Cononsolvency Phenomena of Poly(N-Isopropylacrylamide) in Mixed Solvents at Different Temperatures

2011 ◽  
Vol 332-334 ◽  
pp. 1752-1755
Author(s):  
Xiao Xia Qiu ◽  
Jie Sun ◽  
Shu Jie Tong ◽  
Shi Jia Wang ◽  
Li Yuan Wu ◽  
...  
Keyword(s):  
Mixed Solvents ◽  
Volume Ratio ◽  
Polymer Gels ◽  
High Water ◽  
Polymer Chains ◽  
Temperature Dependent ◽  
Different Temperatures ◽  
Ft Ir ◽  
Water Fractions ◽  
Increasing Temperature

N-isopropylacrylamide was synthesized in a mixture of DMF and THF ( 7:3 in volume ratio) and characterized by FT-IR. The behavior of poly(N-isopropylacrylamide) chain was studied by spectrometer in mixtures of water with DMF and THF. Cononsolvency phenomena were found to be temperature-dependent, as demixing occurred upon increasing temperature. A significant shrinkage of polymer chains and deswelling of polymer gels, followed by phase separation, were observed for high water fractions.

Experimental and Numerical Study on Dynamic Properties of Viscoelastic Microvibration Damper Considering Temperature and Frequency Effects

2016 ◽  
Vol 11 (6) ◽  
Author(s):  
Chao Xu ◽  
Zhao-Dong Xu ◽  
Teng Ge ◽  
Ya-Xin Liao
Keyword(s):  
Loss Factor ◽  
Numerical Study ◽  
Dynamic Properties ◽  
Frequency Effect ◽  
Solid Model ◽  
Temperature Dependent ◽  
Frequency Effects ◽  
Proposed Model ◽  
Different Temperatures ◽  
Increasing Temperature

This work presents an experimental and numerical study on the dynamic properties of viscoelastic (VE) microvibration damper under microvibration conditions at different frequencies and temperatures. The experimental results show that the storage modulus and the loss factor of VE microvibration damper both increase with increasing frequency but decrease with increasing temperature. To explicitly and accurately represent the temperature and frequency effects on the dynamic properties of VE microvibration damper, a modified standard solid model based on a phenomenological model and chain network model is proposed. A Gaussian chain spring and a temperature-dependent dashpot are employed to reflect the temperature effect in the model, and the frequency effect is considered with the nature of the standard solid model. Then, the proposed model is verified by comparing the numerical results with the experimental data. The results show that the proposed model can accurately describe the dynamic properties of VE microvibration damper at different temperatures and frequencies.

Impact of temperature on biodegradation of bulk and trace organics during soil passage in an indirect reuse system

2008 ◽  
Vol 57 (7) ◽  
pp. 987-994 ◽  
Author(s):  
S. Gruenheid ◽  
U. Huebner ◽  
M. Jekel
Keyword(s):  
Organic Compounds ◽  
Soil Column ◽  
Degradation Behavior ◽  
Trace Organic Compounds ◽  
Temperature Dependent ◽  
Column System ◽  
Trace Organics ◽  
Mineralization Potential ◽  
Different Temperatures ◽  
Increasing Temperature

Investigations on the behavior of bulk organics and trace organic compounds in a temperature controlled soil column system are reported. Objective of the research was to assess the importance of temperature for the degradation of bulk and trace organics. The analysis of the bulk organic behavior showed a fast mineralization of easily degradable organic carbon in the first few centimetres of the columns, which does not seem to be temperature-dependent. Along the further infiltration path an influence of the different temperatures on the bioactivity was clearly visible. However, a significant increase of mineralization potential of bulk organic compounds with increasing temperature was shown. The monitoring of the single organic pollutants Iopromide, Sulfamethoxazole and naphthalenedisulfonic acids showed that temperature has an influence on the degradation behavior of the monitored compounds. In most cases higher temperatures increased the mineralization potential.

scholarly journals Study of the Effect of pH and Supersaturation on the Kinetics and Rate of Solid Layer Formation at External Sides of Thermal Heat Transfer Tubes

2015 ◽  
Vol 09 (2) ◽  
Keyword(s):  
Growth Rate ◽  
Calcium Carbonate ◽  
Layer Growth ◽  
Basic Medium ◽  
Temperature Dependent ◽  
Scale Layer ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Layer Composition ◽  
Scale Deposition

The formation of scale layers at the external sides of heated tubes at situations comparable with a Multi Effect Distiller (MED) desalination processes is experimentally studied. The growth of scale layer was measured at different temperatures, pH levels and salinities. The measured scale deposition rate data were correlated to the calcium carbonate supersaturation according to a power low kinetics. It was found that the growth rate order (n) with respect to supersaturation is strongly temperature dependent. It decreases with increasing temperature. The calculated value of activation energy of scale layer growth is Ea = 33360 J/mol. The scale layer growth was found to be strongly dependent on pH. It increases in the basic medium. The salinity was found to be significant in determining the growth rate of scale layer. The scale layer composition is affected by temperature. It was found that calcium carbonate is dominant at high temperatures (80 °C). calcium sulfate deposited besides calcium carbonate at lower temperatures (60-70 °C).

Oviposition model of Amblyseius swirskii Athias-Henriot in prey system (Tetranychus urticae Koch)

2020 ◽  
Vol 25 (10) ◽  
pp. 1857-1866
Author(s):  
Azadeh Farazmand ◽  
Masood Maafi Amir
Keyword(s):  
Survival Rate ◽  
Tetranychus Urticae ◽  
Mass Rearing ◽  
Weibull Function ◽  
Sigmoid Function ◽  
Amblyseius Swirskii ◽  
Temperature Dependent ◽  
Non Linear Equation ◽  
Different Temperatures ◽  
Increasing Temperature

In this study, temperature-dependent oviposition model of Amblyseius swirskii Athias-Henriot fed by Tetranychus urticae Koch as prey was developed. In order to obtain data for the model, the longevity, fecundity and survivorship of adult females of A. swirskii were recorded at seven different temperatures (15, 20, 25, 27.5, 30, 32.5 and 35 °C) all at 60±5% RH and a photoperiod of 16:8h (L; D) in growth chamber. The longevity of females decreased with increasing temperature; the maximum at 15°C (84±3.24 days) and the minimum at 32.5°C (22.48±0.31 days). The female adult developmental rates (1/median longevity) was described by Sharpe and DeMichele model (r2=0.99). The highest and the lowest fecundity were observed at 25°C (22.63±0.76 eggs/female) and 15°C (9.4±0.67 eggs/female), respectively. The oviposition model comprised of three functions: temperature-dependent fecundity, age-specific cumulative oviposition rate and age-specific survival rate. The best model of temperature-dependent fecundity was described by a non-linear equation (extreme value function) (r2=0.98). Similarly, the best model of age-specific cumulative oviposition was described by the two-parameter Weibull function (r2=0.94). Eventually, the best model of age-specific survival rate was described by sigmoid function (r2=0.97). Amblyseius swirskii has ability to control pests such as thrips, whiteflies and two-spotted spider mites and can grow even in low temperatures. Therefore, this mite can be active at the beginning of spring season. Temperature-dependent oviposition model of A. swirskii can determine optimal temperature for mass-rearing and predict seasonal population dynamic of this predatory mite in greenhouses. Finally, the greenhouse data can validate this model in future.

scholarly journals Synthesis, Characterization and Electrical Properties of ZnFe2O4 Nanoparticles

2021 ◽  
Vol 7 (2) ◽  
pp. 946-948
Author(s):  
Md Ashfaq Hussain ◽  
S Sindhu ◽  
B Raghunanda ◽  
S. Molakeri Ajai Kumar
Keyword(s):  
Ac Conductivity ◽  
Zinc Ferrite ◽  
Size Range ◽  
Combustion Method ◽  
Dc Conductivity ◽  
Temperature Dependent ◽  
Particle Size Range ◽  
Ft Ir ◽  
Znfe2o4 Nanoparticles ◽  
Increasing Temperature

Zinc ferrite (ZnFe2O4) nanoparticles were prepared by combustion method. The FT-IR, XRD and SEM with EDS were used to characterize the prepared sample. The characterization results confirm the successful synthesis of ZnFe2O4 nanoparticles with the particle size range of 24 – 30 nm. The temperature dependent DC conductivity of the sample has been studied in the temperature range 30-175 °C and AC conductivity was investigated between the frequencies of 10 Hz and 10 MHz. DC conductivity of the sample was increased while increasing temperature and AC conductivity was increased as the frequency increased.

Temperature-dependent heterojunction device characteristics of n-ZnO nanorods/p-Si assembly

2020 ◽  
Vol 10 (1) ◽  
pp. 29-36
Author(s):  
Rashad I. Badran ◽  
Yas Al-Hadeethi ◽  
Ahmad Umar ◽  
Saleh H. Al-Heniti ◽  
Bahaaudin M. Raffah ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Hexagonal Phase ◽  
Zno Nanorods ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Different Temperatures ◽  
Evaporation Technique ◽  
Wurtzite Hexagonal Phase ◽  
Heterojunction Device ◽  
Increasing Temperature

Heterojunction diode based on n-ZnO nanorods/p-Silicon (Si) assembly was fabricated, examined and reported here. Horizontal quartz tube thermal evaporation technique was used for the growth of ZnO nanorods on Si substrate. The nanorods were characterized by several techniques to examine the structural, morphological, scattering and electrical properties. Wurtzite hexagonal phase of the grown aligned nanorods was observed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The appearance of a sharp Raman peak at 438 cm–1 was observed and it is related to the E2(high) mode of the wurtzite hexagonal phase of ZnO. The electrical properties of the fabricated heterojunction assembly were examined at different temperatures (298∼398 K) in both reverse and forward biased conditions, and a good stability was observed over the entire temperature range. A reduction in the turn-on and breakdown voltage was observed with increasing temperature. By increasing the temperature, the effective potential barrier height was increased, while quality factor was decreased. The observed activation energy was found to be ∼93.4 meV, higher than the exciton binding energy of ZnO.

Temperature-Dependent Current-Voltage Characteristics in ZnO Based Schottky Diodes

2014 ◽  
Vol 894 ◽  
pp. 391-395
Author(s):  
Hog Young Kim ◽  
Ahrum Sohn ◽  
Dong Wook Kim
Keyword(s):  
Schottky Diodes ◽  
Interface State ◽  
State Density ◽  
Current Transport ◽  
Temperature Dependent ◽  
Conduction Path ◽  
Current Voltage ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Surface Conduction

Using currentvoltage (IV) measurements, the temperature-dependent current transport in Ag/Zn-polar ZnO Schottky diodes was investigated. Both the series and shunt resistances of the diode were altered at the different temperatures, which were related to the amount of free carriers and the formation of a vacuum-activated surface conduction path, respectively. The reverse biased current transport was associated with a thermally assisted tunneling field emission of carriers and the Poole-Frenkel effect, for higher and lower voltages, respectively. The average interface state density decreased with increasing temperature, which was due to a result of molecular restructuring and reordering and/or variation of the ideality factor with temperatures across the Ag/ZnO interface.

Circadian Rhythm of Locomotion and its Temperature Dependence in Blattella Germanica

1971 ◽  
Vol 54 (1) ◽  
pp. 187-198
Author(s):  
HANS DREISIG ◽  
ERIK TETENS NIELSEN
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Temperature Dependence ◽  
Blattella Germanica ◽  
Temperature Dependent ◽  
Continuous Darkness ◽  
Expected Time ◽  
Different Temperatures ◽  
Free Running ◽  
Increasing Temperature

1. The activity in Blattella germanica was investigated under standard conditions. Periods of latency and increment were recognized. 2. The free-running rhythm in continuous darkness was determined at different temperatures and showed about the same period. The free-running rhythm in continous light could not be determined unless the light intensity was extremely low. 3. The period of activity was not released immediately after a change from light to darkness if this was advanced in relation to the normal time. The activity was then only slightly advanced. 4. Delay of the onset of darkness caused the activity to diminish gradually after the usual time of change from light to dark. 5. If the temperature was lowered some time before the expected time of activity in continuous darkness the activity was advanced much more than normally. If the temperature was raised the activity was delayed. 6. Based upon these and other studies, a theory is advanced which explains the activity rhythms in insects as being the result of the interaction between a gradually increasing, temperature-dependent sensitization and different thresholds of release determined by light and temperature. A theory is propounded concerning the temperature-independence of the free-running rhythm in continuous darkness, assuming a temperature-dependent threshold of release.

scholarly journals A Comparative Electrochemical and Morphological Investigation on the Behavior of NiCr and CoCr Dental Alloys at Various Temperatures

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 256
Author(s):  
Florentina Golgovici ◽  
Mariana Prodana ◽  
Florentina Gina Ionascu ◽  
Ioana Demetrescu
Keyword(s):  
Low Temperatures ◽  
Artificial Saliva ◽  
Electrochemical Stability ◽  
Morphological Investigation ◽  
Dental Alloys ◽  
Ion Release ◽  
Icp Ms ◽  
Different Temperatures ◽  
Good Concordance ◽  
Increasing Temperature

The purpose of our study is to compare the behavior of two reprocessed dental alloys (NiCr and CoCr) at different temperatures considering the idea that food and drinks in the oral cavity create various compositions at different pH levels; the novelty is the investigation of temperature effect on corrosion parameters and ion release of dental alloys. Electrochemical stability was studied together with morphology, elemental composition and ions release determination. The results obtained are in good concordance: electrochemistry studies reveal that the corrosion rate is increasing by increasing the temperature. From SEM coupled with EDS, the oxide film formed on the surface of the alloys is stable at low temperatures and a trend to break after 310K. ICP-MS results evidence that in accordance with increasing temperature, the quantities of ions released from the alloys immersed in artificial saliva also increase, though they still remain small, less than 20 ppm.

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