Toward revealing atomic deformation mechanics in lithium disilicate and β-quartz containing glass-ceramics

The mechanics of glass-ceramics subjected to sharp contact or other loading conditions remain elusive, even after being commercialized in many industrial applications. We present work herein to reveal atomic details of such deformations that are otherwise extremely difficult to probe experimentally for a lithium disilicate (LS2) and β-quartz containing glass-ceramics via molecular dynamics simulations. Specifically, the materials are comprised of LS2 and β-quartz nanocrystals in a residual glass matrix. Regardless of the deformation mechanism, whether it be nanoindentation or crack propagation for samples with pre-existing flaws, we observe that the LS2 nanocrystal itself undergoes substantial deformation, either by activating dislocations, forming an amorphization zone, or by initiating microcracks at glass-crystal interfaces or weak crystallographic planes. In contrast, the β-quartz nanocrystal is not easily deformed and remains almost intact with minimal plastic deformation, thereby forcing shear flow and crack propagation pathways to predominately occur in the residual glass and/or at interfaces. The dramatic difference between the crystalline phases also manifests itself in the deformation mode of interfaces under pure shear loading, in which shear bands preferably occur at the LS2-glass interfaces, while cavities form at the β-quartz-glass interfaces. These observations significantly advance our understanding of glass-ceramics and pave ways to exploit the understanding for more applications.     

Tribological Characteristics of Aqueous Graphene Oxide,Graphitic Carbon Nitride,and Their Mixed Suspensions

The tribological performance of graphene oxide (GO), graphitic carbon nitride (g-C₃N₄), and their mixed (g-C₃N₄/GO) aqueous suspensions was investigated. The 0.06 wt% GO, 0.06 wt% g-C₃N₄, and 0.06 wt% 1:1 g-C₃N₄/GO suspensions reduced the coefficient of friction (COF) by 37, 26 and 37% and wear mark radius by 19.1, 16.0 and 19.6%, respectively, in comparison with water. Pure g-C₃N₄ and GO suspensions showed unstable lubrication in the tests with relatively high loads and speeds, while the g-C₃N₄/GO mixed suspension had superior tribological performance in all tested conditions. This is because in the mixed suspension g-C₃N₄ agglomerates became smaller, and GO nanosheets exhibited fewer wrinkles and less stacking, which enabled the formation of a layer of tribo-composite film. As a result, the friction, wear and tribo-corrosion were reduced during sliding.     

Zirconium Diboride with High Thermal Conductivity

Thermal properties were characterized for zirconium diboride produced by reactive hot pressing and compared to ZrB₂ ceramics that were hot pressed from commercial powders. No sintering additives were used in either process. Thermal conductivity was calculated from measured values of heat capacity, thermal diffusivity, and density for temperatures ranging from 298 to 2273 K. ZrB₂ produced by reactive hot pressing achieved near full density, but had a small volume fraction of ZrO₂, whereas hot‐pressed ZrB₂ contained porosity and carbon inclusions. Reactive hot pressing produced a ceramic with higher thermal diffusivity and heat capacity, resulting in thermal conductivities of 127 W·(m·K)^?1 at 298 K and 80 W·(m·K)^?1 at 2273 K, which were up to ~30% higher than typically reported for hot‐pressed ZrB₂.     

Optimization of CdTe thin‐film solar cell efficiency using a sputtered,oxygenated CdS window layer

A major source of loss in cadmium sulfide/cadmium telluride (CdS/CdTe) solar cells results from light absorbed in the CdS window layer, which is not converted to electrical current. This film can be made more transparent by oxygen incorporation during sputter deposition at ambient temperature. Prior to this work, this material has not produced high‐efficiency devices on tin oxide‐coated soda‐lime‐glass substrates used industrially. Numerous devices were fabricated over a variety of process conditions to produce an optimized device. Although the material does not show a consistent increase in band gap with oxygenation, absorption in this layer can be virtually eliminated over the relevant spectrum, leading to an increase in short‐circuit current. Meanwhile, fill factor is maintained, and open‐circuit voltage increases relative to baseline devices with sublimated CdS. The trend of device parameters with oxygenation and thickness is consistent with an increasing conduction band offset at the window/CdTe interface. Optimization considering both initial efficiency and stability resulted in a National Renewable Energy Laboratory verified 15.2%‐efficient cell on 3.2‐mm soda‐lime glass. This window material was shown to be compatible with SnO₂‐based transparent conducting oxide and high resistance transparent coated substrates using in‐line compatible processes. Copyright © 2015 John Wiley & Sons, Ltd     

Molecular Characterisation of Flavanone O-methylation in Eucalyptus

Flavonoids are ubiquitous polyphenolic compounds in plants, long recognised for their health-promoting properties in humans. Methylated flavonoids have received increasing attention due to the potential of methylation to enhance medicinal efficacy. Recently, Eucalyptus species with high levels of the O-methylated flavanone pinostrobin have been identified. Pinostrobin has potential commercial value due to its numerous pharmacological and functional food benefits. Little is known about the identity or mode of action of the enzymes involved in methylating flavanones. This study aimed to identify and characterise the methyltransferase(s) involved in the regiospecific methylation of pinostrobin in Eucalyptus and thereby add to our limited understanding of flavanone biosynthesis in plants. RNA-seq analysis of leaf tips enabled the isolation of a gene encoding a flavanone 7-O-methyltransferase (EnOMT1) in Eucalyptus. Biochemical characterisation of its in vitro activity revealed a range of substrates upon which EnOMT1 acts in a regiospecific manner. Comparison to a homologous sequence from a Eucalyptus species lacking O-methylated flavonoids identified critical catalytic amino acid residues within EnOMT1 responsible for its activity. This detailed molecular characterisation identified a methyltransferase responsible for chemical ornamentation of the core flavanone structure of pinocembrin and helps shed light on the mechanism of flavanone biosynthesis in Eucalyptus.     

Simulating the Feasibility of Using Liquid Micro-Jets for Determining Electron–Liquid Scattering Cross-Sections

The extraction of electron–liquid phase cross-sections (surface and bulk) is proposed through the measurement of (differential) energy loss spectra for electrons scattered from a liquid micro-jet. The signature physical elements of the scattering processes on the energy loss spectra are highlighted using a Monte Carlo simulation technique, originally developed for simulating electron transport in liquids. Machine learning techniques are applied to the simulated electron energy loss spectra, to invert the data and extract the cross-sections. The extraction of the elastic cross-section for neon was determined within 9% accuracy over the energy range 1–100 eV. The extension toward the simultaneous determination of elastic and ionisation cross-sections resulted in a decrease in accuracy, now to within 18% accuracy for elastic scattering and 1% for ionisation. Additional methods are explored to enhance the accuracy of the simultaneous extraction of liquid phase cross-sections.     

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企业和顾客是一根绳上的蚱蜢,也是一对冤家。如何消除销售过程中具有对抗性的一面。成功说服顾客购买自己的产品。是许多企业的难题。     

Analogs of the Heat Shock Protein 70 Inhibitor MKT-077 Suppress Medullary Thyroid Carcinoma Cells

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor mainly caused by mutations in the RET proto-oncogene. We previously demonstrated that depletion of the mitochondrial molecular chaperone, mortalin, can effectively suppress human MTC cells in culture and in mouse xenografts, by disrupting mitochondrial bioenergetics and subsequently inducing apoptosis and RET downregulation. Similar effects were induced by MKT-077, a water-soluble rhodocyanine dye analog known to inhibit mortalin, but with notable toxicity in animals. These observations led us to evaluate recently developed MKT-077 analogs that exhibited higher selectivity to HSP70 proteins and improved bioavailability. We validated the MTC cell-suppressive effects of mortalin depletion in three-dimensional cultures of the human MTC lines, TT, and MZ-CRC-1, and then evaluated different MKT-077 analogs in two- and three-dimensional cell cultures, to show that the MKT-077 analogs, JG-98 and JG-194, effectively and consistently inhibited propagation of TT and MZ-CRC-1 cells in these cultures. Of note, these compounds also effectively suppressed the viability of TT and MZ-CRC-1 progenies resistant to vandetanib and cabozantinib. Moreover, JG-231, an analog with improved microsomal stability, consistently suppressed TT and MZ-CRC-1 xenografts in mice. These data suggest that mortalin inhibition may have therapeutic potential for MTC.     

RB Regulates DNA Double Strand Break Repair Pathway Choice by Mediating CtIP Dependent End Resection

Inactivation of the retinoblastoma tumor suppressor gene (RB1) leads to genome instability, and can be detected in retinoblastoma and other cancers. One damaging effect is causing DNA double strand breaks (DSB), which, however, can be repaired by homologous recombination (HR), classical non-homologous end joining (C-NHEJ), and micro-homology mediated end joining (MMEJ). We aimed to study the mechanistic roles of RB in regulating multiple DSB repair pathways. Here we show that HR and C-NHEJ are decreased, but MMEJ is elevated in RB-depleted cells. After inducing DSB by camptothecin, RB co-localizes with CtIP, which regulates DSB end resection. RB depletion leads to less RPA and native BrdU foci, which implies less end resection. In RB-depleted cells, less CtIP foci, and a lack of phosphorylation on CtIP Thr847, are observed. According to the synthetic lethality principle, based on the altered DSB repair pathway choice, after inducing DSBs by camptothecin, RB depleted cells are more sensitive to co-treatment with camptothecin and MMEJ blocker poly-ADP ribose polymerase 1 (PARP1) inhibitor. We propose a model whereby RB can regulate DSB repair pathway choice by mediating the CtIP dependent DNA end resection. The use of PARP1 inhibitor could potentially improve treatment outcomes for RB-deficient cancers.