Small Concentrations Research Articles

Contamination of consumer composts by metals, microplastics and other microscopic debris.

Very little information exists on the particle and chemical contamination of consumer (horticultural) composts. In this study, anthropogenic microcellulosics (AMCs), microplastics (MPs) and other microscopic debris, along with anthropogenically impacted metals (Cu, Zn, Pb), have been determined in 12 composts (seven garden composts and five growbags) purchased at outlets in the UK. AMCs and MPs, determined microscopically, were present in all samples at up to about 1100kg-1 dw. AMCs were more abundant and were dominated by fibres constructed of rayon and cotton, while petroleum-based MPs exhibited a greater diversity in shape and polymeric construction (including polyolefins, polyethylene terephthalate, polyvinyl chloride, resins, paints and rubbers). Other microdebris, present in much smaller concentrations in the composts, consisted of fragments of glass, metal and machined wood and spherical glass beads. Concentrations of the anthropogenically impacted metals, Cu, Pb and Zn, determined directly by energy-dispersive X-ray fluorescence spectrometry, were heterogeneously distributed and averaged 52.4, 192 and 51.6mgkg-1 dw, respectively. Although concentrations of anthropogenic particles were not related to cost or type of compost, physico-chemical properties or metal concentrations, a significant relationship between Pb content and particle diversity (number of polymers and debris types) was established. This relationship might result from the general contamination of the environment by both Pb and anthropogenic particulates, or the association of the metal with various types of material (e.g. paints, polyvinyl chloride, glass). Despite the ubiquity and diversity of MPs and microdebris in consumer composts, an understanding of their impacts on plant growth, either directly or indirectly (e.g. by interacting with metals), is unknown.

Testing the Effectiveness of Mangosized Skin Extract (Garcinia mangostana) as an Antimicrobial Against Bacteria Causing GI Tract Infections

The mangosteen fruit, which in Latin is called Garcinia mangostana Linn, is a plant whose entire parts can be used, including the skin of the fruit. Mangosteen fruit has bioactive compounds such as xanthones, especially α, β, and γ-mangostin where the level of antimicrobial action of α-mangosteen has been explored by many researchers and it has been observed that it is not only effective against bacteria but also against other microbes such as fungi and mycobacteria. Gastrointestinal system infections are a serious health problem and have not been completely resolved until now because cases are increasing every year. Gastrointestinal tract infections are a health problem in the world, including in Indonesia. Some infectious diseases of the gastrointestinal system that are often found in the wider community are typhoid fever, paratyphoid fever, diarrhea, and gastroenteritis. The bacteria that cause typhoid fever and paratyphoid fever are caused by the bacteria Salmonella Typhi & Salmonella Paratyphi. While diarrhea and gastroenteritis are caused by food poisoning and drinks contaminated by E. coli. This research is an experimental laboratory research using the disc diffusion/Kirby Bauer method by measuring the diameter of the clear zone which is a sign that there is an obstacle to the growth of Salmonella typhi and E. Coli bacteria by the antimicrobial compounds contained in the mangosteen fruit extract. The calculation results of this research showed that mangosteen peel extract (Garciana Mangostana L) against E. Coli bacteria with the antibiotic Chloramphenicol as control showed an average diameter of the inhibition zone of 30.5 mm, whereas Salmonella bacteria were not found or no inhibition zone was formed at the smallest concentration up to greatest concentration Keywords: Mangosteen Peel, garcinia mangostana l., Gastrointestinal Infections, Effectiveness of

Improving the behavior of thermoplastic starch with the addition of gum Arabic: Antibacterial, mechanical properties and biodegradability

The incorporation of different amounts of Gum Arabic (GA) in thermoplastic starch (TPS) obtained by extrusion and subsequent thermocompression has been studied. The sheets have been characterized by means of XRD, FTIR, TGA, moisture content, SEM, mechanical properties, antimicrobial activity and biodegradability via composting. The FTIR analysis of the sheets shows the presence of ester groups, while the TGA shows the presence of new processes and a residue much higher than expected is obtained. No changes in crystallinity are observed by XRD. The inclusion of GA confers antimicrobial properties to thermoplastic starch against the Gram + and Gram – bacteria studied even at the smaller concentrations. For a low GA content (0.5 and 1 g GA/100 g TPS) a homogeneous material is observed by SEM, as well as an important increase in tensile strength, modulus and deformation at break, which are very interesting properties facing the applicability of this material in single use plastics which are in contact with food or other consumable goods. At higher contents of GA, hollows and cracks appear in the material, compromising the mechanical properties. In all cases, the inclusion of GA delays the biodegradation process in soil, which can be related to its antibacterial capacity and especially in case of GA concentrations of 2 and 5 g/100 g of TPS with lower humidity of these TPS sheets.

Effects of Impact Energy and Aspect Ratio on the Motion of Particle Clouds in Stagnant Water

Abstract A series of laboratory experiments was conducted to investigate the effects of impact energy and other initial controlling parameters on the motion of particle clouds in stagnant water. Experiments were performed for two median sand diameters of D50 = 0.52 mm and 0.74 mm and nozzle diameters of do = 6 mm and 8 mm. Sand masses were converted to an equivalent pipe length with the same diameter as the nozzle, Lo, and a wide range of aspect ratios, Lo/do, between 2 and 93 was tested. The impact energy of sand particles was controlled by the release height of sand particles, and it was quantified by the non-dimensional release height, η, ranging from 1 to 21.5. It was found that particle clouds with higher impact energy had smaller concentration and velocity decay rates. This indicated that by increasing the release height, the momentum transfer between sand particles and the ambient water decreases. The time-series of instantaneous sand velocity were used to determine velocity fluctuations and turbulence intensity of sand particles and a direct correlation was found between sand velocity fluctuations and aspect ratio in particle clouds. The effects of impact energy on the anatomy of the resulted particle clouds were examined in this study. It was found that the cloud width increased dramatically when the impact energy of sand particles with high aspect ratios (i.e., Lo/do > 39) increased. Furthermore, the dispersion of sand particle began earlier as the kinetic energy of sand particles increased at the water surface.

Assessment of Syngas Storage Tank Hazards Taking Account of the Domino Effect

In most countries energy needs are satisfied using fossil fuels. Fossil fuel combustion involves environmental pollution and greenhouse gas emissions. The effect of the depletion of natural resources and the growing awareness of the need to protect the environment are the reasons that clean energy and alternative energy sources have been significant research issues. One of the most important technologies enabling efficient generation of low-emission energy is the gasification process of synthesis gas production. Syngas is primarily composed of hydrogen and carbon monoxide, but depending on the feedstock, it can also contain smaller concentrations, e.g., of carbon dioxide, methane and nitrogen. Because synthesis gas contains flammable and toxic substances, it may pose hazards to humans and the environment at every stage of gas production, storage, transport or final utilization if released uncontrollably. This paper presents the results of analyses related to hazards created by an uncontrollable release of synthesis gas during storage. A failure of a syngas system may cause damage to other, subsequent technological systems and facilities located in the neighborhood and containing dangerous substances. The problem gains special significance if syngas is stored in many tanks, where a failure of one may result in damage to subsequent tanks due to the so-called domino effect. The conditions in which the domino effect may occur are analyzed and the effect occurrence probability is determined depending on the mutual location of the tanks.

Sediment metals content in upstream Citarum river, West Java Province, Indonesia

Study of metal content in sediments is important for monitoring condition of Citarum river. This study aims to determine several metal namely Fe, Cu, Mn, Zn, Ni, Cr, Cd, Pb, Hg, and As in upstream Citarum river sediments. Research was conducted in the Cirasea sub-watershed, namely Gunung Wayang, Babakan Village, Cikitu Village, Wangi Sagara, Puncak Cae, Koyod, Andir, and Nanjung. Sediment samples were taken once a month from September to November 2022. Several physico-chemical parameter were carried insitu and laboratory. Sediment metal analysis was carried out using the ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometry) technique. Metal concentrations were compared with standards and the relationship between metal parameters and physico-chemical parameters was analyzed by PCA (Principal Component Analysis). Metals that were not found in all stations were Hg and Cd. The metal found with the largest concentration was Fe, otherwise metal found with the smallest concentration was As. Based on PCA, there are three groups based on metals and physico-chemical parameters. Advanced metal analysis needs to be carried out in the Citarum river from upstream to downstream to determine water quality of Citarum river.

Abstract 5411: Effect of different fatty acids on ccRCC behavior and metabolism

Abstract Introduction: Clear Cell Renal Cell Carcinoma (ccRCC) is the most common type of kidney cancer, presenting with defining characteristics of increased lipid droplets formation, loss of the VHL tumor suppressor, and low levels of fatty acid oxidation (FAO). Obesity is associated with an increase in ccRCC incidence, although obese patients respond better to different therapies, a phenomenon called as obesity paradox. The consumption of diets rich in lipids and leading to obesity has been increasing, but how the dietary composition affects ccRCC progression, or could be modulated in combination with other therapies for better responses is still unclear. In the present study, we aimed to evaluate how different fatty acids (FAs) affect ccRCC behavior and metabolism. Methods: We used 786-O and 769-P ccRCC cell lines. Palmitic acid (PA), oleic acid (OA), and linoleic acid (LA), which are saturated, monounsaturated, and polyunsaturated fatty acids, respectively were used as stimuli for the cells at 50 or 200µM. All stimuli were diluted in culture media with 5% FBS. Lipid droplets were evaluated by Oil Red O staining; viability was assessed by MTT; protein expression was tested by Western Blotting; Oxygen Consumption rate (OCR) by Seahorse; survival was quantified by clonogenic assay; and mRNA was measured by RT-qPCR. Results: All FAs increased the amount of lipid droplets compared to the control, but OA was the most potent. PA impaired the growth rate for cells compared to control, and other FAs in both cell lines, and did not increase the expression of cleaved caspase-3. PA, even in a lower concentration [50µM], impaired the formation of colonies for both cell lines compared to control and other FAs. LA impaired colony formation only in the higher concentration [200µM], while OA only induced a difference for 769-P cells at the smaller concentration, increasing the number of colonies. OA, and mainly PA, decreased 769-P cells migration, at the time of 6 and 12 h, while only PA decreased migration for 786-O cells, at the time of 12 h. LA, and mainly PA, increased CPT1a mRNA levels in 786-O cells but did not induce a significant difference to 769-P, and all FAs decreased FASN in both cell lines. Conclusion: It was demonstrated that OA was a potent inducer of lipid droplet formation, which can be protective in avoiding lipid peroxidation. On the other hand, PA and LA induced fewer lipid droplets probably because they are going to FAO, as we observed increased mRNA CPT1a levels, which is the rate-limiting enzyme in FAO. PA impaired potentially the formation of colonies and growth rate, and it is important to highlight that it was without inducing caspase 3-dependent programmed cell death. Taken together our data suggest that PA could be a target therapy for ccRCC, but it is still necessary for more studies in vitro and in vivo to evaluate how PA and enriched lipid diet can impact a better outcome for patients. Citation Format: Isadora Ramos de Andrade, Dazhi Wang, Scott Welford. Effect of different fatty acids on ccRCC behavior and metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5411.

Can Short-Term Online-Monitoring Improve the Current WFD Water Quality Assessment Regime? Systematic Resampling of High-Resolution Data from Four Saxon Catchments

The European Union Water Framework Directive (2000/60/EC; WFD) aims to achieve a good ecological and chemical status of all bodies of surface water by 2027. The development of integrated guidance on surface water chemical monitoring (e.g., WFD Guidance Document No. 7/19) has been transferred into national German law (Ordinance for the Protection of Surface Waters, OGewV). For the majority of compounds, this act requires monthly sampling to assess the chemical quality status of a body of surface water. To evaluate the representativeness of the sampling strategy under the OGewV, high-frequency online monitoring data are investigated under different sampling scenarios and compared with current, monthly grab sampling data. About 23 million data points were analyzed for this study. Three chemical parameters (dissolved oxygen, nitrate-nitrogen, and chloride concentration) and discharge data were selected from four catchments of different sizes, ranging from 51,391 km2 to 84 km2 (Elbe, Vereinigte Mulde, Neiße and two stations at Lockwitzbach). In this paper, we propose short-term online-monitoring (STOM) as a sampling alternative. STOM considers the placement of online sensors over a limited duration and return interval. In general, we: (I) compare the results of conventional grab sampling with STOM, (II) investigate the different performance of STOM and grab sampling using discharge data as a proxy for analyzing event-mobilized pollutants, and (III) investigate the related uncertainties and costs of both sampling methods. Results show that STOM outperforms grab sampling for parameters where minimum/maximum concentrations are required by law, as the probability of catching a single extreme value is higher with STOM. Furthermore, parameters showing a pronounced diurnal pattern, such as dissolved oxygen, are also captured considerably better. The performance of STOM showed no substantial improvements for parameters with small concentration variability, such as nitrogen-nitrate or chloride. The analysis of discharge events as a proxy parameter for event-mobilized pollutants proves that the probability of capturing samples during events is significantly increased by STOM.

Predicted Separation of Acid Gases from Gas Mixtures by Functionalized Porous Aromatic Frameworks.

The selective adsorption of target acid gas molecules from binary gas mixtures by porous aromatic frameworks (PAFs) with two identical functional groups per aromatic ring (PAF-R2) was computationally investigated using grand canonical Monte Carlo simulations. PAF-R2 adsorption was considered for three binary mixtures of small molecular concentrations of acid gas and abundant nitrogen gas (CO2/N2, SO2/N2, and H2S/N2). The results indicate that additional functional groups enhance acid gas loadings and selectivity, compared with pristine PAF and single-functionalized PAFs. Low pressures yield linearly increasing gas loadings and constant selectivity, while high pressures yield much higher adsorption and selectivity. In particular, SO2 loading and selectivity under high pressures are heavily influenced by the PAF's maximum adsorption limit, which can be linked back to the functional groups and their configuration. In summary, PAF-(3,5)-(COOH)2 (nomenclature of PAFs is provided in the Appendix in the Supporting Information) and many other PAF with the same two electron-withdrawing groups are predicted to have great acid gas adsorption and selectivity from gas mixtures, while PAF-(3,5)-(OH)2 (one of PAFs with two identical electron-donating groups) is predicted to have good adsorption and selectivity, especially under elevated pressures. The results of this work can provide insights into various types of PAFs with great selective adsorption ability and their corresponding conditions. The simulation procedures and results may inspire the exploration and screening of other types of PAFs or porous materials, for acid gas absorption.

The role of thermodiffusion in transpiration.

Plant leaf temperatures can differ from ambient air temperatures. A temperature gradient in a gas mixture gives rise to a phenomenon known as thermodiffusion, which operates in addition to ordinary diffusion. Whilst transpiration is generally understood to be driven solely by the ordinary diffusion of water vapour along a concentration gradient, we consider the implications of thermodiffusion for transpiration. We develop a new modelling framework that introduces the effects of thermodiffusion on the transpiration rate, E. By applying this framework, we quantify the proportion of E attributable to thermodiffusion for a set of physiological and environmental conditions, varied over a wide range. Thermodiffusion is found to be most significant (in some cases > 30% of E) when a leaf-to-air temperature difference coincides with a relatively small water vapour concentration difference across the boundary layer; a boundary layer conductance that is large as compared to the stomatal conductance; or a relatively low transpiration rate. Thermodiffusion also alters the conditions required for the onset of reverse transpiration, and the rate at which this water vapour uptake occurs.

Theoretical and experimental research on the performance of a refrigerant generating bubble pump with a high-accuracy semi-empirical model

Refrigerant generating bubble pump (RGBP) is the main component of diffusion absorption heat transformer (diffusion AHT), which is of great significance for waste heat recovery and lack of theoretical and experimental investigations. In present work, a high-accuracy semi-empirical model with H2O-CaCl2-R134a of good thermal stability has been firstly proposed by introducing generation and friction coefficients, which correlated geometry and operational parameters. The performance of RGBP with five independent operational parameters was calculated by the model. Moreover, experiments with five independent operational parameters were conducted by a closed setup, to validate the availability of the semi-empirical model. In the theoretical and experimental analyses, the refrigerant flow rate was used to evaluate generating performance, while the solution flow rate and pumping ratio were used to evaluate pumping performance. The results were concluded that: (1) the mean relative errors of refrigerant and solution flow rates between experimental and theoretical results were rapidly reduced from 103.34 % and 340.66 % to 18.29 % and 5.46 % by using the semi-empirical model; (2) higher generating temperature, larger diffusion gas flow rate, smaller concentration and lower system pressure promoted refrigerant generation; (3) higher motive head and smaller diffusion gas flow rate led to the increase of the solution flow rate and pumping ratio. The investigations may partially reveal the operation mechanism of RGBP, and the semi-empirical model is useful to predict performance of RGBP and choose suitable conditions of RGBP for the diffusion AHT with better performance.

Functionally graded structure of a nitride-strengthened Mg2Si-based hybrid composite

The ex-situ incorporation of the secondary SiC reinforcement, along with the in-situ incorporation of the tertiary and quaternary Mg3N2 and Si3N4 phases, in the primary matrix of Mg2Si is employed in order to provide ultimate wear resistance based on the laser-irradiation-induced inclusion of N2 gas during laser powder bed fusion. This is substantialized based on both the thermal diffusion- and chemical reaction-based metallurgy of the Mg2Si–SiC/nitride hybrid composite. This study also proposes a functional platform for systematically modulating a functionally graded structure and modeling build-direction-dependent architectonics during additive manufacturing. This strategy enables the development of a compositional gradient from the center to the edge of each melt pool of the Mg2Si–SiC/nitride hybrid composite. Consequently, the coefficient of friction of the hybrid composite exhibits a 309.3% decrease to –1.67 compared to –0.54 for the conventional nonreinforced Mg2Si structure, while the tensile strength exhibits a 171.3% increase to 831.5 MPa compared to 485.3 MPa for the conventional structure. This outstanding mechanical behavior is due to the (1) the complementary and synergistic reinforcement effects of the SiC and nitride compounds, each of which possesses an intrinsically high hardness, and (2) the strong adhesion of these compounds to the Mg2Si matrix despite their small sizes and low concentrations.

Detailed investigation of the structural and electrical properties of ZnO/Fe3O4 nanocomposites

The nanocomposites with the formula (1-x)ZnO+xFe3O4 (x = 0, 0.01, 0.03, 0.05, 0.7 and 0.09) were prepared using the sonomechanical method, while the pristine ZnO and Fe3O4 were prepared using the co-precipitation technique. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and a high-resolution broadband impedance analyzer were used to examine the structural, microstructure, and dielectric properties of the investigated samples. XRD analysis assures the wurtzite hexagonal structure of ZnO for all nanocomposite samples. The FTIR showed the existence of a functional group of ZnO and Fe3O4. The ac conductivity, dielectric constant (ε′), dielectric loss (ε′), electric modulus, impedance, and Nyquist plot were studied as a function of frequency and at different temperatures. The results show that the small concentration of Fe3O4 affects the ac conductivity and dielectric properties. The Koops phenomenological theory and the Maxwell-Wagner interfacial model were used to analyze the observed dielectric dispersion. The analysis of modulus and impedance results indicated the existence of non-Debye relaxation and the involvement of both grains and grain borders in polarization. The impedance study reveals that just one semicircle is observed in all samples, indicating that the influence of grain boundaries is more significant than the contribution of grains.

Resveratrol can Reduce the Aggressiveness of Hypoxic Colon Cancer Cells

Colorectal cancer is a significant global health problem characterized by the development of metastasis due to fast cell growth, tolerance to low oxygen levels, and the formation of new blood vessels. Notable advancements have been seen in the management of these instances; however, uncertainties persist about drug resistance and its accompanying adverse effects. Resveratrol, a natural polyphenol derived from several plants, has diverse pharmacological characteristics. The anticancer impact of this has piqued the curiosity of several researchers. The objective of our research was to investigate the impact of resveratrol on the proliferation, migration, and expression of angiogenic factors in hypoxic colorectal cancer cells by the use of resveratrol. Hypoxia was chemically induced using cobalt chloride. Serially diluted concentrations of resveratrol (200, 100, 50, 25, 12.5, and 6.25 \(\mu\)g/ml) were employed to assess the cytotoxic effect through the MTT assay. Smaller concentrations (below IC50) were utilized to investigate the impact of resveratrol on the migration of SW480 cells using the wound healing assay (50 \(\mu\)g/ml). The impact of resveratrol on the expression of vascular endothelial growth factor (VEGF) was assessed using the enzyme-linked immunosorbent assay (ELISA). The findings shown that resveratrol has the ability to effectively decrease cell proliferation in a dose-dependent way, inhibit cell migration and angiogenesis, via suppression of VEGF and HIF-1\(\alpha\). The significance of this etude lies in the enduring inability to effectively manage metastatic colorectal cancer. Suggesting that resveratrol might function as an adjunctive therapy and a useful supplement for those suffering from very metastatic colorectal cancer. The specific method by which resveratrol works is yet unknown, hence more study is needed to conduct experiments in living organisms and clinical trials.

The effect of UVA light/8-methoxypsoralen exposure used in Extracorporeal Photopheresis treatment on platelets and extracellular vesicles.

Extracorporeal Photopheresis (ECP) is a leukapheresis based treatment for Cutaneous T-Cell Lymphoma, which takes advantage of the cellular lethal effects of UVA light in combination with a photoactivated drug, 8-methoxypsoralen. 25% of patients treated with ECP do not respond to treatment, however the underlying mechanisms for this lack of response remain unknown. Platelets, a rich source of extracellular vesicles (EVs) and key mediators in thromboinflammatory oncological progression, as well as leukocytes, are both processed through ECP and are subsequently transfused back into the patient, delivering potent immunomodulation. The effect of exposing platelets and their EVs directly to Ultra Violet A light (UVA)/8-methoxypsoralen is currently unknown. Platelet-rich plasma (PRP) was isolated from healthy donors and exposed to UVA light and/or 8-methoxysporalen in vitro and platelet activation and aggregation was assessed. EV size and concentration were also characterised by Nanoparticle Tracking Analysis and Flow Cytometry. We found that UVA light and 8-methoxypsoralen treatment in vitro does not induce platelet aggregation or significantly alter levels of the platelet activation markers, soluble P-selectin or platelet factor 4, with circulating levels of small and large EV size and concentration remaining constant. Therefore, utilising the combination of UVA light and 8-methoxypsoralen used in ECP in vitro does not activate platelets or alter important circulating EVs. Further studies will be needed to validate if our observations are consistent in vivo.

Characterization of harmful gases and bioaerosols of pig farms: a review of the existing literature

From the ecological and economic point of view, intensive pig farming is drawing more and more attention due to the appearance of harmful substances, which significantly increases the risks of air, water and soil pollution. In addition, the optimal criteria for the content of harmful gases, dust and microorganisms in the environment of pig farms are currently not clearly defined. In order to better understand the interaction of harmful emissions and aerosols, the article reviews data from the literature on their main components, concentrations, and interactions. The results showed that the main pollutants in pig farming are harmful gases (ammonia (NH3), carbon dioxide (CO2), methane (CH4), nitrogen oxide (N2O), hydrogen sulfide (H2S), which are released from manure. The presence of even small concentrations of harmful gases in farm air can cause respiratory and cardiovascular system disorders not only in animals, but also in humans. Along with harmful gases, it is important to control the emission of solid particles and dust from livestock premises, which can form aerosols. Microbial aerosols in pig houses contain bacteria, fungi, viruses, which mainly come from the animals themselves, manure or service personnel. The bioaerosol includes the Firmicutes and Bacteroidetes bacterial divisions and their derivatives. In addition, the content of potentially dangerous bacteria in the bioaerosol can reach up to 40 %. A major concern causes the presence of a large number of antibiotic-resistant microorganisms in the air of these farms (including MRSA). The existing strategies and methods to combat these problems are still imperfect and need to be refined. Currently, the interaction of harmful gases, dust, solid particles and microorganisms is not taken into account, which can increase the toxic effect of each other on the animal's body. Therefore, there is a need for a better understanding of these interactions in order to improve the strategy for improving the microclimate conditions by correcting the microbiota, finding and developing biological preparations that contain natural bacteria capable of neutralizing odors and disinfecting livestock premises.

Mixing I and Br in Inorganic Perovskites: Atomistic Insights from Reactive Molecular Dynamics Simulations.

All-inorganic halide perovskites have received a great deal of attention as attractive alternatives to overcome the stability issues of hybrid halide perovskites that are commonly associated with organic cations. To find a compromise between the optoelectronic properties of CsPbI3 and CsPbBr3, perovskites with CsPb(BrxI1-x)3 mixed compositions are commonly used. An additional benefit is that without sacrificing the optoelectronic properties for applications such as solar cells or light-emitting diodes, small amounts of Br in CsPbI3 can prevent the inorganic perovskite from degrading to a photo-inactive non-perovskite yellow phase. Despite indications that strain in the perovskite lattice plays a role in the stabilization of the material, a full understanding of such strain is lacking. Here, we develop a reactive force field (ReaxFF) for perovskites starting from our previous work for CsPbI3, and we extend this force field to CsPbBr3 and mixed CsPb(BrxI1-x)3 compounds. This force field is used in large-scale molecular dynamics simulations to study perovskite phase transitions and the internal ion dynamics associated with the phase transitions. We find that an increase of the Br content lowers the temperature at which the perovskite reaches a cubic structure. Specifically, by substituting Br for I, the smaller ionic radius of Br induces a strain in the lattice that changes the internal dynamics of the octahedra. Importantly, this effect propagates through the perovskite lattice ranging up to distances of 2 nm, explaining why small concentrations of Br in CsPb(BrxI1-x)3 (x ≤ 1/4) have a significant impact on the phase stability of mixed halide perovskites.

The Effect of Intracrystalline Water on the Mechanical Properties of Olivine at Room Temperature

AbstractThe effect of small concentrations of intracrystalline water on the strength of olivine is significant at asthenospheric temperatures but is poorly constrained at lower temperatures applicable to the shallow lithosphere. We examined the effect of water on the yield stress of olivine during low‐temperature plasticity using room‐temperature Berkovich nanoindentation. The presence of water in olivine (1,600 ppm H/Si) does not affect hardness or yield stress relative to dry olivine (≤40 ppm H/Si) outside of uncertainty but may slightly reduce Young’s modulus. Differences between water‐bearing and dry crystals in similar orientations were minor compared to differences between dry crystals in different orientations. These observations suggest water content does not affect the strength of olivine at low homologous temperatures. Thus, intracrystalline water does not play a role in olivine deformation at these temperatures, implying that water does not lead to weakening in the coldest portions of the mantle.

Viscous flow and structural properties in water-ethanol-urea systems

The structural features of water-ethanol, water-urea and water-ethanol-urea systems were studied on the basis of experimental estimates of kinematic viscosity at different temperatures and concentra-tions. For this purpose, the concentration dependences of the Gibbs energy of activation of the viscous flow, the enthalpy of activation of the viscous flow and the entropy of activation of the viscous flow of the studied systems were analyzed. The results show that ethanol has a structuring and then de-structive effect on water up to a concentration of 0.15 molar, and urea has a destructive effect on the structure of water, starting from such small concentrations. The addition of urea to the ethanol-water system does not affect the inversion point.

High-resilience conductive PVA+AgNW/PDMS nanocomposite via directional freeze-drying

In this study, a polymer/metal nanowire nanocomposite employing a hard-core-soft-matrix design is developed, demonstrating high strength, recoverability, and electrical conductivity. Incorporation of conductive fillers in PDMS has been of interest, and here a new design in the form of nanocomposite consisting of polyvinyl alcohol/silver nanowire 3D porous composite that is then infiltrated with soft PDMS matrix is demonstrated. The vertically aligned freeze-dried structure within the composite exhibited a remarkable strength increase of up to 3.5 times compared to PDMS alone. The incorporation of hard and soft phases with 3D interfaces effectively hindered fracture propagation within the composite thereby greatly enhancing the stretchability; PVA+AgNW/PDMS nanocomposite demonstrated an excellent recoverability 82.7%. In addition, the silver nanowire network provides sufficient conductivity with small filler concentration of 0.47 vol% that makes PVA+AgNW/PDMS nanocomposite a compelling choice for flexible electronics application requiring a combination of electrical conductivity, high strength, and excellent recoverability.