Third order optical nonlinearities characteristics of Disperse Red1 organic dye molecules inside of polymeric nanocapsules

Measuring nonlinear optical response of a specific material in a mixture, not only leads to investigate the behavior of a particular component in various circumstances, but also can be a way to select suitable combination and optimum concentration of additives and therefore obtaining the maximum nonlinear optical signals. In this work, by using dual-arm Z-scan technique, the nonlinear refractive index of Disperse Red1 (DR1) organic dye molecules inside the core of prepared polymeric nanocapsules was measured among various materials which prepared nanocapsules were made of them. Then the measured value was compared with nonlinear refractive index of DR1 solved in dichloromethane.     

Crystallization of progesterone polymorphs using polymer-induced heteronucleation (PIHn) method

Progesterone is a natural hormone steroid used in humans for several treatments and in livestock for artificial insemination, which exhibits two polymorphic forms at ambient conditions: form 1 and form 2. Form 2 is metastable and more soluble than form 1; however, it is not suitable to use as powder raw material because it transforms into form 1 by the effects of grinding. A polymorphic screening of progesterone based on polymer-induced heteronucleation method was performed as an alternative to prepare the metastable form. Polyvinyl alcohol, hydroxypropyl methylcellulose (HPMC), dextran, gelatin, polyisoprene (PI) and acrylonitrile-butadiene (NBR) copolymer were used. Crystals were prepared from 0.5, 10 and 40?mg/mL solutions in acetone at room temperature by solvent evaporation. The samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), scanning electron microcopy and attenuated total reflectance infrared Fourier transform spectroscopy. Form 1 was nucleated from 40?mg/mL solutions on the six polymers and from 10?mg/mL solutions on PI and NBR. The mixture of form 1 and form 2 was obtained from 10?mg/mL solution on HPMC, dextran and gelatin and from 0.5?mg/mL solution crystallizations. Therefore, the polymeric devices, which crystallized the metastable and more soluble polymorph (2) of progesterone, would be a promissory alternative for the pharmaceutical applications.     

凉感纤维织物导热系数影响因素的探讨

采用普通涤纶、含1%云母颗粒的涤纶(1%云母/涤纶)以及含5%云母颗粒的涤纶(5%云母/涤纶)三种材质,上机纬密采用200根/10 cm、300根/10 cm、400根/10 cm,组织采用平纹、斜纹、缎纹试织试样。通过Hot Disk热常数分析仪,采用正交试验及极差、方差分析,研究了纤维材质、上机纬密、组织对凉感纤维织物导热系数的影响。结果表明:在试验设置变量范围内,纤维材质对导热系数的影响显著,上机纬密、组织对导热系数的影响高度显著,影响因素从大到小顺序为上机纬密>组织>纤维材质。     

Chloride migration in concrete with superabsorbent polymers

Superabsorbent polymers (SAP) can be used as a means for internal curing of concrete. In the present study, the development of transport properties of concrete with SAP is investigated. The chloride migration coefficient according to NT BUILD 492 is used as a measure of this. Twenty concrete mixtures are tested 7, 14, and 28 days after casting. The development of degree of hydration is followed for 20 corresponding paste mixtures.Both when SAP is added with extra water to compensate the SAP water absorption in fresh concrete and without extra water, the internal curing water held by SAP may contribute to increase the degree of hydration. No matter if SAP is added with or without extra water, it appears that the so-called gel space ratio can be used as a key parameter to link age and mixture proportions (water-to-cement ratio and SAP dosage) to the resulting chloride migration coefficient; the higher the volume of gel solid relative to the space available for it, the lower the chloride migration coefficient, because the pore system becomes more tortuous and the porosity becomes less.     

Mixed-Metal MOF-74 Templated Catalysts for Efficient Carbon Dioxide Capture and Methanation

The vast chemical and structural tunability of metal–organic frameworks (MOFs) are beginning to be harnessed as functional supports for catalytic nanoparticles spanning a range of applications. However, a lack of straightforward methods for producing nanoparticle-encapsulated MOFs as efficient heterogeneous catalysts limits their usage. Herein, a mixed-metal MOF, NiMg-MOF-74, is utilized as a template to disperse small Ni nanoclusters throughout the parent MOF. By exploiting the difference in Ni O and Mg O coordination bond strength, Ni²⁺ is selectively reduced to form highly dispersed Ni nanoclusters constrained by the parent MOF pore diameter, while Mg²⁺ remains coordinated in the framework. By varying the ratio of Ni to Mg in the parent MOF, accessible surface area and crystallinity can be tuned upon thermal treatment, influencing CO₂ adsorption capacity and hydrogenation selectivity. The resulting Ni nanoclusters prove to be an active catalyst for CO₂ methanation and are examined using extended X-ray absorption fine structure and X-ray photoelectron spectroscopy. By preserving a segment of the Mg²⁺-containing MOF framework, the composite system retains a portion of its CO₂ adsorption capacity while continuing to deliver catalytic activity. The approach is thus critical for designing materials that can bridge the gap between carbon capture and CO₂ utilization.     

Process and joint quality of ultrasonic vibration enhanced friction stir lap welding

In order to improve the process effectiveness and joint quality, ultrasonic vibrations were integrated with friction stir lap welding. Effect of ultrasonic exertion on the process and joint quality of AA 6061-T6 were investigated. Upon ultrasonic exertion, joints owned larger effective lap width, shorter hooks and improved strength. Weld fracture mode changed from a ductile–brittle mixed mode to a more ductile mode while the fracture path shifted from lap interface to beyond the stir zone. Material flow and interface defects were characterised using lap welded dissimilar aluminium alloy joints. Ultrasonic vibration improved the material flow and reduced the interfacial defects. Variations in failure load of joints were found in accordance with the variations in material flow and interfacial defects.     

Measurement of Electrophysiological Signals In Vitro Using High-Performance Organic Electrochemical Transistors

Biological environments use ions in charge transport for information transmission. The properties of mixed electronic and ionic conductivity in organic materials make them ideal candidates to transduce physiological information into electronically processable signals. A device proven to be highly successful in measuring such information is the organic electrochemical transistor (OECT). Previous electrophysiological measurements performed using OECTs show superior signal-to-noise ratios than electrodes at low frequencies. Subsequent development has significantly improved critical performance parameters such as transconductance and response time. Here, interdigitated-electrode OECTs are fabricated on flexible substrates, with one such state-of-the-art device achieving a peak transconductance of 139 mS with a 138 µs response time. The devices are implemented into an array with interconnects suitable for micro-electrocorticographic application and eight architecture variations are compared. The two best-performing arrays are subject to the full electrophysiological spectrum using prerecorded signals. With frequency filtering, kHz-scale frequencies with 10 µV-scale voltages are resolved. This is supported by a novel quantification of the noise, which compares the gate voltage input and drain current output. These results demonstrate that high-performance OECTs can resolve the full electrophysiological spectrum and suggest that superior signal-to-noise ratios could be achieved in high frequency measurements of multiunit activity.     

硅渣和玻璃粉直接烧结制备多孔材料的气孔结构与力学性能

以硅渣和玻璃粉为原料,采用粉体直接烧结法制备多孔材料,研究了烧结温度(700~900℃)、烧结时间(15~120min)和升温速率(10~100℃·min^-1)对多孔材料表观密度、气孔率、物相组成、抗压强度的影响。结果表明:气孔结构均匀性随烧结温度的升高而降低;表观密度随烧结温度的升高先减小后增大,随保温时间的延长而增大,随升温速率的增大而减小,气孔率的变化趋势与表观密度的相反;多孔材料的主要物相为玻璃相和硅、SiC、SiO2、Ca2Al2SiO7等结晶相,且结晶度随烧结温度的升高而降低;抗压强度随烧结温度的升高呈先增大后减小的趋势;当烧结温度为750℃,升温速率为30℃·min^-1,烧结时间为30 min时,多孔材料的主晶相为硅和Ca2Al2SiO7,抗压强度最大(1.60MPa),表观密度为0.43g·cm^-3,气孔率为80%。     

不同有机物对硝酸盐氮测试的影响

研究了红糖、葡萄糖、乙酸钠、甲醇、乙醇、乙酸、丙酸、丁酸、正戊酸、混合有机溶剂等10种不同有机物对麝香草酚光谱法和离子色谱法测试硝酸盐氮的影响。结果表明,溶液中含有红糖或葡萄糖时,均会对麝香草酚法测试硝酸盐氮造成影响,使得测试结果偏大;在无硝酸根离子存在时,红糖和葡萄糖的质量浓度与硝酸盐氮的测试浓度非线性相关;而乙酸钠、甲醇、乙醇、乙酸、丙酸、丁酸、正戊酸和混合有机溶剂则对麝香草酚法测试硝酸盐氮没有影响。实验发现,红糖和葡萄糖在浓硫酸的作用下与麝香草酚发生Molisch反应,形成有色复合物和红棕色不溶性沉淀。实验采用离子色谱法测试硝酸盐氮时,红糖和葡萄糖等糖类有机物对测试结果均无影响。     

In situ measurements of human cough aerosol hygroscopicity

The airborne dynamics of respiratory droplets, and the transmission routes of pathogens embedded within them, are governed primarily by the diameter of the particles. These particles are composed of the fluid which lines the respiratory tract, and is primarily mucins and salts, which will interact with the atmosphere and evaporate to reach an equilibrium diameter. Measuring organic volume fraction (OVF) of cough aerosol has proved challenging due to large variability and low material volume produced after coughing. Here, the diametric hygroscopic growth factors (GF) of the cough aerosol produced by healthy participants were measured in situ using a rotating aerosol suspension chamber and a humidification tandem differential mobility analyser. Using hygroscopicity models, it was estimated that the average OVF in the evaporated cough aerosol was 0.88 ± 0.07 and the average GF at 90% relative humidity (RH) was 1.31 ± 0.03. To reach equilibrium in dry air the droplets will reduce in diameter by a factor of approximately 2.8 with an evaporation factor of 0.36 ± 0.05. Hysteresis was observed in cough aerosol at RH = ∼35% and RH = ∼65% for efflorescence and deliquescence, respectively, and may depend on the OVF. The same behaviour and GF were observed in nebulized bovine bronchoalveolar lavage fluid.