| Thesis Name：Curing and thermal property of boron-containing o-cresol formaldehyde resin |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
Abstract The curing and thermal degradation process of boron-containing o-cresol formaldehyde resin (BOCNR) was studied by infrared spectroscopy (IR) and thermogravimetry analysis (TGA). The results show that hexatomic ring containing coordinate linkage of boron-oxygen formed in the curing process of BOCNR, and the coordinated oxygen atom was offered by phenol hydroxyl. TGA results show that BOCNR have good thermostability and its degradation processes can be divided into three stages. In the second and third stages, the decomposition reactions are all following first mechanism function.
Xia Liya, Gao Jungang, Yu Zhenxia
(Supervision Institution of Quality&Technology, College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China) |
|
| Detail |
| Thesis Name：Morphology and thermal properties of liquid crystalline p-PAEB and its homopolymer |
| Country：[CN] |
Usage：[Chemistry] |
| Remarks： |
Abstract
The unsaturated liquid crystalline (LC) compound of p-phenylene di {4- [2- (allyloxy) ethoxy] benzoate} (p-PAEB) and homopolymer poly(p-PAEB) were synthesized. The liquid crystalline behavior and thermal properties of p-PAEB and poly (p-PAEB) have been studied by polarizing optical microscopic (POM), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), torsional braid analysis (TBA). The results of XRD and POM showed that p-PAEB is smectic texture and the poly(p-PAEB) are nematic texture. The dynamic mechanical properties and glass transition temperature Tg of liquid crystalline polymers network (LCP) were investigated with TBA. |
|
| Detail |
| Thesis Name：Condensation of aryl aldehydes with rhodanine in water media catalyzed by Tween 80 |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
Abstract Condensation reactions of various aryl aldehydes with rhodanine proceeded smoothly in water without any organic solvents to afford the corresponding products at room temperature in excellent yields. The procedure presented has the merits of environmentally benign, simple operation, convenient work-up and moderate to good yields. |
|
| Detail |
| Thesis Name：Electrochemical oxidation of imazethapyr and the monitoring of decomposing process |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
Abstract Methodology for the electrochemical decomposition of imazethapyr using Ti/SnO2-Sb2O5/PbO2 anode is suggested in the paper. The results of an experimental study on the destruction of imazethapyr by electrochemical oxidation in NaCl medium are compared with the data obtained by electrochemical oxidation in Na2SO4 medium. The UV-VIS spectra obtained by process monitoring indicated that the reaction mechanism is different from each other when using different electrolyte. Imazethapyr was mineralized directly when using Na2SO4 as the electrolyte, while a kind of intermediate product was formed rapidly and then mineralized fast when using NaCl as the electrolyte. NaCl was selected as the electrolyte for electrochemical oxidation of imazethapyr and the conditions of electrolysis reaction were optimized in the paper. The process of electrochemical decomposition was monitored by ultra-violet spectrophotometric method. The electrochemical decomposition mechanism of imazethapyr was studied primarily by UV-VIS spectrophotometry and the comparative aerobic biological water treatment test. The effectiveness of the electrochemical pretreatment was proved by the comparative aerobic biological treatment based on the activated sludge process. |
|
| Detail |
| Thesis Name：Reactions of electron-deficient alkynes and allenes under phosphine catalysis |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
The development of some new synthetic reactions derived from nucleophilic addition of phosphines to electron-deficient carbon-carbon triple bonds is described. These reactions show that the phosphine plays the role of a nucleophile as well as an excellent leaving group. The central problem is to generate a 1,3-dipole from atkynoates or allenoates; (2,3-butadienoates) by interaction with various phosphines. This study illuminates the unusual phenomena and shows how this understanding allows control of the reaction.
URL:http://pubs.acs.org/cgi-bin/article.cgi/achre4/2001/34/i07/pdf/ar000253x.pdf |
|
| Detail |
| Thesis Name：Preparation the Polymer microspheres of Electroless nickel plating |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
[Abstract]
The polystyrene micro-spheres in the micron diameter range were made by
polymerizations. The magnetic fine particles were prepared by electroless nickel-plating after sensitization and activation. The concentration of monomer and initiator, the amount of surfactant used, and polymerization temperature will affect the particle size and disparity of microspheres. The amount of nickel deposited on microspheres is strongly dependent on the pH value of plating bath and bath composition. The experimental results have shown that the magnetic fine particles can be made under the suitable temperature of 70℃, stirring rate in 300~400rpm and the pH value is 7 of
plating bath. The nickel-plating thin layer on the spherical particles might have the ability of electromagnetic absorbent. We hope that the electromagnetic absorbent polymeric powders can be made through an appropriate processing.
|
|
| Detail |
| Thesis Name：Chaotic Analysis for Nonautonomous Oscillation Circuit |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
[Abstract]
Recently, based on the computer technique and engineer’s research the nonlinear theory has been progressively developed. Chaos is a main topic of the nonlinear theory with the most use in research. Thus, the oscillator with trigger signal circuit, an important circuit in communication system, is presented in this paper.The frequency shift and multiple frequency oscillation usually be existed in the oscillator. It will decrease the performance of communication system. Generally, the problem is said as noise or interference. In this dissertation,
we try to study in alterative points of view.In this work, the nonlinear analysis of triggered oscillation based on the two-segment criterion. We present experimental and simulated results verify the change of chaos in a non-autonomous circuits.The contribution in this dissertation are: (1) An analytical two-segment
criterion is applied to the third-order non-autonomous circuits; (2) The verification of the influence of trigger signal and the phenomena of injection-lock in a oscillator circuit has been presented; (3) The implementation of chaotic circuits is available to design related chaotic circuits for practicality. |
|
| Detail |
| Thesis Name：Machine Learning Approaches to Modeling the Physiochemical Properties of Small Peptides |
| Country：[CN] |
Usage：[Physiochemical] |
| Remarks： |
Abstract:
Peptide and protein sequences are most commonly represented as a strings: a series of letters selected from the twenty character alphabet of abbreviations for the naturally occurring amino acids. Here, we experiment with representations of small peptide sequences that incorporate more physiochemical information. Specifically, we develop three different physiochemical representations for a set of roughly 700 HIV–I protease substrates. These different representations are used as input to an array of six different machine learning models which are used to predict whether or not a given peptide is likely to be an acceptable substrate for the protease. Our results show that, in general, higher–dimensional physiochemical representations tend to have better performance than representations incorporating fewer dimensions selected on the basis of high information content. We contend that such representations are more biologically relevant than simple string–based representations and are likely to more accurately capture peptide characteristics that are functionally important. |
|
| Detail |
| Thesis Name：Study on simultaneous determination of sugar and nicotine with high performance liquid chromatography |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
Abstract The simultaneous determination of sugar and nicotine with high performance liquid chromatography (HPLC) in tobacco was studied. The sugar and nicotine was extracted from the tobacco samples by ultrasonic oscillation for 30 min with 45 ml of 5％ acetic acid solution. Then, the extract was purified by solid extraction with a Waters Sep-Pak-C18 cartridge. The sugars and nicotine were separated on a Waters Sugar-Pak-1 (6.5×300 mm) cations ion exchange column with 0.05 g.L-1 EDTA calcium disodium salt solution as mobile phase. The sugar was detected with a refractive index detector and the nicotine was detected with an UV detector. The detection limit reachs m g/ml level for sugar and ng/ml level for nicotine. The recoveries of sugars and nicotine were between 97- 102 %. The relative standard derivations of sugars and nicotine were 1.3-2.2%. This method was applied to the determination of Sugars and nicotine in tobacco with good result. |
|
| Detail |
| Thesis Name：Phase behaviour of dihydrazide derivatives with lateral intermolecular hydrogen bonds |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
Abstract Four dissymmetrical dihydrazide, N-(4-alkoxybenzoyl)- N'-(4'-nitrobenzoyl)hydrazine(Cn-NO2) (n = 3, 6, 12, 16), were synthesized and investigated by means of differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide angle X-ray diffraction (WAXD). |
|
| Detail |
