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Impact of an extreme drought event on clonal reproduction and the acclimation capacity of the succulent plant Sempervivum tectorum L.

Functional traits have been defined as those that affect organismal performance, that is growth and development, reproduction and survival, so they have been generally associated with acclimation and adaptation. Here, we aimed to study the impact of an extreme drought event on clonal reproduction and hormonal mechanisms underlying acclimation of houseleek (Sempervivum tectorum L.), a plant adapted to survive harsh environments. We also explored the validity of growth- and stress-related phytohormones as functional traits to evaluate stress acclimation responses in the field. We compared the response of plants, considering both mother rosettes and newly produced clones, to a very extreme summer drought event occurring in small cliffs in Les Guilleries mountains (NE Spain). We measured various stress makers in the field together with hormonal profiling through a metabolomic approach using liquid chromatography coupled to tandem mass spectrometry. Results showed that clonal propagation was arrested during the study period and revealed a 100-fold increase in abscisic acid content from spring to summer both in mothers and new clones, concomitantly with reductions in relative water content, which decreased by 20% only. The stress-related bioactive jasmonate, jasmonoyl-isoleucine increased simultaneously with abscisic acid, while growth-related hormones, including bioactive cytokinins (2-isopentenyl adenine and trans-zeatin) decreased from spring to summer, which was consistent with growth arrest. It is concluded that S. tectorum adjusts recruitment of new clones during periods of low water availability and withstands extreme drought events during the summer (preventing severe cell turgor loss at soil water contents below 2% and temperatures above 43 ºC) by successfully activating a complex hormonal response that underlies the great capacity of this species to survive extreme climatic events.

Enhancement of ketocarotenoid production using the heterologous orange protein from Ipomoea batatas in indigenous microalga Ettlia sp.

Astaxanthin, one of the most powerful natural antioxidants, is used in high-value industries such as those of cosmetics, nutraceuticals, and food products derived from microalgae. In this study, Ettlia sp. mutants were generated by expressing two types of heterologous orange proteins, IbOr and IbOr-R96H, in which the 96th arginine of IbOr was substituted with histidine derived from Ipomoea batatas to enhance astaxanthin production. The Ett-IbOr-R96H mutant showed a 2.4-fold increase in β-carotene content compared to the wildtype (4.59 mg g−1DCW), reaching 10.82 mg g−1 under high-light conditions via two-phase cultivation. Under the stress treatment combination of high-light intensity and nitrogen deprivation, total carotenoid content increased to 17.24 mg L−1 and 21.94 mg L−1 in Ett-IbOr and Ett-IbOr-R96H, respectively. The astaxanthin and canthaxanthin contents in Ett-IbOr-R96H was 4.89 mg L−1 and 0.47 mg L−1, respectively, which were 1.8- and 1.5-fold higher, respectively, than those in Ett-IbOr. Additionally, photosynthetic efficiency (Fv/Fm) recovered in Ett-IbOr-R96H under dual-stress conditions compared to the wildtype while reactive oxygen species levels decreased throughout the cultivation period. Our findings suggest that the heterologous IbOr expression in Ettlia sp. may be an effective approach for enhancing the production of ketocarotenoids and improving stress resistance for industrial applications.

Effect of different drying techniques on the physicochemical and nutritional properties of Moringa oleifera leaves powder and their application in bakery product

The study analyzed the influence of drying methods and conditions on the quality of moringa leaves powder (MLP) and determined the optimal MLP to wheat flour ratio for cake development. Cabinet drying temperatures enhanced mass and tapped density but reduced the angle of repose, water retention capacity, and oil retention capacity. The moisture content of cabinet-dried MLP samples exhibited a substantial reduction as temperature is increased. The crude protein and fat content increased with increasing drying temperatures. Vacuum dried samples had the highest fiber content (16.62g/100g). Cabinet dried samples at 60°C had the highest ash content (8.37g/100g). The energy obtained from MLP dried in a cabinet at 70°C was the highest (383.33 Kcal/kg). The mineral composition of MLP in vacuum drying showed the largest growth. Sun drying was less efficient in preserving antioxidant components, while vacuum drying was the most successful. But sun drying was more cost effective than that of other drying methods. The composition of cakes formulated from MLP and wheat flour blends exhibited notable variations characterized by an increase in protein content and decrease in carbohydrate content with the incorporation of MLP. 5% and 10% MLP enriched cakes showed the best customer acceptance.

Effect of iron-based nanomaterials on organic carbon dynamics and greenhouse gas emissions during composting process

Iron-based nanomaterials as effective additives can enhance the quality and safety of compost. However, their influence on organic carbon fractions changes and greenhouse gas emissions during composting remains unclear. This study demonstrated that iron-based nanomaterials facilitate the conversion of light organic carbon fraction into heavy organic carbon fraction, with the iron-based nanomaterials group showing a significantly higher heavy organic carbon fraction content (41.88%) compared to the control group (35.71%). This shift led to an increase in humic substance content (77.5 g/kg) and a reduction in greenhouse gas emissions, with CO2, CH4, and N2O emissions decreasing by 20.5%, 39.7%, and 55.4%, respectively. Additionally, CO2-equivalent emissions were reduced by 42.9%. Microbial analysis revealed that iron-based nanomaterials increased the abundance of Bacillus and reduced the abundance of methane-producing archaea such as Methanothermobacter and Methanomassiliicoccus. These results indicated that the role of iron-based nanomaterials in regulating reactive oxygen species production and specific microbial communities involved in humification process. This study provides a practical strategy for improving waste utilization efficiency and mitigating climate change.

Astragaloside for Improving Diabetic Vasculopathy Based on Microalbuminuria and C-Reactive Protein

Astragaloside has an ameliorative effect on diabetic vasculopathy. In this experiment, we investigated the role of astragaloside in improving diabetic vasculopathy. Eighty cases of type 2 diabetes mellitus (T2DM) patients with microalbuminuria (MAU) symptoms were selected and divided into T2DM group, astragaloside group, astragaloside+SRI-011381 group and astragaloside+ LDN193189 group. Another 20 healthy check-ups were selected as control group. We detected the content of C-reactive protein (CRP), ankle-brachial index (ABI) for both lower limbs, ultrasound examination of both lower limbs, and determined the vascular internal diameter (D), peak flow rate (Vmax), blood flow (Vol) of these three arteries, as well as grading the degree of lesion and scoring. T2DM group showed an increase in CRP level and UAlb content, decreased vessel internal diameter, an increased peak flow rate, decreased blood flow and ABI index, and a higher incidence of arteriopathy, which were all reversed in the Astragaloside group. The incidence of arterial lesions was lower. Compared with astragaloside group, serum CRP level and urine albumin content were increased in the astragaloside+SRI-011381 group, and serum CRP level and urine albumin content were decreased in the astragaloside+LDN193189 group. Moreover, inhibition of TGF-β/Smad pathway improved diabetic vasculopathy. Astragaloside therefore improves diabetic vasculopathy and slows diseased progression by inhibiting TGF-β/Smad signaling, lowering CRP levels as well as urinary albumin levels, hindering vasoconstriction and increasing blood flow.

Computational Intelligence for Modeling the Rheological Properties of the Developed Hydrated Lime-Based Alkali-Activated Materials

The development of alkali-activated materials (AAMs) has gained attention as a sustainable alternative to Portland cement-based concrete. A key factor in AAM performance is its rheological behavior, which influences workability and pumpability. Accurate prediction of these properties is vital for optimizing mix design. This study introduces a computational framework using ensemble and non-ensemble machine learning (ML) techniques to model the yield stress (YS) and plastic viscosity (PV) of AAMs. A comprehensive dataset from previous experiments was used to train models, including artificial neural networks (ANN), gene expression programming (GEP), decision tree, random forest, adaptive boosting, and gradient boosting. The models achieved R² values exceeding 0.95 and correlation coefficients above 0.97. Error metrics, such as MAPE, MAE, MSE, and RMSE, further validated the models’ generalizability. A parametric analysis showed that a 20% increase in hydrated lime (HL) content raised YS by 350Pa, which is similar to the effect of varying fly ash (FA) from 60% to 100%. A 40% increase in FA and HL content increased PV by 4Pa.s and 25Pa.s, respectively. A 3% rise in sodium silicate led to a 400Pa increase in YS, while a similar increase in sodium hydroxide raised YS by 170Pa and PV by 15Pa·s. Overall, this study provides an effective tool for optimizing AAM mix designs by accurately predicting rheological properties and quantifying the impact of key parameters, contributing to the advancement of sustainable cementitious materials in construction.

Preparation of high-value carbon nanotubes from real waste plastic towards the negative carbon technology

The preparation of carbon nanotubes (CNTs) from plastics is of great significance for realizing high value utilization of waste and reducing carbon emission. Here, several kinds of real waste plastics were introduced into catalytic pyrolysis, and the process was also optimized. The results showed that the presence of impurities (e.g., adhesive labels) reduced the initial activation energy of the pyrolysis reaction, and the pyrolysis process was extended and could be divided into two stages. During the catalytic process, impurities play a toxic role on the catalyst at higher temperatures and result in the agglomeration of catalyst particles and a decrease in catalytic activity. Less than 10 wt.% carbon fibers were collected from milk cup waste. However, after experimental optimization, the influence of the impurity component was greatly reduced. The toxic effect of organic impurity volatiles on a catalyst was avoided by employing a segmented catalytic pyrolysis process, which led to an increase in solid carbon content of more than 20 % for express package waste. Simultaneously, more uniform and smoother CNTs can be found in the obtained solid carbon. The process of preparing carbon nanotubes with higher yield and better quality is feasible and has important application prospects in the utilization of waste plastics.

Structural and functional optimization of egg white protein hydrogels by succinylation: Gel properties and mineral enrichment

The development of novel gel-mineral supplements is important for improving the health of patients with dysphagia. In this study, we used natural egg white protein (NEWP) and phosphorylated egg white protein (STEWP) as controls. We modified NEWP with succinic anhydride to produce varying degrees of succinylated egg white protein (SAEWP). The addition of 20 % (w/v) succinic anhydride increased the β-sheet content of SAEWP from 11.97 % to 50.60 %, which stabilized the gel structure and formed a uniformly ordered three-dimensional network, resulting in the average pore size of SAEWP could reach >80 μm. Compared to NEWP, SAEWP hydrogel with 20 % succinic anhydride showed a 22.27 % increase in water holding capacity, a 56.13 % increase in hardness, and a 173.01 % increase in elasticity. Immersion in a calcium chloride solution resulted in a 220 % increase in calcium content. This study provides new insights into the development of innovative gel mineral supplements.

Influence of atomic substitution on the structural stability and half-metallicity of Fe2-xCrxCoSi (x = 0 to 1) alloys

Bulk Fe2-xCrxCoSi (x = 0, 0.25, 0.5, 0.75, and 1) Heusler alloys have been prepared by arc melting method. Alloys with 0.0 ≤ x ≤ 0.75 show a highly ordered phase pure XA structure. However, 17 % of an impurity (A15 phase) was detected in the alloy with x = 1. The saturation magnetization (Ms) and Curie temperature (TC) decreased linearly with an increase in Cr content for alloys with x ≤ 0.75. Ms measured at 5 K followed the Slater–Pauling rule for half-metals. Ab initio calculations with the GGA + U approach revealed that spin polarization (P) increased with an increase in Cr and eventually reached 100 % for the alloys with x = 0.5. Though Fe-Co disorder affects P, it is still high (>98 %) for alloys with x ≥ 0.5. Despite the smaller bandgap (0.61 eV) of Fe1.5Cr0.5CoSi than FeCrCoSi (0.91 eV), it has higher Ms, elevated TC, and 100 % P. These factors, coupled with the challenges associated with obtaining phase pure FeCrCoSi alloy, make Fe1.5Cr0.5CoSi a preferred candidate for spintronic device applications.

Shear band analysis of silt-clay transition soils under three-dimensional stress-strain conditions

This paper investigates shear banding as a possible failure mode for silt–clay transition soils under general three-dimensional stress conditions. Drained and undrained true triaxial tests with constant b values were performed on tall prismatic specimens of such soils with systematically varying silt contents. Based on the values of critical plastic hardening modulus, shear banding does not govern the strength characteristics of the soils for b values less than 0.2. For larger b values, shear band formation is essentially critical as it takes place in the hardening regime of the stress–strain curves prior to the smooth peak failure points. An increase in silt content appears to move the onset of shear banding to lower levels of shear in the stress–strain relations of the silt–clay transition soils. It is also demonstrated that a non-associated constitutive model with a single hardening law is capable of accurately predicting the onset of shear banding in normally consolidated silt–clay transition soils based on bifurcation theory.

Experimental study on metallic impurity behavior with boronization wall conditioning in EAST tokamak

Operation of EAST tokamak with full metal wall without any wall conditioning are attempted in 2023 and 2024 experimental campaign to address the issues related to ITER tungsten wall operation. It is found that H-mode plasma could be sustained even with a substantial increase in metallic impurity content caused by strong plasma-wall interaction under uncoated metal wall. Boronization wall conditioning is therefore performed to improve the plasma performance with higher injected power. This study aims to quantitatively assess the impact of boronization wall conditioning on metallic impurity concentration and behavior in the EAST tokamak. It is then proved to be an effective wall conditioning approach for significantly controlling high-Z impurity content. In this work, the impurity spectra at extreme ultraviolet (EUV) wavelength range measured by sets of fast-time-response and space-resolved EUV spectrometers are widely used in the data analysis. The variation in the boron content in plasma after boronization are investigated by monitoring the 2nd order of B V line at 48.59 Å. It is found that the persistence time of boron in EAST device after a boronization with 10 g of carborane (C2B10H12) is about 2000 s (∼150 shots) of discharge duration. The impact of different wall conditions (uncoated metal wall and boron coated wall) on metallic impurity content are then quantitatively studied. After boronization, the concentration of tungsten (CW) and molybdenum (CMo) dropped by 85 %, e. g., from 2.0 × 10-4 to 4.1 × 10-5 and from 4.6 × 10-5 to 6.3 × 10-6, respectively. While the concentration of copper (CCu) and iron (CFe) decreased by approximately 50 % and 65 %, respectively, e. g., from 4.3 × 10-5 to 2.1 × 10-5 and from 2.0 × 10-4 to 6.9 × 10-5. A comparison of the line emission profiles from tungsten ions of W26+ − W32+ and W43+ before and after boronization reveals an overall reduction in the intensity while without obvious change in the profile shape, which suggests a reduction in metallic impurities source after boronization instead of altering impurity transport in core plasma significantly.

Exploring the kinetics and thermodynamics of TiFe0.8CrxMn0.2-x hydrogen storage alloys

The influence of Fe substitution by Cr and/or Mn on the hydrogenation properties of TiFe0.8CrxMn0.2-x hydrogen storage alloys was explored for several substitution amounts (x = 0, 0.05, 0.1, 0.15 and 0.2). The synthesized alloys consisted of a dominant TiFe (cubic, CsCl-type) and a secondary C14 Laves phase (hexagonal, MgZn2-type). The increase in Cr content, and consequently in C14 Laves phase fraction, improved the first hydrogenation kinetics and the hydrogen intake after activation (1.60–1.70 wt% H2 at 30 °C within 3 min), while substantially stabilizing the monohydride phase. The reaction enthalpy obtained from pressure-composition-temperature (PCT) curves hence increased along Cr substitution, ranging 24.35 ± 0.34 to 35.39 ± 1.00 kJmol-1 for the absorption, and 31.08 ± 1.39 to36.34 ± 1.99 kJmol−1for the desorption (absolute values). These experimental findings were in good agreement with density functional theory (DFT) predictions performed across the explored composition space. The estimated entropy values on the other hand remained nearly constant, fluctuating between 84.28 ± 4.76 and 102.64 ± 3.12 J mol−1 H2 K−1 for the absorption, and 100.46 ± 9.71 up to 105.45 ± 4.31 J mol−1 H2 K−1 for the desorption. Solid-gas reaction modeling showed that, under practical service conditions, the hydrogenation of activated alloys was interface-controlled followed by diffusion-controlled mechanisms as the reaction proceeded.

Whole-pathway stimulation of anthocyanin biosynthesis by UDP-glycose: flavonoid glycosyltransferase gene (UFGT) providing new insights into natural product development based on plant cell factory

Anthocyanins are a type of plant natural products (PNPs) that play a crucial role in various fields, including food, medicine, cosmetics, and dyes. However, their primary source is plant extraction, leading to significant ecological damage and resource wastage issues. To address the challenge of achieving ecologically sustainable high-throughput anthocyanin production, this study proposes a plant cell factory (PCF) strategy based on suspension cell culture (SCC). In this study, the key gene VdUFGT involved in anthocyanin biosynthesis was cloned from Vitis davidii, and gene overexpression was conducted using Agrobacterium-mediated methods. Notably, the vgt3 transgenic cell line exhibited 4.4-fold increase in anthocyanin content, reaching 286.9 μg/g (FW) in solid medium, along with enhanced levels of flavonoids and proanthocyanidins. Integrative analysis of transcriptomics and metabolomics demonstrated that VdUFGT significantly promoted the expression of genes involved in anthocyanin biosynthesis, leading to the enhanced accumulation of various flavonoids, including anthocyanins. A small-scale plant cell factory was established, achieving an impressive production of 4.11 mg/g (DW) of anthocyanin within just 12 days, which is 8.5 times higher than that of the WT cell line, with the yield of purified freeze-dried anthocyanin powder reaching 3.17%. The plant cell factory, employing genetic engineering and suspension cell culture, offers a safe, ecological, economical, and efficient approach for the high-throughput production of plant natural products such as anthocyanins.

Effects of interaction between wheat bran dietary fiber and gluten protein on gluten protein aggregation behavior.

Effects of wheat bran dietary fiber (WBDF) as a nutritional additive on flour products quality mainly depends on the interaction between WBDF and gluten protein. In this study, the effects and mechanisms of WBDF with different particle sizes and additive amounts on gluten protein aggregation behavior were investigated. The results showed that the addition of WBDF led to a decrease in free sulfhydryl content, particle size, molecular weight and gluten macromer (GMP) content, an increase in zeta potential and SDS-extractable protein content, and a deterioration in the gluten network morphology compared to the control group, suggesting that the aggregation behavior of gluten protein was inhibited. When WBDF was added at 3 % and 6 %, dilution effect, mechanical shear, steric hindrance, and non-covalent binding were the main mechanisms leading to depolymerization. Further addition of WBDF (9 %, 12 %) inhibited the depolymerization of gluten protein due to competitive hydration and non-covalent binding. However, when WBDF was added at 15 %, the dilution effect, mechanical shear and steric hindrance of WBDF (88 μm < particle size<150 μm) dominated, and their inhibitory of aggregation induced the formation of a loose gluten network structure. In contrast, the weaker mechanical shear and steric hindrance effects of WBDF (particle size<88 μm) mitigated the degradation of gluten network structures by WBDF.

Crystal structure and magnetic properties of Fe doped BaTiO3 at morphotropic phase boundary

Ceramic compounds BaTi1-xFexO with x = 0 – 0.2 prepared by solid state reaction technique were studied using X-ray diffraction, Raman spectroscopy, and magnetometry methods focusing on the correlation between the structure and magnetic properties. Chemical doping with Fe ions leads to a concentration driven structural transformation from the single phase tetragonal (T-) structure to the hexagonal (H-) structure with a mixed structural state stable in the concentration range 0.06 <x ≤ 0.2. Increase in the Fe ions content causes a stabilization of weak ferromagnetic state driven by the exchange interactions Fe3+ – O – Fe3+ ions strongly dependent on the structural positions of the Fe ions. Increase of the dopant content above x = 0.08 leads to a decrease of the remnant magnetization which is mainly caused by a stabilization of Fe4+ ions as well as by the lattice defects associated with oxygen vacancies formed to keep electroneutrality of the compounds. The results of the structural and magnetization measurements allowed to itemize the type of exchange interactions between Fe ions residing different structural positions of the hexagonal lattice as well as to reveal structural instability of the T- and H- phases under ambient conditions and applied electric field which shows a possibility to control the structure and magnetic properties of the mixed compounds via external stimuli.

Exogenous melatonin improves peanut field productivity and quality at reduced nitrogen application

ContextNitrogen (N) plays integral roles in plant growth and yield. Finding ways to increase plant yield with reduced N usage will promote both agricultural and environmental sustainability. Melatonin acts as a multifunctional regulatory molecule in numerous metabolic processes crucial for plant growth and development as well as response to environmental stresses. The effects of melatonin on the material accumulation and transport, source-sink dynamics, as well as its association with yield and quality formation of peanut (Arachis hypogaea L.) remain unclear, especially at different N levels. ObjectivesWe aim to investigate the response mechanism of melatonin in peanut plants subjected to reduced N application, in order to confirm the hypothesis that melatonin regulates carbon and N accumulation and transport, and coordinates source-sink relationships to increase production and improve quality. MethodsThis study examined the effects of two seed dressing treatments (with or without 0.5μM MT) and three N fertilizer levels (90, 135, and 180kg/ha) using a randomized complete block design with split plots and three biological replications over 2021 and 2022. The evaluation focused on photosynthetic physiology, enzyme activities related to carbon and N metabolism, accumulation and transport of dry matter and N, yield, and quality, while exploring the relationships among these variables. ResultsMelatonin-treated plants had more stable carbon and N metabolism than the untreated ones. This stability was linked to improved photosynthesis, sucrose production, and N assimilation, especially at the reduced N levels (90 and 135kg/ha). Across three N levels and two years of field tests, MT increased peanut dry matter by 23.49% from 455.63g/m2 to 562.66g/m2, enhanced the accumulation and mobilization of dry matter and N to grains by increasing peanut grain mass by 22.41-29.07% at different N levels. This process appears to subsequently elevate the effective pod rate, leading to an average increase in pod yield, fat and protein content by 12.63%, 7.95%, and 10.33%, respectively, over a two-year period and across three N application levels. ConclusionsPlants subjected to melatonin treatment exhibited a coordinated source-sink relationship, which is manifested in high photosynthetic capacity and a high proportion of assimilates transported to pods, thus promoting effective proportions and pod fullness to improve peanut yield and quality under reduced N application. SignificanceOur research provided insights into the response mechanism of melatonin on peanut carbon and N metabolism across various N treatments, contributing to a deeper understanding of how melatonin enhances crop yield and quality.

Evolution of strengthening precipitates in Al-4.0Zn-1.8Mg-1.2Cu (at.%) alloy with high Zn/Mg ratio during artificial aging

Evolution of strengthening precipitates, including their types, sizes, volume fraction, and chemical compositions in Al-4.0Zn-1.8Mg-1.2Cu (at.%) alloy during artificial aging, were investigated using anomalous small-angle X-ray scattering (ASAXS), three-dimensional atom probe techniques (APT), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and density functional theory (DFT) calculation. Upon aging, Cu-containing clusters merge with adjacent clusters to form larger clusters, which then act as nucleation sites for GPη' zones. As aging proceeds, GPη' zones grow up to η'I metastable phase with seven atomic layers on {111}Al planes, and this process is controlled by diffusion of Mg atoms. Cu atoms have a low diffusion rate and do not participate into the growth of precipitates within the first 60mins of aging. As aging time increases, Cu atoms enter the η'I metastable phase, leading to a significant increase in Cu content and (Zn+Cu)/Mg ratio; η'I metastable phase grow, and after exceeding about 7nm, gradually transform into the η'II metastable phase with ten atomic layers by adding three new atomic layers at one side. GPη' zones, η'I metastable phase and η'II metastable phase have symmetric interface structures. The precipitation sequence during aging to peak state can be summarized as: atomic clusters → GPη' zones → η'I metastable phase → η'II metastable phase.

Micro-mechanical performance study of the interfacial transition zone in ultra-high performance concrete containing coarse aggregates based on digital image correlation method

To measure the mechanical properties of the interfacial transition zone (ITZ) in ultra-high performance concrete with coarse aggregates (UHPC-CA) under direct load, a mesoscopic experimental analysis is performed using a combination of an electron microscope (EM) camera and digital image correlation (DIC) technology in this study. With such a methodology, the stress-strain curve of the ITZ under compression is measured directly. Furthermore, the distribution of the nominal compressive elastic modulus (E⁎) and Poisson's ratio (v) of the ITZ is obtained. Finally, the effects of granulated blast-furnace slag (GGBS) contents (0%, 30%, 40%, and 50%) on ITZ’s properties are investigated, and their relevance to microstructure is further explored by scanning electron microscope (SEM). The results indicate that the E⁎ in the ITZ follows a 'U'-shaped distribution. In comparison to the reinforced matrix, a compaction process in ITZ is observed obviously, resulting in a smaller v in this region. Besides, as the GGBS content increases, the mesoscopic mechanical properties of the ITZ gradually decline.

A numerical study of the effect of interfacial thermal resistance on thermal conductivity of Cu-B/diamond composites

Cu/diamond composite is a promising thermal management material for heat dissipation of high-power electronic devices. Heat transfer models for a Cu-B/diamond composite with varying boron contents added in the Cu matrix were constructed using the finite element (FE) method, based on the results from transmission electron microscopy (TEM) characterization. The heat transfer behavior of the Cu/diamond composites was then investigated. The predicted effective thermal conductivities were compared to experimental values, using both analytical model calculation and FE simulation. The FE simulation effectively illustrates the dependence of thermal conductivity on interface structure evolution of the composite. The heat transfer behavior of the Cu-B/diamond composites varies as the boron content increases. In the Cu-0.3wt%B/diamond composite, most of the heat flow is concentrated and transferred along the diamond particles. In the Cu-1.0wt%B/diamond composite, the heat flux distribution and flow direction are similar to those in the Cu-0.3wt%B/diamond composite, but the heat flux is substantially lower. The heat transfer behavior is closely related to the interactions between the two phases in the composite and is intensively influenced by the evolution of interfacial carbide morphology. The FE simulation provides a more accurate prediction of effective thermal conductivity compared to the analytical model calculation, as it considers the reasonable interactions between the two phases relating to the actual interfacial structure. The findings provide a fundamental basis for optimizing the interfacial structure of Cu/diamond composites and further improving their thermal conductivity.

Effect of particle gradation and rock block content on soil-rock mixture shear strength parameters

Soil-rock mixture (SRM) is highly inhomogeneous and loose geomaterial found in the quaternary formation, composed of a certain percentage of rock blocks, fine-grained soil, and pores. In Peninsular Malaysia, SRM can commonly be found in the granitic formation covering the mountainous areas where slope failures are prone to occur due to deep tropical weathering, heavy rainfall, and steep terrain. Numerous research studies have been conducted to investigate the mechanical behaviour of SRM, especially the influence of rock block content. However, the effect of particle size distribution has been studied in limited detail. This study uses sieve analysis, specific gravity, compaction, and direct shear box tests to determine the shear strength parameters of weathered type SRM with particle size distribution. The sample collected was divided into well-graded, poorly-graded, and gap-graded types of particle size distribution with 30%, 50%, and 70% rock block content, respectively. The percentage of rock block content is crucial in controlling the shear strength parameters. The specific gravity, dry density, optimum moisture content, and estimated porosity values measured show a considerable difference when the particle size distribution (PSD) and rock block content change. The findings also show that for a well-graded SRM, cohesion and friction angle values show a non-linear relationship against the rock block content. Meanwhile, as the rock block content increases, the cohesion decreases and inversely has an increment of friction angle for poorly-graded SRM. In contrast, the cohesion of gap-graded SRM increases when the rock block content increases. Hence, by understanding the influence of particle size distribution on the shear strength parameters of SRM, a better evaluation can be made in designing slope hazard mitigation.