Anisotropic effects of oxygen vacancy defects on the electrical properties of highly oriented bismuth titanate ferroelectric ceramics

Bismuth titanate (Bi₄Ti₃O₁₂, BIT) exhibits a high Curie temperature and anisotropic electrical performance owing to its layered perovskite structure, and hence, it is an important ferroelectric material for high-temperature piezoelectric applications. It is crucial to understand the effects of the anisotropy in BIT-based ferroelectrics for developing novel high-temperature piezoelectric materials. In this study, a highly textured BIT ceramic was fabricated using the tape-casting technique from highly grain-oriented BIT platelets prepared by the molten salt method. The textured BIT ceramic showed a dense microstructure and high grain orientation along the (00l) plane with a texturing degree F_00l = 0.86. It exhibited significant anisotropy in the electrical properties along the directions parallel and perpendicular to the axis of the tape-casting plane. Double ferroelectric hysteresis P–E loops and normal ferroelectric P–E loops were observed in the parallel and perpendicular samples, respectively. In addition to the layered crystal structure and domains, the anisotropy in the arrangement of the oxygen vacancy defects and their transport in the structure led to a significant anisotropy in the ferroelectric properties of the textured BIT ceramics. This work demonstrates the anisotropic arrangement of the oxygen vacancy defects and its effect on the electrical properties of high-temperature bismuth layer-structured ferroelectrics.     

Effect of long-chain branching molar fraction on scratch behavior of polypropylene

Polymers containing a certain amount of long-chain-branching (LCB) structure are expected to possess improved mechanical properties over those of the linear structure counterpart. However, fundamental knowledge on the structure–property relationship in LCB containing polypropylene (PP) is still illusive. In the present study, a set of model PP systems containing an increasing molar fraction of LCB (5–19 mol%) were prepared by reactive extrusion to determine how LCB content may influence the scratch behavior of PP. It is shown that with only 5 mol% of LCB content in PP can improve resistance against scratch-induced fish-scale formation by over 25%. The improvement of scratch resistance is attributed to the increases in entanglement density in LCB-containing PPs, which is evidenced by their creep-recovery behavior. The present study demonstrates that the incorporation of LCB in PP leads to higher viscoelastic recovery and increased tensile strength, which account for the observed improvement in scratch performance. The usefulness of LCB in polymers for improving scratch performance is discussed.     

Metformin Preserves β-Cell Compensation in Insulin Secretion and Mass Expansion in Prediabetic Nile Rats

Prediabetes is a high-risk condition for type 2 diabetes (T2D). Pancreatic β-cells adapt to impaired glucose regulation in prediabetes by increasing insulin secretion and β-cell mass expansion. In people with prediabetes, metformin has been shown to prevent prediabetes conversion to diabetes. However, emerging evidence indicates that metformin has negative effects on β-cell function and survival. Our previous study established the Nile rat (NR) as a model for prediabetes, recapitulating characteristics of human β-cell compensation in function and mass expansion. In this study, we investigated the action of metformin on β-cells in vivo and in vitro. A 7-week metformin treatment improved glucose tolerance by reducing hepatic glucose output and enhancing insulin secretion. Although high-dose metformin inhibited β-cell glucose-stimulated insulin secretion in vitro, stimulation of β-cell insulin secretion was preserved in metformin-treated NRs via an indirect mechanism. Moreover, β-cells in NRs receiving metformin exhibited increased endoplasmic reticulum (ER) chaperones and alleviated apoptotic unfold protein response (UPR) without changes in the expression of cell identity genes. Additionally, metformin did not suppress β-cell mass compensation or proliferation. Taken together, despite the conflicting role indicated by in vitro studies, administration of metformin does not exert a negative effect on β-cell function or cell mass and, instead, early metformin treatment may help protect β-cells from exhaustion and decompensation.     

Endothelin ETB Receptor-Mediated Astrocytic Activation: Pathological Roles in Brain Disorders

In brain disorders, reactive astrocytes, which are characterized by hypertrophy of the cell body and proliferative properties, are commonly observed. As reactive astrocytes are involved in the pathogenesis of several brain disorders, the control of astrocytic function has been proposed as a therapeutic strategy, and target molecules to effectively control astrocytic functions have been investigated. The production of brain endothelin-1 (ET-1), which increases in brain disorders, is involved in the pathophysiological response of the nervous system. Endothelin B (ET_B) receptors are highly expressed in reactive astrocytes and are upregulated by brain injury. Activation of astrocyte ET_B receptors promotes the induction of reactive astrocytes. In addition, the production of various astrocyte-derived factors, including neurotrophic factors and vascular permeability regulators, is regulated by ET_B receptors. In animal models of Alzheimer’s disease, brain ischemia, neuropathic pain, and traumatic brain injury, ET_B-receptor-mediated regulation of astrocytic activation has been reported to improve brain disorders. Therefore, the astrocytic ET_B receptor is expected to be a promising drug target to improve several brain disorders. This article reviews the roles of ET_B receptors in astrocytic activation and discusses its possible applications in the treatment of brain disorders.     

Achieving excellent energy storage density of Pb0.97La0.02(ZrxSn0.05Ti0.95-x)O3 ceramics by the B-site modification

The applications of antiferroelectric (AFE) materials in miniaturized and integrated electronic devices are limited by their low energy density. To address the above issue, the antiferroelectricity of the reinforced material was designed to improve its AFE-ferroelectric (FE) phase transition under electric fields. In this present study, the composition of Zr⁴⁺ (0.72 Å) and Ti⁴⁺ (0.605 Å) at B-site of Pb_0.97La_0.02(Zr_xSn_0.05Ti_0.95-x)O₃ ceramics with orthogonal reflections are synthesized via the tape-casting method. These ceramics are modified to enhance their antiferroelectricity by reducing their tolerance factor. A recoverable energy storage density W_rec 12.1 J/cm³ was obtained for x = 0.93 under 376 kV/cm, which is superior value than reported until now in lead-based energy storage systems. Moreover, the discharge energy density can reach 10.23 J/cm³, and 90 % of which can be released within 5.66 μs. This work provides a new window and potential materials for further industrialization of pulse power capacitors.     

粮油食品防霉微生物筛选及其活性物质初步研究

为开发新型防霉剂，降低粮油食品储藏、运输、流通等过程中霉变对其品质和食用安全的影响，研究筛选获得具有强防霉活性的微生物。采用抑菌圈法，以禾谷镰刀菌（Fusarium graminearum）为指示菌筛选具有防霉活性的菌株。利用形态学观察、生化特征鉴定和16S rDNA基因序列比对进行菌株鉴定；通过不同温度、pH和蛋白酶K处理对防霉活性物质进行初步分析。结果显示：通过初筛获得33株对禾谷镰刀菌具有强抑制活性的菌株，复筛后选择的7株菌归属为芽孢杆菌属（Bacillus）；活性物质分析发现7株菌的活性物质均不耐高温和强酸碱，同时蛋白酶K处理对其防霉效果没有明显影响，初步推断为肽类；通过抑菌谱测定发现菌株ASAG 62对常见霉菌（产黄青霉Penicillium flavum、黑曲霉Aspergillus Niger、赭曲霉Aspergillus ochre、黄曲霉Aspergillus flavus、禾谷镰刀菌F. graminearum）均具有良好的抑制效果。     

印刷电路板缺陷检测的实际应用

电路板在我们的日常生活中非常常见,这就使得印刷电路板的缺陷检测显得尤为重要。AOI作为新兴的检测PCB板缺陷的系统,在生产实际中正在被大家熟知并且应用。相较于传统的检测方式,AOI系统比较灵活,无论是在检测时间还是系统运算上,或者是对相关技术人员的要求相较于传统方式都比较有优势,本文就AOI系统在实际中的应用展开讨论,分析并且介绍了在实际应用中的具体细则。     

面向平板结构钙钛矿太阳能电池的金属氧化物综述

作为平板结构钙钛矿太阳能电池的电荷传输层，金属氧化物薄膜对器件性能有重要影响. 系统性概述平板结构钙钛矿太阳能电池对金属氧化物薄膜形貌、电学、光学、化学及热等物理特性要求，并对目前在高效钙钛矿太阳电池制备中最有前景的金属氧化物电子传输层及空穴传输层材料特性及代表性工作进行总结. 针对大多数金属氧化物迁移率低、表面缺陷多及能级匹配差的问题，分析元素掺杂、表面改性、复合薄膜设计等手段解决的相关进展. 总结目前金属氧化物薄膜沉积技术现状及优缺点，探讨今后薄膜沉积技术发展、改进方向. 对低温沉积金属氧化物薄膜在柔性器件方面的应用进行展望.     

In Vitro Macrophage Immunomodulation by Poly(ε-caprolactone) Based-Coated AZ31 Mg Alloy

Due to its excellent bone-like mechanical properties and non-toxicity, magnesium (Mg) and its alloys have attracted great interest as biomaterials for orthopaedic applications. However, their fast degradation rate in physiological environments leads to an acute inflammatory response, restricting their use as biodegradable metallic implants. Endowing Mg-based biomaterials with immunomodulatory properties can help trigger a desired immune response capable of supporting a favorable healing process. In this study, electrospun poly(ε-caprolactone) (PCL) fibers loaded with coumarin (CM) and/or zinc oxide nanoparticles (ZnO) were used to coat the commercial AZ31 Mg alloy as single and combined formulas, and their effects on the macrophage inflammatory response and osteoclastogenic process were investigated by indirect contact studies. Likewise, the capacity of the analyzed samples to generate reactive oxygen species (ROS) has been investigated. The data obtained by attenuated total reflection Fourier-transform infrared (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analyses indicate that AZ31 alloy was perfectly coated with the PCL fibers loaded with CM and ZnO, which had an important influence on tuning the release of the active ingredient. Furthermore, in terms of degradation in phosphate-buffered saline (PBS) solution, the PCL-ZnO- and secondary PCL-CM-ZnO-coated samples exhibited the best corrosion behaviour. The in vitro results showed the PCL-CM-ZnO and, to a lower extent, PCL-ZnO coated sample exhibited the best behaviour in terms of inflammatory response and receptor activator of nuclear factor kappa-B ligand (RANKL)-mediated differentiation of RAW 264.7 macrophages into osteoclasts. Altogether, the results obtained suggest that the coating of Mg alloys with fibrous PCL containing CM and/or ZnO can constitute a feasible strategy for biomedical applications.