Study on heat transfer characteristics of reservoir embedded loop heat pipe (1st report,Influence of evaporator orientation against gravity and charged liquid weight on heat transfer characteristics)

High‐powered satellites need larger heat rejection areas. A deployable radiator is one of the key technologies for a high‐powered satellite bus. A Reservoir Embedded Loop Heat Pipe (RELHP) is a two‐phase heat transfer device that constitutes a deployable radiator. RELHP has an evaporator core which is used as a liquid reservoir to enhance operational reliability. This paper presents the heat transport characteristics of a RELHP under changing evaporator orientation against gravity and charged ammonia weight by experiment and calculation. Liquid slug position in the reservoir has a great influence on heat transport characteristics, caused by changing heat transfer coefficients between returned liquid into the evaporator and vapor in the reservoir. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(3): 143– 157, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20150     

Dynamical Transition of 4He Crystallization in a Very High Porosity Aerogel

Crystallization of ⁴He in aerogels of 90 and 96% porosities shows a dynamical phase transition at around 600 mK due to the competition between thermal fluctuation and disorder: crystals grow via creep at high temperatures and via avalanche at low temperatures. In a very high porosity 99.5% aerogel, however, the transition had not been observed in our previous publication (Nomura et al. in Phys. Rev. Lett. 101:175703, 2008). We improved the spatial resolution of the video image and found that the 99.5% aerogel did have the transition at around 200 mK, which is much lower than those of the lower porosities. The avalanche size is significantly smaller in the 99.5% aerogel. The reduction in the transition temperature and avalanche size may be the consequence of weaker disorder for the crystallization in the very high porosity aerogel.     

Bradykinin stimulates type II alveolar cells to release neutrophil and monocyte chemotactic activity and inflammatory cytokines

In the present study, we evaluated the potential of bradykinin (BK) to induce the release of neutrophil and monocyte chemotactic activity (NCA and MCA) and cytokines from an alveolar type II epithelial cell line, A549 cells. BK stimulated A549 cells to release NCA and MCA in a dose- and time-dependent manner (P < 0.001). Checkerboard analysis revealed that both NCA and MCA involved chemotactic and chemokinetic activity. Molecular sieve column chromatography showed three molecular weight masses (near 19 kd, 8 kd, and 400 d) for NCA and several molecular weight peaks (near 66 kd, 25 kd, 19 kd, 16 kd, and 400 d) for MCA. The release of NCA and MCA was inhibited by cycloheximide and lipoxygenase inhibitors (P < 0.01). The NCA and MCA were inhibited by leukotriene B4 (LTB4) receptor antagonist (P < 0.01), and the concentration of LTB4 was high enough for NCA and MCA. Antibodies to interleukin (IL)-8 and granulocyte colony-stimulating factor (G-CSF) attenuated NCA (P < 0.01), and antibodies to monocyte chemotactic protein-1 (MCP-1), G-CSF, and transforming growth factor (TGF)-beta attenuated MCA (P < 0.01). The levels of IL-8, G-CSF, MCP-1, and TGF-beta increased time dependently (P < 0.01). BK also stimulated the release of ILeukin-6 from A549 cells (P < 0.001). The receptors responsible for the release of NCA, MCA, and individual chemokines involved both BKB1 and BKB2 receptors. These data suggest that BK may stimulate alveolar type II pneumocytes to release inflammatory cytokines, which then may modulate the lung inflammation.     

Impact of corticotropin-releasing hormone on gastrointestinal motility and adrenocorticotropic hormone in normal controls and patients with irritable bowel syndrome

The present study adopted a prospective design to explore relationships among various types of social support and depression. Four types of social support, namely network support, instrumental enacted support, socio-emotional enacted support, and perceived support, were assessed in a sample of Chinese adolescents. Results revealed that perceived support was related to a reduction of subsequent depression for both male and female adolescents. In addition, instrumental enacted support was a significant predictor of subsequent depression for male adolescents, whereas socioemotional enacted support was a significant predictor of subsequent depression for female adolescents. Functional differences in the types of social support for Chinese male and female adolescents, as well as implications for clinical intervention, are discussed.     

Influence of aging on rolipram-sensitive phosphodiesterase activity and [3H]rolipram binding in the rat brain

Cytolytic T cells were generated in vitro by culturing purified Balb/c CD4+ T cells with irradiated C57Bl/6 (B6) splenocytes plus anti-IL-4 mAb. Matched, noncytotoxic T cells were similarly generated by culturing purified Balb/c CD4+ T cells with irradiated B6 splenocytes plus recombinant murine IL-4. The latter T cells displayed to cytolytic activity, even in lectin-mediated lysis assays, but produced characteristic cytokines upon contact with specific alloantigens. Transfusion of cytolytic T cell populations into Balb/c SCID mice bearing B6 cardiac allografts resulted in acute allograft rejection within 5 to 10 days. Transfusion of noncytolytic T cell populations into Balb/c SCID mice bearing B6 cardiac allografts also resulted in acute allograft rejection within 7 to 10 days. Limiting dilution analysis (LDA) of infiltrating cells recovered from rejected allografts after collagenase digestion demonstrated that the CD4+ T cells retained their cytolytic or noncytolytic functional phenotypes in vivo throughout the rejection process. These data demonstrate that isolated CD4+ T cell populations can promote rapid acute cardiac allograft rejection, and that cytolytic activity is not necessary for this acute rejection response.     

Normally Off n-Channel GaN MOSFETs on Si Substrates Using an SAG Technique and Ion Implantation

We have demonstrated n-channel gallium nitride (GaN) MOSFETs using a selective area growth (SAG) technique and ion implantation on a silicon substrate. Both MOSFETs realized good normally off operations. The MOSFET using the SAG technique showed a large drain current of 112 mA/mm, a lower leakage current, and a high field mobility of 113 cm²/V . s, which is, to our knowledge, the best for a GaN MOSFET on a silicon substrate.