Luminescence kinetics of semiconductor doped glasses in the long time region

1992 ◽  
Vol 71 (2) ◽  
pp. 942-945 ◽  
Author(s):  
S. Burkitbaev ◽  
M. Bertolotti ◽  
E. Fazio ◽  
A. Ferrari ◽  
G. Liakhou ◽  
...  
Keyword(s):  
Luminescence Kinetics ◽  
Long Time ◽  
Doped Glasses ◽  
Time Region ◽  
Kinetics Of

Studies of the Hydrolysis and Polymerization of Silicon Alkoxides in Basic Alcohol Solutions

1988 ◽  
Vol 121 ◽  
Author(s):  
G. H. Bogush ◽  
G. L. Dickstein ◽  
P. Lee ◽  
K.C. ◽  
C. F. Zukoski
Keyword(s):  
Aqueous Ethanol ◽  
Average Particle Size ◽  
Reaction Medium ◽  
Particle Growth ◽  
Ionic Species ◽  
Average Particle ◽  
Silicon Alkoxides ◽  
Long Time ◽  
Time Region ◽  
Kinetics Of

ABSTRACTWe report here an experimental technqiue based on changes in reaction medium volume which we have used to observe the kinetics of hydolysis and polymerization of TEOS in aqueous ethanol solutions containing NH3. Our results show that there are three distinct reaction regions. By combining these results with determinations of change in reaction medium conductivity and average particle size, we are able to link the short and long time regions to TEOS hydrolysis and particle growth respectively. The intermediate reaction time region is not associated with hydrolysis, loss of ionic species due to condensation or to particle growth.

Long-time luminescence kinetics of localized excitons and conduction band edge smearing in ZnSe(1−c)Tec solid solutions

JETP Letters ◽  
2000 ◽  
Vol 72 (6) ◽  
pp. 320-323 ◽  
Author(s):  
A. Klochikhin ◽  
S. G. Ogloblin ◽  
S. Permogorov ◽  
A. Reznitsky ◽  
C. Klingshirn ◽  
...  
Keyword(s):  
Conduction Band ◽  
Solid Solutions ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Luminescence Kinetics ◽  
Long Time ◽  
Localized Excitons ◽  
Kinetics Of

scholarly journals Multifaceted phase ordering kinetics of an antiferromagnetic spin-1 condensate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joanna Pietraszewicz ◽  
Aleksandra Seweryn ◽  
Emilia Witkowska
Keyword(s):  
Scaling Laws ◽  
Study Phase ◽  
One Dimensional ◽  
Phase Domain ◽  
Ordering Kinetics ◽  
Domain Coarsening ◽  
Long Time ◽  
Phase Ordering ◽  
Kinetics Of ◽  
Antiferromagnetic Spin

AbstractWe study phase domain coarsening in the long time limit after a quench of magnetic field in a quasi one-dimensional spin-1 antiferromagnetic condensate. We observe that the growth of correlation length obeys scaling laws predicted by the two different models of phase ordering kinetics, namely the binary mixture and vector field. We derive regimes of clear realization for both of them. We demonstrate appearance of atypical scaling laws, which emerge in intermediate regions.

scholarly journals Neutralizing and binding antibody kinetics of COVID-19 patients during hospital and convalescent phases

2021 ◽  
Author(s):  
Xiang-Yang Yao ◽  
Wei Liu ◽  
Zhi-Yong Li ◽  
Hua-Long Xiong ◽  
Ying-Ying Su ◽  
...  
Keyword(s):  
Regression Coefficient ◽  
Control Strategies ◽  
Illness Onset ◽  
Relative Contribution ◽  
Long Time ◽  
Iga Antibody ◽  
Binding Antibody ◽  
Blood Specimens ◽  
Antibody Kinetics ◽  
Kinetics Of

Abstract Background: Knowledge of host immune response after natural SARS-CoV-2 infection is essential for the direction of vaccination and epidemiological control strategies against COVID-19.Methods: Thirty-four COVID-19 patients were enrolled with 244 serial blood specimens (38.1% after hospital discharge) collected to explore the chronological evolution of neutralizing (NAb), total (TAb), IgM, IgG and IgA antibody in parallel.Results: IgG titers reached a peak later (35 days postonset) than those of Nab, Ab, IgM and IgA (25 days postonset). IgM levels declined with an estimated half-life of 35 days postonset, which was more rapid than those of IgA and IgG (73-76 days postonset). All patients remained positive for NAb, IgG and IgA up to 3 months after illness onset. The relative contribution of IgM to NAb was higher than that of IgG (standardized β regression coefficient: 0.53 vs 0.48). However, the relative contribution of IgG to NAb increased and that of IgM further decreased after 6 weeks postonset.Conclusions: This study suggests that SARS-CoV-2 infection induces robust neutralizing and binding antibody responses in patients. Humoral immunity against SARS-CoV-2 acquired by infection may persist for a relatively long time.

scholarly journals Kinetics of the cercaria-schistosomul um transformation in vivo: 2. The effect of oxamniquine

1985 ◽  
Vol 18 (4) ◽  
pp. 251-255 ◽  
Author(s):  
A. L. Melo ◽  
L.H. Pereira
Keyword(s):  
Peritoneal Cavity ◽  
Abdominal Cavity ◽  
Long Time ◽  
Peritoneal Washings ◽  
High Doses ◽  
Kinetics Of

To study the cercaria-schistosomulum transformation in vivo, underthe influence of an antischistosomal compound (oxamniquine), a model using cercarial infections into the abdominal cavity of mice was chosen. This procedure provided easy and reproducible recoveries of larvae from peritoneal washings with appropriate solutions for a long time (30 to 180 min) after inoculation. The results show that high doses of oxamniquine (given intramuscularly one hour before the infection) produce a marked delay in the kinetics of the cercaria-schistosomulum transformation. Cercariae, tail-less cercarial bodies and schistosomula were recovered from the peritoneal cavity ofdrug treated mice in numbers significantly different from those recovered from untreated mice.

scholarly journals The effect of loading frequency on the cyclic mechanical behavior of polyethylene

2015 ◽  
Vol 18 (4) ◽  
pp. 162-169
Author(s):  
Thao Song Thanh Nguyen ◽  
Nhung Thi Tuyet Le
Keyword(s):  
Experimental Investigation ◽  
Mechanical Behavior ◽  
Hysteresis Loop ◽  
Room Temperature ◽  
Tensile Tests ◽  
Loading Frequency ◽  
Ratcheting Strain ◽  
Accumulated Strain ◽  
Long Time ◽  
Kinetics Of

An experimental investigation into ratcheting strain and stress-strain hysteresis loop in stress-controlled cyclic tensile tests at room temperature was performed to determine the effect of loading frequency on the cyclic mechanical behavior of highdensity polyethylene (HDPE). It was found that frequencies ranging from 0.01 Hz up to 1 Hz mostly affects the accumulated strain over related time scales (i.e that of the cycle itself) and not over long time scale (i.e. during the full test). In addition, the higher the frequency is, the more closed and vertical the loops are. Furthermore, the frequency affects only on the kinetics of stabilization of ratcheting strain but not on one of hysteresis loop.

Kinetics of homogeneous chemical reactions

2005 ◽  
Author(s):  
Boris S. Bokstein ◽  
Mikhail I. Mendelev ◽  
David J. Srolovitz
Keyword(s):  
Chemical Reactions ◽  
Irreversible Thermodynamics ◽  
Kinetic Process ◽  
Chemical Reaction Kinetics ◽  
Long Time ◽  
Homogeneous Chemical ◽  
Parallel Reactions ◽  
Diffusive Processes ◽  
Kinetics Of

Kinetics considers the rates of different processes. Chemical kinetics refers to the rates and mechanisms of chemical reactions and mass transfer (diffusion). Recall that since thermodynamic equilibrium implies that the rates of all processes are zero, time is not a thermodynamic variable. Rather, time is the new parameter introduced by the consideration of kinetic processes. The rate of a kinetic process and how it depends on time is determined, in part, by the degree of the deviation from equilibrium. If the deviation from equilibrium is small, the rate decreases (without changing sign) as the system approaches equilibrium. If the deviation from equilibrium is large, the situation is more complicated. For example, non-monotonic (including oscillatory) processes are possible. The sign of the rate can change during such processes; that is, the reaction can proceed in one direction and then the other. Additionally, if the deviation from equilibrium is large, small changes to the system can produce very large changes in the rate of the kinetic process (i.e. chaos). Non-equilibrium, yet nearly stationary states of the system can arise (i.e. states that exist for a very long time). Finally, if the deviation from equilibrium is very large, the system can explode (i.e. the process continues to accelerate with time). In this chapter, we develop a formal description of the kinetics of rather simple chemical reactions. Consecutive and parallel reactions will also be considered here. A more general approach (irreversible thermodynamics) will be considered in Chapter 9. In Chapter 10, we examine diffusive processes. Then, in Chapter 11, we consider the kinetics of heterogeneous processes. In order to start the study of chemical reaction kinetics, we must first define what we mean by the rate of reaction. Consider the following homogeneous reaction: . . . Cl2 + 2NO → 2NOCl. (8.1) . . .

Temperature Dependence of the Decay of Optically Excited Charge Carriers in Amorphous Silicon

2003 ◽  
Vol 762 ◽  
Author(s):  
J. Whitaker ◽  
P. C. Taylor
Keyword(s):  
Temperature Dependence ◽  
Amorphous Silicon ◽  
State Density ◽  
Charge Carriers ◽  
Band Tail ◽  
Spin Resonance ◽  
Recombination Processes ◽  
Long Time ◽  
Tail Structure ◽  
Kinetics Of

AbstractWe report the temperature dependence of the growth and decay of the optically induced electron spin resonance (LESR) on short and long time scales (10-3 s < t < 2500 s). This range of times spans the region between previously published photoluminescence and the LESR data. In addition, we examine the steady-state density of optically excited charge carriers as a function of temperature. These measurements lead to a better understanding of the band tail structure of amorphous silicon as well as the kinetics of the excitation and recombination processes.

Persistent photoconductivity in AlGaN films Grown by mocvd

1998 ◽  
Vol 512 ◽  
Author(s):  
A. Y. Polyakov ◽  
N. B. Smirnov ◽  
A. V. Govorkov ◽  
J. M. Redwing
Keyword(s):  
Activation Energy ◽  
Light Intensity ◽  
High Resistivity ◽  
Persistent Photoconductivity ◽  
Quasi Fermi Level ◽  
Decay Times ◽  
Long Time ◽  
Light Excitation ◽  
Si Doped ◽  
Kinetics Of

ABSTRACTPhotocurrent transients due to illumination by above-bandgap and subbandgap light were studied for Si doped and undoped films of AlGaN grown by MOCVD on sapphire and having compositions ranging from 0% to 60% of Al. It is shown that in Si doped layers the decay of photoconductivity takes extremely long time (hundreds and thousands seconds, depending on temperature, composition and illumination conditions). Both the kinetics of rise and fall of photoconductivity are best described by stretched exponents. The characteristic decay times are virtually temperature independent for temperatures below 270–290K and have activation energy of 0.14–0.26 eV (depending on composition) for higher temperatures. The decay times become longer with decreased light intensity and increase when above-bandgap light excitation is replaced by subbandgap light excitation (the photocurrent values from which the decay starts being equivalent). The results cannot be quantitatively explained by the effects of changing of the quasi-Fermi level position well known for DX-centers in AlGaAs. No persistent photoconductivity could be observed in high resistivity undoped AlGaN films with 5%, 15% and 25% of Al.

Conversion of Alkoxide Solutions to Oxides: Evaporation of Products

1989 ◽  
Vol 155 ◽  
Author(s):  
R. A. Lipeles ◽  
D. J. Coleman
Keyword(s):  
High Flow ◽  
Drying Rate ◽  
Flow Rates ◽  
Long Time ◽  
Drying Rates ◽  
Drying Conditions ◽  
Kinetics Of ◽  
By Products ◽  
Evaporation Kinetics ◽  
Kinetics Monitoring

ABSTRACTThe evaporation of organic by-products released during drying of 1-mm thick silicon tetramethoxide gels was analyzed using gas chromatography. The evaporation kinetics of methanol depended on the drying rate achieved by flowing dry air over the gel. For drying at flow rates less than 50 cm 3/min, exponential kinetics were observed initially with a long time constant (about 100- to 400-min). For drying rates greater than 70 cm3/min, diffusional (t−1/2) kinetics were observed initially. Cracking of the gel during drying was used to indicate the degree of stress. At low drying rates, minor cracking was observed near the edges of the gel. At high flow rates, extensive cracking was observed in samples that exhibited early t−1/2 kinetics. Monitoring the kinetics of drying is essential to optimizing the drying conditions to minimize stress and cracking in gels.

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