Mixed Lubrication Analysis of Vane Sliding Surface in Rotary Compressor Mechanisms

In the compression mechanisms of a rotary compressor for air conditioners, a vane and a rolling piston are provided to separate the suction chamber and the compression chamber. The rolling piston is driven by the crank, and revolves on the axis of the shaft eccentrically, and also rotates on its own axis. The vane undergoes reciprocating motion, and its top usually comes into contact with the rolling piston by the spring force and the discharge pressure. The lubricating condition between the vane top and the rolling piston is severe because the contact pressure is high owing to the line contact of the vane top. For the prevention of scuffing, abnormal wear and so on, it is important to clarify the lubricating characteristics between the vane top and the rolling piston. Because the normal force acting on piston at vane contact is greatly influenced by the friction of vane sliding surface between the vane and the vane-slot, a mixed lubrication analysis of the vane sliding surface between the vane and the vane-slot is required to obtain the normal force acting on piston at vane contact accurately. In order to investigate the lubricating characteristics between the vane top and the rolling piston, a numerical analysis of the motion of the rolling piston and the motion of the vane considering the mixed lubrication of the vane sliding surface has been performed. The cases of different friction coefficient of the vane sliding surface at solid contact were calculated, and the results were compared. As a result, the effects of the friction of the vane sliding surface on the lubricating characteristics between the vane top and the rolling piston have been made clear

The role of maternal-specific H3K9me3 modification in establishing imprinted X-chromosome inactivation and embryogenesis in mice

Maintaining a single active X-chromosome by repressing Xist is crucial for embryonic development in mice. Although the Xist activator RNF12/RLIM is present as a maternal factor, maternal Xist (Xm-Xist) is repressed during preimplantation phases to establish imprinted X-chromosome inactivation (XCI). Here we show, using a highly reproducible chromatin immunoprecipitation method that facilitates chromatin analysis of preimplantation embryos, that H3K9me3 is enriched at the Xist promoter region, preventing Xm-Xist activation by RNF12. The high levels of H3K9me3 at the Xist promoter region are lost in embryonic stem (ES) cells, and ES-cloned embryos show RNF12-dependent Xist expression. Moreover, lack of Xm-XCI in the trophectoderm, rather than loss of paternally expressed imprinted genes, is the primary cause of embryonic lethality in 70–80% of parthenogenotes immediately after implantation. This study reveals that H3K9me3 is involved in the imprinting that silences Xm-Xist. Our findings highlight the role of maternal-specific H3K9me3 modification in embryo development

Role of histamine H3 receptor in glucagon-secreting αTC1.6 cells

AbstractPancreatic α-cells secrete glucagon to maintain energy homeostasis. Although histamine has an important role in energy homeostasis, the expression and function of histamine receptors in pancreatic α-cells remains unknown. We found that the histamine H3 receptor (H3R) was expressed in mouse pancreatic α-cells and αTC1.6 cells, a mouse pancreatic α-cell line. H3R inhibited glucagon secretion from αTC1.6 cells by inhibiting an increase in intracellular Ca2+ concentration. We also found that immepip, a selective H3R agonist, decreased serum glucagon concentration in rats. These results suggest that H3R modulates glucagon secretion from pancreatic α-cells

Methionine Metabolism Regulates Maintenance and Differentiation of Human Pluripotent Stem Cells

SummaryMouse embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are in a high-flux metabolic state, with a high dependence on threonine catabolism. However, little is known regarding amino acid metabolism in human ESCs/iPSCs. We show that human ESCs/iPSCs require high amounts of methionine (Met) and express high levels of enzymes involved in Met metabolism. Met deprivation results in a rapid decrease in intracellular S-adenosylmethionine (SAM), triggering the activation of p53-p38 signaling, reducing NANOG expression, and poising human iPSC/ESCs for differentiation, follow by potentiated differentiation into all three germ layers. However, when exposed to prolonged Met deprivation, the cells undergo apoptosis. We also show that human ESCs/iPSCs have regulatory systems to maintain constant intracellular Met and SAM levels. Our findings show that SAM is a key regulator for maintaining undifferentiated pluripotent stem cells and regulating their differentiation

対流圏エアロゾルのキャラクタリゼーション

<p>MMS sensitivity of <i>dnaN</i> strains bearing mutations in <b>(A)</b> loop I (red), <b>(B)</b> loop II (blue) or <b>(C)</b> the central pore of the β clamp (green) was measured as described in <i>Materials and Methods</i>. This experiment was performed 4 times with 2 separate clones. Representative results shown.</p

A Giant Thymic Cyst Accompanied by Acute Mediastinitis

We encountered a rare case of thymic cyst accompanied by mediastinitis. A 39-year-old Japanese male presented with fever and chest pain. The chest CT revealed a mass composed of a lobular cystic lesion with inflammation, suggesting the onset of mediastinitis. A definitive histological diagnosis was not obtained, and we performed a thymectomy. Pathologically, the thymic cyst was accompanied by multiple cavities, mimicking thymic cysts, caused by the inflammatory abscess. The surrounding adipose tissue showed inflammatory cell infiltrations with chronic fibrosis. These findings indicate that clinicians should be aware that thymic cysts may cause severe mediastinitis