Study on Bearing Characteristics of Reciprocating Compressor for Refrigerator

In recent years, in order to reduce the energy consumption of refrigerators through reduction of input power and improved refrigeration capacity, reciprocating compressors are gradually converted to inverter type. Correspondingly, we have studied the sliding bearing characteristics of the crankshaft journal at variable speed which is the key to improving the efficiency of reciprocating compressor. Generally, the characteristics of a sliding bearing are explained with a Stribeck curve. In the fluid lubrication regime, there is sufficient lubricant between metal surfaces. As the rotational speed decreases, the viscous resistance is reduced and it will result in the reduction of friction coefficient. Conversely, it is widely known that further reduction of rotational speed will shift to boundary lubrication regime where the friction coefficient increases due to metal to metal contact. In the inverter reciprocating compressor, it is presumed that the sliding of crankshaft on bearing at high rotational speed is in fluid lubrication regime. The input power can be reduced with gradual decrease of friction coefficient by lowering rotational speed, but then the sliding characteristic of the crankshaft at each rotational speed was unclear such that when the speed is too low it will progress into the boundary lubrication regime. This paper explains our experimental study to obtain a Stribeck curve at low load, low speed, and low viscosity oil in inverter operation using a bearing tester that estimate sliding crankshaft on bearing. The results obtained enable the prediction of sliding characteristic of crankshaft and optimization of the bearing property in reciprocating compressor

Studies on Bamboo Pulp : Multistage Bleaching Process of Bamboo Kraft Pulp (Part 1)

In this experiment, several bleaching methods of bamboo kraft pulp used chlorine, alkali and Ca-hypochlorite on 4- to 7-stage bleaching process and were discussed from the stand point of brightness. 1) Amount of addition of total chlorine The chlorine required amount for unbleached bamboo kraft pulp is about 10% from the base of wood pulp by KMnO_4 value. It is possible to obtain bleached pulp which has brightness above 85 with less amount of chlorine by this multistage bleaching process. From this fact, it is hard to say that bamboo kraft pulp is more difficult to bleach than wood pulp. Namely on the 4-stage bleaching 9% of chlorine was required, but on the 6- and 7-stage bleaching process 6% of chlorine was satisfactory and brightness was 85～90. According to O.S. SPROUT, and W. TOOREY et al., the 5-stage bleaching process, Cl-Na-Cl-H-H, required 6.63% of total chlorine to obtained brightness of 86, and the 6-stage bleaching process also needed the same amount of chlorine. From the data of this experiment, bleachability of bamboo kraft pulp showed better results than wood kraft pulp. 2) Ratio of chlorine On the multistage bleaching process, the problems are how much chlorine and in what ratio should it be added on each stage for the most effective bleaching. Principally, it is considered that the best way is to add a large amount of chlorine on the first stage and decreased gradually. However, this report shown that the principal method is not always suitable from the relationship of chemical actions, and in the discussed chlorine ratio, it was decided that the ratio of Cl: Ca-hypochlorite was divided into definite ratios. Uusually the ratio of 7:3 or 8:2 was adapted to wood kraft pulp, but in actual industry it is not established and it is differed depending on the factory. [table] In the case of bamboo kraft pulp as shown in this experiment on the ratio of 4:6 or 6:4 was given good result. The effect of Cl: Ca-hypochlorite ratio was remarkable on the 4-stage bleaching process, but less with the increase of stages in process. It was impossible to neglect this effect and about equal ratio showed better results. 3) Bleaching method If brightness was required at about 80, the 4-stage bleaching process was enough for this purpose, and farther more if well controlled, brightness would be raised above 85. Higher value of brightness pulp was obtained constantly with 6-stage of bleaching process. It is assumed that the 7-stage bleaching process is not necessary because the results were same as the 6-stage bleaching process. The most adequate process in the 6-stage bleaching process was Cl-Na-H-Cl-Na-H or Cl-Na-Cl-Na-H-H

Exciton-relaxation dynamics in lead halides

We survey recent comprehensive studies of exciton relaxation in the crystals of lead halides. The luminescence and electron-spin-resonance studies have revealed that excitons in lead bromide spontaneously dissociate and both electrons and holes get self-trapped individually. Similar relaxation has been also clarified in lead chloride. The electron-hole separation is ascribed to repulsive correlation via acoustic phonons. Besides, on the basis of the temperature profiles of self-trapped states, we discuss the origin of luminescence components which are mainly induced under one-photon excitation into the exciton band in lead fluoride, lead chloride, and lead bromide.Comment: REVTeX, 5 pages, 5 figure

Energy metabolism during the maturation of reticulocyte in vitro

1. For the purpose to clarify the mechanism of the revolutional changes in energy metabolism during the reticulocyte maturation the metabolisms of glucose and of the pentose moieties of acid soluble nucleotides have been observed on rabbit reticulocytes incubated in vitro under various conditions. 2. The maturation of reticulocyte proceeds by using the energy produced by aerobic glycolysis and is arrested in the glucose deficient medium, but the pentose moieties of purine nucleotide and nucleoside added exogenously serve as the energy source for reticulocyte maturation even in the absence of glucose. 3. The test on the utility efficiency of glucose and inosine as the energy source for reticulocyte maturation revealed that glucose is used more effectively than the pentose moiety of inosine under aerobic condition, which is advantageous for reticulocyte maturation, and vice versa under anaerobic condition, which is comparable to the metabolism of mature red cell. 4. From these results it has been suggested that the maturation of reticulocyte is the process of degradation of RNA and acid soluble nucleotides supported by the aerobic glycolysis, where the degradation products of RNA and acid soluble purine nucleotides provide the purine derivatives as the material for ATP synthesis (36) and the pentose moieties as energy source. 5. A possible mechanism for the superior utility of glucose to nucleoside pentose during reticulocyte maturation and vice versa in mature red cell has been discussed.</p

Effects of Amelogenin on Proliferation, Differentiation, and Mineralization of Rat Bone Marrow Mesenchymal Stem Cells In Vitro

The aim of this study was to clarify the function of amelogenin, the major protein of enamel matrix derivative, on the proliferation, differentiation, and mineralization of cultured rat bone marrow stem cells (BMSCs), toward the establishment of future bone regenerative therapies. No differences in the morphology of BMSCs or in cell numbers were found between amelogenin addition and additive-free groups. The promotion of ALPase activity and the formation of mineralized nodules were detected at an early stage in amelogenin addition group. In quantitative real-time RT-PCR, mRNA expression of osteopontin, osteonectin, and type I collagen was promoted for 0.5 hours and 24 hours by addition of amelogenin. The mRNA expression of osteocalcin and DMP-1 was also stimulated for 24 hours and 0.5 hours, respectively, in amelogenin addition group. These findings clearly indicate that amelogenin promoted the differentiation and mineralization of rat BMSCs but did not affect cell proliferation or cell morphology

Super-chiral vibrational spectroscopy with metasurfaces for high-sensitive identification of alanine enantiomers

Chiral nature of an enantiomer can be characterized by circular dichroism (CD) spectroscopy, but such a technique usually suffers from weak signal even with a sophisticated optical instrument. Recent demonstrations of plasmonic metasurfaces showed that chiroptical interaction of molecules can be engineered, thereby greatly simplifying a measurement system with high sensing capability. Here, by exploiting super-chiral field in a metasurface, we experimentally demonstrate high-sensitive vibrational CD spectroscopy of alanine enantiomers, the smallest chiral amino acid. Under linearly polarized excitation, the metasurface consisting of an array of staggered Au nano-rods selectively produces the left- and right-handed super-chiral fields at 1600 cm−1, which spectrally overlaps with the functional group vibrations of alanine. In the Fourier-transform infrared spectrometer measurements, the mirror symmetric CD spectra of D- and L-alanine are clearly observed depending on the handedness of the metasurface, realizing the reliable identification of small chiral molecules. The corresponding numerical simulations reveal the underlying resonant chiroptical interaction of plasmonic modes of the metasurface and vibrational modes of alanine. Our approach demonstrates a high-sensitive vibrational CD spectroscopic technique, opening up a reliable chiral sensing platform for advanced infrared inspection technologies

Species-independent detection of RNA virus by representational difference analysis using non-ribosomal hexanucleotides for reverse transcription

A method for the isolation of genomic fragments of RNA virus based on cDNA representational difference analysis (cDNA RDA) was developed. cDNA RDA has been applied for the subtraction of poly(A)(+) RNAs but not for poly(A)(−) RNAs, such as RNA virus genomes, owing to the vast quantity of ribosomal RNAs. We constructed primers for inefficient reverse transcription of ribosomal sequences based on the distribution analysis of hexanucleotide patterns in ribosomal RNA. The analysis revealed that distributions of hexanucleotide patterns in ribosomal RNA and virus genome were different. We constructed 96 hexanucleotides (non-ribosomal hexanucleotides) and used them as mixed primers for reverse transcription of cDNA RDA. A synchronous analysis of hexanucleotide patterns in known viral sequences showed that all the known genomic-size viral sequences include non-ribosomal hexanucleotides. In a model experiment, when non-ribosomal hexanucleotides were used as primers, in vitro transcribed plasmid RNA was efficiently reverse transcribed when compared with ribosomal RNA of rat cells. Using non-ribosomal primers, the cDNA fragments of severe acute respiratory syndrome coronavirus and bovine parainfluenza virus 3 were efficiently amplified by subtracting the cDNA amplicons derived from uninfected cells from those that were derived from virus-infected cells. The results suggest that cDNA RDA with non-ribosomal primers can be used for species-independent detection of viruses, including new viruses

Higher Sensitivity in Induction of Apoptosis in Fibroblast Cell Lines Derived from LEC Strain Rat to Ultraviolet B Radiation

LECラット由来繊維芽細胞のUVBに対する感受性をコロニー形成法を用いて調べた結果、LECラット細胞はWKAHラット細胞に比べてUVBに対して高い感受性を示した。D37値からLECラット細胞ではWKAH細胞の1.5倍以上高い感受性が認められた。ラジカルスキャベンジャーとして働く0.5MDMSOの存在下で細胞にUVBを照射するとLEC、WKAH細胞ともにUVB照射のみと比べて生存率に大きな違いは認められなかった。この結果からUVB照射によって生じるフリーラジカルはUVB誘発細胞死にはあまり関与しないと考えられる。LECラット細胞においてUVB照射後のアポトーシスをフローサイトメーターで検出したところ、照射線量に依存して増加した。一方、WKAHラット細胞ではUVB照射後アポトーシスの増加は認められなかった。これらの結果からLECラット細胞のUVBに対する高い感受性はUVB誘発アポトーシスに依拠していることが示唆された