Emergent electric field control of phase transformation in oxide superlattices.

Electric fields can transform materials with respect to their structure and properties, enabling various applications ranging from batteries to spintronics. Recently electrolytic gating, which can generate large electric fields and voltage-driven ion transfer, has been identified as a powerful means to achieve electric-field-controlled phase transformations. The class of transition metal oxides provide many potential candidates that present a strong response under electrolytic gating. However, very few show a reversible structural transformation at room-temperature. Here, we report the realization of a digitally synthesized transition metal oxide that shows a reversible, electric-field-controlled transformation between distinct crystalline phases at room-temperature. In superlattices comprised of alternating one-unit-cell of SrIrO3 and La0.2Sr0.8MnO3, we find a reversible phase transformation with a 7% lattice change and dramatic modulation in chemical, electronic, magnetic and optical properties, mediated by the reversible transfer of oxygen and hydrogen ions. Strikingly, this phase transformation is absent in the constituent oxides, solid solutions and larger period superlattices. Our findings open up this class of materials for voltage-controlled functionality

An integrated systems approach to understanding distortion and residual stress during thermal processing: design for heat treating

Heat treatment processes are used to develop the desired mechanical properties for steels. Unfortunately, heat treatment, especially quenching, can cause distortion. Failure to meet geometry specifications can result in extensive rework or rejection of the parts. A series of quenching simulations, using DANTE, have been conducted on an AISI 4140 steel Navy C-ring distortion coupon and a WPI designed plate with a hole to determine the effects of quenching process parameters including part geometry, agitation during quenching, and quench start temperatures on distortion. The heat transfer coefficients (HTC) of the quenchant with selected pump speeds were measured by CHTE quench probe system, which is the key input for heat treatment simulation. The maximum HTC of the quenching oil was increased from 2350 W/m2K to 2666 W/m2K with higher pump speed. Quenching experiments were also conducted. It was found that the experimental measured gap opening of the standard Navy C-rings increased from 0.307mm without agitation to 0.536mm at a high agitation. Quench start temperature does not have a significant effect on the gap opening. The experimental results showed good agreement with simulation results. The important processing parameter identification was conducted using design of experiments (DoE) coupled with analysis of variance (ANOVA). The effect of processing parameters in decreasing order of importance were determined to be: quenchant type, part geometry, agitation speed, quenching orientation, quenchant temperature, immersion rates, and quench starts temperature. Based on the simulation and experimental results, it was found that the two most import parameters are: 1. The part geometry and size (product design) 2. The temperature dependent heat transfer coefficients between the part and the quenchant (process design) The coupling of these product and process parameters is necessary to apply the systems analysis that must be accomplished to understand the interaction between the part design and process design parameters. This coupling can be accomplished by locally applying the well-known Biot number. Bi (T) = h(T) * L / k(T) Where h(T) = film coefficient or convective heat transfer coefficient [W/m2*K]. LC = characteristic length, which is generally described as the volume of the body divided by the surface area of the body [m]. k(T) = thermal conductivity of the body [W/m*k] The concept of a local Biot number is introduced to quantify the local variations of part size, geometry and heat transfer coefficient. First, a large Bi indicates large temperature gradients within the part. Second, large local (geometry dependent) variations in Bi number will lead to large lateral temperature gradients. Therefore, variations in local Bi can lead to large temperature gradients and therefore high stress during quenching and finally distortion. This local Bi concept can be used in a systems approach to designing a part and the quenching system. This systems approach can be designated as design for heat treating.<br /

Dislocation loop bias and void swelling in irradiated α-iron from mesoscale and atomistic simulations

Abstract Dislocation loops are ubiquitous in irradiated materials, and dislocation loop bias plays a critical role in void swelling. However, due to complicated interactions between dislocation loops and point defects, it is challenging to evaluate the bias factors of dislocation loops. Here, we determine the bias of sessile loops in α-iron using a recently developed atomistic approach based on the lifetime of point defects. We establish a mechanistic understanding of the loop interaction based on the diffusion tendency of point defects near the loop core region. Mobile self-interstitial atoms tend to be absorbed from the edge of the loop, and a trapping region perpendicular to the habit plane of the loop exists. The dislocation loop bias is found to be substantially lower than those of straight dislocations in α-iron and should be included in swelling rate estimates. With the obtained sink strength and bias values, agreement is achieved with experimental results for both absolute values and temperature dependence

Structure evolution characterization of Anyang anthracites via H 2O2 oxidization and HF acidification

The structural characteristics of the raw coal (AY), the H2O2 oxidized coals (AY–H2O2) and the HF acidized AY–H2O2 (AY–H2O2–HF) were investigated by SEM, X-ray diffraction, Raman and FTIR spectroscopy. The results indicate that the derivative coals show an obvious increase in the aromaticity, crystalline carbon content and hydroxyl content, especially the AY–H2O2–HF. The stacking layer number of crystalline carbon decreases and the aspect ratio (La/Lc) remarkably increases for AY–H2O2 and AY–H2O2–HF. The crystalline layers become much thinner. The particle size of AY–H2O2–HF in width significantly decreases from 1 μm to less than 100 nm. The combination of H2O2 oxidization and HF acidification is effective to reduce the size of the aromatic layers and to increase the reactivity of derivative coals. The process can help us obtain the superfine crystalline carbon materials like graphite structure

Fine Mapping and Functional Analysis of Major Regulatory Genes of Soluble Solids Content in Wax Gourd (Benincasa hispida)

Soluble solids content (SSC) is an important quality trait of wax gourd, but reports about its regulatory genes are scarce. In this study, the SSC regulatory gene BhSSC2.1 in wax gourd was mined via quantitative trait locus (QTL) mapping based on high-density genetic mapping containing 12 linkage groups (LG) and bulked segregant analysis (BSA)-seq. QTL mapping and BSA-seq revealed for the first time that the SSC QTL (107.658&ndash;108.176 cM) of wax gourd was on Chr2 (LG2). The interpretable phenotypic variation rate and maximum LOD were 16.033% and 6.454, respectively. The QTL interval contained 13 genes. Real-time fluorescence quantitative expression analysis, functional annotation, and sequence analysis suggested that Bch02G016960, named BhSSC2.1, was a candidate regulatory gene of the SSC in wax gourd. Functional annotation of this gene showed that it codes for a NADP-dependent malic enzyme. According to BhSSC2.1 sequence variation, an InDel marker was developed for molecular marker-assisted breeding of wax gourd. This study will lay the foundation for future studies regarding breeding and understanding genetic mechanisms of wax gourd

Single‐Crystal Nanowire Cesium Tin Triiodide Perovskite Solar Cell

Abstract This work reports for the first time a highly efficient single‐crystal cesium tin triiodide (CsSnI 3 ) perovskite nanowire solar cell. With a perfect lattice structure, low carrier trap density (≈5 × 10 10 cm −3 ), long carrier lifetime (46.7 ns), and excellent carrier mobility (>600 cm 2 V −1 s −1 ), single‐crystal CsSnI 3 perovskite nanowires enable a very attractive feature for flexible perovskite photovoltaics to power active micro‐scale electronic devices. Using CsSnI 3 single‐crystal nanowire in conjunction with highly conductive wide bandgap semiconductors as front‐surface‐field layers, an unprecedented efficiency of 11.7% under AM 1.5G illumination is achieved. This work demonstrates the feasibility of all‐inorganic tin‐based perovskite solar cells via crystallinity and device‐structure improvement for the high‐performance, and thus paves the way for the energy supply to flexible wearable devices in the future

Aggravated pneumonia and diabetes in SARS-CoV-2 infected diabetic mice

ABSTRACTMultiple clinical and epidemiological studies have shown an interconnection between coronavirus disease 2019 (COVID-19) and diabetes, but experimental evidence is still lacking. Understanding the interplay between them is important because of the global health burden of COVID-19 and diabetes. We found that C57BL/6J mice were susceptible to the alpha strain of SARS-CoV-2. Moreover, diabetic C57BL/6J mice with leptin receptor gene deficiency (db/db mice) showed a higher viral load in the throat and lung and slower virus clearance in the throat after infection than C57BL/6J mice. Histological and multifactor analysis revealed more advanced pulmonary injury and serum inflammation in SARS-CoV-2 infected diabetic mice. Moreover, SARS-CoV-2 infected diabetic mice exhibited more severe insulin resistance and islet cell loss than uninfected diabetic mice. By RNA sequencing analysis, we found that diabetes may reduce the collagen level, suppress the immune response and aggravate inflammation in the lung after infection, which may account for the greater susceptibility of diabetic mice and their more severe lung damage after infection. In summary, we successfully established a SARS-CoV-2 infected diabetic mice model and demonstrated that diabetes and COVID-19 were risk factors for one another