High Chemical Activity Research Articles

Structure, stability, electronic and magnetic properties of monometallic Pd, Pt, and bimetallic Pd-Pt core–shell nanoparticles

The structure, stability, electronic and magnetic properties of 13-, 33- and 55-atom Pd, Pt monometallic and bimetallic core–shell nanoparticles (BCSNPs) were investigated using the density functional theory calculations. The results showed that Pt@Pd BCSNPs with a Pd surface-shell are thermodynamically more favorable than Pd@Pt with a Pt surface-shell. Interestingly, 33-atom three-shell Pd@Pt12@Pd20 was more stable than two-shell Pt13@Pd20, while two-shell Pd13@Pt20 was more stable than three-shell Pt@Pd12@Pt20. 55-atom three-shell Pd@Pt12@Pd42 and Pt@Pd12@Pt42 were more stable than two-shell Pt13@Pd42 and Pd13@Pt42. The Pd@Pt BCSNPs with Pt surface-shell exhibited a negative charge, d-band-center upshift and high chemical activity, while the Pt@Pd BCSNPs with Pd surface-shell displayed a positive charge, d-band center downshift and low chemical activity. 13- and 55-atom NPs with Pd surface-shell displayed higher total magnetic moment than those with Pt surface-shell except Pd13@Pt20. 33-atom NPs with Pt surface-shell afforded higher total magnetic moment than those with Pd surface-shell.

Исследование поверхности хлопковых волокон после термической переработки в вакуумной камере методом сканирующей электронной микроскопии

The article presents the results of a study of the surface of cotton fibers before and after thermal processing in a vacuum chamber by scanning electron microscopy. It has been established that various factors affect the structural and physicochemical properties of an ultrathin composite material based on ultra-dispersed carbon fiber. In this work, the microstructures of an ultrathin composite material obtained based on ultrafine cotton fibers were investigated and a chemical analysis of these fibers was carried out. Based on chemical analysis, it was found that the content of heat-treated cotton fiber is 98.62% during heat treatment (from 1000 to 1200 °C). Along with this, the resulting powder had carbon fibers with sizes from 2.42 to 9.18 μm, and thus ultra-thin fibers have high chemical activity. It is shown that heat treatment of the fiber leads to molecular bonding of the outer layer of the cotton fiber.

Phase assemblage and wear resistance of laser-cladding Al0.8FeCoNiCrCu0.5Six high-entropy alloys on aluminum

Preparing a coating with excellent mechanical properties on aluminum substrates by laser cladding has always been challenging because of the low melting point and high chemical activity of Al. In this study, we designed Al0.8FeCoNiCrCu0.5Six (x = 0, 0.2, 0.3, 0.4, and 0.5) high-entropy alloys (HEAs) as cladding materials. The proposed study aims to exploit the unique high-entropy effect of HEAs to restrict the the formation of hard and brittle intermetallic compounds via the reaction between Al in the substrate and added powders, thereby enhancing the quality of the formed coatings and ultimately improving the surface properties of the Al alloy. Results show that with an increase in the Si content, the structure of the Al0.8CrFeCoNiCu0.5Six coating changes from FCC + BCC1 + BCC2 to BCC1 + BCC2. The hardness of the Al0.8FeCoNiCrCu0.5Six coating first increases and then decreases with an increase in the Si content. The coatings with the highest and lowest hardness were those with compositions of Al0.8FeCoNiCrCu0.5Si0.4 (592HV0.2) and Al0.8FeCoNiCrCu0.5 (412HV0.2), respectively, which is approximately seven and five times greater than that of the substrate, respectively. The effect of Si content on the wear resistance of the coating is the same as its effect on the hardness. The wear rates of coatings with different Si contents range from 1.19 × 10−6 mm3 Nm−1 to 8.99 × 10−7 mm3 Nm−1 and are only 0.34% to 0.25% of the substrate. Obvious, the Al0.8FeCoNiCrCu0.5Six HEAs can be used as coating materials to improve the mechanical properties of an Al alloy surface.

Microplasma-Sprayed V2O5/C Double-Layer Coating for the Parts of Mini-Hydropower Systems

The development of novel designs for hydropower plants is of high interest nowadays. Studies have shown the negative effect of fluid flow on the turbines of mini-hydropower plants when using them in the conditions of the mountain river. To reduce the damage caused by cavitation, a microplasma coating technique has been chosen. Due to its wetting ability, low density, high thermal conductivity, high heat resistance and low chemical activity, graphite has been studied as a coating material. Vanadium pentoxide has been added as an interlayer to increase the wear resistance, corrosion resistance, and adhesion of the system. The microstructure of the system was studied using scanning electron microscopy and transmission electron microscopy. Functional properties of the system were tested by microhardness tests, wear resistance tests (friction), corrosion tests, and pull-off tests. The surface of the coating was homogeneous without warping, swelling and cracking. The microstructure consisted of regular structures in the form of branches of dendrites. V2O5/C coating resulted in the increase in microhardness up to 2534 MPa. The wear resistance (volume loss) of the sample with double-layer coating was 0.14 mm3 and the maximum adhesion strength was 17.5 MPa. Thus, the double-layer microplasma V2O5/C coating was applied and studied for strengthening the blades of mini-HPP. The microplasma method can find application in modifying the surface of power equipment subjected to the cavitation effect of the river water.

Superior extreme pressure properties of different layer LDH nanoplatelets used as boundary lubricants

Layered double hydroxides (LDHs) are a class of strongly adsorbed two-dimensional materials composed of divalent and trivalent metal cations. In this study, LDHs nanoplatelets with three different thickness were synthesized by changing the crystallization method during the hydrothermal reaction process. The three-dimensional size and layer number of nanoplatelets were confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The synthesized ultrathin Co/Al-LDH (U-CA-LDH) nanoplatelets, only ca. 1 nm thick (single or double layer), were surface modified with ethylene glycol for good dispersion in an oil-based system. As a lubricant additive, the base oil with U-CA-LDH nanoplatelets can withstand extreme pressures of up 2000 N, almost three times the ultimate load-bearing capacity for commercial additives. In particular, through physical property and chemical composition analysis of tribofilms, U-CA-LDH nanoplatelets with a partial tetrahedral coordination form were revealed to exhibit better tribological properties than multilayer Mg/Al-LDH (M−MA−LDH) nanoplatelets with a stable octahedral coordination form. Incomplete coordinated nanoplatelets exhibited extremely high chemical activity in the high-temperature tribological region and promoted the formation of a denser protective tribofilm on the sliding surface. Owing to their superior tribological properties as oil-based additives, U-CA-LDH nanoplatelets hold great potential for practical application in the mechanical industry in the future.

Thermal stability and microstructure of metakaolin-based geopolymer blended with rice husk ash

Thermal stability of metakaolin -based geopolymer blended with rice husk ash with replacement levels of 5–20% by weight of MK was investigated. The phase composition, thermal stability and microstructure of geopolymer before and after high-temperature exposure were explored by using X-ray diffraction(XRD), Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectrometer (FTIR), BET specific surface area test (BET) and Scanning electron microscope (SEM). The optimum chemical activity of rice husk ash can be obtained when calcined at 600 °C for 4 h. The addition of rice husk ash increases the compressive strength of geopolymer by accelerating the alkali-activated reaction process. The compressive strength at 28 days of curing increases by 24% with 15 wt% rice husk ash. The porous rice husk ash accelerates the discharge of water vapor from geopolymer and protects geopolymer from cracking caused by air pressure. The high chemical activity of rice husk ash accelerates the high-temperature geopolymerization process and contributes to the healing of microcracks. Rice husk ash reduces the melting sintering temperature of geopolymer from 870 °C to 780 °C, improves the formation of compact ceramic protective layer and prevents the high temperature spalling of geopolymer.

Hydrochemical characterization of abandoned quarry and mine water for domestic and irrigation uses in Abakaliki, southeast Nigeria

The Abakaliki area has been renowned for lead–zinc mining and hard rock quarrying, and these activities generate acid mine drainages (AMDs) and chemical dissolution of minerals into the water, respectively. This research is aimed at assessing the influence of AMDs and other dissolved elements on water quality for domestic and irrigation uses in the area. Thirty-five water samples were collected and analyzed for physicochemical parameters, including: pH, total dissolved solid, electrical conductivity, major cation and anion and heavy metals using atomic absorption spectrophotometric methods. Mathematical calculations were used to deduce irrigation parameters. Result indicates that pH of water samples is slightly basic to acidic, and EC ranges from 5.28 to 1492 µS/cm. Only samples around Nigercem, Nkalagu and lead–zinc mines at Enyigba were above WHO permissible limit for drinking water. The concentrations of Na+, K+, Ca2+, Mg2+ and HCO3− were within WHO set standard for drinking water, while Cl− and SO42− were above the WHO set standard. Irrigation parameters showed soluble sodium percentage between 8.33 and 100.00, sodium percentage ranges between 2.77 and 300.00%, Kelly ratio ranges from 0.03 to 3.00, magnesium absorption ratio ranges between 16. 92 and 123.5, total hardness ranges between 3.00 and 125.0, residual sodium bicarbonate ranges between − 23.84 and 0.11, and potential salinity ranges from 2.93 to 14.77 within the study area. Abandoned mine water in the area is fairly suitable for irrigation uses, but unsuitable for domestic uses. This is due to high chemical activities taking place in the mine ponds, and these 17 ponds have been abandoned for over 2 decades. Deductions from Soltan classification revealed that 98% of groundwater falls within deep meteoric water.

Metal organic framework coated MnO2 nanosheets delivering doxorubicin and self-activated DNAzyme for chemo-gene combinatorial treatment of cancer.

The RNA-cleaving DNAzyme (DZ) holds promising potential for RNA interference (RNAi) applications and is favored over siRNA owing to its high chemical stability, biocompatibility, predictable activity, and substrate versatility. However, its pharmaceutical applications for disease treatment are limited by the requirement of metal cofactor for activation, as well as the lack of effective co-delivery systems to combine with other therapeutic modalities. Herein, we designed and constructed metal organic framework (MOF) coated MnO2 nanosheets to realize the co-delivery of a survivin inhibiting DZ and doxorubicin (DOX) for chemo-gene combinatorial treatment of cancer. In our design, the DOX was adsorbed on MnO2 planar surface, and the DZ was loaded into the MOF shell layer through the coordination between Mn2+ and tannic acid. The nano-system could stably encapsulate the payloads under physiological condition, but rapidly degraded after endocytose into tumor cells in response to intracellular stimuli, resulting in triggered drugs release. Notably, the coreleased Mn2+ could act as metal cofactor for effective DZ activation. Both in vitro and in vivo studies have demonstrated the enhanced anti-tumor efficacy of the nanosystem, with co-contributions from anti-neoplastic DOX, survivin silencing effect of DZ, and to some extent, ROS generation by Mn2+. This work provides an ingenious strategy to address the key limitation of DZ for RNAi applications and realize the combination of DZ with other therapeutic modalities, in which the DZ can be in-situ activated for target gene silencing.

Vacancy defected blue and black phosphorene nanoribbons as gas sensor of NOx and SOx molecules

Black phosphorene, due to its high chemical activity and large surface-to-volume ratio, indicates potential application for gas sensing. Additionally, recently synthesized blue phosphorene has attracted a lot of attention because of its properties, appropriate for applications in different fields. In this work, the sensing properties of vacancy defected black and blue phosphorene nanoribbons for NOx and SOx molecules are analyzed with density functional theory. Adsorption energy and adsorbate/phosphorene distance are studied for sensing molecules on pristine black/blue phosphorene nanoribbons which show the sensing capability of these materials. In order to further develop the sensor performance, considering the vacancy defect in the host material is suggested. Due to comprehensively analysing the effect of vacancy defect in the terms of sensor response, the I-V characteristics of defected blue/black phosphorene-based FET structures are calculated. Calculation results confirm that, vacancy defect increases the adsorption energies of all examined molecules on phosphorene-based substrates but calculated I-V values show small changes in current responses of armchair black/blue phosphorene nanoribbons in both pristine and defected forms. However, in the case of zigzag phosphorene nanoribbons, great current modifications before and after sensing process are obtained. Consequently, our results present a promising application of vacancy defected zigzag phosphorene nanoribbon in gas sensing.

Microstructure, solidification behavior and mechanical properties of Al-Si-Mg-Ti/TiC fabricated by selective laser melting

Ball-milled Ti/TiC composite particles (TiC nanoparticles assembled on Ti microparticles) were designed, prepared, and mixed with Al-Si-Mg powder to fabricate an Al-Si-Mg-Ti alloy with TiC nanoparticles (Al-Si-Mg-Ti/TiC) by selective laser melting (SLM). Microstructure features, solidification behavior, and mechanical properties were investigated, and the relationship among them was established. The SLM-manufactured Al-Si-Mg-Ti/TiC material exhibited fine equiaxed-shaped α(Al) grains with nanoscale Si4Ti5 phases and Mg segregation along the grain boundaries. This structure benefited from heterogeneous nucleation as well as the grain growth restriction capabilities of TiC nanoparticles on α(Al), fast diffusion of Ti in the superheated Al liquid, and high chemical activity of Ti to Si during solidification. Furthermore, Ti enrichment in some local areas of the high-temperature pool and the consequently intense Marangoni convection improved the wettability between TiC nanoparticles and liquid Al without the interfacial reaction. Consequently, the SLM-manufactured Al-Si-Mg-Ti/TiC showed a high ultimate tensile strength of up to 562 ± 7 MPa and an elongation of up to 8.8 % ± 1.3 % before fracture. These increased mechanical properties are attributed to the combined effect of grain refinement and Orowan and load-bearing strengthening mechanisms.

Synergistic Action of Sulfate and Chloride Anions on the Corrosion Behavior of AZ31B Magnesium Alloy

Magnesium and its alloys have a great potential for lightweight structure applications, because magnesium has lower density (~1.7 g.cm-3) compared to aluminum (2.7 g.cm-3) and iron (~7.9 g.cm-3). Magnesium alloys also exhibit high strength-to-weight ratios [1]. Their use enables the weight reduction of automotive and aerospace vehicles for more energy consumption efficient. However, magnesium alloys have a limitation for practical application, namely the high chemical activity, porous corrosion product and high corrosion rate. In addition, due to the rapid industrialization in some developing countries, air pollution (like PM2.5) has become a hot topic. Most of air pollutants contain ions like SO4 2-, NO3- and NH4+, which have high solubility [2]. The corrosion behavior of magnesium in chloride-containing environment is also worth studying because Cl- is the most common aggressive corrosion species. In contrast, sulfate ions in chloride-containing solutions can inhibit hydrogen evolution [3]. It is thus of great interest to understand the corrosion behavior of magnesium alloys in solution containing different anions, which provides a basis for designing the effective conversion coating process.In this study, the corrosion behavior of magnesium alloy AZ31B in sulfate and chloride solutions was investigated by using real-time imaging, hydrogen evolution test, electrochemical analysis, and cross-sectional TEM characterization. Through the results of the real-time imaging, the corrosion behavior of magnesium alloy AZ31B in the solution can be roughly divided into three stages. Firstly, the uniform corrosion proceeds with a large amount of hydrogen evolution. Secondly, the corrosion product gets thicker accompanied by the reduction in the amount of hydrogen evolution. Final stage only happens in the chloride containing solution. A hydrogen stream and dark corrosion products are produced [4]. Cross-sectional TEM was employed to characterize the sample, which was immersed for 25 min (the time when the dark corrosion product was produced). The results show that when the magnesium alloy AZ31B was treated in the chloride solution, the thickness of the corrosion product layer is about 80 ± 30 nm. Furthermore, the corrosion product layer formed in a sulfate-containing solution shows a uniform film thickness about 170 nm. This difference in thickness was further confirmed in the hydrogen evolution test. The hydrogen evolution test shows that the amount of hydrogen produced by the magnesium alloy AZ31B in the sulfate solution is about twice that in the chloride solution. This indicates that the corrosion product formed in the sulfate solution is about twice that in the chloride solution, implying that the corrosion product formed in the chloride ion environment is more protective. The EIS results also show the same trend. The total impedance of the corrosion product in the chloride ion immersion environment is much larger than that of the sulfate solution and the total impedance value increases as the chloride concentration is increased. As a result, chloride ions can effectively fill the weaker areas of the airform film during the early stages of corrosion. This localized corrosion phenomenon also causes the difference in film thickness.The third stage of corrosion was found to be absent when the magnesium alloy AZ31B was immersed in a chloride and sulfate mixture solution. The TEM results show that the corrosion product is more uniform than immersed in solution containing only chloride. Thus, it is proposed that sulfate ions serve as a physical barrier to hinder chlorine ions from attacking the magnesium substrate, which, in turn, results in a uniform corrosion product layer.

Corrosion Resistance of Zinc Phosphate Conversion Coatings on AZ91D Surface

Magnesium alloys have been widely applied in many fields, because of their high strength-to-weight ratio. However, magnesium alloys have high chemical activity and are easily corroded. The poor corrosion resistance of magnesium alloys greatly limits its further application. In this paper, the zinc phosphate conversion coatings were prepared on the surface of AZ91D magnesium alloys. Nano-zinc oxide was the source of zinc and the zinc phosphate conversion coatings were prepared by the given process: 1.25 g/L NaNO3, 3 g/L C6H8O7 H2O, 2.5 g/L NaF, 5.5 g/L ZnO, 12.5 mL/L H3PO4, reaction temperature 50°C, reaction for 30 minutes. The full immersion uniform corrosion test was conducted for the fabricated coatings. The morphology and composition of corrosion in different corrosion stages were characterized by XRD, SEM and other microscopies. The results showed that: (1) the corrosion process of the conversion coatings could be divided into three stages: the dissolution of the conversion coatings, the corrosion of the matrix and the deposition of insoluble matter; (2) XRD analysis and other methods found that the pine-needle magnesium oxychloride compounds were formed in the process of immersion firstly, and it was dissolved into Mg(OH)2 over time; (3) With the extension of immersion time, Mg(OH)2 increased continuously and played a major role in corrosion prevention. The deposited Mg(OH)2 was divided into two layers. In the initial deposition stage, it was mainly evenly dispersed on the surface of the alloy to form a tightly arranged inner layer. Afterwards, the crystals of Mg(OH)2 agglomerated and formed a sphere, becoming the outer layers.

Valorization of dredged sediments in self-consolidating concrete: Fresh, hardened, and microstructural properties

Several studies have proven the use of dredged sediments as supplementary cementitious materials (SCMs), but limited information is available on the effect of such treated sediments on self-consolidating concrete performance. The main objective of this study was to evaluate the performance of self-consolidating concrete (SCC) fabricated with treated sediments. The sediments were thermally treated at 800 °C for 1 h. The packing density of the granular skeleton was optimized to reduce the paste content and produce SCC with relatively low binder content. Three different SCC mixtures were prepared with 0%, 10%, and 20% cement replaced with treated sediments by mass. Key fresh, physical, hardened, and microstructural properties of the investigated SCC mixtures subject to different curing regimes were evaluated. The test results showed that the optimized SCC mixtures exhibited adequate self-consolidation characteristics. The particle size and high chemical activity of the sediments led to pore refinement of micro-pores, increased density, improved microstructure, and reduced micro-cracks of the investigated SCC mixtures. Furthermore, the use of up to 20% of treated sediments resulted in a compressive strength of 66 ± 1 MPa at 91 days, which is comparable to that of the reference mixture made without any sediments. Leaching test results confirmed the ecological potential of producing SCCs based on sediments, which could be an interesting alternative of using local materials to reduce the high demand of cement, thus further reducing the CO2 footprint of concrete structures.

CHITOSAN APPLICATION IN FOOD TECHNOLOGY: A REVIEW OF RESCENT ADVANCES

The review focused on global trends in the development of scientific research and the practical applications of chitosan in food technology in recent years. Chitin and its derivative chitosan obtaining from the crustacean shells and the cell wall of fungi are among the most common biopolymers in the world. Chitosan is a polysaccharide discerned by a large number of unsubstituted amino groups. Featured properties of chitosan providing its high chemical and biological activities. Chitosan has various abilities as polycationite, film former, antimicrobial and antioxidant agent. Multifunctional properties open up broad prospects for the chitosan applications in various fields of technology, medicine and industry. The most attention in the review is paid to the works on extending food products shelf life with chitosan based primary edible film coatings and biodegradable packaging. At the same time chitosan applications as an emulsifier, a flocculant, as well as functional food additive, nutrient encapsulating material and dietary supplement are highlighted.

Characteristic of dissolved organic matter polar fractions with variable sources by spectrum technologies: Chemical properties and interaction with phenoxy herbicide

Dissolved organic matter (DOM) is ubiquitous with high biological and chemical activity. The large intake of DOM from compost, plant residues or soil can modify the behaviors of agrochemicals. Phenoxy herbicide is the third widely used herbicide around the world with both aromaticity and polarity. However, how the diverse fractions of DOM interacting with phenoxy herbicide and the underlying mechanisms remain unknown. Thus, it is crucial to investigate the heterogeneous chemical properties of DOM fractions from variable sources and explore the interactive mechanisms. In this study, polar DOM derived from compost, rice straw and soil were fractionated, and the chemical properties of fractions were analyzed by spectrum technology and the complex interaction with phenoxy herbicide was assessed by infrared spectroscopy. Results showed that hydrophobic acid (HOA) was the largest component (49.6%) in compost DOM, while hydrophilic matter (HIM) was the main component in the polar DOM from rice straw and soil. The 4-chloro-2-methylphenoxyac etic acid (MCPA) as one representative of phenoxy herbicides was used in our study, and the results showed the interaction between different DOM fractions and MCPA was heterogeneous. HOA containing abundant fulvic-like component and polar groups resulted a greatly complex interaction with MCPA mainly via hydrophobic force, ligand exchange and hydrogen bonding. Hydrophobic neutral fraction and acid-insoluble matter showed a medium interaction with MCPA as a result of enrichment with the high aromatic humic-like molecules. Inversely, no significant interaction between HIM and MCPA was observed. Our research revealed that the aromatic framework associated with polar groups in DOM dominated the interaction with phenoxy herbicide, which might affect the bioavailability, toxicity, and mobility of phenoxy herbicide.

Balancing oxygen-containing groups and structural defects for optimizing macroscopic tribological properties of graphene oxide coating

Graphene oxide (GO) coating is a potential candidate for improving friction-reduction and wear-resistance capabilities of moving mechanical systems. However, GO coating with diversity of oxygen-containing groups and defects on GO nanosheets dramatically affect its lubrication application. In this work, a facile, green, and ultrafast self-assembly method based on metal coordination interaction has been developed to construct lamellar GOCr coatings. Moreover, hydrazine vapor reduction was selected to tune the oxygen-containing functional groups and defects in a controllable manner while with minimal damage to the substrate. The macro-tribological behavior of the prepared coatings is investigated in both air and vacuum environments to explore the roles of oxygen-containing functional groups and defects on their tribological performances. The results show that, the oxygen-containing functional groups and unstable defect sites with high chemical activity can form hydrogen bonds with water molecules in air, leading to quick lubrication failure. Therefore, the prepared coating exhibits the best lubrication performance when the oxygen-containing functional groups and defects on GO nanosheets reach an optimal balance. In contrast, the lubrication performance of all coatings in vacuum is better than that in air environment, strongly demonstrating that the lubrication property is mainly influenced by defects due to the absence of water molecules in vacuum environment.

Spectroscopic characteristics of water-extractable organic matter from different green manures1

ABSTRACT Water-extractable organic matter (WEOM) plays an important role in many chemical processes and in soil organic matter accumulation. Large amounts of WEOM can be released by green manure when being incorporated into the soil. However, the characteristics of WEOM extracted from different green manures (GMs) are unclear. In this study, WEOM samples were extracted from Chinese milk vetch (Astragalus sinicus L), radish (Raphanus sativus L), ryegrass (Lolium perenne L), hairy vetch (Vicia villosa L), February orchid (Orychophragmus violaceus) and rye (Secale cereale L) and their characteristics were studied by spectroscopic analysis. WEOM generated from legume GMs contained more water-extractable organic carbon (WEOC) than other GMs and Chinese milk vetch was the highest. UV-visible spectroscopy analysis revealed that all the samples were rich in C=C and C=O functional groups. Carboxylic acid, alcohol, phenol, fatty acids, aliphatic aromatic and amide compounds were found by FTIR spectroscopy in these WEOM samples. WEOM derived from Chinese milk vetch contained more carboxylic acid and inorganic sulphates only appeared in WEOM extracted from the radish. The aromaticity index, humification index, and FTIR absorption ratio 1650/2925 and 1650/2850 showed that WEOM extracted from Chinese milk vetch and hairy vetch had a relatively lower aromaticity and humification degree than other GMs. The fluorescence regional integration (FRI) analysis showed that Chinese milk vetch and hairy vetch had a higher portion of protein-like substance fractions than other GMs. We may deduce that WEOM generated from Chinese milk vetch and hairy vetch has higher chemical activity than other GMs.

Adsorption of SO2 and NO2 molecule on intrinsic and Pd-doped HfSe2 monolayer: A first-principles study

HfSe2 monolayer with high electron mobility and chemical activity is a good candidate for gas sensing application. Pd-doping with high catalytic performance would effectively enhance the adsorbing and sensing behaviors of HfSe2 monolayer upon target gas molecules. In this work, we using first-principles theory investigated the adsorption performance of intrinsic and Pd-doped HfSe2 (Pd-HfSe2) monolayer upon two toxic gases (NO2 and SO2), to explore their possible application as gas sensors. Our results indicate that Pd-HfSe2 monolayer has desirable adsorption performance upon NO2 molecule compared with SO2 molecule, with higher adsorption energy and charge-transfer, which leads to more sensitive electrical response for NO2 detection. Moreover, the good desorption behavior of Pd-HfSe2 monolayer upon NO2 molecules allows its recycle use as a resistance-type NO2 gas sensors. Thus, we suggest the exploration of Pd-HfSe2 as a novel sensing material for NO2 detection, which would provide some guidance for experimentalists to further investigate its sensing behavior upon NO2. Our work would be meaningful to propose novel sensing materials from the theoretical manner.

A second species of the genus <i>Thermochiton</i> Saito et Okutani, 1990 (Mollusca: Polyplacophora)

The paper describes a new species of the genus , sp. nov., found in deep waters off Papua New Guinea. This species differs from primarily in the dorsal scales, the marginal spicules, sculpture of the jugal area and the shape of the central teeth of radula. There are apparent similarities between the species of the genus Thermochiton , Connexochiton platynomenus , C. kaasi and Ischnochiton crassus. The last species is proposed to be transferred to . Owing to the friable, rusty brown deposits that densely cover the shell and girdle of both specimens of , the latter probably lives in areas of high chemical activity.

Lifecycle of cobalt-based alloy for artificial joints: From bulk material to nanoparticles and ions due to bio-tribocorrosion

The release of debris and ions from metallic artificial joints during bio-tribocorrosion posed a severe threat to patient health. In this work, the lifecycle of a CoCrMo alloy was presented by investigating the subsurface microstructure transformation in-vitro. The results showed that the originally coarse grains changed to nano-grains (NGs) on the top region of the alloy, and nanoparticles (NPs) were torn off the surface, which were then blocked by the tribo-film. The agglomerated alloy NPs contained in the tribo-film transformed into debris after being removed from the alloy surface. The majority of the torn-off NPs were corroded and released ions into solution due to their high chemical activities.