A novel semi-IPN hydrogel: Preparation, swelling properties and adsorption studies of Co (II)

Xiaohong Wang,Haiqian Hou,Yujun Li,Yingying Wang,Chen Hao,Cunwang Ge b 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.41 No.-

A range of super-absorbent semi-IPN hydrogels—polyvinyl alcohol/poly (acrylic acid-co-acrylic amide)(PVA-P(AA-co-AM)) were synthesized via free radical polymerization method under ultrasound-assistedcondition. L16 (45) orthogonal experiments were designed to optimize the synthesis conditions and thesuccess was characterized by FTIR, SEM and TGA. Swelling capacities were studied in various pH solutionand saline solution whose results indicated that pH in solution shows an obvious influence on it and thesalt resistance is greater in salt solution of low valence relative to that of high valence. Meanwhile, itsswelling behavior was evaluated in water solution, which revealed that the swelling process conformedto the Schott model and the diffusion type was non-Fickian diffusion. Moreover, the adsorption on cobalt(II) from aqueous solutions was also investigated in the paper. The optimumpH value was found close to4 for the cobalt (II) adsorption and it was discovered that adsorption kinetics and adsorption isothermsfor cobalt (II) were in accordance with the pseudo-second-order model and the Freundlich modelrespectively. Besides, thermodynamic parameters were calculated for the cobalt (II) adsorption and thefindings revealed that the adsorption behavior is spontaneous and endothermic.

Intracranial Artery Calcifcation and Its Clinical Signifcance

Xiaohong Wu,Xiang-Yan Chen,Li Juan Wang,Ka Sing Wong 대한신경과학회 2016 Journal of Clinical Neurology Vol.12 No.3

Intracranial arterial calcifcation (IAC) is an easily identifable entity on plain head computed tomography scans. Recent studies have found high prevalence rates for IAC worldwide, and this may be associated with ischemic stroke and cognitive decline. Aging, traditional cardiovascular risk factors, and chronic kidney disease have been found to be associated with IAC. Te severity of IAC can be assessed using diferent visual grading scales or various quantitative methods (by measuring volume or intensity). An objective method for assessing IAC using consistent criteria is urgently required to facilitate comparisons between multiple studies involving diverse populations. Tere is accumulating evidence from clinical studies that IAC could be utilized as an indicator of intracranial atherosclerosis. However, the pathophysiology underlying the potential correlation between IAC and ischemic stroke—through direct arterial stenosis or plaque stability—remains to be determined. More well-designed clinical studies are needed to explore the predictive values of IAC in vascular events and the underlying pathophysiological mechanisms.

Musca domestica Pupae Lectin Improves the Immunomodulatory Activity of Macrophages by Activating Nuclear Factor-jB

Xiaohong Cao,Minghui Zhou,Chunling Wang,Lihua Hou,Yuanyuan Li,Linye Chen 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.2

In this study, Musca domestica pupae lectin (MPL) was screened for its immunomodulatory effect on macrophages. The phagocytosis of macrophages was improved significantly when they were treated with MPL: remarkable changes were observed in the morphology of the cells, the metabolic abilities of DNA and RNA were enhanced, and the production of hepatin was increased. Meanwhile, compared with the control group, not only the mRNA expressions of tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), and interferon-c (IFN-c) in macrophages, but also the productions of proteins,were strongly induced by MPL; these effects were inhibited by pyrrolidine dithiocarbamate. Further study suggested that MPL could increase the nuclear factor-jB (NF-jB) p65 level in the nucleus. Overall, these results indicate that the improving immunomodulatory activity induced by MPL is mainly due to the increasing productions of TNF-a, IL-6, and IFN-c and that the activation of macrophage by MPL is partly mediated via the NF-jB pathway.

A Novel Approach Based on Fault Tolerance and Recursive Segmentation to Query by Humming

Xiaohong Yang,Qingcai Chen,Xiaolong Wang 보안공학연구지원센터 2010 International Journal of Hybrid Information Techno Vol.3 No.3

Regional Brain Activity During Rest and Gastric Water Load in Subtypes of Functional Dyspepsia: A Preliminary Brain Functional Magnetic Resonance Imaging Study

Yanwen Chen,Ruifeng Wang,Bo Hou,Feng Feng,Xiucai Fang,Liming Zhu,Xiaohong Sun,Zhifeng Wang,Meiyun Ke 대한소화기 기능성질환∙운동학회 2018 Journal of Neurogastroenterology and Motility (JNM Vol.24 No.2

Background/Aims Functional dyspepsia (FD) remains a great clinical challenge since the FD subtypes, defined by Rome III classification, still have heterogeneous pathogenesis. Previous studies have shown notable differences in visceral sensation processing in the CNS in FD compared to healthy subjects (HS). However, the role of CNS in the pathogenesis of each FD subtype has not been recognized. Methods Twenty-eight FD patients, including 10 epigastric pain syndrome (EPS), 9 postprandial distress syndrome (PDS), and 9 mixed-type, and 10 HS, were enrolled. All subjects underwent a proximal gastric perfusion water load test and the regional brain activities during resting state and water load test were investigated by functional magnetic resonance imaging. Results For regional brain activities during the resting state and water load test, each FD subtype was significantly different from HS (P < 0.05). Focusing on EPS and PDS, the regional brain activities of EPS were stronger than PDS in the left paracentral lobule, right inferior frontal gyrus pars opercularis, postcentral gyrus, precuneus, insula, parahippocampal gyrus, caudate nucleus, and bilateral cingulate cortices at the resting state (P < 0.05), and stronger than PDS in the left inferior temporal and fusiform gyri during the water load test (P < 0.05). Conclusions Compared to HS, FD subtypes had different regional brain activities at rest and during water load test, whereby the differences displayed distinct manifestations for each subtype. Compared to PDS, EPS presented more significant differences from HS at rest, suggesting that the abnormality of central visceral pain processing could be one of the main pathogenesis mechanisms for EPS.

Green and Efficient Synthesis of an Adsorbent Fiber by Plasma-induced Grafting of Glycidyl Methacrylate and Its Cd(II) Adsorption Performance

Haonan Chen,Mulin Guo,Xiaohong Yao,Zhengwei Luo,Kai Dong,Zhouyang Lian,Wuji Wei 한국섬유공학회 2018 Fibers and polymers Vol.19 No.4

A new chelating adsorbent for the removal of Cd(II) from aqueous solution, PP-g-GMA-DETA fibers, is prepared by plasma induced grafting of glycidyl methacrylate (GMA) onto the surface of polypropylene (PP) fibers, followed by modification with diethylenetriamine (DETA). The effects of grafting parameters on the grafting degree are investigated. Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy prove the successful grafting of GMA onto the surfaces of PP fibers and the subsequent conversion of epoxy groups of grafted GMA to amine groups, on reaction with DETA. The adsorption performances of Cd(II) by the chelating fibers are evaluated in detail. Kinetic and isothermal parameters are also evaluated. The data fit well with the pseudo-second order and Langmuir isotherm model, respectively. The maximum adsorption capacity of Cd(II) is 46.47 mg g-1 and the prepared fibers show selective adsorbability towards target Cd(II) in presence of competing Mg(II) ions.

Z-domain modeling of peak current mode control for full-bridge DC-DC buck converters

Wang, Xiaohong,Huang, Qisong,Zhang, Bo,Chen, Di,Guan, Quanxue The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

Traditional local-averaged state-space modeling for peak current mode (PCM) controls fails to explain the subharmonic oscillation phenomenon when the spectrum is higher than half of the switching frequency. To address this problem, this paper presents a small-signal modeling method in the z-domain, and builds a discrete linear model for the current loop of a full-bridge DC-DC converter. This discrete model is converted into a second-order continuous model that is able to represent the system performance with a wider frequency range. A frequency-domain analysis shows that this model can be used to explain the subharmonic oscillations and unstable characteristics. This provides an engineering guideline for the practical design of slope compensation. The effectiveness of the proposed modeling method has been verified by simulation and experimental results with a prototype working in the Buck mode.

Ozone infusiblization and curing mechanism of polysilazane ceramic precursor fibers

Li Xiaohong,Luo Xiaoyu,Li Jing,Li Jinxia,Yang Jiahao,Ahmad Zahoor,Bao Zhihao,Zhang Xiao,Chen Jianjun 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.5

An appropriate infusible method plays a vital role as one of the key processes of the fabrication of polymer-derived ceramic fibers. In this work, ozone curing, a novel room temperature controllable curing strategy was used to prepare SiCN ceramic fibers. Some circular pores were observed on the surface of the obtained SiCN ceramic fibers. The tensile strength of the fibers was also investigated. To reveal the ozone-curing mechanisms of the PSZ fibers and the formation process of the circular pores, the FT-IR, SEM, OM, XRD and TG were characterized. The results showed that the Si–H bonds and Si-CH3 groups in the PSZ molecule were oxidized gradually to form oxygen-containing groups such as Si–OH, Si–O-Si and C = O in the ozone curing process, which contributed to the curing and weight gain of the PSZ fibers. Moreover, a hydrolysis reaction between Si-NH-Si and H2O might further accelerate the curing of the PSZ fibers. An unexpected result of the hydrolysis reaction is the formation of some circular pores on the surface layer of the PSZ fibers. This strategy provides a method to design, adjust and control the microstructure and composition of silicon-based ceramic fibers, and the obtained SiCN fibers may be used as catalyst support, bacterial culture and other fields.

Influence of Laser Power on Grain Size and Tensile Strength of 5A90 Al–Li Alloy T-joint Fabricated by Dual Laser-Beam Bilateral Synchronous Welding

Shuai Chen,Xiaohong Zhan,Yanqiu Zhao,Youfa Wu,Dongtao Liu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

Dual laser-beam bilateral synchronous welding is introduced to produce the 2.5 mm thick 5A90 Al–Li alloy T-joint. Thegrain morphology and grain size of weld metal (WM) in the T-joint are analyzed and calculated. The tensile experiment,scanning electron microscopy and energy disperse spectroscopy are respectively employed to study the tensile strength,fracture morphology and chemical composition of the T-joint. The results reveal that when the laser power is increased from2500 to 3000 W, the grain sizes of fine-grained layers and columnar dendrites near the fusion line are significantly reduced. Conversely, that of equiaxed dendrites at the WM center is not sensitive to the variety of laser power. Moreover, the degreeof elemental segregation in WM near the fusion line is also aggravated with the increasing of the laser power. The tensilestrength of the T-joint with the laser power of 2500 W is significantly higher than that with the laser power of 3000 W. Thetensile fracture locations are occurred in the weld toe with obvious pores, shear dimples and tear ridges, which are the typicalcharacteristics of ductile fracture. Besides, the chemical compositions of the second phase particles in the WM are moresensitive to than the variation of laser power compared with that of the matrix.

Morphology Evolution of Mn5Si3 Phase and Effect of Mn content on Wear Resistance of Special Brass

Lifu Bie,Xiaohong Chen,Ping Liu,Tao Zhang,Xiangliu Xu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.4

There is a surge of interests in developing newer materials with special properties and many areas are being explored byseveral groups. We wish to report our findings on the effect of Mn content on the microstructure and tribological behaviorof special brass. With the increase of Mn content in the range of 4–10 wt%, the hardness and wear resistance of the specialbrass were all changed, and the adhesion with abrasion is form the friction behavior, mainly for all brasses. It was observedthat the matrix grain size was the smallest, and the hard phase was precipitated the most when the Mn quantity attained the8 wt% mark. During this period, the brass has the highest hardness and best wear resistance, which results from the grainrefinement and load transferring effect of precipitates. It was characterized by SEM, EDS, XRD, TEM, etc., and the resultsconfirmed that the precipitates were Mn5Si3and its structure was hollow hexagonal prism. The morphology evolution of thehard phase and its growth mechanism have been investigated, analyzed and simulated the nucleation and growth process ofthe Mn5Si3phase based on crystallography. The outcomes also showed that the presence of defects on the {0001} faces wasthe crucial factor for one-dimensional elongated structure of Mn5Si3phase.