蒸汽冷凝水回收

分析了降温回收、等温回收、升温回收3种方式的原理及设计要点，指出了各种方式的适用场合。着重介绍了改进的等温回收方式。     

Endotoxins affect diverse biological activity of chitosans in matters of hemocompatibility and cytocompatibility

Chitosan is used in several pharmaceutical and medical applications, owing to its good cytocompatibility and hemocompatibility. However, there are conflicting reports regarding the biological activities of chitosan with some studies reporting anti-inflammatory properties while others report pro-inflammatory properties. In this regards we analyzed the endotoxin content in five different chitosans and examined these chitosans with their different deacetylation degrees for their hemocompatibility and cytocompatibility. Therefore, we incubated primary human endothelial cells or whole blood with different chitosan concentrations and studied the protein and mRNA expression of different inflammatory markers or cytokines. Our data indicate a correlation of the endotoxin content and cytokine up-regulation in whole blood for Poly-Morpho-Nuclear (PMN)-Elastase, soluble terminal complement complex SC5b-9, complement component C5/C5a, granulocyte colony-stimulating factor, Interleukin-8 (IL), IL-10, IL-13, IL-17E, Il-32α and monocyte chemotactic protein-1. In contrast, the incubation of low endotoxin containing chitosans with primary endothelial cells resulted in increased expression of E-selectin, intercellular adhesion molecule-1, vascular cell adhesion protein-1, IL-1β, IL-6 and IL-8 in endothelial cells. We suggest that the endotoxin content in chitosan plays a major role in the biological activity of chitosan. Therefore, we strongly recommend analysis of the endotoxin concentration in chitosan, before further determining if it has pro- or anti-inflammatory properties or if it is applicable for pharmaceutical and medical fields.     

铝基复合材料超声波钎焊陶瓷颗粒增强接头强度机理(英文)

对含有55%SiC高体积分数的铝基复合材料以Zn基合金作为钎料层进行超声波辅助钎焊。在420℃和475℃钎焊温度下,形成分别含有7%和35%SiC体积分数的连接接头。两种接头的微观拉伸原位分析结果显示,它们不但具有不同的微观结构,而且具有不同的裂纹生长传播机制,从而具有不同的力学性能。含有35%SiC的接头剪切强度达到244MPa,比含有7%SiC的高出84.7%。其原因是接头中SiC颗粒可以抑制裂纹的产生及传播,Al基固溶体也可抑制裂纹生长。因此,在合适的超声波钎焊温度下,SiC颗粒和Al元素更多地扩散至接头区,使得接头剪切强度增高。     

Evaluation of disease status with sensitive measures of growth hormone secretion in 60 postoperative patients with acromegaly

Traditionally, suppression of GH measured by polyclonal RIA to less than 2.0 microg/L after oral glucose was accepted as evidence of remission after transsphenoidal surgery for acromegaly. Recently, with newer, more sensitive GH assays, a cut-off of less than 1.0 microg/L has been suggested. With the development of accurate insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) assays, additional tools are now available for assessing postoperative GH secretion. There has, however, never been a systematic comparison of sensitive GH, IGF-I, and IGFBP-3 assays in defining disease status in a large cohort of postoperative patients with acromegaly. Therefore, we evaluated how the use of modern assays impacts on our assessment of disease activity in these patients. Sixty postoperative subjects with acromegaly and 25 age-matched healthy subjects were evaluated with nadir GH levels after 100 g oral glucose as well as baseline IGF-I and IGFBP-3 levels. GH was assayed by polyclonal RIA, sensitive immunoradiometric assay (IRMA), and highly sensitive enzyme-linked immunosorbent assay. The mean nadir GH determined by IRMA was 0.09 +/- 0.004 microg/L in the healthy subjects, with the upper limit of the normal nadir being 0.14 microg/L (mean + 2 SD). Subjects with acromegaly were divided into those with active disease (n = 22), defined by elevated IGF-I levels, and those in remission (n = 38), defined by normal IGF-I levels. GH determined by IRMA failed to suppress into the normal range defined by our healthy subjects in all patients with active disease; nadir GH determined by IRMA ranged from 0.33-5.0 microg/L in this group. In 50% of the active group, nadir GH levels determined by IRMA were less than 1.0 microg/L, a GH nadir previously considered normal by strict criteria. When nadir GH levels in the subjects with active disease were measured by polyclonal RIA, there was overlap with the range of RIA values in the healthy subjects. Thus, the IRMA was superior to the RIA in that the overlap between these two groups was eliminated. Subjects with acromegaly in remission included those with normal GH suppression (n = 23; mean nadir GH by IRMA, 0.10 +/- 0.006 microg/L) and others with abnormal GH suppression by IRMA (n = 15; mean nadir GH by IRMA, 0.35 +/- 0.07 microg/L). The latter group may have persistent GH dysregulation detected by the sensitive IRMA. GH levels measured by enzyme-linked immunosorbent assay confirmed the IRMA results. IGFBP-3 levels were significantly higher in subjects with active acromegaly (4940 +/- 301 microg/L) vs. those in healthy subjects (2887 +/- 153 microg/L; P < 0.0001) and those in the subjects in remission (2966 microg/L; P < 0.0001). IGFBP-3 levels correlated overall with IGF-I levels (r = 0.765; P < 0.0001), but IGFBP-3 levels were not predictive of disease status because 32% of the subjects with active acromegaly had normal IGFBP-3 levels. In addition, failure of GH to suppress adequately was not associated with a higher IGFBP-3 level among the subjects in remission. These data indicate that the IRMA is superior to the RIA in distinguishing between patients with active disease (defined by elevated IGF-I levels) and healthy subjects. We also show that GH levels after oral glucose measured with highly sensitive GH assays can be much lower in subjects with active disease than previously believed; values less than 1.0 microg/L may be found in up to 50% of patients. In addition, in 39% of patients in apparent remission with normal IGF-I levels, GH determined by highly sensitive assays fails to suppress normally; it remains to be determined whether these patients are at higher risk for recurrence of active disease.     

Numerical and experimental analysis of aerostatic thrust bearings with porous restrictors

The finite element method is used to predict the performance of aerostatic thrust bearings with a complete porous surface. Results obtained by a 1D and 3D source flow model derived from D’Arcy’s law are compared for rectangular porous bearings having an infinite width. It turns out that the 1D source flow model is adequate for practical design parameters. For a circular aerostatic porous thrust bearing results calculated with several mathematical models for the source flow and slip flow are compared with experimental results. A relatively simple model incorporating unflatness and deformation of the bearing surface correlates well with the experimentally determined bearing performance.     

New aspects and mechanism of kink effect in InAlAs/InGaAs/InPinverted HFETs

The kink effect in InAlAs/InGaAs/InP composite channel heterojunction field effect transistors (HFETs) was investigated as a function of temperature and optical excitation. Drain source and gate current measurements show that above 325 K the kink effect disappears while the impact ionization process is still present. The kink at low temperatures is suppressed by illumination with photons of energy above 1 eV. These results prove that this parasitic effect is mainly related to the presence of traps in the top layers     

Real Option—A New Approachin the Evaluation of TelecomInvest ment Projects

1IntroductionNowadays ,telecomindustry is facing many uncer-tainties ,because of which some carefully designed planshave to be completely renewed.It s a great challenge tous to adapt our work to the changing circumstances anddi minish the loss brought by various uncertainties .Option,by enabling the investor to control uncertainrisks at the expense of some cost can effectively li mitlosses and indefinitely increase the potential to grow.This is the most attractive feature of modern option,andf…     

R_2Fe_(17-x)M_x金属间化合物磁性质的分子场论分析

本文用两格点分子场论（ＭＦＴ）分析了Ｒ２Ｆｅ１７－ｘＭｘ金属间化合物磁性质与温度的关系。得出了ＨＲ（Ｔ）、ＨＦＢ（Ｔ）和ＨＲ（Ｔ）／ＭＦＢ（Ｔ）与温度的关系曲线和分子场系数ｎＲＲ、ｎＲＦ和ｎＦＦ。表明此理论能精确地描述这些化合物磁化的温度关系     

PbS与PbO及硅酸铅反应的动力学和PbO的活度

为了阐明QSL法直接炼Pb的化学反应动力学,研究PbS与PbO及xPbO·SiO_2的交互作用是具有实际意义的。为了避免高温造成PbS和PbO的挥发损失,在较低温度下研究该体系的交互反应动力学,对探索火法炼Pb新工艺具有一定价值。试料是分析纯PbO,PbS和合成的纯xPbO·SiO_2,试料粒度均为100—120 mesh,在配比试样中以PbO:PbS=2:1作基础并混匀,以便保证按化学计量反应产生SO_2。装有试料的刚玉坩埚在密封竖直刚玉管底部低温区用Ar气保护升温加热,待达到预期温度后,坩埚由密封系统中的活动撑杆推到高温区并同时用Ar气载流使产生的SO_2连续为碘量法所测