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Thesis Name:PHOTOCHEMICAL SELECTIVITY IN GUANINE-CYTOSINE BASE-PAIR STRUCTURES
Country:[CN] Usage:[PHOTOCHEMICAL]
Remarks: Abstract:
Prebiotic chemistry presumably took place before formation of an oxygen-rich atmosphere and thus under conditions of intense short wavelength UV irradiation. Therefore, the UV photochemical stability of the molecular building blocks of life may have been an important selective factor in determining the eventual chemical makeup of critical biomolecules. To investigate the role of UV irradiation in base-pairing we have studied guanine (G) and cytosine (C) base pairs in the absence of the RNA backbone. We distinguished base-pair structures by IR-UV hole-burning spectroscopy as well as by high-level correlated ab initio calculations. The Watson-Crick structure exhibits broad UV absorption, in stark contrast to other GC structures and other base-pair structures. This broad absorption may be explained by a rapid internal conversion that makes this specific base pair arrangement uniquely photochemically stable.


Author:Abo-Riziq A, Grace L, Nir E, Kabelac M, Hobza P, d
Issue:PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 102 (1): 20-23 JAN 4 2005
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Thesis Name:SURFACE RECOGNITION OF BIOMACROMOLECULES USING NANOPARTICLE RECEPTORS
Country:[CN] Usage:[chemistry]
Remarks: Abstract:
Nanoparticles present a versatile scaffold to target biomacromolecule surfaces via complementary interactions. This review highlights some unique features of nanoparticles that make them particularly attractive resources for biomacromolecular recognition, and displays their use in modulation of structure and function of biomacromolecules.


Author:Verma A, Rotello VM
Issue:CHEMICAL COMMUNICATIONS (3): 303-312 2005
Detail
Thesis Name:THE SLOW-SCALE STOCHASTIC SIMULATION ALGORITHM
Country:[CN] Usage:[CHEMICAL PHYSICS]
Remarks: Abstract:
Reactions in real chemical systems often take place on vastly different time scales, with "fast" reaction channels firing very much more frequently than "slow" ones. These firings will be interdependent if, as is usually the case, the fast and slow reactions involve some of the same species. An exact stochastic simulation of such a system will necessarily spend most of its time simulating the more numerous fast reaction events. This is a frustratingly inefficient allocation of computational effort when dynamical stiffness is present, since in that case a fast reaction event will be of much less importance to the system's evolution than will a slow reaction event. For such situations, this paper develops a systematic approximate theory that allows one to stochastically advance the system in time by simulating the firings of only the slow reaction events. Developing an effective strategy to implement this theory poses some challenges, but as is illustrated here for two simple systems, when those challenges can be overcome, very substantial increases in simulation speed can be realized.


Author:Cao Y, Gillespie DT, Petzold LR
Issue:JOURNAL OF CHEMICAL PHYSICS 122 (1): Art. No. 014116 JAN 1 2005
Detail
Thesis Name:Electrochemical Quartz Crystal Microbalance
Country:[CN] Usage:[Electrochemical]
Remarks: Abstract:
The (E)QCM is a versatile method to estimate real-time mass changes in situ.These mass changes reflect different reactions, such as adsorption, dissolution, or film growth. Toobtain more complete information on the processes occurring on the surface, the (E)QCM can becombined with different analytical techniques, for example, surface spectroscopy, IR absorption, orelectrochemical impedance spectroscopy. Its high sensitivity permits the study of mass changescorresponding to fractions of a monolayer. However, a quartz sensor is also sensitive to thecoupling between its surface and the surrounding environment. For a correct data interpretation, itis important that the effects of viscous loading, double layer structure, surface roughness, andtemperature are taken into consideration. In the field of corrosion, the EQCM has been successfullyapplied to a wide variety of problems. One example is the study of uniform dissolution inidentifying partial currents by comparing the mass loss with the total current. It has also beenused to calculate adsorption isotherms for organic inhibitors. Another application is the study ofpassive films on stainless steels, where it has been shown that a combination with XPS gives thepossibility to study film growth kinetics for alloys with several alloy elements showing widelydifferent chemical behavior.


Author:C.-O. A. Olsson; D. Landolt
Detail
Thesis Name:The development of low aldehyde and super bright PET chips
Country:[CN] Usage:[chemical industry]
Remarks: Abstract: The development process of low aldehyde super bright PET chip was introduced. The methods to reduce the ethanal content in chips were expounded,such as reducing the reaction temperature,decreasing the final polycondensation liquid level properly,stopping using the recovery EG and adding stabilizer. A new production process of modified PET product was provide.


Source:POLYESTER INDUSTRY
Author:SUI Peng-da, XIE Wen-jian,ZHANG Ye
(1.Polyester Plant of Liaoyang Petrochemical Corporation,Liaoyang 111003,China;2.Liaoyang Petrochemical Research Institute of Corporation,Liaoyang 111003,China)
Detail
Thesis Name:Study of the preparation and properties of PET negative ions fiber
Country:[CN] Usage:[Chemical Engineering]
Remarks: Abstract: The surface modified tourmaline powder was added into PET, blended and made granules. Then the mastergrain and PET was spinned according to a certain proportion. By comparison, the effects of tourmaline powder content on chip thermodynamics, fiber crystallization and mechanical properties were studied. The test carried out by the negative ions tester show that the PET fiber with the mass fraction of tourmaline powder of 2% and 4% can release 460 and 480 negative ions per mL ,which is more than twice of that of park environment.


Source:POLYESTER INDUSTRY
Author:WANG Lian-jun, LIU Fang 
(The Chemistry and Chemical Engineering Department of Hunan Institute of Engineering, Xiangtan 411104,China)
Detail
Thesis Name:The current situation and development of China BOPET film industry
Country:[CN] Usage:[BOPET film industry]
Remarks: Abstract:
The development history of China BOPET film industry is introduced. The current situations and the difficult positions of the industry are analysed. By strengthening the new product development ability, leading the consumption, cultivation the market, enhancing the core competitive ability of the enterprise, reorganization of the industry, China BOPET film industry will go out of the difficult position.

Source:POLYESTER INDUSTRY
Author:WANG Le-yue
(Printing and Package Department of Wuhan University, Wuhan 430079,China)
Detail
Thesis Name:Using glycerine the by-product of biological diesel oil as material to produce 1,3 propanediol
Country:[CN] Usage:[Chemical Fiber]
Remarks: Abstract:
Three industrialized synthetic processes of propanediol are recounted. They are acrylaldehyde hydration, ethylene oxide formylation and biological zymolysis methods. The development prospects of China biological diesel oil and the advantages of using glycerine the by-product of biological diesel oil to produce PDO are introduced in detail. The achievement not only develop the optimum process for the low cost production PDO, but also provide a outlet for glycerine the by-product of biological diesel oil.


Source:POLYESTER INDUSTRY
Author:JIN Li-chen
(China Chemical Fiber Industry Association,Beijing 100742,China)
Detail
Thesis Name:The progress in study of melt copolycondensation of poly(ethylene terephthalate)—effect of chemical structure of comonomers on properties and applications
Country:[CN] Usage:[chemistry]
Remarks: Abstract: This article review the research works published in recent years. The effect of chemical structure of comonomers on properties and applications of PET copolyester is described. Two kinds of structure of comonomeric units are considerated: flexible and rigid. Comonomers including flexible and rigid all disturb the regularity of PET macromolecular chain, so the acting force between moleculars of PET is decreased, as a result the melt temperatureθm decreased.All flexible comomers are favour of movement of chain segment, so theθg of this kind of copolyesters decreases. The flexible comonomers promote the crystallization of obtained copolyester, so the crystallization rate increases. The crystallization rate of copolyesters obtained from substituted glycols decreases due to hindered effect of substituted groups. The θg of a great majority of copolyesters obtain from rigid comonomeric units increases. The crystallization rate of all copolyesters from rigid units decreases, even amorphous structure can be obtained. The copolyesters with different properties can be used in different applications.


Source:POLYESTER INDUSTRY
Author:WU Rong-rui(The Material institute of Beijing Institute of Clothing Technology, Beijing 100029,China)
Detail
Thesis Name:Fluorescence Enhancement System of Tb-N-(2-Pyridinyl)ketoacetamide-Et3N-Zn and Its Application
Country:[CN] Usage:[Organic Chemistry]
Remarks: Abstract:
A sensitive fluorescence enhancement system was developed for the determination of zinc (Ⅱ). The fluorescence intensity of the Tb-N-(2-Pyridinyl)ketoacetamide (PKA) system was greatly enhanced by the addition of triethylamine (Et3N) and zinc nitrate in the methanol solution. The excitation and emission wavelengths were 329 nm and 546 nm, respectively. Under optimal conditions, the fluorescence intensities varied linearly with the concentration of Zn2+ in the range of 8.0×10-7-5.0×10-6 M with a detection limit of 9.9×10-8 M.. The interferences of some substances were described. This method was applied to the determination of amounts of Zn2+ in soybean, rice, and wheat, respectively. The results showed that the proposed procedure is a high selective, simple, and rapid method to the determination of Zn2+ ion. The mechanism of fluorescence enhancement was also studied.
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