A Study on PWM Bypass Capacity Control of Scroll Compressors

A pulse width modulation (PWM) bypass capacity control technique for air conditioners has been developed to achieve high scroll compressor efficiency over a wide capacity range, and we investigated the technique’s fundamental characteristics in this study. With this capacity control technique, the refrigerant flow rate is controlled by periodically switching a full load mode, in which the refrigerant is compressed and discharged out of the compressor, and an unload mode, in which the refrigerant is not compressed so that the power needed to compress is unnecessary. In this study, we measured the pressure and input power of a compressor using the control technique to clarify the technique’s dynamic characteristics. We also developed a numerical simulation model to predict the dynamic behavior of the refrigerant. The calculated pressures were found to be in good agreement with the measured pressures and were used to estimate the relation between the PWM period and the efficiency or the discharge flow rate. Since the PWM period could not be determined by the demanded load capacity, the estimations were used to determine it. Using this period, we carried out performance tests of a compressor with PWM bypass capacity control. The results showed the capacity reached 30% of the lower limit of rotational speed and that the calculated efficiencies agreed well with the experimental findings

Current status of MHI’s CO2 recovery technology and optimization of CO2 recovery plant with a PC fired power plant

AbstractIt is the opinion of the authors that CO2 Capture and Storage (CCS) technology can significantly contribute as an effective countermeasure against climate change, allowing us to continue the utilization of fossil fuels for primary energy production. However for this technology to be widely deployed on a commercial basis there are three key issues that need to be addressed; (1) Reduction in energy consumption, (2) Efficient integration with other environmental control equipment of a PC power plant and (3) Reduction in the decrease of net electrical output.MHI has delivered multiple commercial CO2 recovery plants in the chemical and fertilizer industries, which recover CO2 from natural gas fired flue gas, with four commercial plants in operation and another four under construction, all utilizing the proprietary KM-CDR process.In order to gain experience with CO2 recovery from a coal fired flue gas stream, Mitsubishi Heavy Industries (MHI), together with a subsidy from RITE and cooperation from J-POWER, constructed a 10 metric ton per day (T/D) CO2 recovery demonstration plant at the 2×500 MW Matsushima power station in southern Japan. This demonstration plant has subsequently achieved more than 4,000 hours of successful test operation during 2006–2007 with a further 1,000 hours during 2008, and testing continues today. The demonstration testing confirmed that the KM-CDR process is applicable to coal fired flue gas streams. Future research priorities include the improved integration of the CO2 recovery process with the flue gas pre-treatment components and the additional optimization of removal and separation methods for coal based impurities accumulating in the absorbent.An issue of concern for power plant operators is the reduction of the net electrical output due to the demands of CO2 recovery process. MHI has made significant improvements in this area and in the efficiency of absorbents. However, it is necessary to further reduce the adverse impact on the net electrical output of the power plant via astute integration of the energy transferred between the power plant and the Post Combustion CO2 Capture (PCC) plant. MHI is investigating the following concepts; (1) Utilizing the waste heat of the PCC plant for the power plant, (2) Utilizing heat recovery from the flue gas for the CO2 recovery process and (3) Utilizing the compression heat of the CO2 compressor for the CO2 recovery process

Aquaporin 4 Expression in the mdx Mouse Diaphragm

Expression of aquaporin (AQP) 4 in the surface membranes of skeletal myofibers is well established; however, its functional significance is still unknown. The alterations of AQP4 expressions in dystrophic muscles at RNA and protein levels have been reported in various dystrophic muscles such as dystrophinopathy, dysferlinopathy, and sarcoglycanopathy. We are interested in the relationship between the severity of dystrophic muscle degeneration and the expression of AQP4. Here we compared the AQP4 expression of the limb muscles with that of diaphragms in both mdx and control mice. The dystrophic muscle degeneration, such as rounding profile of cross sectional myofiber shape, dense eosin staining, central nuclei, and endomysial fibrosis in mdx mice, were more marked in diaphragms than in limb muscles. The decrease of AQP4 expression at protein level was more marked in diaphragms than in the limb muscles of mdx mice. However, the expression of AQP4 mRNA in the diaphragms of mdx mice was not reduced in comparison with limb muscles of mdx mice. The present study revealed that AQP4 expression at protein level was correlated with the severity of dystrophic changes in muscle tissues of mdx mice

Low back pain and causative movements in pregnancy: a prospective cohort study

Background: Low back pain (LBP) during pregnancy might be strongly related to posture and movements of the body, and its management is a clinically important issue. The purpose of this study was to investigate the activities related to LBP during pregnancy. Methods: Participants included 275 women before 12 weeks of pregnancy. The women were evaluated at 12, 24, 30, and 36 weeks of pregnancy. The intensity of LBP was assessed using the Numerical Rating Scale (NRS). Movements related to LBP were investigated by free descriptive answers. Descriptive statistics were used to compile the movements that pregnant women thought induced LBP at each evaluation. Subsequently, a linear regression analysis was performed to evaluate the degree of association of certain movements with LBP using the data of participants who had LBP. The intensity of LBP (NRS score) was specified as the dependent variable, the movements that were related to pain were specified as the independent variables at the analysis. A significance threshold was set at 0.05. Results: The final sample used in the analyses was 254, 249, 258, and 245 women at 12, 24, 30, and 36 weeks of pregnancy, respectively. There were 16 kinds of movements that induced LBP and all of them were daily activities rather than special movements that require extra task or effort. As pregnancy progressed, less number of participants attributed pain to a specific movement. At all evaluations, movements, especially sitting up, standing up from a chair, and tossing and turning were thought to be related to LBP. Furthermore, standing up from a chair and tossing and turning were significantly related to LBP throughout the pregnancy. In contrast, lying down and sitting up were significantly related to LBP but the relationship did not continue till late pregnancy. Conclusions: Daily routine activity is related to LBP during pregnancy. These results suggest that recommendations for pregnant women about basic physical movements, such as ways of standing up that reduce the load on the body might be useful in the management of LBP

Characteristics of systolic and diastolic potentials recorded in the left interventricular septum in verapamil-sensitive left ventricular tachycardia

We studied the electrophysiological characteristics of systolic (SP) and diastolic (DP) potentials recorded during sinus rhythm (SR) in the left interventricular septum of a 27 year-old woman presenting with verapamil-sensitive idiopathic left ventricular tachycardia (VT). During SR, and during VT, SP was activated from ventricular base-to-apex, and DP from apex-to-base. SP and DP were both detected at the site of successful ablation during SR, whereas during VT, DP was detected away from the earliest activation site. Thus, SP apparently reflected a critical component of the reentrant circuit, while DP reflected the activation of a bystander pathway

Induction of metallothionein synthesis in cultured cells by substances released from endotoxin-activated macrophages.

The involvement of macrophages in the induction of metallothionein (MT) synthesis by bacterial endotoxin was studied in vitro. Rat peritoneal macrophages were incubated with endotoxin. The incubation medium from endotoxin-activated macrophages accelerated MT synthesis by human hepatic Chang cells. However, the incubation medium from non-activated macrophages did not. Endotoxin added to the culture medium of Chang cells was ineffective in inducing MT synthesis. The contents of zinc, copper and cadmium, which are primary inducers of MT, in the incubation medium of macrophages in the presence of endotoxin were not different from those in the absence of endotoxin. These results suggest that MT synthesis is induced by endotoxin-treated macrophages.</p

Aberrant methylation of the TDMR of the GTF2A1L promoter does not affect fertilisation rates via TESE in patients with hypospermatogenesis

Increasing evidence shows a relationship between epigenetic regulation and male infertility. The GTF2A1L gene promoter contains the DNA methylation site of a tissue-specific differentially methylated region (TDMR). Eighty-six patients with non-obstructive azoospermia were assessed for the DNA methylation state of CpG islands in the GTF2A1L promoter using testicular genomic DNA. Based on histological criteria, 26 of the 86 patients had normal spermatogenesis (controls), 17 had hypospermatogenesis and 26 had a Sertoli cell-only phenotype or tubular sclerosis. GTF2A1L TDMR methylation was significantly lower in testes DNA from control samples than from hypospermatogenic samples (P=0.029). Patients with hypospermatogenesis were divided into two subgroups: high DNA methylation (HM, n=5) and low DNA methylation (LM, n=12). The GTF2A1L TDMR methylation rate differed significantly between the HM and LM groups (P=0.0019), and GTF2A1L expression was significantly higher among the LM than in the HM patients (P=0.023). High TDMR methylation was correlated with low GTF2A1L gene expression levels. Both groups demonstrated relatively good outcomes with respect to sperm retrieval, fertilisation, pregnancy and childbirth rates. We observed that aberrant GTF2A1L gene expression was not correlated with fertilisation rates. The testicular sperm extraction (TESE) technique may be used to overcome male infertility due to aberrant TDMR methylation. © 2013 AJA, SIMM & SJTU. All rights reserved

Irregular atrial flutter following pulmonary vein isolation for persistent atrial fibrillation

AbstractA 65-year-old man with a history of refractory paroxysmal atrial fibrillation (AF) underwent catheter ablation for persistent AF lasting 2 months. AF was not terminated after complete isolation of the 4 pulmonary veins (PV). Instead, it was transformed to a sustained atrial tachyarrhythmia with beat-to-beat variability in the atrial cycle length. A 12-lead electrocardiogram during tachycardia showed negative flutter-like waves in the inferior leads. Entrainment pacing along the tricuspid annulus confirmed the diagnosis of irregular cavotricuspid isthmus (CTI)-dependent typical atrial flutter (AFL). Linear ablation of the CTI terminated AFL and restored sinus rhythm

Thrombocytopenia in pegylated interferon and ribavirin combination therapy for chronic hepatitis C

BACKGROUND: This study aimed to examine the therapeutic effect and prognostic indicators of pegylated interferon (PEG-IFN) and ribavirin (RBV) combination therapy in thrombocytopenic patients with chronic hepatitis C, hepatitis C virus (HCV)-related cirrhosis, and those who underwent splenectomy or partial splenic embolization (PSE). METHODS: Of 326 patients with HCV-related chronic liver disease (252 with genotype 1b and 74 with genotype 2a/2b) treated with PEG-IFN/RBV, 90 were diagnosed with cirrhosis. RESULTS: Regardless of the degree of thrombocytopenia, the administration rate was significantly higher in the splenectomy/PSE group compared to the cirrhosis group. However, in patients with genotype 1b, the sustained virological response (SVR) rate was significantly lower in the cirrhosis and the splenectomy/PSE groups compared to the chronic hepatitis group. No cirrhotic patients with platelets less than 80,000 achieved an SVR. Patients with genotype 2a/2b were more likely to achieve an SVR than genotype 1b. Prognostic factors for SVR in patients with genotype 1b included the absence of esophageal and gastric varices, high serum ALT, low AST/ALT ratio, and the major homo type of the IL28B gene. Splenectomy- or PSE-facilitated induction of IFN in patients with genotype 2a/2b was more likely to achieve an SVR by an IFN dose maintenance regimen. Patients with genotype 1b have a low SVR regardless of splenectomy/PSE. In particular, patients with a hetero/minor type of IL28B did not have an SVR. CONCLUSIONS: Splenectomy/PSE for IFN therapy should be performed in patients expected to achieve a treatment response, considering their genotype and IL28B