Development of Polyol Ester Refrigeration Oils for HFO Refrigerants

Recently, R32 refrigerant, which has low global warming potential (GWP), attracts much attention as an alternative one instead of R410A and has started to be used in practical system of room air conditioner (RAC), but compared with natural refrigerants, its GWP of 675 is still high and it is required to use refrigerants with much lower GWP. In addition, although R134a (GWP=1300) is widely used for mobile air conditioner systems (MAC), it has been decided by MAC directive in Europe that refrigerants whose GWP is over 150 can no longer be available in future. In such a situation, HFO refrigerants like R1234yf, R1234ze and AMOLEA [1] are considered as candidates for next-generation refrigerants because of their much lower GWP. Therefore, at the same time, it is required to develop refrigeration oils which have good compatibility with HFO refrigerants for RAC. One of the characteristics of HFO refrigerants is that their miscibility with refrigeration oils is equal to or greater than that of HFCs. However, the problem is that HFOs have a double bond in their molecular structure, resulting in their lower chemical stability than that of HFCs. We developed polyol ester (POE) refrigeration oil with high chemical stability under HFO atmospheres by improving formulation of additives. In this study, we will report the method and the characteristics of lubricity under HFOs. [1] M. Fukushima, M. Hashimoto, Development of Low-GWP Alternative Refrigerants , JRAIA the International Symposium on New Refrigerants and Environmental Technology 2014, (2014), 292-299

Prediction of the Fracture Location by Tensile Tests of Gray Cast Iron Based on the Dimensional Changes of Graphite Flakes

Gray cast iron has been used as a component in various mechanical parts, such as the blocks and heads of automobile and marine engines, cylinder liners for internal combustion engines, and machine tool bases. It is desirable because of its good castability and machinability, damping characteristics, and high performance-to-cost ratio. On the other hand, weak graphite flakes present in gray cast iron serve as stress concentrators and adversely affect the material strength. Therefore, it is crucial to examine the relationship between the distribution of graphite flakes and the strength or fracture of gray cast iron. In this study, tensile tests on gray cast iron were carried out using a plate specimen and observed by scanning electron microscopy, and the microscopic deformation was observed on the specimen surface. Particularly, the change in the size of graphite flakes during the tensile tests was examined, and the observed trend was discussed. The experimental results reveal that the dimensional changes in the graphite flakes vary in the observed area and that the final fracture occurs in an area where a large dimensional change is observed, suggesting that the fracture location or critical parts of gray cast iron can be predicted from the dimensional changes of the graphite flakes at an early stage of deformation

Finite Element Study of the Effect of Internal Cracks on Surface Profile Change due to Low Loading of Turbine Blade

Turbine blades for thermal power plants are exposed to severe environments, making it necessary to ensure safety against damage, such as crack formation. A previous method detected internal cracks by applying a small load to a target member. Changes in the surface properties of the material were detected before and after the load using a digital holographic microscope and a digital height correlation method. In this study, this technique was applied in combination with finite element analysis using a 2D and 3D model simulating the turbine blades. Analysis clarified that the change in the surface properties under a small load varied according to the presence or absence of a crack, and elucidated the strain distribution that caused the difference in the change. In addition, analyses of the 2D model considering the material anisotropy and thermal barrier coating were conducted. The difference in the change in the surface properties and strain distribution according to the presence or absence of cracks was elucidated. The difference in the change in the top surface height distribution of the materials with and without a crack was directly proportional to the crack length. As the value was large with respect to the vertical resolution of 0.2 nm of the digital holographic microscope, the change could be detected by the microscope

Bazedoxifene, a selective estrogen receptor modulator, reduces cerebral aneurysm rupture in Ovariectomized rats.

BackgroundEstrogen deficiency is thought to be responsible for the higher frequency of aneurysmal subarachnoid hemorrhage in post- than premenopausal women. Estrogen replacement therapy appears to reduce this risk but is associated with significant side effects. We tested our hypothesis that bazedoxifene, a clinically used selective estrogen receptor (ER) modulator with fewer estrogenic side effects, reduces cerebral aneurysm rupture in a new model of ovariectomized rats.MethodsTen-week-old female Sprague-Dawley rats were subjected to ovariectomy, hemodynamic changes, and hypertension to induce aneurysms (ovariectomized aneurysm rats) and treated with vehicle or with 0.3 or 1.0 mg/kg/day bazedoxifene. They were compared with sham-ovariectomized rats subjected to hypertension and hemodynamic changes (HT rats). The vasoprotective effects of bazedoxifene and the mechanisms underlying its efficacy were analyzed.ResultsDuring 12 weeks of observation, the incidence of aneurysm rupture was 52% in ovariectomized rats. With no effect on the blood pressure, treatment with 0.3 or 1.0 mg/kg/day bazedoxifene lowered this rate to 11 and 17%, almost the same as in HT rats (17%). In ovariectomized rats, the mRNA level of ERα, ERβ, and the tissue inhibitor of metalloproteinase-2 was downregulated in the cerebral artery prone to rupture at 5 weeks after aneurysm induction; the mRNA level of interleukin-1β and the matrix metalloproteinase-9 was upregulated. In HT rats, bazedoxifene restored the mRNA level of ERα and ERβ and decreased the level of interleukin-1β and matrix metalloproteinase-9. These findings suggest that bazedoxifene was protective against aneurysmal rupture by alleviating the vascular inflammation and degradation exacerbated by the decrease in ERα and ERβ.ConclusionsOur observation that bazedoxifene decreased the incidence of aneurysmal rupture in ovariectomized rats warrants further studies to validate this response in humans

Hyperhomocysteinemia induced by excessive methionine intake promotes rupture of cerebral aneurysms in ovariectomized rats.

BackgroundHyperhomocysteinemia (HHcy) is associated with inflammation and a rise in the expression of matrix metalloproteinase-9 (MMP-9) in the vascular wall. However, the role of HHcy in the growth and rupture of cerebral aneurysms remains unclear.MethodsThirteen-week-old female Sprague-Dawley rats were subject to bilateral ovariectomy and ligation of the right common carotid artery and fed an 8 % high-salt diet to induce cerebral aneurysms. Two weeks later, they underwent ligation of the bilateral posterior renal arteries. They were divided into two groups and methionine (MET) was or was not added to their drinking water. In another set of experiments, the role of folic acid (FA) against cerebral aneurysms was assessed.ResultsDuring a 12-week observation period, subarachnoid hemorrhage due to aneurysm rupture was observed at the anterior communicating artery (AcomA) or the posterior half of the circle of Willis. HHcy induced by excessive MET intake significantly increased the incidence of ruptured aneurysms at 6-8 weeks. At the AcomA of rats treated with MET, we observed the promotion of aneurysmal growth and infiltration by M1 macrophages. Furthermore, the mRNA level of MMP-9, the ratio of MMP-9 to the tissue inhibitor of metalloproteinase-2, and the level of interleukin-6 were higher in these rats. Treatment with FA abolished the effect of MET, suggesting that the inflammatory response and vascular degradation at the AcomA is attributable to HHcy due to excessive MET intake.ConclusionsWe first demonstrate that in hypertensive ovariectomized rats, HHcy induced by excessive MET intake may be associated with the propensity of the aneurysm wall to rupture

Influence of Cigarette Smoking on Estimated Glomerular Filtration Rate (eGFR) in Japanese Male Workers

The link between changes in estimated glomerular filtration rate (eGFR) and cigarette smoking was evaluated in Japanese male workers with a 5-year follow-up. We examined the data of 456 Japanese male workers, aged 22-70 years, who were taking no medications, and from this group, 286 men (43.5±8.2 years) were followed for 5-years. Habits of cigarette smoking were obtained during interviews by well-trained staff. The influence of cigarette smoking on eGFR was evaluated. In the first analysis, there was no significant difference in eGFR between subjects with and without cigarette smoking. In the second analysis, eGFR was significantly reduced after 5 years in all subjects. Changes in eGFR in subjects with cigarette smoking (－1.90±12.31ml/min/1.73m2) were significantly smaller than those in subjects without cigarette smoking (－4.97±12.05ml/min/1.73m2). At follow-up, we found that eGFR was weakly and negatively correlated with the number of cigarettes smoked (/day). The present study indicated that cigarette smoking may be an important modifiable factor for eGFR in Japanese male workers who are not taking any medications

遺伝子発現スコアリングシステムを用いた食道類基底細胞癌の鑑別診断法の構築

博士（医学）福島県立医科大

Effect of Lubrication and Forging Load on Surface Roughness, Residual Stress, and Deformation of Cold Forging Tools

Cold forging is a metal forming that which uses localized compressive force at room temperature. During the cold forging process, the tool is subjected to extremely high loads and abrasive wear. Lubrication plays an important role in cold forging to improve product quality and tool life by preventing direct metallic contact. Surface roughness and residual stress also greatly affects the service life of a tool. In this study, variations in surface roughness, residual stress, and specimen deformation with the number of cold forging cycles were investigated under different forging conditions. Specimens that were made of heat-treated SKH51 (59-61 HRC), a high-speed tool steel with a polished working surface, were used. The specimens were subjected to an upsetting process. Compressive residual stress, surface roughness, and specimen deformation showed a positive relationship with the number of forging cycles up to a certain limit and became almost constant in most of the forging conditions. A larger change in residual stress and surface roughness was observed at the center of the specimens in all the forging conditions. The effect of the magnitude of the forging load on the above discussed parameters is large when compared to the effect of the lubrication conditions