variability of stiffness degradation of the middle and side piers drops. The most significant earthquake-induced dynamic irregularity sample is the track alignment irregularity. Low-frequency components dominate the evolutionary power spectral density corresponding to track dynamic irregularity, and the amplitude of the power spectral density reduces considerably with increasing spatial frequency. The vehicle speed has little effect on the earthquake-induced track dynamic irregularity. The irregularity amplitude grows significantly with increasing damage degree. The results indicated that the stiffness degradation damage degree of the track-bridge system under earthquake can be quantified by constructive earthquake-induced track dynamic irregularity.

Effect of high-stress level loads on the fatigue performance of GFRP-RC beams

GFRP (Glass fiber reinforced polymer) reinforced concrete (GFRP-RC) structures are often used in harsh engineering environments to replace steel bars to resist environmental corrosion. Due to the low fatigue stiffness of the GFRP-RC structure, the structure is prone to failure due to excessive fatigue deformation after experiencing high-stress level loads such as tsunamis and earthquakes. In order to further study the characteristics of the mechanical performance of GFRP-RC beams under high fatigue stress levels, this paper carried out fatigue tests on 10 GFRP-RC beams at fatigue stress levels (S) of 0.85, 0.70, 0.65, and 0.60. The results show that the fatigue stress level can affect the failure mode of GFRP-RC beams, and high-stress loading is prone to inclined section failure. Otherwise, vertical cracking failure will occur. Increasing the fatigue stress level will not affect the damage growth rate during the stable stage of fatigue. However, it will exacerbate the accumulation of structural damage and the degree of fatigue stiffness degradation. In addition, the applicability of three existing fatigue deflection prediction models in GFRP-RC structures was also checked by experimental data, and it was found that only the CEB-FIP model had a higher accuracy.

Performance and damage states assessment of thin-walled steel bridge piers with end-corrosion under earthquake loading

End-corrosion is typical damage to steel bridge piers, which will reduce the seismic performance. Unlike overall uniform corrosion, end-corrosion results in more complex stresses on bridge piers, however, there are few related studies. This study aims to analyze the mechanical performance of corroded bridge piers and to establish a method for evaluating the seismic damage status of steel piers considering circumferential uniform end-corrosion. Firstly, the effect of corrosion parameters on key performance points of bridge piers is quantitatively analyzed using the validated finite element model. The calculation method of critical displacement value corresponding to different damage states of the end-corroded bridge pier is proposed. A high-precision fiber beam element analysis model is developed to simultaneously consider the effects of end-corrosion and shear stiffness variation. The results show that the degradation degree of yield displacement of the end-corroded bridge pier is relatively small. In contrast, the ultimate displacement, capacity point displacement and bearing capacity are significantly affected by corrosion parameters, and the degradation degree after corrosion can reach more than 30%. The pier damage ratio formula proposed in this study can accurately describe the degradation of the ultimate value, and the calculation error is almost controlled within 15%. The multi-node variable section (MNVS) fiber beam model proposed in this study has higher analysis accuracy, which can be improved by more than 16% compared with the traditional fiber beam model. In addition, the accuracy of the MNVS model in the dynamic analysis is verified by inputting the seismic records under three site conditions. Finally, considering the characteristics of end-corrosion, an evaluation method and procedure for seismic damage status of the steel pier with end-corrosion is established.

Swelling damage evolution of argillaceous slate in a water-rich environment

The swelling of rock is a key issue in engineering. With large infrastructure construction trending towards complex geological conditions, an increasing number of projects could suffer from soft-rock swelling. To solve this problem, an understanding of the evolution of damage occurring during the swelling process is essential. Argillaceous slate is a typical metamorphic rock and shows strong swelling characteristics in a water-rich environment due to its abundance of hydrophilic minerals. In this paper, argillaceous slate was selected as the research object. The evolution of damage in argillaceous slate during swelling was explored via laboratory tests that included swelling characteristic tests, soft-rock needle penetration tests and scanning electron microscope tests, and damage theory. The research findings reveal that the slate swelling process in a water-rich environment can be divided into three stages, with the swelling rate being highest in the early stage of the tests, then slowing over time and finally stabilizing. However, the strength of the argillaceous slate decreased rapidly in the early stage, and the degradation rate was generally slow in the later stage. After water absorption, the clay mineral particles begin to expand and the microscopic structure of the argillaceous slate becomes complicated, with the pore area increasing and the pore diameter decreasing. A low degree of microscopic damage was found to induce a high degree of macroscopic mechanical degradation. In addition, the damage mechanism that occurs during argillaceous slate swelling is discussed in this paper from both a microscopic and a macroscopic perspective. Indeed, a relationship between macroscopic mechanical degradation and microscopic damage to argillaceous slate was established that can provide theoretical support for further research on soft-rock swelling characteristics: the microscopic damage drives the macroscopic mechanical degradation.

Chemical Corrosion-Water-Confining Pressure Coupling Damage Constitutive Model of Rock Based on the SMP Strength Criterion.

Aiming at the problem of chemical-mechanics-hydro (C-M-H) action encountered by rocks in underground engineering, chemical damage variables, water damage variables, and force damage variables are introduced to define the degree of degradation of rock materials. Stone is selected as the sample for acid corrosion treatment at pH 3, 4, and 7, and a chemical damage factor is defined that coupled the pH value and duration of exposure. Then based on the spatial mobilized plane (SMP) criterion and the Lemaitre strain equivalence hypothesis, this research develops a constitutive model considering rock chemical corrosion-water-confining pressure damage. The proposed damage constitutive model employs the extremum method to ascertain the two Weibull distribution parameters (m and F0) by theoretical derivation and exhibits satisfactory conformity between the theoretical and experimental curves. The damage constitutive model can be consistent in the stress-strain characteristics of the rock triaxial compression process, which verifies the rationality and reliability of the model parameters. The model effectively represents the mechanical properties and damage characteristics of rocks when subjected to the combined influence of water chemistry and confinement. The presented model contributes to a better understanding of tangible rock-engineered structures subjected to chemical corrosion in underwater environments.

Experimental and numerical research on the static behavior of locally corroded OSBD

Corrosion can accelerate the deterioration of the mechanical properties of orthotropic steel bridge decks (OSBDs), seriously affecting the service safety of steel bridges. In this paper, thirty Q345C steel and four OSBD specimens with various corrosion levels are designed to investigate the effect of corrosion on the static behavior of OSBDs. Then, corrosion damage and its influence on mechanical properties are explored by static loading experiments. The constitutive model for Q345C steel is built considering the impact of corrosion. Finally, a numerical analysis considering geometric initial defects is employed to compare the effect of corrosion location on bearing capacity degradation. It is observed from the tested results that the corrosion led to the failure mode of Q345C steel changing from plastic failure to brittle failure. The ultimate bearing capacity of specimens with a local corrosion rate of 7.92%, 12.05%, and 16.24% decreased by 11.08%, 14.45%, and 17.82%, respectively. Corrosion leads to stress concentration in the top plate area, causing local instability of the structure. The degradation degree of the bearing capacity of the top plate is greater than that of the U-rib corrosion corresponding to the same corrosion conditions.

Understanding the Stress Testing Characteristics of Apixaban, Structural Elucidation of a Novel Degradation Impurity, and Stability-Indicating Method Development for Quantification of Related Substances.

People who have non-valvular atrial fibrillation may benefit from taking a new oral anticoagulant called apixaban, which has recently been given the green light by the U.S. Food and Drug Administration. During stress testing, apixaban was found to have a high degree of degradability when subjected to both acidic and basic conditions, and one significant unknown impurity was observed in addition to the major known impurities. Our aim is the isolation and characterization of degradation product observed in stress/forced degradation studies, and also the development of a single HPLC method that is both reliable and accurate for quantifying all 10 related impurities of apixaban. Preparative HPLC was used to isolate the degradation product, and 1H NMR, 13C NMR, and MS were used to elucidate the structure of the product. Additionally, a single reverse-phase (RP) HPLC method was developed for quantification of all related impurities of apixaban. Based on the spectral characterization data, the identified unknown degradation impurity was found to be a pH-independent hydrolysis degradation impurity of apixaban. The developed method is specific, linear, accurate, robust, and rugged. The isolated and characterized impurities were the same as those found during stress testing. The developed method has been validated for its intended purpose in accordance with the regulatory requirements that were outlined. The unknown impurity is a new apixaban degradation impurity that helps us understand its toxicity. The scientific community will benefit from the developed analytical method information as it relates to understanding drug product impurity profiling.

Influence of Fire Exposition of Fibre-Cement Boards on Their Microstructure.

The diagnostics of materials, elements and structures after fire exposure are very complicated. Researchers carrying out such diagnostics encounter difficulties at the very beginning, e.g., how to map fire conditions. In this publication, the authors focused on the analysis of the fibre-cement composite used as facade cladding. The fibre-cement boards are construction products used in civil engineering. The fibre-cement boards are characterised by two phases: the matrix phase and the dispersed phase. The analysis of fibre-cement composite was performed using non-destructive methods. The use of non-destructive methods in the future will allow for the analysis of facades after fires without the need to obtain large elements, which will significantly reduce costs while increasing safety. The aim of the work was to determine internal changes in the microstructure of fibre-cement boards after exposure to fire. The degraded samples were compared with reference samples in the evaluation of the microstructure. An analysis was performed using a scanning electron microscope, images of backscattered electrons (BSE) and maps obtained using Energy Dispersive X-ray Spectroscopy (EDX), which allowed conclusions to be drawn. The observed changes were presented in the form of photos showing changes in the composition of the plates, and they were commented on. It should be noted that fire temperatures act destructively, and a number of changes can be observed in the microstructure. The results of the work indicate that, in the future, the use of non-destructive methods will make it possible to assess the degree of degradation of the façade after a fire.

Experimental study of influence of CO2 treatment on fracture toughness of tight sandstone

A large amount of CO2 will be emitted after the burning of fossil fuels, causing global warming and glacier melting which will bring a huge threat to the living environment. Atmospheric clearance through the capture, utilization or storage of CO2 is one of the technologies for dealing with global climate change. In order clarify the mechanization of supercritical CO2 fracturing, the tight sandstone cores in the Jinqiu Gas field, Sichuan Basin were used to carry out the effect research of supercritical CO2 on fracture toughness. The results show that after the treatment of tight sandstone on supercritical CO2, the degradation degree of I-type fracture toughness decreases by 23.6%−33.6% when the soaking days reach 15 days. At the same reaction time, the fracture toughness under 20 MPa and 60 ℃ is lower by 3∼11% than that under 10 MPa and 50 ℃. Meanwhile, the geometric fracture trajectories of sandstone samples before and after the treatment of supercritical CO2 treatment are observed. Before the treatment, the Smax was 1.46 mm and the fracture angle was 10.24°, but after the treatment, the parameters were 0.93 mm and 3.41°, respectively. The fracture trajectories after multiple polishing were observed by SEM imaging, which shows that the fractures can propagate directly through the mineral particles after the supercritical CO2 treatment, which causes the transcrystalline fracture. It is conducive to initiating, propagating, and destroying I-type fractures under smaller external loads. The results further improve the mechanism of CO2 on fracture toughness of tight sandstone, which is useful to explore the feasibility of CO2 fracturing of low-pressure tight sandstone, and provide theoretical support for the safety of CO2 fracturing and CO2 geological sequestration of tight sandstone.

Determination of Sage Tea Polyphenols and Their Antioxidant Effects Using an Electrochemical DNA-Based Biosensor

This study describes two polyphenols, caffeic acid (CA) and (+)-catechin, as well as their antioxidant effects, detected by cyclic voltammetry (CV) using an electrochemical deoxyribonucleic acid (DNA)-based biosensor in sage tea. Square-wave voltammetry (SWV) was applied to investigate CA, as one of the derivatives of phenolic acids, and (+)-catechin, a representative of flavonoids, in sage tea. Square-wave voltammograms (SWVs) of CA showed one peak (0.197 V) and the presence of anodic and cathodic peaks, which suggests an unfolded reversible process on the surface of the glassy carbon electrode (GCE). Furthermore, SWVs of (+)-catechin showed two peaks, which proposes a reversible process at the first peak (0.232 V) and an irreversible process at the second peak (0.6 V) on the surface of the GCE. The determination of the antioxidant effects of sage tea polyphenols was carried out by a DNA-based biosensor. The obtained results indicated that the addition of sage tea to the cleavage solution significantly reduces the degree of DNA degradation. The adopted methods have proved to be simple and applicable tools for the electrochemical characterization of sage tea polyphenols and their antioxidant effects. The study also discusses total phenolic content.

Speech Enhancement: A Review of Different Deep Learning Methods

Speech enhancement methods differ depending on the degree of degradation and noise in the speech signal, so research in the field is still difficult, especially when dealing with residual and background noise, which is highly transient. Numerous deep learning networks have been developed that provide promising results for improving the perceptual quality and intelligibility of noisy speech. Innovation and research in speech enhancement have been opened up by the power of deep learning techniques with implications across a wide range of real time applications. By reviewing the important datasets, feature extraction methods, deep learning models, training algorithms and evaluation metrics for speech enhancement, this paper provides a comprehensive overview. We begin by tracing the evolution of speech enhancement research, from early approaches to recent advances in deep learning architectures. By analyzing and comparing the approaches to solving speech enhancement challenges, we categorize them according to their strengths and weaknesses. Moreover, we discuss the challenges and future directions of deep learning in speech enhancement, including the demand for parameter-efficient models for speech enhancement. The purpose of this paper is to examine the development of the field, compare and contrast different approaches, and highlight future directions as well as challenges for further research.

Speech perception in noise: no interaction between working memory and degree of speech degradation

ABSTRACT Speech recognition in noise (SiN) requires explicit cognitive resources such as working memory capacity (WMC). However, existing evidence on the role of WMC in SiN, especially for young adults with normal hearing, is mixed. This study aimed to systematically evaluate the role of WMC when the degree of speech recognition varied as a consequence of adding background noise of varying intensity levels. Specifically, the objective was to determine whether or not there was an effect of noise level on the recruitment of WMC during speech recognition tasks. Fifty-three young adults (18–37 years) with normal hearing were recruited and their ability to recognize speech in the presence of background noise was measured using sentences and words. Speech-to-noise ratios (SNRs) were varied from +10 to −10 dB SNR in 5 dB steps to manipulate the degree of speech recognition. Listeners’ WMC was also measured using two working memory tasks. A significant positive association between WMC and SiN was found for sentence recognition in noise. However, no significant interaction between WMC and SNR was found for isolated word and sentence recognition tasks. WMC was not found to be a significant predictor of word recognition in noise. These results suggests that for young normal hearing listeners, the recruitment of WMC during sentence recognition, especially in non-informational fluctuating noise, is not modulated by the SNR .

Isolation of Responsive Elements of Planar Multi-Element Photodiodes

In the mass production of multi-element silicon p-i-n photodiodes, the problem of systematic rejection of products due to a decrease in the insulation resistance between the active elements of photodetectors has been revealed. The purpose of this work is to study the causes of insulation resistance degradation and to establish optimal methods for avoiding this phenomenon. A comparative analysis of three insulation methods was carried out: classical insulation by the surface of a non-conductive substrate and a dielectric layer; insulation by means of mesaprofile grooves with a dielectric film; insulation by means of areas of limitation of surface leakage channels isotypic with the substrate material (in this case, p+-type) formed in the gaps between active elements. The study found that the reason for the deterioration of the insulation resistance between the active elements of photodiodes is the presence of conductive inversion channels at the Si-SiO2 interface due to the use of silicon with high resistivity. One mechanism for the formation of inversion channels is the redistribution of impurities in the masking oxide (in particular, phosphorus) and their diffusion to the interface during thermal operations. Another mechanism for the formation of inversion layers is the diffusion of boron from silicon into SiO2 during heat treatment due to the fact that the boron segregation coefficient is less than one. In the manufacture of samples with insulation using non-conductive areas of the substrate, a decrease in insulation resistance was observed as the technological route was performed (after each subsequent operation, the resistance degraded). The degree of degradation can be reduced by reducing the duration of thermal operations. It has been shown that reducing the thickness of the masking oxide causes a decrease in insulation resistance. When using mesa-technology, it is possible to increase the insulation resistance by eliminating the high-temperature oxidation operation and, in fact, due to the absence of a masking coating during phosphorus deposition. Insulation by means of p+-type areas in the gaps between the active elements allows to obtain the highest insulation resistance values. The formation of these regions with a width of 100 μm in the gaps with a width of 200 μm allowed us to obtain an insulation resistance of 25-30 MΩ. To ensure the insulation of the active elements of photodiodes by this method, two thermal operations are added to the technological route. The number of thermal operations can be reduced by doping the entire silicon surface with a low boron concentration before forming a masking coating.

Diffusion in a bicrystal: effect of water uptake through grain boundary on the degradation of halide perovskites

In this work, we investigate the diffusion in a bicrystal strip with a constant concentration of solute atoms/molecules on free surfaces to mimic the diffusion of water molecules in a bicrystal of halide perovskites. The effect of grain boundary diffusion is incorporated in the analysis, and the equation of mass transport in the grain boundary is derived without a time-derivative term. Using the equation of mass transport in the grain boundary, a closed-form solution of the spatiotemporal evolution of the concentration of solute atoms/molecules in the bicrystal is derived. Numerical analysis of the uptake of water in a methylammonium lead iodide (MAPbI3) bicrystal is performed. The degree of degradation of the MAPbI3 bicrystal due to the uptake of water is defined as the ratio of the diffusion length of water in one of the crystal in the bicrystal to the half width of the bicrystal. The numerical results reveal that the degree of degradation of the MAPbI3 bicrystal increases with the increase of the diffusion time and there exists effect of grain size on the degree of degradation of the MAPbI3 bicrystal. The time to reach the same degree of degradation due to the uptake of water is proportional to the width of the MAPbI3 bicrystal of the same thickness, in accord with the experimental results reported in literature. This result points to the need of producing halide perovskite films of large grain sizes in order to improve the structural stability and performance of perovskite-based photovoltaic cells by limiting the structural degradation induced by water diffusion.

Sulfate resistance and degradation mechanism of basalt fiber modified graphite tailings cement-based materials

This paper delves into the modification mechanism and deterioration mechanism of basalt fiber (BF) on the sulfate resistance of graphite tailings (GT) cement-based materials. Initially, the comprehensive properties of basalt fiber modified graphite tailings cement mortar (BFM-GTCM) under different sulfate cycles, such as apparent morphology, water absorption and mechanical characteristics were investigated. Subsequently, the relationship between the evolution of microstructure, interface stability, pore structure, chemical composition and functional groups of BFM-GTCM and its resistance to sulfate erosion under different cycles was revealed by various microscopic characterization and analysis methods (SEM/XRD/MIP/FTIR/DSI). Simultaneously, a corrosion coefficient-pore structure relationship model was also put forth based on multivariate regression theory, and the mechanism enhancing BFM-GTCM resistance to sulfate attack was investigated. The results demonstrated that a suitable blend of BF and GT can prevent sulfate ion penetration, significantly slow down the generation of corrosion products (AFt and gypsum) in cement mortar during sulfate attack, postpone the occurrence of new cracks and the growth of existing ones, improve pore structure, and significantly lessen the degree of durability degradation of BF-GTCM. Among them, 0.3% BF addition and 20% GT replacement was the ideal ratio.

Assessment of reptile response to habitat degradation in arid and semi-arid regions

Reptiles are essential components of global biodiversity and dynamic ecosystems due to their ecological roles and functions. However, they face significant vulnerability to anthropogenic disturbances and habitat degradation, resulting in their classification as the third most threatened vertebrate group globally. The current study examines reptile response to anthropogenic habitat degradation in the highly biodiverse Souss-Massa National Park (SMNP), located on the North African Atlantic coast. During 2021 and 2022, linear transects were established within four habitat categories experiencing varying degrees of vegetation cover degradation (undegraded, slightly degraded, moderately degraded, and highly degraded), caused by livestock overgrazing and vegetation clearance. Based on the comparisons of the Normalized Difference Vegetation Index means, the vegetation cover differed significantly among the selected habitat categories, with a noticeable reduction in the natural vegetation cover as the level of habitat degradation increased. The visual encounter survey technique was used to search a total of 96 transects, with each of the studied habitat categories being represented by 24 transects. Species richness, diversity, abundance, composition and similarities of reptile communities were determined and compared between habitat categories. During the study period, 11 species (438 individuals) were encountered, accounting for 48 % of SMNP reptile fauna. Species richness, diversity and abundance differed significantly among habitat categories, with the lowest means recorded in the highly degraded areas. Reptiles responded differently to habitat degradation based on their taxonomic levels, thus indicating a species-specific impact of degradation. Species composition varied considerably among habitat categories, with highly degraded areas displaying significant differences and the lowest degree of similarity when compared to all other categories (p = 0.0006). Anthropogenic alterations in reptile abundance distribution and species occurrence likely account for the observed differences in species composition within the different habitat categories. The reported reptile responses to habitat degradation might be attributed to factors associated with natural vegetation, such as food availability, microhabitat preferences, or interactions with other species. Exploring these factors in future research could provide further insights into the mechanisms driving reptile community responses to habitat degradation. Such data can provide valuable information for implementing effective conservation measures to prevent anthropogenic habitat degradation and protect threatened species in arid and semi-arid areas.

Development and Initial Characterisation of a Localised Elastin Degradation Ex Vivo Porcine Aortic Aneurysm Model

Aortic aneurysms (AA) occur in 4.8% of people causing 150,000 deaths annually. While endovascular aneurysm repairs reduce surgical morbidity, device-related failures (leak/displacement) are frequent highlighting the need for test models that better represent the mural geometry and compliance changes in human AAs. We aimed to develop and characterise an ex vivo porcine aortic model of AA. The optimal duration of tissue elastase exposure to emulate AA changes in elastin microstructure and content was determined using porcine aortic rings. Elastase-induced changes were quantified morphologically, and mechanical properties assessed via ring tensile testing. Subsequent experiments tested the potential for localised elastase treatment in a 1 cm segment of porcine aorta using a specially designed 3D printed rig. The effect on pressure-diameter behaviour was investigated via inflation-extension testing. Elastase treatment produced time dependent decreases in elastin, resulting in an increased tensile modulus and circumferential length in the ring samples in the final phase of the J-shaped tissue stress-strain curves. In whole aortic segments, localised elastase-induced luminal degradation was successfully limited to a central region. The degree of elastin degradation achieved was sufficient to cause localised dilation with respect to controls under physiological pressures. Localised elastin degradation in porcine aortic segments is feasible and emulates the changes seen clinically in aortic aneurysms.