Superconducting zinc heat switch for continuous nuclear demagnetization refrigerator and sub-mK experiments

We have developed and tested a zinc superconducting heat switch suitable for magnetic refrigeration and calorimetric experiments at sub-millikevin (sub-mK) temperatures. The specific application here is an adiabatic demagnetization refrigerator with two PrNi$_{5}$ nuclear stages, which can keep a temperature of 0.8 mK continuously, (CNDR) proposed by Toda et al. (J. Phys.: Conf. Ser. 969, 012093 (2018). The switch consists of six high-purity zinc foils of 0.25 mm thick which contact seven silver foils by diffusive bonding. The silver foils are electron beam welded to silver rods that are thermal links to other components. The choice of the thin zinc foils is due to reduce the magnetic latent heat on switching and the contact thermal resistance under a constraint on the aspect ratio of the switch element. The measured thermal conductance of the whole switch assembly in the normal (closed) state, $K_\mathrm{closed}$, agrees very well down to 70 mK with the value estimated from the residual electrical resistance 114 n$\mathrm{\Omega}$ at 4.2 K, indicating the validity of the Wiedemann-Franz law for zinc. The measured thermal conductance in the superconducting (open) state, $K_\mathrm{open}$, follows nicely the prediction from the BCS theory and approaches the value expected from the Debye model for thermal phonons near 70 mK. The heat leak through the HSW from the higher temperature side of 30 mK at most is estimated to be less than 0.5 nW, which is much lower than the expected cooling power ($= 10$ nW) of the CNDR at 0.8 mK . The switching ratio $K_\mathrm{closed}/K_\mathrm{open}$ extrapolated to 30 mK, is as high as 5$\times10^4$. All the test results meet the requirements for the CNDR and, for example, heat capacity measurements at sub-mK.Comment: 15 pages, 5 figure

Dewatering of slurry with poor filterability in basket centrifuge: discharge of supernatant using bypass filter medium

When centrifugal dewatering in basket centrifuge involves the sedimentation of particles in feed slurry, the slurry separates into two phases: supernatant and cake. The dewatering proceeds as the supernatant permeates through the cake. However, if the cake formed has poor permeability, it takes longer time to reach the desired moisture content. In this study , a new method is proposed to dewater slurry which forms cake with poor permeability and a comparison was made with the conventional design. In the proposed design, the filter media is placed not only on the circuit, but also at the bottom of the filter chamber. Thus, even though the cake formed has a high hydrodynamic resistance, the supernatant could be discharged because the filter medium at the bottom has less hydrodynamic resistance than the cake and therefore works as a bypass. It is known from the previous study that when the supernatant is totally discharged, the cake will undergo a consolidation process, which will make the cake more compact. Therefore, it is postulated that the bypass filter medium would improve the dewatering efficiency drastically. The results obtained is that the supernatant still remained in the filter chamber even after 300 s of dewatering when the conventional design was used, while the supernatant was completely discharged within 150 s when the new design was used. Thus, it can be concluded that the filter medium at the bottom of the filter chamber worked as a bypass and improved the dewatering performance

Analysis of stepwise expression of sake fermentation broth

In the sake brewing, expression is used for the separation of liquid from the fermentation broth. Although the period of expression has to be as short as possible in order to prevent the sake from losing flavour, practically it takes much time to complete expression because of the highly compressible materials (e.g. proteins and starch) in the broth. For the expression of highly compressible materials, it is known empirically that the applied pressure should be low at the beginning of the expression and increased stepwise as the expression proceeds. In this study, we propose a method for the analysis of stepwise expression of highly compressible materials. The fermentation broth of sake was used as the experimental material. The experimental apparatus of constant pressure expression utilised in this study essentially consists of a vertical cylinder with a movable piston. The change in thickness of the material in the cylinder with the time was measured by a dial gauge. The mechanism of liquid removal is filtration at the beginning of expression, followed by consolidation. The filtration rate can be obtained by applying Ruth’s constant pressure filtration theory. In the consolidation period (i.e. after the end of the filtration), the deliquoring rate is calculated by the numerical analysis of the basic consolidation equation. However, because the formula expressing the distribution of solid compressive pressure pS of a filter cake with highly compressible materials has not been established well, the consolidation equation cannot be solved analytically. We therefore propose a new empirical equation representing the pS-distribution of a filter cake with highly compressible materials. The equation proposed in this study makes it possible to analyse the stepwise expression of highly compressible materials

Osteocyte Network; a Negative Regulatory System for Bone Mass Augmented by the Induction of Rankl in Osteoblasts and Sost in Osteocytes at Unloading

Reduced mechanical stress is a major cause of osteoporosis in the elderly, and the osteocyte network, which comprises a communication system through processes and canaliculi throughout bone, is thought to be a mechanosensor and mechanotransduction system; however, the functions of osteocytes are still controversial and remain to be clarified. Unexpectedly, we found that overexpression of BCL2 in osteoblasts eventually caused osteocyte apoptosis. Osteoblast and osteoclast differentiation were unaffected by BCL2 transgene in vitro. However, the cortical bone mass increased due to enhanced osteoblast function and suppressed osteoclastogenesis at 4 months of age, when the frequency of TUNEL-positive lacunae reached 75%. In the unloaded condition, the trabecular bone mass decreased in both wild-type and BCL2 transgenic mice at 6 weeks of age, while it decreased due to impaired osteoblast function and enhanced osteoclastogenesis in wild-type mice but not in BCL2 transgenic mice at 4 months of age. Rankl and Opg were highly expressed in osteocytes, but Rankl expression in osteoblasts but not in osteocytes was increased at unloading in wild-type mice but not in BCL2 transgenic mice at 4 months of age. Sost was locally induced at unloading in wild-type mice but not in BCL2 transgenic mice, and the dissemination of Sost was severely interrupted in BCL2 transgenic mice, showing the severely impaired osteocyte network. These findings indicate that the osteocyte network is required for the upregulation of Rankl in osteoblasts and Sost in osteocytes in the unloaded condition. These findings suggest that the osteocyte network negatively regulate bone mass by inhibiting osteoblast function and activating osteoclastogenesis, and these functions are augmented in the unloaded condition at least partly through the upregulation of Rankl expression in osteoblasts and that of Sost in osteocytes, although it cannot be excluded that low BCL2 transgene expression in osteoblasts contributed to the enhanced osteoblast function

Osteocalcin is necessary for the alignment of apatite crystallites, but not glucose metabolism, testosterone synthesis, or muscle mass

The strength of bone depends on bone quantity and quality. Osteocalcin (Ocn) is the most abundant noncollagenous protein in bone and is produced by osteoblasts. It has been previously claimed that Ocn inhibits bone formation and also functions as a hormone to regulate insulin secretion in the pancreas, testosterone synthesis in the testes, and muscle mass. We generated Ocn-deficient (Ocn–/–) mice by deleting Bglap and Bglap2. Analysis of Ocn–/ –mice revealed that Ocn is not involved in the regulation of bone quantity, glucose metabolism, testosterone synthesis, or muscle mass. The orientation degree of collagen fibrils and size of biological apatite (BAp) crystallites in the c-axis were normal in the Ocn–/–bone. However, the crystallographic orientation of the BAp c-axis, which is normally parallel to collagen fibrils, was severely disrupted, resulting in reduced bone strength. These results demonstrate that Ocn is required for bone quality and strength by adjusting the alignment of BAp crystallites parallel to collagen fibrils; but it does not function as a hormone.Osteocalcin is necessary for the alignment of apatite crystallites, but not glucose metabolism, testosterone synthesis, or muscle mass. Takeshi Moriishi et al. PLOS Genetics. 2020. 5(28)doi.org/10.1371/journal.pgen.100858

Overexpression of Bcl2 in Osteoblasts Inhibits Osteoblast Differentiation and Induces Osteocyte Apoptosis

Bcl2 subfamily proteins, including Bcl2 and Bcl-XL, inhibit apoptosis. As osteoblast apoptosis is in part responsible for osteoporosis in sex steroid deficiency, glucocorticoid excess, and aging, bone loss might be inhibited by the upregulation of Bcl2; however, the effects of Bcl2 overexpression on osteoblast differentiation and bone development and maintenance have not been fully investigated. To investigate these issues, we established two lines of osteoblast-specific BCL2 transgenic mice. In BCL2 transgenic mice, bone volume was increased at 6 weeks of age but not at 10 weeks of age compared with wild-type mice. The numbers of osteoblasts and osteocytes increased, but osteoid thickness and the bone formation rate were reduced in BCL2 transgenic mice with high expression at 10 weeks of age. The number of BrdU-positive cells was increased but that of TUNEL-positive cells was unaltered at 2 and 6 weeks of age. Osteoblast differentiation was inhibited, as shown by reduced Col1a1 and osteocalcin expression. Osteoblast differentiation of calvarial cells from BCL2 transgenic mice also fell in vitro. Overexpression of BCL2 in primary osteoblasts had no effect on osteoclastogenesis in co-culture with bone marrow cells. Unexpectedly, overexpression of BCL2 in osteoblasts eventually caused osteocyte apoptosis. Osteocytes, which had a reduced number of processes, gradually died with apoptotic structural alterations and the expression of apoptosis-related molecules, and dead osteocytes accumulated in cortical bone. These findings indicate that overexpression of BCL2 in osteoblasts inhibits osteoblast differentiation, reduces osteocyte processes, and causes osteocyte apoptosis

Study to transit of achievement motivations in psychiatric social worker\u27s training

本研究の目的は,精神保健福祉援助実習前後での実習生の達成動機の変化を明らかにするとともに,達成動機に影響を与える要因について検討することであった.調査の結果,(1)自己充実的達成動機の平均値は実習前で51.72点,実習後で53.33点であり,実習後に上昇することが示された.また,非参加群との比較においても両群の間に有意な差が認められ,参加群で自己充実的達成動機が高いことが明らかとなった.(2)競争的達成動機の平均値は実習前で33.13点,実習後で33.62点であり,実習前後では有意な変化は認められなかった.しかし,非参加群との比較においては両群の間に有意な差が認められ,参加群で競争的達成動機が高いことが明らかとなった.(3)実習生の達成動機に影響を与える要因として,「実習に対する不安」と「精神保健福祉ボランティア等の事前体験学習の有無」の2つの項目で関連性が認められ,実習不安が高いほど「自己充実的達成動機」は低下し,また,精神保健福祉ボランティア等の事前体験学習を経験した学生で「自己充実的達成動機」が上昇することが明らかとなった.以上の結果を踏まえて,実習において達成動機(特に自己充実的達成動機)を高める可能性のある目標設定モデルを用いた現場実習指導のあり方,さらには学生への教育的支援の方法について論じた