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  • Author: Xia Qing x
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Abstract

In this work, the effect of flow rate of cooling water on interfacial heat transfer coefficient was studied using ZG230-450 and a newly designed modular water-cooled mold. The temperature profile of casting during the solidification process was first measured at different flow rates of cooling water. The measured temperature profile was then used to calculate the interfacial heat transfer coefficient (IHTC) of cast/water-cooled mold through solving the inverse heat conduction problem. Based on the calculated interfacial heat transfer coefficient, the effect of flow rate of cooling water on interfacial heat transfer coefficient was further analyzed. The results indicate that interfacial heat transfer coefficient increases with the increase of flow rate of cooling water. When the interfacial temperature of the casting exceeded 1500K, the interfacial heat transfer coefficient increased from 1000 to 1700 W/m2·K as the flow rate of cooling water increased from 2.6 to 5 m/s. As the interfacial temperature decreased, the difference in the interfacial heat transfer coefficient at different flow rates of cooling water also became lower, while a similar trend of IHTC versus flow rate of cooling water was observed. At the same flow rate, IHTC was larger at the early stage of solidification, following the formation of a solidification layer on the cast, IHTC first plummeted and then decreased more gradually. IHTC showed large variation during the cast solidification process.

Abstract

The potential of reduced-pressure radio-frequency air plasma (RFAP) in the modification of konjac glucomannan (KGM) was investigated. KGM film was exposed to 100 W RFAP for 50 s, 100 s, 150 s, 200 s, and 250 s, ground, and then subjected to various characterizations. Fourier Transform Infrared Spectroscopy (FTIR) revealed that RFAP treatment increased the content of –OH groups in KGM, with the lowest and highest rise occurring at the exposure durations 150 s and 250 s, respectively. RFAP radiation decreased the solubility of KGM at certain exposure durations, but slightly increased its thermal stability. Exposure to RFAP for 150 s and 250 s increased the hardness of the resultant KGM gel, but decreased the viscosity and elasticity of the KGM solution in a duration-dependent manner. Scanning Electron Microscope (SEM) observation revealed that RFAP treatment led to rougher surfaces and XRD (X-Ray Diffraction) analysis indicated the destroyed crystallinity of KGM. Hence, RFAP has potential application in the modification of KGM.

Abstract

The genus Neolitsea (Lauraceae) contains over 85 species distributed around the world. These plants have been found to be rich in sesquiterpenes, triterpenes, steroids, and alkaloids. This review summarizes the phytochemical progress and list of all the constituents isolated from the genus Neolitsea over the past few decades. Some biological activities of compounds isolated from this genus are also included.

Abstract

Severe acute pancreatitis (SAP) is a common disease with a poor prognosis. Heart failure is one cause of SAP patient death. Intermedin (IMD) is a potent endogenous cardio-protective substance. Administration of exogenous IMD showed beneficial effects in cardiovascular diseases. The aim of this study was to investigate the myocardial damage in SAP and to determine the therapeutic potential of IMD for SAP. Using an SAP rat model, we examined endogenous IMD expression following SAP induction, and determined the effect of IMD on myocardial function, histological morphology, apoptosis-related gene expression, and prognosis. Our results indicated that the cardiac function and histological structure were significantly disrupted in SAP rats. Infusion of exogenous IMD significantly preserved cardiac function and ameliorated myocardial damage. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) revealed that myocardial apoptosis was extensively present in SAP rats, and IMD infusion led to increased expression of the prosurvival factor Bcl-2, but decreased pro-apoptotic factors Bax and caspase-3. In addition, IMD infusion also reversed the change of IMD receptor systems in SAP rat heart tissue. Furthermore, we found that IMD infusion greatly decreased mortality of SAP rats. In conclusion, administration of SAP produced therapeutic effects in SAP through modulating apoptotic and pro-survival gene expression, inhibiting myocardial apoptosis, preserving cardiac function, and a useful therapeutic agent for SAP, and provides us an insight for a clinical trial of IMD for treating human severe acute pancreatitis.

Abstract

C36H40N4O17S2Zn, monoclinic, C2/c (no. 15), a = 16.690(3) Å, b = 22.905(2) Å, c = 12.940(2) Å, β = 124.849(6)°, V = 4059.6 Å3, Z = 4, Rgt(F) = 0.0473, wRref(F2) = 0.1327, T = 293 K.

Abstract

C22H30N2O4S2, monoclinic, P21/c, a = 13.6316(5) Å, b = 5.7462(2) Å, c = 14.1562(5) Å, β = 91.758(4)°, V = 1108.33(7) Å3, Z = 2, R gt (F) = 0.0464, wR ref (F 2 ) = 0.1249, T = 293 K.

Abstract

Two new mononuclear compounds [Mn(3-Br-pydc)(H2O)3] (1) and {[Mn(5-Br-pyc)(bipy)(H2O)(Cl)]·2H2O (2) (3-Br-H2pydc = 3-Br-pyridine-2,6-dicarboxylic acid, 5-Br-Hpyc = 5-Br-pyridine-2-carboxylic acid, bipy = 2,2′-bipyridine) have been synthesized by traditional solution reaction and hydrothermal reaction, respectively. In both compounds, the MnII center is six-coordinated in a distorted octahedral geometry, formed by one tridentate chelate 3-Br-pydc dianion and three water molecules in 1, while the coordination sphere consists of one bidentate chelate 5-Br-pyc anion, one bipy, one water molecule, and one chloride anion in 2 (MnNO5 for 1 and MnN3O2Cl for 2). O–H⋯O hydrogen bonds, Br⋯O halogen bonds, and/or π-π stacking assist in the construction of the three-dimensional (3D) network structures of 1 and 2. Notably, the 5-Br-Hpyc ligand was generated in situ by decarboxylation of the 3-Br-H2pydc precursor under hydrothermal conditions. Variable-temperature magnetic susceptibility data in the 2–300 K temperature range indicate weak antiferromagnetic coupling in both 1 and 2.

Abstract

The first part of this study investigated pattern recognition of head movements based on mechanomyography (MMG) signals. Four channel MMG signals were collected from the sternocleidomastoid (SCM) muscles and the splenius capitis (SPL) muscles in the subjects’ neck when they bowed the head, raised the head, side-bent to left, side-bent to right, turned to left and turned to right. The MMG signals were then filtered, normalized and divided using an unequal length segmentation algorithm into a single action frame. After extracting the energy features of the wavelet packet coefficients and the feature of the principal diagonal slices of the bispectrum, the dimension of the energy features were reduced by the Fisher linear discriminant analysis (FLDA). Finally, all the features were classified through the support vector machine (SVM) classifier. The recognition rate was up to 95.92%. On this basis, the second part of this study used the head movements to control a car model for simulating the control of a wheelchair, and the success rate was 85.74%.