Creep deformation and crack growth behavior of a single-crystal nickel-base superalloy

Uniaxial creep deformation and crack growth data are presented on the single-crystal nickel-base superalloy SC16, which is a candidate material for industrial gas turbine applications. All testing was performed at 900 °C. The uniaxial experiments were conducted with the loading direction aligned approximately along the [001] crystallographic axis of the material. Under these conditions, a small primary region followed by mainly tertiary creep was obtained, and failure initiated from cracks at interdendritic pores. The crack growth experiments were performed on single-edge notch tension specimens and compact tension test pieces containing deep side grooves to examine state-of-stress effects. A selection of crystallographic orientations was also examined. Little effect of stress state and orientation was obtained. It has been found that the creep crack growth characteristics of the alloy can be predicted satisfactorily from a model of the accumulation of damage at a crack tip using the creep fracture mechanics parameter C* and assuming plane stress conditions. This article is based on a presentation made at the “High Temperature Fracture Mechanisms in Advanced Materials” symposium, as a part of the 1994 Fall meeting of TMS, October 2-6, 1994, in Rosemont, Illinois, under the auspices of the ASM/SMD Flow and Fracture Committee.     

用于曳引式无机房（MRL）电梯的自驱动轿厢

过去几年中，曳引式无机房（MRL）电梯主宰了欧洲电梯市场，其发展不仅超越了液压电梯，也超越了普通曳引式电梯。     

Enhanced Reduced Pin-Count Test for Full-Scan Design

This paper presents enhanced reduced pin-count test (E-RPCT) for low-cost test. E-RPCT is an extension of traditional RPCT for circuits in which a large number of digital IC pins is multiplexed for scan. The basic concept of E-RPCT is to provide access to the internal scan chains via an IEEE 1149.1 compatible boundary-scan architecture, instead of direct access via the IC pins. The boundary-scan chain performs serial/parallel conversion of test data. E-RPCT also provides I/O wrap to test non-contacted pins. The paper presents E-RPCT for full-scan design, as well as for full-scan core-based design.     

Best packetisation scheme for H.263 Internet video communication

The H.263 codec is an efficient way to stream variable bit-rate video sequences. It is proposed that, for equivalent bandwidth and frame rate, a two-slice packetisation scheme results in superior peak signal-to-noise ratio, rather than the conventional one-slice scheme, and that constant inter-packet gap rather than 'bursty' delivery is preferable.     

A phase II study of interleukin-2 in 49 patients with relapsed or refractory acute leukemia

Two monoclonal antibodies (mAb) within cluster M4 of the myeloid section of the Second International Swine CD Workshop, C4 (No. 144) and PM18-7 (No. 192), showed reactivity with thymocytes and among cells of myelomonocytic origin with mature macrophages but not with monocytes and granulocytes. Both mAb recognize a protein showing two bands of 205 kDa and 130 kDa under both reducing and non-reducing conditions. Although epitope mapping with these mAb could not be performed, this cluster received the SWC9 designation.     

Acute bacterial pneumonia in rats increases alveolar epithelial fluid clearance by a tumor necrosis factor-alpha-dependent mechanism

To study the rate and regulation of alveolar fluid clearance in acute pneumonia, we created a model of Pseudomonas aeruginosa pneumonia in rats. To measure alveolar liquid and protein clearance, we instilled into the airspaces a 5% bovine albumin solution with 1.5 microCi of 125I-human albumin, 24 h after intratracheal instillation of bacteria. The concentration of unlabeled and labeled protein in the distal airspaces over 1 h was used as an index of net alveolar fluid clearance. Since there was histologic evidence of alveolar epithelial injury, several methods were used to measure alveolar fluid clearance, including the use of experiments in rats with blood flow and the use of experiments in rats without blood flow, so that movement across the epithelial barrier would be minimized in the latter group. The results with each method were identical. We found that P. aeruginosa pneumonia increased alveolar liquid clearance over 1 h by 48% in studies with blood flow, and by 43% in rats without blood flow, compared with respective controls (P < 0.05). In both studies, this increase was inhibited with amiloride. However, propranolol had no inhibitory effect, thus ruling out a catecholamine-dependent mechanism to explain the increase in alveolar fluid clearance. An antitumor necrosis factor-alpha neutralizing antibody, instilled into the lung 5 min before bacteria, prevented the increase in alveolar liquid clearance in rats with pneumonia (P < 0.05). Also, TNFalpha (5 microg) instilled in normal rats increased alveolar liquid clearance by 43% over 1 h compared with control rats (P < 0.05). In normal rats instilled with TNFalpha, propranolol had no inhibitory effect. In conclusion, gram-negative pneumonia markedly upregulates net alveolar epithelial fluid clearance, in part by a TNFalpha-dependent mechanism. This finding provides a novel mechanism for the upregulation of alveolar epithelial sodium and fluid transport from the distal airspaces of the lung.