Preparation and adsorption properties of poly(N‐vinylformamide/acrylonitrile) chelating fiber for heavy metal ions

In this article we report a new chelating fiber that was prepared from a hydrolyzate of poly(N‐vinylformamide/acrylonitrile) by a wet‐spinning method. This fiber contains chelating groups, such as amidine groups, amino groups, cyano groups, and amide groups, with high densities. We examined the chelating abilities for several metal ions with this fiber, and present the morphological merit of the fibrous product compared with the globular resin. Based on the research results, it is shown that the fiber has higher binding capacities and better adsorption properties for heavy metal ions than the resin. The pH value of the metal ion solution shows strong influences on the adsorption of the metal ions. The maximum adsorption capacities of the fiber for Cu²⁺, Cr³⁺, Co²⁺, Ni²⁺, and Mn²⁺ are 112.23, 88.11, 141.04, 108.06, and 73.51 mg/g, respectively. In mixed metal ions solution, the fiber adsorbs Cr³⁺, Cu²⁺ and Co²⁺ efficiently. The adsorbed metal ions can be quantitatively eluted by hydrochloric acid. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1378–1386, 2002     

Anti-Oncogenic gem-Dihydroperoxides Induce Apoptosis in Cancer Cells by Trapping Reactive Oxygen Species

Organic gem-dihydroperoxides (DHPs) and their derived peroxides have attracted a great deal of attention as potential anti-cancer agents. However, the precise mechanism of their inhibitory effect on tumors is unknown. To determine the mechanism of the inhibitory effects of DHPs, we examined the effects of DHPs on leukemia K562 cells. As a result, certain DHPs used in this study exhibited growth-inhibitory activity according to a clear structure-activity relationship. The most potent DHP, 12AC3O, induced apoptosis in K562 cells, but not in peripheral blood monocytes (PBMCs) or fibroblast cells. 12AC3O induced apoptosis through the intrinsic mitochondrial pathway and thereafter through the extrinsic pathway. The activity of the former pathway was partly attenuated by a JNK inhibitor. Interestingly, 12AC3O induced apoptosis by trapping a large amount of ROS, leading to an extremely lower intracellular ROS level compared with that in the cells in the steady-state condition. These results suggest that an appropriate level of intracellular ROS was necessary for the maintenance of cancer cell growth. DHPs may have a potential to be a novel anti-cancer agent with minimum adverse effects on normal cells.     

The effect of abrasive grain size on the transition between abrasive and adhesive wear

Experiments were carried out in which SiC abrasives with a grain size range of 3–150 μm were inserted between sliding metals. The metals were pure aluminium, copper, iron, nickel and zinc. The test geometry was a tube end against a flat surface. The effect of grain size can be classified into three regimes. In the first, where abrasive grains are larger than a critical size d_c (about 50 μm), the wear rate is independent of grain size. In the second regime the wear rate decreases as abrasive grains become smaller than d_c to a limit at a transition grain size d_t (about 10 μm). In the third regime the wear rate is high and independent of abrasive grain size. The wear debris consists of large metal flakes with abrasive particles mixed in. Although abrasive particles are present, the wear is primarily adhesive, and the action of the abrasive particles is to promote the removal of metallic wear debris from the contact region.     

Predictors of cardiovascular events in hemodialysis patients after stress myocardial perfusion imaging

Cardiovascular prognosis in patients under normal stress myocardial perfusion images (MPI) is generally excellent. However, this is not true for patients with chronic kidney disease (CKD) treated by hemodialysis. This study evaluated prognostic factors of adverse cardiovascular events in hemodialysis patients in whom stress MPI was performed. Pharmacological stress MPI was performed in 88 hemodialysis patients, and we retrospectively followed‐up for 26 months. Cardiovascular events included cardiac death, nonfatal myocardial infarction, and unstable angina. Cardiovascular events occurred in 16 patients (18%). Univariate Cox regression analysis revealed that peripheral artery disease (PAD) and parameters of stress MPI were significant predictors of cardiovascular events. Multivariate Cox regression analysis revealed that only PAD (hazard ratio = 6.54; P = 0.002), and abnormal stress MPI (hazard ratio = 8.26; P = 0.008) were independent and significant predictors of cardiovascular events. Kaplan–Meier analysis showed better prognosis in patients with normal stress MPI than in patients with abnormal stress MPI (P < 0.001, log–rank test). However, in patients with normal stress MPI, cardiovascular events occurred in 10 of the 76 patients (13%). Among patients with normal stress MPI, Kaplan–Meier analysis showed that patients with no PAD had better prognosis than patients with PAD (P = 0.001, log–rank test). In hemodialysis patients, both PAD and stress MPI were powerful cardiovascular predictors. Normal stress MPI alone cannot guarantee good prognosis in terms of cardiovascular events. Consideration of PAD may improve the predictive value of stress MPI in some patients.     

Current density redistribution from no current crowding to current crowding in Pb-free solder joints with an extremely thick Cu layer

In order to remove the effect of current crowding on electromigration, thick Cu under-bump metallization has been widely adopted in the electronics industry. Three-dimensional (3-D) integrated circuits, using through Si via Cu column interconnects, is being developed, and it seems that current crowding may not be a reliability issue. However, statistical experiments and 3-D finite element simulation indicate that there is a transition from no current crowding to current crowding, caused by void growth at the cathode. An analysis of the electromigration-induced failure mechanism in solder joints having a very thick Cu layer is presented. It is a unique failure mechanism, different from that in flip chip technology. Moreover, the study of marker displacement shows two different stages of drift velocity, which clearly demonstrates the back-stress effect and the development of compressive stress.     

Wear degradation of long-term in vivo exposed alumina-on-alumina hip joints: linking nanometer-scale phenomena to macroscopic joint design

The wear behavior of alumina femoral heads was examined at follow-up periods between 7.7 and 10.7 years. Four head retrievals of the same size (28 mm in diameter) were divided into two groups with different design characteristics. Systematically using scanning electron and atomic force microscopy procedures, wear characteristics could be classified on the entire heads according to five zones with increasing degrees of wear damage (Grade 1–5), in addition to one zone of stripe wear (Grade SW). The stripe wear zone showed quite different topographical features as compared to frictionally worn zones. Furthermore, hip implants designed with different clearances are shown to lead to different wear patterns on the femoral head surface, the smaller the clearance the wider the worn surface area. Cathodoluminescence piezo-spectroscopy provided information about the residual stress state in surfaces worn to different degrees and helped clarifying the wear mechanisms on the microscopic scale.     

Low-temperature polysilicon thin-film transistor driving withintegrated driver for high-resolution light emitting polymerdisplay

A high-resolution low-temperature polysilicon thin-film transistor driven light emitting polymer display (LT p-Si TFT LEPD) with integrated drivers has been developed. We adopted conductance control of the TFT and optimized design and voltage in order to achieve good gray scale and simple pixel circuit. A p-channel TFT is used in order to guarantee reliability in dc bias. An inter-layer reduces parasitic capacitance of bus lines. Because of the combination of the LT p-Si TFT and LEP, the display is thin, compact, and lightweight, as well as having low power consumption, wide viewing angle, and fast response     

STATCOM using the new concept of an inverter system with controlled gradational voltage

This paper presents the STATCOM using the new concept of an inverter system which consists of three inverter units connected in series, and each inverter unit generates a different input voltage such as V_C, 2V_C, 4V_C. This inverter system can output a high‐quality voltage by a low‐frequency switching operation. Thus, it can combine low loss and high quality. In this paper, we show the technique to apply STATCOM which uses the inverter system, and examination results. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(4): 58–65, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ).DOI 10.1002/eej.20823     

Applied analysis and identification of ancient lacquer based on pyrolysis‐gas chromatography/mass spectrometry

Three lacquer samples taken from a “four‐eared” pottery container, which was designated an important National Cultural Property of Japan excavated in 16–17th century ruins of Kyoto City, were analyzed by pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS) and infrared (IR) spectroscopy to determine the source of the lacquer. It is an unexpected result that the lacquer in this pottery container is actually used by Melanorrhoea usitata. Alkylbenzene and alkenylbenzene as cleavage pieces of undecylbenzene (MW = 232 g/mol) and undecenylbenzene (MW = 230 g/mol), which are products of the pyrolysis of thitsiol, were detected in all three samples. Moreover, ω‐phenylalkylcatechols and ω‐phenylalkylphenols, which are the specific components of M. usitata, were also detected by Py‐GC/MS, suggesting that lacquer sap of M. usitata was used by the Japanese people in the 16–17th centuries. In addition, Japanese lacquer culture and the advantages of the Py‐GC/MS method for lacquer analysis are discussed in detail. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010