Hydrochromic CsPbBr3 Nanocrystals for Anti‐Counterfeiting

Hydrochromic materials that can reversibly change color upon water treatment have attracted much attention owing to their potential applications in diverse fields. Herein, for the first time, we report that space‐confined CsPbBr₃ nanocrystals (NCs) are hydrochromic. When CsPbBr₃ NCs are loaded into a porous matrix, reversible transition between luminescent CsPbBr₃ and non‐luminescent CsPb₂Br₅ can be achieved upon the exposure/removal of water. The potential applications of hydrochromic CsPbBr₃ NCs in anti‐counterfeiting are demonstrated by using CsPbBr₃ NCs@mesoporous silica nanospheres (around 100 nm) as the starting material. Owing to the small particle size and negatively charged surface, the as‐prepared particles can be laser‐jet printed with high precision and high speed. We demonstrate the excellent stability over repeated transformation cycles without color fade. This new discovery may not only deepen the understanding of CsPbX₃, but also open a new way to design CsPbX₃ materials for new applications.     

Optimization of l‐arginine purification from Corynebacterium crenatum fermentation broth

l ‐Arginine has many special physiological and biochemical functions, with wide applications in the food and pharmaceutical industry. Few studies on the purification of l ‐arginine from fermentation broth have been conducted; however, none of them were systematic enough for industrial scale‐up. Therefore, it is necessary to develop a highly efficient and systematic process for the purification of l ‐arginine from fermentation broth. In this study, we screened out a cation exchange resin, D155, having high exchange capacity, high selectivity, and easy elution capacity, and analyzed its adsorption isotherm, thermodynamics, and kinetics using different models. Further, the process parameters of fixed‐bed ion exchange adsorption and elution were optimized, and the penetration curve during the operation was modeled. Based on the fixed‐bed ion‐exchange parameters, a 30‐column continuous ion‐exchange system was designed, and the flow velocity in each zone was optimized. Finally, to obtain a high purity of l ‐arginine, the purification tests were conducted using anion exchange resin 711, and an l ‐arginine yield of 99.1% and purity of 98.5% was obtained. This effective and economical method also provides a promising strategy for separation of other amino acids from the fermentation broth, which is of great significance to the l ‐arginine fermentation industry.     

Periodic decentralized event-triggered control for nonlinear systems with asynchronous update and dynamic quantization

Nonlinear Dynamics - Periodic event-triggered control (PETC) is an aperiodic sampling technique aiming at reducing the working time of the sensors and the transmissions in the feedback control...     

交互模式-电感耦合等离子体质谱(ICP-MS)法测定生态地球化学植物样品中7种金属元素

植物样品中各元素的含量,是评价土壤质量及健康的重要指标。为满足测定大批量生态地球化学植物样品中多金属元素分析要求,建立了交互模式-电感耦合等离子体质谱(ICP-MS)法测定植物样品中7种痕量金属元素的定量分析方法。讨论了ICP-MS的STD、KED(He)、交互模式3种方法测定植物样品中7种金属元素结果。结果表明,利用工作曲线法配制Hg标准溶液,更改⁸²Se在线校正方程系数为1.83,在ICP-MS的交互模式下测定植物样品中⁸²Se、⁶³Cu、⁶⁰Ni、⁶⁶Zn、¹¹¹Cd、⁷⁵As、²⁰²Hg可以得到准确可靠的结果,克服了植物样品中Se和Hg元素测定的难题。基于所建方法各元素校准曲线系数>0.999,方法检出限为0.000 4～0.08 mg/kg,加标回收率在96.2%～107%,测定GBW10010a(大米)、GBW10012(玉米)、GBW10021(豆角)3种标准物质,结果均在参考值范围内,相对标...     

Multicaloric and coupled-caloric effects

The multicaloric effect refers to the thermal response of a solid material driven by simultaneous or sequential application of more than one type of external field.For practical applications,the multicaloric effect is a potentially interesting strategy to improve the efficiency of refrigeration devices.Here,the state of the art in multi-field driven multicaloric effect is reviewed.The phenomenology and fundamental thermodynamics of the multicaloric effect are well established.A number of theoretical and experimental research approaches are covered.At present,the theoretical understanding of the multicaloric effect is thorough.However,due to the limitation of the current experimental technology,the experimental approach is still in progress.All these researches indicated that the thermal response and effective reversibility of multiferroic materials can be improved through multicaloric cycles to overcome the inherent limitations of the physical mechanisms behind single-field-induced caloric effects.Finally,the viewpoint of further developments is presented.     

Fusion Domain-Adaptation CNN Driven by Images and Vibration Signals for Fault Diagnosis of Gearbox Cross-Working Conditions

The vibration signal of gearboxes contains abundant fault information, which can be used for condition monitoring. However, vibration signal is ineffective for some non-structural failures. In order to resolve this dilemma, infrared thermal images are introduced to combine with vibration signals via fusion domain-adaptation convolutional neural network (FDACNN), which can diagnose both structural and non-structural failures under various working conditions. First, the measured raw signals are converted into frequency and squared envelope spectrum to characterize the health states of the gearbox. Second, the sequences of the frequency and squared envelope spectrum are arranged into two-dimensional format, which are combined with infrared thermal images to form fusion data. Finally, the adversarial network is introduced to realize the state recognition of structural and non-structural faults in the unlabeled target domain. An experiment of gearbox test rigs was used for effectiveness validation by measuring both vibration and infrared thermal images. The results suggest that the proposed FDACNN method performs best in cross-domain fault diagnosis of gearboxes via multi-source heterogeneous data compared with the other four methods.     

CCD对高空间分辨率波前干涉检测的影响

推导并用实验验证了光强与入射波前在单位像元面积里成近似线性关系,从而得到入射波前经CCD采样后的功率谱密度（PSD）公式.根据该公式,模拟分析了影响CCD采集系统的系统传递函数的各个因素：入射波前、CCD的填充因子及CCD的曝光时间,得出了他们与系统传递函数的定性关系,并且通过实验明确CCD曝光时间对高空间分辨率波前检测不确定度的影响,为高空间分辨率干涉设计提供了理论依据.     

A novel method for making ultra-fine metal fibers and particles

A novel method based on plastic processing and equipment for preparing ultra-fine metal fibers and particles is reported. With this new method, metal fibers and particles can both be produced on the same equipment and the surfaces of the fibers and particles can be protected from oxidation by the polymers or solvents during the preparation process. Metal-alloy powders with lower melt point were filled into polymer by an extruder, followed by a die-drawing process at a temperature lower than the melt temperature of the metal alloy. Metal fibers or particles were obtained after the polymer matrix was washed away. Metal alloy fibers can be obtained when a polymer that strongly interacts with metal alloy, such as a special polyvinyl alcohol with a low alcoholysis degree, is used as the polymer matrix. Metal-alloy particles can be obtained when a polymer with weak interaction with metal alloy, such as polyethylene (PE), is used as the polymer matrix. Based on the principle of this new method, it is possible to produce finer or even nano-sized metal fibers and particles with higher melting points.     

半导体复合TiO2纳米光催化剂

对近年来利用半导体复合TiO2纳米光催化剂进行了介绍。总结了复合TiO2纳米光催化剂的制备、复合物的种类、光催化机理以及影响半导体复合TiO2光催化性能的因素。     

硫化物/Ru(Ⅱ)结合物复合敏化TiO_2纳米多孔膜

用光电化学方法研究了Cds、Pbs和RuL2（NCS）2（L＝2.2′-bipydine-4.4′-dicarboxylicacid）复合敏化TiO2。纳米晶电极的光电化学行为．结果表明，采用复合敏化比用rul（Ⅱ）络合物单独敏化TiO2。纳米晶电极效果好，大大提高了光电转换效率．主要原因是采用复合敏化，可防止TiO2导带上由光注入产生的电子的反向转移，避免了电子的损失．