Variations In Physical Properties Research Articles

Nanoarchitectonics and electrocatalytic properties of platinum nanoparticles in weak polyelectrolytes‐based multilayer thin films

AbstractIn this study, the electrocatalytic behavior of platinum (Pt) nanoparticles (NPs) in a novel multilayered thin film is investigated for proton exchange membrane fuel cells (PEMFC) applications. The multilayer thin films are assembled by the alternate deposition of branched polyethylenimine (BPEI) and poly(acrylic acid) (PAA) from aqueous solutions through a layer‐by‐layer (LbL) technique. Two extreme assembly pH conditions critically influence the films' physical and morphological characteristics, subsequently affecting their electrochemical behavior. Manipulation of the assembly pH modifies the charge density of the weak polyelectrolytes (BPEI and PAA), leading to variations in physical, structural, and electrochemical properties. The LbL thin films assembled at a pH of 9.5 for BPEI and 4.5 for PAA exhibit significantly greater thickness compared to the same film with all components deposited at pH 4.5. This is attributed to in‐and‐out diffusion of the partially charged polyelectrolytes with coiled polymeric conformation (BPEI at pH 9.5 and PAA at pH 4.5). As‐assembled LbL thin films are used as nanoreactors for the deposition of Pt NPs. The nanoscale control over polymeric conformation and charge density significantly influences electrocatalytic performance. 9.5BPEI/4.5PAA thin films exhibit higher electrocatalytic activity relative to 4.5BPEI/4.5PAA systems. This improved performance in 9.5BPEI/4.5PAA multilayers is ascribed to the fact that more carboxylic acid groups of PAA are coated in an exponentially grown behavior, which provides more active sites available for Pt NPs to be deposited. The multilayer thin films containing uniformly dispersed Pt NPs can be an attractive and advanced hybrid electrode material with great promise for the proton exchange membrane fuel cells.

Study of the dynamic behavior of plates in gradient properties with logarithmic and exponential porosity

In this paper, we are interested in the dynamic behavior of porous plates in property gradient, the property gradient material is a new generation of composite material, which is characterized by a gradual and continuous variation of physical properties, in order to attenuate the major singularity of laminar materials, which is the direct transition from one material to another. The proposed theory is based on assumption that the in-plane and transverse displacements consist of bending and shear components, in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments.In order to model our plate as well as possible, we will use a high-order theory with four variables only, by injecting the exact position of the neutral surface. The originality of this work lies in the consideration of two types of porosity distribution “logarithmic and exponential” in the calculation of the position of the neutral surface.The plate is subjected to a vertical load of sinusoidal distribution expressed in double series of Fourier. The equation of motion for FG rectangular plates is obtained through Hamilton’s principle. The closed form solutions are obtained by using Navier technique, and then fundamental frequencies are found by solving the results of eigen value problems.The object of this work is to study the influence of the variation of the volume fraction, the power index and The dimension ratio on the response of  the frequency , and ,the constraints , and and the dimensionless deflection and the dimensionless displacement obtained in the presence of porosity with logarithmic and exponential distribution compared to those uniformly distributed.

Classification and Prediction Method for Dolomite Reservoirs in the Permian Maokou Formation in the Sichuan Basin

The Lower Permian Maokou Formation in the Hechuan area is one of the key horizons for natural gas exploration in the Sichuan Basin, showing a low degree of exploration and great exploration potential. The Lower Permian gas reservoir is mainly controlled by the reservoir, therefore it is subject to the development of the Maokou Formation reservoir. However, due to the strong heterogeneity and significant variations in physical properties of the Maokou Formation dolomite reservoir in the Hechuan area, there are significant differences in seismic response characteristics of reservoirs with different porosities. Through comprehensive analysis of gas testing wells in the Maokou Formation, criteria for reservoir classification were established based on lithology, average porosity, plane porosity, and thickness of dolomite reservoirs. The effective reservoirs in the Maokou Formation were divided into two types: high-porosity reservoirs and medium-porosity reservoirs. On the basis of establishing a physical quantity model for the Lower Permian carbonate rock in the research area, the rock physical characteristics and seismic response characteristics of reservoirs with different pores are determined through model forward modeling, and appropriate methods are selected for prediction. By using the optimization processing method of gathers and wavelet decomposition to remove sidelobes, the issue of seismic abnormal response caused by lateral velocity changes in the underlying Maokou Formation has been solved. The relative strength relationship of seismic response amplitude can effectively characterize the true situation of reservoir development. Then, by using post-stack inversion and pre-stack simultaneous inversion methods, the high-porosity and medium-porosity dolomite reservoirs in the Maokou Formation are classified and predicted, thereby to effectively improve the prediction accuracy of reservoirs, ultimately providing a reliable basis for the exploration and development of the Maokou Formation in the Hechuan area in the later stage.

Gradient Variation and Correlation Analysis of Physical and Mechanical Properties of Moso Bamboo (Phyllostachys edulis).

This study aimed to investigate the gradient properties of bamboo at the microscopic level and provide a basis for improving the utilization rate of bamboo. Using moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) as a research subject, the variation of vascular bundle area percentage, chemical content, relative crystallinity (CR), mechanical properties of different bamboo slivers, and correlation between those parameters were analyzed. From the bamboo green layer (BGL) to the bamboo yellow layer (BYL), the distribution of vascular bundles changed from dense to sparse. Cellulose and lignin mass content decreased gently, and hemicellulose mass content showed gradual increases. The CR showed an order of bamboo middle layer (BML) > BGL > BYL. The tensile modulus of elasticity, tensile strength, bending modulus of elasticity, and bending strength decreased from BGL to BYL. The order of influence degree on mechanical properties of moso bamboo was vascular bundle area, hemicellulose content, lignin mass content, density, and CR, and these factors correlated with mechanical properties at a significant level (p < 0.05). Vascular bundle area had a decisive effect on the mechanical properties of bamboo. The vascular bundle area and density were linearly correlated with mechanical properties, while the lignin mass content and CR were curve-linearly correlated with mechanical properties.

Investigation of thermodynamic state evolution, phase transition and mixing of the hydrocarbon droplet in convective supercritical environments

Liquid alkane droplets transit to supercritical fluids under supercritical conditions. However, the subsequent thermodynamic state evolution, phase transition, and mixing in this case, which directly influences combustion in actual diesel engines, need further investigation. We studied the thermodynamic state evolution, phase transition, and mixing of n-heptane droplets in supercritical laminar nitrogen streams through a set of conservation equations. Non-ideal thermodynamic and transport properties were calculated to incorporate the dramatic variation of physical properties in the supercritical regime. We focus on the effects of Reynolds number, ambient pressure, and droplet size on the thermodynamic state evolution, phase transition and mixing of droplets. Results showed that increasing the Reynolds number can accelerate the evolution of thermodynamic states, which leads to the faster transition of droplets from the liquid phase and supercritical fluids to gas-phase mixtures. With the increased Reynolds number, the phase transition rate is increased and the mixing homogeneity is improved due to the enhanced mass transfer. Caused by the negative correlation between mass transfer and ambient pressure, in higher pressure, droplets after the supercritical transition require more time to transition from supercritical fluids to vapor-phase mixtures. Increasing ambient pressure inhibited the droplet phase transition process and deteriorated the mixing homogeneity, but no significant influence was shown on the droplet dynamic evolution process. Smaller droplets transition faster from liquid phase and supercritical fluids to vapor-phase mixtures. The faster thermodynamic state evolution and faster dynamic evolution process of the smaller droplet leads to its more rapid homogeneous mixing with ambient gasses, but the mode of dynamics is independent of the droplet size.

Estimation of soil organic carbon by combining hyperspectral and radar remote sensing to reduce coupling effects of soil surface moisture and roughness

Soil organic carbon (SOC) is important in the global carbon cycle. Accurate estimation of SOC content in cultivated land is a prerequisite for evaluating the carbon sequestration potential and quality of soils. However, existing SOC prediction studies based on hyperspectral remote sensing neglect the spectral response of the physical properties of surface soil, leading to inadequate model generalization. With the exponential growth of remote sensing data, the development of pixel-level soil spectral correction methods based on multi-source remote sensing data has become an interesting and challenging topic. This method aims to minimize the effect of soil physical properties on spectra, thus addressing the poor spatiotemporal transferability of SOC prediction models due to uncertain variations in surface soil physical properties. In this study, a soil spectral correction strategy is constructed using satellite hyperspectral image (HSI) and synthetic aperture radar (SAR) images through multi-order polynomial regression and convolutional neural networks. This strategy considers soil physical variables such as soil moisture (SM) content and root mean square height (RMSH) of soil surface roughness. The soil spectral correction model and SOC content prediction model were established using 80 soil samples collected from Site 1. Afterward, the performance and transferability of both models were verified using the remaining 25 samples from Site 1 and 50 samples from Site 2. The results showed that: 1) The effect of SM and RMSH on the soil pixel spectrum can be significantly reduced after correcting HSI using soil spectral correction strategy. The correlation coefficients between the corrected pixel spectrum and the ground-based spectrum increase by over 60 % compared with those between the original spectrum and the ground-based spectrum. 2) Soil spectral correction improves the prediction accuracy and mapping capability of HSI for SOC content, with the highest RP2 of 0.743 and RMSEP of 3.455 g/kg at Site 1. 3) Compared with the original HSI-based SOC prediction model, the soil spectral correction strategy based on multi-order polynomial and convolutional neural network reduced the RMSEP of SOC prediction results at Site 2 by 5.082 g/kg and 5.454 g/kg, and the RP2 increased by 0.390 and 0.409, respectively. 4) When predicting SOC content from raw HIS, SM and RMSH contribute to more than 60 % of the bias, with SM having a larger bias than RMSH. The findings of this study emphasize the influence of soil physical properties on SOC prediction and contribute to the existing research on SOC mapping using HSI and SAR data.

Theoretical prediction (DFT) and experimental observation of electronic and electro-optical properties of HATn (n = 5,6,7,8) molecules for optoelectronic applications

The formation of triphenylene core-based discotic mesogens exhibiting a classical columnar phase led to several superior electronic and optoelectronic applications. The present work reports the theoretical investigation of discotic hexaalkoxytriphenylene (HATn; n = 5, 6, 7, 8) mesogens including electro-optical, electronic, and thermodynamic properties using density functional theory (DFT) as a computational quantum mechanical tool. The various physical and chemical properties of these mesogens, such as electronegativity, specific heat capacity, polarizability, absorption, and dipole moment are calculated computationally and discussed in the study. The simulation study reveals the variation in physical properties either follows the odd–even effect or changes monotonically for HATn series. Experiment has been performed for comparison with the theoretical results. The physical and chemical properties of these discotic mesogens change with alkyl chain length variation and explain the structure–property correlation in the molecules. The obtained results of the designed molecular structure held promising applications for optoelectronic devices based on discotic mesogens.

Physical properties variations in a shaly formation across a fault core

Summary Faults in general, and in clay materials in particular, have complex structures that can be linked to both a polyphased tectonic history and to the anisotropic nature of the intact rock. Drilling through faults in shaly materials allows measuring properties such as the structure, mineralogical composition, stress orientation and physical properties. We combine different petrophysical measurements on core samples retrieved from a borehole drilled perpendicularly to a fault zone affecting Toarcian shales from the Tournemire underground research laboratory (France). The borehole is cross-cutting the entire fault thickness which is of the order of ten meters. We perform several types of measurements: density, porosity, saturation directly in the field, and P-wave velocities together with P-waves anisotropy on core samples taken at regular intervals. Special protocols were developed to preserve as much as possible the saturation state of the samples. From our measurements, we were able to track the increase of damage, characterized by a smooth decrease in elastic moduli from the intact zone to the fault core. We then calculated Thomsen's parameters to quantify the elastic anisotropy evolution across the fault. Our results show strong variations of the elastic anisotropy with the distance to the fault core as well as the occurrence of anisotropy reversal.

Temporal variation in soil physical properties of paddy fields in Jeonnam province

Temporal variation in soil physical properties of paddy fields in Jeonnam province

Physicochemical Characterisation of Seeds, Oil and Defatted Cake of Three Hempseed Varieties Cultivated in Spain.

The increasing use of hempseed in food products highlights the need for a comprehensive database for scientific research and industrial applications. In food development, information about the techno-functional properties of raw materials plays a crucial role in determining the suitability of each product for specific applications. Thus, this study aims to characterise three hempseed varieties (Ferimon, Henola and Uso-31), comparing their physicochemical and nutritional compositions. Moreover, the study investigates the impact of hempseed varieties on the techno-functional, physical and thermal properties of the partially defatted hempseed flours (PDHFs) obtained from single screw pressing (SSP) oil extraction. The fatty acid and tocopherol profiles of the dehulled seeds and oil were also analysed. Significant variations in yield and physical properties were observed among hempseed varieties, influenced by genetics, adaptation to agro-climatic conditions and cultivation systems. Despite its lower yield (kg/ha), Uso-31 exhibited superior 1000-seed weight, dehulling yield and larger mean seed size (1.79 ± 0.02 mm). Hempseed oil was rich in unsaturated fatty acids, particularly linoleic (51.2-53.4 g/100 g oil) and α-linolenic (14.88-18.97 g/100 oil) acids, showing variations in γ- and α-tocopherols depending on the variety. The variety also influenced the least gelation concentration (LGC) and techno-functional properties such as water absorption capacity (WAC), emulsifying activity (EA) and emulsion stability (ES). SDS-PAGE and DSC measurements indicated the presence of 11S and 7S globulin proteins with denaturation temperatures above 87.8 °C. These findings confirm that the studied hempseed flours are valuable techno-functional and nutritional ingredients suitable for sustainable food formulations.

New insights into the influence of encapsulation materials on the feasibility of ultrasonic-assisted encapsulation of Mosla chinensis essential oil

The study aimed to estimate the feasibility of α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), and γ-cyclodextrin (γ-CD) to encapsulate Mosla chinensis essential oil (EO) by ultrasonic-assisted method. The physical properties variations, stabilization mechanisms, and formation processes of the inclusion complexes (ICs) were investigated using experimental methods, molecular docking, and molecular dynamics (MD) simulation. Scanning electron microscopy, fourier transform infrared spectroscopy, thermogravimetric analysis, and gas chromatography–mass spectrometry showed that the ICs were successfully prepared, which differentially improved the thermal stability and retained the chemical composition of EO. The dissolution profile showed that the Peppas model can be used to describe the diffuse release mechanism of EO. Finally, molecular docking and MD simulation theoretically confirmed the interaction and conformational changes of carvacrol (the main active component of Mosla chinensis EO) inside the cavity of CDs. The results indicate that hydrogen bonding was the primary driving force for the carvacrol spontaneous access to the cavity. Further, a binding dynamic balance occurs between carvacrol and β-CD, whereas a bind and away dynamic balance occurs in the IC between carvacrol and α-CD, γ-CD. The comprehensive results show that the medium cavity size of β-CD is a suitable host molecule for Mosla chinensis EO of encapsulation, release, and stabilization. A combination of experimental and theoretical calculations is useful for the pinpoint targeted design and optimization of CD molecular encapsulation of small entity molecules. β-CD was rationally screened as a better candidate for stabilizing EO, which provides an option for a meaningful path to realistic EO applications.

Flow measurement in the southern coast of the Caspian Sea

Oceanographic monitoring was conducted in the southern basin of the Caspian Sea to evaluate the physical structure of seawater and sea currents. This monitoring aimed to gather data and analyze the characteristics of the seawater, including temperature, salinity, density, and other relevant parameters. Additionally, the monitoring also focused on studying the patterns and dynamics of sea currents in the region. The collected data and analysis from this monitoring period provided valuable insights into the oceanographic conditions of the southern basin of the Caspian Sea. During storm events, a high level of correlation between the current and wind data was observed in the southern basin of the Caspian Sea during the 2017-2018 monitoring period. The measured current data indicated that the predominant directions were north (N) and northwest (NW). It was observed that strong gusts predominantly originated from the north (N) and northwest (NW) directions. Additionally, a smaller portion of the strong gusts was observed to come from the South-Southeast (S-SE) direction. These findings indicate that the prevailing wind patterns during the monitoring period were primarily from the north and northwest, with a lesser contribution from the South-Southeast direction. The current profiles observed during the monitoring period in the southern basin of the Caspian Sea were primarily influenced by the general circulation pattern of the region. This circulation pattern played a significant role in shaping the current profiles observed during the measurements. In terms of the surface current speed, the maximum recorded value was approximately 200 cm/s, which occurred in January. This indicates that there were instances of relatively high-speed currents in the southern basin of the Caspian Sea during that time. The evaluation of inter-annual variability in vertical structure and seawater temperature profiles during the monitoring period confirmed the presence of seasonal stratification in the water column of the southern basin of the Caspian Sea. This stratification was observed to consist of different layers, including the surface mixed layer, thermocline, and deep-water layers. The formation of these layers is indicative of the seasonal variations in temperature and density within the water column. The vertical changes in the water’s physical parameters during the monitoring period revealed the formation of stratification in the southern basin of the Caspian Sea. In March, it was observed that the water temperature decreased from 11.5°C at the surface to 8.5°C at a depth of 100 m, indicating the presence of a temperature gradient. As the monitoring progressed into May, the stratification became stronger, with the surface water temperature reaching around 23°C. By August, the surface layer of the sea water experienced a significant increase in temperature, reaching 29°C. These observations highlight the development of stratification and the seasonal variations in water temperature during the monitoring period in spring and summer seasons. The water temperature beneath the thermocline layer, specifically at a depth of 100 meters, was recorded to be around 8-8.5 oC. Additionally, the water salinity in the water column exhibited fluctuations between 12-12.5 (psu). Monitoring and understanding physical properties variations are crucial for assessing the oceanographic conditions and their potential impact on marine ecosystems in the southern basin of the Caspian Sea.

Computational insights into the stereo-selectivity of catechins for the inhibition of the cancer therapeutic target EGFR kinase.

The epidermal growth factor receptor (EGFR) plays a crucial role in regulating cellular growth and survival, and its dysregulation is implicated in various cancers, making it a prime target for cancer therapy. Natural compounds known as catechins have garnered attention as promising anticancer agents. These compounds exert their anticancer effects through diverse mechanisms, primarily by inhibiting receptor tyrosine kinases (RTKs), a protein family that includes the notable member EGFR. Catechins, characterized by two chiral centers and stereoisomerism, demonstrate variations in chemical and physical properties due to differences in the spatial orientation of atoms. Although previous studies have explored the membrane fluidity effects and transport across cellular membranes, the stereo-selectivity of catechins concerning EGFR kinase inhibition remains unexplored. In this study, we investigated the stereo-selectivity of catechins in inhibiting EGFR kinase, both in its wild-type and in the prevalent L858R mutant. Computational analyses indicated that all stereoisomers, including the extensively studied catechin (-)-EGCG, effectively bound within the ATP-binding site, potentially inhibiting EGFR kinase activity. Notably, gallated catechins emerged as superior EGFR inhibitors to their non-gallated counterparts, revealing intriguing binding trends. The top four stereoisomers exhibiting high dock scores and binding energies with wild-type EGFR comprise (-)-CG (-)-GCG (+)-CG, and (-)-EGCG. To assess dynamic behavior and stability, molecular dynamics simulations over 100 ns were conducted for the top-ranked catechin (-)-CG and the widely investigated catechin (-)-EGCG with EGFR kinase. This study enhances our understanding of how the stereoisomeric nature of a drug influences inhibitory potential, providing insights that could guide the selection of specific stereoisomers for improved efficacy inexisting drugs.

Features of Anisotropic Drug Delivery Systems.

Natural materials are anisotropic. Delivery systems occurring in nature, such as viruses, blood cells, pollen, and many others, do have anisotropy, while delivery systems made artificially are mostly isotropic. There is apparent complexity in engineering anisotropic particles or capsules with micron and submicron sizes. Nevertheless, some promising examples of how to fabricate particles with anisotropic shapes or having anisotropic chemical and/or physical properties are developed. Anisotropy of particles, once they face biological systems, influences their behavior. Internalization by the cells, flow in the bloodstream, biodistribution over organs and tissues, directed release, and toxicity of particles regardless of the same chemistry are all reported to be factors of anisotropy of delivery systems. Here, the current methods are reviewed to introduce anisotropy to particles or capsules, including loading with various therapeutic cargo, variable physical properties primarily by anisotropic magnetic properties, controlling directional motion, and making Janus particles. The advantages of combining different anisotropy in one entity for delivery and common problems and limitations for fabrication are under discussion.

Crystal symmetry transition and its influence on optical, dielectric, and ferroelectric properties in (1-x)Na0.5Bi0.5TiO3-xSrTiO3 system

Ferroelectric perovskites materials are the most promising materials because of their multifunctional applications as well as the ongoing fundamental research on them. The present study investigates the correlation between the crystal structure and various physical properties such as dielectric, ferroelectric, and optical properties of Sr2+ modified Sodium bismuth titanate Na0.5Bi0.5−xSrxTiO3 (x = 0.00, 0.02, 0.04, and 0.06) synthesized by solid-state reaction method. Rietveld refinement of the X-ray diffraction pattern reveals that the system undergoes a crystal symmetry transition from a two-phase crystal symmetries system (rhombohedral (R3c) and tetragonal (P4bm)) to a three-phase crystal symmetries system (rhombohedral (R3c), tetragonal (P4bm) and Cubic (Pm3̅m)) with the rise in Sr2+ concentration in Na0.5Bi0.5−xSrxTiO3 which is the foremost reason behind the variation of physical properties of the system. The dielectric constant and maximum polarization increase with the Sr2+ concentration up to 2% and it decreases with the further increase in Sr concentration due to the distortion in crystal structure induced by the introduction of cubic phase (Paraelectric) in the system. The maximum value of the dielectric constant is estimated to be 3629 at a low frequency on the Na0.50Bi0.48Sr0.02TiO3 system. The optical band gap (Eg) of Na0.5Bi0.5−xSrxTiO3 (x = 0.00, 0.02, 0.04, and 0.06) ceramics are found to vary between 3.202 eV to 3.172 eV which indicates the semiconducting nature of prepared samples but urbach energy shows an opposite behaviour i.e. increases with Sr concentration.

Study on the morphology, nanostructure and fragmentation properties of diesel and diesel-DMM soot particles oxidized in the air/air-NO environment

As an alternative fuel for diesel engines, dimethoxymethane (DMM) has attracted wide attention in recent years, but its impact on the post-treatment process of diesel exhaust particles has been rarely studied. To get a better understanding of the oxidation kinetics of soot in diesel particulate filters (DPFs), the oxidation process of soot emitted from a modern compression ignition (CI) fueled by diesel (D100) and its blend with 11 vol% dimethoxymethane (DMM11) at the same working conditions were investigated by a thermogravimetric analyzer in the air and air-NO atmospheres in this study, respectively. Soot samples at different oxidation degrees (0 %, 20 %, 50 % and 80 % mass loss) were tested by a high-resolution transmission microscopy to characterize the variations of physical properties (morphology, fractal dimension, primary particle diameter and nanostructure) and oxidation-induced fragmentation properties over the oxidation process. The results showed that DMM11 soot had higher oxidation reactivity than D100 soot, and the oxidation reactivity of soot was enhanced by NO involved in the air atmosphere. During the oxidation process, the fractal dimension of D100 and DMM11 soot aggregates gradually increased, and the number and diameter of the primary particles in an aggregate became smaller. This variation trends became more obvious with the presence of NO in the air environment. The nanostructures of D100 and DMM11 soot particles gradually become ordered (characterized by longer fringe length, narrower separation distance and less tortuosity) as the oxidation proceeds. While, when NO added in the air atmosphere the possibility of microcrystals oxidation inside the particles decrease to slow down the getting-ordered rate of soot. Moreover, the fragmentation probability of D100 and DMM11 soot aggregates decreases gradually as oxidation proceeds. During the oxidation process, the probability of primary particle fragmentation for D100 soot increases continuously, while the probability of DMM11 primary soot particles fragmentation showed an increase-then-decrease trend. Compare with D100 soot, DMM11 soot are more likely to occur the fragmentation behavior over the oxidation process. It is worth noting that the addition of NO to the air atmosphere increases the possibility of aggregate fragmentation, while it decreases the possibility of primary particle fragmentation. This work can provide theoretical basis for the development of high efficiency purification technology for diesel exhaust particles.

Tree canopy area-dependent changes in soil properties: a comparative study in the southern limit of boreal forest distribution

The forest distribution in relation to mountain slope position and the relationships between forest canopy area and soil physical and chemical properties in Mongolia attract the attention of scientists. In this study, we aimed to determine (1) how the slope aspect affects the forest soil physical and chemical properties, (2) how the soil variables correlate with projected canopy area. For comparative study, we established a total of 18 (20 × 25 m2 sized) sample plots in upper forest edge (UFE), upper slope of the forest (USF), lower slope of the forest (LSF), lower forest edge (LFE), sparse forest (SF), and degraded forest area (DFA) stand types with three replications. We measured the tree height, diameter and crown projection area of each growing tree in the sample plots, and collected soil samples for further soil physical and chemical analyses in the laboratory. Our results showed a high variation in growing stock (p < 0.0001), stand density and projected canopy area (p < 0.0001) in relation to mountain slope position and land-use management. We found that the slight changes in stand canopy area projection cause a high variation in soil physical and chemical properties. Among studied stand types higher means of soil temperature and bulk density and lower moisture content were observed on SF and DFA stand types. Contrary, relatively higher content of soil moisture and nutrient elements were recorded in USF, LSF, LFE. We conclude that tree canopy area becomes key determinant factor that positively influences forest soil moisture and fertility by increasing organic matter content in Mongolia.

Numerical investigation of detonation initiation in a modeled rotating detonation engine

In experimental studies, single-wave mode and two counter-rotating wave mode are often observed in rotating detonation combustors. To investigate the mechanism behind different propagation modes, high-resolution numerical simulations of two-dimensional detonation in hydrogen/air mixtures are conducted by solving the reactive Navier–Stokes equations with a detailed chemical mechanism. The numerical results show that the occurrence of the dual-wave detonation propagation mode is positively influenced by an increase in both the channel width and the initial pressure. The dual-wave modes are observed when increasing the channel width, and it is found that the dual-wave modes are caused by increasing the residual premixed gas height near the inner wall. When increasing the initial pressure, the initial peak detonation heat release increases, which leads to the increase in the hot spot intensity formed, and it is found that the dual-wave modes are mainly caused by the interactions between the initial detonation wave and the inner wall. However, the initial equivalent ratio appears to have a relatively minor impact on the detonation propagation mode due to a relatively narrow range variation of physical properties. The peak heat release rate exerts a greater influence on the change of the propagation mode than the induction time does through a wider range test on rotating detonation engines' working condition. Moreover, the velocities and the cell sizes of detonation waves propagating in different directions with different channel widths are also analyzed, revealing that the characteristics of the detonation waves propagating in different directions are nearly the same.

Comparative analysis of physical properties and fatty acid composition of set-yogurt manufactured from different milk types

The increasing consumption of fermented milk products such as yogurt can be attributed to their health benefits as it contains milk-derived essential nutrients and probiotic lactic acid bacteria added as a starter culture. Yogurt is made from different varieties of fresh and reconstituted milk.  The unique characteristics of goat milk provide an opportunity to produce yogurt that meets consumers' preferences. This study determined, evaluated and compared the physical properties, fatty acid composition and the nutrient/health index based on the fatty acids profiles of goat's and cow’s milk set yogurt. The yogurt was made from different milk varieties, which were goat's milk, cow's milk, a combination of goat's and cow's milk, commercial pasteurized full-fat cow's milk, and low-fat cow's milk. Physical properties evaluated were spontaneous or free whey, syneresis, water-holding capacity, viscosity, and texture. The composition of fatty acids was determined, grouped, and used to assess the nutrient/health index. The physical differences between yogurt prepared from goat's milk and cow's milk were established. This study revealed 21 different fatty acids in set yogurt made from goat’s and cow's milk, and the goat’s milk yogurt contained 6 fatty acids in the highest proportion. The yogurt contained an average of 62.3% saturated fatty acids and 37.7% unsaturated fatty acids. This study demonstrated the effect of milk varieties on the variation of yogurt's physical properties and fatty acid composition. This information is valuable to establish the ways to enhance the product's quality.

Soil Microbial Communities in Pseudotsuga sinensis Forests with Different Degrees of Rocky Desertification in the Karst Region, Southwest China

Rocky desertification (RD), a natural and human-induced process of land degradation in karst areas, has become the primary ecological disaster and one of the obstacles to sustainable ecological development in southwest China. Nevertheless, the variation of soil physical and chemical properties, bacterial and fungal communities, and their relationships in RD forests remains limited. Therefore, soil samples were collected from forests under four degrees of RD (NRD, non-RD; LRD, light RD; MRD, moderate RD; and SRD, severe RD) and subjected to high-throughput sequencing of 16S rRNA and ITS1 genes. The results showed a significant reduction in bacterial richness and diversity, while fungal richness and diversity decreased markedly and then showed a balanced trend with the increase in RD degree, indicating that bacteria and fungi did not present the same dynamics in response to the process of RD. The bacterial communities were dominated by Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi, while the fungal communities were dominated by Basidiomycota, Ascomycota, and Mortierellomycota. The PCoA and NMDS demonstrated significant differences in microbial communities in study sites, among which the fungal communities in non-RD forest and LRD forest clustered together, suggesting that fungal communities were more stable than bacteria in RD forest. The db-RDA, Mantel test, and random forest model confirmed the important role of soil BD, pH, SOC, AN, and AP in driving microbial diversity and communities. The IndVal analysis suggested that Chloroflexi, Patescibacteria, Atheliales, and Cantharellales with high indicator values were identified as potential bio-indicators for RD forests. This study could not only improve our understanding of bacterial and fungal community dynamics across RD gradients, but also could provide useful information for the further use of microorganisms as indicators to reflect the environmental changes and ecosystem status during forest RD.