Molecular dynamic study of temperature dependence of mechanical properties and plastic inception of CoCrCuFeNi high-entropy alloy

Molecular dynamics simulations are performed to study mechanical characteristics and homogeneous plastic inception of CoCrCuFeNi high-entropy alloy at various temperatures under uniaxial tension. It is found that the elastic modulus and ultimate tensile strength increase with temperature decreasing. A notable softening effect is observed at the elastic deformation stage caused by the decrease of the interatomic force gradient. Extrinsic stacking faults and deformation twins are extensively observed, which are formed via intrinsic stacking faults overlap.     

光子晶体光纤温度压力传感器

提出了一种在高温环境下同时测量温度和气压的光子晶体光纤温度压力传感器.在普通单模光纤和光子晶体光纤之间熔接一段空心光纤构成干涉结构.空心光纤段构成非本征法布里-珀罗干涉仪,利用光子晶体光纤的微孔与外界相通,通过气体折射率变化来测量环境中的气压变化;光子晶体光纤段构成本征法布里-珀罗干涉仪,利用热膨胀效应和热光效应来测量环境中的温度.传感器的解调通过自制的白光干涉解调仪实现,实验通过测量腔长得到被测环境的温度和气压.在不同温度和气压环境下,对腔长分别为306μm和1535μm的温度压力光纤传感器进行连续测量.实验结果表明,传感器能够在28~800℃的温度下和0~10 MPa的气压下稳定工作,测量范围内温度灵敏度可达17.4 nm/℃,压力灵敏度随温度增加而降低,在28℃时可达1460.5 nm/MPa.     

Characteristic material parameters of CIGS solar cell related with device performance

CIGS solar cells with power conversion efficiency (PCE) in the range of 1.82%–12.30% were obtained by using two-step process, and were further analyzed through various measurement techniques. Material parameters showed diverse values and some trends depending on the device performance. The lower performance device showed small integrated PL intensity, short minority life time, larger defect density and lower activation energy, whereas the higher performance device showed opposite values. We investigated relationship between material parameters and PCE of solar cells, and found that some physical parameters such as integrated PL intensity, minority life time, defect density, and difference between band gap and activation energy (E_g-E_a), which all reflect defect states in bulk and at pn interface, are strongly related with PCE and would be used as a good indicator to evaluate device performance quickly.     

Multiplasmid DNA in agarose gel electrophoresis: Suitable dye and temperature is essential for prominent profiles

Nucleic acids dye Goldview is widely used in agarose gel electrophoresis (AGE). However, in this study, a sample of multiplasmid DNA (multi-pDNA) stained with Goldview analyzed by AGE showed its instability at low temperature. Three types of DNA samples were analyzed, including linear DNA (ladder), single-plasmid DNA (single-pDNA), and multi-pDNA, electrophoretic conditions were optimized by adjusting the dye, the buffer, and the temperature (1–50°C). The results showed that the light intensity of Gelred is 2.2-times higher than that of Goldview in staining multi-pDNA. Compared with the single-pDNA and the linear DNA, the multi-pDNA stained with Goldview was greatly affected by temperature. This short communication indicated that Gelred is a highly applicable dye for analyzing multiplasmid samples. The degree and the way of binding of Goldview to multi-pDNA are greatly affected by temperature.     

Cobalt ferrite for direct cracking of methane to produce hydrogen and carbon nanostructure: Effect of temperature and methane flow rate

Cobalt ferrite (CoFe₂O₄) was used as a catalyst for direct methane cracking. The reaction was accomplished in a fixed bed reactor at normal atmospheric pressure, while gas flow rate (20–50 mL/min) and reaction temperature (800–900 °C) were varied. The fresh CoFe₂O₄ morphology is sponge-like particle with inverse spinel structure as revealed from SEM and XRD results. The methane conversions and hydrogen formation rate were increased with reaction temperature, while catalyst stability and induction period decreased. Increases of gas flow rate > 20 mL/min led to a decrease the overall catalytic activity of CoFe₂O₄ for methane cracking. The XRD results of spent catalysts revealed that CoFe alloy was the active phase of methane cracking. TGA analysis showed that the largest amount of deposited carbon was 70.46 % at (20 mL/min, 900 °C), where it was 34.40 % at (50 mL/min, 800 °C). The deposited carbon has the shape of spherical carbon nanostructures and/or nano sprouts as observed with SEM. Raman data confirmed the graphitization type of the deposited carbon.     

Amperometric Detection of Ethanol Vapors by Screen Printed Electrodes Modified by Paper Crowns Soaked with Room Temperature Ionic Liquids

A convenient assembly recently proposed for screen printed gold electrodes (SPEs) suitable for measurements in gaseous samples is here tested for the analysis of the ethanol content in alcoholic drinks. This assembly involves the use of a circular crown of filter paper, soaked in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hydrogen sulfate, which is simply placed upon a disposable screen printed cell, so as to contact the outer edge of the gold disc working electrode, as well as peripheral counter and reference electrodes. The electrical contact between the paper crown soaked in RTIL and the SPE electrode is assured by a gasket and all components are installed in a polylactic acid holder. This assembly provides a portable and disposable electrochemical platform, assembled by the easy immobilization onto a porous and inexpensive supporting material such as paper of a RTIL characterized by profitable electrical conductivity and negligible vapor pressure. The electroanalytical performance of this device was assayed for the flow injection analysis of the ethanol concentration in some real samples of wine and beer and the results obtained are compared with the alcoholic degree reported in the relevant bottle-labels, thus highlighting a substantially satisfactory agreement. Repeatable sharp peaks (RSD=6–8 %) were detected for ethanol over a wide linear range (1–20 % v/v in water) and a detection and quantitation limit of 0.55 % v/v and 1.60 % v/v were inferred for a signal-to-noise ratio of 3 and 10, respectively.     

Minimizing Temperature Bias through Reliable Temperature Determination in Gas-Solid Photothermal Catalytic Reactions

Enormous advances in photothermal catalysis have been made over the years, whereas the temperature assessment still remains controversial in the majority of photothermal catalytic systems. Herein, we methodically uncovered the phenomenon of temperature determination bias arising from prominent temperature differences in gas-solid photothermal catalytic systems, which extensively existed yet has been overlooked in most relevant cases. To avoid the interference of temperature bias, we developed a universal protocol for reliable temperature evaluation of gas-solid photothermal catalytic reactions, with emphasis on eliminating the temperature gradient and temperature fluctuation of catalyst layer via optimizing the reaction system. This work presents a functional and credible practice for temperature detection, calling attention to addressing the effects of temperature differences, and reassessing the actual temperature-based performances in gas-solid photothermal catalysis.     

Modulating Triplet Excited States of Organic Semiconductors via Tuning Molecular Conformation for Dual-ratiometric Thermometers

The dual-ratiometric thermometry is one of highly accurate methods for microscopic thermal measurement in biological systems. Herein, a series of chromone derivatives with noncovalently intramolecular interactions (NIIs) were designed and synthesized for ratiometric thermometers. The triplet states of these organic compounds were systematically tuned upon regulating the conformation with NIIs to yield efficient room temperature phosphorescence and large wavelength difference between fluorescence and phosphorescence simultaneously. As a result, an unprecedent organic 3D dual-ratiometric thermometer was established based on the intensity ratio and lifetime ratio of fluorescence/phosphorescence vs temperature, which was used for in vitro and in vivo bio-thermometry with high accuracy. This work provides a novel method to achieve organic dual ratiometric thermometers via tuning the triplet excited states.     

Supercooled Liquids with Dynamic Room Temperature Phosphorescence Using Terminal Hydroxyl Engineering

Dynamic room temperature phosphorescence (RTP) materials have potential applications in optoelectronics, which inevitably suffer from poor processability, flexibility or stretchability. Herein, we report a concise strategy to develop supercooled liquids (SCLs) with dynamic RTP behavior using terminal hydroxyl engineering. The terminal hydroxyls effectively hinder the nucleation process of molecules for the formation of stable SCLs after thermal annealing. Impressively, the SCLs show reversible RTP emission via alternant stimulation by UV light and heat. Photoactivated SCLs have phosphorescent efficiency of 8.50 % and a lifetime of 31.54 ms under ambient conditions. Regarding the dynamic RTP behavior and stretchability of SCLs, we demonstrate the applications in erasable data encryption and patterns on flexible substrates. This finding provides a design principle for obtaining SCLs with RTP and expands the potential applications of RTP materials in flexible optoelectronics.     

Robust and Wide Temperature-Range Zinc Metal Batteries with Unique Electrolyte and Substrate Design

Rechargeable zinc metal batteries are promising for large-scale energy storage. However, their practical application is limited by harsh issues such as uncontrollable dendrite growth, low Coulombic efficiency, and poor temperature tolerance. Herein, a unique design strategy using γ-valerolactone-based electrolyte and nanocarbon-coated aluminum substrate was reported to solve the above problems. The electrolyte with extremely low freezing point and high thermal stability enables the symmetric cells with long cycle life over a wide temperature range (−50 °C to 80 °C) due to its ability to regulate zinc nucleation and preferential epitaxial growth. Besides, the nanocarbon-coated aluminum substrate can also promote a higher Coulombic efficiency over a wide temperature range in contrast to the low Coulombic efficiency of copper substrates with significant irreversible alloying reactions because this unique substrate with excellent chemical stabilization can homogenize the interfacial electron/ion distribution. The optimized zinc metal capacitors can operate stably under various temperature conditions (2000 cycles at 30 °C with 66 % depth of discharge and 1200 cycles at 80 °C with 50 % depth of discharge). This unique electrolyte and substrate design strategy achieves a robust zinc metal battery over a wide temperature range.