检索结果-南通市图书馆

How crystal configuration affects the position detection accuracy in pixelated molecular SPECT imaging systems?

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2017年第4期28卷 24-30页

作者： Hojjat Mahani Gholamreza Raisali Alireza Kamali-asl Mohammad Reza Ay Radiation Application Research School Nuclear Science and Technology Research Institute Tehran Iran Research Center for Molecular and Cellular Imaging Tehran University of Medical Science Tehran Iran Radiation Medicine Department Shahid Beheshti UniversityTehran Iran Department of Medical Physics and Biomedical Engineering Tehran University of Medical Science Tehran Iran

It is well known that inter-crystal scattering and penetration(ICS-P) are major spatial resolution limiting parameters in dedicated SPECT scanners with pixelated *** this study,the effect of ICS-P on crystal identification in different crystal configurations was evaluated using GATE Monte Carlo simulation.A ^(99m)Tc pencil-beam toward central crystal element was *** incident angle was assumed to vary from 0° to 45° in 5° *** effects of various crystal configurations such as pixel-size,pixel-gap,and crystal material were *** influence of photon energy on the crystal identification(CI) was also *** detection accuracy(PDA) was defined as a factor indicating performance of the ***,a set of ^(99m)Tc point-source simulations was performed in order to calculate peak-to-valley(PVR) ratio for each *** results show that the CsI(Na)manifests higher PDA than NaI(TI) and YAP(Ce).In addition,as the incident angle increases,the crystal becomes less accurate in positioning of the *** a crystal-dependent critical angle,the PDA monotonically *** PDA reaches 0.44 for the CsI(Na) at 45° beam *** PDAs obtained by the point-source evaluation also behave the same as for the pencil-beam *** addition,the PVRs derived from flood images linearly correlate their corresponding *** conclusion,quantitative assessment of ICS-P is mandatory for scanner design and modeling the system matrix during iterative reconstruction algorithms for the purpose of resolution modeling in ultra-high-resolution SPECT.

关键词： Monte Carlo GATE Molecular SPECT Position detection accuracy Pixelated crystal

QUANTITATIVE EVALUATION OF ARRANGEMENT OF MONOMERS IN LINEAR BINARY COPOLYMERS USING A MONTE CARLO SIMULATION METHOD

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2009年第2期27卷 195-208页

作者： Mohammad Najafi Mehdi Salami-Kalajahi Vahid Haddadi-asl Polymer Engineering Department Amirkabir University of TechnologyP.O.Box 15875-4413TehranIran National Petrochemical Company Petrochemical Research and Technology Company14358TehranIran

A Monte Carlo method was used to take thorough account of the influences of different reactivity ratios and initial feed compositions on copolymer *** model proves the lack of azeotropic behavior in systems in which r_A>1 and r_B<1 or vice versa;it is also able to calculate the drift in the copolymer properties:copolymer composition,and randomness ***,for each reactivity ratio pair given,there is a unique reaction conversion,at which macromolecules produced inherit their ...

关键词： Radical copolymerization Copolymer microstructure Copolymer composition Monte Carlo simulation Randomness parameter Copolymer heterogeneity Azeotrope point.

KINETIC MODELING OF ESTERIFICATION OF EPOXY RESIN IN THE PRESENCE OF TRIPHENYLPHOSPHINE FOR PRODUCING VINYL ESTER RESIN: MECHANISTIC RATE EQUATION

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2006年第6期24卷 599-608页

作者： M. Rafizadeh H. Ghasemi V. Haddadi-asl Polymer Engineering Department Amirkabir University of TechnologyP. O. Box 15785-4414TehranIran

Due to its mechanical properties and ease of use, vinyl ester resin is enjoying increasing consideration. This resin normally is produced by reaction between epoxy resin and unsaturated carboxylic acid. In the present study, bis-phenol A based epoxy resin and methacrylic acid was used to produce vinyl ester resin. The reaction was conducted under both stoichiometric and non-stoichiometric conditions in the presence of triphenylphosphine as catalyst. The stoichiometric and non-stoichiometric experiments were conducted at 95, 100, 105 and 110℃ and at 90 and 95℃, respectively. The first order rate equation and mechanism based rate equation were examined. Parameters are evaluated by least square method. A comparison of mechanism based rate equation and experimental data show an excellent agreement. Finally, Arrhenius equation and activation energy were presented.

关键词： Esterification Epoxy resin Vinyl ester resin Kinetic Rate equation.

A COMPREHENSIVE MONTE CARLO SIMULATION OF STYRENE ATOM TRANSFER RADICAL POLYMERIZATION

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2010年第4期28卷 483-497页

作者： Mohammad Najafi Hossein Roghani-Mamaqani Mehdi Salami-Kalajahi Vahid Haddadi-asl International Affairs Research Institute of Petroleum Industry(RIPI)***TehranIran Polymer Engineering Department Amirkabir University of TechnologyP.O.Box 15875-4413TehranIran

An optimized and high-performance Monte Carlo simulation is developed to take thorough account of four different cases of termination in styrene ATRP. According to the simulation results, the bimolecular termination rate constant sharply drops throughout the polymerization when either chain-length dependency of termination rate constant, gel effect, or both together is applied to the simulation. In addition, as expected, the initiator is quickly decomposed at the early stages of the polymerization. The concentration of the catalyst in lower oxidation state decreases at first and then plateaus at higher conversion; furthermore, the steady concentration of Ml^nY/L in the polymerization is the highest when the chain-lengthdependent diffusion-controlled termination rate constant is employed in the simulation. The rates of deactivation and chain end degradation reactions are also smaller in this case. Therefore, the fraction of dormant chains is higher throughout the reaction and consequently the portion of dead polymers decreases. Besides, molecular weight increases linearly with conversion; however, when neither gel effect nor chain-length dependency of termination rate constant is considered, the molecular weight deviates from linearity at the end of the reaction. The peak of chain length distribution shifts toward higher molecular weight too during the reaction. Finally, the molecular weight distribution broadens at higher conversion; however, the chain length distribution of polymers produced under conditions of applying chain-length-dependent diffusion-controlled termination rate constant is narrower.

关键词： Styrene ATRP Monte Carlo simulation Chain length distribution Gel effect Chain-length-dependent termination.

Cataract in diabetes mellitus

在线全文

学校读者我要写书评

暂无评论

World Journal of Diabetes 2019年第3期10卷 140-153页

作者： Hasan Kiziltoprak Kemal Tekin Merve Inanc Yasin Sakir goker Department of Ophthalmology University of Health Sciences Ulucanlar Eye Training and Research Hospital Ankara 06240 Turkey Ophthalmology Department Ercis State Hospital Van 65400 Ercis Turkey

Diabetes mellitus (DM) is a chronic systemic disease that has increases in prevalence over time. DM can affect all ocular structures, with cataract being the most common ocular complication. Cataract is the leading cause of blindness worldwide. Due to several mechanisms, there is an increased incidence of cataract formation in the diabetic population. Advancements in technology have now made cataract surgery a common and safe procedure. However, the diabetic population is still at risk of vision-threatening complications, such as diabetic macular edema (ME), postoperative ME, diabetic retinopathy progression, and posterior capsular opacification.

关键词： Diabetes Cataract Complications Surgery

A new method for estimating the longevity and degradation of hotovoltaic systems considering weather states

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

Frontiers in Energy 2016年第3期10卷 277-285页

作者： Amir AHADI Hosein HAYATI Joydeep MITRA Reza ABBASI-asl Kehinde AWODELE Young Researchers and Elite Club Ardabil Branch Islamic Azad University Ardabil *** Iran Department of Electrical and Computer Engineering Michigan State University East Lansing MI 48823 USA Department of Electrical Engineering and Computer Sciences University of California Berkeley CA 94720 USA Department of Electrical Engineering University of Cape Town Cape Town 7701 South Africa

The power output of solar photovoltaic （PV） systems is affected by solar radiation and ambient temperature. The commonly used evaluation techniques usually overlook the four weather states which are clear, cloudy, foggy, and rainy. In this paper, an ovel analytical model of the four weather conditions based on the Markov chain is proposed. The Markov method is well suited to estimate the reliability and availability of systems based on a continuous stochastic process. The proposed method is generic enough to be applied to reliability evaluation of PV systems and even other applications. Further aspects investigated include the new degradation model for reliability predication of PV modules. The results indicate that the PV module degradation over years, failures, and solar radiation must be considered in choosing an efficient PV system with an optimal design to achieve the maximum benefit of the PV system. For each aspect, a method is proposed, and the complete focusing methodology is expounded and validated using simulated point targets. The results also demonstrate the feasibility and applic- ability of the proposed method for effective modeling of the chronological aspects and stochastic characteristics of solar cells as well as the optimal configuration and sizing of large PV plants in terms of cost and reliability.

关键词： photovoltaic (PV) systems solar cell Markov model weather effects

Celestine blue as a new indicator in electrochemical DNA biosensors

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2016年第1期59卷 128-134页

作者： Ezat Hamidi-asl Jahan Bakhsh Raoof Abdolraoof Samadi Meibodi Zahra Haghnavaz Bazgir Eletroanalytical Chemistry Research Laboratory Department of Analytical Chemistry Faculty of Chemistry University of MazandaranBabolsarIran Spectroscopic Research Laboratory Department of Analytical ChemistryFaculty of Chemistry University of MazandaranBabolsarIran

Celestine blue(CB)was introduced as a new electroactive indicator in DNA *** interaction of CB with DNA was investigated by electrochemical and spectroscopic *** effect of buffer kind and p H on the electrochemical behavior of CB was *** peak currents of CB were linearly related to DNA concentration in the range of 5.0×10^(-9) to 1.0×10^(-7)mol/*** detection limit of this approach was 4.76×10^(-10) mol/*** on spectrometry data a hypochromic effect was observed in UV-Vis spectra of CB with increasing DNA *** results illustrate the possible interaction mode between CB and DNA is electrostatic binding.

关键词： celestine blue differential pulse voltammetry DNA biosensor electroactive indicator

Developing a Nano-Biosensor for DNA Hybridization Using a New Electroactive Label

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2011年第11期29卷 2541-2551页

作者： Raoof, Jahan Bakhsh Ojani, Reza Ebrahimi, Maryam Hamidi-asl, Ezat Electroanalytical Chemistry Research Laboratory Department of Analytical Chemistry Faculty of Chemistry University of Mazandran Babolsar Iran

Development of electrochemical DNA hybridization biosensors based on carbon paste electrode （CPE） and gold nanoparticle modified carbon paste electrode （NGMCPE） as transducers and ethyl green （EG） as a new electroac- tive label is described. Electrochemical impedance spectroscopy and cyclic voltammetry techniques were applied for the investigation and comparison of bare CPE and NGMCPE surfaces. Our voltammetric and spectroscopic studies showed gold nanoparticles are enable to facilitate electron transfer between the accumulated label on DNA probe modified electrode and electrode surface and enhance the electrical signals and lead to an improved detection limit. The immobilization of a 15-mer single strand oligonucleotide probe on the working electrodes and hybridiza- tion event between the probe and its complementary sequence as a target were investigated by differential pulse voltammetry （DPV） responses of the EG accumulated on the electrodes. The effects of some experimental variables on the performance of the biosensors were investigated and optimum conditions were suggested. The selectivity of the biosensors was studied using some non-complementary oligonucleotides. Finally the detection limits were calculated as 1.35×10^-10 mol/L and 5.16×10^-11 mol/L on the CPE and NEGCPE, respectively. In addition, the bio-sensors exhibited a good selectivity, reproducibility and stability for the determination of DNA sequences.

关键词： ethyl green hybridization detection DNA recognition gold nanoparticle modified carbon paste elec- trode biosensors nucleotides

Efficacy of topical chamomile on the incidence of phlebitis due to an amiodarone infusion in coronary care patients:a double-blind,randomized controlled trial

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

Journal of Integrative Medicine 2017年第5期15卷 373-378页

作者： Maryam Sharifi-Ardani Leili Yekefallah Saeed Asefzadeh Marjan Nassiri-asl School of Nursing and Midwifery Qazvin University of Medical SciencesQazvin 341197-5981Iran Social Determinants of Health Research Center Qazvin University of Medical SciencesQazvin 341197-5981Iran Cellular and Molecular Research Center Department of PharmacologyQazvin University of Medical SciencesQazvin 341197-5981Iran

BACKGROUND：Amiodarone is a useful antiarrhythmic ***,caused by intravenous amiodarone,is common in patients in coronary care units（CCUs）.OBJECTIVE：The aim of this study was to evaluate the effect of topical chamomile on the incidence of phlebitis due to the administration of an amiodarone infusion into the peripheral ***,SETTING,PARTICIPANTS AND INTERVENTIONS：This was a randomized,double-blind clinical trial,conducted on 40 patients（n=20 per group）in two groups—an intervention group（chamomile ointment）and a control group（lanoline,as a placebo）,hospitalized in the CCUs and undergoing an amiodarone infusion into the peripheral vein over 24 *** the cannulation and commencement of the infusion,placebo or chamomile ointment was rubbed in,up to 10 cm superior to the catheter and repeated every eight hours for three *** cannula site was then assessed based on the phlebitis *** OUTCOME MEASURES：The incidence and time of occurrence of phlebitis,relative risk,severity of phlebitis were the main outcome ***：Nineteen patients（19/20）in the control group had phlebitis on the first day of the study and one patient（20/20）on the second *** the intervention group,phlebitis occurred in 13 cases（13/20）on the first day and another two（2/7）was found on the second *** incidence of phlebitis was significantly different between two groups（P=0.023）.The cumulative incidence of phlebitis in the intervention group（15/20）is significantly later and lower than that in the control group（20/20）during two days（P=0.008）.Two patients in the intervention group did not develop phlebitis at all during the 3-day ***,the relative risk of phlebitis in the two groups was 0.68（P=0.008 5）.A significant difference was not observed with regard to phlebitis severity in both ***：It seems that phlebitis occurred to a lesser extent and at a later time frame in the intervention group compared to control *** chamomile may be e

关键词： phlebitis amiodarone prevention chamomile clinical trial plants, medicinal