Homogeneous Composition Research Articles

Low-temperature synthesis of porous high-entropy (CoCrFeMnNi)3O4 spheres and their application to the reverse water-gas shift reaction as catalysts.

A high-entropy porous spinel oxide [(Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4] was synthesized via a solvothermal method and calcination. Solvothermal conditions yielding homogeneous precursor composites with five metals were optimized. Low-temperature calcination of the amorphous composites at 500 °C for 60 min yielded porous spheres formed by small primary particles, with crystal structures attributed to single-phase spinels. The homogeneity of the five elements in the spheres was verified via scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy analysis. The high-entropy (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4 spheres exhibited superior catalytic activity and long-term stability for the reverse water-gas shift reaction at 700 °C for at least 15 h. The importance of the Cr component in stabilizing the spinel structure was demonstrated. Mn, Fe, Co, and Ni served as active sites in the reaction. The advantage of solvothermal synthesis for porous high-entropy materials was discussed.

The effect of silica nanoparticles obtained from different sources on mechanical properties of polyurethane nanocomposites

Spherical silica particles were synthesized from two different sources, tetraethyl orthosilicate (TEOS) and sodium sili-cate obtained from wheat straw ash, respectively. In the first case, monodispersed and microporous silica particles with average particle size of 400 nm were prepared by hydrolysis and condensation of TEOS. In the second case, the silica particles were generated from supersaturated sodium silicate solution. The extraction of silicate solution from wheat straw ash (WSA) was performed by the multi-step sequential extraction using 2,5 mol/L NaOH. WSA silica particles were polydispersed and contain the primary silica particles with average size of ~250 nm and agglomerates obtained by aggregation of primary silica particles, with average size of ~1.5 mm and 5 mm. The silica particles obtained from WSA have the average pore size of 28.3 nm, total pore volume of 0.1638 cm 3 /g and average surface area of 23.131 m 2 /g. Flexible polyurethane/silica composites with my(TEOS silica and WSA silica) and different filler concentration were synthesized. Dispersion of silica fillers in polyol system preceded the mixing with isocyanate resulted in formation of cavities in polyurethane-silica composite. On the other hand, dispersion of TEOS silica filler into isocyanate which preceded the mixing with polyol system resulted in homogenous and compact composite. The application of silica filler obtained from TEOS at filler concentration of 4 wt.% increased Young's modulus for 20% relative to that of polyurethane without filler. On the other side, the application of WSA silica filler resulted in reduced Young' s modulus probably due to large silica aggregates.

Structure characterization and cryoprotective activity of an exopolysaccharide from Pseudoalteromonas sp. LP6-12-2

Non-toxic natural antifreeze agents are urgently needed in many fields. Exopolysaccharides produced by psychrophilic bacteria from harsh habitats, such as Antarctica, to battle cold environments are a significant source of biological antifreeze agents. In this study, a homogeneous exopolysaccharide (EPS0-1) was extracted from Antarctica Pseudoalteromonas sp. LP6-12-2. Using High-performance gel permeation chromatography and High-efficiency anion chromatogram, respectively, the homogeneity, molecular weight, and monosaccharide composition of EPS0-1 were examined. EPS0-1 with a molecular weight (Mw) of 4351.31 kDa was an α-configuration polysaccharide containing uronic acid, amino and sulfuric acid groups, and composed of galactosamine hydrochloride, rhamnose, glucosamine hydrochloride, galactose, glucose, mannose, galacturonic acid, and glucuronic acid with rates of 1.40:9.40:4.90:32.0:37.2:6.50:4.10:4.40, respectively. Congo red test and I2-KI reaction found that the triple helix structure of EPS0-1 polysaccharide chain was weakly bound internally, with a longer side chain and/or more branches. The smooth and dense surface of EPS0-1 under Atomic force microscopy and Scanning electron microscopy revealed that it was large polysaccharide particles. Freeze-thaw cycle and freezing point determination experiment showed that EPS0-1 may significantly increase E. Coli's freezing resistance and decrease the solution's freezing point, respectively. EPS0-1 was capable of increasing the viscosity of the solution and displaying a high degree of thermal stability, which was proved by the rheological properties. And it was not hazardous to human normal liver cell line (LO2) in a specific concentration range. Therefore, the findings of this investigation established the basis for EPS0-1 as a potential antifreeze and food functional component.

Giant Pseudocyst of the Pancreas: A Rare Case Report

A Pancreatic Pseudocyst (PP) is a fluid-filled collection often found near the pancreas. It is characterised by its contained structure and homogeneous fluid composition, with little to no necrotic tissue. Individuals with a history of chronic pancreatitis, and to a lesser extent acute pancreatitis, may exhibit non specific symptoms. To minimise related morbidity and mortality, any potential complications must be identified. The authors present a case of a rare giant PP in a 28-year-old man who presented with abdominal pain and distention, severe backache, fever, frequent vomiting, loss of appetite, weight loss, and firm, sticky stools. Initially measuring 25×19.2×11.2 cm on a Computed Tomography (CT) scan, this PP was unusually large for its type. Due to the patient’s condition not being suitable, a direct cystojejunostomy was performed. Three drains were placed: an anastomotic drain near the anastomosis site, a Morrison’s drain in the Morrison pouch, and a pelvic drain. Later, a complication arose in the form of a faecal fistula, which was managed conservatively with a suction drain. The patient’s only primary complaint was non specific stomach pain, despite the size of the pseudocyst. Therefore, individuals with a history of chronic alcoholism and symptoms such as abdominal pain and distension should be evaluated for PP. A CT scan is recommended to investigate this condition, despite its rarity.

Self-adhesion of uncrosslinked poly(butadiene-co-acrylonitrile), i.e. nitrile rubber, an inhomogeneous and associative polymer.

Nitrile rubber (i.e., NBR) is a crosslinked copolymer of butadiene and acrylonitrile that finds widespread use in the automotive and aerospace industry as it sustains large, reversible deformations while resisting swelling by petrochemical fuels. We recently demonstrated that this material has a drift in composition due to the difference in reactivity between acrylonitrile and butadiene monomers during emulsion copolymerisation. Thus, although NBR is often thought of as a random copolymer, it does experience thermodynamic driving forces for self-assembly and kinetic barriers for processing like those of block copolymers.1 Here, we illustrate how such drift in composition hinders interdiffusion and prevents self-adhesion. The key result is that contacting uncrosslinked NBR (i) in the melt, (ii) in the presence of tackifiers, or (iii) in the presence of organic solvents promotes interdiffusion and enables self-adhesion. However, the contact times required for self-adhering, tc ∼ O(100 h), are orders of magnitude above those needed for non-polar synthetic rubbers like styrene-butadiene rubber (i.e., SBR) of comparable molecular weights and glass transition temperatures, tc ∼ O(100 s), unveiling the dramatic effect of compositional inhomogeneities and physical associations on polymer interdiffusion and large-strain mechanical properties. For example, when welded with organic solvents, the self-adhesion energy of NBR continues to increase after the solvent has evaporated because of polymer nanostructuring.

Influence of counterion type on the scattering of a semiflexible polyelectrolyte.

Understanding the influence of counterion and backbone solvation on the conformational and thermodynamic properties of polyelectrolytes in solution is one of the main open challenges in polyelectrolyte science. To address this problem, we study the scattering from semidilute solutions of a semiflexible polyelectrolyte, carboxymethyl cellulose (CMC) with alkaline and tetra-alkyl-ammonium (TAA) counterions in aqueous media using small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS), which allow us to probe concentration fluctuations of the polymer backbone and counterions. In SAXS, the calculated contrast arises primarily from the polymer backbone for both alkaline and TAA salts of CMC. In SANS, however, the contrast is dominated by the counterions for the TAA salts and the polymer backbone for the alkaline salts. Solutions are found to display a correlation peak in their scattering function, which at low concentrations is independent of counterion type. At moderate salt concentrations (c ≳ 0.1 M), the peak positions obtained from SANS and SAXS for the CMC salts with the TAA counterions differ. This divergence suggests a decoupling in the lengthscale over which the couterions and the polymer fluctuate. Upturns in the scattering intensity in the low-q region signal the presence of long-ranged compositional inhomogeneities in the solutions. The strength of these decreases with increasing counterion-solvent interaction strength, as measured by the viscosity B coefficient, and are strongest for the corresponding sodium salt of CMC.

Improving reconstructions in nanotomography for homogeneous materials via mathematical optimization.

Compressed sensing is an image reconstruction technique to achieve high-quality results from limited amount of data. In order to achieve this, it utilizes prior knowledge about the samples that shall be reconstructed. Focusing on image reconstruction in nanotomography, this work proposes enhancements by including additional problem-specific knowledge. In more detail, we propose further classes of algebraic inequalities that are added to the compressed sensing model. The first consists in a valid upper bound on the pixel brightness. It only exploits general information about the projections and is thus applicable to a broad range of reconstruction problems. The second class is applicable whenever the sample material is of roughly homogeneous composition. The model favors a constant density and penalizes deviations from it. The resulting mathematical optimization models are algorithmically tractable and can be solved to global optimality by state-of-the-art available implementations of interior point methods. In order to evaluate the novel models, obtained results are compared to existing image reconstruction methods, tested on simulated and experimental data sets. The experimental data comprise one 360° electron tomography tilt series of a macroporous zeolite particle and one absorption contrast nano X-ray computed tomography (nano-CT) data set of a copper microlattice structure. The enriched models are optimized quickly and show improved reconstruction quality, outperforming the existing models. Promisingly, our approach yields superior reconstruction results, particularly when only a small number of tilt angles is available.

Identical metamorphic record in distinct petrochemical systems: Case study of microscopically interlayered garnet amphibolite and metapelite from the Danba dome, SW China

It is known that different metamorphic rocks may have different abilities in recording metamorphic processes. Here, we report microscopically interlayered garnet amphibolite and metapelite layers in a rock from the Danba dome in eastern Tibetan Plateau, SW China. Both rock types exhibit similar garnet zoning patterns, biotite and plagioclase compositions, as well as peak P-T conditions (7.3–8.0 kbar / 700–725 °C for metapelite and 7.1–8.4 kbar / 690–710 °C for garnet amphibolite, respectively), indicating a global thermodynamic equilibrium state and the same metamorphic record of the two distinct layers. However, medium-sized garnet exhibits homogeneous core compositions and biotite preserves lower Ti and Fe# [= Fe2+ / (Fe2+ + Mg)] at the lithological interface, possibly indicating more intense chemical homogenization at the metamorphic peak and retrograde modification at the interface caused by the possible presence of vast fluid. Sensitive high-resolution ion microprobe (SHRIMP) UPb dating of metamorphic zircon show a wide dispersion of ages (c. 200–155 Ma), overlapping previous age data reported for this region. These results indicate that differences in petrochemical compositions may not lead to significant distortion in the metamorphic records, including garnet zoning patterns and peak P-T conditions. This further suggests that metamorphic rocks originating from diverse protoliths, which exhibit varying peak P-T conditions within the same locality, could either be a result of the tectonic juxtaposition of distinct tectonic slices or the influence of varying fluid conditions.

제주도 사계 해안사구식생의 군락분류를 통한 생태교육자료 개발

This study was conducted to classify communities based on vegetation types distributed in Sagye coastal sand dunes in Seogwipo city, Jeju Special Self-Governing Province, the southernmost part of Korea, and to develop related educational materials. The field vegetation survey was conducted for approximately 2 years, from April 2020 to October 2021 with the Z.-M method emphasizing plant sociological species composition and habitat homogeneity. Through the survey, we obtained 190 vegetation data and analyzed the behavioral patterns of a total of 141 plant taxa using 9 levels of converted integrated dominance and relative contribution (r-NCD). Vegetation types were broadly classified into three correlated categories: herb communities on dunes, shrub communities on dunes, and artificial afforestation vegetation. As a result of community classification, 19 units of vegetation were identified, comprising a total of 6 associations and 13 communities. The representative communities were the Vitex rotundifolia community, which is coastal dune shrub vegetation, and the Pinus thunbergii community, which is arboreal vegetation. In the evaluation of vegetation naturalness, the [Ⅱ] grade was high with 7 communities, accounting for 36.8% of the total community, and the [Ⅲ] grade was 9 communities, accounting for 47.46% of the total community. Vegetation naturalness grade [Ⅱ] areas are defined as vegetation that is selectively and strictly required for ecological conservation activities, so conservation measures for this vegetation are considered necessary. This research data is expected to be widely used by teachers in developing field ecological education materials, as well as ecological learning education materials, by providing ecological-based vegetation data by establishing a community classification and community system for existing vegetation.

Optical Approach for Mapping the Intercalation Capacity of Porous Electrodes.

The intercalation capacity of a porous electrode in real batteries is not uniform spatially due to the inevitable structural and compositional inhomogeneity and site-dependent ion and electron transport features. Reliable methods to quantify the capacity distribution are highly desirable but absent so far in battery research. In this paper, a novel optical technique, oblique incident reflection difference (OIRD), was employed to monitor in situ the electrochemical ion (de)intercalation behavior of Prussian blue analogue (PBA) porous films. The OIRD signal responded synchronously to the ion (de)intercalation, and the change in the OIRD signal (ΔI) was positively correlated with the local electrochemical capacity, thereby enabling mapping of the spatially resolved ion storage capacity of the films. Optical analysis further showed that the OIRD response originated from the ion (de)intercalation-induced dielectric constant change of PBA films. This work therefore offers an intriguing in situ and spatially resolved tool for the study of rechargeable batteries.

Spectroscopic properties, Judd Ofelt analysis of U and Eu activated Li2O-ZnO-SrO-B2O3-P2O5 borophosphate glasses for solid-state lighting applications

Uranium and europium doped borophosphate glasses with the base composition of (Li2O)(ZnO)0.5(SrO)0.4(B2O3)2.55(P2O5)0.5 were synthesized by melt -quenching. The X-ray diffraction profile affirmed that all the synthesized samples were devoid of crystallinity and amorphous in structure. The absence of precipitations/grains in the scanning electron micrographs further validated the amorphous character and compositional homogeneity of the prepared glass. The FTIR spectra revealed several prominent vibrational bands in 713–1568 cm−1 range and were assigned to the corresponding B-O-B and P-O-P and B-O-P bonding. The thermal characteristics of the synthesised glass samples were investigated using differential thermal analysis experiments. The broad photoluminescence (PL) spectra observed for the uranium doped glass with emission maxima at 523 nm resembles the hexavalent U(VI) emission in a disordered amorphous environment. The emission profile of the Eu doped glass displayed several characteristics peaks due to 5D0 → 7FJ transitions. The phonon energy of the base glass was found to be 1005 cm−1. The Judd-Ofelt analysis showed that for all the doped glass, the JO intensity parameter Ω4 was always greater than Ω2 indicating that Eu3+ ions are primarily arranged in a centrosymmetric environment in the studied host. Radiative properties of 5D0 → 7FJ=1-4 transitions of the Eu3+ such as branching ratios, emission cross-section, and transition probabilities were computed. Energy transfer pathways of UO22+ → Eu3+ in the codoped borophosphate glass were described. The CIE chromaticity and PL results suggest that the intense red emission of Eu doped glasses could be useful for phosphor applications.

Electrochemical Impact of Inhomogeneous Binder Distribution in Lithium-Ion Battery Electrodes

In recent years, the application possibilities of the lithium-ion battery (LIB) have increased significantly. Moreover, the demand for LIBs will rise in the next few years, especially in the automotive sector. This leads to an increasing importance of careful management of the limited lithium resources. Battery production offers high savings potential, as the current scrap rate is around 5-30% [1,2]. The scrap arises in the various process steps such as electrode production, battery conditioning or even from impure raw materials. Especially during the electrode production including mixing, coating, drying and calendaring, various defects can be implemented into the electrodes. Defects such as compositional inhomogeneities (e.g., inhomogeneous binder distribution), microstructural inhomogeneities (e.g., thickness variations), line defects, point defects or even foreign particle contamination can lead to increased scrap rates [3].For the detection of defects, there are already a few established methods such as computed thermography, camera-based optical systems, or post-mortem analyses. However, the detection of the defects might not be sufficient to evaluate the electrode usability since the influence might still be tolerable. Therefore, the impact of the defect type, size, and concentration and resulting determination of the tolerance limits is decisive for the reduction of production waste.In this work we focus on the influence of compositional inhomogeneities on the battery performance. Compositional inhomogeneities like inhomogeneous binder distribution can modify the local electrode characteristics e. g. porosity/tortuosity. This can lead to local higher or lower c-rate followed by faster or slower local degradation. In worst case these inhomogeneities can cause lithium plating or short circuits and shorten the lifetime of LIBs significantly.To determine the criticality and establish tolerance limits, we produced and analyzed defective and defect-free electrodes. For the determination of the impact of the inhomogeneities we developed a special experimental setup that allows us the analysis of the internal dynamics of the interaction between defect-containing (selective modification of the binder content) and defect-free (target binder content) electrodes. Therein, compensating currents continuously redistribute the inhomogeneous charges in electrodes with different binder content. This balancing effect was studied in terms of the caused accelerated aging.This experimental approach provides a foundation for further investigation and for deep understanding of the effect of electrode defects. This knowledge represents a basis for further developing of effective quality assurance strategies and reducing scrap rates accompanying by careful management of the limited lithium resources.[1] Gaines, L.; Dai, Q.; Vaughey, J. T.; Gillard, S.: Direct Recycling R&D at the ReCell Center. Recycling. 2021, 6 (2), 31. DOI: 10.3390/recycling6020031. [2] Brückner, L.; Frank, J.; Elwert, T.: Industrial Recycling of Lithium-Ion Batteries—A Critical Review of Metallurgical Process Routes. Metals 2020, 10 (8), 1107. DOI: 10.3390/met10081107. [3] du Baret de Limé, A.; Lein, T., Maletti, S.; Schmal, K.; Reuber, S.; Heubner, C. and Michaelis, A.: Impact of Electrode Defects on Battery Cell Performance: A Mini Review. Batteries & Supercaps 2022, 5, e202200239, doi.org/10.1002/batt.202200239.

Quantitative Determination of the Compositional Inhomogeneity in NMC Cathode Materials by Williamson-Hall Analysis

Over the past decades, the co-precipitation synthesis technique has been used, particularly for making LiNixMnyCozO2 (NMC) cathode materials for lithium-ion batteries (LIBs), due to better control of particle morphology and higher compositional homogeneity in the final NMC product compared to other methods. However, the co-precipitation method introduces complexity and consumes large amounts of energy and water, which can increase cost. This has led researchers to investigate solid-state NMC synthesis techniques in order to improve sustainability and reduce LIB cost [1-3]. Obtaining homogeneous mixing of transition metals at the atomic scale by solid-state methods remains a challenge. Since compositional homogeneity has a vital effect on the electrochemical performance of the NMCs, it is essential to quantitatively estimate the degree of inhomogeneity in cathode materials for the development of new synthesis methods.In the present study, a quantitative X-ray diffraction (XRD) analysis technique using the Williamson-Hall (WH) method is used to determine the degree of inhomogeneity in NMC precursors and NMC cathode materials. In this regard, single-phase rock salt (RS) precursors with varying degrees of transition metal homogeneity were prepared by combining NiO, MnO and CoO by grinding for different times, followed by heating under an Ar flow. Then, NMC cathode materials were made by heating the RS-precursors with lithium carbonate in air. EDS elemental maps showed that transition metal inhomogeneity existed in the RS-precursors and final NMCs and that this inhomogeneity is primarily associated with the Mn distribution (Figure 1(a)). Furthermore, the compositional inhomogeneity became reduced with increasing precursor grinding time.Using a WH analysis method, composition variation in the NMC precursor and in the final NMC product could be quantitatively determined from conventional XRD powder patterns. Utilizing this analysis, it was found that inhomogeneity in the precursor is translated into the final NMC, so that a similar trend in the degree of inhomogeneity was observed for both synthesized precursors and their NMC products (Figure 1(b) and (c)). Additionally, NMCs with high compositional homogeneity showed much better electrochemical performance compared to the samples with higher degree of inhomogeneity. We believe the proposed method is highly useful in the development of new cathode precursors and in predicting the performance of the NMC cathode materials by quantitatively determining their degree of compositional inhomogeneity.

Microstructure and magnetocaloric effect in nonequilibrium solidified Ni-Mn-Sn-Co alloy prepared by laser powder bed fusion

Additive manufacturing (AM) enables complex structures of Ni-Mn-X Heusler alloys to be utilized in solid state refrigeration systems. Here, the laser powder bed fusion (L-PBF) technique was used to fabricate a Ni-Mn-Sn-Co magnetic shape memory alloy with sophisticated geometries. Relative densities ranging from 96.12 to 97.04% were attained. L21–ordered austenite and an average structure of 5-layered modulated (5 M) martensite were observed at ambient temperature. The nonequilibrium solidification condition and repeated remelting processes during L-PBF gave rise to a strong 〈001〉A texture in austenite with epitaxial columnar grains along the build direction and dendrites related to microsegregation. Furthermore, the austenite exhibited nanodomains in its matrix and the martensite possessed stacking-mediated structures with 4–7 layers of atoms randomly stacked within the twin substructures. The combined influence of relatively homogeneous composition and specific microstructures yielded a competitive magnetization difference of 81.0 A·m2·kg–1 and a maximum magnetic entropy change of about 14 J·kg–1·K–1 with a working temperature interval of about 22 K under the external field change of 5.0 T without any heat treatment. The as-built state alloy is expected to facilitate the development of new laser AM techniques for Ni-Mn-X alloys.

(Keynote) Oxygen Reduction and Evolution Reactions on Faceted MnxCo1-XFe2O4 Nanoparticles Prepared By Induction-Coupled Plasma

Substantial research efforts are directed toward the development of precious metal-free catalysts for fuel cells, metal-air batteries and electrolyzers, because the deployment of these technologies requires the synthesis of low-cost catalysts with controlled properties in large quantities.Mixed spinel oxides are a promising class of catalytic materials for the oxygen evolution (OER) and oxygen reduction (ORR) reactions, and thus several works have been devoted to the understanding of the structure – composition – activity relationships. Examples include the correlation between activity of spinel oxides and the covalency of the bond formed between the oxygen species and the metal cation in the octahedral sites1, or the possible role of metal cations in the tetrahedral sites in the oxygen electrocatalysis2. However, studies highlighting the importance of the facet engineering on the electrocatalytic activity of spinel oxides3 are still rare.Here, we will present our recent work on facetted nanoparticles MnxCo1-xFe2O4 (0 ≤ x ≤ 1) prepared by thermal plasma induction; a one step4, cost-effective and scalable method allowing the synthesis of large amounts (up to 30 g h-1 for 50 kW units) of uniform and crystalline nanoparticles5.Structural characterization by X-ray diffraction and TEM-EELS analysis showed that the mixed ferrite nanoparticles are formed by individual nanocrystals with well-defined truncated octahedron shape and with {100} and {111} facets mainly exposed, have high crystallinity, a median particle size of 40 nm and a homogeneous composition down to the atomic level.Electrochemical studies conducted in 0.1M KOH using the rotating disk electrode showed the highest activity was found for carbon black + Mn0.5Co0.5Fe2O4 composite electrode: half-wave potential for oxygen reduction 140 mV more negative than that of 20 wt% Pt/C; 420 mV oxygen evolution overpotential at 10 mAcm-2 (identical to IrO2/C). These are among the best performances reported for ferrites considering the size of the nanocrystals.Computational studies using density functional theory used to study the adsorption of oxygen molecule on the {100} and {111} facets of both CoFe2O4 and Mn0.5Co0.5Fe2O4 demonstrated that the Mn0.5Co0.5Fe2O4 {111} surface appears to have a highest affinity for the O2 molecule. The sites with lowest adsorption energy on each surface were identified and further analysis of O-O bond length and frequency as well as the Mulliken charge and populations confirmed the activation of the adsorbed O2 molecule. The energy diagrams of the ORR and OER computed for both Mn0.5Co0.5Fe2O4 {100} and {111} surfaces also pointed for a higher electrocatalytic activity for the {111} facet.

Chemical, structural, microstructural, mechanical, and biological characterization of Ti–25Ta-xNb system alloys for biomedical applications

This study delves into the comprehensive characterization of the Ti–25Ta-xNb alloy system, whith a focus on its potential biomedical applications. Int intriguing insights into these alloys properties were unveiled through a systematic investigation encompassing EDS analysis, density measurements, chemical mapping, X-ray diffraction, microstructural examination, and microhardness assessments. The chemical composition results confirm that these alloys exhibit the appropriate stoichiometries, with the melting process yielding homogeneous compositions. Notably, the Ti–25Ta–10Nb and Ti–25Ta–20Nb alloys showcase the coexistence of α and β phases, while those with 30 % and 40 % Nb consist solely of the β phase, highlighting the β-stabilizing role of Nb and Ta. These results align seamlessly with X-ray diffractograms, Rietveld refinement data, and microstructural observations. The analysis further reveals a decrease in edges B and C of the α" structure, consistent with previous literature, indicating the alloys sensitivity to Nb additions. In terms of hardness, a discernible trend emerges with the stabilizing of the β phase, leading to reduced hardness values, as anticipated. Excitingly, not all alloys in the Ti–25Ta-xNb system exhibited cytotoxic effects, while they facilitated the crucial process of cell adhesion. This presents a promising prospect for their application in biomaterials. Among the developed alloys, the Ti–25Ta–30Nb alloy stands out due to its proximity to pure titanium in terms of hardness and its potential to promote cell proliferation.These findings underscore the potential of the Ti–25Ta-xNb alloy system for biomedical applications, provided that further studies optimize their suitability for such purposes.

Different VOC species derived from fugitive emissions at various altitudes around petrochemical plant

Volatile organic compounds (VOCs) emitted from fugitive sources are crucial for environmental and health risk assessments. However, monitoring these emissions at ground level, according to traditional technical specifications, has made it challenging to identify polluted air masses and collect purposeful samples. In this study, we focused on utilizing an unmanned aerial vehicle system to obtain air samples around a petrochemical industrial park. We conducted a quantitative analysis of 108 VOC species and compared the results between aerial and ground-level samples. The findings indicated a higher presence of reactive compounds in the aerial samples. The sample pairs exhibited relatively homogeneous compositions of hydrocarbons with fewer than eight carbon atoms, suggesting a well-mixed condition for light compounds. Conversely, the aerial samples exclusively exhibited high mixing ratios of C8–C15 compounds, including branched paraffins and aldehydes. Based on the quantified VOCs, we evaluated the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP). The results highlighted aldehydes, alkenes, and aromatics, particularly propanal, 2-butene, m/p-xylene, and benzaldehyde, as priority control compounds. Additionally, the semiquantitative concentrations of these non-quantitative C8–C15 species ranged from 1 to 15 ppbv, with a total content exceeding 150 ppbv, it indicated the significant contribution to ambient secondary pollution. These results provide valuable insights into the identification of potential emission sources and the assessment of environmental repercussions attributed to these intermediate-volatile organic compounds from fugitive emissions around petrochemical plant.

Electrical Resistance, Stability and Mechanical Properties of PVC Composites Containing Graphite and Semiconductor for Sensor Technologies

This study aimed to obtain a new flexible poly vinyl chloride (PVC) based composite with conductive or semiconductor properties. Additives were graphite and semiconductor zinc oxide (ZnO). A non-ionic surfactant was also firstly used to obtain a homogeneous composite. For the characterization of these new composites; humidification, electrostatic discharge (ESD), electrical resistance, thermal shock measurements, tensile test and morphological and microscopic (SEM) measurements were performed. For the light test, a “Solar simulator” with a 1000 W xenon lamp was used. The electrical resistance and tensile strength of the materials were measured at each test step. According to the data obtained, it was determined that the electrical resistance of the materials with high graphite content, without ZnO, is still stable, while the electrical resistance of the ZnO-doped materials decreases and their conductivity increases considerably in special stimuli such as light. P3G2Z (32% PVC, 60% Graphite, 8% ZnO) was greater than 3 MΩ, with a large change in conductivity after electrostatic discharge, reaching 1078.33 kΩ, with the largest difference observed. It was determined that the resistance of P2G3Z and P1G1Z composite materials under solar radiation decreased approximately 81 and 23 times, respectively. This event proves that the composites become light sensitive semiconductor. As a result, the electrical and mechanical data of flexible, sensitive, conductive and semiconductor new polymers by doping PVC with graphite and ZnO nanoparticles at different rates will make a great contribution to the sensor, actuator, management system control mechanisms, and the robots used in the automotive and defense industries.

Ocular surface microbiota in patients with varying degrees of dry eye severity.

To elucidate the profiles of commensal bacteria on the ocular surfaces of patients with varying severity of dry eye (DE). The single-center, prospective, case-control, observational study categorized all participants into three distinct groups: 1) control group (n=61), 2) mild DE group (n=56), and 3) moderate-to-severe DE group (n=82). Schirmer's tear secretion strips were used, and the bacterial microbiota was analyzed using 16S ribosomal ribonucleic acid gene sequencing. The three groups had significant differences in alpha diversity: the control group had the highest richness (Chao1, Faith's phylogenetic diversity), the mild DE group showed the highest diversity (Shannon, Simpson), and the moderate-to-severe DE group had the lowest of the above-mentioned indices. DE severity was positively correlated with a reduction in beta diversity of the microbial community, with the moderate-to-severe DE group exhibiting the lowest beta diversity. Linear discriminant analysis effect size presented distinct dominant taxa that significantly differed between each. Furthermore, the exacerbation of DE corresponded with the enrichment of certain pathogenic bacteria, as determined by random forest analysis. As DE severity worsens, microbial community diversity tends to decrease. DE development corresponds with changes in microbial constituents, primarily characterized by reduced microbial diversity and a more homogenous species composition.

The Porothermoelastic Stress Evolution of Inhomogeneous Solid due to Near-Surface Reservoir

Anisotropic and heterogeneous solids, comprising a minimum of two or more elements with different properties, appear pervasively in rock materials including the pore structure and mineral composition of quartz and granite and usually have extensive applications in construction aggregates, dimension stone, geotechnical engineering, and petrology/geology. The elastic stress fields of inhomogeneous materials or composites inevitably change due to the presence of heterogeneous microstructure under applied external conditions, and hence the total mechanical and physical properties are affected by the temperature and pore pressure fluctuations beneath the surface. In this paper, the thermoporoelastic (TPE) approach on the basis of eigenstrain concept is introduced to predict the stress fields in fluid-saturated porous geologic materials like hydrocarbon reservoirs or aquifers by accounting for the coupling between thermal, poroelastic, and mechanical effects. It is an extension of the micromechanical theory that also incorporates thermal effects like pore pressure changes and temperature alternations. In addition, the TPE approach provides an important multiphysical modeling tool for understanding subsurface fluid-rock interactions and stress states in applications like unconventional oil/gas and geothermal energy.