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Extended Airtime Fair Scheduling Method for a Zigbee Network
Van-Tu Chau,T.T. Quyen Bui,Anh-Tuan Do,Quang-Vinh Thai 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10
In a Zigbee network, when many nodes simultaneously send data packets to a Zigbee coordinator through routes (branches), the Zigbee coordinator cannot deal with all signals. Interference and noises are existed during data transmission. This problem is still one of challenges in the network communication. In this paper, we propose an extended airtime fair algorithm in which throughput of a Zigbee network is maximized and fractions of airtime are taken into account. We adapt a utility function that is proposed by Kelly (1997) in maximizing the network throughput; nevertheless, throughput of each branch is multiplied by a fraction of airtime. Fractions of airtime play a role in creating a balance of throughputs of branches: the throughput and fairness of each branch is guaranteed. Moreover, the usefulness of our proposed algorithm for a Zigbee network is presented; simulation results show that the throughput and fairness are better than those of a case of not using airtime fair.
Van Thanh, Nguyen,Jang, Hyun-Jae,Vinh, Le Ba,Linh, Kieu Thi Phuong,Huong, Phan Thi Thanh,Cuong, Nguyen Xuan,Nam, Nguyen Hoai,Van Minh, Chau,Kim, Young Ho,Yang, Seo Young Elsevier 2019 Bioorganic chemistry Vol.88 No.-
<P><B>Abstract</B></P> <P>In a search for anti-inflammatory activity in resources from Vietnamese mangroves, we found that a methanolic extract from the leaves of <I>Calophyllum inophyllum</I> (CIL) showed significant anti-inflammatory effects <I>in vitro</I>. Using various chromatographic techniques, we subsequently isolated 12 compounds (<B>1</B>–<B>12</B>) from a methanolic extract of CIL, including two novel compounds (<B>1</B>–<B>2</B>). The inhibitory effects of these compounds on lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 cells were also evaluated. Compound <B>1</B> significantly suppressed NO production (IC<SUB>50</SUB> = 2.44 ± 0.88 µM), the secretion of pro-inflammatory cytokines (including interleukin-1 beta and tumor necrosis factor alpha), and the expression of inducible nitric oxide synthase through downregulation of nuclear factor-kappa-B signaling cascades. These results suggest that <I>C. inophyllum</I> leaves might be a useful resource for the development of drugs for the treatment of inflammation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Twelve compounds were isolated from Vietnamese mangrove <I>Calophyllum inophyllum</I>. </LI> <LI> Two new compounds <B>1</B> and <B>2</B> were determined by spectroscopic methods. </LI> <LI> Compound <B>1</B> showed significant anti-inflammatory activity. </LI> <LI> These results suggested that <I>C. inophyllum</I> might useful as the anti-inflammation drug. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Effect of hydrothermal time on the structure and property of graphene oxide membrane
Tran Van Khai,Pham Thuy Trang,Le Ngoc Long,Le Van Thang,Tran Duc Chau,Vuong Vinh Dat,Mai Thanh Phong 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4
Two dimensional graphene oxide (GO) has potential application in membrane separation owing to its unique structure andphysicochemical properties. In this study, the reduced graphene oxide (rGO) was synthesized from GO via hydrothermaltreatment at 160 oC for 1, 2, 3 and 4 h, and the rGO membranes were prepared on cellulose nitrate supporting membranesby vacuum filtration. The structural change and chemical composition of GO were investigated using X-ray diffraction (XRD),Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM),atomic force microscopy (AFM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) andcontact angle measurements. The result shows that uniformly intact rGO membranes with good hydrophobicity could beachieved by adjusting the reduction degree of GO through changing the hydrothermal reaction time. The huge improvementof the hydrophobic property of rGO could be attributed to the removal of the most the hydrophilic oxygen-containingfunctional groups on the surface of GO. Additionally, the structure, chemical composition, and d-spacing of the GO can alsobe controlled by adjusting the reduction time. This method holds great potential because it can be prepared in large quantitiesat low cost, and suitable for applications in membrane technologies.
Duong Bich Thuy,Duong Minh Cuong,Campbell James,Nguyen Van Minh Hoang,Nguyen Huu Hien,Bui Thi Bich Hanh,Nguyen Van Vinh Chau,McLaws Mary-Louise 대한감염학회 2021 Infection and Chemotherapy Vol.53 No.3
Little is known about antibiotic-resistant Gram-negative bacteria (GNB) intestinal carriage among healthcare workers (HCWs) in Vietnam. All HCWs at a tertiary intensive care units were asked to undertake weekly rectal swabs. Among 40 participants, 65% (26/40) carried extended spectrum β-lactamases (ESBL)/AmpC β-lactamase-producing Escherichia coli. Two HCWs colonized with ESBL/AmpC β-lactamase-producing Klebsiella pneumoniae. One HCW colonized with Acinetobacter baumannii. No one carried Pseudomonas spp.. A quarter (10/40) of HCWs were identified as persistent and frequent carriers. There is an urgent need to screen antibiotic-resistant GNB among HCWs and improve HCWs’ hand hygiene compliance to reduce the transmission of antibiotic-resistant GNB in the hospital.
Phu Huong Lan, Nguyen,Le Thi Phuong, Tu,Nguyen Huu, Hien,Thuy, Le,Mather, Alison E.,Park, Se Eun,Marks, Florian,Thwaites, Guy E.,Van Vinh Chau, Nguyen,Thompson, Corinne N.,Baker, Stephen Public Library of Science 2016 PLoS neglected tropical diseases Vol.10 No.8
<▼1><P>Invasive non-typhoidal <I>Salmonella</I> (iNTS) infections are now a well-described cause of morbidity and mortality in children and HIV-infected adults in sub-Saharan Africa. In contrast, the epidemiology and clinical manifestations of iNTS disease in Asia are not well documented. We retrospectively identified >100 cases of iNTS infections in an infectious disease hospital in Southern Vietnam between 2008 and 2013. Clinical records were accessed to evaluate demographic and clinical factors associated with iNTS infection and to identify risk factors associated with death. Multi-locus sequence typing and antimicrobial susceptibility testing was performed on all organisms. Of 102 iNTS patients, 71% were HIV-infected, >90% were adults, 71% were male and 33% reported intravenous drug use. Twenty-six/92 (28%) patients with a known outcome died; HIV infection was significantly associated with death (<I>p</I> = 0.039). <I>S</I>. Enteritidis (Sequence Types (ST)11) (48%, 43/89) and <I>S</I>. Typhimurium (ST19, 34 and 1544) (26%, 23/89) were the most commonly identified serovars; <I>S</I>. Typhimurium was significantly more common in HIV-infected individuals (<I>p</I> = 0.003). Isolates from HIV-infected patients were more likely to exhibit reduced susceptibility against trimethoprim-sulfamethoxazole than HIV-negative patients (<I>p</I> = 0.037). We conclude that iNTS disease is a severe infection in Vietnam with a high mortality rate. As in sub-Saharan Africa, HIV infection was a risk factor for death, with the majority of the burden in this population found in HIV-infected adult men.</P></▼1><▼2><P><B>Author Summary</B></P><P>Invasive non-typhoidal <I>Salmonella</I> (iNTS) infections occur when <I>Salmonella</I> bacteria, which normally cause diarrhea, enter the bloodstream and spread through the body. Invasive NTS infections have become a common cause of infection and death in children with malaria and adults with HIV in sub-Saharan Africa. However, it is unknown whether iNTS is as common or as severe outside sub-Saharan Africa. We evaluated over 100 iNTS cases from an infectious disease hospital in southern Vietnam admitted between 2008–2013. We used hospital records to determine the clinical features of iNTS disease and to identify risk factors associated with death and performed typing of the isolated organisms. The majority of patients were HIV positive (72/102, 71%), >90% of patients were adults, 71% were male and 33% reported intravenous drug use. The mortality rate of iNTS patients was 28% (26/92), and HIV infection was a significant risk factor for fatal outcome (<I>p</I> = 0.039). The serovars most commonly identified were <I>S</I>. Enteritidis and <I>S</I>. Typhimurium; <I>S</I>. Typhimurium was found more frequently in HIV-positive individuals (<I>p</I> = 0.003). We report that iNTS disease is a severe infection in Vietnam with a high mortality rate. Similar to sub-Saharan Africa, HIV infection was a strong risk factor for death.</P></▼2>