[Effect of critical process parameters on luminescence properties of Eu2+/Dy3+ co-doped high silica luminescence glass].

In the present work, Eu2+/Dy3+ co-doped high silica glasses with different process parameters were prepared and the effect of critical process parameters including phase separation temperature, solution concentration and sintering temperature on the luminescence properties of Eu2+/Dy3+ co-doped high silica glasses was investigated by means of measuring pore surface parameters of porous glasses, emission spectra, infrared absorption spectra and densities of high silica glasses. Pore structure parameters of porous glass samples and emission spectra of corresponding high silica glass samples with different phase separation temperatures show that the phase separation temperature has indirect effect on luminescence properties of high silica glass by influencing specific surface area value of corresponding porous glass. Specific surface area of porous glass changes when phase separation temperature changes. High silica glass achieves maximum emission intensity when the maximum specific surface area of porous glass is obtained. Luminescence intensity of high silica glass increases when specific surface area of porous glass increases. Emission spectra of high silica glass samples with different solution concentrations show that the emission intensities of Eu2+ and Dy3+ in high silica glass are enhanced with the increase in the Dy3+ concentration in solution; when the Dy3+ concentration is beyond 0.1 mol x L(-1), the emission intensities of Eu2+ and Dy3+ in high silica glass are both decreased due to the occurring of concentration quench of Dy3+ in the glass. Emission spectra and infrared absorption spectra of high silica glass samples with different sintering temperatures show that the emission intensity of high silica glass is increased with the increase in the sintering temperature because the content of residual hydroxyl groups -OH in the glass is decreased; when the sintering temperature is beyond 1000 degrees C, the high silica glass exhibits crystalline and the luminescence intensity decreases.

Phylogenetic and evolutionary analysis of Chinese Leishmania isolates based on multilocus sequence typing.

Leishmaniasis is a debilitating infectious disease that has a variety of clinical forms. In China, visceral leishmaniasis (VL) is the most common symptom, and L. donovani and/or L. infantum are the likely pathogens. In this study, multilocus sequence typing (MLST) of five enzyme-coding genes (fh, g6pdh, icd, mpi, pgd) and two conserved genes (hsp70, lack) was used to investigate the phylogenetic relationships of Chinese Leishmania strains. Concatenated alignment of the nucleotide sequences of the seven genes was analyzed and phylogenetic trees were constructed using neighbor-joining and maximum parsimony models. A set of additional sequences from 25 strains (24 strains belong to the L. donovani complex and one strain belongs to L. gerbilli) were retrieved from GenBank to infer the molecular evolutionary history of Leishmania from China and other endemic areas worldwide. Phylogenetic analyses consolidated Chinese Leishmania into four groups: (i) one clade A population comprised 13 isolates from different foci in China, which were pathogenic to humans and canines. This population was subdivided into two subclades, clade A1 and clade A2, which comprised sister organisms to the remaining members of the worldwide L. donovani complex; (ii) a population in clade B consisted of one reference strain of L. turanica and five Chinese strains from Xinjiang; (iii) clade C (SELF-7 and EJNI-154) formed a population that was closely related to clade B, and both isolates were identified as L. gerbilli; and (iv) the final group, clade D, included Sauroleishmania (LIZRD and KXG-E) and was distinct from the other strains. We hypothesize that the phylogeny of Chinese Leishmania is associated with the geographical origins rather than with the clinical forms (VL or CL) of leishmaniasis. To conclude, this study provides further molecular information on Chinese Leishmania isolates and the Chinese isolates appear to have a more complex evolutionary history than previously thought.

Methotrexate-mediated inhibition of RAD51 expression and homologous recombination in cancer cells.

BACKGROUND: Methotrexate is an inhibitor of folic acid metabolism. Homologous recombination is one of the most important ways to repair double-stranded breaks in DNA and influence the radio- and chemosensitivity of tumor cells. But the relationship between methotrexate and homologous recombination repair has not been elucidated. METHODS: Induction of double-strand breaks by methotrexate in HOS cells is assessed by the neutral comet assay. Inhibition of subnuclear repair foci by methotrexate is measured by immunofluorescence. Western blot and quantitative real-time PCR are conducted to detect whether methotrexate affects the expression level of genes involved in homologous recombination. In addition, we used a pCMV3xnls-I-SceI construct to determine whether methotrexate directly inhibits the process of homologous recombinational repair in cells, and the sensitivity to methotrexate in the Ku80-deficient cells is detected using clonogenic survival assays. RESULTS: The result showed that methotrexate can regulate the repair of DNA double-strand breaks after radiation exposure, and methotrexate inhibition caused the complete inhibition of subnuclear repair foci in response to ionizing radiation. Mechanistic investigation revealed that methotrexate led to a significant reduction in the transcription of RAD51 genes. Treatment with methotrexate resulted in a decreased ability to perform homology-directed repair of I-SceI-induced chromosome breaks. In addition, enhancement of cell death was observed in Ku mutant cells compared to wild-type cells. CONCLUSIONS: These results demonstrate that methotrexate can affect homologous recombination repair of DNA double-strand breaks by controlling the expression of homologous recombination-related genes and suppressing the proper assembly of homologous recombination-directed subnuclear foci.

[Comparative study of uniform-doping and gradient-doping negative electron affinity GaN photocathodes].

High temperature annealing and Cs/O activation are external incentives, while the property of GaN material is internal factor in the preparation of negative electron affinity GaN photocathode. The similarities and differences of the performance of the two structure photocathodes are analysed based on the difference of the structure between uniform-doping and gradient-doping negative electron affinity GaN photocathodes and the changes in photocurrents in activation and the quantum yield after successfully activated of GaN photocathodes. Experiments show that: the photocurrent growth rate is slower in activation, activation time is longer and quantum efficiency is higher after successfully activated of gradient-doping GaN photocathode than those of uniform-doping photocathode respectively. The field-assisted photocathode emission model can explain the differences between the two, built-in electric field of gradient-doping structure creates additional electronic drift to the photocathode surface, and the probability of electrons to reach the photocathode surface is improved correspondingly.

[Investigation of material structure and optical property of transmission-mode GaN photocathode by ultraviolet transmission spectral].

GaN UV photocathode has become a high-performance vacuum ultraviolet detectors in recent years. As the photocathode practical application mode, transmission-type multilayer structure and its optical property have important influences on photocathode photoemission performance. Ultraviolet transmission spectra of transmission-mode GaN photocathode were measured. The optical transmission model of transmission-mode GaN photocathode was built, and based on the model the functional relations of thin film thickness and optical adsorption coefficient with transmission spectral were deduced. The error of calculated GaN epitaxial thickness with respect to actual value is very small, and calculated adsorption coefficients are consistent with reported data. It was shown that material structure and optical property of transmission-mode GaN photocathode can be evaluated accurately by this ultraviolet transmission spectral method.

[Acquisition and analysis of lipophosphonoglycan 1 gene and the noncoding region of Leishmania donovani isolates from hilly foci of China].

A fragment about 2.2 kb located at upstream of lipophosphonoglycan 1 (LPG1) gene of Leishmania donovani isolate from hilly foci of China was obtained by PCR. The nucleotide sequence of the fragment was determined by sequencing. The sequence of the LPG1 gene and its downstream fragment (about 2 kb) was determined by using genome walking method. The above two fragment splicing result showed that the nucleotide sequence of the LPG1 gene with the noncoding region was 4 121 bp (GenBank accession number: HMO27899). The BLAST results showed that the LPG1 gene of L. donovani isolate from hilly foci of China had 72%-78% nucleotide identity compared to that of other Leishmania spp. in GenBank.

[Development of a micro-infrared spectrometer based on pulse infrared light source and two-double light route].

A novel micro infrared spectrometer was designed which is different from traditional grating scanning one. This micro spectrometer introduced an uncooled infrared detector LiTaO3 with high sensitivity and small volume, and a MEMS pulsed infrared light source was adopted as emitter and chopper, which threw off traditional mechanical chopper. Combined with the design of a two-double light route, the volume of micro spectrometer was made even smaller. Primary results show that the design method of micro-infrared spectrometer is feasible, the wavelength range of instrument is wide, from 2000 to 5000 nm, and spectrum bandwidth is about 45 nm, which can be used for the sample analysis, such as plastic films, biologic liquid, environmental gas and so on.

[Microbiochemical analyzer based on continuous spectrum and its test for clinic use].

A microbiochemical analyzer based on continuous spectrum and its test for clinic use are introduced. The principle of splitting behind was adopted to design the micro biochemical analyzer, which has the characteristics of little disorder light, real time collection of continuous spectrum signal (340-770 nm), small volume, light weight, small wastage of sample and reagent and rapidness and direct view of check. It has wide application in the emergency treatment, middling and small hospitals, rescue of battleground, and medicinal research. Representative items for clinic test were selected, such as uric acid, total cholesterin and albumin in our experiments. Comparative test and analysis of the daily check-up samples were made respectively by our microbiochemical analyzer and by the standard one of the hospital (Olympus AU2700, RT-1904C, Beckman LX-20). The test results show that our micro biochemical analyzer can meet the requirement of clinic use.