Time-dependent diffusion coefficient and conventional diffusion constant are calculated and analyzed to study diffusion of nanoparticles in polymer melts. A generalized Langevin equa- tion is adopted to describe the d...Time-dependent diffusion coefficient and conventional diffusion constant are calculated and analyzed to study diffusion of nanoparticles in polymer melts. A generalized Langevin equa- tion is adopted to describe the diffusion dynamics. Mode-coupling theory is employed to calculate the memory kernel of friction. For simplicity, only microscopic terms arising from binary collision and coupling to the solvent density fluctuation are included in the formalism. The equilibrium structural information functions of the polymer nanocomposites required by mode-coupling theory are calculated on the basis of polymer reference interaction site model with Percus-Yevick closure. The effect of nanoparticle size and that of the polymer size are clarified explicitly. The structural functions, the friction kernel, as well as the diffusion coefficient show a rich variety with varying nanoparticle radius and polymer chain length. We find that for small nanoparticles or short chain polymers, the characteristic short time non-Markov diffusion dynamics becomes more prominent, and the diffusion coefficient takes longer time to approach asymptotically the conventional diffusion constant. This constant due to the microscopic contributions will decrease with the increase of nanoparticle size, while increase with polymer size. Furthermore, our result of diffusion constant from mode- coupling theory is compared with the value predicted from the Stokes-Einstein relation. It shows that the microscopic contributions to the diffusion constant are dominant for small nanoparticles or long chain polymers. Inversely, when nanonparticle is big, or polymer chain is short, the hydrodynamic contribution might play a significant role.展开更多
Objective To evaluate the clinical characteristics and prognostic predictors of patients with diffuse alveolar hemorrhage(DAH)and/or interstitial lung disease(ILD)secondary to microscopic polyangiitis(MPA)in a Chinese...Objective To evaluate the clinical characteristics and prognostic predictors of patients with diffuse alveolar hemorrhage(DAH)and/or interstitial lung disease(ILD)secondary to microscopic polyangiitis(MPA)in a Chinese general hospital.Methods We retrospectively reviewed the medical records of MPA patients admitted to internal medicine departments between the year 2002 and 2012.The patients were divided into the ILD,DAH,DAH combined with ILD(DAHILD),and no pulmonary involvement(NPI)groups according to pulmonary involvement patterns.The clinical characteristics at diagnosis were analyzed.The risk factors associated with short-term death and long-term death were identified with Logistic regression and Cox analysis.Results Of 193 newly diagnosed MPA patients,181 patients were enrolled in the research,of which 19 had DAH alone,96 had ILD alone,18 had DAH and DAH concurrently,and 48 had NPI.The median of serum creatine level in the DAH group was 449μmol/L,significantly higher than that in the ILD group(123μmol/L,Nemenyi=-35.215,P=0.045)and DAHILD group(359μmol/L,Nemenyi=-43.609,P=0.007).The median follow-up time was 67(range:1-199)months.Patients in the ILD group were older than those in the DAH group(median:69 years vs.57 years,Nemenyi=43.853,P=0.005).The patients with both DAH and ILD had combined features of the two subtypes,and the highest mortality(72.2%at the end of follow-up).The elevated white blood cell count was a risk factor for short-term death(OR=1.103,95%CI:1.008-1.207,P=0.032 for one month;OR=1.103,95%CI:1.026-1.186,P=0.008 for one year).Old age(HR=1.044,95%CI:1.023-1.066,P<0.001),cardiovascular system involvement(HR=2.093,95%CI:1.195-3.665,P=0.010),poor renal function(HR=1.001,95%CI:1.000-1.002,P=0.032)were risk factors for long-term death.Pulmonary infections(38/54)were the leading causes of death,especially for the patients with ILD.Besides,49 patients suffered from pulmonary infections in the first year after diagnosis.Conclusions MPA patients who presented with different pulmonary involvement patterns have completely different clinical features.These subtypes probably have different pathogenesis and should be studied separately.展开更多
The aim of this theoretical investigation is the description of the multicomponent mass transfer process in the Nano- Composites (NC)—novel materials with the bi-functional matrix. The new theoretical NC Model is ass...The aim of this theoretical investigation is the description of the multicomponent mass transfer process in the Nano- Composites (NC)—novel materials with the bi-functional matrix. The new theoretical NC Model is assigned for the modern theoretical investigations of the multicomponent mass transfer kinetics in the bi-functional NC materials. This NC Model for the multicomponent mass transfer in the bi-functional NC matrix includes into the consideration the proposed key conception—two co-existing routes: I—chemical reactions onto the active NC centers-sites, and II—diffusion mass transfer inside the bi-functional NC matrix. All the results are presented in the terms of the additional key concept: propagating multicomponent concentration waves (W+) in the NC matrix. The used W+ concept for the description of the multicomponent NC mass transfer kinetics give the clear interpretation of the computerized results. The mass transfer process in the NC matrix has been described theoretically by computerized simulation. The results of the calculations are new and illustrated by author’s animations showing visually the propagation of the multicomponent concentration waves (W) inside the various NC matrixes: r-beads, cylindrical ro-fibers, or planar L-membranes. Two variants of modeling for mass transfer diffusion kinetics in the bi-functional NC matrixes with one (Variant 1), or two (Variant 2) dissociation-association reactions at the active nano-sites (R0) are considered theoretically.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.21173152）, the Ministry of Education of China （No.NCET-11-0359 and No.2011SCU04B31）, and the Science and Technology Department of Sichuan Province （No.2011HH0005）.
文摘Time-dependent diffusion coefficient and conventional diffusion constant are calculated and analyzed to study diffusion of nanoparticles in polymer melts. A generalized Langevin equa- tion is adopted to describe the diffusion dynamics. Mode-coupling theory is employed to calculate the memory kernel of friction. For simplicity, only microscopic terms arising from binary collision and coupling to the solvent density fluctuation are included in the formalism. The equilibrium structural information functions of the polymer nanocomposites required by mode-coupling theory are calculated on the basis of polymer reference interaction site model with Percus-Yevick closure. The effect of nanoparticle size and that of the polymer size are clarified explicitly. The structural functions, the friction kernel, as well as the diffusion coefficient show a rich variety with varying nanoparticle radius and polymer chain length. We find that for small nanoparticles or short chain polymers, the characteristic short time non-Markov diffusion dynamics becomes more prominent, and the diffusion coefficient takes longer time to approach asymptotically the conventional diffusion constant. This constant due to the microscopic contributions will decrease with the increase of nanoparticle size, while increase with polymer size. Furthermore, our result of diffusion constant from mode- coupling theory is compared with the value predicted from the Stokes-Einstein relation. It shows that the microscopic contributions to the diffusion constant are dominant for small nanoparticles or long chain polymers. Inversely, when nanonparticle is big, or polymer chain is short, the hydrodynamic contribution might play a significant role.
文摘Objective To evaluate the clinical characteristics and prognostic predictors of patients with diffuse alveolar hemorrhage(DAH)and/or interstitial lung disease(ILD)secondary to microscopic polyangiitis(MPA)in a Chinese general hospital.Methods We retrospectively reviewed the medical records of MPA patients admitted to internal medicine departments between the year 2002 and 2012.The patients were divided into the ILD,DAH,DAH combined with ILD(DAHILD),and no pulmonary involvement(NPI)groups according to pulmonary involvement patterns.The clinical characteristics at diagnosis were analyzed.The risk factors associated with short-term death and long-term death were identified with Logistic regression and Cox analysis.Results Of 193 newly diagnosed MPA patients,181 patients were enrolled in the research,of which 19 had DAH alone,96 had ILD alone,18 had DAH and DAH concurrently,and 48 had NPI.The median of serum creatine level in the DAH group was 449μmol/L,significantly higher than that in the ILD group(123μmol/L,Nemenyi=-35.215,P=0.045)and DAHILD group(359μmol/L,Nemenyi=-43.609,P=0.007).The median follow-up time was 67(range:1-199)months.Patients in the ILD group were older than those in the DAH group(median:69 years vs.57 years,Nemenyi=43.853,P=0.005).The patients with both DAH and ILD had combined features of the two subtypes,and the highest mortality(72.2%at the end of follow-up).The elevated white blood cell count was a risk factor for short-term death(OR=1.103,95%CI:1.008-1.207,P=0.032 for one month;OR=1.103,95%CI:1.026-1.186,P=0.008 for one year).Old age(HR=1.044,95%CI:1.023-1.066,P<0.001),cardiovascular system involvement(HR=2.093,95%CI:1.195-3.665,P=0.010),poor renal function(HR=1.001,95%CI:1.000-1.002,P=0.032)were risk factors for long-term death.Pulmonary infections(38/54)were the leading causes of death,especially for the patients with ILD.Besides,49 patients suffered from pulmonary infections in the first year after diagnosis.Conclusions MPA patients who presented with different pulmonary involvement patterns have completely different clinical features.These subtypes probably have different pathogenesis and should be studied separately.
文摘The aim of this theoretical investigation is the description of the multicomponent mass transfer process in the Nano- Composites (NC)—novel materials with the bi-functional matrix. The new theoretical NC Model is assigned for the modern theoretical investigations of the multicomponent mass transfer kinetics in the bi-functional NC materials. This NC Model for the multicomponent mass transfer in the bi-functional NC matrix includes into the consideration the proposed key conception—two co-existing routes: I—chemical reactions onto the active NC centers-sites, and II—diffusion mass transfer inside the bi-functional NC matrix. All the results are presented in the terms of the additional key concept: propagating multicomponent concentration waves (W+) in the NC matrix. The used W+ concept for the description of the multicomponent NC mass transfer kinetics give the clear interpretation of the computerized results. The mass transfer process in the NC matrix has been described theoretically by computerized simulation. The results of the calculations are new and illustrated by author’s animations showing visually the propagation of the multicomponent concentration waves (W) inside the various NC matrixes: r-beads, cylindrical ro-fibers, or planar L-membranes. Two variants of modeling for mass transfer diffusion kinetics in the bi-functional NC matrixes with one (Variant 1), or two (Variant 2) dissociation-association reactions at the active nano-sites (R0) are considered theoretically.
基金Project(2019YFC1803601)supported by the National Key Research and Development Program of ChinaProject(GCC[2023]038)supported by Guizhou“Hundred”High-level Innovative Talent Project,China。
