Monascus-fermented grain vinegar enhances glucose homeostasis through the IRS-1/PI3K/Akt and AMPK signaling pathways in HepG2 cell and db/db mice

Food Science and Biotechnology - MV was reported to have beneficial effects in ameliorating insulin resistance in db/db mice, but the intrinsic mechanisms for glucose homeostasis are unclear. This...     

Tangeretin Ameliorates Glucose-Induced Podocyte Injury through Blocking Epithelial to Mesenchymal Transition Caused by Oxidative Stress and Hypoxia

Podocyte injury inevitably results in leakage of proteins from the glomerular filter and is vital in the pathogenesis of diabetic nephropathy (DN). The underlying mechanisms of podocyte injury facilitate finding of new therapeutic targets for DN treatment and prevention. Tangeretin is an O-polymethoxylated flavone present in citrus peels with anti-inflammatory and antioxidant properties. This study investigated the renoprotective effects of tangeretin on epithelial-to-mesenchymal transition-mediated podocyte injury and fibrosis through oxidative stress and hypoxia caused by hyperglycemia. Mouse podocytes were incubated in media containing 33 mM glucose in the absence and presence of 1–20 μM tangeretin for up to 6 days. The in vivo animal model employed db/db mice orally administrated with 10 mg/kg tangeretin for 8 weeks. Non-toxic tangeretin inhibited glucose-induced expression of the mesenchymal markers of N-cadherin and α-smooth muscle actin in podocytes. However, the reduced induction of the epithelial markers of E-cadherin and P-cadherin was restored by tangeretin in diabetic podocytes. Further, tangeretin enhanced the expression of the podocyte slit diaphragm proteins of nephrin and podocin down-regulated by glucose stimulation. The transmission electron microscopic images revealed that foot process effacement and loss of podocytes occurred in diabetic mouse glomeruli. However, oral administration of 10 mg/kg tangeretin reduced urine albumin excretion and improved foot process effacement of diabetic podocytes through inhibiting loss of slit junction and adherenes junction proteins. Glucose enhanced ROS production and HIF-1α induction in podocytes, leading to induction of oxidative stress and hypoxia. Similarly, in diabetic glomeruli reactive oxygen species (ROS) production and HIF-1α induction were observed. Furthermore, hypoxia-evoking cobalt chloride induced epithelial-to-mesenchymal transition (EMT) process and loss of slit diaphragm proteins and junction proteins in podocytes, which was inhibited by treating submicromolar tangeretin. Collectively, these results demonstrate that tangeretin inhibited podocyte injury and fibrosis through blocking podocyte EMT caused by glucose-induced oxidative stress and hypoxia.     

Floating-patch MEMS antennas on HRS substrate for millimetre-wave applications

Novel floating-patch micro-electro-mechanical system (MEMS) antennas are proposed for millimetre-wave applications. The floating-patch MEMS antennas are fabricated on a high resistivity silicon (HRS) substrate using surface micromachining technology. Simulation and experimental results for reflection coefficients and radiation patterns are presented.     

Determination of non-methane hydrocarbon emission factors from vehicles in a Tunnel in Seoul in May 2000

Measurements of non-methane hydrocarbons (NMHC) were performed at the entrance and exit of the Sangdo tunnel to estimate emission factors (EF) of NMHC from vehicles in May 2000. About 50 species were analyzed by a combined GC/FID and GC/MS system. Ethylene was the most abundant compound, followed by n-butane and acetylene, respectively. Based on the measurement data, the real world vehicular EF in Seoul was estimated. The highest EF value was 89.8 mg (veh-mile)^-1 for n-butane, followed by ethylene and toluene.     

Geometric origin of pair production by electric field in de sitter space

Particle production in de Sitter space provides an interesting model for understanding the curvature effect on Schwinger pair production by a constant electric field or the Schwinger mechanism on de Sitter radiation. For that purpose, we employ the recently introduced complex analysis method in which the quantum evolution in complex time explains pair production via the geometric transition amplitude and gives the pair-production rate as a contour integral. We compare the result from the contour integral with that of the phase-integral method.     

Solid extraction of caffeine and theophylline from green tea by molecular imprinted polymers

This paper involves a feasibility study on using molecular imprinted polymers as the sorbent materials in solid phase extraction for caffeine and theophylline from green tea. Two kinds of MIPs, with caffeine-theophylline mixture and pentoxifylline-theophylline mixture as the templates respectively, MAA as the monomer, EDMA as the crosslinker and ATBN as the initiator, were applied to this purpose. Mixture solution of caffeine and theophylline (1 Μg/ ml in acetonitrile) was applied to the solid extraction cartridges following a load, wash and elute procedure with acetonitrile, methanol, methanol-acetic acid (90/10, v/v) as the solvents, respectively. This solid phase extraction protocol was applied for extraction of caffeine and theophylline from green tea. Comparison between the results obtained with the MIPs cartridges and a traditional C₁₈ reversed-phase cartridge was made. It showed that the MIP-based sorbent on the solid phase extraction was comparable with that of C₁₈ material. HPLC analysis using a C₁₈ column (5 Μm, 250× 4.6 mm from Rstech corporation), methanol: water (60 :40, v/v) as the mobile phase at a flow rate of 0.6 ml/min was applied for the quantitative determination.     

Reactivity,chemical structure,and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state 13C CP/MAS NMR spectroscopy

This study was conducted to investigate the effects of reaction pH condition and hardener type on the reactivity, chemical structure, and molecular mobility of urea–formaldehyde (UF) resins. Three different reaction pH conditions, such as alkaline (7.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins, which were cured by adding four different hardeners (ammonium chloride, ammonium sulfate, ammonium citrate, and zinc nitrate) to measure gel time as the reactivity. FTIR and ¹³C‐NMR spectroscopies were used to study the chemical structure of the resin prepared under three different reaction pH conditions. The gel time of UF resins decreased with an increase in the amount of ammonium chloride, ammonium sulfate, and ammonium citrate added in the resins, whereas the gel time increased when zinc nitrate was added. Both FTIR and ¹³C‐NMR spectroscopies showed that the strong reaction pH condition produced uronic structures in UF resin, whereas both alkaline and weak‐acid conditions produced quite similar chemical species in the resins. The proton rotating‐frame spin–lattice relaxation time (T_1ρH) decreased with a decrease in the reaction pH of UF resin. This result indicates that the molecular mobility of UF resin increases with a decrease in the reaction pH used during its synthesis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2677–2687, 2003     

Preparation and characterization of thermoresponsive poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide) hydrogel materials for smart windows

In this study, a series of thermoresponsive cross-linked copolymer poly [N-isopropylacrylamide(NIPAm)-co-N-isopropylmethacrylamide(NIPMAm)] (P-M series samples: P-M-0, 10, 20, 30, 40, where numbers are co-monomer contents) hydrogels were prepared by free radical polymerization using the main monomer N-isopropylacrylamide (NIPAm), co-monomer N-isopropylmethacrylamide (NIPMAm), cross-linking agent N, N-methylenebisacrylamide, initiator (ammonium persulfate)/catalyst, and solvent water. In addition, a series of samples [P-G series samples: P-G-0, 10, 20, 30, 40, where numbers are co-solvent glycerol content) were prepared using P-M-40 as components and water/co-solvent glycerol as a mixed solvent. The effects of co-monomer NIPMAm and co-solvent glycerol contents on the lower critical solution temperature (LCST)/freezing temperature and light transmittance as function of temperature of the prepared copolymer gels were investigated. The resulting thermoresponsive polymer gels had LCSTs in the range of 17.9 to 38.7°C and freezing points in the range of 6.3 to −38.5°C. These gels are suitable materials for smart windows that are responsive to various environmental conditions.     

Residual strength prediction for aircraft panels with Multiple Site Damage,using the “EPFEAM” for stable crack growth analysis

In this paper, a new analytical method for solving stable crack propagation problems in a ductile panel with a row of cracks, is presented. The main purpose of the present study is to estimate the maximum load carrying capacity of such panels accurately. The so called Elastic Plastic Finite Element Alternating Method (Pyo et al. (1994) was extended to account for the propagating cracks. The crack propagation algorithm utilizes the analytic crack solution to release the stresses ahead the crack tip. The T _inf ^sup* integral is employed as the crack extension criterion. This integral parameter accounts for the near tip stress-strain singularity and its critical values for crack propagation can be extracted from the P-a curve of single cracked specimen case. The present method can be applied to the problems of the fuselage skin of aging airplanes, in which a row of cracks develop (MSD; Multiple Site Damage) from rivet holes. The load carrying capacity of such damaged structure reduces by a considerable amount. In order to predict the behavior near the critical load, one must account for plastic deformation, if the material is ductile. Furthermore, the maximum load carried by the structure is often reached after some amount of crack propagation. In this paper, a series of analyses have been conducted and their results compare with the available experimental data.     

An elastic-plastic finite element alternating method for analyzing wide-spread fatigue damage in aircraft structures

In this paper, a new analytical technique to study the effect of wide-spread fatigue damage in ductile panels is presented. The main purpose of the study is to develop an efficient methodology to predict the maximum load carrying capacity of panels with cracks. The problem arises especially in the fuselage skin of aging airplanes, in which cracks initiate from a row of rivet holes. This problem is known as Multi Site Damage (MSD) in aging aircraft. It is very important to estimate the load carrying capacity. Usually, the approach based on elastic fracture mechanics may overestimate the load capacity. It is very important for the aircraft structure with MSD to estimate the load carrying capacity of such damaged structures. Approaches based on elastic fracture mechanics often lead to a considerable error. In this paper, the Elastic Finite Element Alternating Method (EFEAM) has been extended to the case of elastic-plastic fracture of panels with MSD cracks. In EFEAM, analytical solutions to crack problems in an infinite plate are employed. In this study, we adopted an analytical solution for a row of cracks in an infinite panel. Furthermore, the plastic deformation is accounted for, by using the initial stress algorithm. The T _inf ^sup* integral is employed for the fracture criterion. The methodology developed in the present study can be called as Elastic-Plastic Finite Element Alternating Method (EPFEAM) for MSD problems. A series of studies on the maximum load capacity of panels with a row of cracks has been conducted.The support of this work by the Federal Aviation Administration through a grant to the Center of Excellence for Computational Modeling of Aircraft Structures, at the Georgia Institute of Technology, is sincerely appreciated.