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61.
There is a small, but significant, increase in frequency during hypercapnia in vagotomized, anesthetized animals, indicating involvement of an extravagal mechanism in the response. The intent of this study was to determine the source of this second mechanism regulating frequency during hypercapnia. Experiments were performed on 22 vagotomized, anesthetized (Dial) cats. Frequency (f), inspiratory time (ti) and expiratory time (te) responses to CO2 were monitored before and after sectioning of afferent nerves from the carotid bodies (carotid sinus nerve section), chest wall (dorsal rhizotomies, T1-T12) and diaphragm (dorsal rhizotomies. C4-C7). Most vagotomized animals responded to 6% CO2 with an increased frequency, decreased ti and no consistent change in te. The responses to CO2 were essentially unaltered following chest wall and diaphragm deafferentation. Sodium cyanide stimulation of the carotid bodies produced similar respiratory pattern changes as CO2; furthermore, the f and ti changes with CO2 were still present following carotid body deafferentiation. The results of this study suggest that: (1) afferents from chest wall and diaphragm mechanoreceptors are not responsible for the vagal-like effects on ti and f during hypercapnia, (2) afferents from lung mechanoreceptors, via the vagus nerves, are the only inputs from respiratory mechanoreceptors causing an increased f during hypercapnia, (3) the extravagal mechanism responsible for the decreased ti and increased f during hypercapnia is inherent to the medullary-pontine rhythm generator, and (4) input from the chemoreceptors can elicit the response.  相似文献   
62.
The present study describes the effect of Peucedanum japonicum Thunb (PJT) intake on the expression of obesity-related genes in mice fed a high-fat diet. To explore the mechanism underlying the effect of PJT, This study focused on the expression of genes, especially those related to obesity and metabolism syndrome, in the liver and adipose tissues. In agreement with our previous observations, intake of 10 % PJT for 4 weeks significantly reduced serum triglyceride (TG), leptin, abdominal fat, and adipocyte size. PJT also significantly increased fecal excretion of TG, decreased that of bile acid, and tended to increase the fecal excretion of total cholesterol. Microarray analysis was used to monitor changes in 324 metabolic syndrome-related genes in the liver. Statistically significant upregulation of PPP1R10, RORC, and PBEF1 genes and downregulation of DUSP1, INSIG2, and SERPINA12 genes were noted and confirmed by real-time RT-PCR. These changes were indicative of increased fatty acid oxidation in the maintenance of lipid homeostasis and insulin sensitivity in the livers of PJT-fed mice. PJT increased the expression of PPARγ, FXRα, DGAT1, and ATGL genes, suggesting an enhancement of adipocyte differentiation and normalization of functionality of adipose tissue.  相似文献   
63.
Manabu Oku  李鑫 《世界钢铁》2011,11(5):10-16
为了减轻空气污染和缓解全球变暖,各个国家均出台了尾气排放标准,且限制标准越来越严格。在此背景下,多种技术已被应用以满足相关要求,如提高燃油燃烧率、催化效率,降低排气管热容量等。而这一系列措施均会导致汽车尾气的最高温度上升。近些年,汽车排气系统零件主要用铁素体不锈钢制作,因为铁素体不锈钢的热膨胀系数小,耐循环氧化和耐高温疲劳性能均优于奥氏体不锈钢。介绍了日新制钢新研发的汽车排气系统用耐热不锈钢,以及该钢种的研发现状和发展趋势。Nb、Mo、Cu在700℃时的固溶强化和析出强化对提高铁素体不锈钢的高温强度非常有效,而添加Nb、Mo、W主要是在900℃时起到固溶强化作用。Cr,Si和Mn可降低铁素体不锈钢(含14%Cr)在大气中950℃保温200h的氧化程度。特别是添加0.8%及以上的Mn可有效提高氧化皮的附着力。事实证明,日新制钢开发的NSSHR-1(14Cr-1Mn-0.9Si-Nb)和NSSHR-2(10Cr-0.9Si-Nb-Ti)铁素体不锈钢与441和439不锈钢相比,具有更高的耐热性和成形性。  相似文献   
64.
In this study, we constructed prediction models by metabolic fingerprinting of fresh green tea leaves using Fourier transform near-infrared (FT-NIR) spectroscopy and partial least squares (PLS) regression analysis to objectively optimize of the steaming process conditions in green tea manufacture. The steaming process is the most important step for manufacturing high quality green tea products. However, the parameter setting of the steamer is currently determined subjectively by the manufacturer. Therefore, a simple and robust system that can be used to objectively set the steaming process parameters is necessary. We focused on FT-NIR spectroscopy because of its simple operation, quick measurement, and low running costs. After removal of noise in the spectral data by principal component analysis (PCA), PLS regression analysis was performed using spectral information as independent variables, and the steaming parameters set by experienced manufacturers as dependent variables. The prediction models were successfully constructed with satisfactory accuracy. Moreover, the results of the demonstrated experiment suggested that the green tea steaming process parameters could be predicted on a larger manufacturing scale. This technique will contribute to improvement of the quality and productivity of green tea because it can objectively optimize the complicated green tea steaming process and will be suitable for practical use in green tea manufacture.  相似文献   
65.
Peutz-Jeghers syndrome (PJS) is an autosomal dominant disease characterized by mucocutaneous pigmentation and hamartomatous polyps. There is an increased risk of benign and malignant tumors in the gastrointestinal tract and in extraintestinal tissues. One PJS locus has been mapped to chromosome 19p13.3; a second locus is suspected on chromosome 19q13.4 in a minority of families. The PJS gene on 19p13.3 has recently been cloned, and it encodes the serine/threonine kinase LKB1. The gene, which is ubiquitously expressed, is composed of 10 exons spanning 23 kb. Several LKB1 mutations have been reported in heterozygosity in PJS patients. In this study, we screened for LKB1 mutations in nine PJS families of American, Spanish, Portuguese, French, Turkish, and Indian origin and detected seven novel mutations. These included two frameshift mutations, one four-amino-acid deletion, two amino-acid substitutions, and two splicing errors. Expression of mutant LKB1 proteins (K78I, D176N, W308C, and L67P) and assessment of their autophosphorylation activity revealed a loss of the kinase activity in all of these mutants. These results provide direct evidence that the elimination of the kinase activity of LKB1 is probably responsible for the development of the PJS phenotypes. In two Indian families, we failed to detect any LKB1 mutation; in one of these families, we previously had detected linkage to markers on 19q13.3-4, which suggests locus heterogeneity of PJS. The elucidation of the molecular etiology of PJS and the positional cloning of the second potential PJS gene will further elucidate the involvement of kinases/phosphatases in the development of cancer-predisposing syndromes.  相似文献   
66.
A novel configuration, which can reduce the number of gates in a wavelength division multiplexing (WDM) channel selector, is proposed. A monolithically integrated 64-channel selector is realised with only 16 optical gates. Selecting operation for all 64 channels was confirmed and zero insertion loss was achieved for almost all channels  相似文献   
67.
A Sagnac interferometer integrated with a parallel-amplifier structure (SIPAS) is proposed for filter-free all-optical wavelength conversion. A Mach-Zehnder interferometer with a semiconductor optical amplifier in each arm is monolithically integrated with a Sagnac interferometer. Clear eye opening and low power penalty of 0.9 dB were achieved at a bit rate of 10 Gbit/s using the fabricated SIPAS.  相似文献   
68.
In order to explore a possibility of forming an intermediate semiconductor layer with low Schottky barrier by the conventional deposition and annealing technique, the electrical properties of Cd and Te-based contacts on the nitrogendoped ZnSe substrates have been investigated. Cd in the Cd/W contact reacted with the ZnSe substrate after annealing at temperatures above 250°C and formed epitaxial Ccx}Zn1−xSe layers, leading to reduction of the “turn-on” voltage (VT) from about 11 to 6 V (here, a slash “/” between Cd and W means the deposition sequence). The reduction of the Vn} value by annealing at elevated temperatures was also observed for the Bi-Cd/W and In-Cd/W contacts. The average Cd composition (x) in the Cdn}Zn1−xSe layers was measured to be larger than 0.9, which agreed with the values estimated from the calculated Cd-Zn-Se phase diagrams. The ohmic behavior was strongly influenced by the thickness of the CdxZn1−xSe layer, the density of misfit dislocations formed at the interface between the Cdx Zn1−x Se and the ZnSe, and/or the total area of the Cd Zn. Se layers covering the ZnSe surface. The present result suggests that formation of the large-areal CcxZn1−xSe layers with thin thickness is crucial to achieve further reduction of the VT value by the conventional deposition and annealing technique. Also, the VT reduction was not obtained for the Te/W contact even after annealing at temperatures close to 300°C, which was explained to be due to absence of ternary ZnSe1−xTen intermediate layers.  相似文献   
69.
Fracture origins of single-mode optical fibers that were produced by the CIP hybridized process consisting of overcladding a VAD-derived core rod with silica glass made from commercial silica powder were studied. It was found that there were many inclusions that caused failure of the fiber at the screening test. To identify the inclusions, the EPMA technique was successfully used and new internal defects such as a Cr, a Cr-Fe, and a Zr inclusions were found. By investigating the manufacturing process precisely, stainless steel particles and Cr2 O3 particles in the silica powder were found to become origins of the fractures. Further, the removal of Cr2O3 particles by the reaction with chlorine gas at high temperature was studied, and its dependence on the reaction temperature and on the chlorine content was clarified. It was also suggested that the initial particle size of a Cr2O3 particle was an important factor for its elimination. The results obtained by this study should be used to remove both the Cr and the Cr-Fe inclusions  相似文献   
70.
For passive targeting of liposomes to tumor tissues, we earlier developed reticuloendothelial system (RES)-avoiding liposomes modified with a uronic acid derivative, palmityl-D-glucuronide (PGlcUA). In the present study, we encapsulated technetium-99m (99mTc)-diethylenetriaminepentaacetic acid (DTPA) in PGlcUA-liposomes (dipalmitoylphosphatidylcholine:cholesterol:PGlcUA = 40:40:20 as a molar ratio) and studied the biodistribution of the liposomes in tumor-bearing mice. 99mTc-DTPA encapsulated in liposomes effectively accumulated in tumor tissues after intravenous administration. Corresponding to these results, tumor was strongly imaged by a gamma-camera when 99mTc-DTPA-encapsulated PGlcUA-liposomes were used.  相似文献   
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