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Xin-Gui Peng,Zhen Zhao,Di Chang,Yingying Bai,Qiuzhen Xu,Shenghong Ju 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.2
Objective: The purpose of the study was to non-invasively characterize and discriminate brown adipose tissue (BAT) from white adipose tissue (WAT) in rats using spectral computed tomography (CT) with histological validation. Materials and Methods: A lipid-containing phantom (lipid fractions from 0% to 100%) was imaged with spectral CT. An in vivo, non-enhanced spectral CT scan was performed on 24 rats, and fat concentrations of BAT and WAT were measured. The rats were randomized to receive intraperitoneal treatment with norepinephrine (NE) (n = 12) or saline (n = 12). Non-enhanced and enhanced spectral CT scans were performed after treatment to measure the elevation of iodine in BAT and WAT. The BAT/ aorta and WAT/aorta ratios were calculated and compared, after which isolated BAT and WAT samples were subjected to histological and uncoupling protein 1 (UCP1) analyses. Results: The ex-vivo phantom study showed excellent linear fit between measured fat concentration and the known gravimetric reference standard (r2 = 0.996). In vivo, BAT had significantly lower fat concentration than WAT (p < 0.001). Compared to the saline group, the iodine concentration of BAT increased significantly (p < 0.001) after injection of NE, while the iodine concentration of WAT only changed slightly. The BAT/aorta ratio also increased significantly after exposure to NE compared to the saline group (p < 0.001). Histological and UCP1 expression analyses supported the spectral CT imaging results. Conclusion: The study consolidates spectral CT as a new approach for non-invasive imaging of BAT and WAT. Quantitative analyses of BAT and WAT by spectral CT revealed different characteristics and pharmacologic activations in the two types of adipose tissue.
A cohesive zone model for self-similar fractal crack propagation
Chang Xin,Ren Mingfa,Guo Xu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10
Cracks in the nature have been proven to be fractal by many experiments. Despite the fractal fracture mechanics has been developed by many researchers, fractal geometry still has few applications in analysis of engineering structures. One of the reasons is that previous studies are somehow inconvenient when apply, e.g. to the finite element method. This study proposes a Cohesive zone model (CZM) for self-similar fractal crack propagation of material interfaces. The determination of the CZM parameters and the simulation of fractal crack propagation are developed by replace the fractal crack with the equivalent smooth crack. The fractal dimension has effects on both the crack extension resistance and the max traction stress. As shown by the simulation of a DCB specimen, the fractal dimension also affect the ultimate load and the crack propagation process. It is shown that it is possible to predict the propagation of fractal cracks without considering geometric modeling of the crack topology by our cohesive zone model.
Xin Xiong Chang,Nabisab Mujawar Mubarak,Shaukat Ali Mazari,Abdul Sattar Jatoi,Awais Ahmad,Mohammad Khalid,Rashmi Walvekar,E.C. Abdullah,Rama Rao Karri,M.T.H Siddiqui,Sabzoi Nizamuddin 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-
The concept of green chemistry has attracted attention due to the green synthesis and ecofriendly natureof the compounds leading to the green and sustainable chemical industries and processes. Chitosan is anecofriendly material, which is biodegradable, non-toxic, and biocompatible. It has the potential to bemodified into biofilms for various applications such as biomedical, packaging, and pharmaceutical fields. Nevertheless, some poor properties of chitosan restrict its wide applications. The incorporation ofnanocellulose fillers into chitosan matrix can enhance the mechanical and thermal properties of chitosan. Cellulose nanomaterials can be achieved through chemical and mechanical modifications. The commontype of nanocellulose are cellulose nanofibers (CNFs), cellulose nano-whiskers (CNWs), tunicate CNCs (t-CNCs), algae cellulose particles (AC) and bacterial cellulose particles (BC). Nanocellulose are applied asthe reinforcement fillers in various polymer matrices such as polysaccharides, proteins, lipids, polylacticacid etc. Deep eutectic solvents (DES) are relatively novel green solvents, which can be applied in variousfields. DES are widely applied in metal processing, polymer processing and synthesis. Even though thereare not much studies available on DES for synthesis of nanocomposite films; however they are used aseco-friendly solvents in manufacturing processes. This study reviews the discovery, structure, propertiesof chitosan and cellulose, their derivatives and applications. In addition, the paper also discusses theproperties of DES and their applications.