合金粉末的种类及成形压力对烧结低合金钢弹性模量与泊松比的影响

研究了在相同的烧结与热处理条件下,部分合金化粉末及预合金化粉末的不同合金成分与成形压力对低合金钢弹性模量及泊松比的影响.弹性模量及泊松比的值主要与孔隙度相关,孔隙度通过成形压力控制,而受合金粉末的种类的影响不大.弹性模量及泊松比与孔隙度的关系为E＝E0(1-kE·P)2与v＝0.034·(1-kv·P)2 0.267.式中E0是P＝0时的E值,而kE与kv是实验系数,取决于粉末的种类与烧结温度.     

PEX12, the pathogenic gene of group III Zellweger syndrome: cDNA cloning by functional complementation on a CHO cell mutant, patient analysis, and characterization of PEX12p

Rat PEX12 cDNA was isolated by functional complementation of peroxisome deficiency of a mutant CHO cell line, ZP109 (K. Okumoto, A. Bogaki, K. Tateishi, T. Tsukamoto, T. Osumi, N. Shimozawa, Y. Suzuki, T. Orii, and Y. Fujiki, Exp. Cell Res. 233:11-20, 1997), using a transient transfection assay and an ectopic, readily visible marker, green fluorescent protein. This cDNA encodes a 359-amino-acid membrane protein of peroxisomes with two transmembrane segments and a cysteine-rich zinc finger, the RING motif. A stable transformant of ZP109 with the PEX12 was morphologically and biochemically restored for peroxisome biogenesis. Pex12p was shown by expression of bona fide as well as epitope-tagged Pex12p to expose both N- and C-terminal regions to the cytosol. Fibroblasts derived from patients with the peroxisome deficiency Zellweger syndrome of complementation group III (CG-III) were also complemented for peroxisome biogenesis with PEX12. Two unrelated patients of this group manifesting peroxisome deficiency disorders possessed homozygous, inactivating PEX12 mutations: in one, Arg180Thr by one point mutation, and in the other, deletion of two nucleotides in codons for 291Asn and 292Ser, creating an apparently unchanged codon for Asn and a codon 292 for termination. These results indicate that the gene encoding peroxisome assembly factor Pex12p is a pathogenic gene of CG-III peroxisome deficiency. Moreover, truncation and site mutation studies, including patient PEX12 analysis, demonstrated that the cytoplasmically oriented N- and C-terminal parts of Pex12p are essential for biological function.     

Sound-induced activation of auditory cortices in cochlear implant users with post- and prelingual deafness demonstrated by positron emission tomography

Lactoferrin has been for the first time purified from the porcine cauda epididymal fluid as a 70 kDa protein. Both Western and Northern blot analyses show that lactoferrin is synthesized in the regions from the distal caput to the cauda epididymis and secreted into the luminal fluid. Lactoferrin is first secreted as a 75 kDa glycoprotein and its carbohydrate moieties are gradually digested to form 70 kDa protein in the cauda epididymis. Lactoferrin has already bound to the surface of the epididymal sperm because the anti-lactoferrin antiserum induces the mature sperm tail-to-tail agglutination. These results strongly suggest new physiological functions of lactoferrin on the sperm maturation in the epididymis.     

Corticospinal direct response to transcranial magnetic stimulation in humans

The corticospinal motor evoked potential (MEP) response to transcranial magnetic stimulation of the motor cortex was investigated in comparison with the direct (D) response to electrical stimulation of the exposed motor cortex from the spinal epidural space in 7 neurologically normal patients during brain tumor surgery. The D response during operation was obtained by transcranial magnetic stimulation of the scalp over the areas of the cerebral motor cortex, the hand or arm areas. The magnetic induced D response showed a conduction velocity of 50.5-72.7 m/sec and was resistant to anesthesia and unaffected by muscle relaxants and tolerant to high frequency (500 Hz) paired magnetic stimulus, and the latencies of magnetic MEPs corresponded to those with direct electrical stimulation. Thus, recordings of the D response by transcranial magnetic stimulation are useful for not only identifying the location of the motor cortex during intracranial surgery but also for non-invasive recording of pyramidal tract activity during extracranial surgery under general anesthesia.     

直喷汽油(DIG)汽车发动机无声链条系统用温压-高温烧结粉末冶金链轮的开发

作者们以前报导过非直喷汽油 (一般MPI汽油 )发动机滚子链条系统用温压 -常规温度 ( 114 0℃ )烧结的粉末冶金链轮。在这个新开发的项目中 ,研究了几种温压 -高温烧结的粉末冶金钢的力学性能。为测定这些材料的耐磨性 ,用虚拟发动机进行了磨耗试验。最终开发出了可承受严酷磨耗条件的DIG发动机无声链条系统的链轮。使用的基础粉末是混合粉 (DistaloyDC1)。其含 2 %Ni(质量分数 ) ,Ni粉是通过扩散粘结在Fe - 1 5 %Mo(质量分数 )粉末颗粒上的 ,温压是在 130℃下 ,用这种粉末、阴模及模具进行的。烧结温度为 1190℃。链轮还进行了热处理     

Conduction pathways of motor evoked potentials following transcranial magnetic stimulation: a rodent study using a "figure-8" coil

We have examined the conduction pathways of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation, and their correlation with locomotor function in rats. MEPs were concomitantly recorded from the spinal cord (sMEPs) and the limb muscles (mMEPs) before and after various spinal tract ablations. Motor function was also examined using an inclined plane test. sMEPs were composed of four negative peaks (N1-N4) and mMEPs of high-voltage, biphasic waves. Ventral funiculus transection reduced the N1-N3 peaks and abolished mMEPs. Contrarily, dorsal funiculus transection including the pyramidal tract did not alter these MEPs. Motor performance on an inclined plane was worse after ventral funiculus transection than after other transections. These findings indicate that, in rats, the N1-N3 peaks of magnetic sMEPs conduct ventral funiculus activity, and that magnetic mMEPs mainly reflect extrapyramidal activities and are correlated with locomotor function.     

Biliary and pancreatic excretion of etoposide

Although biliary excretion of Etoposide is thought to be one of the main excretory routes, less investigation has been performed in human because of the clinical difficulties of bile collection. In the present study, the biliary and pancreatic excretion of Etoposide was examined through the hepaticus- or pancreaticus drainage in two pancreatoduodenectomized patients. The drug (95 mg) was infused for 30 min. Blood, bile and pancreatic juice were taken consecutively during and after infusion. Etoposide in the samples was measured as an unchanged type by HPLC. Etoposide was detected in the bile at the same level or more of the blood, their correlation being significant during the observation period. Recovery of the unchanged drug from the hepatic bile in the present series was 2.7-3.0% during the period of 3.5 hrs. And total recovery was estimated as 3.5-4.0% from AUC of the further extended concentration curve. Pancreatic excretion of Etoposide was minimum, its ratio with blood concentration being 2-3%. Recovery for 3.5 hrs. was less than 0.02%. From the data obtained, the biliary excretion of Etoposide was discussed together with its metabolites.     

Mesoporous Silica Sorbents Impregnated with Blends of Tetraethylenepentamine and Alkanolamine for CO2 Separation

Mesocellular silica foam (MSU-F) supports were functionalized via wet impregnation with various amine and alcohol compounds for use as high-capacity adsorbents for CO₂ separation. The effect of the amino, hydroxyl, and ether functional groups in the impregnating mixture on the CO₂ adsorption capacity was investigated. Chemical adsorption was controlled by the composition of the compounds, and the blending effect on the adsorption performance was dependent on the temperature. MSU-F (30 wt.%) impregnated with a mixture of tetraethylenepentamine (40 wt.%) and aminoethylethanolamine (30 wt.%) showed a high adsorption capacity of 5.4 mmol/g at 333 K for 15 kPa CO₂.