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

Intrinsic Spin Decay Length in Antiferromagnetic Insulator

We report intrinsic spin decay length of an antiferromagnetic insulator. We found that at an antiferromagnetic/ferromagnetic interface, a spin current generated by spin pumping is strongly suppressed by two-magnon scattering. By eliminating the two-magnon contribution, we discovered that the characteristic length of spin decay in NiO changes by two-orders of magnitude through the paramagnetic to antiferromagnetic transition. The spin decay length in the antiferromagnetic state is longer than 100 nm, which is an order of magnitude longer than previously believed. These results provide a crucial piece of information for the fundamental understanding of the physics of spin transport

Spin-orbit torques originating from bulk and interface in Pt-based structures

We investigated spin-orbit torques in prototypical Pt-based spintronic devices. We found that, in Pt/Ni and Pt/Fe bilayers, the damping-like torque efficiency depends on the thickness of the Pt layer. We also found that the damping-like torque efficiency is almost identical in the Pt/Ni and Pt/Fe bilayers despite the stronger spin memory loss at the Pt/Fe interface. These results suggest that although the dominant source of the damping-like torque is the bulk spin Hall effect in the Pt layer, a sizable damping-like torque is generated by the interface in the Pt/Fe bilayer due to the stronger interfacial spin-orbit coupling. In contrast to the damping-like torque, whose magnitude and sign are almost identical in the Pt/Ni and Pt/Fe bilayers, the field-like torque strongly depends on the choice of the ferromagnetic layer. The sign of the field-like torque originating from the bulk spin Hall effect in the Pt layer is opposite between the Pt/Ni and Pt/Fe bilayers, which can be attributed to the opposite sign of the imaginary part of the spin-mixing conductance. These results demonstrate that the spin-orbit torques are quite sensitive to the electronic structure of the FM layer.Comment: The analysis has been revised based on the ST-FMR signals at higher frequencie

Synthesis and Metal-Complexation Ability of Cross-Linking Materials Containing Noria-Templated Cavities with Pendant Carboxylic Acid Groups

We synthesized noria-containing cross-linking materials, Cross(Noria-MA-co-DM[n]m), by radical polymerization of a noria derivative with pendant methacryloyl groups (noria-MA) and α, ω-alkanedimethacrylamides (DM[n], n = 3, 6, 12) at feed ratios of noria-MA/DM[n] = 1/2.4, 1/12, and 1/24 (m = 2.4, 12. and 24). Alkaline hydrolysis reaction of Cross(Noria-MA-co-DM[n]m) removed the noria moieties to give corresponding cross-linking materials, Cross-COOH-DM[n]m, containing noria-templated fixed cavities with pendant carboxylic acid groups. Among the noria-containing cross-linking materials, Cross(Noria-MA-co-DM[6]24) showed the greatest extent of removal of noria upon hydrolysis. Nitrogen and carbon dioxide absorption studies indicated that Cross(Noria-MA-co-DM[6]24) contains fixed cavities, whereas Cross-COOH-DM[6]24 does not in the solid (unswollen) state. Examination of the inclusion-complex-forming ability of the synthesized cross-linking materials using aqueous solutions of metal ions revealed that Cross-COOH-DM[6]24 has the greatest absorption capacity. These results indicate that Cross-COOH-DM[6]24 indeed contains noria-templated cavities that can accommodate metal ions in aqueous solution.exterior and a hydrophobic interior, and form complexes selectively with organic compounds in water[14]. Polyrotaxanes[15-17] and nanotubes[18] also have the ability to form complexes with organic compounds. On the other hand, we synthesized a ladder-type cyclic oligomer, which we called noria (water-wheel in Latin), by means of one-pot reaction using resorcinol and 1,5-pentanedial in high yield.[19] Single-crystal X-ray analysis confirmed that noria has 24 hydroxyl groups, 6 cavities in the side, and a large hydrophobic central hole, i.e., a water-wheel-like structure (Scheme 1). A noria derivative (noria-COOEt) containing carboxylic ester moieties could form a complex with Rb+ ion, which was apparently enclosed in the central hole in the molecule. Other noria derivatives[20 - 27] and noria-like macrocycle compounds [28 - 31] have since been synthesized and their applications have been investigated.This is a product of research which was financially supported (in part) by the Kansai University Fund for Supporting Outlay Research Centers, 2017. “Development of new materials and new processes for establishment of advanced separation system for various metals”

ASSOCIATIONS BETWEEN EXERCISE-INDUCED FLATTENING OF FOOT ARCH AND FATIGUE OF EXTRINSIC AND INTRINSIC FOOT MUSCLES

We aimed to examine the associations between exercise-induced flattening of the foot arch and fatigue of extrinsic and intrinsic foot muscles. Fifteen male participants repeated 100 hops/set until they could no longer maintain the hop frequency or had completed 30 sets. The sagittal plane range of motion (ROM) of the midfoot during stance phase significantly decreased at the final set compared to the initial set (-8.8°). After the fatigue task, MRI T2 relaxation time in all measured extrinsic and intrinsic foot muscles significantly increased (17.2‒37.4%); however, only its increase in the tibialis posterior (TP) correlated with the relative change in midfoot ROM (r = 0.684). These results suggest that fatigue of TP is associated with the occurrence of flattening of the foot arch. This study provides a clinical implication that monitoring midfoot kinematics can be used to assess the condition of TP

Role of adenosine in the renal responses to contrast medium

Role of adenosine in the renal responses to contrast medium. Despite the development of non-ionic radiographic contrast media (CM), CM-induced nephropathy is a clinically important problem in patients with pre-existing renal insufficiency. We examined the effects of non-ionic CM (iohexol) on renal function in conscious dogs with and without renal insufficiency, and evaluated the effects of a non-selective (theophylline), an A1 selective (KW-3902), and an A2 selective adenosine antagonist (KF17837) on the renal responses to CM. In sham-operated group, iohexol (2ml/kg/min for 3min) increased effective renal plasma flow (ERPF) and glomerular filtration rate (GFR), whereas in renal insufficiency group (with subtotal nephrectomy), following transient increases in ERPF and GFR, CM markedly decreased ERPF (-46.5 ± 6.7%) and GFR (-51.2 ± 7.1%). In sham-operated group, theophylline and KF17837 markedly attenuated CM-induced increases in ERPF and GFR, while KW-3902 had no effects on CM-induced increases in ERPF or GFR. In renal insufficiency group, initial increases in ERPF and GFR were blunted by theophylline and KF17837. In contrast, the subsequent decreases in ERPF and GFR were attenuated by theophylline (%ΔERPF, -12.2 ± 3.2% vs. -46.6 ± 6.7%, P < 0.01; %ΔGFR, 4.3 ± 2.5% vs. -51.0 ± 7.1%, P < 0.01), and were completely prevented by KW-3902 (%ΔERPF, 10.8 ± 2.9%; %ΔGFR, 23.8 ± 4.4%), whereas KF17837 aggravated ERPF (-73.3 ± 5.3%) and GFR (-78.4 ± 5.3%). These data indicate that in normal renal function, iohexol elicits renal vasodilation by activating mainly the adenosine A2 receptors. In contrast, in impaired renal function, CM induces both A2 and A1 activation; the former is associated with the initial renal vasodilation, while the latter is responsible for the sustained aggravation of renal hemodynamics

Efficacy of mizoribine pulse therapy in patients with rheumatoid arthritis who show a reduced or insufficient response to infliximab

The efficacy of infliximab, a chimeric antibody against tumor necrosis factor-α used to treat patients with rheumatoid arthritis (RA), tends to decrease as patients develop human antichimeric antibody against infliximab (HACA). The clinical study reported here was designed to evaluate the efficacy of mizoribine (MZR) pulse therapy in patients who show a reduced or insufficient response to infliximab. Ten RA patients who had active arthritis despite infliximab therapy were treated with MZR pulse therapy at a dose of 100 mg MZR and methotrexate (MTX) and the disease activity assessed at baseline and at weeks 4–8, 12–16, and 20–24. The dose was increased to 150 mg in those patients who showed an insufficient response to MZR. The mean 28-joint disease activity score (DAS28) at weeks 12–16 and 20–24 of therapy was significantly lower than that at baseline. A moderate or good European League against Rheumatism (EULAR) response was achieved in seven patients (70%) at weeks 12–16 and in five patients (50%) at weeks 20–24. The dose of 150 mg MZR was effective in one of the three patients who showed an insufficient response to pulse therapy with 100 mg MZR. Based on these results, we propose that MZR pulse therapy should be attempted before the patient is switched to other biologics

Gluteal-fold adipofascial perforator flap transposition for rectourethral fistula reconstruction

If a rectourinary fistula does not close spontaneously, it requires surgical closure. We present our experience of rectourethral fistula reconstruction using a gluteal-fold perforator flap, resulting in a successful outcome. The patient was a 64-year-old man with prostate cancer who underwent radical prostatectomy. However, he developed rectourinary fistula, which required surgical closure. A dissection was undertaken to divide the fistula tract, and the rectal and urethral defect were closed. A 12.0×3.0 cm gluteal-fold adipofascial perforator flap was harvested and placed in the space between the rectum and urethra. The viability of lap was favourable, without infection or necrosis. The patient could walk the next day, and was discharged 2 weeks later without fecaluria or liquid stool. We conclude that the gluteal-fold adipofascial perforator flap offers excellent functional advantages in rectourethral fistula reconstruction with minimal morbidity at the donor site

Chemoenzymatic Synthesis and Chemical Recycling of Poly(ester-urethane)s

Novel poly(ester-urethane)s were prepared by a synthetic route using a lipase that avoids the use of hazardous diisocyanate. The urethane linkage was formed by the reaction of phenyl carbonate with amino acids and amino alcohols that produced urethane-containing diacids and hydroxy acids, respectively. The urethane diacid underwent polymerization with polyethylene glycol and α,ω-alkanediols and also the urethane-containing hydroxy acid monomer was polymerized by the lipase to produce high-molecular-weight poly(ester-urethane)s. The periodic introduction of ester linkages into the polyurethane chain by the lipase-catalyzed polymerization afforded chemically recyclable points. They were readily depolymerized in the presence of lipase into cyclic oligomers, which were readily repolymerized in the presence of the same enzyme. Due to the symmetrical structure of the polymers, poly(ester-urethane)s synthesized in this study showed higher Tm, Young’s modulus and tensile strength values