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Study on the synthesis of spin labeled poly(styrene-co-maleic acid)s and their segmental motion 被引量:1
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作者 Kaleem-Ur-Rahman Naveed Li Wang +9 位作者 Haojie Yu Qian Zhang Wei Xiong Raja Summe Ullah Ahsan Nazir Muhammad Usman Shah Fahad amin khan Md Alim Uddin Di Shen 《Magnetic Resonance Letters》 2022年第2期80-90,I0002,共12页
Study of the segmental mobility of polymer chains is important when the polymer is used as drag reduction agents of crude oil.Electron spin resonance(ESR)spectroscopy can provide important information about segmental ... Study of the segmental mobility of polymer chains is important when the polymer is used as drag reduction agents of crude oil.Electron spin resonance(ESR)spectroscopy can provide important information about segmental dynamics of polymer chains,which is related to their microenvironment.In this article,we employed an amphiphilic polymer to study the effect of hydrophilic/hydrophobic balance of the polymers on the segmental motion of polymer chains.Poly(styrene-co-maleic acid)(PSMA)was spin labeled with 4-amino TEMPO radicals by increasing the concentration of radical moiety on the polymer chains.The PSMA and spin labeled-PSMAs(SL-PSMAs)were characterized by nuclear magnetic resonance(NMR),Fourier transform infrared(FT-IR)spectroscopy,Cyclic voltammetry(CV)and ESR techniques.Inter-polymer complexes(IPCs)of SL-PSMA-2 were prepared by employing polyethylene glycols(PEGs)of varying molecular weights.The results showed that the increased hydrophobic interactions of nitroxide radicals on the SLPSMAs’chains reduced the rotational mobility of spin labels and the random coil-toglobular transition of polymer chains occurred at higher pH value for SL-PSMAs,which showed a slow motion component in the ESR spectra of SL-PSMAs.Further,by increasing the molecular weight of PEGs in IPCs the complexation was increased,which also reduced the rotational motion of spin labels due to interpolymer hydrogen bonding causing a slow motion component in the ESR spectra.©2021 The Authors. 展开更多
关键词 Electron spin resonance(ESR) Spin labeling Nitroxide radicals poly(styrene-co-maleic acid)s Segmental motion
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Modeling the dynamical behavior of the interaction of T-cells and human immunodeficiency virus with saturated incidence
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作者 Salah Boulaaras Rashid Jan +3 位作者 amin khan Ali Allahem Imtiaz Ahmad Salma Bahramand 《Communications in Theoretical Physics》 SCIE CAS CSCD 2024年第3期1-14,共14页
In the last forty years,the rise of HIV has undoubtedly become a major concern in the field of public health,imposing significant economic burdens on affected regions.Consequently,it becomes imperative to undertake co... In the last forty years,the rise of HIV has undoubtedly become a major concern in the field of public health,imposing significant economic burdens on affected regions.Consequently,it becomes imperative to undertake comprehensive investigations into the mechanisms governing the dissemination of HIV within the human body.In this work,we have devised a mathematical model that elucidates the intricate interplay between CD4^(+)T-cells and viruses of HIV,employing the principles of fractional calculus.The production rate of CD4^(+)T-cells,like other immune cells depends on certain factors such as age,health status,and the presence of infections or diseases.Therefore,we incorporate a variable source term in the dynamics of HIV infection with a saturated incidence rate to enhance the precision of our findings.We introduce the fundamental concepts of fractional operators as a means of scrutinizing the proposed HIV model.To facilitate a deeper understanding of our system,we present an iterative scheme that elucidates the trajectories of the solution pathways of the system.We show the time series analysis of our model through numerical findings to conceptualize and understand the key factors of the system.In addition to this,we present the phase portrait and the oscillatory behavior of the system with the variation of different input parameters.This information can be utilized to predict the long-term behavior of the system,including whether it will converge to a steady state or exhibit periodic or chaotic oscillations. 展开更多
关键词 HIV infection fractional-calculus dynamics of HIV iterative scheme dynamical behaviour mathematical model fractional derivatives
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