Numerical Study on Characteristics of Stress in Ω-Shaped Tubular Bellows

Tubular bellows is a mechanical device for absorbing energy or displacement in structures. It is widely used to deal with vibrations, thermal expansion, and the angular, radial, and axial displacements of components. In the present study, the characteristics of stress in Ω-shaped tubular bellows are studied numerically. An Ω-shaped of tubular bellows available in market is subjected to internal pressure and deflection loads. The stresses are compared with the conventional U-shaped bellows. Elastic analyses of a two-dimensional, axisymmetric model with structural solid elements were carried out. A full convolution of each bellow was modeled. The dimensions of the bellows are as follows: ri_i = 64mm, r_0 = 77mm, q = 11.5 mm, and thickness t = 0.45mm. The bellows are made of SUS321 with properties of E = 193 GPa and υ = 0.3. The numerical results show good agrement with analytical results. The distributions of axial stresses are plotted for each bellows. It was concluded that the most destructive stress in bellows was meridional bending stress. The meridional bending stress in Ω-shaped of tubular bellows are lower than the U-shaped ones but higher than in toroidal bellows.特集 : Special Section for the Papers Presented at the Symposium on Mechanical Engineering, Industrial Engineering, and Robotics held at Noboribetsu, Hokkaido, Japan on 11 - 12 January 201

ステンレス・フレキシブルチューブの健全性評価

平成23年度 プレ共同研究成

Co-activation of macrophages and T cells contribute to chronic GVHD in human IL-6 transgenic humanised mouse model.

BACKGROUND: Graft-versus host disease (GVHD) is a complication of stem cell transplantation associated with significant morbidity and mortality. Non-specific immune-suppression, the mainstay of treatment, may result in immune-surveillance dysfunction and disease recurrence. METHODS: We created humanised mice model for chronic GVHD (cGVHD) by injecting cord blood (CB)-derived human CD34 FINDINGS: In cGVHD humanised mice, we found activation of T cells in the spleen, lung, liver, and skin, activation of macrophages in lung and liver, and loss of appendages in skin, obstruction of bronchioles in lung and portal fibrosis in liver recapitulating cGVHD. Acute GVHD humanised mice showed activation of T cells with skewed TCR repertoire without significant macrophage activation. INTERPRETATION: Using humanised mouse models, we demonstrated distinct immune mechanisms contributing acute and chronic GVHD. In cGVHD model, co-activation of human HSPC-derived macrophages and T cells educated in the recipient thymus contributed to delayed onset, multi-organ disease. In acute GVHD model, mature human T cells contained in the graft resulted in rapid disease progression. These humanised mouse models may facilitate future development of new molecular medicine targeting GVHD

Cholinergic Modulation of Narcoleptic Attacks in Double Orexin Receptor Knockout Mice

To investigate how cholinergic systems regulate aspects of the sleep disorder narcolepsy, we video-monitored mice lacking both orexin (hypocretin) receptors (double knockout; DKO mice) while pharmacologically altering cholinergic transmission. Spontaneous behavioral arrests in DKO mice were highly similar to those reported in orexin-deficient mice and were never observed in wild-type (WT) mice. A survival analysis revealed that arrest lifetimes were exponentially distributed indicating that random, Markovian processes determine arrest lifetime. Low doses (0.01, 0.03 mg/kg, IP), but not a high dose (0.08 mg/kg, IP) of the cholinesterase inhibitor physostigmine increased the number of arrests but did not alter arrest lifetimes. The muscarinic antagonist atropine (0.5 mg/kg, IP) decreased the number of arrests, also without altering arrest lifetimes. To determine if muscarinic transmission in pontine areas linked to REM sleep control also influences behavioral arrests, we microinjected neostigmine (50 nl, 62.5 µM) or neostigmine + atropine (62.5 µM and 111 µM respectively) into the nucleus pontis oralis and caudalis. Neostigmine increased the number of arrests in DKO mice without altering arrest lifetimes but did not provoke arrests in WT mice. Co-injection of atropine abolished this effect. Collectively, our findings establish that behavioral arrests in DKO mice are similar to those in orexin deficient mice and that arrests have exponentially distributed lifetimes. We also show, for the first time in a rodent narcolepsy model, that cholinergic systems can regulate arrest dynamics. Since perturbations of muscarinic transmission altered arrest frequency but not lifetime, our findings suggest cholinergic systems influence arrest initiation without influencing circuits that determine arrest duration

Antimicrobial Activity of Protamine-Loaded Calcium Phosphates against Oral Bacteria

Protamine is an antimicrobial peptide extracted from fish. In this study, we loaded protamine onto dicalcium phosphate anhydride (DCPA), a dental material. Protamine was loaded by stirring DCPA into a protamine solution. To explore the antimicrobial activity of the materials, we cultivated Streptococcus mutans on fabricated discs for 24 h. When S. mutans was cultivated on the discs under no sucrose conditions, the loaded protamine was not released, and the ratio of dead bacteria increased on the surface of P (125) DCPA (half of the saturated level of protamine (125 ppm protamine) was loaded). Aside from P (500) DCPA (saturated level of protamine was loaded), some protamine was released, and the number of planktonic bacteria in the supernatant decreased. Using medium containing 1% sucrose, the release of protamine was promoted from P (125) DCPA due to lowered pH. However, lowering of the pH decreased the antimicrobial activity of protamine. On the other hand, P (500) DCPA released protamine before the pH was lowered, and biofilm formation was inhibited. The loaded protamine expressed antimicrobial activity, both on the surface of the materials and in the surrounding environment. The interaction of loaded protamine with calcium phosphates could promote the application of protamine in the dental field