High Degree Of Dispersion Research Articles

Dodecylamine‐assisted hydrothermal synthesis of carbon‐supported ultrafine IrRu Nanoparticles for oxygen evolution electrocatalysis and overall water splitting

Ruthenium (Ru)‐ and iridium (Ir)‐based nanomaterials have always been regarded as efficient electrocatalysts for oxygen evolution reaction (OER) in acidic electrolytes. Herein, we develop a facile dodecylamine‐assisted hydrothermal synthesis for producing carbon‐supported IrRu alloy nanoparticles with controllable Ir/Ru ratios and ultrafine sizes towards high‐efficiency OER and overall water electrolysis. In this strategy, the dodecylamine that serves as a capping and reducing agent enables the final IrRu alloy nanoparticles to possess average sizes < 3 nm and high degree of dispersion on carbon substrate. By combining high OER activity of Ru with high acidic robustness of Ir, the as‐prepared IrRu/C nanoparticles at a suitable Ir/Ru ratio of 1/3 show good activity and durability for the OER electrocatalysis and overall water splitting. In specific, the Ir1Ru3/C catalyst exhibits the lowest overpotential of 302 mV at the current density of 10 mA cm‐2 and the highest mass activity of 120.5 mA mg‐1 at 1.532 V for OER in 0.5 M H2SO4 electrolyte. In addition, a two‐electrode acidic electrolyzer assembled with Ir1Ru3/C at anode and commercial Pt/C at cathode (Pt/C|| Ir1Ru3/C) exhibits a low cell voltage of 1.44 V for achieving the current density of 10 mA cm‐2, along with a satisfied 20‐h durability.

Impressive reinforcement on the anti-corrosion ability of the commercial fluorocarbon paint via an amino groups modified graphene

The interaction with the matrix and the dispersion within the matrix hinder the realization of graphene's potential as an anti-corrosive filler. Herein, a -NH2 modified graphene-based filler (PS-PVP@NH2-rGO) was designed to simultaneously address these issues in the fluorocarbon resin (FEVE) coating. Reinforing FEVE coating with PS-PVP@NH2-rGO, the wear rate and the lowest-frequency impedance modulus after a 7-day immersion were found to be 0.35 times and 177.3 times those of FEVE coating respectively. Ultraviolet-Visible spectra confirmed the excellent dispersibility of PS-PVP@NH2-rGO. The designed differential scanning calorimeter experiment demonstrated the close interaction between PS-PVP@NH2-rGO and the FEVE matrix. Due to this close interaction, PS-PVP@NH2-rGO exhibited a high degree of dispersion within the FEVE matrix rather than self-aggregation, then concentrated the stress outside, absorbed energy produced during the friction process, and enhanced the coating's wear resistance. A complicated “labyrinth” was also created by the fillers. With chemical interactions, the fillers and the surrounding FEVE matrix formed an integrated whole, making the “obstacles” created by the fillers more significant. Consequently, the strong barrier effect resulted in superior anti-corrosion performances of PS-PVP@NH2-rGO/FEVE coating. Introducing -NH2 groups in was proven to effectively complete the coating, improve coating's quality and barrier effect, and finally prevent corrosive media. This study aims to provide design ideas and theoretical supports for high-performance heavy-duty anti-corrosive coatings.

Synthesis, characterisation and functionalization of Hercynite nanoparticles for improved antibacterial activity

Hercynite i.e.,FeAl2O4 is an earth-abundant spinel mineral with a cubic crystal structure and belongs to the normal spinel ferrites possessing optical absorption in the visible range as well as superior magnetic and thermal properties. Herein, we synthesized nanosized FeAl2O4 where the citric acid-mediated sol–gel auto-combustion method was employed to achieve its pure phase and studied its physicochemical properties. Furthermore, the superior colloidal dispersion stability of the FeAl2O4 nanoparticles was achieved required for antibacterial activity and standardised via post-synthesis surface functionalisation using amino-propyl-triethoxysilane (APTES). We further characterised the material using states of art characterisation techniques for their structural, morphological, optical and thermal properties. Finally, the antibacterial activity of pure and surface functionalised FeAl2O4 nanoparticles was investigated against the Escherichia coli (E. coli) strain. We observed good penetration of surface functionalised FeAl2O4 nanoparticles into the bacterial membranes due to the high degree of dispersion achieved via cationic surface charge. Conclusively, a key finding of this study is the enhanced antibacterial properties of surface functionalised FeAl2O4 nanoparticles for the concentration of 31 µg/mL compared to pure FeAl2O4 nanoparticles at 62 µg/mL. This study has great relevance in the area of wound healing and tissue regeneration in the future.

A novel water‐based mechanochemical approach for surface modification of graphene platelets and their epoxy nanocomposites

AbstractGraphene (nano) platelets (GPs) are cost‐effective and possess high structural integrity, but their limited surface functional groups hinder their compatibility with polymers. In this study, an eco‐friendly, water‐based mechanochemical approach was developed to modify GPs with polyacrylamide (PAM), creating PAM graphene platelets (PAM‐GPs) with a grafting ratio of approximately 15%. The platelet was measured to be a few nanometers in thickness, and the grafted PAM provides abundant functional groups, including amide groups, which enhance compatibility with polymers. A typical polymer, bisphenol‐A epoxy, was compounded with PAM‐GPs, resulting in a high degree of exfoliation and dispersion of PAM‐GPs within the matrix. The resulting epoxy/PAM‐GP composites exhibited significantly improved mechanical properties, including an 18% increase in Young's modulus and a substantial enhancement in fracture toughness, with a 71% increase at a low filler fraction of 0.5 wt%. These improvements are attributed to the effective interfacial interaction between the PAM‐GPs and the epoxy matrix, facilitated by the grafted functional groups. This study highlights the potential of PAM‐GPs as toughening fillers for epoxy composites, emphasizing their applicability in enhancing the durability and performance of structural components in industrial applications.Highlights Polyacrylamide (PAM)‐modified graphene platelets by a water‐based approach. A strong interface promoted exfoliation and dispersion of platelets. PAM‐modified platelets improved epoxy modulus and toughness. Fractographic analysis unveils toughening mechanisms.

Role of Minor Phase Morphology on Mechanical and Shape-Memory Properties of Polylactide/Bio-Polyamide Nanocomposite.

In situ-generated nanofibrillar polymer-polymer composites are excellent candidates for the production of polymer materials, with high mechanical and SME properties. Their special feature is the high degree of dispersion of the in situ-generated nanofibers and the ability to form entangled nanofiber structures with high aspect ratios through an end-to-end coalescence process, which makes it possible to effectively reinforce the polymer matrix and, in many cases, increase its ductility. The substantial interfacial area, created by the in situ formed fiber/matrix morphology, significantly strengthens the interfacial interactions, which are crucial for shape fixation and shape recovery. Using the polylactide/bio-polyamide (PLA/PA) system as an example, it is shown that in situ PA fibrillation improves the mechanical and shape-memory properties of PLA. The modulus of elasticity increases by a factor of 1.4, the elongation at break increases by a factor of 30, and the shape-strain/fixity ratio and shape recovery increase from 80.2 to 97.4% and from 15.5 to 94.0%, respectively. The morphology of the minor PA phase is crucial. The best result is achieved when a physically entangled nanofibrous network is formed.

Noble Metal‐Free High Entropy Perovskite Oxide with High Cationic Dispersion Enhanced Oxygen Redox Reactivity

AbstractHigh entropy perovskite oxide (HEPO) materials have received significant interest as efficient electrocatalysts owing to their chemical and structural stability, effective interaction of multiple metal active sites with the reaction intermediate species resulting in enhanced catalytic activity. The effect of high‐entropy strategy could achieve the regulation of the structural durability by tailoring the composition. Herein, we design a novel transition metal and rare‐earth metal based high entropy perovskite oxide (Co0.11Mn0.11Ni0.11Fe0.14La0.13Nd0.13Gd0.13Pr0.13)O3, showing superior catalytic activity in the oxygen reduction reaction (ORR) and also promising electrocatalyst in oxygen evolution reaction (OER). High degree of cationic dispersion in the lattice and multiple electrocatalytic active sites enhance the oxygen ion migration at the surface and facilitate electron transfer, manifesting good ORR performance. Notably, the as‐prepared high entropy material exhibits onset and half‐wave potential of 1.02 V and 0.89 V versus RHE, respectively, exceeding the performance of the benchmarked Pt/C catalyst in the ORR process with reasonable redox kinetics. Moreover, the material also presents faster kinetics with reasonably low overpotential and excellent electrochemical stability in the OER process as well. This study shows the viability of designing non‐precious high entropy materials as highly efficient oxide electrocatalyst by utilizing its broad compositional space.

STRENGTHENING OF THE SURFACE BY FRICTION

The study is devoted to the application of the method of surface hardening by friction Object of study - the process of surface hardening by friction.Subject of study - samples of 65G steel the method allows achieving high values of hardness, strength and wear resistance of materials in a short time and at much lower cost compared to other processing methods. The aim and objectives of the study are to investigate the nature of surface hardening of steel samples by friction. To achieve this goal, the following tasks are envisaged: manufacturing samples from 65G steel in the form of plates, preliminary heat treatment of samples for their maximum thermal hardening, hardening of the surface of samples by friction, analysis of the microstructure and microhardness of each sample, comparison of the microstructure, microhardness and depth of hardening of these samples, conclusions on the influence of processing factors on the hardening result. Based on the experimental data obtained, we constructed graphs of microhardness changes in the cross-section of the samples and studied the microstructures. It can be seen that after friction treatment, a layer with a modified structure is formed in the surface of the samples. The microhardness of the surface is significantly higher (approximately 2 times) than the microhardness of the main part in the samples. Metallographic analysis has shown that the layer formed in the samples has a martensitic structure characterized by a higher degree of dispersion and microhardness compared to the martensitic structure obtained during the previous heat treatment. Changes in the microstructure and microhardness of the samples that were surface hardened using different processing modes were compared. Certain differences in the characteristics of their hardened «white» layers were found. It is also shown that the hardened «white» layer is located along the entire length of the surface in the samples and is continuous and homogeneous.

ПОКАЗАТЕЛИ КАЧЕСТВА МОЛОКА И МОЛОЧНОЙ ПРОДУКТИВНОСТИ ПРИ ИСПОЛЬЗОВАНИИ ПРЕПАРАТА «ЙОДИНОЛ-ЯНТАРНЫЙ» В РАЦИОНЕ ЛАКТИРУЮЩИХ КОЗОМАТОК НУБИЙСКОЙ МЯСО-МОЛОЧНОЙ ПОРОДЫ

Proper nutrition is a prerequisite for normal physiological and mental development, as well as strengthening immunity to various adverse environmental factors. Goat milk products are especially relevant in baby food due to their unique properties. The reduced casein content in the fractional composition of proteins makes the products hypoallergenic, and the predominance of casein contributes to the rapid formation of a fine clot in the child's stomach. A high naive degree of fat dispersion facilitates and improves its assimilation, and also contributes to the assimilation of a large amount of polyunsaturated fatty acids that ensure the normal development and formation of the child's body. In addition, goat's milk contains a large amount of vitamins: A, C, B, PP, as well as trace elements: calcium, phosphorus, magnesium, cobalt. Providing children with high-quality balanced food is an important state task, the fulfillment of which is the key to the health of the nation. Since most regions of Russia are iodine deficient, they need the trace element iodine for life, which is why it is necessary to adjust the mineral composition of goat's milk. For the animals themselves, this is also relevant for the treatment and prevention of iodine deficiency. The influence of an energy-metabolic preparation based on iodine and succinic acid on the quality indicators of milk and milk productivity of lactating goats is considered. Literature data indicate an increase in the therapeutic effect when succinic acid is added to the active substance. In nature, there is a direct relationship between the iodine content in soil, water, plants and in the animal body. With insufficient intake of iodine with feed and water, the productivity, reproductive qualities, and genetic potential of animals decrease. Therefore, an urgent problem is to find ways to replenish iodine deficiency in the body of farm animals. In this regard, studies were conducted on the quality of milk of lactating goats of the Nubian meat and dairy breed when they were injected with a new drug "Iodinol-Yantarny". The effective effect of this drug on milk quality indicators in dairy goat breeding has been proven.

Vegetation–Topographic Landscape and the Influence of Water and Sediment in the Shule River Basin

The study of the effect of vegetation cover on water and sediment content is of great significance for the in-depth understanding of ecological and environmental effects in river basins and the formulation of corresponding management measures. Based on the monitoring data of rainfall and runoff of Panjiazhuang and Dangchengwan Hydrologic Stations in Shule River Basin from 2000 to 2020 and the sediment discharge of Changmabao, methods such as geographic information technology (GIS), landscape pattern analysis, land use transfer matrix, correlation analysis, principal component analysis, and linear regression analysis were used to study water and sediment change, land use pattern, vegetation change characteristics, and local water and sediment change in Shule River Basin and construct vegetation–topographic landscape factors. The main research results are as follows: (1) Vegetation coverage in the Shule River Basin increased year by year from 2000 to 2020, with a cumulative increase of 0.064 in 20 years. Vegetation cover has a significant effect on water and sediment content, and the correlation is −0.966. (2) The cultivated land area of the Shule River Basin increased by 604 km2 from 2000 to 2020, and the conversion rate was 67%. From 2000 to 2020, the water area increased by 442 km2, and the conversion rate was 51%. The area of grassland and forest increased by 198 km2 and 12 km2, respectively, and the conversion rate was 68% and 33%, respectively. Forest had the highest transfer rate (0.67). The lowest conversion rate was 0.32 for grassland. (3) The variation coefficient of water and sediment content in Shule River Basin during 1971–2020 was 45.21%, and the highest variation coefficient during 2001–2010 was 49.15%. The lowest variation coefficient was 39.73% during 2011–2020. The annual sediment transport in the Shule River Basin fluctuates greatly and has a high degree of dispersion during 1971–2020. (4) The results of the landscape index in Shule River Basin during 2000–2020 had a small difference, with a difference of less than 0.5. According to the principal component analysis of landscape index and water and sediment content, the maximum patch index (LPI) had the strongest positive correlation with water and sediment content (0.958). The diversity index SHDI had the strongest negative correlation with water and sediment content (−0.995).

The impact of pH and temperature on the green gold nanoparticles preparation using Jeju Hallabong peel extract for biomedical applications.

The utilization of gold nanoparticles (AuNPs) has garnered significant attention in recent times, particularly in the field of biomedical research. The utilization of AuNPs in chemical synthesis procedures raises apprehensions regarding their potential toxicity in living organisms, which is inconsistent with their purported eco-friendly and cost-effective aspects. In this investigation, AuNPs were synthesized via the green synthesis approach utilizing Jeju Hallabong peel extract (HPE), a typical fruit variety indigenous to South Korea. The visible-range absorption spectrum of gold nanoparticles from green synthesis (HAuNPs) that are red wine in color occurs at a wavelength of λ = 517 nm. The morphology and particle size distribution were analysed using transmission electron microscopy (TEM) and ImageJ software. The TEM images reveal that the HAuNPs exhibit a high degree of dispersion and uniformity in their spherical shape, with an average size of approximately 7 nm. Moreover, elevating the initial pH level of the mixed solution has an impact on the decrease in particle dimensions, as evidenced by the blue shift observed in the UV-visible spectroscopy absorbance peak. Elevating the reaction temperature may accelerate the synthesis duration. However, it does not exert a substantial impact on the particle dimensions. The outcomes of an avidin-biocytin colorimetric assay provide preliminary analyses of possible sensor tunability using HAuNPs. The cytotoxicity of HAuNPs was evaluated through in vitro studies using the MTT assay on RAW 264.7 cell lines. The results indicated that the HAuNPs exhibited lower cytotoxicity compared to both chemically reduced gold nanoparticles (CAuNPs).

Analysis of Production Risk in Intensive Chicken Farms – The Case of Kosovo

Abstract Research background The egg production sector in the poultry industry in Kosovo is well developed, with intensive chicken farms that meet 99% of domestic demand (MAFRD, 2021). However, this industry is not without risks. As such, this research investigates the production risks faced by intensive chicken farms. Purpose This study aims to investigate the severity of production risks and familiarize farmers with their levels. Research methodology Both qualitative and quantitative statistical methods were utilized in this study. Indicators are defined to measure the perception of farmers according to the Likert scale ranging from 1 (very low) to 5 (very high). A quantitative analysis is then performed to calculate the interval width, loss distribution, damage standard deviation, and coefficient of variation. Results The qualitative analysis reveals that farmers’ perceptions of production risks are not necessarily related to financial damages. The risk matrix is used to convey the levels and severity of production risks. The quantitative analysis shows that production risks have a high degree of dispersion (82.35%), a high standard deviation (€13,526), and a very high coefficient of variation (204%). Novelty This study is novel in that it is the first to explore production risks in the intensive chicken production industry in Kosovo. Previous studies have only focused on financial risk, market risk, legal risk and human resource risk.

THE EFFECT OF HIGH-TEMPERATURETREATMENT ON THE SORPTION PROPERTIES OF NATURAL BLUE CLAY

Relevance. Natural mineral clays are widely used not only in technology, but also in medicine, cosmetology, and the food industry, due to their unique properties. The high degree of dispersion, sorption-adhesive properties of clay materials, as well as the rich mineral composition also determine their therapeutic effect. Depending on the area and purpose of use, clays are subjected to heat treatment, which can lead to a change in their properties. The purpose of the work is to study the influence of various heat treatment modes on the sorption properties of clay for its further use in pharmaceutical practice. Material and methods. The object of study is Kimmeridgian blue powdery of clay blue Undory in the Ulyanovsk region. Determination of clay moisture content was carried out using an AND MF–5 moisture analyzer (Japan). To completely remove moisture from clay by high-temperature treatment, an SNOL 7.2/1100 electric furnace (Lithuania) was used. The influence of the clay calcination regime on the thermal stability of the clay powder and the ongoing endo- and exothermic effects with loss of sample mass was studied using a Q-1500D derivatograph (Hungary). Adsorption activity was assessed by direct spectrophotometry using an SF-56 “LOMO-Spectrum” spectrophotometer (Russia). Results. DTA of the derivatogram showed the thermal stability of the clay powder in the temperature range from 20°C to 900°C with variations in endo- and exothermic effects. Based on these data, heat treatment modes and sample exposure time were selected. The experiment showed a statistically significant decrease in adsorption activity with increasing temperature and various variations in exposure time. Conclusions. To preserve the adsorption properties of clay blue Undory when removing moisture from it, it is not rational to use high-temperature treatment. The most optimal parameters for drying clay are: temperature 80 ° C, exposure time - 240 minutes.

An eco-friendly method for the scale-up synthesis of ZSM-5 Zeolite

Scaling-up is the key step of the commercialisation of ZSM-5 zeolite, and the cost-effectiveness and greenness of the synthesis strategy is a decisive factor that cannot be ignored in the scale-up process. Herein, we present a template-free and solid-state-like crystallisation method for the synthesis of ZSM-5 zeolite by mechanical mixing of starting material components, which can be used for the scale-up production of ZSM-5 zeolite. The crystallisation range of ZSM-5 zeolite was obtained by this mechanical mixing of anhydrous starting materials. We have analyzed the kinetics study of three different Na2O/Al2O3/SiO2 systems in the range, and obtained the trends of nucleation and growth activation energy. The results show that mechanical mixing can effectively achieve a high degree of homogenous dispersion of the starting material, which is conducive to obtaining ZSM-5 with high crystallinity and size uniformity. We have synthesised monolithic ZSM-5 with high crystallinity and uniform grain size of about 2 g, 30 g and 120 g in different sizes (2.5 ml/50 ml/200 ml) of Teflon lined high pressure reactors in a single synthesis method. This study affirms the possibility of achieving the scale-up of ZSM-5 zeolite synthesis through the synthetic pathway proposed, presenting a cost-effective, eco-friendly strategy for the industrial preparation of ZSM-5 zeolite.

Spatial structure modulation of Poly(ionic liquid)s with hierarchical porous structure for efficiently catalytic conversion of CO2 into cyclic carbonates

Among the many resource utilization routes of CO2, the reaction of CO2 with epoxides to synthesis cyclic carbonates is a well-established method, which is not only environmentally friendly but also in line with atomic economy for heterogeneous catalysts. Aimed at insufficient exposure of active sites and poor catalytic activity, a series of P[VImX][Br] Poly(ionic liquid)s (PILs) catalysts was developed with different porous structure. PILs catalysts with hierarchical porous structure and particle size were obtained by adjusting the ratio of ILs and DVB monomer. When the ratio of ILs increased, the specific surface area and the degree of dispersion of the particles firstly increased and then decreased, and the larger specific surface area and the degree of dispersion were more favorable for the full exposure of the active sites, which in turn improved the catalytic activity. Among them, the optimal ratio of ILs is 0.4 (P[VIm0.4][Br]), which has relatively large specific surface area and high degree of dispersion, and the highest catalytic activity, and the conversion rate of propylene oxide (PO) reaches 95 %. In addition, the catalyst exhibited good recoverability after five cycles and obtained a wide substrate applicability. This paper provides a new idea for tuning the structure of PILs for high efficient catalysis.

Thermal resistance of steels with increased strength properties for pressure vessels of advanced VVER reactors of various designs

The paper considers the results of structural studies and mechanical tests after a long-term thermal exposure of laboratory heats of the metallurgically improved 15Kh2NMFA steel and steel with an increased content of nickel considered as materials for the pressure vessels of advanced VVER-type reactors of various designs. It has been shown that, both for the improved 15Kh2NMFA steel and the high-nickel steel, there are no signs of grain boundary embrittlement after an segregation provoking embrittlement heat treatment. This is explained by the extremely low grain boundary segregation of phosphorus in the initial state caused by a high degree of the structure dispersity as well as by rather a low content of impurities. Besides, no changes have been found in the yield strength value for the improved 15Kh2NMFA steel, which agrees with the structure investigation results. For the high-nickel steel, a tendency towards a minor yield strength decrease by 5 to 10% and a regular reduction of the critical brittleness temperature has been revealed. A decrease in the mechanical properties has been caused by a relatively low temperature of tempering for the high-nickel steel and, accordingly, by the potential occurrence of the structure recovery during long-term thermal exposure, as evidenced by the results of an X-ray diffraction analysis. Despite the structure recovery in the high-nickel steel under the long-term thermal exposure, the main strengthening carbide phases remain stable. Due to this, the yield strength value remains at a relatively high level that exceeds the values for the modern VVER-type vessel steels, even in the case of a thermal exposure much in excess of the expected operating conditions for advanced VVER reactors. The observed decrease of critical brittleness temperature during the long-term thermal exposure contributes to an increase in the steel resistance to brittle fracture.

Novel approach for synthesis of highly active nanostructured MgO/ZnAl2O4 catalyst via gel-combustion method used in biofuel production from sunflower oil: Effect of mixed fuel

A series of MgO/ZnAl2O4 nanocatalysts was prepared in order to conversion of sunflower oil to green fuel through transesterification reaction. The ZnAl2O4 spinel was synthesized using combustion method with different mixtures of urea and citric acid as fuel. MgO was also loaded on the catalysts as the active phase by impregnation method. the physicochemical properties of synthesized MgO/ZnAl2O4 nanocatalysts was evaluated with TGA/DTG, XRD, FESEM, EDX-dot mapping and nitrogen adsorption–desorption technique. XRD patterns of all samples showed crystalline phase of zinc aluminate without any impurities. The porous morphology as well as high degree of active phase dispersion was observed in samples prepared with mixed fuel. Using mixed fuel with urea to citric acid ratio of 0.5 led to create more pores in range of 10–20 nm. It is worth mentioning that the results of the catalytic performance test of the synthesized catalysts revealed that the highest conversion rate of 98.45 % was obtained in the synthesized sample with a ratio of urea to citric acid of 1:2. Furthermore, this sample illustrated superb stability in the reusability examination so that even over after five recovery cycles, the conversion triglyceride just decreased to 91.1 %.

Temporal dynamics of mother-offspring relationships in Bigg's killer whales: opportunities for kin-directed help by post-reproductive females.

Age-related changes in the patterns of local relatedness (kinship dynamics) can be a significant selective force shaping the evolution of life history and social behaviour. In humans and some species of toothed whales, average female relatedness increases with age, which can select for a prolonged post-reproductive lifespan in older females due to both costs of reproductive conflict and benefits of late-life helping of kin. Killer whales (Orcinus orca) provide a valuable system for exploring social dynamics related to such costs and benefits in a mammal with an extended post-reproductive female lifespan. We use more than 40 years of demographic and association data on the mammal-eating Bigg's killer whale to quantify how mother-offspring social relationships change with offspring age and identify opportunities for late-life helping and the potential for an intergenerational reproductive conflict. Our results suggest a high degree of male philopatry and female-biased budding dispersal in Bigg's killer whales, with some variability in the dispersal rate for both sexes. These patterns of dispersal provide opportunities for late-life helping particularly between mothers and their adult sons, while partly mitigating the costs of mother-daughter reproductive conflict. Our results provide an important step towards understanding why and how menopause has evolved in Bigg's killer whales.

Thermal Decomposition of H2S at Low Temperature on Mo-Containing Catalysts Derived from MAlO (M = Mg, Co, and Ni) Layered Double Hydroxides

It is increasingly attractive to simultaneously recover the resources of hydrogen and sulfur by catalytic decomposition of hydrogen sulfide (H2S). Restricted by the low yield and high reaction temperature, searching for materials with excellent catalytic activity and stability on thermal decomposition of H2S is significant. A high dispersion and sulfidation degree of MoS2 phases with a promoter (Co or Ni) were prepared with the help of interaction between the layers of hydroxides (CoAl or NiAl) and Mo anions. The NiAlMo-s catalysts exhibited outstanding catalytic activity at 500 °C with H2 yield reaching 49.6%. Several characterizations verified that the excellent performance resulted from the Lewis acid on the surface. Accumulation of sulfides reduced stability, while generation of NiMoS contributed to good stability. Generally, these results will be beneficial to enrich the theory of designing H2S decomposition catalysts. Also, these findings will offer potential application of the resource recovery technology on H2S decomposition.

Optimization of fluid flow in membrane chromatography devices using computational fluid dynamic simulations

Flow uniformity within the device is critically important in membrane chromatography. Recent studies have shown that the design of the device has a significant impact on flow uniformity, and thereby on separation efficiency. The main premise of this work is that computational fluid dynamics (CFD) could serve as a fast and inexpensive tool for preliminary optimization of the design of a membrane chromatography device. CFD also helps in identifying factors that affect flow uniformity. In this paper, CFD is used to compare the fluidic attributes of conventional membrane chromatography devices such as the stacked disc and radial flow devices with those of more recently developed ones such as the different versions of the laterally-fed membrane chromatography (LFMC) device. These are compared based on pulse tracer solute dispersion, which is a useful metric for measuring flow uniformity, and is thereby a good predictor of chromatographic separation performance. The poor separation performance typically observed with conventional membrane chromatography devices could be attributed to the high degree of solute dispersion within these devices. CFD is then used to analyze the impact of factors such as membrane aspect ratio, and channel dimensions on the performance of z2-laterally-fed membrane chromatography (z2LFMC) devices. The results discussed in the paper demonstrate that CFD could indeed serve as a powerful optimization and performance prediction tool for membrane chromatography.

Highly dispersed Pt clusters within ZSM-5 stabilized by alkali metal ions and Al sites for partial methane oxidation

Zeolite is an ideal material to encapsulate nanoparticles and avoid metal aggregation, but it is challenging to achieve a high degree of metal dispersion inside zeolite. In this work, the Na+ reagent was introduced to synthesize Pt@S-1 and Pt@ZSM-5 to explore the effect of Al sites and alkali metal ions on dispersion of Pt nanoparticles. The properties of four catalysts were characterized by XRD, TEM, CO-TPR, TG and FT-IR, and the effects of alkali metal ions were analyzed combined with POM test results. The introduction of a certain amount of alkali metal ions in Pt@ZSM-5 catalyst consumed part of the hydroxyl group to form stable Pt-Ox(OH)yNa active species, which further improves the stability and dispersity of platinum nanoparticles and promotes the activity of partial oxidation of methane. This stabilization strategy can be extended to other porous materials encapsulating metal nanoparticles.