Parametric study of non-periodic and hybrid auxetic bending-active gridshells

This paper presents a design method of Auxetic Bending-Active Gridshells (ABAGs), which are curved surfaces generated from the initial flat grid with 2-dimensional auxetic patterns. One of the mechanical properties of ABAGs is that a dome-like shape of a curved surface can be easily obtained by bending a grid due to negative Poisson's ratio for in-plane deformation. Shapes of auxetic patterns are relevant to Poisson's ratio. Non-periodic and/or hybrid 2-dimensional auxetic patterns are developed for designing the initial flat grid of ABAGs. Shape parameters are the sizes of each plane unit for tuning its reentrant pattern, and two types of reentrant shapes are mixed on an initial flat grid. Using the non-uniform patterns, we can obtain an asymmetric and more complex free-form surface of ABAGs than those composed of a uniform reentrant pattern. Discrete Gaussian curvature at each node on a curved surface is computed for quantitatively evaluating the properties of shapes of the obtained surfaces. Possibility of ABAGs as a new design tool is demonstrated by showing that various shapes are generated through large deformation analysis with the forced displacements at the supports

A 3-dimensional elastic beam model for form-finding of bending-active gridshells

This research is partly supported by SPIRITS program 2017 of Kyoto University.In this paper, we present a 3-dimensional elastic beam model for the form-finding and analysis of elastic gridshells subjected to bending deformation at the self-equilibrium state. Although the axial, bending, and torsional strains of the beam elements are small, the curved beams connected by hinge joints are subjected to large-deformation. The directions and rotation angles of the unit normal vectors at the nodes of the curved surfaces in addition to the translational displacements are chosen as variables. Based on the 3-dimensional elastic beam model, deformation of an element is derived from only the local geometrical relations between the orientations of elements and the unit normal vectors at nodes without resorting to a large rotation formulation in the 3-dimensional space. Deformation of a gridshell with hinge joints is also modeled using the unit normal vectors of the surface. An energy-based formulation is used for deriving the residual forces at the nodes, and the proposed model is implemented within dynamic relaxation method for form-finding and analysis of gridshells. The accuracy of the proposed method using dynamic relaxation method is confirmed in comparison to the results by finite element analysis. The results are also compared with those by optimization approach for minimizing the total potential energy derived using the proposed formulation

Recent Topics in the Studies of Laboratory of Nutrition, Tohoku University : Newly Clarified Function of Vitamin K

Vitamin K (VK) is essential for blood coagulation and bone metabolism in mammals as a Gla-protein activating factor, i.e., VK acts as a cofactor in the posttranslational synthesis of γ-carboxyglutamic acid (Gla) from glutamic acid (Glu) residues in the nascent proteins. Menaquinone-4 (MK-4) is one of the VK_2 analogues, and is well known to have bioactivity in the suppression of bone resorption through apoptosis of osteoclast cells, thus MK-4 is now also used clinically as a therapeutic drug for the osteoporosis. Besides of these well-known functions, MK-4 is strongly presumed to have other novel functions because we have gradually recognized that MK-4 accumulates in various tissues of germfree animals fed an MK-4-free diet. Accordingly, we have focused on clarification of the mechanism of MK-4 formation in several tissues, using both in vitro tissue homogenates (bovine, rats, mice, chicken) and in vivo experiments with rats and mice. To elucidate the biological role of MK-4 production, we used germfree rats to eliminate MK-n synthesized by intestinal flora. Our in vivo results indicate that MK-4 is produced in diverse tissues from ingested vitamin K analogues, including vitamin K_1, MK-n (MK-6, MK-7, and MK-10); and VK_3 without enzymatic participation of microorganisms in the intestine. In addition to the liver and bone, VK is found in the brain, heart, testis, kidney, pancreas and salivary glands mainly as menaquinone-4 (MK-4). However, the physiological role of MK-4 in these various organs has not been fully understood yet. In the present study we identified genes of which expression is changed in testis under vitamin K deficient condition using DNA microarray. The genes involved in the biosynthesis pathway of cholesterol and steroid hormone were decreased in vitamin K deficient group. The amount of Cyp11a (P450scc) mRNA, rate-limiting enzyme for testosterone synthesis, was positively correlated with the concentration of MK-4 in testis. Moreover, the concentration of testosterone in plasma and testis was decreased in vitamin K deficient group compared with the control and vitamin K supplemented groups. These results suggests that vitamin K is involved in steroid production in testis through the regulation of Cyplla

Menaquinone-4 enhances testosterone production in rats and testis-derived tumor cells

<p>Abstract</p> <p>Background</p> <p>Vitamin K is essential for the posttranslational modification of various Gla proteins. Although it is widespread in several organs, including the testis, the function of vitamin K in these organs is not well characterized. In this study, we investigated the function of vitamin K in the testis and analyzed its role in steroidogenesis.</p> <p>Methods</p> <p>Eight-week-old male Wistar rats were fed a diet supplemented with menaquinone-4 (MK-4, 75 mg/kg diet), one of the predominant K₂vitamins present in the testis, for 5 weeks. <it>In vivo </it>testosterone levels of the rats' plasma and testes were measured by enzyme-linked immunosorbent assay, and <it>in vitro </it>testosterone levels of testis-derived tumor cells (I-10 cells) maintained in Ham's F-10 medium with 10% fetal bovine serum were measured following treatment with MK-4 (0 to 100 μM) at several time points. Testosterone and cellular protein levels were analyzed with respect to their effects on steroidogenesis.</p> <p>Results</p> <p>Testosterone levels in the plasma and testes of MK-4-fed rats were significantly increased compared to those of control rats, with no obvious differences in plasma luteinizing hormone levels. Secreted testosterone levels from I-10 cells were elevated by MK-4, but not by vitamin K₁, in a dose-dependent manner independent of cAMP treatment. Western blot analysis revealed that expression of CYP11A, the rate-limiting enzyme in steroidogenesis, and phosphorylation levels of protein kinase A (PKA) and the cAMP response element-binding protein were all stimulated by the presence of MK-4. Enhancement of testosterone production was inhibited by H89, a specific inhibitor of PKA, but not by warfarin, an inhibitor of γ-glutamylcarboxylation.</p> <p>Conclusions</p> <p>MK-4 stimulates testosterone production in rats and testis-derived tumor cells via activation of PKA. MK-4 may be involved in steroidogenesis in the testis, and its supplementation could reverse the downregulation of testosterone production in elders.</p

Handheld magnetic probe with permanent magnet and Hall sensor for identifying sentinel lymph nodes in breast cancer patients

Abstract The newly developed radioisotope-free technique based on magnetic nanoparticle detection using a magnetic probe is a promising method for sentinel lymph node biopsy. In this study, a novel handheld magnetic probe with a permanent magnet and magnetic sensor is developed to detect the sentinel lymph nodes in breast cancer patients. An outstanding feature of the probe is the precise positioning of the sensor at the magnetic null point of the magnet, leading to highly sensitive measurements unaffected by the strong ambient magnetic fields of the magnet. Numerical and experimental results show that the longitudinal detection length is approximately 10 mm, for 140 μg of iron. Clinical tests were performed, for the first time, using magnetic and blue dye tracers—without radioisotopes—in breast cancer patients to demonstrate the performance of the probe. The nodes were identified through transcutaneous and ex-vivo measurements, and the iron accumulation in the nodes was quantitatively revealed. These results show that the handheld magnetic probe is useful in sentinel lymph node biopsy and that magnetic techniques are widely being accepted as future standard methods in medical institutions lacking nuclear medicine facilities

Effects of household-scale cooking on volatile compounds, sensory profile, and hypotensive effect of Kenikir (<i>Cosmos caudatus</i>)

Kenikir (Cosmos caudatus) can be used in the preparation of raw and cooked vegetables in some Indonesian dishes. The cooking process may affect the appearance, chemical properties, and flavor of kenikir. This study aims to determine the effect of household scale cooking on the volatile compounds, sensory profiles, and hypotensive activity of kenikir. Fresh kenikir samples and samples boiled or steamed at 100 ℃ (for 3 and 5 minutes) were analyzed for volatile compounds compositions (solid-phase microextraction-Gas chromatography-mass spectrometry, SPME-GCMS), sensory profiles by free choice profiling, and in-vivo study by using stroke-prone spontaneously hypertensive rats (SHRSP)—a model of spontaneous hypertension. The GCMS analysis identified 30 volatile compounds from 5 compound groups, namely alcohols (2 compounds), benzenes (3 compounds), esters (3 compounds), monoterpenes (10 compounds), and sesquiterpenes (12 compounds). Several compounds, namely (Z)-3-hexenol, α-cadinol, and 3-carene were only detected in fresh kenikir, whereas β-myrcene and β-elemene compounds were only identified after cooking. The principal component analysis of sensory attributes associated fresh kenikir with bright color and minty taste, steamed kenikir with floral aroma, and boiled kenikir with juicy, moist, tender, and smooth texture. Furthermore, a hypotensive effect was shown in the water extract of kenikir after 2 and 4 hours of single oral administration in SHRSP. In summary, the heating process (boiled and steamed) of kenikir has changed its volatile compound composition, which can affect its sensory profiles. In addition, the water extract of kenikir can diminish hypertension in SHRSP

Losartan modulates muscular capillary density and reverses thiazide diuretic-exacerbated insulin resistance in fructose-fed rats

The renin–angiotensin system (RAS) is involved in the pathogenesis of insulin sensitivity (IS). The role of RAS in insulin resistance and muscular circulation has yet to be elucidated. Therefore, this study sought to determine the mechanisms of angiotensin II receptor blockers (ARBs) and/or diuretics on IS and capillary density (CD) in fructose-fed rats (FFRs). Sprague-Dawley rats were fed either normal chow (control group) or fructose-rich chow for 8 weeks. For the last 4 weeks, FFRs were allocated to four groups: an FFR group and groups treated with the thiazide diuretic hydrochlorothiazide (HCTZ), with the ARB losartan, or both. IS was evaluated by the euglycemic hyperinsulinemic glucose clamp technique at week 8. In addition, CD in the extensor digitorum longus muscle was evaluated. Blood pressure was significantly higher in the FFRs than in the controls. HCTZ, losartan and their combination significantly lowered blood pressure. IS was significantly lower in the FFR group than in the controls and was even lower in the HCTZ group. Losartan alone or combined with HCTZ significantly increased IS. In all cases, IS was associated with muscular CD, but not with plasma adiponectin or lipids. These results indicate that losartan reverses HCTZ-exacerbated insulin resistance, which can be mediated through the modulation of muscular circulation in rats with impaired glucose metabolism

Optimization method for shape design of Auxetic Bending-Active Gridshells using discrete differential geometry

The purpose of this paper is to propose an optimization method for shape design of Auxetic Bending-Active Gridshells (ABAGs). A 2-dimensional auxetic structure has negative Poisson’s ratio for in-plane deformation. Positive Gaussian curvature distributed on a curved surface of ABAG is obtained by out-of-plane deformation of the initial flat grid composed of reentrant structural units. We introduce discrete differential geometry into shape design of the surface of ABAG, which can be easily discretized into triangular meshes in accordance with the discrete member locations. The objective function of the proposed optimization problem is formulated using discrete Gaussian curvature, which is defined as the angle defect at node. In addition, discrete mean curvature vector is used for specifying the direction of convexity. We use particle swarm optimization for solving the problem. It is shown in the numerical examples, that surfaces with specified distribution of convex region on an ABAG can be obtained using the proposed method