Effect of solvents on the barrierless reaction in the excited state of cyanine dye

UV－Vis,fluorescence spectroscopy and time resolved spectroscopic technique on picosecond and femto-second scales have been utilized to investigate the effect of steric hindrance and multiple hydroxyl groups of solvents on the barreierless isomerization in excited state of 3,3 ′-di(3-sulfopropyl)thiacyanine triethylamminium salt,The results show that the factors mentioned above may be responsible for a different “short-time behavior “of the bleaching signal on the ground state and nonlinear viscosity dependence of the excited-state lifetime in ispropanol and glycol,These phenomena are distinguished from the situation repored in the long-chained monhydroxyl alcoloh solvents.However,the dye molecule still exhibits the analyzing-wavelength dependence of the observed fluorescence lifetime,that is ,the fluorescence lifetime increases with the increasing of analyzing-wavelength ,The conclusions are in agreement with those drawn from femtosecond upconversion fluorescence experiments and further exemplify the barrierless isomerization model in the excited state.     

Gene cloning and molecular breeding to improve fiber qualities in cotton

Cotton fiber is one of known natural resources comprising the highest purity cellulose. It plays an important role world wide in the textile industry. With the acceleration of spinning speeds and the improvement of the people‘s living level, the demand of improving cotton fiber qualities is getting stronger and stronger. So, making clear the developmental model of fiber cell and elucidating systematically the molecular mechanisms of cotton fiber development and regulation will produce a great significance to make full use of cotton gene resources, raise cotton yield and improve fiber quality, and even develop man-made fiber. In the paper, the status of the gene cloning and the molecular breeding to improve cotton fiber quality were reviewed, the importance and potential of gene cloning related with cotton fiber quality were put forward and the proposal and prospect on fiber quality improvement were made. Using national resources available and through the creative exploration in corresponding research, some international leading patents in genes or markers linked with cotton fiber development having Chinese own intellectual property should be licensed quickly. And they can be used to improve cotton fiber quality in cotton breeding practice.     

On the structure of AP-4 responsive element in the LTR of Jembrana disease virus

As a bovine lentivirus,Jembrana disease virus (JDV) is genetically similar to the bovine immunodeficiency virus (BIV). Unlike other lentiviruses which always have a long incubation period, e.g. 8—10 years for HIV, JDV infection causes an acute illness with shorter incubationpreriod and higher mortality. In the experimentally inocu-lated cattle, the incubation period varied from 8 to 12 d before the onset of clinical symptoms, which is very simi-lar to bovine plague with a high titer of J…     

Construction and numerical tests of the multi-conservation difference scheme

A difference scheme with four conservation properties for solving the spherical barotropic shallow water equations is constructed, based on a proper formulae of the equations and a skillful correction on the spatial difference parts of the semi-discrete equations with which the number of the conservation properties of these equations is increased from three to four. Numerical tests are included, and good results are achieved in this study.     

DNA microarray synthesis by using PDMS molecular stamps (Ⅲ)—— Optimization for the reaction conditions

Optimization for the technological processes of fabricating oligonucleotide microarray by the molecular stamping method is studied in this note. Three factors that affect the pressing coupling reactions of the nucleosides are focused on: the stability of the chemical activities of the reaction solutions, the contamination of the remain of the reactive nucleotides among the different spots on the chip, and the influence of the capping reaction on the hybridization result. The experiments show that the acetonitrile solution of tetrazole and nucleoside monomer could maintain sufficient reactive activity for more than 10 h. An effective method has been used and proved to eliminate the residual reactive nucleosides on chip with small molecules containing hydroxyl group. Finally, the capping step—a regular step in the conventional DNA chemical synthesis can be neglected in our on-chip DNA synthetic process, which would not affect its hybridization results.     

σ-LET curve obtained with heavy ions accelerated by HIRFL

σ-LET curve is one of the important factors for orbital SEU rate prediction. SEU cross sections of static random access memory (SRAM) IDT71256 were obtained with 35 MeV/u ³⁶Ar ions and 15.14 MeV/u ¹³⁶Xe ions, accelerated by Heavy Ion Research Facility in Lanzhou (HIRFL), fitted with Weibull and Lognormal function to obtain the whole σ-LET curve. The SEU rates of IDT71256 in geosynchronous and two sunsynchronous orbits were predicted with fitting parameters.     

Bleaching effect and nonvolatile holographic storage in doubly doped LiNbO<Subscript>3</Subscript>:Fe:Cu crystals

The bleaching effect, i. e. the crystal shows that decoloration after it is illuminated by ultraviolet light, has been observed in congruent LiNbO3:Fe :Cu crystals. Based on this bleaching effect, a new technique including the reco rding phase by two interfering red beams and fixing phase by both UV light and a coherent red beam has been experimentally investigated to realize nonvolatile holographic storage in LiNbO3:Fe:Cu. The results of proof-of-concept experiments confirm that bleaching effect becomes an alternative physical mechanism for nonv olatile holographic storage with high recording sensitivity and weak light-induced scattering noise.     

Experimental study of oil-water interface layers dilatation rheological properties

Oil-water interface layers dilatation rheological properties have been measured with the liquid-liquid interface film pressure measurement apparatus, which was based on the principles of Langmuir film balance. Experimental results show that it is possible to form the interface-associ- ated material caused by the attraction of the dispersion forces at the pure alkane-water interface. The type of material is sensitive to the interfacial pressure. Under the influence of the interfacial pressure, the stability of the interface associated materials decreases with the increase of the number of alkane carbons.     

Analysis of gene expression patterns with cDNA microarray during late stage of spermatogenesis in mice

The differentiation process of round spermatids to spermatozoa during the late stage of spermatogenesis is called spermiogenesis. To explore spermiogenesis-related genes, cDNA microarray was used to study expression patterns of 1176 genes in pachytene spermatocytes, round spermatids and elongating spermatids of Balb/c mice. The results showed that 208 genes were detected in all the three cell types. Most of them were down-regulated from pachytene spermatocytes to round spermatids and elongating spermatids. However, up-regulation of 7 genes expression in round spermatids and 3 genes in elongating spermatids were found. Expression of 7 differentially expressed genes in cDNA arrays was further confirmed by semi-quantitative RT-PCR study. The RT-PCR results indicated that the expression of 6 genes was consistent with that in cDNA arrays, only one gene did not show differential expression by RT-PCR. These results may provide important clues for studying of expression, regulation, and function of spermiogenesis-related genes.     

The genetic diversity of central and peripheral populations of ratlike hamster (<Emphasis Type="Italic">Cricetulus triton</Emphasis>)

The impact of habitat fragmentation and isolation on the genetic diversity of populations has attracted much attention in studies of meta-population and conservation biology. In this work, using the randomly amplified polymorphic DNA (RAPD) technique, we studied the genetic diversity of central, peripheral and peninsular populations of ratlike hamster, which were collected in five locations of the North China Plain and its surrounding areas, in 1999. The study revealed that, i) the genetic diversity of central population of Raoyang County>the sub-central populations of Gu’an County and Taikang County > the peripheral population of Shunyi District>the peninsular population of Mentougou District; ii) the genetic diversities of the five populations were positively correlated to the nearest distances to the peripheral line of population distribution; iii) there were significant differences of gene frequencies of some RAPD fragments among the five populations. More RAPD fragments disappeared in peripheral populations than in central or sub-central populations. The frequencies of two RAPD fragments were correlated to the latitude. This study clearly indicated that the variation of the genetic diversities of the five populations was caused by edge effect and fragmentation through the enhanced inbreeding and genetic drift, and thus supported the view that habitat fragmentation and related edge effect reduce the population genetic diversity.