Evolution of intrinsic defects and ring structures on the surface of fused silica optics after CO2 laser conditioning.

Recently and interestingly, experiments show that the CO2 laser conditioning can significantly increase the laser-induced damage threshold (LIDT) of fused silica optics, but its underlying mechanism has not been clearly revealed. This Letter reports the experimental studies on the evolution of the intrinsic point defects and intrinsic ring structures on the surface of fused silica optics under the CO2 laser irradiation. The laser conditioning can effectively reduce the intrinsic defect contents in the surface layer of mechanically processed fused silica. However, the suppression effect of defects can be affected by the initial surface state. If there are micro-cracks on the component surface, the effect of the laser conditioning would be limited. The evolution of the intrinsic ring structures indicate that most of the intrinsic defects tend to recombine as short (Si-O)n ring structures during the laser healing of the micro-fractures. The observed recombination behavior and suppression of the intrinsic defects can help find out the reason for the increase of the LIDT of the fused silica optics.

Bending effects on lasing action of semiconductor nanowires.

High flexibility has been one of advantages for one-dimensional semiconductor nanowires (NWs) in wide application of nanoscale integrated circuits. We investigate the bending effects on lasing action of CdSe NWs. Threshold increases and differential efficiency decreases gradually when we decrease the bending radius step by step. Red shift and mode reduction in the output spectra are also observed. The bending loss of laser oscillation is considerably larger than that of photoluminescence (PL), and both show the exponential relationship with the bending radius. Diameter and mode dependent bending losses are investigated. Furthermore, the polarizations of output can be modulated linearly by bending the NWs into different angles continuously.

[The preparation and the in vitro release of OANO-1 microspheres].

OBJECTIVE: To prepare OANO-1 microspheres and test their release in vitro. METHOD: OANO-1 microspheres were made by W/O/W-liquid drying process. The surface morphology of the microspheres was observed by SEM. The mean diameter and the size distribution of microspheres, the drug loading and the incorporation efficiency were examined. The release of OANO-1 microspheres in vitro was examined by small cup method. The accumulated release percent of OANO-1 microspheres was examined. RESULT: The OANO-1 microspheres were regular in their morphology. The average particle size was 8.59 microm with over 90% of the microspheres being in the range of 1-12 microm. The drug loading and the incorporation efficiency were 48.39% and 19.32% respectively. The accumulated release percent of OANO-1 microspheres was 78.4% after 108 h. The release half-life t1/2 was 40.8 h and Higuchi equation was Y = 0.1326 X - 0.4782, r = 0.9951. CONCLUSION: The preparation of OANO-1 microspheres was well. The release in vitro of OANO-1 microspheres showed significant sustained release.

Finite-size effect in the Eguíluz and Zimmermann model of herd formation and information transmission.

The Eguíluz and Zimmermann model of information transmission and herd formation in a financial market is studied analytically. Starting from a formal description on the rate of change of the system from one partition of agents in the system to another, a mean-field theory is systematically developed. The validity of the mean-field theory is carefully studied against fluctuations. When the number of agents N is sufficiently large and the probability of making a transaction a<<1/N ln N, finite-size effect is found to be significant. In this case, the system has a large probability of becoming a single cluster containing all the agents. For small clusters of agents, the cluster size distribution still obeys a power law but with a much reduced magnitude. The exponent is found to be modified to the value of -3 by the fluctuation effects from the value of -5/2 in the mean-field theory.

[The relationship between cellular infection by Hantaan virus and expression of beta3 integrin].

OBJECTIVE: To investigate the relationship between cellular entry of Hantaan virus (HTNV) and expression of beta3 integrin in beta3-integrin-deficient and HTNV-insusceptible China hamster ovary (CHO) cells. METHODS: Eukaryotic expression vector encoding human integrin beta3 and eukaryotic expression vector harboring human integrin alphav or alphaIIb subunit cDNA were transfected into HTNV non-permissive CHO cells individually or collectively. Screening for stable transfectant clones was performed using G418 selective (culture medium. The exogenous gene expression was analyzed qualitatively and quantitatively by immunofluorescence assay (IFA) and flow cytometry (FCM). Various modified CHO cells and untransfected CHO cells were infected using HTNV A9. At various time points after infection, HTNV antigens in infected cells were detected qualitatively and quantitatively by IFA, FCM. RESULTS: Highly-effective surface expression of beta3 integrin was measured in CHO/alphavbeta3 and CHO/alphaIIbbeta3, while weaker surface expression was detected in CHO/beta3 (P < 0.05). Expression of alphav or alphaIIb integrin in the individually transfected group was significantly lower than in the cotransfected group (P < 0.01) and the sites of localization changed. In contrast, effective surface expression was not seen when pcDNA3 was transfected alone. The infection rate of CHO/alphavbeta3 (60.1%) and CHO/alphaIIbbeta3 (55. 9%) cells were significantly higher than that of CHO/beta3 (38.7%) cells, while the infection rate of CHO/beta3 was significantly higher than that of CHO/alphav, CHO/pcDNA3 and CHO cells respectively. There was a close relationship between the positive percentage of HTNV A9-infected cells and expression of beta3 integrin. CONCLUSION: These results indicated that cellular entry of HTNV was related to the expression of beta3 integrin.

[Complete genome sequence of 84FLi, a Hantaan virus strain isolated from the liver of fetus aborted by a pregnant women with hemmorrhagic fever with renal syndrome].

OBJECTIVE: To study the complete genome sequence of the Chinese Hantaan virus vaccine strain 84FLi and learn about its molecular characters. METHODS: The virus strain 84FLi was isolated from the liver of a fetus aborted by pregnant women with hemorrhagic fever with renal syndrome. The cDNAs of L M and S segments were amplified fragment by fragment using RT-PCR. The purified PCR products were sequenced directly or cloned into pMD18-T vector and then sequenced. RESULTS: The complete genome of strain 84FLi was composed of L ( 6 533 bp) M (3 616 bp) and S (1 688 bp) coding 2151 1135 and 429 amino acids respectively. The entire sequence composition was 3830A 2050C 2510G and 3447T the GC and AT contents were 38.52% and 61.48%. Homology analysis showed that the homologies of 84 FLi S segment nucleotide sequences with strain RG9 (isolated in Guangzhou) and strain Chen4 (isolated in Anhui) were 99.6%. There were 83.7% 84.0% and 87.2% nucleotide sequences homology with the three segments of Hantaan virus foreign standard strain 76-118 while the amino acids sequences homology with those of 76-118 were 97.5% 96.0% and 97.9% respectively. CONCLUSION: The strain 84FLi is highly related to other Chinese Hantaan virus isolates and is in the same subtype with the other two Chinese isolates RG9 and Chen4.

Characterization of truncated hantavirus nucleocapsid proteins and their application for serotyping.

Hemorrhagic fever with renal syndrome (HFRS) is a fulminant infectious disease characterized by fever, hemorrhage, renal impairment, and thrombocytopenia. Hantaviruses associated with this belong to different serotypes: Hantaan (HTN), Seoul (SEO), Dobrava/Belgrade (DOB), and Puumala (PUU). The first two, HTN and SEO, are endemic in China. To investigate the epidemiology of HFRS and virus transmission in China, we constructed prokaryotic plasmids encoding truncated recombinant HTN and SEO nucleocapsid proteins (NPs), which lacked 154 amino acid (aa), 99 aa, or 49 aa in the N-terminal region, respectively. After expression, the truncated rNPs were tested as serotyping antigens, particularly for use in the enzyme-linked immunosorbent assay (ELISA). In addition, 68 acute and 52 convalescent sera were collected from HFRS patients from Harbin, Lantian, and Kaifeng regions in China in 2004, which had hantavirus specific antibodies by IFA. A neutralization test was used to differentiate these, which showed that 73 were due to HTN infection, 33 to SEO infection, and 14 undetermined. By ELISA, the truncated rNPs, that lacked 99 (rNP100) or 49 (rNP50) N-terminal amino acids of the NPs of HTN and SEO, were able to differentiate HTNV and SEOV-specific immune sera, but the rNP155 could not. Particularly, the ELISAs based on the rNP50s had a result comparable to PRNT. Thus, the rNP50 is recommended as efficient serotyping antigen for hantavirus infection diagnosis by ELISA.

[A preliminary genetic reassortment between Hantaan virus and Seoul virus strains].

OBJECTIVE: To determine the frequency and characteristics of reassortment among Hantaan and Seoul viruses causing hemorrhagic fever with renal syndrome (HFRS). METHODS: Mixed infections were initiated in tissue culture, using Hantaan virus strain 76 - 118 and Seoul virus strain SR-11. Potential reassortant virus plaques were picked out by multiplex RT-PCR, using primers specific for individual genome segments (L, M, S) of each strain. RESULTS: Most of the progeny virus plaques (68.19% of 44) had parental genotype of 76 - 118 strain or SR-11 strain while 2 of 44 plaques had mixed genotypes that yielded RT-PCR bands for the same segment of both parental strains. Reassortant viruses were detected in 68.19% of 44 progeny plaques tested, involving the M and S segments. In addition, approximately 4.55% of the progeny virus plaques appeared to contain S or M segments originating from both parental virus strains, showing that they were diploid. CONCLUSION: Genetic reassortment can occur between Hantaan virus and Seoul virus strains.

[Construction of human integrin beta3 subunit eukaryotic expression vector and efficient surface expression of integrin alphaIIbbeta3].

AIM: To establish efficient surface expression of Homo sapiens integrin alphaIIbbeta3 in beta3-integrin-deficient and HV-insusceptible CHO cells, so as to lay the foundation for the further study of cellular entry of hantavirus mediated by beta3 integrins. METHODS: Eukaryotic expression vector pcDNA3.1-beta3 harboring ORF region of human integrin beta3 subunit cDNA was constructed, then pcDNA3.1-beta3 and eukaryotic expression vector pBJ1-alphaIIb containing human integrin alphaIIb subunit cDNA were transfected into CHO cells alone or together. The expression of exogenous genes were analyzed by indirect immunofluorescence assay (IFA). RESULTS: The eukaryotic expression vector pcDNA3.1-beta3 was constructed successfully. IFA examination showed that surface expression of integrin alphaIIb beta3 was highly effective in cotransfection group, while surface expression was weak on CHO cells transfected with pcDNA3.1-beta3 alone,and no effective surface expression was found in pBJ1-alphaIIb-transfected group. CONCLUSION: Efficient surface expression of integrin alphaIIb beta3 requires expression of both subunits.