Photonic theory of noise

The paper proposes that 1/f noise in materials and devices under non-equilibrium conditions is of electromagnetic origin rather than being related to charge carriers. For samples represented by simple resistors the analysis shows that the noise is due to the discrete nature of photons constituting the impinging electromagnetic flux from the source feeding the resistor. The paper presents detailed analysis of the external and internal electromagnetic fields of the resistor environment, with appropriate interpretation in terms of discrete photons. From quantum theory photons are known to retain their energy under interactions in linear environments. This property implies a departure from macroscopic electromagnetics in that photons cannot be partially transmitted and partially reflected, a phenomenon requiring appropriate modifications of boundary conditions at the resistor surface. These special demands call for inclusion of a supplementary internal resistor mode, serving as a lossless idler which is active only for matching purposes. At the resistor terminals the impinging photons give rise to excitation of RF current and voltage noise with an exact 1/f frequency distribution, which is in agreement with all available experimental measurements. The paper presents detailed formulae for noise spectral densities under general drive conditions from DC and RF sources of arbitrary internal resistance. The presented theoretical noise formulae have the same form as earlier empirical formulae for 1/f noise. With an RF source at frequency f₀ the analysis predicts noise with 1/|f-f₀| frequency distribution, which is compatible with available experimental observations.     

Creating an Air‐Stable Sulfur‐Doped Black Phosphorus‐TiO2 Composite as High‐Performance Anode Material for Sodium‐Ion Storage

With the increasing demand for low cost, long lifetime, high energy density storage systems, an extensive amount of effort has recently been focused on the development of sodium‐ion batteries (SIBs), and a variety of cathode materials have been discovered. However, looking for the most suitable anode material for practical application is a major challenge for SIBs. Herein, a high capacity sulfur‐doped black phosphorus‐TiO₂ (TiO₂‐BP‐S) anode material for SIBs is first synthesized by a feasible and large‐scale high‐energy ball‐milling approach, and its stability in air exposure is investigated through X‐ray photoelectron spectroscopy. The morphology of TiO₂‐BP‐S is characterized using transmission electron microscopy, indicating that the TiO₂ nanoparticles produce P? Ti bonds with BP. The TiO₂‐BP‐S composite with P? S and P? Ti bonds exhibits excellent stability in air and the superior electrochemical performance. For example, the discharge specific capacity is up to 490 mA h g^?1 after 100 cycles at 50 mA g^?1, and it remains at 290 mA h g^?1 after 600 cycles at 500 mA g^?1. Meanwhile, the scientific insight that the formation of stable P? S and P? Ti bonds can provide a guide for the practical large‐scale application of SIBs in other titanium base and black phosphorus materials is looked forward.     

晶硅太阳电池黑斑分析

p型单晶硅太阳电池在EL检测过程中,部分电池片出现黑斑现象.结合X射线能谱分析(EDS),对黑斑片与正常片进行对比分析,发现黑斑片电池与正常电池片大部分表面的成分相同,排除了镀膜及丝网印刷过程中产生黑斑的可能.利用X射线荧光光谱分析(XRF)测试了同一电池片的黑斑区域与正常区域,发现黑斑处Ca含量较大,并出现Sr、Ge和S等杂质元素.将6个档位的电池片制备成2 cm×2 cm的电池样片,利用光生诱导电流测量了每个电池的外量子效率(EQE).在460～1 000 nm波长范围内,同一电池片黑斑处与正常处的EQE相差较大,说明黑斑的出现与原生硅片缺陷无关,应归结于电池片生产过程中引入的杂质缺陷.给出了杂质引入的原因以及解决途径,从而显著减小了黑斑片产生的几率.     

纳米材料与微电极生物传感器

主要阐述了利用微电子机械加工技术制作一种新型的微电极集成生物传感器 ,并利用电化学方法在微电极表面固定超微粒的纳米材料 ,检验纳米材料对生物传感器稳定性、灵敏度、响应时间等影响。这种具有纳米尺度效应的生物传感器将在生物医学领域有着广阔的应用前景。     

绿茶汁澄清工艺的研究

比较池明矾、硅胶、高岭土、碱式氯化铝和聚丙烯酰胺５种物质对绿茶汁的洽效果,发现碱式氯化铝的澄清效果较好;通过Ｌ９（３＾４）正交实验优化,碱式氯化铝澄清绍茶汁适宜的条件为：ＰＨ＝６,用量０．１％和温度１５℃。     

超滤膜分离对绿茶茶水处理效果的影响

研究了超滤膜对绿茶茶水的分离效果 ,为超滤分离技术应用于绿茶饮料和茶多酚的工业生产提供了有关依据。研究结果表明 ,截留分子量小于 2 0 0 0 0的超滤膜 ,对茶水中的固形物、茶多酚的截留率分别高达 89%、 87% ;截留分子量高于 10 0 0 0 0的超滤膜可有效截留茶水中的大分子蛋白质和果胶类物质 ,改善了茶水的溶液特性 ,有利于茶多酚的工业生产 ;操作温度对茶水的超滤效果有显著影响。     

无木炭型黑火药研究

以酚酞和氢氧化钾的反应物替代木炭，通过调整硝酸钾、硫磺、酚酞及氢氧化钾的混合比例对无木炭黑火药配方进行优化设计，对比研究了普通黑火药与无木炭黑火药在机械感度、静电火花感度、热分解过程及输出特性等方面的差异。研究认为：无木炭黑火药的机械感度、静电火花感度、爆发点比普通黑火药低，而且安全性好，做功能力强，输出稳定性高。     

茶饮料保香及增香途径的探讨

介绍了茶叶原料的选择、焙火处理、杀菌技术、添加果胶酶处理、添加天然胡萝卜素和外源酶、香气回收技术等在茶饮料保香、增香上的应用,展望了其应用前景     

不同产地信息茶叶的红外光谱分析

通过规范化的标准检测, 制备样品并获取样品的标准红外光谱, 分别得到了几种中国名茶的标准红外光谱图。为了更全面地了解这些茶叶的整体地域特征, 建立了红外光谱分析的平均偏离方法, 对光谱图进行了的直观分析, 而且还探讨了平均偏离大小与茶叶产地纬度的关系。研究表明, 产地纬度相近的茶叶, 平均偏离小; 产地纬度相差大的茶叶, 平均偏离大。因此茶区的海拔高度和纬度与茶叶的产地信息有着密切关系, 平均偏离有可能成为分析茶叶产地信息的强有力的方法。     

Effect of the fabrication method on the electrical properties of poly(acrylonitrile-co-butadiene-co-styrene)/carbon black composites

Poly(acrylonitrile-co-butadiene-co-styrene) (ABS), an engineering plastic, was combined with carbon black (CB) to increase its conductivity. The ABS/CB composites were prepared using two different methods: dissolution of ABS in Butan-2-one and manual mixing of the constituent materials. These fabrication methods led to different microstructures, which led to vastly different electrical properties. The microstructures were acquired using scanning electron microscopy (SEM) and optical microscopy, while the electrical conductivity was obtained using impedance spectroscopy. The percolation threshold of the composites fabricated using the manual mixing method was found to be much lower (0.0054 vol.% CB) than that of the composites fabricated using the dissolution method (2.7 vol.% CB).