Effects of Synthesis-Solvent on Characteristics of Poly(N-Isopropylacrylamide) Hydrogels Synthesized by Frontal Polymerization

2011 ◽  
Vol 295-297 ◽  
pp. 1193-1197 ◽  
Author(s):  
Qiao Feng ◽  
Ling Zhi Du ◽  
Qing Zhi Yan ◽  
Chang Chun Ge
Keyword(s):  
Mixed Solvent ◽  
Mixed Solvents ◽  
Frontal Polymerization ◽  
Swelling Behavior ◽  
Polymerization Process ◽  
Swelling Ratio ◽  
The One ◽  
Short Time ◽  
Responsive Hydrogels

The synthesis of thermo-responsive hydrogels poly(N-isopropylacrylamide )(PNIPAm) by frontal polymerization (FP) was carried out in four mixed solvents, i.e. dimethylsulfoxide (DMSO) mixing with water, ethanol, tetrahydrofuran (THF) and acetone, respectively. The influences of mixed solvent on frontal parameters, pore morphologies, swelling behavior of PNIPAm hydrogels were investigated. The pore of PNIPAm hydrogel synthesized in THF/DMSO was observed a big honeycomb cells, others were channel-like cells. Furthermore, the sample obtained in THF/DMSO had higher swelling ratio as compared to others, and the one synthesized in Water/DMSO showed the lowest. Above results indicated that fine-tuned poly(N-isopropylacrylamide) hydrogels can be prepared in short time and with easy protocol by adjusting mixed solvents in frontal polymerization process.

Porous Poly(N-Isopropylacrylamide) Gels Frontal Polymerized in Mixed Solvents of Ethanol and Dimethylsulfoxide

2012 ◽  
Vol 554-556 ◽  
pp. 240-243
Author(s):  
Qiao Feng ◽  
Ya Qi Zhao ◽  
Xiang Chen
Keyword(s):  
Porous Structure ◽  
Mixed Solvent ◽  
Mixed Solvents ◽  
Mixed Media ◽  
Frontal Polymerization ◽  
Swelling Ratio ◽  
Response Behavior ◽  
Ethanol Mixture ◽  
Responsive Hydrogels ◽  
Porous Poly

The thermo-responsive hydrogels poly(N-isopropylacrylamide) (PNIPAm) were synthesized by frontal polymerization (FP) in dimethylsulfoxide (DMSO) and ethanol mixture. The effects of composition of synthesis-solvent on FP feature and porous morphologies as well as their response behavior of the final products were studied. PNIPAm hydrogel synthesized in mixture exhibited a porous structure, which was responsible for its higher swelling ratio. Moreover, an improvement in swelling capability of the final PNIPAm hydrogel was found when the ethanol content in mixed media was elevated. The approach, frontal polymerization in mixed solvent, reported here provides a promising option to synthesize porous intelligent hydrogels PNIPAm.

The Effects of Amines on the Esterase Activities of Thrombin and Thrombokinase and on Several Clotting Tests

1974 ◽  
Vol 31 (02) ◽  
pp. 309-318
Author(s):  
Phyllis S Roberts ◽  
Raphael M Ottenbrite ◽  
Patricia B Fleming ◽  
James Wigand
Keyword(s):  
Choline Chloride ◽  
Polymerization Process ◽  
Ammonium Bromide ◽  
Bovine Thrombin ◽  
One Stage ◽  
Human Proteins ◽  
Rate Of Hydrolysis ◽  
The One ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Summary1. Choline chloride, 0.1 M (in 0.25 M Tris. HCl buffer, pH 7.4 or 8.0, 37°), doubles the rate of hydrolysis of TAME by bovine thrombokinase but has no effect on the hydrolysis of this ester by either human or bovine thrombin. Only when 1.0 M or more choline chloride is present is the hydrolysis of BAME by thrombokinase or thrombin weakly inhibited. Evidence is presented that shows that these effects are due to the quaternary amine group.2. Tetramethyl ammonium bromide or chloride has about the same effects on the hydrolysis of esters by these enzymes as does choline chloride but tetra-ethyl, -n.propyl and -n.butyl ammonium bromides (0.1 M) are stronger accelerators of the thrombokinase-TAME reaction and they also accelerate, but to a lesser degree, the thrombin-TAME reaction. In addition, they inhibit the hydrolysis of BAME by both enzymes. Their effects on these reactions, however, do not follow any regular order. The tetraethyl compound is the strongest accelerator of the thrombokinase-TAME reaction but the tetra-ethyl and -butyl compounds are the strongest accelerators of the thrombin-TAME reaction. The ethyl and propyl compounds are the best (although weak) inhibitors of the thrombokinase-BAME and the propyl compound of the thrombin-BAME reactions.3. Tetra-methyl, -ethyl, -n.propyl and -n.butyl ammonium bromides (0.01 M) inhibit the clotting of fibrinogen by thrombin (bovine and human proteins) at pH 7.4, imidazole or pH 6.1, phosphate buffers and they also inhibit, but to a lesser degree, a modified one-stage prothrombin test. In all cases the inhibition increases regularly as the size of the alkyl group increases from methyl to butyl. Only the ethyl com pound (0.025 M but not 0.01 M), however, significantly inhibits the polymerization of bovine fibrin monomers. It was concluded that inhibition of the fibrinogen-thrombin and the one-stage tests by the quaternary amines is not due to any effect of the com pounds on the polymerization process but probably due to inhibition of thrombin’s action on fibrinogen by the quaternary amines.

Der Erzieher als Manager

2019 ◽  
Vol 95 (4) ◽  
pp. 517-530
Author(s):  
Diana Lohwasser
Keyword(s):  
Educational Process ◽  
The Other ◽  
Critical View ◽  
Other Hand ◽  
The One ◽  
Short Time ◽  
Time Diagnosis

Abstract The Educator as a Manager. A Critical View In the following article tasks and motifs of the educator as manager are described. It is clear that there are other educator metaphors and associated behaviors. To some extent, the actions of the different educator metaphors overlap, but they differ in their purpose and perspective on the educational process and the person to be educated. First, a short time diagnosis is made, which describes the context of this metaphor of the educator as manager. Subsequently, on the one hand, the various motifs, tasks and objectives of an educator as manager are discussed. On the other hand, it is asked if it is possible in the current discourse to take a different perspective on the educational process.

scholarly journals Deep Learning Approach for Vibration Signals Applications

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3929
Author(s):  
Han-Yun Chen ◽  
Ching-Hung Lee
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Parameters Optimization ◽  
Frequency Spectra ◽  
Vibration Signals ◽  
Bearing Faults ◽  
Time Frequency ◽  
And Performance ◽  
The One ◽  
Short Time

This study discusses convolutional neural networks (CNNs) for vibration signals analysis, including applications in machining surface roughness estimation, bearing faults diagnosis, and tool wear detection. The one-dimensional CNNs (1DCNN) and two-dimensional CNNs (2DCNN) are applied for regression and classification applications using different types of inputs, e.g., raw signals, and time-frequency spectra images by short time Fourier transform. In the application of regression and the estimation of machining surface roughness, the 1DCNN is utilized and the corresponding CNN structure (hyper parameters) optimization is proposed by using uniform experimental design (UED), neural network, multiple regression, and particle swarm optimization. It demonstrates the effectiveness of the proposed approach to obtain a structure with better performance. In applications of classification, bearing faults and tool wear classification are carried out by vibration signals analysis and CNN. Finally, the experimental results are shown to demonstrate the effectiveness and performance of our approach.

Acid Volatile Sulfide (AVS) and Simultaneously Extracted Metals (SEM) in Surface Sediments of Chaohu Lake, Anhui Province, China

2013 ◽  
Vol 779-780 ◽  
pp. 1213-1219
Author(s):  
Shu Qin Chen ◽  
Lei Zhang ◽  
Zhao Sheng Chu ◽  
She Rong Hu
Keyword(s):  
Surface Sediments ◽  
Local Scale ◽  
Acid Volatile Sulfide ◽  
Anthropogenic Factors ◽  
Chaohu Lake ◽  
Lake Surface ◽  
Different Seasons ◽  
The One ◽  
Short Time ◽  
Spot 5

At present there are few studies on the AVS and SEM in sediments of Chaohu Lake. Most of the previous studies on heavy metals based on the one time, the short-time or a local-scale survey. In this paper, [AVS] and [SEM] in Chaohu Lake surface sediments were studied for different seasons in 2007, 2008 and 2009. The results showed that: (a) The three-year average of [AV and [ΣSE in surface sediments of Chaohu Lake is 4.2μmolg-1and 2.31μmolg-1, respectively. The maximum of [AV appears on spot 5 (14.845μmolg-1) in summer while the minimum appears on spot 9 (0.13μmolg-1) in winter. (b) In spot 5 which near the estuary of Yuxi River, three-year average of [SE was the maximum (5.81μmolg-1), and the minimum of [ΣSE (0.07μmolg-1) appears on spot 8 which locates in the middle of Chaohu Lake. In spot 13 the [ΣSEM]-[AVS]=3.2>2 and [ΣSEM]/[AVS]=4.45>2.34 indicate that heavy metal contaminants from Hefei city have threatened the biosafety of Chaohu Lake. (c) The spatial autocorrelation of SEMCdis weak, which indicates that spatial distribution of SEMCdis determined by anthropogenic factors rather than sediments' own attribute. Chaohu Lake has been heavily polluted by Cd from no-point source and electronic electroplating industry.

CLASSICAL DIFFUSION AND QUANTAL LOCALIZATION OF A KICKED PARTICLE IN A WELL

1988 ◽  
Vol 02 (01) ◽  
pp. 103-120 ◽  
Author(s):  
AVRAHAM COHEN ◽  
SHMUEL FISHMAN
Keyword(s):  
Diffusion Coefficient ◽  
Classical Limit ◽  
Approximate Formula ◽  
Quantum Systems ◽  
Potential Well ◽  
Diffusive Growth ◽  
Classical Chaos ◽  
The One ◽  
Short Time ◽  
Infinite Potential Well

The classical and quantal behavior of a particle in an infinite potential well, that is periodically kicked is studied. The kicking potential is K|q|α, where q is the coordinate, while K and α are constants. Classically, it is found that for α > 2 the energy of the particle increases diffusively, for α < 2 it is bounded and for α = 2 the result depends on K. An approximate formula for the diffusion coefficient is presented and compared with numerical results. For quantum systems that are chaotic in the classical limit, diffusive growth of energy takes place for a short time and then it is suppressed by quantal effects. For the systems that are studied in this work the origin of the quantal localization in energy is related to the one of classical chaos.

scholarly journals Natural product mixture analysis by matrix-assisted DOSY using Brij surfactants in mixed solvents

RSC Advances ◽  
2014 ◽  
Vol 4 (79) ◽  
pp. 42029-42034 ◽  
Author(s):  
Mariano G. S. Vieira ◽  
Nilce V. Gramosa ◽  
Nágila M. P. S. Ricardo ◽  
Gareth A. Morris ◽  
Ralph W. Adams ◽  
...  
Keyword(s):  
Natural Product ◽  
Mixed Solvent ◽  
Mixed Solvents ◽  
Mixture Analysis ◽  
Surfactant Micelles ◽  
Product Mixture ◽  
Solvent Systems ◽  
Nmr Signals

Brij surfactant micelles in mixed solvent systems aid resolution of natural product NMR signals in diffusion-ordered spectroscopy.

scholarly journals A review on conductometric studies of electrolytes in mixed solvent systems to understand ion-ion and ion-solvent interactions

2020 ◽  
Vol 10 (3) ◽  
pp. 5355-5360
Keyword(s):  
Mixed Solvent ◽  
Mixed Solvents ◽  
Chemical Properties ◽  
Electrolyte Solutions ◽  
Molar Conductance ◽  
Extensive Literature ◽  
Solvent Interactions ◽  
Physico Chemical ◽  
Wide Range ◽  
Solvent Systems

The study of ion- solvent interaction is of much importance to investigate the nature of different solutions. Measurement of electrical conductivity and evaluation of physico-chemical properties, such as molar conductance, limiting molar conductance, ion-pair association, Walden product etc. shade light on different intermolecular interactions present in electrolyte solutions. Solvation properties can be varied by mixing two or more solvents. An extensive literature survey on conductometric studies has been carried out on different electrolytes dissolved in a wide range of mixed solvent systems. The reported results show that strong solute-solute, solute-solvent and solvent-solvent interactions are responsible for the physico- chemical behavior of a solution in mixed solvents.

scholarly journals Vascular Endothelial Growth Factor Concentration in Brain of Rat Treated with Anaerobic Exercises

2015 ◽  
Vol 4 (3) ◽  
pp. 201
Author(s):  
Rostika Flora ◽  
Muhammad Zulkarnain ◽  
Yuliana Ardi ◽  
Esti Sorena ◽  
Roslina Wati ◽  
...  
Keyword(s):  
Wistar Rat ◽  
Anaerobic Exercise ◽  
Control Group ◽  
Vascular Endothelial ◽  
Exercise Frequency ◽  
Treatment Groups ◽  
The One ◽  
Short Time ◽  
Endothelial Growth Factor ◽  
Brain Tissues

Anaerobic  exercise is a high-intensity exercise that needs quick energy supplies obtained in a very short time. However, this exercise may result in tissue hypoxia which is characterized by the increase of HIF-1α concentration. The presence of HIF-1α will induce the secretion of VEGF and, eventually, trigger angiogenesis. Nevertheless, it is still unclear whether anaerobic exercise will also cause hypoxia in which this condition will increase the concentration of VEGF in brain tissues. The aim of this study was to find out the effect of anaerobic exercise frequency towards VEGF concentration of Wistar rat brain tissues.  Brain tissues were taken from rats treated with anaerobic exercise using treadmill. This exercise was given in different frequencies; one time, three times, and seven times a week.  The data collected were analyzed using independent t-test. The results of this study showed that anaerobic  exercise done once a week could significantly increase VEGF concentration (p &lt; 0.05) if compared with the one in control group (95.21 ± 31.99 v.s. 63.36 ± 11.01 pg/mL). Meanwhile, VEGF concentration of treatment groups given exercise three times a week (47.97 ± 10.68 pg/mL) and seven times a week (40.56 ± 13.98 pg/mL) showed a significant decrease if compared with that of control group (63.36 ± 11.01 pg/mL). Anaerobic  exercise affected VEGF concentration as an indicator of angiogenesis in brain tissue of wistar rats.

scholarly journals Mixed Solvents in Multi-Layer Ceramic Capacitors (MLCC) Elec-Tronic Paste and Their Effects on the Properties of Organic Vehicle

2021 ◽  
Author(s):  
Ruolong Gan ◽  
Junrong Li ◽  
Xiuhua Cao ◽  
Jun Huang ◽  
Liying Qian
Keyword(s):  
Mixed Solvent ◽  
Mixed Solvents ◽  
Nitrogen Atmosphere ◽  
Carbon Residue ◽  
Solubility Parameters ◽  
Multilayer Ceramic Capacitors ◽  
Organic Vehicle ◽  
Thermogravimetric Analyzer ◽  
Ceramic Capacitors ◽  
Multilayer Ceramic

The copper end paste used in multilayer ceramic capacitors sintered in nitrogen atmosphere will lead to carbon residue of organic vehicle, which will lead to the reduction of electrode conduc-tivity and high scrap rate. With an attempt to leave no residue in the sintering, the compatibility of solvents and thickeners should be improved because it has an important influence on the hi-erarchical volatilization and carbon residue of organic vehicles. In this work, the volatility of different solvents was compared and several solvents were mixed in a definite proportion to prepare an organic vehicle with polyacrylate resins. The hierarchical volatility and solubility parameters of mixed solvents were adjusted effectively by changing proportions of different components, the thermogravimetric curves of resins and organic vehicles were measured by thermogravimetric analyzer, the effect of solubility parameter on the dissolvability of resins in the solvent and the residual of organic vehicles were studied. Results showed that the hierar-chical volatilization of solvents can be obtained by mixing different solvents; the intrinsic vis-cosity of the organic vehicle is higher and the thermal decomposition residue of polyacrylate resins is lower when the solubility parameters of mixed solvents and polyacrylate resins are closer. The low residual sintering of organic vehicles can be achieved by using the mixed solvent with hierarchical volatility and approximate solubility parameters as resins.

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