检索结果-南通市图书馆

Quantification of the impact of TOF and PSF on PET images using the noise-matching concept: clinical and phantom study

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2017年第11期28卷 258-265页

作者： M. Shekari P. Ghafarian S. Ahangari M. r. Ay Department of Medical Physics and Biomedical Engineering Tehran University of Medical Sciences Tehran Iran research Center for Molecular and Cellular Imaging Tehran University of Medical Sciences Tehran Iran Chronic respiratory Diseases research Center National Research Institute of Tuberculosis and Lung Diseases(NRITLD) Shahid Beheshti University of Medical SciencesTehran Iran PET/CT and Cyclotron Center Masih Daneshvari HospitalShahid Beheshti University of Medical Sciences Tehran Iran

This study was to assess quantitatively the accuracy of ^(18)F-FDG PET/CT images reconstructed by TOF+PSF and TOF only, considering the noise-matching concept to minimize probable bias in evaluating algorithm performance caused by noise. PET images of similar noise level were considered. Measurements were made on an inhouse phantom with hot inserts of Φ10–37 mm, and oncological images of 14 patients were analyzed. The PET images were reconstructed using the OSEM, OSEM+TOF and OSEM+TOF+PSF algorithms. Optimal reconstruction parameters including iteration, subset, and FWHM of post-smoothing filter were chosen for both the phantom and patient data. In terms of quantitative accuracy, the recovery coefficient(rC) was calculated for the phantom PET images. The signal-to-noise ratio(SNr),lesion-to-background ratio(LBr), and SUV_(max)were evaluated from the phantom and clinical data. The smallest hot insert(Ф10 mm) with 2:1 activity concentration ratio could be detected in the PET image reconstructed using the TOF and TOF+PSF algorithms, but not the OSEM algorithm. The relative difference for SNr between the TOF+PSF and OSEM showed significantly higher values for smaller sizes, while SNr change was smaller for Ф22–37 mm inserts both 2:1 and 4:1 activity concentration ratio. In the clinical study, SNr gains were 1.6 ± 0.53 and 2.7 ± 0.74 for the TOF and TOF+PSF, while the relative difference of contrast was 17 ± 1.05 and 41.5 ± 1.85% for the TOF only and TOF+PSF, respectively. The impact of TOF+PSF is more significant than that of TOF reconstruction, in smaller inserts with low activity concentration ratio. In the clinical PET/CT images, the use of the TOF+PSF algorithm resulted in better SNr and contrast for lesions, and the highest SUV_(max)was also seen for images reconstructed with the TOF+PSF algorithm.

关键词： Time of flight (TOF) Point spread function(PSF) Lesion detectability PET Quantification Image reconstruction SUV

Nash Inequalities for General Symmetric Forms

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 1999年第3期15卷 353-370页

作者： Mufa Chen Department of Mathematics, Beijing Normal University, Beijing 100875, P. r. China Department of Mathematics Beijing Normal University Beijing P. R. China

This paper deals with the Nash inequalities and the related ones for general symmetric forms which can be very much unbounded. Some sufficient conditions in terms of the isoperimetric inequalities and some necessary conditions for the inequalities are presented. The resulting conditions can be sharp qualitatively as illustrated by some examples. It turns out that for a probability measure, the Nash inequalities are much stronger than the Poincare and the logarithmic Sobolev inequalities in the present context.

关键词： Nash inequality Symmetric form Isoperimetric Inequality Jump process

Study of Transport Properties in Armchair Graphyne Nanoribbons: A Density Functional Approach

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2016年第7期65卷 143-148页

作者： S.Golafrooz Shahri M.r.roknabadi N.Shahtahmasebi M.Behdani Department of Physics Ferdowsi University of Mashhad

In present paper, the non-equilibrium Green function(NEGF) method along with the density functional theory(DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne(γ-graphyne) nanoribbons. The results show that all the studied nanoribbons are semiconductor and their band gaps decrease as the widths of nanoribbons increase, which will result in increasing current at a certain voltage. Also our results show the promising application of armchair graphyne nanoribbons in nano-electrical devices.

关键词： transport properties density functional theory graphyne nanoribbons non-equilibrium green function

Performance of an activated carbon made from waste palm shell in simultaneous adsorption of SO_x and NO_x of flue gas at low temperature

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第1期52卷 198-203页

作者： S. SUMATHI S. BHATIA K.T. LEE A. r. MOHAMED School of Chemical Engineering Engineering Campus Universiti Sains Malaysia 14300 Nibong Tebal Pulau Pinang

This study examined the individual and simultaneous adsorption of SO{in{itx}} (SO{in{it2}}) and NO{in{itx}} (NO-NO{in{it2}}) on activated carbon prepared from waste palm shell. The adsorption process was examined in a fixed bed reactor at low temperatures (100\2-300\dgC). For individual adsorption without any catalytic activation, SO{in{itx}} showed good adsorption whereas NO{in{itx}} was very much poor. In the simultaneous adsorption of SO{in{itx}} and NO{in{itx}}, SO{in{itx}} showed greater adsorption affinity than NO{itx}. For palm shell activated carbon (PSAC) impregnated with metal catalyst (Ni and Ce) the concentration adsorbed profile showed that the amount of SO{in{itx}} adsorbed decreased regularly, while the amount of the adsorbed NO{in{itx}} increased irregularly. The properties of the pure and impregnated PSAC were analyzed by BET, SEM and EDX. These investigations indicated that PSAC impregnated with metal catalyst is the determining factor in the adsorption of SO{in{itx}} and NO{in{itx}} simultaneously.

关键词： palm shell activated carbon flue gas SO_x NO_x

The Covalent Binding of Genistein to the Non-prosthetic-heme-moiety of Bovine Lactoperoxidase Leads to Enzymatic Inactivation

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2011年第3期24卷 284-290页

作者： Hebron C. CHANG Daniel r. DOErGE ChengHong HSIEH LIN YingJu FuuJen TSAI Department of Biotechnology Asia University Taichung 41354 Taiwan China Division of Biochemical Toxieology National Center for Toxicological research FDA Jeffkrson AR 72079 USA Department of Health and Nutritional Biotechnology Asia University Taichung 41354 Taiwan China Genetic Center China Medical University Taichung 40402 Taiwan China

Objective Genistein, a major soy isoflavone metabolite （SIF）, inactivates oxidation activity of bovine lactoperoxidase （LPO）. Modification of the heme moiety of LPO by nitrogen-containing compounds has been shown to inactivate LPO. In contrast, SIF mediated inactivation of LPO does not involve a heme modification and the mechanism of SIF inhibition is poorly understood. Methods After inactivation of LPO by genistein in the presence of H202, trypsin-digested LPO peptide fragments were collected and analyzed by MALDI-TOF-MS to characterize the chemical binding of genistein（s） to LPO. results The heme moiety of LPO was not modified by genistein. A covalent binding study showed that 3H-genistein bound to LPO with a ratio of ~12 to 1. After HPLC analysis and peak collection, trypsin-digested peptide fragments were analyzed by MALDI-TOF-MS. The 3H-genistein co-eluted peptide fragments （rT=24 min） were putatively identified as 1991VGYLDEEGVLDQNr214 with two bound genistein molecules or a genistein dimer （2 259 Da）, 486TPDNIDIWlGGNAEPMVEr504 with two bound genistein molecules or a genistein dimer （2 663 Da）, and 161ArWLPAEYEDGLALPFGWTQr182 with three bound genistein molecules or a genistein trimer （3 060 Da）. The fragment with a mass of 2 792 Da （rT=36 min） was identified as 132CDENSPYr139 with three genistein molecules or a genistein trimer. Conclusions The results suggest that LPO was inactivated by irreversible covalent binding of genistein or genistein polymers to particular peptide fragments constituting regions of the outward domain. No genistein interaction with the prosthetic heme moiety of LPO was observed.

关键词： Lactoperoxidase Genistein Modification of heme Covalent binding Peptide fragments

Microalgae wet extraction using N-ethyl butylamine for fatty acid production

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2016年第1期1卷 79-83页

作者： Ying Du Boelo Schuur Sascha r.A.Kersten Derk W.F.Brilman University of Twente Sustainable Process Technology Group(SPT)Faculty of Science and Technology

Microalgae are considered a promising feedstock for the production of food ingredients, cosmetics, pharmaceutical products and *** energy intensity of drying and cell breaking of algae and solvent recovery afterwards hindered the route of algae biorefinery. In this work the influences of freeze drying and cell breaking to the extraction efficiency of crude lipid yield and fatty acid yield were investigated. results showed that drying and cell breaking are not necessary for N-ethyl butylamine extraction, because good yields were obtained without. Crude lipid yield and fatty acid yield using N-ethyl butylamine were comparable with Bligh & Dyer extraction, making N-ethyl butylamine a candidate for further development of an energy efficient lipid extraction technology for non-broken microalgae.

关键词： Microalgae Lipids Extraction Switchable solvent Secondary amine

Nonadiabatic acceleration of plasma sheet ions related to ion cyclotron waves

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第12期57卷 2434-2440页

作者： WANG Zhi Qiang CAO Jin Bin rME Henri DANDOUrAS Iannis MA Yu Duan Department of Space Science and Application College of Astronautics Nanjing University of Aeronautics and Astronautics University of Toulouse UPS-OMP IRAP Toulouse 31082 France The French National Centre for Scientific research The Research Institute in Astrophysics and Planetology Space Science Institute School of Astronautics Beihang University

The nonadiabatic acceleration of plasma sheet ions is important to the understanding of substorm energetic injections and the formation of ring current. Previous studies show that nonadiabatic acceleration of protons by magnetic field dipolarization is hard to occur at X>–10 rE because the time-scale of dipolarization(several minutes) is much larger than the gyroperiod of protons there(several seconds). In this paper, we present a case of nonadiabatic acceleration of plasma sheet ions observed by Cluster on October 30, 2006 at(XGSM, YGSM)=(-7.7, 4.7) rE. The nonadiabatic acceleration of ions is caused not by previously reported magnetospheric dipolarization but by the ultra low frequency(ULF) waves during magnetospheric dipolarization. The nonadiabatic acceleration of ions generates a new energy flux structure of ions, which is characterized by the usual energy flux increase of ions(28–80 ke V) and a concurrent energy flux decrease of ions in a lower energy range(10 e V–20 ke V). These new observations constitute a complete physical picture: The lower energy ions absorb the wave energy, and thus get accelerated to higher energy. We use a nonadiabatic model to interpret the ion energy flux variations. Both analytic and simulation results are in good agreement with the observations. This indicates that the nonadiabatic acceleration associated with ULF waves superposed on dipolarized magnetic field is an effective mechanism for ion energization in the near-Earth plasma sheet. The presented energy flux structures can be used as a proxy to identify the similar dynamic process.

关键词： nonadiabatic acceleration ion cyclotron waves wave-particle interaction

Survey of robotics in Education, Taxonomy, Applications, and Platforms during COVID-19

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第4期67卷 687-707页

作者： Hussain A.Younis A.S.A.Mohamed r.Jamaludin M.N.Ab Wahab College of Education for Women University of Basrah BasrahIraq School of Computer Sciences Universiti Sains MalaysiaMinden11800PenangMalaysia Centre For Instructional Technology&Multimedia Universiti Sains MalaysiaMinden11800PenangMalaysia

The coronavirus disease 2019(COVID-19)is characterized as a disease caused by a novel coronavirus known as severe acute respiratory coronavirus syndrome 2(SArS-CoV-2;formerly known as 2019-nCoV).In December 2019,COVID-19 began to appear in a few *** the beginning of 2020,it had spread to most countries across the *** is when education challenges began to *** COVID-19 crisis led to the closure of thousands of schools and universities all over the *** a situation requires reliance on e-learning and robotics education for students to continue their studies to avoid the mingling between people and *** relation to this alternative learning solution,the present study was conducted.A systematic literature review on educational robotics(Er)keywords between 2015–2020 was carried out for the purpose to review a total of 2253 articles from the selected sources;Scopus(452),Taylor&Francis(311),Science Direct(427),IEEE Xplore(221),and Web of Science(842).This review procedure was labelled as Taxonomy *** ltering Taxonomy 1,it was found that 98 scientic articles formed the so-called Taxonomy II that was categorized into six categories:(i)robotics concepts,(ii)Device,(iii)robotic applications,(iv)Manufacturing robots,(v)robotics analysis,and(vi)Education/*** this study,only 35 articles in this specic eld were selected,of which were then assigned into three categories:(i)Application,(ii)Platform,and(iii)*** results show that the application category carries 17.4%,platform 20%,and education 22.85%.This study serves as the application platform to help students,academics,and researchers.

关键词： COVID-19 educational educational robotics taxonomy application platform

Clinical significance of connective tissue growth factor in hepatitis B virus-induced hepatic fibrosis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2012年第18期18卷 2280-2286页

作者： rong-Li Piao David r Brigstock Jie Zhu Man-Li Zhang run-Ping Gao Department of Hepatie-biliary-panereatie Medicine First Hospital Jilin University Changehun 130021 Jilin Province China Division of Pediatric Surgery Department of Surgery The Research Institute at Nationwide Children＇s Hospital The Ohio State University Columbus OH 43210 United States

AIM:To determine the utility of connective tissue growth factor(CCN2/CTGF) for assessing hepatic fibrosis in hepatitis B virus(HBV)-induced chronic liver diseases(CLD-B).METHODS:Enzyme-linked immunosorbent assay was used to measure CCN2 in sera from 107 patients with chronic hepatitis B(CHB) and 39 patients with HBVinduced active liver cirrhosis and 30 healthy *** samples from 31 patients with CHB,8 patients with HBV-induced liver cirrhosis and 8 HBV carriers with normal liver histology were examined for transforming growth factor β-1(TGF-β1) or CCN2 mrNA levels by in situ hybridization,and computer image analysis was performed to measure integrated optimal density(IOD) of CCN2 mrNA-positive cells in liver *** inflammation grading and fibrosis staging were evaluated by H and E staining and Van Gieson's ***:Serum CCN2 concentrations were,respectively,4.0-or 4.9-fold higher in patients with CHB or active liver cirrhosis as compared to healthy individuals(P re was good consistency between the levels of CCN2 in sera and CCN2 mrNA expression in liver tissues(r = 0.87,P ra were increased with the enhancement of histological fibrosis staging in patients with CLD-B(r = 0.85,P rum CCN2 was a reliable marker for the assessment of liver fibrosis,with areas under the receiver operating characteristic(rOC) curves(AUC) of 0.94 or 0.85 for,respectively,distinguishing normal liver controls from patients with F1 stage liver fibrosis or discriminating between mild and significant ***:Detection of serum CCN2 in patients with CLD-B may have clinical significance for assessment of severity of hepatic fibrosis.

关键词： Connective tissue growth factor Liver fibrosis Chronic hepatitis B Chronic liver disease Chronic hepatitis C