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| Thesis Name：Chain transfer reaction studies by metallocene mediated |
| Country：[CN] |
Usage：[chemical industry] |
| Remarks： |
[Abstract]
In this work, we demonstrate that by combined case of p-methyl styrene (pMS) and hydrogen as chain transfer agents resulted in pMS terminated syndiotactic propylene (sPP-t-pMS) in the presence of Ph2C(Cp)(Flu)ZrCl2 /MAO catalyst. It has been shown that the molecular weight of the sPP-t-pMS can be accurately
controlled by carefully regulating the hydrogen and propylene pressures as well as regulating the amount of pMS in feed. Detail polymerization condition studies reveal that the molecular weight of sPP-t-pMS is mainly depending on the concentration of pMS.Subsequently, the resulting telechelic polymers, sPP-t-pMS, can be treated with strong Lewis base (e.g. sec-butyl lithium) followed by adding excess of dimethylsilyldichloride to give end-silylated sPP with active chloro end group for coupling with an anionically polymerized block. We successfully applied the above synthetic route for preparing two novel diblock copolymers, mainly,
syndiotactic polypropylene-block-poly-2-vinylpyridine and syndiotactic
polypropylene-block-poly-methyl methacrylate . |
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| Detail |
| Thesis Name：Palladium-mediated copolymerization of cyclic olefins and carbon monoxide : competition between ketone and spiroketal microstructures. |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
[Abstract]
The purpose of this project is to study the copolymerization of carbon
monoxide with cyclic olefines by using a cationic palladium catalyst catalyst composition which are prepared from palladium acetate, a suitable amount of 1,10-phenanthroline, a Bronsted acid ( eg. p-toluenesulfonic acid) and suitable
amount of methanol. The polymerization reactions were conducted at a high pressure of carbon monoxide under various reaction conditions. The resulting
polymers can be isolated collected after completing the polymerization
reaction and after precipitation and collected by filtration. Based on 13C-NMR 、 1H-NMR、MALDI-TOF and GC-MS analyses, the microstructure of the resulting copolymer can be identified. Our results clearly reveal that the microstructures of the resulting copolymers are highly depending on the structure of the cyclic olefins. In the second part of this paper , we focus on the influence of polymer structure and physical properties by 1,4-
Benzoquinone. Finally , a terpolymerization of ethylene , endo-
dicyclopentadiene and carbon monoxide was studied to investingate the
convection between cyclization and the 〝Thorpe-Ingold effect〞. |
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| Detail |
| Thesis Name：Hydrotalcite-supported palladium for reductive coupling of haloaryls to biaryls |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
Abstract A new and efficient heterogeneous catalyst based on palladium particles supported on hydrotalcite was developed for reductive coupling of chloro- and bromo-aryls to biaryls. The catalyst was reusable without obvious loss in catalytic activity. |
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| Thesis Name：Antimicrobial and pesticidal activity of fraxinellone from Dictamnus dasycarpus |
| Country：[CN] |
Usage：[biochemistry] |
| Remarks： |
Abstract By means of solvent partition, preparative TLC and spectral analysis, a main active substance with the biological activity was fraxinellone contained in D.dasycarpus. Its antifeeding rate and mortality of 72h at 0.21% (mass percent) against 3rd armyworm (mythimna separata) were 90.4% and 95.2%, respectively. Then antimicrobial activity of fraxinellone had been tested against 7 kinds of bacteria and 10 kinds of plant diseases. The inhibition rate of fraxinellone at 50ppm reached 100%, 99.8% and 99.8% against Escherichia coli, Staphlococcus aurens and Bacillus megathrium, respectively. Its inhibition rate at 100ppm against Rhizotonia cerealis van der Hoeven apud.Boerema & Verhoeven was 100% and at 50ppm against Colletrichurm lagenarium & verhoeven was 72%. |
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| 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). |
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| Detail |
| Thesis Name：Inhibition of urinary crystal calcium oxalate by sulfated polysaccharide isolated from algae Laminarin |
| Country：[CN] |
Usage：[biochemistry] |
| Remarks： |
Abstract The influence of sulfated polysaccharide (LPS) isolated from marine algae Laminarin on the morphology and phase compositions of urinary crystal calcium oxalate (CaOxa) was investigated by means of scanning electron microscopy and X-ray diffraction. LPS can inhibit the growth of CaOxa crystal, prevent the aggregation of calcium oxalate monohydrate (COM), and induce the formation of calcium oxalate dihydrate (COD). All the three changes can inhibit the formation of CaOxa stones. This result indicated that LPS may be a potential inhibitor to CaOxa urinary stones. |
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| Detail |
| Thesis Name：Palladium-mediated copolymerization of cyclic olefins and carbon monoxide : competition between ketone and spiroketal microstructures. |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
The purpose of this project is to study the copolymerization of carbon
monoxide with cyclic olefines by using a cationic palladium catalyst catalyst composition which are prepared from palladium acetate, a suitable amount of 1,10-phenanthroline, a Bronsted acid ( eg. p-toluenesulfonic acid) and suitable
amount of methanol. The polymerization reactions were conducted at a high pressure of carbon monoxide under various reaction conditions. The resulting
polymers can be isolated collected after completing the polymerization
reaction and after precipitation and collected by filtration. Based on 13C-NMR 、1H-NMR、MALDI-TOF and GC-MS analyses, the microstructure of the resulting copolymer can be identified. Our results clearly reveal that the microstructures of the resulting copolymers are highly depending on the structure of the cyclic olefins. In the second part of this paper , we focus on the influence of polymer structure and physical properties by 1,4-
Benzoquinone. Finally , a terpolymerization of ethylene , endo-
dicyclopentadiene and carbon monoxide was studied to investingate the
convection between cyclization and the 〝Thorpe-Ingold effect〞. |
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| Detail |
| Thesis Name：Oxidation of Propane over Transition Metallic Oxide |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
[Abstract]
Owing to the properties of lower density, larger specific surface area, unique
structure and adsorption, carbon nanotubes (CNTs) has become attractive and
extensively applied in many researcher groups. In recent literatures, it has
an excellent application in catalysis to use CNTs as a support in different
catalytic reactions.
In this study, CNTs are used as a support, and the supported metal oxide
catalysts are prepared by impregnation method to perform with the propane
oxidation reaction. Upon the surface treatment on CNTs, the original catalysts
and the amorphous carbon on CNTs can be removed efficiently and the purity of
CNTs can be improved, specific surface area of CNTs and carboxyl groups can be
increased and produced to make CNTs more hydrophilic. To analyze the effect of
different contents of supported metal (vanadium, molybdenum and chromium)
oxide on the CNTs, BET surface area, TGA, XRD and Raman will be used to
characterize the structural information of CNTs. From the results, the surface
metal oxides may be formed as V2O5, Cr2O3 and MoO3 crystallites, and metal
oxide layers on CNTs surface can be coexisted on the CNTs surface.
The concentration of reaction products was detected by GC analysis and
determine that the products are propene and by-products, such as CO, CO2, CH4,
C2H6 etc. In the catalytic results, the supported chromium oxide catalysts
possess a higher conversion and yields among the supported metal oxide
catalysts. However, the supported molybdenum oxide catalysts possess a higher
selectivity. By increasing temperature, the reaction conversion increases and
selectivity goes lower. With the increase of the oxygen feed ratio, the by-
products CO and CO2 become increasing. In addition, the propane conversion
increases with increasing surface metal oxide concentration in the catalysts
and drop off with further increasing the coverage of surface metal oxide.
Thus, the catalyst properties are related to the concentrations of metal oxide
additive.
In the propane oxidation reaction, the thermal stability of CNTs used as a
support is higher than those on active carbon support, and furthermore, it
possesses higher catalytic effect at higher temperature condition. |
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| Detail |
| Thesis Name：Determination methods for total carbon concentration in water samples |
| Country：[CN] |
Usage：[chemistry] |
| Remarks： |
In this paper, determination methods of total carbon concentration (TC), including total inorganic carbon (TIC) and total organic carbon (TOC) were summarized. TIC determination in natural water samples is essentially vital, especially in sea water samples, for studying the present and future global CO2 air-sea flux. Flow injection analysis (FIA) coupled with a gas diffusion unit (GDU) is proved to be simple, sensitive, rapid and easy to operate for TIC determination. TOC determination is one of the most important works for acquiring knowledge about water and wastewater quality. TOC analysis procedures include two steps, firstly converting the component of organic matter to CO2 and then detecting of the CO2 or carbonate ion in CO2 absorbing solution. |
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| Thesis Name：Present status and applications of membrane bioreactors |
| Country：[CN] |
Usage：[biochemistry] |
| Remarks： |
Membrane bioreactors (MBRs), which integrate membrane with bioreactor, simultaneously hold two functions: biocatalysis and membrane separation. Firstly, their advantages and classifications are involved in this paper. Then various applications of MBR in the food industry, fine chemical, pharmaceutical, biomedical productions and environmental treatment are enumerated respectively. These applications obviously denote the potential advantages of MBRs over those in conventional bioreactors (e.g. batch reactor). Finally, current technical challenges facing with in commercial applications of MBRs are described and a perspective is given. |
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