An immunoassay for bisphenol A based on direct hapten conjugation to the polystyrene surface of microtiter plates

Based on direct hapten coated format a competitive indirect enzyme-linked immunosorbent assay (ciELISA) for bisphenol A (BPA) was developed. Polystyrene surface was modified by 3-Aminopropyltriethoxysilane (APTES) to produce amino groups after H₂SO₄/HNO₃-pre-treatment. 4,4-bis (4-hydroxyphenyl) valeric acid (BVA) which is analogue of BPA, was successfully immobilized on the surface of microtiter plates by N,N′-dicyclohexylcarbodiimide (DCC) method. The essential steps of the assay were optimized, especially blocking procedure which is key step to prevent unspecific binding of antibody. The results indicated that compared with hapten-protein coated format (IC₅₀ = 176.67 ng ml⁻¹, LOD = 15.90 ng ml⁻¹), the direct hapten coated format (IC₅₀ = 23.50 ng ml⁻¹, LOD = 0.27 ng ml⁻¹) could improve assay sensitivity and the detection ranges were 2.30 ng∼157.60 ng ml⁻¹ with good signal reproducibility (P value > 0.05) after careful optimization of assay conditions. Tap water samples and seawater samples were spiked with a known amount of BPA and measured by ciELISA. The average recoveries were between 70 and 142%. As far as we are aware this is the most sensitive ELISA for BPA yet reported.     

Chemical oxidative degradation of Polybenzimidazole in simulated environment of fuel cells

The chemical oxidative degradation process of poly [2,2′-(m-phenylene)-5,5′-bibenzimidazole] (PBI) in simulated environment of fuel cells was evaluated. From the mechanical properties and the intrinsic viscosity of PBI, it was observed that the stress at break of PBI membranes decreased and the macromolecular chains of PBI were broken after the treatment in Fenton reagent for 24 h. From the photos of Scanning Electron Microscope, it was identified that there were lots of corroded holes in PBI membranes. By means of FTIR and ¹H NMR analysis, it was shown that during the treatment of PBI in the presence of HO or HOO free radicals the hydrogen atom of N-H bond in imidazole ring was liable to be oxidized, and the phenyl was oxidized with the formation of quinine and dicarboxylic acid structures. In the end, the possible mechanism of the chemical oxidative degradation of PBI was proposed.     

Measurements of effective delayed neutron fraction in a fast neutron reactor using the perturbation method

A perturbation method is proposed to obtain the effective delayed neutron fraction β_(eff) of a cylindrical highly enriched uranium reactor.Based on reactivity measurements with and without a sample at a specified position using the positive period technique,the reactor reactivity perturbation △ρ of the sample in β_(eff) units is measured.Simulations of the perturbation experiments are performed using the MCNP program.The PERT card is used to provide the difference dκ of effective neutron multiplication factors with and without the sample inside the reactor.Based on the relationship between the effective multiplication factor and the reactivity,the equation β~(eff)=dκ/△ρ is derived.In this paper,the reactivity perturbations of 13 metal samples at the designable position of the reactor are measured and calculated.The average β_(eff) value of the reactor is given as 0.00645,and the standard uncertainty is 3.0%.Additionally,the perturbation experiments for β_(eff) can be used to evaluate the reliabilities of the delayed neutron parameters.This work shows that the delayed neutron data of ~(235)U and ~(238)U from G.R.Keepin's publication are more reliable than those from ENDF-B6.0.ENDF-B7.0,JENDL3.3 and CENDL2.2.     

燃爆冲击作用下岩石初始破坏区形成机制与主控因素

为揭示燃爆冲击作用下井周岩石破坏区的形成机制,并分析影响初始破坏区(破碎区和初始裂隙区)的主控因素,开展了两种岩样在不同加载速率下的冲击破坏实验, 分析了岩石冲击破坏模式及岩石对加载速率的响应, 借助基于Von Mise准则建立的岩石冲击破坏的破碎区和初始裂隙区计算模型可知:加载速率低于190 GPa/s时,可依据冲击峰值压力引导的应力分布确定破碎区和初始裂隙区作用范围;燃爆压裂在近井地带主要产生破碎区和裂隙区,破碎区直径为井眼直径的1~3倍,初始裂隙区直径为井眼直径的5~7倍;冲击载荷作用下,初始破坏区与加载速率、脆性指数呈正相关,且受脆性指数影响更显著。研究结果可提高对燃爆压裂过程中岩石的破坏模式及其主控因素的认识深度,为燃爆压裂冲击条件设计提供指导。     

铝盐与氢氧化钠反应生成氢氧化铝沉淀的实验探究

通过数字实验对Al2(SO4)3溶液与NaOH反应过程中pH的变化进行探究,得出pH与NaOH溶液的体积(V)之间的变化曲线,从而建立铝盐与NaOH溶液反应时,Al(OH)3沉淀的生成与溶解和NaOH量的变化关系。此研究可以改变人们在Al(OH)3两性认识上存在的误区,对中学化学教学起到积极的作用。     

磁性和非磁性元素掺杂的自旋梯状化合物Sr_(14)(Cu_(0.97)M_(0.03))_(24)O_(41)(M=Zn,Ni,Co)的结构和电输运性质

利用固相反应法制备了Sr14Cu24O41及其系列B位掺杂Sr14(Cu0.97M0.03)24O41(M=Zn,Ni,Co)的样品.X射线衍射分析显示,所有样品均为纯相,晶格常数a与c没有明显的变化;Zn掺杂样品晶格常数b没有明显变化,而Ni,Co掺杂样品晶格常数b分别稍有增加.选区电子衍射研究揭示:磁性元素Ni,Co及非磁性元素Zn掺杂,可能主要替代了Sr14Cu24O41结构中自旋链上的Cu原子,从而影响了自旋链上的dimer排列,破坏电荷有序超结构.电输运测量显示:Zn2+,Ni2+,Co3+离子掺杂样品的电阻率降低,但仍体现半导体行为,所有的掺杂样品都存在一个渡越温度Tρ,当TTρ时,其导电机理是以单空穴热激发导电占主要地位,在TTρ时,配对的局域化空穴的一维变程跳跃导电占主要优势;在相同的掺杂量下,非磁性元素Zn掺杂对电阻率值的影响大于磁性元素Ni,Co掺杂的影响,而磁性元素Ni,Co掺杂对渡越温度Tρ的影响大于非磁性元素Zn掺杂的影响.     

Modulational instability in a layered Kerr medium: theory and experiment

We present the first experimental investigation of modulational instability in a layered Kerr medium. The particularly interesting and appealing feature of our configuration, consisting of alternating glass-air layers, is the piecewise-constant nature of the material properties, which allows a theoretical linear stability analysis leading to a Kronig-Penney equation whose forbidden bands correspond to the modulationally unstable regimes. We find very good quantitative agreement between theoretical, numerical, and experimental diagnostics of the modulational instability. Because of the periodicity in the evolution variable arising from the layered medium, there are multiple instability regions rather than just one as in a uniform medium.     

�����п�ʽ΢��г��ǻ����ϵͳ�о�

介绍了开式微波谐振腔测量系统的工作原理及试验结果,获得了Æ10mm钢球模型在6.65kPa干燥空气中以速度5.44km.s-1飞行时的尾迹电子密度测量结果,并且与国外弹道靶试验数据进行了比较。试验结果表明,该系统能够满足模型尾迹电子密度变化对测量系统响应时间的要求,能很好地反映尾迹电子密度变化细节,电子密度测量范围达到109~1011cm-3。     

Implementation of a multi-scroll novel two-attractor grid chaotic system

This paper proposed a method of generating two attractors in a novel grid multi-scroll chaotic system. Based on a newly generated three-dimensional system, a two-attractor grid multi-scroll attractor system can be generated by adding two triangular waves and a sign function. Some basic dynamical properties, such as equilibrium points, bifurcations, and phase diagrams, were studied. Furthermore, the system was experimentally confirmed by an electronic circuit. The circuit simulation results and numerical simulation results verified the feasibility of this method.     

Modeling of 4H--SiC multi-floating-junction Schottky barrier diode

This paper develops a new and easy to implement analytical model for the specific on-resistance and electric field distribution along the critical path for 4H-SiC multi-floating junction Schottky barrier diode. Considering the charge compensation effects by the multilayer of buried opposite doped regions, it improves the breakdown voltage a lot in comparison with conventional one with the same on-resistance. The forward resistance of the floating junction Schottky barrier diode consists of several components and the electric field can be understood with superposition concept, both are consistent with MEDICI simulation results. Moreover, device parameters are optimized and the analyses show that in comparison with one layer floating junction, multilayer of floating junction layer is an effective way to increase the device performance when specific resistance and the breakdown voltage are traded off. The results show that the specific resistance increases 3.2 mΩ·cm 2 and breakdown voltage increases 422 V with an additional floating junction for the given structure.