Interpenetrating polymer networks based on poly(chloroprene) and poly(carbonate-urethane)

Simultaneous interpenetrating polymer networks (SIN's) of poly(chloroprene) (CR) and poly(carbonate-urethane) (PCU) were prepared and characterized. The effect of composition on the phase morphology of full IPN's of CR/PCU has been studied by DSC and SEM. A single phase morphology of IPN's has achieved when the content of CR component is below 50 wt %. The microphase separation of the component networks in the IPN's occurred in samples whose weight percentage of the CR component was 50% and higher. © 1993 John Wiley & Sons, Inc.     

Multi-element determination in cancellous bone of human femoral head by PIXE

Proton Induced X-ray Emission (PIXE) method is used for the determination of elemental concentrations in cancellous bone of human femoral head from five autopsies and seven patients with femoral neck broken. The specimen preparation and experimental procedure are described in detail. Using the t test, the results show that the concentrations of P, Ca, Fe, Cu, Sr in control group are higher than those in patient group, but the concentrations of S, K, Zn, Mn are not significantly different. The physiological functions of metallic elements in human bone are also discussed.     

Self-cleaning and Oil/Water Separation of 3D Network Super-hydrophobic Bead-like Fluorinated Silica Pellets/Poly(aryl ether ketone) Composite Membrane Fabricated via a Facile One-step Electrospinning

Novel super-hydrophobic fluorinated silica pellets/poly(aryl ether ketone) composite membranes with controllable structure have been prepared through incorporating poly(aryl ether ketone)s with (3-trifluoromethyl)-phenyl side groups and fluorinated silica pellets(F-SiO₂) by a facile one-step electrospinning. Under the condition of adding 50%(mass fraction) F-SiO₂ in the composite membrane, the water contact angle(WCA) reached its maximum (157°±4.3°). The controllable micro/nano-structures grown on the electrospun fibers could be regulated by the F-SiO₂ loading, which was illustrated by scanning electron microscopy(SEM). Moreover, these super-hydrophobic membranes also demonstrated excellent durability, anti-fouling property and oil-water separation ability after 200 h of water flushing. These promising PAEK composite membranes with controllable structure have the potential values in large-scale application of filtration, oil-water separation and antifouling.     

异戊橡胶中填料的絮凝及其对性能的影响

针对硫化过程对异戊橡胶中的填料絮凝及其性能的影响等问题, 通过改变硫化温度和硫化时间, 对比研究了炭黑、 白炭黑、 炭黑/白炭黑混合填料体系中的填料絮凝过程, 比较其动、 静态性能等的变化. 为了分析交联网络在填料絮凝过程中的贡献, 对比了工艺相同的含硫与不含硫胶料在不同温度和时间下的絮凝过程. 在含硫体系中, 佩恩效应主要来自于填料网络和橡胶网络的贡献; 而在不含硫体系中, 佩恩效应主要来自于填料网络的贡献. 研究结果表明, 橡胶网络的形成在一定程度上限制了填料的絮凝, 因此, 随温度升高, 含硫体系的佩恩效应减小, 而无硫体系的佩恩效应逐渐增加或先减小后增加. 随时间延长, 含硫胶料和无硫胶料的佩恩效应均增加, 但机制有所不同. 其中含硫胶料主要来自于交联网络的形成, 而无硫胶料主要来自于填料的絮凝. 絮凝动力学研究表明, 快速絮凝发生在较短的时间范围内, 在长时间范围内絮凝开始变慢但并不会停止, 且在较低温度(60 ℃)下絮凝仍会发生. 此外, 高温和长时间热处理导致材料的拉伸性能出现下降, 但动态疲劳性能有所增强.     

应用同步辐射XRF分析胎毛中铅含量

通过同步辐射微束XRF分析了9名婴儿头发中的铅含量,结果表明,该法可了解胎儿在孕育期内体内铅含量的变化情况,甚至胎儿体内每天的铅含量的变化。通过分析铅在胎毛中含量的变化曲线,可以追踪孕妇在某段时期铅的接触史。     

Carbon-coated hollow CoO microporous nanospheres synthesized by CoF<Subscript>2</Subscript> as the intermediates as anode materials for lithium-ion batteries

Uniformly carbon-coated hollow CoO microporous nanospheres have been successfully synthesized by the facile hydrothermal method using CoF₂ as the intermediates and glucose as the carbon source. The whole synthesis process can avoid using the toxic surfactant additives and tedious post-processing. The glucose-derived carbon not only suppresses the aggregation of CoO nanoparticles, but also plays an important role on the stabilization of hollow CoO microporous nanosphere structure. The specific structure can largely improve the electronic conductivity and accommodate the volume change of CoO electrode in the electrochemical processes. When used as anode materials of lithium ion batteries, the hollow CoO/C microporous composites exhibit exceptionally high-rate performances, high-specific capacity, and improved cycle performances. This study may provide a new approach for the synthesis of carbon-coated hollow microporous architecture electrode for high-performance batteries.     

Dependence of transient photovoltage characteristics on bias light intensity for HgCdTe-based photovoltaic infrared detector pixel arrays

In this paper, experimental investigation of the photovoltaic effect of metal/semiconductor (M/S) interface in HgCdTe pixel arrays are reported. The transient photovoltaic (TPV) response was measured by using a pulsed laser under illumination of steady bias light. A tendency of polarity inversion from peak-to-valley of TPV was observed with increasing bias light intensity. Model for photovoltage transformation was proposed, and proved by comparing the response behavior before and after removing the aperture for the TPV measurements. The Schottky barrier junction of M/S interface is the key factor for the polarity reversal at different bias light intensity. The results provide an effective method to evaluate the electrode quality of the photodetector directly.     

Influence of trap filling and junction capacitance charging on photovoltage transients in HgCdTe-based infrared photodiode

Open circuit transient photovoltage (TPV) decay measurements have been carried out on HgCdTe-based infrared photodiode at different bias-light power illumination. By employing a picosecond pulsed laser excitation with wavelength of \(4.5\,\upmu \hbox {m}\) on steady background illumination, the TPV decay varying behavior has been observed. The effect of junction capacitance and carrier traps on TPV decay can be decreased to the minimum saturation values by increasing the bias illumination level. The study indicates the TPV decay time constants are dominated by the discharging of junction capacitance, trap emission and photocarrier recombination. The minority carrier lifetime are affected by the carrier injection level.