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Sample records for surface ag hbsag

  1. Breaking tolerance in hepatitis B surface antigen (HBsAg) transgenic mice by vaccination with cross-reactive, natural HBsAg variants

    DEFF Research Database (Denmark)

    Schirmbeck, Reinhold; Dikopoulos, Nektarios; Kwissa, Marcin

    2003-01-01

    Processing exogenous hepatitis B surface antigen (HBsAg) of the hepatitis B virus (HBV) generates the K(b)-binding S(208-215) epitope 1; processing endogenous HBsAg generates the K(b)-binding S(190-197) epitope 2. Cross-reactive CD8(+) T cell responses were primed to epitope 1 but not epitope 2...... HBs-tg mice showed reduced antigenemia. Hence, vaccination with natural HBsAg variants from different HBV sero/genotypes can prime cross-reactive, specific CD8(+) T cell immunity that breaks tolerance to HBsAg....

  2. Analysis of hepatitis B surface antigen (HBsAg) using high-sensitivity HBsAg assays in hepatitis B virus carriers in whom HBsAg seroclearance was confirmed by conventional assays.

    Science.gov (United States)

    Ozeki, Itaru; Nakajima, Tomoaki; Suii, Hirokazu; Tatsumi, Ryoji; Yamaguchi, Masakatsu; Kimura, Mutsuumi; Arakawa, Tomohiro; Kuwata, Yasuaki; Ohmura, Takumi; Hige, Shuhei; Karino, Yoshiyasu; Toyota, Joji

    2018-02-01

    We investigated the utility of high-sensitivity hepatitis B surface antigen (HBsAg) assays compared with conventional HBsAg assays. Using serum samples from 114 hepatitis B virus (HBV) carriers in whom HBsAg seroclearance was confirmed by conventional HBsAg assays (cut-off value, 0.05 IU/mL), the amount of HBsAg was re-examined by high-sensitivity HBsAg assays (cut-off value, 0.005 IU/mL). Cases negative for HBsAg in both assays were defined as consistent cases, and cases positive for HBsAg in the high-sensitivity HBsAg assay only were defined as discrepant cases. There were 55 (48.2%) discrepant cases, and the range of HBsAg titers determined by high-sensitivity HBsAg assays was 0.005-0.056 IU/mL. Multivariate analysis showed that the presence of nucleos(t)ide analog therapy, liver cirrhosis, and negative anti-HBs contributed to the discrepancies between the two assays. Cumulative anti-HBs positivity rates among discrepant cases were 12.7%, 17.2%, 38.8%, and 43.9% at baseline, 1 year, 3 years, and 5 years, respectively, whereas the corresponding rates among consistent cases were 50.8%, 56.0%, 61.7%, and 68.0%, respectively. Hepatitis B virus DNA negativity rates were 56.4% and 81.4% at baseline, 51.3% and 83.3% at 1 year, and 36.8% and 95.7% at 3 years, among discrepant and consistent cases, respectively. Hepatitis B surface antigen reversion was observed only in discrepant cases. Re-examination by high-sensitivity HBsAg assays revealed that HBsAg was positive in approximately 50% of cases. Cumulative anti-HBs seroconversion rates and HBV-DNA seroclearance rates were lower in these cases, suggesting a population at risk for HBsAg reversion. © 2017 The Japan Society of Hepatology.

  3. Prevalence of Hepatitis-B Surface Antigen (HbsAg), Hepatitis C ...

    African Journals Online (AJOL)

    The prevalence of Hepatitis-B surface antigen (HBsAg), Hepatitis C virus (HCV) and Human immunodeficiency virus (HIV) was determined among apparently healthy male blood donors in Aminu Kano Teaching Hospital, Kano, between January and December, 2002. A total of 2,288 blood samples from the blood donors ...

  4. Sero-prevalence of Hepatitis B Surface Antigen (HBsAg), in Sexually ...

    African Journals Online (AJOL)

    Sero-prevalence of Hepatitis B Surface Antigen (HBsAg), in Sexually Transmitted Disease Patients. ... partners in the past 6 months, a history of a number of episodes of STDs, history of heterosexual exposure to partners at risk, for example prostitutes; a history of symptoms of an STD at the commencement of the study.

  5. Comparative study of methods of detection of hepatitis ′B′ surface antigen (HBsAg.

    Directory of Open Access Journals (Sweden)

    Parab V

    1989-04-01

    Full Text Available The serum samples were collected from 52 patients of acute viral hepatitis and 235 hospital staff from Kasturba Hospital for Infectious Diseases. HBsAg was detected in their sera by counter-immuno-electrophoresis (CIEP, reverse passive hemogglutination (RPHA and by micro-enzyme-linked-immunosorbent assay (ELISA technique. Among the patients, HBsAg was detected in 12 cases (23% by CIEP, in 18 cases (34% by RPHA and in 23 patients (45% by ELISA. In the hospital staff, HBsAg was detected in 4 samples (1.7% by CIEP, in 8 samples (3.5% by RPHA and in 32 samples (13.5% by ELISA. Thus ELISA was found to be the most sensitive technique in detecting HBsAg.

  6. Clinical Characteristics and Correlation Analysis of Subjects with Chronic Hepatitis B Virus (HBV) Infection and Sustained Low Levels of Hepatitis B Surface Antigen (HBsAg)

    Science.gov (United States)

    Cheng, Jun; Dai, Yuzhu; Yan, Li; Zhou, Huajun; Xu, Xujian

    2018-01-01

    Background The aim of this study was to investigate the clinical characteristics of individuals with chronic hepatitis B virus (HBV) infection with persistent low levels of hepatitis B surface antigen (HBsAg) and to undertake a correlation analysis of the clinical characteristics. Material/Methods The study included 1,204 subjects with chronic HBV infection. Serum HBsAg, HBV envelope antigen (HBeAg), and HBV core antigen (HBcAg) levels were measured using the chemiluminescent microparticle immunoassay (CMIA) and the neutralization test. HBV DNA was measured using real-time fluorescence quantitative polymerase chain reaction (RT-FQ-PCR). Results There were 1,023 subjects in the high-level HBsAg group (HBsAg level ≥10 IU/mL) and 181 subjects in the low-level HBsAg group (HBsAg level HBV-M2), and the asymptomatic carrier (ASC) status was 98.34%. The low-level HBsAg group had a lower HBV DNA-positive rate compared with the high-level HBsAg group (40.33% vs. 75.07%), with a normal distribution across all age groups (P>0.05). The low-level HBsAg group included an older age group. A low-level of HBsAg was positively correlated with a low level of replication of HBV DNA (r=0.452). Conclusions The findings of this study showed that individuals with chronic HBV infection and sustained low-levels of HBsAg were an older population and had a lower level of replicating HBV DNA when compared with individuals with high levels of HBsAg, and the majority (93.7%) were also HBsAg and HBeAg and HBcAg-positive. PMID:29593208

  7. A vaccine prepared from the 22 nm particles of surface hepatitis B antigen (HBsAg)

    International Nuclear Information System (INIS)

    Karelin, V.P.; Babaeva, E.E.; Gubenko, E.F.; Kaulen, D.K.; Zhdanov, V.M.

    1980-01-01

    A method for obtaining a subunit inactivated vaccine preparation from the 22-nm particles of HBsAg is proposed. For inactivation of the residual infectious hepatitis B virus (HBV) the preparations were successively treated with 1% sodium dodecyl sulfate (SDS) and nucleases. In addition, thermal denaturation and ultraviolet irradiation of HBV DNA were used. As a control the biologic activity of a reference virus (SV40) was tested after the same treatment. The effectiveness of DNA inactivation was monitored by adding 3H-thymidine labeled reference virus to the vaccine preparations. The purified and inactivated HBsAg was adsorbed on Al2O3. Antigenicity was calculated on the basis of the determination of antibody in guinea pigs immunized with various doses of the vaccine, and the release of 125 I- HBsAg from blood and kidneys in immunized and control mice was analyzed. Possible methods of inactivation and control of HBV vaccine is discussed

  8. Expression of hepatitis B surface antigen (HBsAg) gene in ...

    African Journals Online (AJOL)

    The transformed nature of the plants was confirmed by polymerase chain reaction (PCR) analysis and Southern blot hybridization. Expression of HBsAg was confirmed by western blotting and levels of expression were assayed by enzyme-linked immunosorbent assay (ELISA). Southern blot hybridization confirmed the ...

  9. Expression of Hepatitis B virus surface antigen (HBsAg from genotypes A, D and F and influence of amino acid variations related or not to genotypes on HBsAg detection

    Directory of Open Access Journals (Sweden)

    Natalia M. Araujo

    Full Text Available The impact of hepatitis B virus (HBV genotypes on the sensitivity of surface antigen (HBsAg detection assays has been poorly investigated. Here, plasmids carrying consensus or variant coding sequences for HBV surface proteins from genotypes A, D and F, were constructed. HBsAg levels were evaluated in medium and extracts of transfected CHO cells by a commercial polyclonal-based assay. We show that HBsAg detection values of consensus forms from genotypes D and F were, respectively, 37% and 30% lower than those obtained by genotype A. However, the presence of two single variations, T143M in genotype A, and T125M in genotype D, produced a decrease of 44% and an increase of 34%, respectively, on HBsAg mean values in comparison with their consensus forms. In conclusion, HBsAg detection levels varied among HBV genotypes. However, unique amino acid substitutions not linked to genotypes, such as T125M and T143M described here, should have more implications in HBV immunological diagnostics than the set of variations characteristic of each HBV genotype.

  10. [Clinical evaluation of a novel HBsAg quantitative assay].

    Science.gov (United States)

    Takagi, Kazumi; Tanaka, Yasuhito; Naganuma, Hatsue; Hiramatsu, Kumiko; Iida, Takayasu; Takasaka, Yoshimitsu; Mizokami, Masashi

    2007-07-01

    The clinical implication of the hepatitis B surface antigen (HBsAg) concentrations in HBV-infected individuals remains unclear. The aim of this study was to evaluate a novel fully automated Chemiluminescence Enzyme Immunoassay (Sysmex HBsAg quantitative assay) by comparative measurements of the reference serum samples versus two independent commercial assays (Lumipulse f or Architect HBsAg QT). Furthermore, clinical usefulness was assessed for monitoring of the serum HBsAg levels during antiviral therapy. A dilution test using 5 reference-serum samples showed linear correlation curve in range from 0.03 to 2,360 IU/ml. The HBsAg was measured in total of 400 serum samples and 99.8% had consistent results between Sysmex and Lumipulse f. Additionally, a positive linear correlation was observed between Sysmex and Architect. To compare the Architect and Sysmex, both methods were applied to quantify the HBsAg in serum samples with different HBV genotypes/subgenotypes, as well as in serum contained HBV vaccine escape mutants (126S, 145R). Correlation between the methods was observed in results for escape mutants and common genotypes (A, B, C) in Japan. Observed during lamivudine therapy, an increase in HBsAg and HBV DNA concentrations preceded the aminotransferase (ALT) elevation associated with drug-resistant HBV variant emergence (breakthrough hepatitis). In conclusion, reliability of the Sysmex HBsAg quantitative assay was confirmed for all HBV genetic variants common in Japan. Monitoring of serum HBsAg concentrations in addition to HBV DNA quantification, is helpful in evaluation of the response to lamivudine treatment and diagnosis of the breakthrough hepatitis.

  11. Prevalence of hepatitis B virus surface antigen (HBsAg) in patients undergoing extraction at the University College Hospital, Ibadan.

    Science.gov (United States)

    Odaibo, G N; Arotiba, J T; Fasola, A O; Obiechina, A E; Olaleye, O D; Ajagbe, H A

    2003-09-01

    Hepatitis B Virus (HBV) infection and its sequelae (liver chirrhosis and hepatic carcinoma) are endemic in Africa. The risk of transmission of the infection during dental treatment is real. This study was carried out to determine the rate of Hepatits B Surface Antigen (HBsAg) as a marker of hepatitis B virus infection in patients undergoing dental extraction in order to highlight the potential risk of nosocomial transmission among the Dental Health Workers (DHW) and their patients. Three hundred (143 males and 157 females) consecutive patients requiring dental extraction who volunteered were enrolled into this study. Their ages ranged from 11 years to 95 years with a mean of 37.2 years (SD = 16.725) and a median of 36 years. The overall HBsAg infection rate was 18.3% (55/300). A higher infection rate (23.1%) occurred among the male patients compared with 14% in females (p = 0.0086). The high rate of HBV infection found among this study population suggests that Dental Surgeons in this environment have a high risk of exposure to hepatitis B virus and should be immunized at the beginning of their professional life. Universal biosafety measures should be observed strictly in all invasive procedures.

  12. Application of a newly developed high-sensitivity HBsAg chemiluminescent enzyme immunoassay for hepatitis B patients with HBsAg seroclearance.

    Science.gov (United States)

    Shinkai, Noboru; Matsuura, Kentaro; Sugauchi, Fuminaka; Watanabe, Tsunamasa; Murakami, Shuko; Iio, Etsuko; Ogawa, Shintaro; Nojiri, Shunsuke; Joh, Takashi; Tanaka, Yasuhito

    2013-11-01

    We modified and automated a highly sensitive chemiluminescent enzyme immunoassay (CLEIA) for surface antigen (HBsAg) detection using a combination of monoclonal antibodies, each for a specific epitope of HBsAg, and by improving an earlier conjugation technique. Of 471 hepatitis B virus (HBV) carriers seen in our hospital between 2009 and 2012, 26 were HBsAg seronegative as determined by the Abbott Architect assay. The Lumipulse HBsAg-HQ assay was used to recheck those 26 patients who demonstrated seroclearance by the Abbott Architect assay. The performance of the Lumipulse HBsAg-HQ assay was compared with that of a quantitative HBsAg detection system (Abbott Architect) and the Roche Cobas TaqMan HBV DNA assay (CTM) (lower limit of detection, 2.1 log copies/ml) using blood serum samples from patients who were determined to be HBsAg seronegative by the Abbott Architect assay. Ten patients had spontaneous HBsAg loss. Of 8 patients treated with nucleotide analogues (NAs), two were HBsAg seronegative after stopping lamivudine therapy and 6 were HBsAg seronegative during entecavir therapy. Eight acute hepatitis B (AH) patients became HBsAg seronegative. Of the 26 patients, 16 were HBsAg positive by the Lumipulse HBsAg-HQ assay but negative by the Abbott Architect assay. The differences between the two assays in terms of detectable HBsAg persisted over the long term in the spontaneous loss group (median, 10 months), the NA-treated group (2.5 months), and the AH group (0.5 months). In 9 patients, the Lumipulse HBsAg-HQ assay detected HBsAg when HBV DNA was negative by the CTM assay. HBsAg was also detected by the Lumipulse HBsAg-HQ assay in 4 patients with an anti-HBs concentration of >10 mIU/ml, 3 of whom had no HBsAg escape mutations. The automatic, highly sensitive HBsAg CLEIA Lumipulse HBsAg-HQ is a convenient and precise assay for HBV monitoring.

  13. Impact of "a" determinant mutations on detection of hepatitis B surface antigen (HBsAg) in HBV strains from Chinese patients with occult hepatitis B.

    Science.gov (United States)

    Huang, Xiangyan; Ma, Chenyun; Zhang, Qiang; Shi, Qingfen; Huang, Tao; Liu, Chao; Li, Jie; Hollinger, F Blaine

    2017-10-01

    This study was designed to detect mutations that occur within the "a" determinant in the S gene of the hepatitis B virus (HBV) in patients with occult hepatitis B (OHB), and to analyze the influence of these mutations on expression and reactivity of the hepatitis B surface antigen (HBsAg). Twenty-three certified OHB samples were compared to 32 HBsAg positive samples from patients with chronic hepatitis B. The median HBV DNA levels in the OHB group were significantly lower than those in the control group (P determinant were analyzed by gene amplification and sequencing. This revealed mixed infections in which clones within a sample displayed either different mutations or mutations in association with clones that exhibited wild type amino acid patterns. Sequencing analysis also showed a significant difference between the proportions of amino acid mutations observed in the OHB and control groups. Seven recombinant S (rS) proteins with corresponding OHB mutations and three wild type alleles were expressed and purified in the Pichia pastoris expression system to preserve conformational attributes, and their reactivity analyzed using six commercial HBsAg assays. The OHB sera were HBsAg nonreactive while the rS proteins with corresponding OHB mutations were universally reactive. Thus, we postulate that the reduced binding affinity between mutated HBsAg and its antibody may not be as important in defining OHB as is the effect of specific mutations in the preS/S region of the genome that affect the synthesis and secretion of the S protein and/or the virion. © 2017 Wiley Periodicals, Inc.

  14. Prevalence of Hepatitis B Surface Antigen (HBsAg) Amongst Alcohol ...

    African Journals Online (AJOL)

    The prevalence of Hepatitis B surface Antigen was studied amongst alcohol consumers and non– consumers (Control subjects) in Bassa Local Government Area (LGA) of Plateau State. Three hundred and five (305) subjects comprising 255(83.61%) alcoholics and 50(16.39%) non-alcoholic control subjects were screened ...

  15. Heteroassembled gold nanoparticles with sandwich-immunoassay LSPR chip format for rapid and sensitive detection of hepatitis B virus surface antigen (HBsAg).

    Science.gov (United States)

    Kim, Jinwoon; Oh, Seo Yeong; Shukla, Shruti; Hong, Seok Bok; Heo, Nam Su; Bajpai, Vivek K; Chun, Hyang Sook; Jo, Cheon-Ho; Choi, Bong Gill; Huh, Yun Suk; Han, Young-Kyu

    2018-06-01

    This study aimed to develop a more sensitive method for the detection of hepatitis B surface antigen (HBsAg) using heteroassembled gold nanoparticles (AuNPs). A single layered localized surface plasmon resonance (LSPR) chip format was developed with antigen-antibody reaction-based detection symmetry using AuNPs, which detected HBsAg at 10 pg/mL. To further improve the detection limit, a modified detection format was fabricated by fixing a secondary antibody (to form a heteroassembled sandwich format) to the AuNP monolayer, which enhanced the detection sensitivity by about 100 times. The developed heteroassembled AuNPs sandwich-immunoassay LSPR chip format was able to detect as little as 100 fg/mL of HBsAg within 10-15 min. In addition, the heteroassembled AuNPs sandwich-immunoassay LSPR chip format did not show any non-specific binding to other tested antigens, including alpha fetoprotein (AFP), C-reactive protein (CRP), and prostate-specific antigen (PSA). These findings confirm that the proposed detection strategy of heteroassembled AuNPs sandwich-immunoassay LSPR chip format may provide a new platform for early diagnosis of various human diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Comparison of serum HBsAg quantitation by four immunoassays, and relationships of HBsAg level with HBV replication and HBV genotypes.

    Directory of Open Access Journals (Sweden)

    Edouard Tuaillon

    Full Text Available BACKGROUND: The decline in hepatitis B virus surface antigen (HBsAg may be an early predictor of the viral efficacy of Hepatitis B virus (HBV therapy. The HBsAg levels obtained by different immunoassays now need comparing and the relationships between levels of HBsAg and HBV DNA alongside HBsAg and genotype must be evaluated. METHODOLOGY/PRINCIPAL FINDINGS: HBsAg levels were compared among 80 patients using the Abbott Architect assay, a commercial immunoassay approved for HBsAg detection and quantitation, and three other assays derived from immunoassays approved for HBsAg detection (manufactured by Diasorin, Bio-Rad and Roche. Good correlation was found between the Abbot vs. Diasorin, Bio-Rad and Roche assays with narrow 95% limits of agreement and small mean differences: -0.06 to 0.11, -0.09 log(10 IU/mL; -0.57 to 0.64, -0.04 log(10 IU/mL; -0.09 to 0.45, -0.27 log(10 IU/mL, respectively. These agreements were not affected by genotypes A or D. HBsAg was weakly correlated with HBV DNA, whatever the HBsAg assay used: Abbott, ρ = 0.36 p = 0.001, Diasorin ρ = 0.34, p = 0.002; Bio-Rad ρ = 0.37, p<0.001; or Roche ρ = 0.41, p<0.001. This relationship between levels of HBsAg and HBV DNA seemed to depend on genotypes. Whereas HBsAg (Abbott assay tended to correlate with HBV DNA for genotype A (ρ = 0.44, p = 0.02, no such correlation was significant for genotypes D (ρ = 0.29, p = 0.15. CONCLUSION/SIGNIFICANCE: The quantitation of HBsAg in routine clinical samples is comparable between the reference assay and the adapted assays with acceptable accuracy limits, low levels of variability and minimum discrepancy. While HBsAg quantitation is not affected by HBV genotype, the observed association between levels of HBsAg and HBV DNA seems genotype dependent.

  17. Application of a Newly Developed High-Sensitivity HBsAg Chemiluminescent Enzyme Immunoassay for Hepatitis B Patients with HBsAg Seroclearance

    OpenAIRE

    Shinkai, Noboru; Matsuura, Kentaro; Sugauchi, Fuminaka; Watanabe, Tsunamasa; Murakami, Shuko; Iio, Etsuko; Ogawa, Shintaro; Nojiri, Shunsuke; Joh, Takashi; Tanaka, Yasuhito

    2013-01-01

    We modified and automated a highly sensitive chemiluminescent enzyme immunoassay (CLEIA) for surface antigen (HBsAg) detection using a combination of monoclonal antibodies, each for a specific epitope of HBsAg, and by improving an earlier conjugation technique. Of 471 hepatitis B virus (HBV) carriers seen in our hospital between 2009 and 2012, 26 were HBsAg seronegative as determined by the Abbott Architect assay. The Lumipulse HBsAg-HQ assay was used to recheck those 26 patients who demonstr...

  18. No response to hepatitis B vaccine in infants born to HBsAg(+) mothers is associated to the transplacental transfer of HBsAg.

    Science.gov (United States)

    Wang, Jing; He, Yingli; Jin, Dongfang; Liu, Jinfeng; Zheng, Jie; Yuan, Ningxia; Bai, Yun; Yan, Taotao; Yang, Yuan; Liu, Yong; Zhang, Shulin; Zhao, Yingren; Chen, Tianyan

    2017-08-01

    No or low hepatitis B (HB) vaccine response is more frequent in infants from HBsAg(+) mothers than those from HBsAg(-). Our previous study found temporary positivity of HBsAg in infants from HBsAg(+) mothers. In this study, we hypothesized that HBsAg in infant blunt immune response to standard hepatitis B vaccination. A total of 328 consecutive HBsAg(+) mothers and their offspring were enrolled. Blood samples were taken from mothers and their infants and quantified for HBsAg, anti-HBs titer and HBV DNA load concentration; Placenta samples were collected to stain for HBsAg. First, 6.7% infants (22/328) showed anti-HBs titer lower than 10 mIU/mL after HB vaccination (non-response to HB vaccine). HBsAg(+) newborns showed higher risk of non-response than HBsAg(-) infants (13.0% versus 5.0%, p = 0.016). Infants from high HBsAg titer mothers displayed higher risk of HBsAg positivity at birth than those from low titer mothers (45.3% versus 2.8%, p < 0.001). HBsAg titer in mothers of HBsAg(+) newborns was much higher than mothers of HBsAg(-) newborns (p < 0.001). All those data supported HBsAg can be transferred through placenta. Our hypothesis was further reinforced by immunostaining with specific antibody against HBsAg, a substantial higher prevalence (87.5% versus 30.8%, p = 0.024) and stronger immunostaining (p = 0.008) was demonstrated in HBsAg(+) group comparing with placenta of the HBsAg(-) group. No response to HB vaccine in infants of HBsAg(+) mothers was associated to the transplacental transfer of HBsAg.

  19. Predictive role of serum HBsAg and HBcrAg kinetics in patients with HBeAg-negative chronic hepatitis B receiving pegylated interferon-based therapy.

    Science.gov (United States)

    Chuaypen, N; Posuwan, N; Chittmittraprap, S; Hirankarn, N; Treeprasertsuk, S; Tanaka, Y; Shinkai, N; Poovorawan, Y; Tangkijvanich, P

    2018-03-01

    To investigate the role of serum hepatitis B core-related antigen (HBcrAg) kinetics in predicting long-term outcome of pegylated interferon (PEG-IFN)-based therapy in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). A total of 121 Thai patients with HBeAg-negative CHB recruited from a previous randomized trial of 48-week PEG-IFN alone or combined with entecavir were enrolled. Hepatitis B surface antigen (HBsAg) and HBcrAg levels were serially examined. Paired biopsy samples taken at baseline and after treatment were assessed for intrahepatic covalently closed circular DNA (cccDNA). Persistent virologic remission (PVR, defined by persistent hepatitis B virus (HBV) DNA <2000 IU/mL) and HBsAg clearance at 3 years after treatment were 29% (35/121) and 9% (11/121) respectively. Baseline HBcrAg correlated with HBV DNA and cccDNA but not with HBsAg. Baseline HBsAg, as well as HBsAg and HBcrAg, declines were associated with PVR, while HBsAg decline was predictive of HBsAg clearance. High baseline antigen levels (HBsAg ≥3.4 log 10 IU/mL plus HBcrAg ≥3.7 log 10 U/mL) yielded high negative predictive values of PVR (45/50, 90%) and HBsAg clearance (50/50, 100%). At week 12, declines of HBsAg, HBcrAg and both antigens combined of <0.5 log 10 yielded negative predictive values for PVR of 90% (71/79), 82% (61/74) and 96% (48/50) respectively. Quantitative HBcrAg was significantly associated with cccDNA in HBeAg-negative CHB. This novel antigen, together with HBsAg, could identify patients with low probability of PVR and HBsAg clearance in long-term follow-up. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  20. The Study on the Prevalence and Significance of Urinary HBsAg Detection

    International Nuclear Information System (INIS)

    Han, Jin Suk; Pyo, Heui Jung; Shin, Young Tae; Park, Jeong Sik; Kim, Suhng Gwon; Choe, Kang Won; Lee, Jung Sang; Lee, Mon Ho

    1981-01-01

    HBsAg. was identified in the urine of the patients positive for serum HBsAg. by Tripatzis in 1970. In 1977, Hourani et al reported the incidence of HBsAg. in urine was about 52% in the patients positive for serum HBsAg. with hemodialysis treatment due to chronic renal failure. A series of studies on the HBsAg. in urine has revealed the urine of the patients positive for serum HBsAg. to be important source of infection. But there's much room to debate on the relationship of HBsAg. in urine with infectivity and the exact mechanism of urinary emergence of HBsAg. The authors detected HBsAg. in serum and urine by employing sandwitch solid-phase radioimmunoassay, and performed urinalysis, liver function test and renal function evaluation. Percutanous liver and/or kidney biopsies were done. Among 38 renal disease patients, 9 cases(23.4%) were shown to be positive for serum HBsAg. and 5 cases(55.5%) among above 9 patients positive for urine HBsAg. 56 cases(67.4%) of 83 liver disease patients revealed positive for serum HBsAg. All 10 renal and liver disease patients revealed positive serum HBsAg., and among the 9 cases(90%) positive for urine HBsAg. In the 25 patients positive for urine HBsAg. all of 5 renal patients and 9 renal and liver patients had hematuria or/and proteinuria above 2 positive for albumin. But in the 11 liver patients 6 cases(55.1%) were normal findings. And there's no significant in cpm of urine HBsAg. between the patient positive for serum HBsAg. and negative, and in cpm of serum HBsAg. between liver and renal disease patients. But there's statistical significance in cm of urine HBsAg. between renal and liver diseases.

  1. Prevalence of hepatitis b virus surface antigens (HBsag) and ...

    African Journals Online (AJOL)

    The prevalences of hepatitis B virus surface antigen (HBsAg) and hepatitis C virus (HCV) antibodies were determined in 560 blood donors sera using ELISA kits (DIALAB., Austria). Forty eight (8.57%) of these were positive for hepatitis B virus infection, while 33(5.89%) were positive to hepatitis C virus antibodies. The sex ...

  2. Species specificity for HBsAg binding protein endonexin II

    NARCIS (Netherlands)

    deBruin, WCC; Leenders, WPJ; Moshage, H; vanHaelst, UJGM

    Background/Aims: Hepatitis B virus displays a distinct species and tissue tropism, Previously we have demonstrated that a human liver plasma membrane protein,vith a molecular weight of approximately 34 kiloDalton specifically binds to HBsAg. This protein was identified as endonexin II, a Ca2+

  3. Prevalence of HBsAg, knowledge, and vaccination practice against ...

    African Journals Online (AJOL)

    Among the respondents, 56.7% had good knowledge and 94.8% reported poor practice of vaccination against viral hepatitis B infection. Mean knowledge and vaccination practices scores (%) were 72.54+7.60 and 29.44+14.37 respectively. Only 29% of the respondents did post vaccination testing for anti HBsAg.

  4. Quantification of HBsAg to predict low levels and seroclearance in HBeAg-negative patients receiving nucleos(tide analogues.

    Directory of Open Access Journals (Sweden)

    Teresa Broquetas

    Full Text Available HBeAg-negative chronic hepatitis B patients require long-term nucleos(tide analogues(NAs because loss of surface antigen (HBsAg is unusual. Low quantitative HBsAg (qHBsAg levels can identify patients with higher probability of seroclearance. The aim of our study was to evaluate qHBsAg in HBeAg-negative patients receiving NAs to predict a reduction of HBsAg levels and seroclearance.Retrospective analysis of qHBsAg in HBeAg-negative patients before and at years 1, 3, 5, 8 and over of NAs treatment.From 1999 to 2015, HBsAg was quantified in 358 serum samples from 95 HBeAg-negative patients. Low qHBsAg (0.3 log IU/mL showing a positive and negative predictive value of 42% and 100% to identify patients achieving low levels of HBsAg.Reduction of qHBsAg is slow in HBeAg-negative patients receiving NAs, although low levels or faster qHBsAg decline may occur in 14%. A qHBsAg reduction >0.3 log IU/mL at year 3 can identify patients with a higher probability of achieving low levels and HBsAg seroclearance.

  5. [Comparative study between HBsAg positive and HBsAg negative panarteritis nodosa in a series of 25 cases (author's transl)].

    Science.gov (United States)

    Iturralde, J F; Miranda, C F; Barbado, J; Peña, J; Seoane, J; Gil, A; Arnalich, F; Vázquez, J J

    1980-06-25

    Clinical symptoms, biochemical analyses, immunologic status and angiographic findings corresponding to seven HBsAg positive patients with panarteritis nodosa and to 16 HBsAg negative patients with panarteritis nodosa have been compared. HBsAg positive cases showed a statistical significant higher incidences of Raynaud's phenomenon (p less than 0.05) and cardiopathies (p les than 0.05), as well as high occurrence of blood hypertension, artropathy, liver involvement and peripheral neuropathy. Significant differences in relation to cell immunity were not found. Humoral immune disturbances were more common among HBsAg positive patients, being hypergammaglobulinemia (p less than 0.01), IgM increase and decrease of complement factors (C3, C4 and C3PA) the most frequent abnormalities recorded. Angiographic studies revealed a high incidence of microaneurisms for the HBsAg positive group.

  6. Reactivation of hepatitis B virus infection with persistently negative HBsAg on three HBsAg assays in a lymphoma patient undergoing chemotherapy.

    Science.gov (United States)

    Cheung, Wing-I; Chan, Henry Lik-Yuen; Leung, Vincent King-Sun; Tse, Chi-Hang; Fung, Kitty; Lin, Shek-Ying; Wong, Ann; Wong, Vincent Wai-Sun; Chau, Tai-Nin

    2010-02-01

    In patients with occult hepatitis B virus (HBV) infection, acute exacerbation may occur when they become immunocompromised. Usually, these patients develop hepatitis B surface antigen (HBsAg) seroreversion during the flare. Here we report on a patient with occult HBV infection, who developed HBV exacerbation after chemotherapy for diffuse large B-cell lymphoma. The resurgence of HBV DNA preceded the elevation of liver enzymes for 20 weeks. Atypically, despite high viraemia, serological tests showed persistently negative HBsAg using three different sensitive HBsAg assays (i.e., Architect, Murex and AxSYM). On comparing the amino acid sequence of the index patient with the consensus sequence, five mutations were found at pre-S1, five at pre-S2 and twenty-three mutations at the S region. Six amino acid mutations were located in the 'a' determinant, including P120T, K122R, M133T, F134L, D144A and G145A. The mutants K122R, F134L and G145A in our patient have not been tested for their sensitivity to Architect and Murex assays by the previous investigators and might represent the escape mutants to these assays.

  7. Evolution of full-length genomes of HBV quasispecies in sera of patients with a coexistence of HBsAg and anti-HBs antibodies.

    Science.gov (United States)

    Zhou, Tai-Cheng; Li, Xiao; Li, Long; Li, Xiao-Fei; Zhang, Liang; Wei, Jia

    2017-04-06

    Although the evolutionary changes of viral quasispecies are correlated to the pathological status of a disease, little is known in the coexistence of hepatitis B surface antigen (HBsAg) and antibodies to these antigens (anti-HBs). To examine evolutionary changes in hepatitis B virus (HBV) and their relationship to the coexistence of HBsAg and anti-HBs antibodies, HBV genomes in patients with a coexistence of HBsAg and anti-HBs antibodies (experimental group) and HBsAg positive without anti-HBs (control group) were assessed. Our results showed that quasispecies diversity was significantly higher in the experimental group for large HBsAg (LHBsAg), middle HBsAg (MHBsAg), and HBsAg genes. LHBsAg harbored dN/dS values eight times higher in the experimental group; however, the mean dN/dS ratios in genes HbxAg, Pol and PreC/C of the experimental patients had an opposite trend. Phylogenetic trees in the experimental group were more complex than the control group. More positive selection sites, mutations and deletions were observed in the experimental group in specific regions. Furthermore, several amino acid variants in epitopes were potentially associated with the immune evasion. In conclusion, cumulative evolutionary changes in HBV genome that facilitate immune evasion provide insights into the genetic mechanism of a coexistence of HBsAg and anti-HBs antibodies.

  8. Spontaneous HBsAg loss in Korean patients: relevance of viral genotypes, S gene mutations, and covalently closed circular DNA copy numbers

    Directory of Open Access Journals (Sweden)

    Kyun-Hwan Kim

    2014-09-01

    Full Text Available Background/AimsOccult HBV infection can persist following HBsAg loss and be transmitted, but the virological features are not well defined.MethodsHere we investigated 25 Korean patients who lost HBsAg during follow up, either spontaneously or subsequent to therapy.ResultsWhereas subtype adr (genotype C was found in 96% of HBsAg positive patients, 75 % of patients who lost HBsAg spontaneously were seemed to be infected with the ayw subtype with sequence similar to genotype D. Mutations in the major hydrophilic region (MHR of HBsAg were found in 7 patients who lost HBsAg spontaneously. The mutations include T123S, M125I/N, C139R, D144E, V177A, L192F, and W196L, some of which have not been reported before. Functional analysis via transfection experiments indicate that the C139R and D144E mutations drastically reduced HBsAg antigenicity, while the Y225del mutation found in one interferon-treated patient impaired HBsAg secretion.ConclusionsLack of detectable HBsAg in patient serum could be explained by low level of ccc DNA in liver tissue, low antigenicity of the surface protein, or its secretion defect.

  9. Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg

    OpenAIRE

    Marcondes,Jackson; Hansen,Ekkehard

    2008-01-01

    The obtainment of transgenic edible plants carrying recombinant antigens is a desired issue in search for economic alternatives viewing vaccine production. Here we report a strategy for genetic transformation of lettuce plants (Lactuca sativa L.) using the surface antigen HBsAg of hepatitis B virus. Transgenic lettuce seedlings were obtained through the application of a regulated balance of plant growth regulators. Genetic transformation process was acquired by cocultivation of cotyledons wit...

  10. Serological profile of incidentally detected asymptomatic HBsAg positive subjects (IDAHS)

    International Nuclear Information System (INIS)

    Khokhar, N.; Gill, M.L.

    2004-01-01

    Objective: To evaluate the serological profile of patients with incidentally detected positive hepatitis-B surface antigen (HBsAg) and to asses the risk factors. Design: An observational study. Place and Duration of Study: This study was conducted at Shifa International Hospital, Islamabad from 1999 to 2003. Patients and Methods: All patients who presented to gastroenterology clinic of Shifa Intentional Hospital, Islamabad with positive HBsAg, detected incidentally, were tested for alamine transaminase (ALT), hepatitis Beantigen (HBeAg) and in certain cases hepatitis-B virus DNA (HBV DNA) by polymerase chain reaction (PCR). Their risk factors for acquisition of infection were assessed with specific questions. Results: A total of 224 patients were examined. One hundred sixty-four (73.2%) were male and 60 (26.8%) female. Mean age of all the subjects was 32.45 plus minus 11.85 years. Out of 224 patients, 48 (21.4%) were positive for HBeAg and 176 (78.6%) were negative. Out of 48 subjects who were positive for HBeAg, 36 underwent HBV DNA determination and 32 (88.8%) were positive for HBV DNA. Out of 176 subjects who had negative HBeAg, 46 had elevated ALT and in those HBV DNA was performed and 14 had positive HBV DNA. Most common risk factors detected in these patients were intramuscular injections and surgery, however, in a large number, risk factors were unknown. Conclusion: Twenty-one percent asymptomatic subjects with positive HBsAg were found to be HBeAg positive. A large number of subjects with negative HBeAg had HBV DNA positive suggesting presence of precore mutants. Intramuscular injections and surgery were noted to be frequent risk factors in these subjects. (author)

  11. Low occurrence of HBsAg but high frequency of transient occult HBV infection in vaccinated and HBIG-administered infants born to HBsAg positive mothers.

    Science.gov (United States)

    Zhou, Shan; Li, Tingting; Allain, Jean-Pierre; Zhou, Bin; Zhang, Yuming; Zhong, Mei; Fu, Yongshui; Li, Chengyao

    2017-12-01

    The status of chronic and occult HBV infection (OBI) in neonatal hepatitis B vaccine and immunoglobulin (HBIG) vaccinated infants born to HBsAg+ mothers was investigated at a major hospital in China. Seventy-seven and 15 blood samples were collected in first or second follow-up detection from the vaccinated babies aged 3-36 months born to 43 HBsAg+ or plus 25 HBeAg+ mothers. HBV infection was analyzed between the paired baby and mother by serology and DNA analysis. Among 77 children born to 68 HBsAg+ mothers, 3.9% (3/77) were HBsAg+, and 36.4% (28/77) were HBV DNA+/HBsAg- (OBIs) by a single PCR, respectively. Thirteen of 28 HBV DNA+/HBsAg- samples were conformed by two PCRs or S sequence, which accounted for 16.9% (13/77) of children. Three HBsAg+ and six OBIs were genotyped in consistent with their mother's HBV strains. Of 77 babies' blood samples, anti-HBs reactivity varied slightly according to age groups, while passively transmitted anti-HBc reactivity declined from 100% high reactivity at age 3-5 months to mostly negative at age ≥12 months. Babies with apparent OBI had higher levels of anti-HBc and lower levels of anti-HBs than those without OBI but all eight OBI babies with second follow-up samples became HBV DNA negative beyond 1 year of age. The vaccinated infants born to HBsAg+ mothers presented the low rate of HBsAg occurrence as vaccination failure and high frequency of viral persistence in the form of transient OBIs since no evidence of active HBV infection occurred beyond 1 year of age. © 2017 Wiley Periodicals, Inc.

  12. Delayed clearance of serum HBsAg in compensated cirrhosis B

    DEFF Research Database (Denmark)

    Fattovich, G; Giustina, G; Sanchez-Tapias, J

    1998-01-01

    The aim of this study was to evaluate the incidence, prognostic factors and clinical significance of delayed clearance of serum HBsAg in compensated cirrhosis B.......The aim of this study was to evaluate the incidence, prognostic factors and clinical significance of delayed clearance of serum HBsAg in compensated cirrhosis B....

  13. Viral hepatitis and rapid diagnostic test based screening for HBsAg in HIV-infected patients in rural Tanzania.

    Directory of Open Access Journals (Sweden)

    Fabian C Franzeck

    Full Text Available BACKGROUND: Co-infection with hepatitis B virus (HBV is highly prevalent in people living with HIV in Sub-Saharan Africa. Screening for HBV surface antigen (HBsAg before initiation of combination antiretroviral therapy (cART is recommended. However, it is not part of diagnostic routines in HIV programs in many resource-limited countries although patients could benefit from optimized antiretroviral therapy covering both infections. Screening could be facilitated by rapid diagnostic tests for HBsAg. Operating experience with these point of care devices in HIV-positive patients in Sub-Saharan Africa is largely lacking. We determined the prevalence of HBV and Hepatitis C virus (HCV infection as well as the diagnostic accuracy of the rapid test device Determine HBsAg in an HIV cohort in rural Tanzania. METHODS: Prospectively collected blood samples from adult, HIV-1 positive and antiretroviral treatment-naïve patients in the Kilombero and Ulanga antiretroviral cohort (KIULARCO in rural Tanzania were analyzed at the point of care with Determine HBsAg, a reference HBsAg EIA and an anti-HCV EIA. RESULTS: Samples of 272 patients were included. Median age was 38 years (interquartile range [IQR] 32-47, 169/272 (63% subjects were females and median CD4+ count was 250 cells/µL (IQR 97-439. HBsAg was detected in 25/272 (9.2%, 95% confidence interval [CI] 6.2-13.0% subjects. Of these, 7/25 (28% were positive for HBeAg. Sensitivity of Determine HBsAg was rated at 96% (95% CI 82.8-99.6% and specificity at 100% (95% CI, 98.9-100%. Antibodies to HCV (anti-HCV were found in 10/272 (3.7%, 95% CI 2.0-6.4% of patients. CONCLUSION: This study reports a high prevalence of HBV in HIV-positive patients in a rural Tanzanian setting. The rapid diagnostic test Determine HBsAg is an accurate assay for screening for HBsAg in HIV-1 infected patients at the point of care and may further help to guide cART in Sub-Saharan Africa.

  14. [Comparison of the clinical performance of the ECLusys HBsAg II assay with the Lumipulse f and HISCL 2000-i HBsAg screening assays].

    Science.gov (United States)

    Sugiura, Aya; Iwahara, Kunihiro; Suga, Yasuyuki; Uchiyama, Sachinori; Maekawa, Masato

    2012-02-01

    We compared the ECLusys HBsAgII (ECL HBsAg) assay to the Lumipulse Forte (LPf HBsAg) and HISCL (HIS HBsAg) assays. Measurement of dilution panels for which the WHO HBsAg international reference panel was the parent specimen revealed that the ECL and HIS assays enabled detection to a theoretical level of 0.04 IU/mL, whereas the LPf assay enabled detection to a level of 0.08 IU/mL. In a specificity test using high RF positive specimens (n = 33), pregnancy specimens (n = 35), cytomegalovirus antibody positive specimens (n = 36), and high M protein positive specimens (n = 21) that were confirmed negative for HBsAg by the LPf assay, negative results were obtained for all specimens on the HIS assay, but the ECL assay yielded a positive result for one of the high RF positive specimens. This individual was suggested on further testing to be an HBV carrier who was strongly positive for HBc antibody. In HBsAg mutants detection test, the detection rate was 92.3% with the ECL assay and 69.2% with the HIS assay. In a correlation test using routinely collected clinical specimens (n = 155), including positive stock specimens, aside from the one case where the LPf assay gave a negative result but both the ECL and HIS assays gave positive results, all of the results were consistent for all specimens. The above results confirmed that the ECL assay is both highly sensitive and specific, and also enables a high rate of HBsAg mutant detection.

  15. HBsAg positivity during pregnancy and adverse maternal outcomes: a retrospective cohort analysis.

    Science.gov (United States)

    Tan, J; Liu, X; Mao, X; Yu, J; Chen, M; Li, Y; Sun, X

    2016-10-01

    Hepatitis B virus infection characterized by HBsAg positivity during pregnancy is a well-recognized issue in developing countries, but the association between HBsAg positivity and adverse maternal outcomes remains uncertain. To examine the association between HBsAg positivity during pregnancy and adverse maternal outcomes, a retrospective cohort study was conducted in Sichuan province, China. Deliveries were recorded from six hospitals between 1 January 2009 and 31 December 2010. Pre-eclampsia, gestational diabetes mellitus (GDM), postpartum haemorrhage (PPH), intrahepatic cholestasis, Caesarean section and placenta previa were prespecified adverse maternal outcomes. We used two multivariate logistic regression models to assess the association between HBsAg positivity and adverse maternal outcomes. In total, 948 (4.2%) pregnant women were HBsAg positive from 22 374 deliveries. Pregnant women with positive HBsAg had higher risk of GDM (aOR1.41, 95%CI 1.15-1.74), PPH (1.44, 1.13-1.83), intrahepatic cholestasis (1.74, 1.40-2.16) and Caesarean section (1.24, 1.06-1.45). No statistical associations were found between HBsAg positivity and pre-eclampsia (1.36, 0.94-1.97), and placenta previa (1.21, 0.87-1.67). HBsAg positivity during pregnancy was associated with higher risk of multiple adverse maternal outcomes. Although the causality has yet to be established, efforts may be warranted in routine care, particularly in those with high risk for adverse maternal outcomes, given the volume population infected with HBsAg. Future studies are needed to establish causality and examine the impact of HBeAg on the adverse outcomes. © 2016 John Wiley & Sons Ltd.

  16. GAMBARAN ANTI HBc POSITIF PADA DONOR DARAH DENGAN HbsAG NEGATIF

    Directory of Open Access Journals (Sweden)

    Susila Sastri

    2009-09-01

    Full Text Available AbstrakPemeriksaan HBsAg saja untuk skrining hepatitis B (HBV belum dapat menjamin donor darah bebas dari HBV sehingga darah donor belum memenuhi persyaratan untuk ditransfusikan. Darah donor yang akan ditranfusikan hendaklah memenuhi syarat diantaranya donor tidak pernah menderita HBV. Skrining darah donor terhadap HBV pada PMI hanya dengan uji HBsAg saja dimana HBsAg akan negatif pada stadium HBV tertentu, pada hal donor menderita atau dalam masa penyembuhan HBV. Anti-HBc dapat memberi informasi tentang perjalanan HBV bila digabungkan dengan marker HBV lain dan anti-HBc bertahan lebih lama dalam darah dibandingkan dengan marker lain. Donor darah HBsAg negatif dengan anti-HBc positif dari beberapa penelitian terdahulu masih ada yang mengandung HBV-DNA dan dapat menularkan HBV.Telah dilakukan penelitian terhadap donor darah dengan melakukan uji anti-HBc secara deskriptif terhadap donor darah dengan HBsAg negatif (n=100 pada UTD PMI Cabang Padang secara cross sectional study. Sampel diambil secara proportional random sampling. Darah sampel adalah darah HBsAg negatif dengan VDRL, HVC, HIV  negatif , semuanya diperiksa dengan dengan ELISATujuan penelitian untuk melihat gambaran anti-HBc positif pada donor darah dengan HBsAg negatif dan melihat hubungan antara indeks HBsAg dengan indeks anti-HBc. Pemeriksaan anti-HBc dilakukan dengan ELISA, alat dan reagen keluaran yang sama.Hasil penelitian menunjukkan frekuensi anti-HBc positif pada donor darah dengan HBsAg negatif sebanyak 27%, terutama pada laki-laki berumur antara 20-29 tahun (44,4%. Terdapat korelasi positif antara indeks HBsAg negatif dengan indeks anti-HBc (r = 0,02. Anti-HBc positif banyak ditemukan pada indeks HBsAg negatif 0,21-0,60 (76%.Kesimpulan, darah donor dengan HBsAg negatif yang selama ini dianggap aman untuk transfusi terbukti masih mungkin menularkan HBV dengan ditemukannya anti-HBc yang positif. Karena itu perlu pemeriksaan lanjutan DNA HBV pada donor darah dengan HbsAg

  17. Mutation in the S gene a determinant of the hepatitis B virus associated with concomitant HBsAg and anti-HBs in a population in Northeastern Brazil.

    Science.gov (United States)

    de Campos Albuquerque, Ingrid; Sousa, Marinilde Teles; Santos, Max Diego Cruz; Nunes, Jomar Diogo Costa; Moraes, Maria Josélia Diniz; Gomes-Gouvêa, Michele Soares; Pinho, João Renato Rebelo; Carrilho, Flair José; Fonseca, Lena Maria Barros; de Sousa Paiva Ferreira, Adalgisa

    2017-03-01

    Mutations in the a determinant of S gene may develop co-existence of hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs) in the serum of infected hepatitis B virus (HBV) individuals. Mutations in this region may change the antigenicity of HBsAg, which in turn, lead to escape of neutralizing action of anti-HBs antibodies. This study identified individuals with concomitant HBsAg and anti-HBs serological markers in individuals of Maranhão, Northeastern Brazil. Samples from a population-based study were evaluated for HBsAg, anti-HBs, and anti-HBc, and those that tested positive for simultaneous HBsAg and anti-HBs were submitted to HBV DNA quantification and S gene characterization by Sanger sequencing. Mutations were investigated in the a determinant located in major hydrophilic region (MHR) of the S gene. Among 3,984 samples analyzed, 92 (2.3%) were positive for HBsAg and three had the atypical HBsAg and anti-HBs-positive profile (3.26%). The frequency of HBsAg and anti-HBs co-existence was similar to previous studies. Only one individual harbored mutation in the S gene a determinant associated with this profile. Little is known about this phenomenon; however, studies as ours may contribute for future enlightenment of this important issue. J. Med. Virol. 89:458-462, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  18. Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg

    Directory of Open Access Journals (Sweden)

    Jackson Marcondes

    Full Text Available The obtainment of transgenic edible plants carrying recombinant antigens is a desired issue in search for economic alternatives viewing vaccine production. Here we report a strategy for genetic transformation of lettuce plants (Lactuca sativa L. using the surface antigen HBsAg of hepatitis B virus. Transgenic lettuce seedlings were obtained through the application of a regulated balance of plant growth regulators. Genetic transformation process was acquired by cocultivation of cotyledons with Agrobacterium tumefaciens harboring the recombinant plasmid. It is the first description of a lettuce Brazilian variety "Vitória de Verão" genetically modified.

  19. Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg.

    Science.gov (United States)

    Marcondes, Jackson; Hansen, Ekkehard

    2008-12-01

    The obtainment of transgenic edible plants carrying recombinant antigens is a desired issue in search for economic alternatives viewing vaccine production. Here we report a strategy for genetic transformation of lettuce plants (Lactuca sativa L.) using the surface antigen HBsAg of hepatitis B virus. Transgenic lettuce seedlings were obtained through the application of a regulated balance of plant growth regulators. Genetic transformation process was acquired by cocultivation of cotyledons with Agrobacterium tumefaciens harboring the recombinant plasmid. It is the first description of a lettuce Brazilian variety 'Vitória de Verão' genetically modified.

  20. Biochemical and biophysical characterization of maize-derived HBsAg for the development of an oral vaccine.

    Science.gov (United States)

    Shah, Shweta; Hayden, Celine A; Fischer, Maria E; Rao, A Gururaj; Howard, John A

    2015-12-15

    Although a vaccine against hepatitis B virus (HBV) has been available since 1982, it is estimated that 600,000 people die every year due to HBV. An affordable oral vaccine could help alleviate the disease burden and to this end the hepatitis B surface antigen (HBsAg) was expressed in maize. Orally delivered maize material induced the strongest immune response in mice when lipid was extracted by CO2 supercritical fluid extraction (SFE), compared to full fat and hexane-extracted material. The present study provides a biochemical and biophysical basis for these immunological differences by comparing the active ingredient in the differently treated maize material. Purified maize-derived HBsAg underwent biophysical characterization by gel filtration, transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-CD, and fluorescence. Gel filtration showed that HBsAg forms higher-order oligomers and TEM demonstrated virus-like particle (VLP) formation. The VLPs obtained from SFE were more regular in shape and size compared to hexane or full fat material. In addition, SFE-derived HBsAg showed the greatest extent of α-helical structure by far UV-CD spectrum. Fluorescence experiments also revealed differences in protein conformation. This work establishes SFE-treated maize material as a viable oral vaccine candidate and advances the development of the first oral subunit vaccine. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Identified OAS3 gene variants associated with coexistence of HBsAg and anti-HBs in chronic HBV infection.

    Science.gov (United States)

    Wang, Sa; Wang, Jing; Fan, Mengjie; Li, Tengyan; Pan, Hong; Wang, Xi; Liu, Hankui; Lin, Qiongfen; Zhang, Jianguo; Guan, Liping; Zhernakova, Daria V; O'Brien, Stephen J; Feng, Zhenru; Chang, Le; Dai, Erhei; Lu, Jianhua; Xi, Hongli; Zeng, Zheng; Yu, Yanyan; Wang, Binbin

    2018-03-27

    The underlying mechanism of coexistence of hepatitis B surface antigen (HBsAg) and hepatitis B surface antigen antibody (anti-HBs) is still controversial. To identify the host genetic factors related to this unusual clinical phenomenon, a two-staged study was conducted in the Chinese Han population. In the first stage, we performed a case-control (1:1) age, gender matched study of 101 cases with concurrent HBsAg and anti-HBs and 102 controls with negative HBsAg and positive anti-HBs using whole exome sequencing. In the second validation stage, we directly sequence the 16 exomes on the OAS3 gene in two dependent cohorts of 48 cases and 200 controls. Although in the first stage, a genome-wide association study of 58,563 polymorphism variants in 101 cases and 102 controls found no significant loci (P-value ≤ 0.05/58563), and neither locus achieved a conservative genome-wide significance threshold (P-value ≤ 5e-08), gene burden analysis showed that OAS3 gene rare variants were associated with the coexistence of HBsAg and anti-HBs. (P-value =4.127e-06 ≤ 0.05/6994). 16 rare variants were screened out from 21 cases and 3 controls. In the second validation stage, one case with a new different rare variant was identified. Fisher's exact test of all 149 cases and 302 controls showed that the rare coding-sequence mutations were more frequent in cases versus controls [P-value=7.299e-09, OR=17.27, 95% CI (5.01-58.72)]. Protein-coding rare variations on the OAS3 gene are associated with the coexistence of HBsAg and anti-HBs in patients with chronic HBV infection in Chinese Han population. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Understanding early serum hepatitis D virus and HBsAg kinetics during pegylated interferon-alfa therapy via mathematical modeling

    Science.gov (United States)

    Guedj, Jeremie; Rotman, Yaron; Cotler, Scott J.; Koh, Christopher; Schmid, Peter; Albrecht, Jeff; Haynes-Williams, Vanessa; Liang, Jake T.; Hoofnagle, Jay H.; Heller, Theo; Dahari, Harel

    2014-01-01

    There is little information on the early kinetics of hepatitis delta virus (HDV) and hepatitis B surface antigen (HBsAg) during interferon-α therapy. Here a mathematical model was developed and fitted to frequent HDV and HBsAg kinetic data from 10 patients during the first 28 weeks of pegylated-interferon-α2a (peg-IFN) therapy. Three patients achieved a complete virological response (CVR), defined as undetectable HDV 6 months after treatment stopped with loss of HBsAg and anti-HBsAg seroconversion. After initiation of therapy a median delay of 9 days (interquartile range IQR:[5;15]) was observed with no significant changes in HDV level. Thereafter, HDV declined in a biphasic manner, where a rapid first-phase lasting for 25 days (IQR:[23;58]) was followed by a slower or plateau second-phase. The model predicts that the main effect of peg-IFN is to reduce HDV production/release with a median effectiveness of 96% (IQR:[93;99.8]). Median serum HDV half-life (t1/2) was estimated to 2.9 days (IQR:[1.5;5.3]) with pretreatment production and clearance of about 1010 (IQR:[109.8-1010.8]) virions/day. None of the patients with flat 2nd phase in HDV achieved CVR. HBsAg kinetics of decline paralleled the second-phase of HDV decline consistent with HBsAg-productive-infected cells being the main source of production of HDV, with a median t1/2 of 135 days (IQR:[20-460]. The interferon lambda-3 polymorphism (rs12979860) was not associated with kinetic parameters. Conclusions Modeling results provide insights into HDV-host dynamics, the relationship between serum HBsAg levels and HBsAg-infected cells, IFN's mode of action and its effectiveness. The observation that a flat second phase in HDV and HBsAg kinetics was associated with failure to achieve CVR provides the basis to develop early stopping rules during peg-IFN treatment in HDV-infected patients. PMID:25098971

  3. Association of social class in HBsAg and hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Pervez, T.; Anwar, M. S.

    2001-01-01

    Objective: To find out the social class difference in relation to frequency of HBsAg and hepatocellular carcinoma in our population. Design: An analytical study. Place and Duration of Study: This study was conducted in Oncology Department, Services Hospital, Lahore from December 1997 to December 2000. Subjects and Methods: The HBsAg positive voluntary and apparently healthy blood donors were grouped into three, based on monthly income. Lower socioeconomic group and had monthly income less than 3,000 Pakistani rupees, middle socioeconomic group had monthly income between 3,000-10,000 rupees and upper socioeconomic group had income of more than 10,000 Pakistani rupees. On the same pattern patients suffering from hepatocellular carcinoma coming for treatment were also grouped. During this period, 1000 blood donors were screened for HBsAg and 95 biopsy proven liver cancer by causes were treated. Medical and demographic data of all subjects were recorded. HBsAg test was performed immuno-chromatographic technique using Daina Screen HBsAg kit manufactured by Dainabot Co. Ltd, Tokyo, Japan. Results: Patients from lower and middle social class had higher percentage (80% and 75%) of hepatocellular carcinoma as compared to higher social class (66.6%). In the healthy asymptomatic blood donors lower social class had higher (13.76%) HBsAg positively as compared to middle social class (11.25%) and higher social class (8.06%). Conclusion: Preventive measures should be taken in identifying and reducing factors predisposing high frequency of these conditions. (author)

  4. Quantitative HBsAg and HBeAg predict hepatitis B seroconversion after initiation of HAART in HIV-HBV coinfected individuals.

    Directory of Open Access Journals (Sweden)

    Gail V Matthews

    Full Text Available OBJECTIVE: Anti-HBe seroconversion and HBsAg loss are important therapeutic endpoints in patients with hepatitis B virus (HBV infection. Quantitative measures of hepatitis B surface antigen (qHBsAg and e antigen (qHBeAg have been identified as potentially useful indicators of therapeutic response in HBV monoinfection. The aim of this study was to examine serological change including quantitative biomarkers in HIV-HBV coinfected patients initiating HBV active antiretroviral therapy (ART. METHODS: HIV-HBV coinfected individuals from Thailand were followed for up to 168 weeks post ART. Rates and associations of qualitative serological change were determined. Longitudinal changes in qHBsAg and qHBeAg were measured and their utility as predictors of response examined. RESULTS: Forty seven patients were included of whom 27 (57% were HBeAg positive at baseline. Median CD4 count was 48 cells/mm(3. Over a median follow-up of 108 weeks 48% (13/27 lost HBeAg, 12/27 (44% achieved anti-HBe seroconversion and 13% (6/47 HBsAg loss. Anti-HBe seroconversion was associated with higher baseline ALT (p = 0.034, lower qHBsAg (p = 0.015, lower qHBeAg (p = 0.031 and greater HBV DNA decline to week 24 (p = 0.045. Sensitivity and specificity for qHBsAg and qHBeAg decline of >0.5 log at week 12 and >1.0 log at week 24 were high for both anti-HBe seroconversion and HBsAg loss. CONCLUSIONS: Rates of serological change in these HIV-HBV coinfected individuals with advanced immunodeficiency initiating HBV-active ART were high. Baseline and on treatment factors were identified that were associated with a greater likelihood of subsequent anti-HBe seroconversion, including both quantitative HBsAg and HBeAg, suggesting these biomarkers may have utility in this clinical setting.

  5. Triple positivity of HBsAg, anti-HCV antibody, and HIV and their ...

    African Journals Online (AJOL)

    Background: Few studies exist on hospital-based seroprevalence of triple positivity of HIV/HBV/HCV in Nigeria. Objectives: The study aimed at determining the triple positivity of HIV, HBsAg and HCV among HIV-infected individuals in Abeokuta, Nigeria and defining the influence of these triple infections on CD4+ counts of ...

  6. Posintro™-HBsAg, a modified ISCOM including HBsAg, induces strong cellular and humoral responses

    DEFF Research Database (Denmark)

    Schiött, Asa; Larsson, Kristina; Manniche, Søren

    2011-01-01

    HBsAg vaccine formulation, Posintro™-HBsAg, was compared to two commercial hepatitis B vaccines including aluminium or monophosphoryl lipid A (MPL) and the two adjuvant systems MF59 and QS21 in their efficiency to prime both cellular and humoral immune responses. The Posintro™-HBsAg induced...... of delayed type hypersensitivity (DTH) reaction and CD4(+) T-cell proliferation. In addition, Posintro™-HBsAg was the only vaccine tested that also induced a strong cytotoxic T lymphocyte (CTL) response, with high levels of antigen specific CD8 T-cells secreting IFN-gamma mediating cytolytic activity...

  7. The risk of transmission of hepatitis B from HBsAg(-), HBcAb(+), HBIgM(-) organ donors.

    Science.gov (United States)

    Wachs, M E; Amend, W J; Ascher, N L; Bretan, P N; Emond, J; Lake, J R; Melzer, J S; Roberts, J P; Tomlanovich, S J; Vincenti, F

    1995-01-27

    Liver allografts from HBcAb(+), IgM(-), HBsAg(-) donors can transmit HBV to uninfected recipients. We currently no longer accept these livers for transplantation while continuing to accept the kidneys. The purpose of this study is to determine the risk of donor-transmitted HBV infections from HBcAb(+), HBIgM(-), HBsAg(-) organ donors and determine if the risk of donor-transmitted HBV infections and their severity is dependent on the organ being transplanted. This study consists of a retrospective review of the posttransplant course of recipients of HBcAb(+), HBIgM(-), HBsAg(-) donors accepted at UCSF from 6/85 to 12/93. Transmitted HBV infection was defined as one in which the recipient changed from HBsAg(-) prior to transplantation to HBsAg(+) posttransplant, with no other source. There were 25 of 1190 donors who were HBcAb(+), HBIgM(-), HBsAg(-); 1/42 kidney, 3/6 liver, and 0/7 heart HBsAg(-) transplant recipients of organs from these donors became HBsAg(+) after transplantation. This difference in infection rate (liver vs. kidney and heart) is statistically significant. The clinical course of the liver recipients was also more severe. All of the patients who became infected were HBsAb(-) and HBcAb(-) prior to transplant. We conclude that (1) HBV can be transmitted from HBcAb(+), HBIgM(-), HBsAg(-) organ donors, (2) the rate of transmission is highest and severity of infection is worst in the liver recipients; and (3) we will continue to transplant kidneys from these donors, preferably into immunized recipients.

  8. Seven-Year Treatment Outcome of Entecavir in a Real-World Cohort: Effects on Clinical Parameters, HBsAg and HBcrAg Levels.

    Science.gov (United States)

    Lam, Yuk-Fai; Seto, Wai-Kay; Wong, Danny; Cheung, Ka-Shing; Fung, James; Mak, Lung-Yi; Yuen, John; Chong, Chun-Kong; Lai, Ching-Lung; Yuen, Man-Fung

    2017-10-26

    We aimed to determine the levels of alanine aminotransferase (ALT), hepatitis B virus DNA (HBV DNA), HBsAg, and a novel viral marker (hepatitis B core-related antigen (HBcrAg)); hepatitis B e antigen (HBeAg) seroconversion and drug resistance rates after 7 years of entecavir treatment in chronic hepatitis B (CHB) patients. Two hundred and twenty-two Chinese CHB patients on continuous entecavir treatment were recruited. Serologic, virologic, biochemical outcomes, and the occurrence of entecavir signature mutations were determined. The rates of ALT normalization, HBeAg seroconversion, and undetectable HBV DNA were 98.3%, 82.1%, and 98.7%, respectively, after 7 years of entecavir treatment. The genotypic resistance rate was 1.2%. Decline of HBsAg level was modest with a median decline rate of 0.107 log IU/ml/year. Among patients with baseline HBsAg <1,000 IU/ml and annual HBsAg decline rate of ≥0.166 log IU/ml, all have HBsAg of <200 IU/ml (a level highly predictive for HBsAg seroclearance) at year 7. In contrast, in patients with baseline HBsAg ≥1,000 IU/ml and annual HBsAg decline rate of <0.166 log IU/ml, 95.5% had HBsAg of ≥200 IU/ml at year 7. Decline of HBcrAg levels was moderate with a median decline rate of 0.244 log kU/ml/year. Forty-seven patients (32.0%) had undetectable HBcrAg level at year 7. Long-term entecavir therapy continued to have good responses with low drug resistance rate. However, the decline of HBsAg with treatment was suboptimal. HBcrAg level declined at a relatively better rate. Baseline HBsAg level of <1,000 IU/ml and annual decline of 0.166 log IU/ml could be used to predict HBsAg response.

  9. ALT flares during nucleotide analogue therapy are associated with HBsAg loss in genotype A HBeAg-positive chronic hepatitis B.

    Science.gov (United States)

    Wong, Darren; Littlejohn, Margaret; Edwards, Rosalind; Jackson, Kathy; Revill, Peter; Gaggar, Anuj; Kitrinos, Kathryn; Subramanian, Mani; Marcellin, Patrick; Buti-Ferret, Maria; Janssen, Harry; Gane, Ed; Locarnini, Stephen; Thompson, Alexander

    2018-02-10

    Alanine aminotransferase (ALT) flares during NA therapy are uncommon but occur. Evaluation of ALT flares during nucleos(t)ide analogue (NA) therapy is important as new immunomodulatory therapies for hepatitis B virus (HBV) are developed. We evaluated the association between ALT flares and HBsAg loss during long-term therapy for genotype A CHB. This analysis included genotype A subjects from a phase III study of tenofovir vs adefovir in HBeAg-positive HBV. ALT flare was defined as (i) a rise in ALT >2x ULN from normal ALT levels; or (ii) a rise in ALT >2x baseline ALT level. HBsAg response at week 384 was recorded as one of HBsAg loss vs HBsAg decline (≥1 log 10  IU/mL decline) vs non-response. The primary analysis evaluated the association between ALT flare and HBsAg response. 54 subjects were included. 23/54 (43%) subjects experienced an on-treatment ALT flare. 45% achieved an HBsAg reduction ≥1 log 10  IU/mL, and of these 67% achieved HBsAg loss at a median of 102 weeks [IQR: 64-156]. Flare was associated with HBsAg decline vs non-response (67% vs 23%, P = .002), and were more common in subjects who achieved HBsAg loss vs non-response (56% vs 23%), P = .049). There was a median delay of 56 weeks [IQR: 40-80] between a flare and HBsAg loss. In genotype A subjects undergoing long-term NA therapy, ALT flares predict for HBsAg response. The delay between ALT flare and HBsAg loss has implications for clinical trial design for early phase development of immunomodulatory strategies aiming for HBsAg loss. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. A Intervention Study to Improve HBsAg Testing and Preventive Practices for Hepatitis B in an Obstetrics Hospital

    Directory of Open Access Journals (Sweden)

    Ibrahim Koruk

    2011-06-01

    Full Text Available Objectives: This study was conducted to determine the effectiveness of a multicomponent intervention in Sanliurfa Gynecology and Obstetrics Hospital (SGOH, which is designed to overcome the obstacles encountered in the application of HBsAg testing to all delivering women, the administration of hepatitis B vaccine and Hepatitis B Immunglobulin(HBIG to newborns of HBsAg positive pregnant women. Methods: This is an intervention study, conducted between December 15, 2007 and December 30, 2008. Intervention procedure is composed of four methods; namely, motivation of all parties through academic leadership, implementation of workshops to determine the obstacles, provision of administrative commitment, and training of healthcare personnel. Results: In 2007, a total of 18,709 deliveries were realized in SGOH; HBsAg testing was performed in only 16.5% of the pregnant women and 0.8% of these women were found to be HBsAg positive. It was determined that HBIG was administered to 28.2% of newborns of HBsAg positive mothers and hepatitis B vaccine was given to 71.4% (n=13349 of all newborns. After the intervention, the increase in HBsAg test application status, HBsAg positivity, HIBG administration and hepatitis B vaccination was 6.0, 5.8, 2.0 and 1.2 fold, respectively (P<0.05. Conclusions: In order to reduce the incidence of hepatitis B and maintain patient safety in newborns, HBsAg testing should be included in routine pregnancy screening programs and this approach should be supported by legal arrangements and systematic continuous training activities. [TAF Prev Med Bull 2011; 10(3.000: 287-292

  11. Reactivation of viral replication in anti-HBe positive chronic HBsAg carriers

    DEFF Research Database (Denmark)

    Krogsgaard, K; Aldershvile, J; Kryger, Peter

    1990-01-01

    Reactivation of hepatitis B virus replication was investigated in an unselected group of 44 HBV DNA negative, anti-HBe positive chronic HBsAg carriers. Twenty-five patients (54%) were intravenous drug addicts and 7 (16%) were male homosexuals. Sixteen patients had evidence of delta infection...... and five of the seven male homosexuals had human immunodeficiency virus infection. The patients were followed for 1 to 180 months (median, 24 months) while HBV DNA negative, anti-HBe positive. Reactivation, defined as reappearance of HBV DNA or HBeAg, or both, was detected in six patients corresponding...... to an annual reactivation rate of 5%. Reactivation in four patients was detected by reversion to HBV DNA positivity only, whereas HBeAg/anti-HBe status remained unchanged. Two patients became both HBV DNA and HBeAg positive. None of the patients developed hepatitis-like symptoms and transaminase elevation...

  12. Evaluation of HBsAg and anti-HBc assays in saliva and dried blood spot samples according HIV status.

    Science.gov (United States)

    Flores, Geane Lopes; Cruz, Helena Medina; Potsch, Denise Vigo; May, Silvia Beatriz; Brandão-Mello, Carlos Eduardo; Pires, Marcia Maria Amendola; Pilotto, Jose Henrique; Lewis-Ximenez, Lia Laura; Lampe, Elisabeth; Villar, Livia Melo

    2017-09-01

    Influence of HIV status in HBV markers detection in saliva and dried blood spots (DBS) was not well established. This study aims to evaluate the performance of optimized commercial immunoassay for identifying HBsAg and anti-HBc in saliva and DBS according HIV status. A sum of 535 individuals grouped as HIV + , HBV + , HIV/HBV + and HIV/HBV- were recruited where 347 and 188 were included for HBsAg and anti-HBc evaluation, respectively. Serum, DBS collected in Whatman 903 paper and saliva obtained using salivette device were analyzed using EIA. Increased sample volume and ROC curve analysis for cut off determination were used for DBS and saliva testing. HBsAg detection in saliva and DBS exhibited sensitivities of 80.9% and 85.6% and specificities of 86.8% and 96.3%. Sensitivity of anti-HBc in saliva and DBS were 82.4% and 76.9% and specificities in saliva and DBS were 96.9% and 91.7%. Low sensitivities were observed for HBsAg (62%) and anti-HBc (47%) detection in saliva of HIV/HBV+ individuals. OD values were also lower for HBsAg detection in DBS and saliva of HIV/HBV+ individuals compared to their serum samples. Statistical significance was found for sensitivities in HBsAg detection between saliva and DBS demonstrating high sensitivity for DBS specimens. In conclusion, HIV status or antiretroviral treatment appears to interfere in the performance of HBsAg and anti-HBc detection in DBS and saliva samples using the adapted commercial EIA. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Historic and current hepatitis B viral DNA and quantitative HBsAg level are not associated with cirrhosis in non-Asian women with chronic hepatitis B.

    Science.gov (United States)

    Harkisoen, S; Arends, J E; van den Hoek, J A R; Whelan, J; van Erpecum, K J; Boland, G J; Hoepelman, A I M

    2014-12-01

    Some studies done in Asian patients have shown that serum levels of hepatitis B virus (HBV) DNA predict the development of cirrhosis. However, it is unclear whether this also applies for non-Asian patients. This study investigated historic and current HBV DNA and quantitative hepatitis B surface antigen (HBsAg) levels as predictors of cirrhosis in non-Asian women with chronic HBV. A retrospective cohort study of non-Asian women with chronic HBV was performed. Among other variables, HBV DNA and quantitative HBsAg levels were measured in stored historic serum samples obtained during pregnancy (period 1990-2004) and current serum samples (period 2011-2012) to determine any association with liver cirrhosis by liver stiffness measurement (LSM). One hundred and nineteen asymptomatic, treatment-naïve non-Asian women were included; the median number of years between the historic sample and the current sample was 17 (interquartile range (IQR) 13-20). The median historic log HBV DNA and quantitative log HBsAg levels were 2.5 (IQR 1.9-3.4) IU/ml and 4.2 (IQR 3.6-4.5) IU/ml, respectively. LSM diagnosed 14 patients (12%) with F3-F4 fibrosis, i.e. stiffness >8.1kPa. No association of cirrhosis was found with historic HBV DNA (relative risk (RR) 0.34, 95% confidence interval (CI) 0.05-2.44) or with the quantitative HBsAg level (HBsAg level >1000 IU/ml, RR 0.35, 95% CI 0.11-1.11). Multivariable analysis identified alcohol consumption (odds ratio (OR) 6.4, 95% CI 1.3-30.1), aspartate aminotransferase >0.5 times the upper limit of normal (OR 15.4, 95% CI 1.9-122.6), and prothrombin time (OR 12.0, 95% CI 1.2-120.4), but not HBV DNA or quantitative HBsAg level, to be independent predictors of the presence of cirrhosis. Neither historic nor current HBV DNA or the quantitative HBsAg level is associated with the development of HBV-related cirrhosis in non-Asian women. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. [A retrospective study on HBsAg clearance rate after antiviral therapy in children with HBeAg-positive chronic hepatitis B aged 1-7 years].

    Science.gov (United States)

    Zhu, S S; Dong, Y; Xu, Z Q; Wang, L M; Chen, D W; Gan, Y; Wang, F C; Yan, J G; Cao, L L; Wang, P; Zhang, H F

    2016-10-20

    Objective: To investigate the HBsAg clearance rate after antiviral therapy in children with HBeAg-positive chronic hepatitis B (CHB) aged 1-7 years. Methods: A retrospective analysis was performed for the HBsAg clearance rate in 293 children who were hospitalized in 302 Hospital of PLA from June 2006 to December 2013, met the inclusion criteria, received antiviral therapy, and were followed up for at least 6 months after the withdrawal of antiviral therapy. The t-test or the rank sum test was applied according to the distribution of continuous data, and the chi-square test was used for comparison of categorical data. Results: The HBsAg positive rate of children's mothers was 91.1%. In the age groups of >1-≤2 years, >2-≤3 years, >3-≤4 years, >4-≤5 years, >5-≤6 years, and >6-≤7 years, the HBsAg clearance rates were 66.1%, 65.5%, 45.7%, 41.3%, 20.6%, and 27.6%, respectively. There were significant differences in HBsAg clearance rate between the age groups of >1-≤3 years and >3-≤5 years, >1-≤3 years and >5-≤7 years, and >3-≤5 years and >5-≤7 years ( P = 0.001, 0.000, and 0.008). Of all children, 64.8% were boys, among whom 41.1% achieved HBsAg clearance, and 35.2% were girls, among whom 61.2% achieved HBsAg clearance; there was a significant difference in HBsAg clearance rate between boys and girls (P = 0.001). The children with pretreatment alanine aminotransferase (ALT) levels of ≤80 IU/L, > 80 IU/L, ≤200 IU/L, and > 200 IU/L had HBsAg clearance rates of 40.7%, 51.2%, 47.6%, and 49.4%, respectively; there were no significant differences in HBsAg clearance rate between the ALT ≤80 IU/L and ALT > 80 IU/L groups and the ALT ≤200 IU/L and ALT > 200 IU/L groups ( P = 0.101 and 0.778). There was no significant difference in HBsAg clearance rate between the pretreatment HBV DNA load antiviral therapy alone and had an HBsAg clearance rate of 48.8%, and 41.3% received interferon alone for 6 months followed by lamivudine antiviral therapy and

  15. Incidência pós-transfusional do HBsAg em crianças com doenças neoplásicas Post-transfusional incidence of HBsAg in children with neoplastic diseases

    Directory of Open Access Journals (Sweden)

    Maria Zélia Fernandes

    2009-04-01

    newborn babies. An individual who is chronically infected by HBV during childhood has a 25% risk of dying due to cirrhosis or liver cancer. This data led the authors to design a study with the objective of estimating the post-transfusion incidence of the hepatitis B virus surface antigen (HBsAg in children with neoplasias who were transfused during treatment or during the follow up. A retrospective study was performed that revisited 333 medical records from the oncology service in the HIVS from January 1993 to January 2005. The inclusion criteria were: age less than 16 years old, diagnosis of cancer and the results of the HBsAg test. Thus, 199 patients were excluded because they did not fulfill the criteria. The remaining 134 patients’ records were analyzed in regards to blood transfusion. Of the 134 children who satisfied the criteria, 116 were transfused and 18 were not. Results of the HBsAg test were positive in 32.8% of the transfused patients and in only 5.6% of non-transfused individuals. The Fisher Exact Test demonstrated a statistically significant difference (p = 0.023. The ODDS ratio of a transfused patient presenting with reactive results for HBsAG was calculated at 8.28 times greater than non-transfused individuals.

  16. Evidenciação de antígeno da hepatite B (HBsAg em "manchas" obtidas de exemplares de Triatominae: nota prévia Hepatitis B antigen (HBsAg in wildcaught Triatominae in Brazil: communication

    Directory of Open Access Journals (Sweden)

    J. A. N. Candeias

    1976-09-01

    Full Text Available De 890 "manchas" provenientes de insetos dos gêneros Panstrongylus, Rhodnius e Triatoma, positivas para sangue humano, 7 deram resultados presumptivamente positivos por hemaglutinação passiva para HBsAg. Deste total só um caso foi confirmado como positivo, por RIE (radioimunoensaio, correspondendo a uma "mancha" obtida de Triatoma sordida (ninfa de 5.º estádio.A total of 890 impressions on filter paper identified as containing human blood, were examined for the presence of hepatitis B antigen (HBsAg, using the Hepanosticon haemagglutination and radioimmunoassay techniques. The samples examined belong to the Panstrongylus, Rhodnius and Triatoma genres. The Hepanosticon haemagglutination technique showed that 7 impressions, after elution, were presumably positive for HBsAg, but by radioimmunoassay, this antigen could only be detected in 1. The positive sample was obtained from a specimen of Triatoma sordida (fifth instar nymph.

  17. Results of HBsAg examination with immunoelectrophoresis and radioimmunoassay in VPR, Laotian PDR and Cuban R

    Energy Technology Data Exchange (ETDEWEB)

    Michal, L.; Szilagyiova, M.; Zahradny, V.; Holan, J.; Krajnak, V. (Komenskeho Univ., Martin (Czechoslovakia). Lekarska Fakulta); Padurova, J. (Okresna Hygienicka Stanica, Zilina (Czechoslovakia))

    1984-06-21

    The results are compared of examining 112 Vietnamese, 30 Laotian and 50 Cuban citizens for HBsAg using IEP and RIA methods. Of the examined persons with no liver disorders HBsAg was found in 23 (31.5%) of the Vietnamese and 1 (2.5%) of the Cubans using the RIA method and only in 4 (5.5%) of the Vietnamese using the IEP method. Of the examined persons with liver disorders RIA found HBsAg in 12 (30.8%) of the Vietnamese, 5 (71.4%) of the Laotians and 2 (20.0%) of the Cubans while with IEP only in 3 (7.7%) Vietnamese 2 (28.6%) Laotians and 1 (10.0%) of the Cubans examined.

  18. Value of HBsAg level in dynamic monitoring of disease progression in patients with chronic HBV infection

    Directory of Open Access Journals (Sweden)

    BAO Teng

    2017-08-01

    Full Text Available ObjectiveTo investigate the clinical value of HBsAg level in dynamic monitoring of disease progression in patients with chronic HBV infection. MethodsA retrospective analysis was performed for the clinical data of 1107 patients with different clinical stages of chronic HBV infection who had not received antiviral therapy at the time of hospitalization in The Second Affiliated Hospital of Anhui Medical University from May 2011 to December 2015, and according to the disease status, they were divided into HBeAg-positive chronic hepatitis B (CHB group, HBeAg-negative CHB group, compensated liver cirrhosis group (LC-C group, decompensated liver cirrhosis group (LC-D group, and primary liver cancer (PLC group. These groups were compared in terms of HBsAg expression and the association between HBsAg and clinical features. An analysis of variance was used for comparison of continuous data between multiple groups, and the least significant difference t-test was used for further comparison between any two groups; the t-test was used for comparison of continuous data between two groups. The chi-square test was used for comparison of categorical data between these groups. Pearson correlation analysis was also performed. ResultsThere was a significant difference in serum HBsAg level between the HBeAg-positive CHB group, HBeAg-negative CHB group, LC-C group, LC-D group, and PLC group (F=100.45, P<0.001. The HBeAg-positive CHB group had significantly higher levels of HBsAg and HBV DNA than the HBeAg-negative CHB group (t= 16.67 an 16.22, both P<0.001. There were significant differences in HBsAg and HBV DNA levels between the HBeAg-positive CHB group, LC-C group, LC-D group, and PLC group (F= 42.92 and 27.38, both P<0.001, as well as between the HBeAg-negative CHB group, LC-C group, LC-D group, and PLC group (F=6.04 and 4.10, both P<0.05. HBV DNA level was significantly different across patients with different HBsAg levels (<1000 IU/ml, 1000-20 000 IU

  19. Detection of HBsAg and Anti HBc on donors of a blood bank by IRMA and ELISA methods

    International Nuclear Information System (INIS)

    Freire Martinez, D.Y.

    1985-10-01

    Comparative evaluation of two methods, Immunoradiometric Assay (IRMA) and Enzyme Immunoassay (ELISA), for detecting HBsAg and Anti HBc was made for determining which is the most advantageous and reliable. The study was made on 300 donors of the Hospital San Juan de Dios Blood Bank. In comparison with the reference method (IRMA), ELISA shows 91.67% of sensitivity. The Anti HBc detection by IRMA is more reliable than the HBsAg detection by IRMA and ELISA for determining the carrier state

  20. Clinical characteristics of patients with HBsAg(+ versus HBsAg(-/HBcAb(+ primary hepatic carcinoma treated by hepatectomy: a comparative analysis

    Directory of Open Access Journals (Sweden)

    YANG Keli

    2015-06-01

    Full Text Available ObjectiveTo explore the differences in clinical characteristics between patients with HBsAg(+ and HBsAg(-/HBcAb(+ primary hepatic carcinoma (PHC treated by hepatectomy. MethodsForty-three HBsAg(+ and 18 HBsAg(-/HBcAb(+ patients who underwent liver resection against PHC from October 2009 to November 2014 in Guangzhou 8th People′s Hospital were selected for the study. The clinical data of the subjects, including sex, age, histological differentiation, intravascular tumor thrombi, and hepatic cirrhosis, were compared, using t test for continuous data, chi-square test for categorical data, and Mann-Whitney U test for non-parametric data. ResultsNo significant differences existed between patients with HBsAg(+ and HBsAg(-/HBcAb(+ PHC in terms of the age of onset (50.77±12.93 years vs 54.28±9.89 years, t=-1.031, P>0.05, the incidence of cholangiocarcinoma (2.3% vs 167%, χ2=2.24, P>0.05, the incidence of hepatic cirrhosis (62.8% vs 44.4%, χ2=1.746, P>0.05, alpha-fetoprotein level (3638±7869 ng/ml vs 3577±9628 ng/ml, t=0.026, P>0.05, histological differentiation (Z=-1.085, P>0.05, and the rate of intravascular tumor thrombi (34.9% vs 22.2%, χ2=0.949, P>0.05. ConclusionThere are no significant differences in the age of onset and progression of disease between patients with HBsAg(+ and HBsAg(-/HBcAb(+ PHC treated by hepatectomy. However, given the possibility of occult hepatitis B virus infection, it is necessary to monitor hepatic carcinoma even post HBsAg seroconversion

  1. Factors Predicting HBsAg Seroclearance and Alanine Transaminase Elevation in HBeAg-Negative Hepatitis B Virus-Infected Patients with Persistently Normal Liver Function.

    Directory of Open Access Journals (Sweden)

    Tai-Long Chien

    Full Text Available A certain proportion of hepatitis B virus (HBV-infected patients with persistently normal alanine transaminase (ALT levels have significant fibrosis. Using liver stiffness measurements (Fibroscan® and laboratory data, including serum ALT, quantitative HBsAg (qHBsAg, and HBV DNA, we attempted to predict the natural histories of these patients.Non-cirrhotic HBeAg-negative chronic hepatitis B patients with persistently normal ALT were followed up prospectively with the end points of HBsAg seroclearance and ALT elevation above the upper limit of normal. The factors that were predictive of the end points were identified.A total of 235 patients with an average age of 48.1 +/- 10.7 years were followed up for 7 years. Eight patients (3.4% lost HBsAg, and 15 patients (6.4% experienced ALT elevation. The overall cumulative HBsAg seroclearances were 0.4%, 1.3% and 2.3% at years 1, 3 and 5, respectively. Regarding HBsAg seroclearance, the qHBsAg (< 30 IU/ml cutoff resulted in a hazard ratio (HR of 19.6 with a 95% confidence interval (CI of 2.2-166.7 (P = 0.008. The baseline ALT level (odd ratio (OR 1.075, 95% CI 1.020-1.132, P = 0.006 and a qHBsAg above 1000 IU/ml (3.7, 1.1-12.4, P = 0.032 were associated with ALT elevation. Limited to men, the baseline liver stiffness (1.6, 1.0-2.5, P = 0.031 and a qHBsAg above 1000 IU/ml (10.4, 2.1-52.4, P = 0.004 were factors that were independently associated with ALT elevation.A low qHBsAg level predicted HBsAg clearance. Baseline ALT and a qHBsAg above 1000 IU/ml were independent predictive factors for ALT elevation. Among the men, the independent predictive factors for ALT elevation were qHBsAg and liver stiffness.

  2. [Predictive study of HBsAg in different stages of neonatal venous blood on failure of blocking HBV mother to infant transmission].

    Science.gov (United States)

    Yi, Wei; Li, Ming-Hui; Hu, Yu-Hong; Liu, Feng; Zhang, Yang-Li; Liu, Xue-Jing; Hao, Hong-Xiao; Song, Shu-Jing; Liu, Ying; Li, Xing-Hong; Sun, Ji-Yun; Liu, Min; Cheng, Jun; Xie, Yao

    2011-10-01

    In this study, we discuss the predictive value of different content of HBsAg in different stages of neotal venous blood on failure of blocking mother to infant transmission of HBV. 150 infants born of chronically HBV infected mothers who were positive of both HBsAg and HBeAg and who also had a HBV DNA virus load above 10(5) copies/ml were enrolled. These infants were given hepatitis B virus immune globin (HBIG) 200 IU immediately after birth and were given hepatitis B vaccine 10 or 20 microg at brith, 1 month and 6 months after birth. HBV serological index of these infants were test at birth, 1 month and 7 months after birth respectively. Different content of HBsAg in different stages of neonatal venus blood were analyzed to predict the failure of blocking mother to infant transmission of HBV. 11 infants failed in blocking of HBV mother to infant transmission. The positive rate of HBsAg at birth, 1 month and 7 months after birth were 41.26%, 10.49% and 7.69% respectively, and were 97.90%, 65.73% and 13.29% of HBeAg. The positive predictive value of HBsAg > or = 0.05 and HBsAg > or = 1 IU/ml at birth were 18.64% and 70% respectively, and were 73.33% and 100% one month after birth. Infants with HBsAg > or = 1 IU/ml at birth should be suspicious of failure on blocking HBV mother-to-infant transmission and it should be more credible if the infant has HBsAg > or = 1 IU/ml one month after birth. How to improve the blocking rate of neonates who were positive of HBsAg at birth and one month after birth should be the focus of our future research.

  3. Generation of murine triomas secreting bi-specific monoclonal antibodies that recognize HBsAG ad and ay subtypes.

    Science.gov (United States)

    Falero, G; Rodríguez, I; Sarracent, J; Otero, A J; Rodríguez, B L; Rojas, A; Ochoa, E

    1992-12-01

    We report the generation of murine triomas by fusing splenocytes from mice previously immunized with HBsAg ay-subtype and a hybridoma, secreting anti-HBsAg ad-subtype monoclonal antibody, which was rendered HGPRT- by induced mutagenesis with N-methyl-N'nitro-N-nitrosoguanidine. The fusion yielded a 83.8% of hybrids showing the antigen specificity of the parental hybridoma and a 16.1% of bi-specific monoclonal antibodies. One of them, coded as 1C8A5, showing a heavy chain isotype (IgG1/IgG2b) was used as capture reagent in an ultramicro-ELISA. As little as 0.78 I.U. of both HBsAg ad- and ay-subtypes could be realiably detected.

  4. Development of an economic and efficient strategy to detect HBsAg: application of "gray-zones" in ELISA and combined use of several detection assays.

    Science.gov (United States)

    Peng, Jing; Cheng, Liming; Yin, Botao; Guan, Qing; Liu, Yanling; Wu, Shiji; Wang, Bin; Tang, Ning; Zhang, Biyu; Wang, Lian; Yang, Dongliang; Sun, Ziyong

    2011-11-20

    ELISA and CMIA are commonly used for detection of HBsAg. However, few investigations have been performed to evaluate their value in clinical practice, especially when jointly used. A reasonable and economic HBsAg testing algorithm is in great need. A total of 161,426 specimens in China were tested for 5 serum HBV markers with commonly used ELISA kits. 498 of these specimens were further tested for HBsAg by another ELISA kit, a CMIA kit and an HBsAg confirmatory assay. The sensitivities of the 2 ELISA kits were 76.21% and 88.42%, respectively. However, when using "gray-zones", the sensitivities were significantly improved to 97.43% and 96.43%. Furthermore, the combined use of the 2 ELISA kits and their "gray-zones" improved the sensitivity to 99.04%. Nevertheless, 2.91% of the samples with S/CO values below the lower "gray-zone" limits were reactive by the CMIA kit and then confirmed as HBsAg positive. However, 71.43% of the samples with HBsAg values within 0.05 and 0.10 IU/ml detected by the CMIA kit could not be confirmed. As a rational and economic strategy, combined use of "gray-zones" in ELISA and several different detection assays can significantly increase the efficiency of HBsAg detection. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Hepatitis B reactivation characterized by HBsAg negativity and anti-HbsAg antibodies persistence in haematopoietic stem cell transplanted patient after lamivudine withdrawal.

    Science.gov (United States)

    Cerva, C; Maffongelli, G; Svicher, V; Salpini, R; Colagrossi, L; Battisti, A; Mariotti, B; Cerretti, R; Cudillo, L; Sarmati, L

    2017-08-15

    HBV reactivation is associated with high mortality rates in hematopoietic stem cell transplantation (HSCT) and prophylactic lamivudine (LMV) treatment is suggested to prevent this phenomenon. However, the duration of LMV treatment in HSCT patients is not fully defined and the time of immune recovery is considered the best parameter for a drug to be safely interrupted. In patients undergoing allogeneic HSCT, the time of immune recovery is not easy to define and may take years after transplantation and prolonged LMV treatments, which can lead to drug-resistant viral strains. An anti-HBc-positive hematological patient who was undergoing prolonged immunosuppression and who experienced HBV reactivation 3 months after the suspension of a prolonged LMV prophylaxis is described. HBV-DNA matching an atypical serological profile characterized by HbsAg negativity and anti-HBs positivity was detected in the patient. The genotypic analysis of the HBV strain identified T127P, F170FL and S204R mutations of HbsAg, which can hinder HBsAg recognition in a diagnostic assay. HBV reactivation in the HSCT host can be sustained by HBsAg viral variants with characteristics of altered immunogenicity that cannot be detected by usual laboratory tests. This clinical case description suggests the importance of screening for serum HBV-DNA levels in the diagnosis of HBV reactivation and monitoring HBV-DNA after prophylaxis suspension, particularly in HSCT subjects who have undergone prolonged periods of LMV treatment.

  6. Epidemiological characteristics of the carriers with coexistence of HBsAg and anti-HBs based on a community cohort study.

    Science.gov (United States)

    Pu, Z; Li, D; Wang, A; Su, H; Shao, Z; Zhang, J; Ji, Z; Gao, J; Choi, B C K; Yan, Y

    2016-04-01

    The coexistence of HBsAg and anti-HBs is an atypical serological pattern in HBV infection. There is no epidemiological characteristics of this serological pattern in the community and there is controversy over the molecular mechanisms underlying this pattern. We investigated the epidemiological characteristics of the carriers with HBsAg and anti-HBs in a longitudinal community cohort study. The prevalence of this atypical serological pattern was 2.93% (122/4169) in HBsAg-positive populations. The prevalence progressively increased with age from 40 to 70 years old. The rate of HBeAg positive and detectable HBV DNA were both significantly higher in carriers with this pattern than in carriers who were HBsAg positive but anti-HBs negative (26/122 verse 598/4047, P = 0.046; 86/122 verse 275/529,P coexistence HBsAg and anti-HBs, 14.81% of the carriers lost their anti-HBs. Viral sequencing showed that carriers with coexistence of HBsAg and anti-HBs had higher numbers of residue changes within the S gene than carriers who were HBsAg positive but anti-HBs negative (2.42 verse 1.33 changes per 100 residues, P coexistence of HBsAg and anti-HBs is a unique serological pattern which may be associated with an increased risk of adverse clinical outcome and may be related to HBsAg immune variants which have genotypic heterogeneity. © 2015 John Wiley & Sons Ltd.

  7. Immunomodulatory effects of HBsAg vaccine and levamisole in chronic hepatitis B and hepatitis B carrier children.

    Science.gov (United States)

    Demirci, Fikret; Bayraktaroğlu, Ziya; Karaoğlan, Murat; Coşkun, Yavuz; Karaoğlan, Ilkay; Okan, Vahap

    2005-12-01

    Pathogenesis of chronic hepatitis B and hepatitis B carrier status is related to deficiencies in the immune system. Thus, treatments regulating the immune system are under discussion. The aim of this study was to investigate the effects of HBsAg vaccine and levamisole on lymphocyte subgroups and immunoglobulins in children with chronic hepatitis B and hepatitis B carriers. A total of 93 naive children (43 chronic hepatitis B carriers, 50 chronic hepatitis B patients) were treated in three groups with HBsAg vaccine, levamisole or levamisole plus HBsAg vaccine. Levamisole (ketrax) was delivered as 2.5 mg/kg/day per os, three times per week for three months; the vaccine (Gen HevacB) was administered subcutaneously as 20, 30, 40 microg at one-month intervals. Both medications were delivered at same dosages in the combined group. The examinations were performed at pre-treatment and at the end of the third month when the treatment concluded. After treatments, CD3, CD4 and CD4/CD8 significantly increased and CD8 significantly decreased in chronic hepatitis B patient groups, except in the levamisole treated group. IgG and IgA were significantly decreased in all groups of chronic hepatitis B patients. It was found that HBsAg vaccine induced cellular immunostimulation in children with chronic hepatitis B; however, levamisole did not. The immune cells of hepatitis B carriers did not manifest a significant change in any treatment group. Although there was no change in B-cell, significant decreases were determined in immunoglobulins (IgG, IgA), especially in chronic hepatitis B patients.

  8. A pilot external quality assurance study of transfusion screening for HIV, HCV and HBsAG in 12 African countries.

    Science.gov (United States)

    Bloch, E M; Shah, A; Kaidarova, Z; Laperche, S; Lefrere, J-J; van Hasselt, J; Zacharias, P; Murphy, E L

    2014-11-01

    Serologic screening for the major transfusion transmissible viruses (TTV) is critical to blood safety and has been widely implemented. However, actual performance as measured by proficiency testing has not been well studied in sub-Saharan Africa. Therefore, we conducted an external quality assessment of laboratories engaged in transfusion screening in the region. Blinded test panels, each comprising 25 serum samples that were pedigreed for HIV, HBsAg, HCV and negative status, were sent to participating laboratories. The panels were tested using the laboratories' routine donor screening methods and conditions. Sensitivity and specificity were calculated, and multivariable analysis was used to compare performance against mode of testing, country and infrastructure. A total of 12 African countries and 44 laboratories participated in the study. The mean (range) sensitivities for HIV, HBsAg and HCV were 91·9% (14·3-100), 86·7% (42·9-100) and 90·1% (50-100), respectively. Mean specificities for HIV, HBsAg and HCV were 97·7%, 97% and 99·5%, respectively. After adjusting for country and infrastructure, rapid tests had significantly lower sensitivity than enzyme immunoassays for both HBsAg (P < 0·0001) and HCV (P < 0·05). Sensitivity also varied by country and selected infrastructure variables. While specificity was high, sensitivity was more variable and deficient in a substantial number of testing laboratories. These findings underscore the importance of proficiency testing and quality control, particularly in Africa where TTV prevalence is high. © 2014 International Society of Blood Transfusion.

  9.  Active-passive Immunization Effectiveness Against Hepatitis B Virus in Children Born to HBsAg Positive Mothers in Amol, North of Iran

    Directory of Open Access Journals (Sweden)

    2011-11-01

    Full Text Available  Objectives: HBV infection is a contagious disease that may transmit vertically from mothers to their neonates or horizontally by blood products and body secretions. Over 50�0of Iranian carriers have contracted the infection perinatally, making this the most likely route of transmission of HBV in Iran. This study assesses the serologic markers of HBV in children born to HBsAg positive mothers who received HBIG and 3 doses of HBV vaccine. Methods: To evaluate the effectiveness of vaccination against HBV, a study was conducted on 95 Children, born to hepatitis B surface antigen (HBsAg-positive mothers, who had received Hepatitis B Immune Globulin and HBV vaccines during 2004-2008. All children were tested for the presence of HBsAg, anti-HBs and anti-HB core antigen (anti-HBc. Results: Among an estimated 30000 pregnant women during the five year study, about 130 (0.42�20were HBV carriers. Ninety-five children from these mothers were enrolled in this study. Only one child (1.1�20was HBsAg positive, while 88.4�0of children were Anti-HBs Positive. Eleven children (11.6�20were exposed to HBV as shown by the presence of anti-HBc. A significant difference was observed between the children’s age and Anti-HBs (p=0.0001. Conclusion: Passive-active immunoprophylaxis of high risk babies was highly efficacious in preventing perinatal transmission of the HBV carrier state. Also, evaluation of serologic markers in HBV infected people is important for designing the strategies for disease control.

  10. HBV reactivation with fatal fulminating hepatitis during rituximab treatment in a subject negative for HBsAg and positive for HBsAb and HBcAb.

    Science.gov (United States)

    Sarrecchia, Cesare; Cappelli, Alessandra; Aiello, Pasquale

    2005-08-01

    A 51-year-old man who was hepatitis B surface antigen (HBsAg)-negative and positive for anti-hepatitis B surface antigen (anti-HBs) and anti-hepatitis B core antigen (anti-HBc), during rituximab therapy for chronic Lymphocytic leukemia, developed reactivation of hepatitis B virus (HBV) infection with hepatitis that proceeded towards hepatic failure and death in spite of lamivudine therapy. HBsAg remained persistently negative, notwithstanding a high HBV-DNA titer. Our observation, following other cases of fatal reactivation of HBV infection in patients receiving rituximab, suggests that, in all patients with previous markers of HBV infection, lamivudine prophylaxis should be considered during rituximab therapy.

  11. Correlation between HBsAg, prothrombin time activity, and indocyanine green retention rate at 15 minutes in patients with HBeAg-positive chronic HBV infection

    Directory of Open Access Journals (Sweden)

    FAN Wenhai

    2016-11-01

    Full Text Available ObjectiveTo investigate the correlation between HBsAg, prothrombin time activity (PTA, and indocyanine green retention rate at 15 minutes (ICG R15 in patients with HBeAg-positive chronic HBV infection. MethodsA total of 92 patients with HBeAg-positive chronic HBV infection who were admitted to The First Hospital of Lanzhou University from December 2015 to April 2016 were enrolled and divided into chronic hepatitis B (CHB group (24 patients, compensated liver cirrhosis group (38 patients, and decompensated liver cirrhosis group (30 patients. Serum HBsAg quantitation, PTA test, and liver reserve function test (ICG R15 were performed for all patients. The chi-square test was used for comparison of categorical data between groups, an analysis of variance was used for comparison of continuous data between multiple groups, and a Pearson correlation analysis was also performed. ResultsThere were significant differences between the three groups in serum HBsAg quantitation (3.82±0.43 log10IU/ml vs 2.88±0.36 log10IU/ml vs 2.60±0.27 log10IU/ml, F=25.19, P<0.001, ICG R15 (7.51%±3.10% vs 9.57%±8.18% vs 24.13%±14.28%, F=24.00, P=0.001, and PTA (8100%±1762% vs 83.08%±9.64% vs 62.32%±16.90%, F=13.42, P=0.009. The correlation analysis showed that PTA was negatively correlated with ICG R15 in all three groups (r=-0.948, -0.602, and -0.735, all P<0.01. In the compensated liver cirrhosis group and decompensated liver cirrhosis group, HBsAg was positively correlated with PTA (r=0.410 and 0.473, both P<0.05 and negatively correlated with ICG R15 (r=-0.427 and -0.768, P<0.01. ConclusionIn HBeAg positive patients, there are certain correlations between HBsAg, PTA, and ICG R15, which, to a certain degree, reflects the liver reserve function in patients with chronic HBV infection.

  12. Immune responses to HBsAg conjugated to protein D of non-typeable Haemophilus influenzae in mice.

    Directory of Open Access Journals (Sweden)

    Qiudong Su

    Full Text Available Hepatitis B vaccine that contains an aluminum hydroxide adjuvant induces apoptotic death of Hepa 1-6 cells. Difficult-to-degrade chemical additives in vaccines effectively enhance vaccine immunogenicity, but also affect the host tissue. Identification of bio-molecules that are readily degraded and compatible in vivo as an adjuvant is important for vaccine research. The hapten-carrier effect suggests that stimulation of helper T (Th cells by carrier adjuvants is feasible. Protein D (PD of non-typeable Haemophilus influenzae covalently conjugated to some polysaccharide vaccines has been confirmed to convert T-cell independent (TI antigens into T-cell dependent (TD antigens, and elicit strong T-cell responses ultimately. Herein, we would substitube PD for aluminum hydroxide adjuvant in Hepatitis B vaccine.Truncated PD (amino acids 20-364 was expressed in Escherichia coli and purified by (NH42SO4 precipitation and DEAE chromatography. After evaluation of antigenicity by western blotting, PD was covalently conjugated to yeast-derived recombinant HBsAg by cross-linking with glutaraldehyde. Intramuscular immunization with the conjugate induced higher level of HBsAg-specific antibody than did HBsAg alone (p < 0.05, and was comparable to commercial Hepatitis B vaccine. During the surveillance period (days 35-105, anti-HBs titers were hold high. Moreover, the conjugated vaccine enhanced Th1 immune responses, while Th2 responses were also activated and induced an antibody response, as determined by IFN-γ ELISPOT and IgG1/IgG2a ratio assays.Recombinant truncated PD covalently conjugated to HBsAg antigen enhanced the immunogenicity of the antigen in mice simultaneously by humoral and cellular immune response, which would facilitate therapeutic hepatitis B vaccines.

  13. Potential infectivity of blood from HBsAG asymptomatic carriers due to the presence of HBV-DNA and comparison with other markers of hbv infection Potencial de infectividade em sangue de portadores assintomáticos de HBsAg caracterizado pela presença de HBV-DNA e comparação com outros marcadores da Hepatite B.

    Directory of Open Access Journals (Sweden)

    M. Valeria Tedeschi

    1989-12-01

    Full Text Available Serum samples from 356 HBsAg positive asymptomatic carriers, which were titrated by reverse passive hemagglutination, were analysed for the presence of HBV-DNA, HBsAg and IgM anti-HBc. The samples were divided in three classes, according to the titers of HBsAg and IgM anti-HBc and the distribution of HBV-DNA and HBsAg among these classes was studied. In the high titer class of HBsAg, 65% of samples have one or both markers against only 19% in the low titer class. From the total of 356 samples, 121 gave positive results for IgM anti-HBc (33.9%. From these, 38.9% of HBV-DNA and 47.9% of HBeAg were observed, whereas in samples with absence of IgM anti-HBc, 18.3% and 16.6% were respectively found. A higher frequency of agreement between all these markers was found in the class of high titers of HBsAg; however, HBV-DNA was detected in the low titer class of HBsAg and little or no IgM anti-HBc, showing potential blood infectivity even in HBsAg positive borderline samples.Em 356 soros HBsAg positivos de portadores assintomáticos, titulados por hemaglutinação passiva reversa, foi analisada a presença de HBV DNA, HBeAg e IgM anti-HBc, da seguinte forma: as amostras foram divididas em três classes de acordo com o título de HBsAg e IgM anti-HBc e foi verificada a distribuição de HBV DNA e HBsAg nestas classes. Em amostras com títulos elevados de HBsAg, 65% das amostras tiveram um ou ambos os marcadores HBV-DNA e HBsAg e as mesmas foram encontradas em apenas 19% das amostras com baixo título de HBsAg. Do total de 356 amostras, 121 foram positivas para IgM anti-HBc (33.9%. Destas, 38.9% de HBV-DNA e 47.9% de HBeAg foram observadas, ao passo que em amostras com ausência de IgM anti-HBc, 18.3% e 16.6% foram respectivamente encontrados. A concordância entre os três marcadores foi encontrada em. amostras com alto título de HBsAg, entretanto HBV-DNA foi também detectado em grupo de baixo título de HBsAg na ausência de IgM anti-HBc ou em n

  14. Human immunodeficiency virus (HIV) seropositivity and hepatitis B surface antigenemia (HBSAG) among blood donors in Benin city, Edo state, Nigeria.

    Science.gov (United States)

    Umolu, Patience Idia; Okoror, Lawrence Ehis; Orhue, Philip

    2005-03-01

    Human Immunodeficiency Virus and Hepatitis B virus are blood borne pathogens that can be transmitted through blood transfusion and could pose a huge problem in areas where mechanisms of ensuring blood safety are suspect. This study became necessary in a population where most of the blood for transfusion is from commercial blood donors. A total of 130 donors comprising 120 commercial donors and 10 voluntary donors were tested for antibodies to human immunodeficiency virus and hepatitis B surface antigen in Benin city using Immunocomb HIV - 1 and 2 Biospot kit and Quimica Clinica Aplicada direct latex agglutination method respectively. Thirteen (10%) samples were HIV seropositive and 7(5.8%) were HBsAg positive. The age bracket 18 - 25years had the highest numbers of donors and also had the highest number of HBsAg positive cases (7.8%) while the age group 29 - 38years had highest number of HIV seropositive cases. High prevalence of HIV antibodies and Hepatitis B surface antigen was found among commercial blood donors. Appropriate and compulsory screening of blood donors using sensitive methods, must be ensured to prevent post transfusion hepatitis and HIV.

  15. Predicting response to HBV vaccination in people with positive anti-HBc but negative HBsAg and anti-HBs.

    Science.gov (United States)

    Kabir, Ali; Keshvari, Maryam; Kashani, Amir Hossein Faghihi; Alavian, Seyed-Moayed

    2008-01-01

    There are 5.1-6.5% of people with positive anti-HBc in Iran. The aim of this study was to assess the predicting factors of response to hepatitis B vaccination in anti-HBc positive subjects. Total response rate to vaccination was 79.8% (75 cases) and 67.9% (38 cases) in cases and controls, respectively. Nineteen persons (20.2%) in cases and 18 persons (32.1%) of controls had negative anti-HBs even after three doses of HB vaccination. Factor associated with decreased response to vaccination was prior history of being HBsAg positive (OR = 1.3, p = 0.01). In a quasi-experimental study, 94 people with negative HBsAg, negative anti-HBs and positive anti-HBc (cases) and 56 persons with negative HBsAg, anti-HBs and anti-HBc (controls) were vaccinated at zero, one and six months with recombinant hepatitis B vaccine. Successful immunization was defined by anti-HBs antibody titer > or =10 mIU/mL. The rate of response to hepatitis B vaccination is nearly like other studies but somewhat different. Higher percent of married cases together with higher percent of positive HBsAg in spouses may explain the slight difference in the response to vaccination in cases in comparison with controls as a result of booster like effect that seldom happens because of recurrent contacts between the subjects and the HBsAg positive spouses spontaneously.

  16. [Relationship between HBeAg from HBsAg positive mothers and regulatory T cells in neonates and its influence on HBV intrauterine transmission].

    Science.gov (United States)

    Hao, H Y; Yang, Z Q; Xu, X X; Wang, X F; Wang, B; Shi, X H; Fu, Z D; Wang, B; Wang, S P

    2017-10-10

    Objective: To explore the relationship between HBeAg in HBsAg positive mothers and CD(4)(+)CD(25)(+) Foxp3 (+)regulatory T cells (Treg) in newborns, as well as how they would influence the increasing risk on HBV intrauterine transmission. Methods: We collected information on general demographic characteristics and delivery on 270 HBsAg positive mothers and their newborns from the Third People's Hospital of Taiyuan. Fluorescence quantitative polymerase chain reaction (FQ-PCR) and chemiluminescence immunoassay (CLIA) were used to detect HBV DNA and HBV serological markers in peripheral blood from both mothers and neonates. The expression of Treg and other immune cells in peripheral blood of neonates were detected with flow cytometry (FCM). Results: Maternal HBeAg positive rates were associated with an increased risk of intrauterine transmission ( OR =4.08, 95 %CI : 1.89-8.82). Rates of Treg in newborns born to HBsAg-positive mothers were higher than that of the negative group ( Z =2.29, P =0.022). Each pair of the subjects was assigned to five different groups according to the HBeAg titers of mothers. Frequencies of both Treg and HBeAg in newborns and HBV DNA in mothers between the above said 5 groups showed similar trends of changing patterns and the differences between groups were statistically significant(χ(2)=18.73, P HBV DNA, mother's HBeAg titers were positively related to the percentage of Treg in their newborns ( r(s) =0.19, P =0.039). In addition, the frequencies of Treg were negatively correlated with pDC and CD(4)(+) T cell in their newborns ( r(s) =-0.21, P =0.017; r(s) =-0.23, P =0.009). Conclusion: HBeAg from HBsAg positive mothers might have inhibited the function of neonatal DC cells and T cells to reduce the immune response to HBV by up-regulating the proportion of Treg and finally increased the risk of HBV intrauterine transmission.

  17. Seroprevalence of Hepatitis B Surface Antigen (HBsAg) among ...

    African Journals Online (AJOL)

    Globally, Hepatitis B Virus has been identified as one of the most common infectious diseases and a major public health problem.This study was therefore carried out to assess the prevalence of Hepatitis B virus infection among primary school children attending LGE primary school, Sabon Pegi, Kuru, Nigeria.

  18. Construction and immunological evaluation of truncated hepatitis B core particles carrying HBsAg amino acids 119–152 in the major immunodominant region (MIR)

    Energy Technology Data Exchange (ETDEWEB)

    Su, Qiudong; Yi, Yao [National Institute for Viral Disease Control and Prevention, China Center for Disease Control and Prevention, Changbai Road 155, Changping District, Beijing 102206 (China); Guo, Minzhuo [Beijing Entry-Exit Inspection and Quarantine Beureau, Tianshuiyuan Lane 6, Chaoyang District, Beijing 100026 (China); Qiu, Feng; Jia, Zhiyuan; Lu, Xuexin; Meng, Qingling [National Institute for Viral Disease Control and Prevention, China Center for Disease Control and Prevention, Changbai Road 155, Changping District, Beijing 102206 (China); Bi, Shengli, E-mail: shengli_bi@163.com [National Institute for Viral Disease Control and Prevention, China Center for Disease Control and Prevention, Changbai Road 155, Changping District, Beijing 102206 (China)

    2013-09-13

    Highlights: •The conformational HBV neutralization antigen domain was successfully displayed on the surface of truncated HBc particles. •Appropriate dialysis procedures to support the renaturing environment for the protein refolding. •Efficient purification procedures to obtain high purity and icosahedral particles of mosaic HBV antigen. •Strong immune responses not only including neutralization antibody response but also Th1 cell response were induced in mice. -- Abstract: Hepatitis B capsid protein expressed in Escherichia coli can reassemble into icosahedral particles, which could strongly enhance the immunogenicity of foreign epitopes, especially those inserted into its major immunodominant region. Herein, we inserted the entire ‘α’ antigenic determinant amino acids (aa) 119–152 of HBsAg into the truncated HBc (aa 1–144), between Asp{sup 78} and Pro{sup 79}. Prokaryotic expression showed that the mosaic HBc was mainly in the form of inclusion bodies. After denaturation with urea, it was dialyzed progressively for protein renaturation. We observed that before and after renaturation, mosaic HBc was antigenic as determined by HBsAg ELISA and a lot of viruslike particles were observed after renaturation. Thus, we further purified the mosaic viruslike particles by (NH{sub 4}){sub 2}SO{sub 4} precipitation, DEAE chromatography, and Sepharose 4FF chromatography. Negative staining electron microscopy demonstrated the morphology of the viruslike particles. Immunization of Balb/c mice with mosaic particles induced the production of anti-HBs antibody and Th1 cell immune response supported by ELISPOT and CD4/CD8 proportions assay. In conclusion, we constructed mosaic hepatitis core particles displaying the entire ‘α’ antigenic determinant on the surface and laid a foundation for researching therapeutic hepatits B vaccines.

  19. Detection of HbsAg and hATIII genetically modified goats (Caprahircus) by loop-mediated isothermal amplification.

    Science.gov (United States)

    Tao, Chenyu; Zhang, Qingde; Zhai, Shanli; Liu, Bang

    2013-11-01

    In this study, sensitive and rapid detection systems were designed using a loop-mediated isothermal amplification (LAMP) method to detect the genetically modified goats. A set of 4 primers were designed for each exogenous nucleic acids HBsAg and hATIII. The DNA samples were first amplified with the outer and inner primers and released a single-stranded DNA,of which both ends were stem-loop structure. Then one inner primer hybridized with the loop, and initiated displacement synthesis in less than 1 h. The result could be visualized by both agarose gel electrophoresis and unaided eyes directly after adding SYBR GREEN 1. The detection limit of LAMP was ten copies of target molecules, indicating that LAMP was tenfold more sensitive than the classical PCR. Furthermore, all the samples of genetically modified goats were tested positively by LAMP, and the results demonstrated that the LAMP was a rapid and sensitive method for detecting the genetically modified organism.

  20. Lack of immune potentiation by complexing HBsAg in a heat-inactivated hepatitis B vaccine with antibody in hepatitis B immunoglobulin

    NARCIS (Netherlands)

    Lelie, P. N.; van Amelsfoort, P. J.; Martine de Groot, C. S.; Bakker, E.; Schaasberg, W.; Niessen, J. C.; Reesink, H. W.

    1989-01-01

    In a randomized, dose-response study among 305 health care workers, we examined whether the immunogenicity of a heat-inactivated hepatitis B vaccine could be enhanced when HBsAg was complexed by anti-HBs contained in hepatitis B immunoglobulin either at equivalent proportions or at 10-fold antigen

  1. Serologic tracers (HBsAg and HBsAc) of hepatitis B virus in expectant mothers of the Perinatal Maternal Institute

    CERN Document Server

    Garcia, B M

    1997-01-01

    A study on hepatitis B tracers, (HBsAg and HBsAc), was conducted in women with different months of pregnancy at the Perinatal Maternal Institute in Lima, Peru. A total of 1010 mothers were studied during the period of January to October 1996, establishing by radioimmunoassay (RIA) whether they were positive or not. The results showed a prevalence rate of 1,6 for HBsAc and 1,3 for HBsAg for every 100,000 inhabitants. The incidence rate was 0,332 for HBsAc and 0,07 for HBsAg for every 100,000 inhabitants. This means that 21 expectant mothers are HBsAc positive and 5 are HBsAg positive. According to the investigations, there were different ways of transmission; promiscuity must be highlighted, as well as age -most of the mothers who were positive were between 20 and 25 years old- and origin. Most of them were immigrants from different places and live in shantytowns, which indicates that most of them have limited economic resources and have not received any orientation on family planning.

  2. Serologic tracers (HBsAg and HBsAc) of hepatitis B virus in expectant mothers of the Perinatal Maternal Institute

    International Nuclear Information System (INIS)

    Garcia G, B.M.

    1997-01-01

    A study on hepatitis B tracers, (HBsAg and HBsAc), was conducted in women with different months of pregnancy at the Perinatal Maternal Institute in Lima, Peru. A total of 1010 mothers were studied during the period of January to October 1996, establishing by radioimmunoassay (RIA) whether they were positive or not. The results showed a prevalence rate of 1,6 for HBsAc and 1,3 for HBsAg for every 100,000 inhabitants. The incidence rate was 0,332 for HBsAc and 0,07 for HBsAg for every 100,000 inhabitants. This means that 21 expectant mothers are HBsAc positive and 5 are HBsAg positive. According to the investigations, there were different ways of transmission; promiscuity must be highlighted, as well as age -most of the mothers who were positive were between 20 and 25 years old- and origin. Most of them were immigrants from different places and live in shantytowns, which indicates that most of them have limited economic resources and have not received any orientation on family planning

  3. [Retrospective evaluation of HBsAg, anti-HCV, anti-HIV and syphilis reagin antibody seropositivity in blood donors at the Trabzon Farabi Hospital].

    Science.gov (United States)

    Aydin, Faruk; Cubukçu, Kivanç; Yetişkul, Serpil; Yazici, Yelda; Kaklikkaya, Neşe

    2002-01-01

    Transfusion of blood and blood products is a widely used method for therapy in medicine, however it may result with the transmission of infectious agents from donor to recipient. In order to achieve safe blood transfusions and to minimize post-transfusion infections, several screening tests for infectious agents are routinely done all around the world as well as in our country. In this study, HBsAg, anti-HCV, anti-HIV and syphilis reagin antibody tests results have been retrospectively evaluated for 33.766 blood donors during January 1, 1997 to December 31, 2000 in Blood Center of Farabi Hospital, Black Sea Technical University. Testing for HBsAg, anti-HIV and anti-HCV has been done by using commercially available micro and/or macro enzyme immunoassays, and syphilis reagin antibody test by latex agglutination (RPR) method. The indeterminate results were confirmed by retesting of sera with microparticle enzyme immunoassay and Western blot methods. As a result, in 1331 (3.94%) subjects HBsAg, in 250 (0.74%) subjects anti-HCV, and in 161 (0.47%) subjects RPR were found positive. Twenty samples which have had the results in gray-zone for anti-HIV, have been found negative with the confirmation tests.

  4. Seroprevalence of HBsAg and its risk factors among pregnant ...

    African Journals Online (AJOL)

    Yemane Berhane

    The questionnaire included level of education, occupation, income, ethnicity, and history of dental and surgical procedure, tattooing, exposures to unsafe injection, history of caesarian section, abortion, liver disease, blood transfusion and ear piercing in jewelers shop. II. Serological detection of Hepatitis B surface antigen.

  5. Detection of S-gene 'a' determinant variants in hepatitis B patients with both positive HBsAg and HBsAb markers

    International Nuclear Information System (INIS)

    Wu Yueping; Ling Yongwu; Huang Songping; Wang Shipeng; Chen Yufeng; Mao Liping; Lu Jianrong

    2005-01-01

    Objective: To explore the S-gene 'a' determinant variants in hepatitis B patients with both positive HBsAg and HBsAb markers and the effect on the antigenicity of HBsAg. Methods: Quantitative determination of HBV - DNA with competent PCR microfluidic chit method was performed in eight sera specimens from seven hepatitis B patients with both positive HBsAg and HBsAb markers. HBV S-gene was amplified with nested PCR, the PCR product was directly examined for any sequence variant of the amino acids. HBV markers were tested with the very sensitive ELISA/MEIA method in these seven patients. The above rests were also performed in 15 children after failed immunization with hepatitis B vaccine and 9 recipients of liver transplantation for terminal hepatitis B treated with HBIG and lamivudine, serving as controls. Results: The HBsAb contents in the seven patients were all below 80 mIu/ml. Two of the patients with positive HBV-DNA showed no 'a' determinant variant. Two of the four HBV-DNA negative patients demonstrated amino-acid variants (126, 131). One patients who was originally HBV-DNA positive but later turned negative after treatment with interferon and lamivudine demonstrated variant (126). In the 9 patients after successful liver transplantation, the HBsAb contents were all about 150mIu/ml with negative HBV-DNA and no variant. In the 15 immunization failures, HBV-DNA was positive in 14 of them, with 2 cases of variant at 145, 1 case at 126 and 1 case at 134. Conclusion: In some patients with chronic B hepatitis with both positive HBsAg and HBsAb markers, as well as in some vaccine immunization failures, there were 'a' determinant variants, which might alter the antigenicity of HBsAg with escape from the neutralization of low HBsAb. The 'a' determinant variant might also affect the replication of the virus. In this study, no variant was shown in patients after successful liver transplantation. However, the number of patients was too small and the result was of no

  6. Infección oculta por el virus de la hepatitis B en hijos de madres positivas al HBsAg

    Directory of Open Access Journals (Sweden)

    Marité Bello-Corredor

    2016-04-01

    Full Text Available La infección oculta por el virus de la hepatitis B (IOB, se caracteriza por la presencia en suero o plasma del genoma viral (ADN-VHB y anticuerpos contra la proteína de la cápside (anti-HBc en ausencia del antígeno de superficie (HBsAg, marcador que tradicionalmente se emplea para identificar la presencia del virus. Con el objetivo de caracterizar la presencia de IOB en hijos de madres positivas al HBsAg, se estudiaron 291 muestras séricas de niños con la condición de ser HBsAg (- y anticuerpos anti-HBsAg (anti-HBs menores de 50 UI/L, conservadas en la seroteca del Laboratorio de Referencia Nacional de Hepatitis Virales. Se realizaron ensayos para determinar la exposición al virus (anti-HBc, a los sueros anti-HBc (+ se les realizó Reacción en Cadena de la Polimerasa en Tiempo Real (RCP-TR para determinar y cuantificar el ADN-VHB. La prevalencia de exposición al VHB (anti-HBc fue 16,8% (49/291. El ADN viral se cuantificó en el 14% (6/43 de los casos anti-HBc (+, observándose cargas virales que oscilaban entre 2,15 x 101 hasta 3,42 x 101 UI/mL. La prevalencia de la IOB para el total de los pacientes analizados fue 2,1% (6/291, considerada relativamente baja. No se encontró asociación significativa entre las variables sociodemográficas analizadas tales como: edad, sexo y provincia de procedencia. La IOB está presente en hijos de madres positivas al HBsAg, a pesar de la profilaxis contra la hepatitis B. Por lo tanto, se requiere de pesquisajes adecuados para detectar dicha entidad. Las implicaciones clínicas y epidemiológicas de la misma, requieren de un estrecho monitoreo y atención de estos pacientes. Este estudio se realiza por primera vez en Cuba y aporta conocimientos útiles para el diagnóstico, prevención y control de esta enfermedad en niños.

  7. A meta-analysis of the antiviral activity of the HBV-specific immunotherapeutic TG1050 confirms its value over a wide range of HBsAg levels in a persistent HBV pre-clinical model.

    Science.gov (United States)

    Kratzer, Roland; Sansas, Benoît; Lélu, Karine; Evlachev, Alexei; Schmitt, Doris; Silvestre, Nathalie; Inchauspé, Geneviève; Martin, Perrine

    2018-02-01

    Pre-clinical models mimicking persistent hepatitis B virus (HBV) expression are seldom, do not capture all features of a human chronic infection and due to their complexity, are subject to variability. We report a meta-analysis of seven experiments performed with TG1050, an HBV-targeted immunotherapeutic, 1 in an HBV-persistent mouse model based on the transduction of mice by an adeno-associated virus coding for an infectious HBV genome (AAV-HBV). To mimic the clinical diversity seen in HBV chronically infected patients, AAV-HBV transduced mice displaying variable HBsAg levels were treated with TG1050. Overall mean percentages of responder mice, displaying decrease in important clinical parameters i.e. HBV-DNA (viremia) and HBsAg levels, were 52% and 51% in TG1050 treated mice, compared with 8% and 22%, respectively, in untreated mice. No significant impact of HBsAg level at baseline on response to TG1050 treatment was found. TG1050-treated mice displayed a significant shorter Time to Response (decline in viral parameters) with an Hazard Ratio (HR) of 8.3 for viremia and 2.6 for serum HBsAg. The mean predicted decrease for TG1050-treated mice was 0.5 log for viremia and 0.8 log for HBsAg, at the end of mice follow-up, compared to no decrease for viremia and 0.3 log HBsAg decrease for untreated mice. For mice receiving TG1050, a higher decline of circulating viremia and serum HBsAg level over time was detected by interaction term meta-analysis with a significant treatment effect (p = 0.002 and pHBV-persistent model mimicking clinical situations.

  8. Estudo da soroprevalência do AgHBs em gestantes da 15ª Regional de Saúde e da imunoprofilaxia para os recém-nascidos das gestantes AgHBs positivo = Study into the HBsAg seroprevalence in pregnant women from the 15th Health Regional and the immunoprophylaxia on the newborns of these HBsAg-positive women

    Directory of Open Access Journals (Sweden)

    Sonia Kaori Miyamoto

    2008-01-01

    Full Text Available Determinar a prevalência do AgHBs nas gestantes da 15ª Regional de Saúde (15ª R.S. atendidas no Laboratório de Ensino e Pesquisa em Análises Clínicas (Lepac, Universidade Estadual de Maringá, e verificar se foi solicitada a imunoprofilaxia para hepatite B aos recém-natos das gestantes AgHBs positivo, no período de janeiro de 1998 a dezembro de 2002. A pesquisa do AgHBs foi realizada pela técnica imunoenzimática IMxHBsAg e Axsym HBsAg (Laboratório Abbott. As solicitações de imunobiológicos especiais para a imunoprofilaxia da hepatite B ao CRIE foram obtidas na Seção de Epidemiologia da 15ª R.S. Foram analisadas 12.274 gestantes e a prevalência do AgHBs foide 1,0%. Dentre as 125 gestantes AgHBs positivo, foram solicitadas imunoprofilaxia para 32 (25,6% recém-nascidos. Ainda que a prevalência encontrada indique ser esta uma área de baixa endemicidade, os resultados reafirmam a importância da realização do diagnóstico da hepatite B no atendimento pré-natal, para adoção da imunoprofilaxia no recém-nascido.To determine HBsAg prevalence among pregnant women from the 15th Health Regional assisted in the Laboratório de Ensino e Pesquisa em Análises Clínicas (Lepac, Universidade Estadual de Maringá, and verify whether immunoprophylaxis with vaccine and immunoglobulin was requested for the newborns of HBsAg-positive women during the period from January 1998 to December 2002. The research about HBsAg was conducted using the immunoenzymatic IMxHBsAg (Abbot Lab and Axsym HBsAg (Abbot Lab techniques. The requests to the CRIE for specialimmunobiologic agents for Hepatitis B immunoprophylaxis were obtained in the Department of Epidemiology from the 15th Health Regional. The analysis includes 12,274 pregnant women, and the HBsAg prevalence was 1.0%. Among 125 HBsAg positive pregnant women, immunoprophylaxis was requested for 32 (25.6% newborns. Although the prevalence detected demonstrates this to be a low endemic area, the

  9. ADCC-Mediated CD56dim NK Cell Responses Are Associated with Early HBsAg Clearance in Acute HBV Infection

    Directory of Open Access Journals (Sweden)

    Wen-Han Yu

    2018-02-01

    Full Text Available Hepatitis B virus (HBV affects up to 400 million people worldwide and accounts for approximately one million deaths per year from liver pathologies. Current treatment regimens are effective in suppressing viremia but usually have to be taken indefinitely, warranting research into new therapeutic approaches. Acute HBV infection in adults almost universally results in resolution of viremia, with the exception of immunocompromised persons, suggesting that the immune response can functionally cure or even eradicate HBV infection. Because immunophenotypic and functional studies have implicated a role for Natural Killer (NK cells in HBV clearance during acute infection, we hypothesized that a distinct NK-cell profile exists in acute HBV infection that could provide information for the mechanism of HBV clearance. Using multivariate flow cytometry, we evaluated the expression of key activating and inhibitory receptors on NK cells, and their ability to respond to classic target cell lines. Multivariate analysis revealed selective perturbation of the CD56 dim NK-cell subset during acute infection, displaying low levels of NKp46+, NKp30+, CD160+ and CD161+ cells. Intriguingly, the CD56 dim NK-cell profile predicted time to HBV surface antigen (HBsAg clearance from the blood, and distinct NK-cell profiles predicted early (NKp30, CD94, CD161 and late clearance (KIR3DL1, CD158a, perforin, NKp46. Finally, functional analysis demonstrated that early and late clearance tracked with elevated degranulation (CD107a or IFNγ production, respectively, in response to ADCC-mediated activation. In conclusion, the cytolytic CD56dim NK-cell subset is selectively activated in acute HBV infection and displays distinct phenotypic and functional profiles associated with efficient and early control of HBV, implicating antibody-mediated cytolytic NK-cell responses in the early control and functional cure of HBV infection.

  10. ADCC-Mediated CD56DIM NK Cell Responses Are Associated with Early HBsAg Clearance in Acute HBV Infection.

    Science.gov (United States)

    Yu, Wen-Han; Cosgrove, Cormac; Berger, Christoph T; Cheney, Patrick C; Krykbaeva, Marina; Kim, Arthur Y; Lewis-Ximenez, Lia; Lauer, Georg M; Alter, Galit

    2018-01-01

    Hepatitis B virus (HBV) affects up to 400 million people worldwide and accounts for approximately one million deaths per year from liver pathologies. Current treatment regimens are effective in suppressing viremia but usually have to be taken indefinitely, warranting research into new therapeutic approaches. Acute HBV infection in adults almost universally results in resolution of viremia, with the exception of immunocompromised persons, suggesting that the immune response can functionally cure or even eradicate HBV infection. Because immunophenotypic and functional studies have implicated a role for Natural Killer (NK) cells in HBV clearance during acute infection, we hypothesized that a distinct NK-cell profile exists in acute HBV infection that could provide information for the mechanism of HBV clearance. Using multivariate flow cytometry, we evaluated the expression of key activating and inhibitory receptors on NK cells, and their ability to respond to classic target cell lines. Multivariate analysis revealed selective perturbation of the CD56 dim NK-cell subset during acute infection, displaying low levels of NKp46+, NKp30+, CD160+ and CD161+ cells. Intriguingly, the CD56 dim NK-cell profile predicted time to HBV surface antigen (HBsAg) clearance from the blood, and distinct NK-cell profiles predicted early (NKp30, CD94, CD161) and late clearance (KIR3DL1, CD158a, perforin, NKp46). Finally, functional analysis demonstrated that early and late clearance tracked with elevated degranulation (CD107a) or IFNγ production, respectively, in response to ADCC-mediated activation. The cytolytic CD56 dim NK-cell subset is selectively activated in acute HBV infection and displays distinct phenotypic and functional profiles associated with efficient and early control of HBV, implicating antibody-mediated cytolytic NK-cell responses in the early control and functional cure of HBV infection.

  11. Determinants of spontaneous surface antigen loss in hepatitis B e antigen-negative patients with a low viral load.

    Science.gov (United States)

    Tseng, Tai-Chung; Liu, Chun-Jen; Yang, Hung-Chih; Su, Tung-Hung; Wang, Chia-Chi; Chen, Chi-Ling; Kuo, Stephanie Fang-Tzu; Liu, Chen-Hua; Chen, Pei-Jer; Chen, Ding-Shinn; Kao, Jia-Horng

    2012-01-01

    Loss of hepatitis B surface antigen (HBsAg) usually indicates the cure of hepatitis B virus (HBV) infection. In spontaneous hepatitis B e antigen (HBeAg) seroconverters, lower serum HBsAg and HBV DNA levels have been shown to be associated with HBsAg loss over time. However, little is known about their impacts on HBsAg loss in HBeAg-negative patients with limited viral replication. A total of 688 HBeAg-negative patients with baseline serum HBV DNA levels loss were investigated. In a mean follow-up of 11.6 years, the average annual rate of HBsAg loss was 1.6%. Baseline HBsAg and HBV DNA levels were inversely associated with subsequent HBsAg loss. When compared to patients who had HBsAg levels >1000 IU/mL, the rates of HBsAg loss were significantly higher in patients with HBsAg levels of 100-999, 10-99, and loss was 13.2 (95% CI, 7.8-22.1) for HBsAg level loss. In HBeAg-negative patients with HBV genotype B or C infection who have HBV DNA level loss. Copyright © 2011 American Association for the Study of Liver Diseases.

  12. Artificial neural network accurately predicts hepatitis B surface antigen seroclearance.

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    Ming-Hua Zheng

    Full Text Available BACKGROUND & AIMS: Hepatitis B surface antigen (HBsAg seroclearance and seroconversion are regarded as favorable outcomes of chronic hepatitis B (CHB. This study aimed to develop artificial neural networks (ANNs that could accurately predict HBsAg seroclearance or seroconversion on the basis of available serum variables. METHODS: Data from 203 untreated, HBeAg-negative CHB patients with spontaneous HBsAg seroclearance (63 with HBsAg seroconversion, and 203 age- and sex-matched HBeAg-negative controls were analyzed. ANNs and logistic regression models (LRMs were built and tested according to HBsAg seroclearance and seroconversion. Predictive accuracy was assessed with area under the receiver operating characteristic curve (AUROC. RESULTS: Serum quantitative HBsAg (qHBsAg and HBV DNA levels, qHBsAg and HBV DNA reduction were related to HBsAg seroclearance (P<0.001 and were used for ANN/LRM-HBsAg seroclearance building, whereas, qHBsAg reduction was not associated with ANN-HBsAg seroconversion (P = 0.197 and LRM-HBsAg seroconversion was solely based on qHBsAg (P = 0.01. For HBsAg seroclearance, AUROCs of ANN were 0.96, 0.93 and 0.95 for the training, testing and genotype B subgroups respectively. They were significantly higher than those of LRM, qHBsAg and HBV DNA (all P<0.05. Although the performance of ANN-HBsAg seroconversion (AUROC 0.757 was inferior to that for HBsAg seroclearance, it tended to be better than those of LRM, qHBsAg and HBV DNA. CONCLUSIONS: ANN identifies spontaneous HBsAg seroclearance in HBeAg-negative CHB patients with better accuracy, on the basis of easily available serum data. More useful predictors for HBsAg seroconversion are still needed to be explored in the future.

  13. Changing serum levels of quantitative hepatitis B surface antigen and hepatitis B virus DNA in hepatitis B virus surface antigen carriers: A follow-up study of an elderly cohort

    Directory of Open Access Journals (Sweden)

    Yuan-Hung Kuo

    2015-02-01

    Full Text Available This study was to elucidate longitudinally quantitative changes of hepatitis B virus (HBV surface antigen (HBsAg and HBV DNA in elder HBsAg carriers in a community. Among 1002 residents screened for HBsAg in 2005, 405 responded to this follow-up study in 2010. Fifty-nine (14.6% were HBsAg carriers in 2005; HBsAg quantification and HBV DNA were measured. HBsAg quantification (cutoff 1600 IU/mL and HBV DNA (cutoff 2000 IU/mL were combined to stratify the participants between two screens. A total of 30 men and 29 women with a mean age of 63.9 ± 7.9 years were enrolled. Quantitative levels of HBsAg and HBV DNA were significantly correlated in 2005 (r = 0.509, p < 0.001 and 2010 (r = 0.777, p < 0.001. Concentrations of HBsAg (IU/mL significantly decreased from 2.2 ± 1.0 log in 2005 to 1.7 ± 1.5 log in 2010 (p < 0.001. The level of HBsAg was decreased in 48 (81.4% individuals and HBsAg was undetectable in eight (13.6%. The annual incidence of HBsAg clearance was 2.7%. These 59 HBsAg carriers in 2005 were divided into four groups: low HBsAg low HBV DNA (n = 32, high HBsAg low HBV DNA (n = 5, low HBsAg high HBV DNA (n = 12 and high HBsAg high HBV DNA (n = 10. All 32 individuals in the low HBsAg low HBV DNA group were still in that group in 2010, whereas only two of the high HBsAg high HBV DNA group became inactive. As with a younger cohort in hospital, HBsAg quantification was still well correlated with HBV DNA in elderly HBsAg carriers in the community. Lower levels of both HBsAg and HBV DNA might represent an inactive HBV infection.

  14. HBsAg and aflatoxins in sera of rural (Igbo-Ora) and urban (Ibadan) populations in Nigeria.

    Science.gov (United States)

    Olubuyide, I O; Maxwell, S M; Akinyinka, O O; Hart, C A; Neal, G E; Hendrickse, R G

    1993-12-01

    The purpose of this study was to screen for the presence of hepatitis B surface antigen and aflatoxins in the sera of 100 non-hospitalized individuals from the rural population of Igbo-Ora and 89 non-hospitalized individuals from the urban population of Ibadan, Nigeria. Hitherto, such a study as this has not been undertaken in this environment. The proportions of hepatitis B surface antigen carriage and serum 'pathologic' levels of aflatoxins were high (47-49%, 8.2-9.0% respectively) but varied very little between the two different populations sampled. These findings indicate that determined efforts should be instituted to reduce or eliminate hepatitis B virus infection and aflatoxin contamination of high risk foodstuffs from this environment.

  15. Low prevalence of hepatitis B and C among tuberculosis patients in Duhok Province, Kurdistan: Are HBsAg and anti-HCV prerequisite screening parameters in tuberculosis control program?

    Science.gov (United States)

    Merza, Muayad A; Haji, Safer M; Alsharafani, Abid Mohialdeen Hasan; Muhammed, Shivan U

    2016-09-01

    Viral hepatitis, particularly hepatitis B virus (HBV) and hepatitis C virus (HCV), infections and tuberculosis (TB) are a global public health concern. Co-infection with HBV or HCV among TB patients may potentiate the risk of hepatotoxicity induced by anti-TB drugs. Hence, the aim of this study was to identify the prevalence of HBV and HCV among TB patients included in the Duhok National Tuberculosis Program (NTP). The Duhok NTP Center is a specialized institution in Duhok City, Iraq, concerned with management and follow-up of TB patients. A cross-sectional study was conducted at the center between June 2015 and May 2016. All documented TB patients were analyzed on the basis of socio-demographic and other characteristics. Thereafter, all patients underwent screening for hepatitis B surface antigen (HBsAg), anti-HCV, and anti-HIV using enzyme-linked immunosorbent assay (ELISA). The results obtained were analyzed by entering the data in binary format into a Microsoft Excel spreadsheet. A p value of Kurdistan, the negative history of injection drug use, and adherence to universal infection-control measures, including vaccination for HBV. Both history of dental intervention and belonging to a Syrian population were independent risk factors for HBV/TB co-infection. Copyright © 2016 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.

  16. Higher lifetime chance of spontaneous surface antigen loss in hepatitis B carriers with genotype C infection.

    Science.gov (United States)

    Tseng, T-C; Liu, C-J; Chen, C-L; Yang, W-T; Yang, H-C; Su, T-H; Wang, C-C; Kuo, S F-T; Liu, C-H; Chen, P-J; Chen, D-S; Kao, J-H

    2015-05-01

    Clearance of hepatitis B surface antigen (HBsAg) indicates clinical control of hepatitis B virus (HBV) infection. However, little is known about the impact of viral genomic variations on HBsAg loss. We explored the association between viral genomic factors and HBsAg loss in 2121HBeAg-negative patients. HBV pre-core stop codon (1896) and basal core promoter (BCP) (1762/1764) sequences were determined in patients with HBV DNA ≥200 IU/mL (N = 1693). The effect of HBV genotype on HBsAg loss was further validated in the whole cohort of 3445 HBsAg carriers. The cumulative lifetime (age 28-75 years) incidence of HBsAg loss was 50.4% in 2121 HBeAg-negative patients. We found that genotype C, but not pre-core stop codon or BCP mutants, was associated with HBsAg loss. Compared to genotype B patients, genotype C patients had higher lifetime chance of HBsAg loss, with hazard ratio of 1.8 (95% confidence interval: 1.4-2.4). Multivariable analysis showed that male sex, elevated ALT levels, lower serum HBV DNA and HBsAg levels, and genotype C infection were associated with higher chance of HBsAg loss independently. We then performed sensitivity analysis, which re-included HBeAg-positive, cirrhotic and treatment-experienced patients, and confirmed the robustness of our results in 3445 HBsAg carriers. Genotype C infection, compared to genotype B, is associated with a higher lifetime chance of HBsAg loss in Asian HBV carriers. © 2015 John Wiley & Sons Ltd.

  17. Low prevalence of hepatitis B and C among tuberculosis patients in Duhok Province, Kurdistan: Are HBsAg and anti-HCV prerequisite screening parameters in tuberculosis control program?

    Directory of Open Access Journals (Sweden)

    Muayad A Merza

    2016-01-01

    Full Text Available Objective/background: Viral hepatitis, particularly hepatitis B virus (HBV and hepatitis C virus (HCV, infections and tuberculosis (TB are a global public health concern. Co-infection with HBV or HCV among TB patients may potentiate the risk of hepatotoxicity induced by anti-TB drugs. Hence, the aim of this study was to identify the prevalence of HBV and HCV among TB patients included in the Duhok National Tuberculosis Program (NTP. Methods: The Duhok NTP Center is a specialized institution in Duhok City, Iraq, concerned with management and follow-up of TB patients. A cross-sectional study was conducted at the center between June 2015 and May 2016. All documented TB patients were analyzed on the basis of socio-demographic and other characteristics. Thereafter, all patients underwent screening for hepatitis B surface antigen (HBsAg, anti-HCV, and anti-HIV using enzyme-linked immunosorbent assay (ELISA. The results obtained were analyzed by entering the data in binary format into a Microsoft Excel spreadsheet. A p value of <.05 was considered to be statistically significant. Results: Two-hundred fourteen documented TB patients were recruited in this study, with 127 (59.3% males and 87 (40.7% females. The mean age of the patients was 40.34 years (±20.29. Of the total number of patients, four cases (1.8% were HBsAg-positive and one case (0.9% was positive for anti-HCV. The variables significantly associated with HBV were history of surgical dental procedure [odds ratio (OR, 0.04; 95% confidence interval (CI, −0.01 to 0.04; p = .03], and nationality (OR, 13.67; 95% CI, 0.46–210.85; p = .007. Conclusion: The prevalence of HBV and HCV co-infection among TB patients in this study was low. This may be explained by the low rate of blood transfusion among the patients, the very low prevalence of HIV infections in Kurdistan, the negative history of injection drug use, and adherence to universal infection-control measures, including vaccination for HBV

  18. Hepatitis B, C and D virus genotypes detected in HBsAg- or anti-HCV-positive people from the Republic of Moldova.

    Science.gov (United States)

    Gori, Ala; Gheorgita, Stela; Spinu, Constantin; Pinzaru, Iurie; Halacu, Ala; Sajen, Octavian; Suveica, Luminița; Sausy, Aurélie; Muller, Claude P; Hübschen, Judith M

    2018-02-01

    In the Republic of Moldova, little is known about hepatitis B, C and D virus (HBV, HCV, HDV) genotypes, although the genetic variant may influence the course and outcome of disease. For HBV genotyping, 301 hepatitis B surface antigen (HBsAg)-positive sera collected in 2010 and 2011 from drug users, prison inmates, commercial sex workers, and the general population in different geographical regions were investigated. The 31 HBsAg-positive sera collected in 2011 were also tested for HDV. Eighty-eight anti-HCV-positive sera collected between 2010 and 2011 from the general population and health care workers were used for HCV genotyping. Phylogenetic analysis of 84 HBV sequences showed that most of the viruses belonged to genotype D (n = 82, 97.6%), predominantly to the subgenotype D1/D2 cluster (n = 75/82, 91.5%). One sequence (74110) clustered as an outlier to this cluster, and six sequences belonged to subgenotype D3. Only two subgenotype A2 sequences were found. Cloning of six samples with ambiguous sequence chromatogram signals showed no mixed infections. Phylogenetic analysis of HCV sequences from 66 patients showed a predominance of subtype 1b (n = 63, 95.5%). Two sequences belonged to subtype 3a, and one to subtype 2a. HDV RNA belonging to genotype 1 was found in two sera (2/31, 6.5%). Thus, genotypes prevalent in Europe were detected for all three hepatitis viruses. For both HBV and HCV, one genotype was dominant, while occasional other variants seem to be restricted to certain cohorts and/or transmission routes.

  19. Primary immunization-like response without hepatitis following transfusion of HBeAg-positive blood

    DEFF Research Database (Denmark)

    Gluud, C; Aldershvile, J; Kryger, P

    1983-01-01

    An accidental transfusion of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) positive whole blood was given to a 19-yr-old male, bleeding after tonsillectomy. Serum obtained from the patient before the transfusion revealed no hepatitis B antigens or antibodies. After...... the transfusion the patient became HBsAg-positive, cleared this antigen and developed antibodies to both HBsAg and HBeAg. The transfusion blood was positive for total antibody and IgM antibody to hepatitis B core antigen (HBcAg). The patient's blood became positive for these antibodies after the transfusion...

  20. Prevalence of Hepatitis-B Surface Antigen among Blood Donors in ...

    African Journals Online (AJOL)

    Information is scarce on the prevalence of Hepatitis-B Virus (HBV) infection among blood donors in Taraba State. Hepatitis-B surface antigen (HBsAg) ELISA [Gudans Industrial Hong 2 Kou, China] was used to determine the prevalence of HBsAg among 804 blood donors aged between 11 and 65 years in Federal Medical ...

  1. Photoinduced formation of Ag nanoparticles on the surface of As2S3/Ag thin bilayer

    International Nuclear Information System (INIS)

    Binu, S; Khan, Pritam; Barik, A R; Sharma, Rituraj; Adarsh, K V; Golovchak, R; Jain, H

    2014-01-01

    In this article, we demonstrate the combined effect of photodoping and photoinduced-surface deposition in a bilayer of chalcogenide glass (ChG) and Ag as an alternative method to optically synthesize Ag nanoparticles (AgNP) on the surface of ChG. In our experiment, AgNP formation occurs through two distinct stages: In the first stage, Ag is transported through the As 2 S 3 layer as Ag + ions, and in the second stage Ag + ions are photo-deposited as AgNP. The ex situ x-ray photoelectron spectroscopy measurements and AFM observations show photoinduced Ag mass transport and the formation of AgNP. (paper)

  2. Prevention of the HBsAg carrier state in newborn infants of mothers who are chronic carriers of HBsAg and HBeAg by administration of hepatitis-B vaccine and hepatitis-B immunoglobulin. Double-blind randomised placebo-controlled study

    NARCIS (Netherlands)

    Wong, V. C.; Ip, H. M.; Reesink, H. W.; Lelie, P. N.; Reerink-Brongers, E. E.; Yeung, C. Y.; Ma, H. K.

    1984-01-01

    Newborn infants of Chinese HBeAg-carrier mothers in Hong Kong were randomly assigned to one of four study groups. Group I was treated with 3 micrograms heat-inactivated hepatitis B (HB) vaccine at birth and at 1, 2, and 6 months thereafter, in conjunction with seven monthly HBIg injections; group II

  3. The Lumipulse G HBsAg-Quant assay for screening and quantification of the hepatitis B surface antigen.

    Science.gov (United States)

    Yang, Ruifeng; Song, Guangjun; Guan, Wenli; Wang, Qian; Liu, Yan; Wei, Lai

    2016-02-01

    Qualitative HBsAg assay is used to screen HBV infection for decades. The utility of quantitative assay is also rejuvenated recently. We aimed to evaluate and compare the performance of a novel ultra-sensitive and quantitative assay, the Lumipulse assay, with the Architect and Elecsys assays. As screening methods, specificity was compared using 2043 consecutive clinical routine samples. As quantitative assays, precision and accuracy were assessed. Sera from 112 treatment-naïve chronic hepatitis B patients, four patients undergoing antiviral therapy and one patient with acute infection were tested to compare the correlations. Samples with concurrent HBsAg/anti-HBs were also quantified. The Lumipulse assay precisely quantified ultra-low level of HBsAg (0.004 IU/mL). It identified additional 0.98% (20/2043) clinical samples with trance amount of HBsAg. Three assays displayed excellent linear correlations irrespective of genotypes and S-gene mutations (R(2)>0.95, PLumipulse assay did not yield higher HBsAg concentrations in samples with concomitant anti-HBs. Compared with other assays, the Lumipulse assay is sensitive and specific for detecting HBsAg. The interpretation of the extremely low-level results, however, is challenging. Quantitative HBsAg results by different assays are highly correlated, but they should be interpreted interchangeably only after conversion to eliminate the biases. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Oscillatory relaxation of the Ag(110) surface

    International Nuclear Information System (INIS)

    Kuk, Y.; Feldman, L.C.

    1984-01-01

    The relaxation of the Ag(110) surface was studied by high-energy ion scattering. We find the first-layer spacing contracted by (7.8 +- 2.5)% and the second-layer spacing increased by (4.3 +- 2.5)%. The sensitivity of these results to assumptions of surface vibrations is explored. It is shown that the nearest-neighbor spacing at the surface (i.e., the spacing between the first and third layers) is contracted by (3.5 +- 0.5)%, and this result is almost independent of the surface Debye temperature. The results are consistent with the body of data indicating large, multilayer relaxation in (110)fcc surfaces

  5. Mutations in the S gene and in the overlapping reverse transcriptase region in chronic hepatitis B Chinese patients with coexistence of HBsAg and anti-HBs

    Directory of Open Access Journals (Sweden)

    Feng Ding

    2016-01-01

    Conclusions: In chronic patients, the concurrent HBsAg/anti-HBs serological profile is associated with an increased aa variability in several key areas of HBV genome. Additional research on these genetic mutants are needed to clarify their biological significance for viral persistence.

  6. Surface-enhanced Raman scattering of a Ag/oligo(phenyleneethynylene)/Ag sandwich.

    Science.gov (United States)

    Fletcher, Melissa; Alexson, D M; Prokes, Sharka; Glembocki, Orest; Vivoni, Alberto; Hosten, Charles

    2011-02-01

    α,ω-Dithiols are a useful class of compounds in molecular electronics because of their ability to easily adsorb to two metal surfaces, producing a molecular junction. We have prepared Ag nanosphere/oligo(phenyleneethynylene)/Ag sol (AgNS/OPE/Ag sol) and Ag nanowire/oligo(phenyleneethynylene)/Ag sol (AgNW/OPE/Ag sol) sandwiches to simulate the architecture of a molecular electronic device. This was achieved by self-assembly of OPE on the silver nanosurface, deprotection of the terminal sulfur, and deposition of Ag sol atop the monolayer. These sandwiches were then characterized by surface-enhanced Raman scattering (SERS) spectroscopy. The resulting spectra were compared to the bulk spectrum of the dimer and to the Ag nanosurface/OPE SERS spectra. The intensities of the SERS spectra in both systems exhibit a strong dependence on Ag deposition time and the results are also suggestive of intense interparticle coupling of the electromagnetic fields in both the AgNW/OPE/Ag and the AgNS/OPE/Ag systems. Three previously unobserved bands (1219, 1234, 2037 cm(-1)) arose in the SER spectra of the sandwiches and their presence is attributed to the strong enhancement of the electromagnetic field which is predicted from the COSMOL computational package. The 544 cm(-1) disulfide bond which is observed in the spectrum of solid OPE but is absent in the AgNS/OPE/Ag and AgNW/OPE/Ag spectra is indicative of chemisorption of OPE to the nanoparticles through oxidative dissociation of the disulfide bond. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Cationic Lipid-Formulated DNA Vaccine against Hepatitis B Virus : Immunogenicity of MIDGE-Th1 Vectors Encoding Small and Large Surface Antigen in Comparison to a Licensed Protein Vaccine

    NARCIS (Netherlands)

    Endmann, Anne; Klunder, Katharina; Kapp, Kerstin; Riede, Oliver; Oswald, Detlef; Talman, Eduard G.; Schroff, Matthias; Kleuss, Christiane; Ruiters, Marcel H. J.; Juhls, Christiane

    2014-01-01

    Currently marketed vaccines against hepatitis B virus (HBV) based on the small (S) hepatitis B surface antigen (HBsAg) fail to induce a protective immune response in about 10% of vaccinees. DNA vaccination and the inclusion of PreS1 and PreS2 domains of HBsAg have been reported to represent feasible

  8. Comparison of hepatitis B virus core-related antigen and hepatitis B surface antigen for predicting HBeAg seroconversion in chronic hepatitis B patients with pegylated interferon therapy.

    Science.gov (United States)

    Wang, Meng-Lan; Liao, Juan; Wei, Bing; Zhang, Dong-Mei; He, Ming; Tao, Ming-Chuan; Chen, En-Qiang; Tang, Hong

    2018-02-20

    Recent studies revealed that both quantitative hepatitis B surface antigen (qHBsAg) and hepatitis B core-related antigen (qHBcrAg) could serve as a good marker for predicting treatment response and indirectly reflecting intrahepatic cccDNA levels. This study aimed to compare the value of qHBsAg and qHBcrAg in predicting HBeAg seroconversion among patients undergoing PEG-IFN therapy. A total of 31 HBeAg-positive patients, who underwent PEG-IFN therapy for 12 months and follow-up for six months were retrospectively included in this study. The serum qHBsAg level was measured using Elecsys® HBsAg II Quant Assay and serum qHBcrAg level was measured using chemiluminescence enzyme immunoassay. During the 12-month treatment, the absolute levels of serum qHBsAg and qHBcrAg were both lower in patients with HBeAg seroconversion as compared to patients without HBeAg seroconversion, but only the difference in qHBcrAg was significant. During the 6-month follow-up period, both qHBsAg and qHBcrAg levels were rebounded significantly among patients without HBeAg seroconversion. Among patients with HBeAg seroconversion, no sustained significant decline of qHBsAg was observed, but serum qHBcrAg levels continued to decline significantly. The ROC curves analysis showed that both absolute qHBcrAg level and the extent of qHBcrAg decline at month 1 had better performance for the prediction of HBeAg seroconversion at month 6 after treatment, as compared to that of qHBsAg. Early on-treatment qHBcrAg may be a good biomarker for predicting off-treatment HBeAg seroconversion in patients receiving PEG-IFN therapy.

  9. Historic and current hepatitis B viral DNA and quantitative HBsAg level are not associated with cirrhosis in non-Asian women with chronic hepatitis B

    NARCIS (Netherlands)

    Harkisoen, S.; Arends, J. E.; van den Hoek, J. A. R.; Whelan, J.; van Erpecum, K. J.; Boland, G. J.; Hoepelman, A. I. M.

    2014-01-01

    Some studies done in Asian patients have shown that serum levels of hepatitis B virus (HBV) DNA predict the development of cirrhosis. However, it is unclear whether this also applies for non-Asian patients. This study investigated historic and current HBV DNA and quantitative hepatitis B surface

  10. First-principles study of surface plasmons on Ag(111) and H/Ag(111)

    DEFF Research Database (Denmark)

    Yan, Jun; Jacobsen, Karsten Wedel; Thygesen, Kristian Sommer

    2011-01-01

    Linear-response time-dependent density functional theory is used to investigate the relation between molecular bonding and surface plasmons for the model system H/Ag(111). We employ an orbital-dependent exchange-correlation functional to obtain a correct description of the Ag 3d band, which...... is crucial to avoid overscreening the plasmon by the s-d interband transitions. For the clean surface, this approach reproduces the experimental plasmon energies and dispersion to within 0.15 eV. Adsorption of hydrogen shifts and damps the Ag(111) surface plasmon and induces a new peak in the loss function...... at 0.6 eV below the Ag(111) plasmon peak. This feature originates from interband transitions between states located on the hydrogen atoms and states on the Ag surface atoms....

  11. Acute hepatitis B virus infection with simultaneous high HBsAg and high anti-HBs signals in a previously HBV vaccinated HIV-1 positive patient.

    Science.gov (United States)

    van Dommelen, Laura; Verbon, Annelies; van Doorn, H Rogier; Goossens, Valère J

    2010-03-01

    We present a case of a clinical manifest hepatitis B virus infection and a potentially misleading HBV serological profile in an HIV-1 positive patient despite previous HBV vaccination. The patient presented with an acute hepatitis B and there was no indication of chronic HBV infection or the presence of a mutation in the 'a' determinant. Remarkably, simultaneously with high HBV surface antigen and HBV viral load, high anti-HBs antibodies were present. If, due to previous HBV vaccination only anti-HBs was tested in this patient, the result of the high anti-HBs antibodies could be very misleading and offering a false sense of security. Our findings contribute to the ongoing discussion on how to assess HBV specific immunological memory and determining the role of HBV booster vaccinations in immunocompromised individuals.

  12. Long-term effect of interferon plus ribavirin on hepatitis B surface antigen seroclearance in patients dually infected with hepatitis B and C viruses.

    Directory of Open Access Journals (Sweden)

    Ming-Lun Yeh

    Full Text Available BACKGROUND: Interferon-α/ribavirin combination therapy might promote hepatitis B surface antigen (HBsAg seroclearance in patients dually infected with hepatitis B and C viruses (HBV/HCV, but the long-term effect remains unclear. We aimed to investigate the rate of and the factors associated with HBsAg seroclearance during long-term follow-up after interferon-α/ribavirin combination therapy in HBV/HCV dually-infected patients. METHODOLOGY/PRINCIPAL FINDINGS: Eighty-one patients who received interferon-α/ribavirin combination therapy for 24 weeks with a follow-up period of >24 weeks were enrolled. HBV serological markers and HBV DNA were determined every 6 months. Early and late HBsAg seroclearance were defined as HBsAg loss in less or more than 6 months after end-of-treatment, respectively. Fifteen (18.5% patients had HBsAg seroclearance during a mean follow-up period of 3.4 (0.5-5.1 years. The 5-year cumulative incidence was 25.6%. Baseline cirrhosis and HBV DNA negativity 1 year after end-of-treatment were independently predictive of HBsAg seroclearance with an odds ratio (OR, 95% confidence intervals (CI of 16.6, 1.8-153 and 9.2, 1.4-62.1, respectively, by Cox regression hazard analysis. Four patients developed early and 11 developed late HBsAg seroclearance, respectively. Cox regression hazard analysis showed no factor was associated with early HBsAg seroclearance, whilst HBV DNA negativity 1 year after end-of-treatment was the only significant factor predicting late HBsAg loss (OR, 43.0; CI, 2.5-745. Five patients had HBsAg seroconversion with a 5-year cumulative incidence of 8.3%. HBV DNA negativity at baseline and one year after EOT had a trend for HBsAg seroconversion. HCV response did not correlate to HBsAg loss. CONCLUSIONS: We demonstrated that interferon-α/ribavirin had long-term effect on HBsAg seroclearance in dually HBV/HCV-infected patients. Baseline cirrhosis and seroclearance of HBV DNA 1 year after end-of-treatment were

  13. Occult Hbv Infection in Hbsag Negative and Anti-Hbc Positive Blood Donors.

    Directory of Open Access Journals (Sweden)

    A Shebanizadeh

    2007-04-01

    Full Text Available Introduction: In recent years with introduction of better screening tests, the risk of infection with transfusion-transmitted viruses has been reduced remarkably, although obtaining a zero-risk blood supply still remains international blood transfusion services goal. The routine test for detection of HBV infected blood samples is examination of HBsAg with ELISA method but in occult HBV infection, HBsAg is not detectable by ELISA. Therefore, a more sensitive or complementary test is needed. Some international blood transfusion services have introduced anti-HBc screening as a surrogate test for the presence of HBV infection. The aim of this study was to evaluate the prevalence of occult HBV infection in Isfahanian blood donors and the potential value of anti-HBc testing of donors as a screening test to detect occult HBV infection. Methods: In this descriptive cross-sectional study, 545 blood units were collected (from Isfahan blood center and tested by HBsAg ELISA kit from April to June 2004 and then all HBsAg negative samples were tested by anti-HBc ELISA kit. To detect occult HBV infection, all HBsAg negative and anti-HBc positive samples were tested by PCR method. Results: All samples were negative for HBsAg while 43 blood units were anti-HBc positive (8%. These HBsAg negative and anti-HBc positive blood units were tested for HBV DNA of which five units (%11.6 were HBV DNA positive. Conclusion: Occult HBV infection is a clinical form of HBV infection that cannot be detected by usual method (ELISA for HBsAg and therefore more sensitive techniques are needed for detection of HBV infection. PCR is a sensitive technique that detects HBV DNA even in a trace mounts. Our results identified that more sensitive and complementary tests such as, PCR and anti-HBc, are essential and helpful to ensure safety of blood units.

  14. Response-guided therapy of regimens based on PEG-interferon for chronic hepatitis B using on-treatment hepatitis B surface antigen quantification: a meta-analysis.

    Science.gov (United States)

    Peng, Hong; Wei, Fang; Liu, Jun-Ying; Hu, Huai-Dong; Ren, Hong; Hu, Peng

    2015-10-01

    The efficacy of on-treatment hepatitis B surface antigen (HBsAg) levels in guiding pegylated interferon (PEG-IFN) therapy for chronic hepatitis B (CHB) infections is still controversial. The aim of this study is to quantitatively evaluate the efficacy of on-treatment HBsAg levels as a response-guided therapy strategy to guide PEG-IFN-based therapies for CHB. We searched PUBMED, EMBASE, and the Cochrane Library (1997-2013) for clinical research involving HBsAg quantification, and the response to PEG-IFN-based therapy. Pooled effect of HBsAg levels on guiding PEG-IFN-based therapies for CHB was evaluated using fixed-effects or random-effects model. From 13 studies (n = 1493 patients), patients with optimal on-treatment HBsAg levels were found to have a greater chance of attaining a response (RR 5.17, 95 % CI 3.75-7.11, p response rate was 54 % (95 % CI 44-63 %). At week 12, patients without optimal on-treatment HBsAg levels had hardly achieved a response (the early non-response rate: 99 %, 95 % CI 98-100 %). At 24 weeks, the response rate increased to 79 % in HBeAg-negative patients. This meta-analysis suggested that on-treatment HBsAg quantification is effective in guiding the therapy of PEG-IFN in CHB infections, especially in HBeAg-negative patients.

  15. Diagnostic incidence of the presence of positive HBsAg: epidemiologic, clinical, and virological characteristics Incidencia diagnóstica de AgHBs positivo: Características epidemiológicas, clínicas y virológicas

    Directory of Open Access Journals (Sweden)

    Elvira Poves Martínez

    2012-01-01

    Full Text Available Objective: to analyze the epidemiological, clinical, and virological characteristics of patients newly diagnosed with active hepatitis B virus (HBV infection based on the presence of positive hepatitis B surface antigen (HBsAg in the digestive diseases department of a district hospital. Patients and methods: we performed a 3-year prospective study in patients newly diagnosed with HBV infection. We analyzed epidemiological, clinical, and virological characteristics, complete HBV markers, quantification of HBV DNA, and infection by hepatitis delta virus. We performed genotyping and resistance testing in patients with a high viral load. Results were obtained for patients who required liver biopsy. Results: we diagnosed 213 patients (18.8/10,000 inhabitants/year. Men accounted for 61%, and 59% were aged 20 to 40 years. Immigrants accounted for 53% of the population: 46% were from Rumania and 37% from Sub-Saharan African countries. At diagnosis, 2.3% had acute hepatitis (all with jaundice and 3.3% had cirrhosis with portal hypertension. With the exception of cases of acute hepatitis, positive HBeAg was observed in 9%. Serum transaminase levels were normal in 62.2% of patients, HBV DNA was > 2,000 IU/mL in 33.8%, and delta virus was present in 3.3%. Genotyping and resistance testing were performed in 70 patients: the most common genotype was D, followed by A. Resistance was detected at baseline in only 2 cases: to adefovir in one case and to entecavir in another. Among the 36 biopsies performed, 32.4% showed inflammatory activity ≥ 2, and 23.5% had fibrosis ≥ 2 according to the METAVIR scoring system. According to clinical practice, specific treatment for HBV infection was necessary (any reason in 17.4% of those diagnosed (3 patients per 100,000 inhabitants/year. Conclusions: despite prevention and vaccination, HBV infection is a health problem that most commonly affects the immigrant population and men. Serum transaminase levels are normal in 62

  16. Enhanced cell disruption strategy in the release of recombinant hepatitis B surface antigen from Pichia pastoris using response surface methodology

    Directory of Open Access Journals (Sweden)

    Tam Yew

    2012-10-01

    Full Text Available Abstract Background Cell disruption strategies by high pressure homogenizer for the release of recombinant Hepatitis B surface antigen (HBsAg from Pichia pastoris expression cells were optimized using response surface methodology (RSM based on the central composite design (CCD. The factors studied include number of passes, biomass concentration and pulse pressure. Polynomial models were used to correlate the above mentioned factors to project the cell disruption capability and specific protein release of HBsAg from P. pastoris cells. Results The proposed cell disruption strategy consisted of a number of passes set at 20 times, biomass concentration of 7.70 g/L of dry cell weight (DCW and pulse pressure at 1,029 bar. The optimized cell disruption strategy was shown to increase cell disruption efficiency by 2-fold and 4-fold for specific protein release of HBsAg when compared to glass bead method yielding 75.68% cell disruption rate (CDR and HBsAg concentration of 29.20 mg/L respectively. Conclusions The model equation generated from RSM on cell disruption of P. pastoris was found adequate to determine the significant factors and its interactions among the process variables and the optimum conditions in releasing HBsAg when validated against a glass bead cell disruption method. The findings from the study can open up a promising strategy for better recovery of HBsAg recombinant protein during downstream processing.

  17. Enhanced cell disruption strategy in the release of recombinant hepatitis B surface antigen from Pichia pastoris using response surface methodology

    Science.gov (United States)

    2012-01-01

    Background Cell disruption strategies by high pressure homogenizer for the release of recombinant Hepatitis B surface antigen (HBsAg) from Pichia pastoris expression cells were optimized using response surface methodology (RSM) based on the central composite design (CCD). The factors studied include number of passes, biomass concentration and pulse pressure. Polynomial models were used to correlate the above mentioned factors to project the cell disruption capability and specific protein release of HBsAg from P. pastoris cells. Results The proposed cell disruption strategy consisted of a number of passes set at 20 times, biomass concentration of 7.70 g/L of dry cell weight (DCW) and pulse pressure at 1,029 bar. The optimized cell disruption strategy was shown to increase cell disruption efficiency by 2-fold and 4-fold for specific protein release of HBsAg when compared to glass bead method yielding 75.68% cell disruption rate (CDR) and HBsAg concentration of 29.20 mg/L respectively. Conclusions The model equation generated from RSM on cell disruption of P. pastoris was found adequate to determine the significant factors and its interactions among the process variables and the optimum conditions in releasing HBsAg when validated against a glass bead cell disruption method. The findings from the study can open up a promising strategy for better recovery of HBsAg recombinant protein during downstream processing. PMID:23039947

  18. Coating of hydroxyapatite doped Ag on commercially pure titanium surface

    International Nuclear Information System (INIS)

    Vieira, Jonas de Oliveira; Vercik, Luci Cristina de Oliveira; Rigo, Eliana Cristina da Silva

    2012-01-01

    This paper presents results of bioactive coating on commercially pure titanium surface (CpTi) doped with Ag ions. The coating consists of 3 steps, in step 1- surface chemical treatment of the samples with NaOH, step 2 - immersing the substrate in question in a sodium silicate solution (SS) to the nucleation and step 3 - reimmersion these substrates in synthetic solution that simulates the blood serum for precipitation and growth of apatite layer. After the coating step the AgNO 3 substrates were immersed in solutions with concentrations of 20 ppm and 100 ppm at 37 ° C for 48h. The substrates were characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR) and X-ray diffraction (XRD). By the results verified the formation of an apatite layer with aspects of cells, on the surface of CpTi. The increase in Ag concentration causes an increase in Ag amount doped in apatite layer. With the results we concluded that it is possible to obtain an apatite layer on a metal surface as the CpTi doped with Ag ions

  19. Hepatitis B virus surface antigen and anti-hepatitis C virus rapid tests underestimate hepatitis prevalence among HIV-infected patients

    DEFF Research Database (Denmark)

    Hønge, Bo Langhoff; Jespersen, S; Medina, C

    2014-01-01

    OBJECTIVES: In the case of coinfection with HIV and hepatitis B virus (HBV) and/or hepatitis C virus (HCV), hepatic disease progression is often accelerated, with higher rates of liver cirrhosis and liver-related mortality. We aimed to evaluate the performance of the rapid tests used routinely...... to detect HBV surface antigen (HBsAg) and anti-HCV among HIV-infected patients in Guinea-Bissau. METHODS: Blood samples from HIV-infected patients in Guinea-Bissau were stored after testing for HBsAg and anti-HCV with rapid tests. Samples were subsequently re-tested for HBsAg and anti-HCV in Denmark...

  20. Hepatitis B surface antigen quantity positively correlates with plasma levels of microRNAs differentially expressed in immunological phases of chronic hepatitis B in children

    DEFF Research Database (Denmark)

    Winther, Thilde Nordmann; Heiberg, Ida Louise; Bang-Berthelsen, Claus Heiner

    2013-01-01

    Children with chronic hepatitis B (CHB) are at high risk of progressive liver disease. It is suggested that a newly-identified panel of 16 microRNAs is important in the pathogenesis of CHB in children. Subviral hepatitis B surface antigen (HBsAg) particles are produced in large excess over...... infectious virions. Interestingly, circulating HBsAg particles have been shown to carry microRNAs. A thorough characterisation of the identified microRNAs and HBsAg over time in plasma from children with CHB may provide useful information about the natural course of childhood CHB....

  1. Electron spectroscopy studies of surface In-Ag alloy formation on the tungsten surface

    International Nuclear Information System (INIS)

    Bukaluk, A.; Trzcinski, M.; Okulewicz, K.

    2008-01-01

    XPS and UPS investigations of ultrathin films of In/Ag and Ag/In, deposited onto the W(1 1 0) surface in the ultrahigh vacuum conditions have been performed. Indium and silver films were formed by 'in-situ' evaporation on W(1 1 0) substrate. XPS and UPS studies have been performed by means of SCIENTA ESCA200 instrument. The changes of In4d core-level and Ag4d valence band emissions with increasing Ag and In coverage were monitored to observe the energy shift and shape of the spin-orbit doublet of In4d and Ag4d lines in the Ag/In/W and In/Ag/W systems. UPS (HeI and HeII) measurements were supported by XPS AlK α measurements of In3d and W4p levels, as well as by investigations of Ag3d levels. XPS and UPS data allowed to evaluate the coverage and make conclusions concerning intermixing and surface alloying in the In/Ag/W and Ag/In/W systems. W(1 1 0) substrate can be cleaned after each deposition by thermal desorption and no alloying in the In/W and Ag/W systems is observed

  2. Preparation of Ag superhydrophobic surface on metal substrates

    Science.gov (United States)

    Li, J. Y.; Lu, S. X.; Xu, W. G.; Duan, Y. Q.; Yang, X. C.; Cheng, Y. Y.; He, G.; Cui, S.

    2018-01-01

    In this work, the facile approaches are developed for preparation the Ag superhydrophobic surfaces (SHSs) on zinc (Zn), copper (Cu) and aluminium (Al) substrates. The water contact angles (WCAs) of the Ag SHSs on Zn, Cu and Al substrates are 167°, 165° and 154°, respectively. Furthermore, the water sliding angle (WSA) of each surface is less than 1°. The morphology and chemical composition of the samples are characterized using scanning electron microscopy (SEM) and X-ray diffraction pattern (XRD). The as-prepared three kinds of SHSs possess the self-cleaning performance, which can quickly take the chalk away when the water droplets fall down the SHSs. In addition, the superhydrophobicity of the SHSs can well maintain after exposure to the air for 6 months, indicating that the surfaces can sustain good stability.

  3. Seroprevalence and risk factors of hepatitis B virus surface antigen among the workers in a garment factory

    Directory of Open Access Journals (Sweden)

    Mohammad Mizanur Rahman

    2017-11-01

    Full Text Available The purpose of this study is to find out the prevalence of seropositivity and risk factors associated with hepatitis B virus infection. A total of 2,737 readymade garment workers were initially screened after getting departmental as well as the individuals consent and simultaneously a questionnaire was filled up by the field research assistants to assess the risk factors. Initially 59 cases were found positive for hepatitis B virus surface antigen (HBsAg by immunochromato-graphic test. Enzyme linked immunosorbant technique was then applied to the screened positive HBsAg individuals and four cases turned out as negative and therefore a total of 55  HBsAg positive cases were detected in this factory. Statistically significant risk factors associated with HBsAg positivity were jaundice, history of previous surgery and accident, needle stick injuries and unsafe injections. This study concludes that the seropositivity found garment workers is similar to the general population of Bangladesh.

  4. Surface alloy formation by adsorption of holmium on Ag/Mo(112) bimetallic surfaces

    Science.gov (United States)

    Kołaczkiewicz, Jan; Oleksy, Czesław

    2018-03-01

    Work function change measurements, low energy electron diffraction (LEED) and density functional theory (DFT) are used to determine the structures formed on Ag/Mo(112) bimetallic surfaces upon deposition of 0.5 monolayer (ML) of holmium. As the bimetallic surfaces, we have chosen the Mo(112) substrate covered with 1 or 2 ML of Ag. Such surfaces have the same symmetry as the Mo(112) face but different electronic properties. LEED experiment indicates that the c(2 × 2) structure is formed on (1 ML Ag)/Mo(112) bimetallic surface upon deposition of 0.5 ML of Ho. DFT calculations show that a type of Ag-Ho surface alloy is formed, with Ho atoms 0.6 Å below the distorted layer of Ag. This is neither a substitutional nor a subsurface alloy. It is found that the adsorption structure formed on the (2 ML Ag)/Mo(112) bimetallic surface depends on the annealing temperature. After deposition of 0.5 ML of Ho at 300 K, the LEED pattern of p(2 × 2) symmetry is observed. Annealing of the overlayer at 640 K irreversibly changes the p(2 × 2) pattern into a pattern of c(2 × 2) type. The results of DFT computations show that the c(2 × 2) structure of the Ag-Ho surface alloy is energetically most favorable. In this structure, 0.5 ML of Ho is between the two monolayers of Ag, and the symmetry of the topmost layer is changed. The work function change calculated for the c(2 × 2) structure is in a good agreement with the measured value (0.22 eV). The results show that adsorption of Ho on the Ag/Mo(112) bimetallic surfaces is substantially different than on the clean Mo(112).

  5. Safety of using hepatitis B virus core antibody or surface antigen-positive donors in kidney or pancreas transplantation.

    Science.gov (United States)

    Akalin, Enver; Ames, Scott; Sehgal, Vinita; Murphy, Barbara; Bromberg, Jonathan S

    2005-06-01

    Hepatitis B virus core antibody (HBcAb) or surface antigen (HBsAg)-positive organ donors have the potential to transmit infection to transplant recipients. We investigated the safety of using HBcAb(+) or HBsAg(+) donors in kidney or pancreas transplant recipients with 1 yr lamivudine prophylaxis. While HBsAb(-) recipients of HBcAb(+) donors received prophylaxis, HBsAb(+) recipients did not. HBsAg(+) organs were only used in patients who were both HBcAb and HBsAb(+). Forty-six patients received HBcAb(+) and four received HBsAg(+) organs (47 kidney, two pancreas, and one kidney/pancreas). All but one recipient were HBsAg(-), 25 were HBsAb(+), and 19 HBcAb(+). During a median 36 months of follow-up (range 6-66 months), with 43 of a total 50 patients having at least 1 yr follow-up and were off lamivudine, and none of the patients developed hepatitis B viremia or seroconversion to HBsAg or HBsAb(+). These results suggest that HBcAb(+) or HBsAg(+) organs can be used safely in selected recipients with lamivudine prophylaxis without requiring hepatitis B immunglobulin.

  6. A simple and inexpensive point-of-care test for hepatitis B surface antigen detection: serological and molecular evaluation.

    Science.gov (United States)

    Gish, R G; Gutierrez, J A; Navarro-Cazarez, N; Giang, K; Adler, D; Tran, B; Locarnini, S; Hammond, R; Bowden, S

    2014-12-01

    Early identification of chronic hepatitis B is important for optimal disease management and prevention of transmission. Cost and lack of access to commercial hepatitis B surface antigen (HBsAg) immunoassays can compromise the effectiveness of HBV screening in resource-limited settings and among marginalized populations. High-quality point-of-care (POC) testing may improve HBV diagnosis in these situations. Currently available POC HBsAg assays are often limited in sensitivity. We evaluated the NanoSign(®) HBs POC chromatographic immunoassay for its ability to detect HBsAg of different genotypes and with substitutions in the 'a' determinant. Thirty-seven serum samples from patients with HBV infection, covering HBV genotypes A-G, were assessed for HBsAg titre with the Roche Elecsys HBsAg II quantification assay and with the POC assay. The POC assay reliably detected HBsAg at a concentration of at least 50 IU/mL for all genotypes, and at lower concentrations for some genotypes. Eight samples with substitutions in the HBV 'a' determinant were reliably detected after a 1/100 dilution. The POC strips were used to screen serum samples from 297 individuals at risk for HBV in local clinical settings (health fairs and outreach events) in parallel with commercial laboratory HBsAg testing (Quest Diagnostics EIA). POC testing was 73.7% sensitive and 97.8% specific for detection of HBsAg. Although the POC test demonstrated high sensitivity over a range of genotypes, false negatives were frequent in a clinical setting. Nevertheless, the POC assay offers advantages for testing in both developed and resource-limited countries due to its low cost (0.50$) and immediately available results. © 2014 John Wiley & Sons Ltd.

  7. Synthesis of Ag-coated polystyrene colloids by an improved surface seeding and shell growth technique

    International Nuclear Information System (INIS)

    Tian Chungui; Wang Enbo; Kang Zhenhui; Mao Baodong; Zhang Chao; Lan Yang; Wang Chunlei; Song Yanli

    2006-01-01

    In this paper, an improved surface seeding and shell growth technique was developed to prepare Ag-polystyrene core shell composite. Polyethyleneimine (PEI) could act as the linker between Ag ions (Ag nanoparticles) and polystyrene (PS) colloids and the reducing agent in the formation of Ag nanoparticles. Due to the multi-functional characteristic of PEI, Ag seeds formed in-situ and were immobilized on the surface of PEI-modified PS colloids and no free Ag clusters coexist with the Ag 'seeding' PS colloids in the system. Then, the additional agents could be added into the resulting dispersions straightly to produce a thick Ag nanoshell. The Ag nanoshell with controllable thickness was formed on the surface of PS by the 'one-pot' surface seeding and shell growth method. The Ag-coverage increased gradually with the increasing of mass ratio of AgNO 3 /PS. The optical properties of the Ag-PS colloids could be tailored by changing the coverage of Ag. - Graphical abstract: An improved surface seeding and shell growth technique was developed to prepare Ag-polystyrene core shell composite. The optical properties of the Ag-PS colloids could be tailored by changing the coverage of Ag. Display Omitted

  8. Surface plasmon resonance of Ag organosols: Experimental and theoretical investigations

    Directory of Open Access Journals (Sweden)

    Vodnik Vesna

    2012-01-01

    Full Text Available The aim of this paper is to investigate and compare the changes in surface plasmon resonance (SPR of silver (Ag hydrosol and organosols obtained by experimental and theoretical approaches. Silver nanoparticles (Ag NPs of 5 ± 1.5 nm in diameter were prepared in water by reduction of silver nitrate with sodium borohydride. Nanoparticles were subsequently transferred into different organic solvents (chloroform, hexane, toluene, 1,2-dichlorobenzene using oleylamine as a transfer agent. These solvents were chosen because of the differences in their refractive indices. Using UV-Vis absorption spectrophotometry and transmission electron microscopy (TEM, we confirmed that there were no shape and size changes of the nanoparticles upon the transfer to the organic phase. The absorption spectra of the obtained Ag organosols showed only changes in the position of SPR band depending on dielectric property of the used solvent. To analyze these changes, absorption spectra were modelled using Mie theory for small spherical particles. The experimental and theoretical resonance values were compared with those predicted by Drude model and its limitations in the analysis of absorption behavior of Ag NPs in organic solvents were briefly discussed.

  9. Surface science study of selective ethylene epoxidation catalyzed by the Ag(110) surface: Structural sensitivity

    International Nuclear Information System (INIS)

    Campbell, C.T.

    1984-01-01

    The selective oxidation of ethylene to ethylene epoxide (C 2 H 4 +1/2O 2 →C 2 H 4 O) over Ag is the simplest example of kinetically controlled, selective heterogeneous catalysis. We have studied the steady-state kinetics and selectivity of this reaction for the first time on a clean, well-characterized Ag(110) surface by using a special apparatus which allows rapid (approx.20 s) transfer between a high-pressure catalytic microreactor and an ultrahigh vacuum surface analysis (AES, XPS, LEED, TDS) chamber. The effects of temperature and reactant pressures upon the rate and selectivity are virtually identical on Ag(110) and supported, high surface area Ag catalysts. The absolute specific rate (per Ag surface atom) is, however, some 100-fold higher for Ag(110) than for high surface area catalysts. This is related to the well-known structural sensitivity of this reaction. It is postulated that a small percentage of (110) planes (or [110]-like sites) are responsible for most of the catalytic activity of high surface area catalysts. The high activity of the (110) plane is attributed to its high sticking probability for dissociative oxygen adsorption, since the rate of ethylene epoxidation is shown in a related work [Ref. 1: C. T. Campbell and M. T. Paffett, Surf. Sci. (in press)] to be proportional to the coverage of atomically adsorbed oxygen at constant temperature and ethylene pressure

  10. Tailoring the surface chemical bond states of the NbN films by doping Ag: Achieving hard hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ping; Zhang, Kan; Du, Suxuan [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Meng, Qingnan [College of Construction Engineering, Jilin University, Changchun, 130026 (China); He, Xin [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Wang, Shuo [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Wen, Mao, E-mail: wenmao225@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China); Zheng, Weitao, E-mail: WTZheng@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, 130012 (China)

    2017-06-15

    Highlights: • Intrinsically hydrophilic NbN films can transfer to hydrophobic Nb-Ag-N films by doping Ag atoms into NbN sublattice. • Solute Ag can promote that the hydrophobic Ag{sub 2}O groups formed on the Nb-Ag-N film surface through self-oxidation. • The present work may provide a straightforward approach for the production of robust hydrophobic ceramic surfaces. - Abstract: Robust hydrophobic surfaces based on ceramics capable of withstanding harsh conditions such as abrasion, erosion and high temperature, are required in a broad range of applications. The metal cations with coordinative saturation or low electronegativity are commonly chosen to achieve the intrinsically hydrophobic ceramic by reducing Lewis acidity, and thus the ceramic systems are limited. In this work, we present a different picture that robust hydrophobic surface with high hardness (≥20 GPa) can be fabricated through doping Ag atoms into intrinsically hydrophilic ceramic film NbN by reactive co-sputtering. The transition of wettability from hydrophilic to hydrophobic of Nb-Ag-N films induced by Ag doping results from the appearance of Ag{sub 2}O groups on the films surfaces through self-oxidation, because Ag cations (Ag{sup +}) in Ag{sub 2}O are the filled-shell (4d{sup 10}5S{sup 0}) electronic structure with coordinative saturation that have no tendency to interact with water. The results show that surface Ag{sub 2}O benefited for hydrophobicity comes from the solute Ag atoms rather than precipitate metal Ag, in which the more Ag atoms incorporated into Nb-sublattice are able to further improve the hydrophobicity, whereas the precipitation of Ag nanoclusters would worsen it. The present work opens a window for fabricating robust hydrophobic surface through tailoring surface chemical bond states by doping Ag into transition metal nitrides.

  11. Surface-engineered growth of AgIn₅S₈ crystals.

    Science.gov (United States)

    Lai, Chia-Hung; Chiang, Ching-Yeh; Lin, Po-Chang; Yang, Kai-Yu; Hua, Chi Chung; Lee, Tai-Chou

    2013-05-01

    The growth of semiconductor crystals and thin films plays an essential role in industry and academic research. Considering the environmental damage caused by energy consumption during their fabrication, a simpler and cheaper method is desired. In fact, preparing semiconductor materials at lower temperatures using solution chemistry has potential in this research field. We found that solution chemistry, the physical and chemical properties of the substrate surface, and the phase diagram of the multicomponent compound semiconductor have a decisive influence on the crystal structure of the material. In this study, we used self-assembled monolayers (SAMs) to modify the silicon/glass substrate surface and effectively control the density of the functional groups and surface energy of the substrates. We first employed various solutions to grow octadecyltrichlorosilane (OTS), 3-mercaptopropyl-trimethoxysilane (MPS), and mixed OTS-MPS SAMs. The surface energy can be adjusted between 24.9 and 50.8 erg/cm(2). Using metal sulfide precursors in appropriate concentrations, AgIn5S8 crystals can be grown on the modified substrates without any post-thermal treatment. We can easily adjust the nucleation in order to vary the density of AgIn5S8 crystals. Our current process can achieve AgIn5S8 crystals of a maximum of 1 μm in diameter and a minimum crystal density of approximately 0.038/μm(2). One proof-of-concept experiment demonstrated that the material prepared from this low temperature process showed positive photocatalytic activity. This method for growing crystals can be applied to the green fabrication of optoelectronic materials.

  12. Pectinesterase Inhibitor from Jelly Fig (Ficus awkeotsang Makino Achene Inhibits Surface Antigen Expression by Human Hepatitis B Virus

    Directory of Open Access Journals (Sweden)

    Yu-Chuen Huang

    2013-01-01

    Full Text Available Pectinesterase inhibitor (PEI isolated from jelly fig (Ficus awkeotsang Makino is an edible component of a popular drink consumed in Asia. Hepatitis B virus (HBV infection is prevalent in Asia, and current treatments for HBV infection need improvement. This study aimed to evaluate the effect of PEI on the surface antigen expression by HBV (HBsAg. Human hepatoma cell lines Hep3B and Huh7 served as in vitro models for assessing the cytotoxicity and HBsAg expression. A culture of primary hepatocytes cultured from mice served as the normal counterpart. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT colorimetric assay. HBsAg expression was evaluated by measuring HBsAg secretion into the culture medium using an enzyme-linked immunosorbent assay. The results showed that PEI did not affect the viability of the human hepatoma cell lines or primary mouse hepatocytes. PEI inhibited the expression of HBsAg in hepatoma cell lines harboring endogenous (Hep3B and integrated (Huh7 HBV genomes in a concentration- and time-dependent manner, thus implicating a universal activity against HBV gene expression. In conclusion, it suggests that PEI from jelly fig inhibits the expression of human HBsAg in host cells without toxic effects on normal primary hepatocytes.

  13. Pectinesterase Inhibitor from Jelly Fig (Ficus awkeotsang Makino) Achene Inhibits Surface Antigen Expression by Human Hepatitis B Virus.

    Science.gov (United States)

    Huang, Yu-Chuen; Jiang, Chii-Ming; Chen, Yu-Jen; Chen, Yu-Yawn

    2013-01-01

    Pectinesterase inhibitor (PEI) isolated from jelly fig (Ficus awkeotsang Makino) is an edible component of a popular drink consumed in Asia. Hepatitis B virus (HBV) infection is prevalent in Asia, and current treatments for HBV infection need improvement. This study aimed to evaluate the effect of PEI on the surface antigen expression by HBV (HBsAg). Human hepatoma cell lines Hep3B and Huh7 served as in vitro models for assessing the cytotoxicity and HBsAg expression. A culture of primary hepatocytes cultured from mice served as the normal counterpart. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. HBsAg expression was evaluated by measuring HBsAg secretion into the culture medium using an enzyme-linked immunosorbent assay. The results showed that PEI did not affect the viability of the human hepatoma cell lines or primary mouse hepatocytes. PEI inhibited the expression of HBsAg in hepatoma cell lines harboring endogenous (Hep3B) and integrated (Huh7) HBV genomes in a concentration- and time-dependent manner, thus implicating a universal activity against HBV gene expression. In conclusion, it suggests that PEI from jelly fig inhibits the expression of human HBsAg in host cells without toxic effects on normal primary hepatocytes.

  14. Thermal Diffusion Dynamic Behavior of Two-Dimensional Ag-SMALL Clusters on Ag(1 1 1) Surface

    Science.gov (United States)

    Zakirur-Rehman; Hayat, Sardar Sikandar

    2015-07-01

    In this paper, the thermal diffusion behavior of small two-dimensional Ag-islands on Ag(1 1 1) surface has been explored using molecular dynamics (MD) simulations. The approach is based on semi-empirical potentials. The key microscopic processes responsible for the diffusion of Ag1-5 adislands on Ag(1 1 1) surface are identified. The hopping and zigzag concerted motion along with rotation are observed for Ag one-atom to three-atom islands while single-atom and multi-atom processes are revealed for Ag four-atom and five-atom islands, during the diffusion on Ag(1 1 1) surface. The same increasing/decreasing trend in the diffusion coefficient and effective energy barrier is observed in both the self learning kinetic Monte Carlo (SLKMC) and MD calculations, for the temperature range of 300-700 K. An increase in the value of effective energy barrier is noticed with corresponding increase in the number of atoms in Ag-adislands. A reasonable linear fit is observed for the diffusion coefficient for studied temperatures (300, 500 and 700 K). For the observed diffusion mechanisms, our findings are in good agreement with ab initio density-functional theory (DFT) calculations for Al/Al(1 1 1) while the energy barrier values are in same range as the experimental values for Cu/Ag(1 1 1) and the theoretical values using ab initio DFT supplemented with embedded-atom method for Ag/Ag(1 1 1).

  15. Transformation of tobacco plant (Nicotiana tabacum L. with the recombinant hepatitis B virus genes 35SHBsAg and 35SHBsAgER

    Directory of Open Access Journals (Sweden)

    Juliana Martins Ribeiro

    2010-03-01

    Full Text Available The recombinant surface antigen of hepatitis B virus (HBsAg, purified from transgenic plants, proved to be efficient when utilized for raising anti-HB antibodies for the prevention of hepatitis B. Because of the important role of the HBsAg antigen in hepatitis B prevention, the coding sequence of HBsAg antigen, with or without the addition of the carboxi-terminus sequence for protein retention in the endoplasmatic reticulum, was linked to cauliflower mosaic virus 35S promoter, tobacco mosaic virus leader sequence Ω, and the transcription terminator sequence. The aim of this work was to clone the chimeric gene 35SHBsAgER in the plant expression vector pGPTV/Kan/Asc. The resulting plasmid, called pG35SHBsAgER, and another plasmid produced previously in our laboratory called pG35SHBsAg, were transferred to Agrobacterium tumefaciens, and tobacco leaves, of the SR1 cultivar were used as explants for genetic transformation. Twenty-one fully regenerated plants were obtained (10 for the pG35SHBsAg construction and 11 for the pG35SHBsAgER construction. The genomic DNA of all plants was analyzed by PCR, and the presence of the transgene was confirmed in all plants.

  16. Surface- and tip-enhanced Raman scattering of bradykinin onto the colloidal suspended Ag surface.

    Science.gov (United States)

    Swiech, D; Ozaki, Y; Kim, Y; Proniewicz, E

    2015-07-14

    In this paper, surface- (SERS) and tip-enhanced Raman scattering (TERS) techniques were used to determine the adsorption mode of bradykinin (BK), a small peptide implicated in, for example, carcinoma growth, onto colloidal suspended Ag surfaces under various environmental conditions, including: peptide concentrations (10(-5)-10(-7) M), excitation wavelengths (514.5 and 785.0 nm), and pH of aqueous sol solutions (from pH = 3 to pH = 11). The metal surface plasmon and rheology of the colloidal suspended Ag surface were explored by ultraviolet-visible (UV-Vis) spectroscopy and atomic force/scanning electron microscopy (AFM/SEM). The SERS results indicated that the peptide concentration of 10(-5) M was the optimal peptide concentration for monolayer colloidal coverage. The Phe(5/8) and Arg(9) residues of BK generally participated in the interactions with colloidal suspended Ag surfaces. The amide group appeared to be arranged in the same manner to the Ag surface in the pH range of 3 to 11. At acidic pH of the solution (pH = 3 to 5), the BK -COO(-) terminal group binds to the Ag surface as a bidentate (at pH = 3) or monodentate (at pH = 5) chelating ligand. At pH = 11, the imino group of Arg(9), probably due to its -C[double bond, length as m-dash]N(⊕)H2 protonation state, was not involved in the interaction with Ag. The reduction in the solution alkalinity (pH = 9) produced the deprotonation of the -C=N(⊕)H2 group followed by group rearrangement in a way favoring the interaction between the lone electron pair on N and Ag. The TERS studies confirmed the proposed, on the basis of SERS, behavior of BK onto the colloidal suspended Ag at pH = 7 and showed that in different points of the colloidal suspended Ag surface the same peptide fragments approximately having the same orientations with respect to this surface interact with it.

  17. Stability of underpotentially deposited Ag layers on a Au(111) surface studied by surface X-ray scattering

    OpenAIRE

    Kondo, Toshihiro; Takakusagi, Satoru; Uosaki, Kohei

    2009-01-01

    Stability of underpotentially deposited (upd) Ag layers on Au(111) surface was investigated by surface X-ray scattering (SXS). While the complete pseudomorphic Ag bilayer on Au(111) surface obtained by upd at 10 mV (vs. Ag/Ag+) was maintained its structure even after the circuit was disconnected and the surface was exposed to ambient atmosphere, the pseudomorphic Ag monolayer obtained by upd at 50 mV was converted to a partial bilayer with the coverage of 0.66 ML and 0.46 ML for the 1st and 2...

  18. In Situ Liver Expression of HBsAg/CD3-Bispecific Antibodies for HBV Immunotherapy

    Directory of Open Access Journals (Sweden)

    Robert L. Kruse

    2017-12-01

    Full Text Available Current therapies against hepatitis B virus (HBV do not reliably cure chronic infection, necessitating new therapeutic approaches. The T cell response can clear HBV during acute infection, and the adoptive transfer of antiviral T cells during bone marrow transplantation can cure patients of chronic HBV infection. To redirect T cells to HBV-infected hepatocytes, we delivered plasmids encoding bispecific antibodies directed against the viral surface antigen (HBsAg and CD3, expressed on almost all T cells, directly into the liver using hydrodynamic tail vein injection. We found a significant reduction in HBV-driven reporter gene expression (184-fold in a mouse model of acute infection, which was 30-fold lower than an antibody only recognizing HBsAg. While bispecific antibodies triggered, in part, antigen-independent T cell activation, antibody production within hepatocytes was non-cytotoxic. We next tested the bispecific antibodies in a different HBV mouse model, which closely mimics the transcriptional template for HBV, covalently closed circular DNA (cccDNA. We found that the antiviral effect was noncytopathic, mediating a 495-fold reduction in HBsAg levels at day 4. At day 33, bispecific antibody-treated mice exhibited 35-fold higher host HBsAg immunoglobulin G (IgG antibody production versus untreated groups. Thus, gene therapy with HBsAg/CD3-bispecific antibodies represents a promising therapeutic strategy for patients with HBV.

  19. Surface topographical and structural analysis of Ag+-implanted polymethylmethacrylate

    International Nuclear Information System (INIS)

    Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Naab, Fabian; Toader, Ovidiu; Sagheer, Riffat; Bashir, Shazia; Zia, Rehana; Siraj, Khurram; Iqbal, Saman

    2016-01-01

    Specimens of polymethylmethacrylate (PMMA) were implanted with 400-keV Ag + ions at different ion fluences ranging from 1 × 10 14 to 5 × 10 15 ions/cm 2 using a 400-kV NEC ion implanter. The surface topographical features of the implanted PMMA were investigated by a confocal microscope. Modifications in the structural properties of the implanted specimens were analyzed in comparison with pristine PMMA by X-ray diffraction (XRD) and Raman spectroscopy. UV–Visible spectroscopy was applied to determine the effects of ion implantation on optical transmittance of the implanted PMMA. The confocal microscopic images revealed the formation of hillock-like microstructures along the ion track on the implanted PMMA surface. The increase in ion fluence led to more nucleation of hillocks. The XRD pattern confirmed the amorphous nature of pristine and implanted PMMA, while the Raman studies justified the transformation of Ag + -implanted PMMA into amorphous carbon at the ion fluence of ⩾5 × 10 14 ions/cm 2 . Moreover, the decrease in optical transmittance of PMMA is associated with the formation of hillocks and ion-induced structural modifications after implantation.

  20. Surface antigen-negative hepatitis B virus infection in Dutch blood donors

    NARCIS (Netherlands)

    Lieshout-Krikke, R. W.; Molenaar-de Backer, M. W. A.; van Swieten, P.; Zaaijer, H. L.

    2014-01-01

    Hepatitis B virus (HBV) surface antigen (HBsAg) is a reliable marker for HBV infection, but HBsAg-negative forms of HBV infection occur. The introduction of HBV DNA screening of Dutch blood donors, which were not preselected for absence of HBV core antibodies, enabled the characterization of

  1. Investigation of the electron emission properties of silver: From exposed to ambient atmosphere Ag surface to ion-cleaned Ag surface

    Energy Technology Data Exchange (ETDEWEB)

    Gineste, T., E-mail: Thomas.Gineste@onera.fr [ONERA The French Aerospace Lab, 31055 Toulouse (France); Belhaj, M. [ONERA The French Aerospace Lab, 31055 Toulouse (France); Teyssedre, G. [LAPLACE - Laboratoire Plasma et Conversion d’Energie -UMR 5213, Université Paul Sabatier - 118, route de Narbonne, 31062 Toulouse Cedex (France); Puech, J. [CNES, 18 Avenue Edouard Belin 31055 Toulouse Cédex 9 (France)

    2015-12-30

    Highlights: • We investigated the electron emission yield of an air exposed Ag to a cleaned Ag. • Air exposed Ag sample was cleaned by ion Ar etching. • Surface composition was determined by AES. • Electron emission yield was related to surface composition evolution. • Natural contamination hugely influence electron properties of Ag sample. - Abstract: Electron emission properties of materials are highly dependent to the surface and the first nanometres subsurface. Technical materials, i.e. used within applications are ordinarily exposed to atmosphere, which interacts with the surface. The contamination layer building up at the surface of materials and/or oxidation layer affects dramatically the electron emission proprieties. In this paper, starting from 99.99% pure silver sample, exposed 4 years to ambient atmosphere, we monitored the variations of the electron emission properties and the surface composition during step by step ion etching procedure.

  2. The effect of surface structure on Ag atom adsorption over CuO(111) surfaces: A first principles study

    Science.gov (United States)

    Hu, Riming; Zhou, Xiaolong; Yu, Jie

    2017-12-01

    The interactions of Ag atom with different types of CuO(111) surface, including the perfect, oxygen-vacancy and precovered oxygen surfaces, have been systematically investigated using density functional theory (DFT) calculations to examine the effect of surface structures on Ag atom adsorption. The calculated results indicate that the Cu1-Cu1 bridge site and the oxygen-vacancy site are the active centres for atomic Ag adsorption on the perfect surface and the oxygen-vacancy surface respectively, while atomic Ag preferentially adsorbs at the Op site on the precovered oxygen surface. The activity of the CuO(111) surface for atomic Ag adsorption can be improved both on the perfect and oxygen-vacancy surfaces, while the activity of the CuO(111) surface for atomic Ag adsorption will be suppressed on precovered oxygen surfaces. Furthermore, the adsorption of NO on different CuO(111) surfaces with Ag adsorption was investigated, and the calculation results show that the adsorption of NO on an Ag-loaded CuO(111) surface is greater than that on the pure CuO(111) surface.

  3. Study of Ag induced bimetallic (Au-Ag) nanowires on silicon (5 5 12) surfaces: Experiment and theoretical aspects

    Science.gov (United States)

    Bhukta, Anjan; Bagarti, Trilochan; Guha, Puspendu; Ravulapalli, Sathyavathi; Satpati, Biswarup; Rakshit, Bipul; Maiti, Paramita; Parlapalli, Venkata Satyam

    2017-10-01

    The reconstructed vicinal (high index) silicon surfaces, such as, Si (5 5 12) composes row-like structures that can be used as templates for growing aligned nanowires. By using a sub-monolayers of Ag, prior to Au deposition on reconstructed Si (5 512) surface, intermixing of Au and Ag, enhancement of aspect ratio of bimetallic Au-Ag nanowires with tunable morphology is reported. This is attributed to a combined effect of pre-grown Ag strips as nucleation centers for incoming Au ad-atoms and anisotropic Au-Ag intermixing. To achieve optimum conditions for the growth of larger aspect ratio Au-Ag nanostructures, the growth kinetics have been studied by varying growth and annealing temperatures. At ≈400 °C, the Ag diffused into silicon substrate and the inter-diffusion found to inhibit the formation of Au-Ag bimetallic nanostructures. Controlled experiments under ultra-high vacuum condition in a molecular beam epitaxy system and in-situ scanning tunneling microscopy measurements along with ex-situ scanning transmission and secondary electron microscopy measurements have been carried out to understand the bimetallic nanostructure growth. Kinetic Monte Carlo (KMC) simulations based on kinematics of ad-atoms on an anisotropic template with a solid on solid model in which the relative ratios of binding energies (that are obtained from the Density Functional Theory) have been used and the KMC simulations results agree with the experimental observations. Advantage of having bimetallic structures as effective substrates for Surface enhanced Raman spectroscopy application is demonstrated by detecting Rhodamine 6 G (R6G) molecule at the concentration of 10-7M.

  4. Surface Pourbaix diagrams and oxygen reduction activity of Pt, Ag and Ni(111) surfaces studied by DFT

    DEFF Research Database (Denmark)

    Hansen, Heine Anton; Rossmeisl, Jan; Nørskov, Jens Kehlet

    2008-01-01

    The electrochemical most stable surface structures is investigated as function of pH and potential for Pt, Ag and Ni based on DFT calculations and constructed surface Pourbaix diagrams. It is also explained why metals such as Ag and Ni may be used successfully in alkaline fuel cells but not in ac......The electrochemical most stable surface structures is investigated as function of pH and potential for Pt, Ag and Ni based on DFT calculations and constructed surface Pourbaix diagrams. It is also explained why metals such as Ag and Ni may be used successfully in alkaline fuel cells...

  5. Influence of the surface properties on bactericidal and fungicidal activity of magnetron sputtered Ti–Ag and Nb–Ag thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wojcieszak, D., E-mail: damian.wojcieszak@pwr.edu.pl [Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wrocław (Poland); Mazur, M.; Kaczmarek, D. [Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wrocław (Poland); Mazur, P. [Institute of Experimental Physics, University of Wrocław, Max Born 9, 50-204 Wrocław (Poland); Szponar, B. [Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla 12, 53–114 Wrocław (Poland); Domaradzki, J. [Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wrocław (Poland); Kepinski, L. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland)

    2016-05-01

    In this study the comparative investigations of structural, surface and bactericidal properties of Ti–Ag and Nb–Ag thin films have been carried out. Ti–Ag and Nb–Ag coatings were deposited on silicon and fused silica substrates by magnetron co-sputtering method using innovative multi-target apparatus. The physicochemical properties of prepared thin films were examined with the aid of X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy methods. Moreover, the wettability of the surface was determined. It was found that both, Ti–Ag and Nb–Ag thin films were nanocrystalline. In the case of Ag–Ti film presence of AgTi{sub 3} and Ag phases was identified, while in the structure of Nb–Ag only silver occurred in a crystal form. In both cases the average size of crystallites was ca. 11 nm. Moreover, according to scanning electron microscopy and atomic force microscopy investigations the surface of Nb–Ag thin films was covered with Ag-agglomerates, while Ti–Ag surface was smooth and devoid of silver particles. Studies of biological activity of deposited coatings in contact with Bacillus subtilis, Pseudomonas aeruginosa, Enterococcus hirae, Klebisiella pneumoniae, Escherichia coli, Staphylococcus aureus and Candida albicans were performed. It was found that prepared coatings were bactericidal and fungicidal even in a short term-contact, i.e. after 2 h. - Highlights: • Surface and biological properties of Ti–Ag and Nb–Ag thin films were examined. • Ag content was related to sputtering yields and nucleation of Ti and Nb. • For Nb–Ag film the agglomeration of silver at the surface was observed. • Composition and surface topography had an impact on antimicrobial properties. • Fine-grained surface was important in Ag ions release process.

  6. Hepatitis B virus surface antigen (HBsAg)-positive and HBsAg-negative hepatitis B virus infection among mother-teenager pairs 13 years after neonatal hepatitis B virus vaccination.

    Science.gov (United States)

    Yao, Qing-Qing; Dong, Xiao-Lian; Wang, Xue-Cai; Ge, Sheng-Xiang; Hu, An-Qun; Liu, Hai-Yan; Wang, Yueping Alex; Yuan, Quan; Zheng, Ying-Jie

    2013-02-01

    It is unclear whether a mother who is negative for hepatitis B virus surface antigen (HBsAg) but positive for hepatitis B virus (HBV) is at potential risk for mother-to-child transmission of HBV. This study, using a paired mother-teenager population, aimed to assess whether maternal HBsAg-negative HBV infection ((hn)HBI) is a significant source of child HBV infection (HBI). A follow-up study with blood collection has been conducted on the 93 mother-teenager pairs from the initial 135 pregnant woman-newborn pairs 13 years after neonatal HBV vaccination. Serological and viral markers of HBV have been tested, and phylogenetic analysis of HBV isolates has been done. The HBI prevalence was 1.9% (1 (hn)HBI/53) for teenage children of non-HBI mothers, compared with 16.7% (1 (hn)HBI/6) for those of (hn)HBI mothers and 2.9% (1 HBsAg-positive HBV infection [(hp)HBI]/34) for those of (hp)HBI mothers. Similar viral sequences have been found in one pair of whom both the mother and teenager have had (hn)HBI. In comparison with the (hp)HBI cases, those with (hn)HBI had a lower level of HBV load and a higher proportion of genotype-C strains, which were accompanied by differentiated mutations (Q129R, K141E, and Y161N) of the "a" determinant of the HBV surface gene. Our findings suggest that mother-to-teenager transmission of (hn)HBI can occur among those in the neonatal HBV vaccination program.

  7. Localization of immunodominant epitopes within the "a" determinant of hepatitis B surface antigen using monoclonal antibodies.

    Science.gov (United States)

    Golsaz-Shirazi, Forough; Mohammadi, Hamed; Amiri, Mohammad Mehdi; Khoshnoodi, Jalal; Kardar, Gholam Ali; Jeddi-Tehrani, Mahmood; Shokri, Fazel

    2016-10-01

    The common "a" determinant is the major immunodominant region of hepatitis B surface antigen (HBsAg) shared by all serotypes and genotypes of hepatitis B virus (HBV). Antibodies against this region are thought to confer protection against HBV and are essential for viral clearance. Mutations within the "a" determinant may lead to conformational changes in this region, which can affect the binding of neutralizing antibodies. There is an increasing concern about identification and control of mutant viruses which is possible by comprehensive structural investigation of the epitopes located within this region. Anti-HBs monoclonal antibodies (mAbs) against different epitopes of HBsAg are a promising tool to meet this goal. In the present study, 19 anti-HBs mAbs were employed to map epitopes localized within the "a" determinant, using a panel of recombinant mutant HBsAgs. The topology of the epitopes was analyzed by competitive enzyme-linked immunosorbent assay (ELISA). Our results indicate that all of the mAbs seem to recognize epitopes within or in the vicinity of the "a" determinant of HBsAg. Different patterns of binding with mutant forms were observed with different mAbs. Amino acid substitutions at positions 123, 126, 129, 144, and 145 dramatically reduced the reactivity of antibodies with HBsAg. The T123N mutation had the largest impact on antibody binding to HBsAg. The reactivity pattern of our panel of mAbs with mutant forms of HBsAg could have important clinical implications for immunoscreening, diagnosis of HBV infection, design of a new generation of recombinant HB vaccines, and immunoprophylaxis of HBV infection as an alternative to therapy with hepatitis B immune globulin (HBIG).

  8. Enhanced immunogenicity of DNA fusion vaccine encoding secreted hepatitis B surface antigen and chemokine RANTES

    International Nuclear Information System (INIS)

    Kim, Seung Jo; Suh, Dongchul; Park, Sang Eun; Park, Jeong-Sook; Byun, Hyang-Min; Lee, Chan; Lee, Sun Young; Kim, Inho; Oh, Yu-Kyoung

    2003-01-01

    To increase the potency of DNA vaccines, we constructed genetic fusion vaccines encoding antigen, secretion signal, and/or chemokine RANTES. The DNA vaccines encoding secreted hepatitis B surface antigen (HBsAg) were constructed by inserting HBsAg gene into an expression vector with an endoplasmic reticulum (ER)-targeting secretory signal sequence. The plasmid encoding secretory HBsAg (pER/HBs) was fused to cDNA of RANTES, generating pER/HBs/R. For comparison, HBsAg genes were cloned into pVAX1 vector with no signal sequence (pHBs), and further linked to the N-terminus of RANTES (pHBs/R). Immunofluorescence study showed the cytoplasmic localization of HBsAg protein expressed from pHBs and pHBs/R, but not from pER/HBs and pER/HBs/R at 48 h after transfection. In mice, RANTES-fused DNA vaccines more effectively elicited the levels of HBsAg-specific IgG antibodies than pHBs. All the DNA vaccines induced higher levels of IgG 2a rather than IgG 1 antibodies. Of RANTES-fused vaccines, pER/HBs/R encoding the secreted fusion protein revealed much higher humoral and CD8 + T cell-stimulating responses compared to pHBs/R. These results suggest that the immunogenicity of DNA vaccines could be enhanced by genetic fusion to a secretory signal peptide sequence and RANTES

  9. Hepatitis B surface antigen titer is a good indicator of durable viral response after entecavir off-treatment for chronic hepatitis B.

    Science.gov (United States)

    Lee, Han Ah; Seo, Yeon Seok; Park, Seung Woon; Park, Sang Jung; Kim, Tae Hyung; Suh, Sang Jun; Jung, Young Kul; Kim, Ji Hoon; An, Hyunggin; Yim, Hyung Joon; Yeon, Jong Eun; Byun, Kwan Soo; Um, Soon Ho

    2016-09-01

    Clear indicators for stopping antiviral therapy in chronic hepatitis B (CHB) patients are not yet available. Since the level of hepatitis B surface antigen (HBsAg) is correlated with covalently closed circular DNA, the HBsAg titer might be a good indicator of the off-treatment response. This study aimed to determine the relationship between the HBsAg titer and the entecavir (ETV) off-treatment response. This study analyzed 44 consecutive CHB patients (age, 44.6±11.4 years, mean±SD; men, 63.6%; positive hepatitis B envelope antigen (HBeAg) at baseline, 56.8%; HBV DNA level, 6.8±1.3 log 10 IU/mL) treated with ETV for a sufficient duration and in whom treatment was discontinued after HBsAg levels were measured. A virological relapse was defined as an increase in serum HBV DNA level of >2000 IU/mL, and a clinical relapse was defined as a virological relapse with a biochemical flare, defined as an increase in the serum alanine aminotransferase level of >2 × upper limit of normal. After stopping ETV, virological relapse and clinical relapse were observed in 32 and 24 patients, respectively, during 20.8±19.9 months of follow-up. The cumulative incidence rates of virological relapse were 36.2% and 66.2%, respectively, at 6 and 12 months, and those of clinical relapse were 14.3% and 42.3%. The off-treatment HBsAg level was an independent factor associated with clinical relapse (hazard ratio, 2.251; 95% confidence interval, 1.076-4.706; P =0.031). When patients were grouped according to off-treatment HBsAg levels, clinical relapse did not occur in patients with an off-treatment HBsAg level of ≤2 log 10 IU/mL (n=5), while the incidence rates of clinical relapse at 12 months after off-treatment were 28.4% and 55.7% in patients with off-treatment HBsAg levels of >2 and ≤3 log 10 IU/mL (n=11) and >3 log 10 IU/mL (n=28), respectively. The off-treatment HBsAg level is closely related to clinical relapse after treatment cessation. A serum HBsAg level of response in CHB

  10. Hepatitis B surface antigen titer is a good indicator of durable viral response after entecavir off-treatment for chronic hepatitis B

    Directory of Open Access Journals (Sweden)

    Han Ah Lee

    2016-09-01

    Full Text Available Background/Aims Clear indicators for stopping antiviral therapy in chronic hepatitis B (CHB patients are not yet available. Since the level of hepatitis B surface antigen (HBsAg is correlated with covalently closed circular DNA, the HBsAg titer might be a good indicator of the off-treatment response. This study aimed to determine the relationship between the HBsAg titer and the entecavir (ETV off-treatment response. Methods This study analyzed 44 consecutive CHB patients (age, 44.6±11.4 years, mean±SD; men, 63.6%; positive hepatitis B envelope antigen (HBeAg at baseline, 56.8%; HBV DNA level, 6.8±1.3 log10 IU/mL treated with ETV for a sufficient duration and in whom treatment was discontinued after HBsAg levels were measured. A virological relapse was defined as an increase in serum HBV DNA level of >2000 IU/mL, and a clinical relapse was defined as a virological relapse with a biochemical flare, defined as an increase in the serum alanine aminotransferase level of >2 × upper limit of normal. Results After stopping ETV, virological relapse and clinical relapse were observed in 32 and 24 patients, respectively, during 20.8±19.9 months of follow-up. The cumulative incidence rates of virological relapse were 36.2% and 66.2%, respectively, at 6 and 12 months, and those of clinical relapse were 14.3% and 42.3%. The off-treatment HBsAg level was an independent factor associated with clinical relapse (hazard ratio, 2.251; 95% confidence interval, 1.076–4.706; P=0.031. When patients were grouped according to off-treatment HBsAg levels, clinical relapse did not occur in patients with an off-treatment HBsAg level of ≤2 log10 IU/mL (n=5, while the incidence rates of clinical relapse at 12 months after off-treatment were 28.4% and 55.7% in patients with off-treatment HBsAg levels of >2 and ≤3 log10 IU/mL (n=11 and >3 log10 IU/mL (n=28, respectively. Conclusion The off-treatment HBsAg level is closely related to clinical relapse after treatment

  11. Near-surface and bulk behavior of Ag in SiC

    International Nuclear Information System (INIS)

    Xiao, H.Y.; Zhang, Y.; Snead, L.L.; Shutthanandan, V.; Xue, H.Z.; Weber, W.J.

    2012-01-01

    Highlights: ► Ag release from SiC poses problems in safe operation of nuclear reactors. ► Near-surface and bulk behavior of Ag are studied by ab initio and ion beam methods. ► Ag prefers to adsorb on the surface rather than in the bulk SiC. ► At high temperature Ag desorbs from the surface instead of diffusion into bulk SiC. ► Surface diffusion may be a dominating mechanism accounting for Ag release from SiC. - Abstract: The diffusive release of fission products, such as Ag, from TRISO particles at high temperatures has raised concerns regarding safe and economic operation of advanced nuclear reactors. Understanding the mechanisms of Ag diffusion is thus of crucial importance for effective retention of fission products. Two mechanisms, i.e., grain boundary diffusion and vapor or surface diffusion through macroscopic structures such as nano-pores or nano-cracks, remain in debate. In the present work, an integrated computational and experimental study of the near-surface and bulk behavior of Ag in silicon carbide (SiC) has been carried out. The ab initio calculations show that Ag prefers to adsorb on the SiC surface rather than in the bulk, and the mobility of Ag on the surface is high. The energy barrier for Ag desorption from the surface is calculated to be 0.85–1.68 eV, and Ag migration into bulk SiC through equilibrium diffusion process is not favorable. Experimentally, Ag ions are implanted into SiC to produce Ag profiles buried in the bulk and peaked at the surface. High-temperature annealing leads to Ag release from the surface region instead of diffusion into the interior of SiC. It is suggested that surface diffusion through mechanical structural imperfection, such as vapor transport through cracks in SiC coatings, may be a dominating mechanism accounting for Ag release from the SiC in the nuclear reactor.

  12. Controlled synthesis and photocatalytic properties of rhombic dodecahedral Ag3PO4 with high surface energy

    International Nuclear Information System (INIS)

    Xie, Yao; Huang, Zhaohui; Zhang, Zhijie; Zhang, Xiaoguang; Wen, Ruilong; Liu, Yangai; Fang, Minghao; Wu, Xiaowen

    2016-01-01

    Graphical abstract: The high amount of rhombic dodecahedral Ag 3 PO 4 particles with a high exposure of the {110} facets and high surface energy (the surface energy of the {110} facets was 1.31 J/m 2 , greater than that of the {100} facet (1.12 J/m 2 ).) exhibited excellent photocatalytic activity. - Highlights: • High contents of rhombic dodecahedral Ag 3 PO 4 photocatalysts are prepared. • Excessive EG can destroy the morphology of Ag 3 PO 4 in synthesis process. • The rhombic dodecahedral Ag 3 PO 4 exhibits high surface energy. • High surface energy implies high photocatalytic activity. - Abstract: In this study, a series of Ag 3 PO 4 photocatalysts with different contents of rhombic dodecahedral particles were prepared in one pot by a facile, novel hydrothermal method using ethylene glycol (EG), which served as both a morphology modifier and reducing agent. The effects of EG content on the morphologies of Ag 3 PO 4 photocatalysts were discussed. The photocatalytic activity of the Ag 3 PO 4 photocatalysts was evaluated by the degradation of methylene blue trihydrate under visible-light irradiation. With the use of 0.8% EG in the reaction solvent, the sample exhibited excellent photocatalytic activity, attributed to the high amount of rhombic dodecahedral Ag 3 PO 4 particles with a high exposure of the {110} facets and high surface energy. The surface energy of the {110} facets was 1.31 J/m 2 , greater than that of the {100} facet (1.12 J/m 2 ). However, with 1% EG in the reaction solvent, although the Ag 3 PO 4 photocatalysts were composed of a majority of rhombic dodecahedral Ag 3 PO 4 particles, tiny Ag particles formed from Ag + under the action of EG attached on the surface of the sample decreased the absorption of visible light, resulting in low photocatalytic activity.

  13. Hepatocellular carcinoma. A study of 50 autopsy cases with detection of hepatitis B surface antigen in fixed tissues.

    Science.gov (United States)

    Perez-Barrios, A; Colina-Ruizdelgado, F; Gallego, I; Martinez-Tello, F J

    1983-03-01

    Fifty patients who died of hepatocellular carcinoma (HCC) were autopsied at the Ciudad Sanitaria "1 degree de Octubre" and the Hospital de la Cruz Roja (Madrid) from 1974 to 1980. Formalin fixed paraffin-embedded autopsy tissue of liver and tumor from the 50 HCC and liver tissue from 50 liver cirrhosis (LC) and from 50 autopsy of non cirrhotic control cases were examined for the presence of cytoplasmic hepatitis B surface antigen (HBsAg). The study was carried out using orcein staining, immunoperoxidase technique (IP) and indirect immunofluorescence (IF). In livers with HCC the HBsAg was detected in the cytoplasm of the hepatocytes in 10 cases (20%) with the orcein staining and in 11 (22%) with the IP and IF techniques. In one case (2%) HBsAg was found in the cytoplasm of tumor cells with the three methods--In four cases (8%) of LC and 2 (4%) control cases cytoplasmic positive cells were found. In 41 patients with HCC HBsAg was studied in the serum by radio-immunoassay (RIA) (13 cases) and immunodiffussion (28 cases). 5 patients (12,1%) were positive and 36 (72%) were negative. In the 5 serum positive HBsAg HCC the staining methods for cytoplasmic HBsAg were positive (100%). In 36 serum negative HBsAg HCC the staining method were positive in 2 cases. The results let us to conclude that HBV is a probable important etiologic factor of HCC in our milieu. 54% of the patients with HCC had a previous history of alcohol abuse; however, histologic features compatible with an alcoholic etiology were found in only 5 cases. Nevertheless we consider that the described histopathologic findings do not exclude excess alcohol consumption as a possible etiologic factor for HCC in our series.

  14. Approaches for Controlled Ag+ Ion Release: Influence of Surface Topography, Roughness, and Bactericide Content.

    Science.gov (United States)

    Sukhorukova, I V; Sheveyko, A N; Shvindina, N V; Denisenko, E A; Ignatov, S G; Shtansky, D V

    2017-02-01

    Silver is the most famous bactericidal element known from ancient times. Its antibacterial and antifungal effects are typically associated with the Ag ionization and concentration of Ag + ions in a bacterial culture. Herein we thoroughly studied the influence of surface topography and roughness on the rate of Ag + ion release. We considered two types of biocompatible and bioactive TiCaPCON-Ag films with 1 and 2 at. % of Ag and nine types of Ti surfaces with an average roughness varying in the range from 5.4 × 10 -2 to 12.6 μm and different topographic features obtained through polishing, sandblasting, laser treatment, and pulsed electrospark deposition. It is demonstrated that the Ag + ion release rates do not depend on the Ag content in the films as the main parameter, and it is other factors, such as the state of Ag agglomeration, surface topography and roughness, as well as kinetics of surface oxidation, that play a critical role. The obtained results clearly show a synergistic effect of the Ag content in the film and surface topography and roughness on Ag + ion release. By changing the surface topographical features at a constant content of bactericidal element, we showed that the Ag + ion release can be either accelerated by 2.5 times or almost completely suppressed. Despite low Ag + ion concentration in physiological solution (antibacterial effect already after 3 h of immersion in E. coli bacterial culture. Thus, our results open up new possibilities for the production of cost-effective, scalable, and biologically safe implants with pronounced antibacterial characteristics for future applications in the orthopedic field.

  15. An oil-in-water self-assembly synthesis, characterization and photocatalytic properties of nano Ag@AgCl surface-sensitized K2Ti4O9

    International Nuclear Information System (INIS)

    Liang, Yinghua; Lin, Shuanglong; Liu, Li; Hu, Jinshan; Cui, Wenquan

    2014-01-01

    Highlights: • The plasmatic Ag@AgCl surface-sensitized K 2 Ti 4 O 9 composite photocatalysts. • Ag@AgCl greatly increased visible light absorption for K 2 Ti 4 O 9 . • The photocatalysts exhibited enhanced photocatalytic dye degradation. - Abstract: Nano-sized plasmonic Ag@AgCl surface-sensitized K 2 Ti 4 O 9 composite photocatalysts (hereafter designated as Ag@AgCl/K 2 Ti 4 O 9 ) was synthesized via a facile oil-in-water self-assembly method. The photocatalytic activity of the prepared materials for RhB (Rhodamine B) degradation was examined under visible light irradiation. The results reveal that the size of Ag@AgCl, which evenly dispersed on the surface of K 2 Ti 4 O 9 , distributes about 20–50 nm. The UV–vis diffuse reflectance spectra indicate that Ag@AgCl/K 2 Ti 4 O 9 samples have a significantly enhanced optical absorption in 380–700 nm. The photocatalytic activities of the Ag@AgCl/K 2 Ti 4 O 9 samples increase first and then decrease with increasing amount of loading Ag@AgCl and the Ag@AgCl(20 wt.%)/K 2 Ti 4 O 9 sample exhibits the best photocatalytic activity and 94.47% RhB was degraded after irradiation for 2 h. Additionally, studies performed using radical scavengers indicated that O 2 · − and Cl 0 acted as the main reactive species. The electronic interaction was systematically studied and confirmed by the photo-electrochemical measurements

  16. Frequency of anti-HCV, Hbsag and related risk factors in pregnant women at Nishtar Hospital, Multan

    International Nuclear Information System (INIS)

    Taseer, I.H.; Ishaq, F.; Hussain, L.; Safdar, S.; Mirbahar, A.M.; Faiz, S.A.

    2010-01-01

    Background: Viral hepatitis is a global issue. Among the hepatitis viruses hepatitis B and C are important in South Asia including Pakistan. There are various modes of transmission of these viruses. Vertical transmission is also gaining importance. Antepartum screening for HBV and HCV would help the infected women for appropriate antiviral therapy at appropriate time as well as for taking proper care of the newborns. The present study was designed to see the frequency of HBsAg and anti-HCV in pregnant women at Nishtar Hospital, Multan. Methods: This was a cross-sectional study carried out using non-probability purposive sampling technique. The period of the study was from June 2006 to August 2007. Five hundred (500) pregnant women attending outpatient department of Gynaecology and Obstetrics were included. Informed consent was taken. A specially designed proforma was filled in. Anti-HCV and HBsAg were tested by device method. Data were analyzed on SPSS-11. Results: Out of 500 pregnant women 35 (7.00%) were found to be anti-HCV positive and 23 (4.60%) were positive for HBsAg. Mean age was 26.7+-4.8 years. Majority of the patients 263 (52.60%) were in the age group 26-35 years. 138 (27.60%) women were nulliparous and 282 (56.40%) were para 1-4 and anti-HCV and HBsAg were common in this parity group. Only 80 (16.00%) women were para 5 or more. All anti-HCV and HBsAg positive women were house-wives. Most of them were belonging to rural areas having poor socio-economic status. Among 35 anti-HCV positive women, 20 (57.14%) had history of previous surgery, while 13 (37.14%) had history of multiple injections, 5 (14.28%) received blood transfusion, 4 (11.42%) had ear/nose piercing while tattooing was seen in only 2 (5.71%). Among 23 HBsAg positive women, 10 (43.47%) had history of previous surgery. History of multiple injections was present in 6 (26.08%) patients, 4 (17.39%) patients had history of blood transfusion, tattooing, ear/nose piercing, history of dental

  17. Localized Surface Plasmon on 6H SiC with Ag Nanoparticles

    DEFF Research Database (Denmark)

    Wei, Yi; Fadil, Ahmed; Ou, Haiyan

    2017-01-01

    Silver (Ag) nanoparticles (NPs) were deposited on the surface of bulk Nitrogen-Boron co-doped 6H silicon carbide (SiC), and the Ag NPs were observed to induce localized surface plasmons (LSP) resonances on the SiC substrate, which was expected to improve the internal quantum efficiency (IQE...... of an Ag nanoparticle on the SiC substrate, it is predicted that when the diameter of the cross section on the xy plane of the Ag nanoparticle is greater than 225 nm, the LSP starts to enhance the PL intensity. With implementation of a 3rd order exponential decay fitting model to the TRPL results...

  18. Quantitative Measurement of Serum Hepatitis B Surface Antigen Using an Immunoradiometric Assay in Chronic Hepatitis B

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyun Woo; Lee, Ho Young; Kim, Seog Gyun; Kim, Won; Jung, Wong Jin; Kang, Keon Wook; Chung, June Key; Lee, Myung Chul; Lee, Dong Soo [Seoul National Univ. Seoul (Korea, Republic of)

    2011-03-15

    Measurement of serum hepatitis B virus surface antigen (HBsAg) levels is important for the management of chronic hepatitis D patients in terms of monitoring response to antiviral therapy. This study aimed to evaluate the diagnostic performance of a new diagnostic kit, which quantitatively measures serum HBsAg level using an immunoradiometric assay (IRMA) based method. Measurements were compared with those obtained using a chemiluminescent microparticle immunoassay (CMIA) based method. The blood samples of 96 patients with chronic hepatitis B were used in this study. Copy numbers of serum hepatitis B virus (HBV) DNA were determined in 23 of these samples. The correlation between and the concordance of IRMA and CMIA results were determined using Pearson's correlation coefficients. P values of 0.05 were considered to be statistically significant throughout. Laboratory diagnoses based on CMIA. Furthermors, serum HBsAg levels by IRMA were found to be highly correlated with those determined by CMIA (correlation coefficient R{sup 2=}0.838, P<0.001). Serum HBsAg level and serum HBV DNA copies were found to be linearly related by both methods (R{sup 2=}0.067, P=0.316 by IRMA, and R{sup 2=}0.101, P=0.215 by CMIA). The diagnostic performance of the investigated IRMA method of determining HBsAg levels was found to be comparable with that of a CMIA based method in chronic hepatitis B patients.

  19. Construction and expression of hepatitis B surface antigen escape variants within the "a" determinant by site directed mutagenesis.

    Science.gov (United States)

    Golsaz Shirazi, Forough; Amiri, Mohammad Mehdi; Mohammadi, Hamed; Bayat, Ali Ahmad; Roohi, Azam; Khoshnoodi, Jalal; Zarnani, Amir Hassan; Jeddi-Tehrani, Mahmood; Kardar, Gholam Ali; Shokri, Fazel

    2013-09-01

    The antibody response to hepatitis B surface antigen (HBsAg) controls hepatitis B virus infection. The "a" determinant of HBsAg is the most important target for protective antibody response, diagnosis and immunoprophylaxis. Mutations in this area may induce immune escape mutants and affect the performance of HBsAg assays. To construct clinically relevant recombinant mutant forms of HBsAg and assessment of their reactivity with anti-HBs monoclonal antibodies (MAbs). Wild type (wt) and mutant (mt) HBsAg genes were constructed by site directed mutagenesis and SEOing PCR. The amplified genes were inserted into pCMV6-neo plasmid and transfected in CHO cell line. The expression of wt- and mtHBsAg was assessed by commercial ELISA assays and stable cells were established and cloned by limiting dilution. The recombinant mutants were further characterized using a panel of anti-HBs monoclonal antibodies (MAbs) and the pattern of their reactivity was assessed by ELISA. Ten HBsAg mutants having single mutation within the "a" determinant including P120E, T123N, Q129H, M133L, K141E, P142S, D144A, G145R, N146S and C147S together with a wt form were successfully constructed and expressed in CHO cells. Reactivity of anti-HBs MAbs with mtHBsAgs displayed different patterns. The effect of mutations on antibody binding differed depending on the amino acid involved and its location within the ''a'' determinant. Mutation at amino acids 123 and 145 resulted in either complete loss or significant reduction of binding to all anti-HBs MAbs. Our panel of mtHBsAgs is a valuable tool for assessment of the antibody response to HBV escape mutants and may have substantial implications in HBV immunological diagnostics.

  20. Low thermal emissivity surfaces using AgNW thin films

    Science.gov (United States)

    Pantoja, Elisa; Bhatt, Rajendra; Liu, Anping; Gupta, Mool C.

    2017-12-01

    The properties of silver nanowire (AgNW) films in the optical and infrared spectral regime offer an interesting opportunity for a broad range of applications that require low-emissivity coatings. This work reports a method to reduce the thermal emissivity of substrates by the formation of low-emissivity AgNW coating films from solution. The spectral emissivity was characterized by thermal imaging with an FLIR camera, followed by Fourier transform infrared spectroscopy. In a combined experimental and simulation study, we provide fundamental data of the transmittance, reflectance, haze, and emissivity of AgNW thin films. Emissivity values were finely tuned by modifying the concentration of the metal nanowires in the films. The simulation models based on the transfer matrix method developed for the AgNW thin films provided optical values that show a good agreement with the measurements.

  1. Controlled preparation of Ag nanoparticle films by a modified photocatalytic method on TiO{sub 2} films with Ag seeds for surface-enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Xin; Pan, Lujun, E-mail: lpan@dlut.edu.cn; Li, Shuai; Wang, Qiao; Qin, Jun; Huang, Yingying

    2016-02-15

    Graphical abstract: - Highlights: • Uniform Ag nanoparticle films were synthesized by a modified photocatalytic method on TiO{sub 2} films with Ag seeds for surface-enhanced Raman scattering. • This modified photocatalytic method combine the advantages of the spurting method (high nucleation density) and the traditional photocatalytic method (suitable particle size). • The Raman enhancement of as-prepared Ag NP films was calculated by finite-difference time-domain to validate the experiment data. - Abstract: Uniform Ag nanoparticle (NP) films were synthesized by a modified photocatalytic method on TiO{sub 2} films with Ag seeds for surface-enhanced Raman scattering, which combine the advantages of the spurting method (high nucleation density) and the traditional photocatalytic method (suitable particle size). The Ag seeds were prepared by magnetron sputtering with different time, which would adjust the distribution and transfer of electrons on the surface of TiO{sub 2} film in the process of photocatalytic reduction. The distribution and morphology of Ag NP films can be adjusted by the sputtering time and the UV irradiation time. The Raman enhancement of as-prepared Ag NP films was calculated by finite-difference time-domain to validate the experiment data. It is found that the Ag NP films synthesized on TiO{sub 2} films with suitable pre-deposited Ag seeds exhibit a much higher Raman enhancement activity than the optimum Ag NP film synthesized directly on the TiO{sub 2} film without Ag seeds.

  2. CD205-TLR9-IL-12 axis contributes to CpG-induced oversensitive liver injury in HBsAg transgenic mice by promoting the interaction of NKT cells with Kupffer cells.

    Science.gov (United States)

    Hou, Xin; Hao, Xiaolei; Zheng, Meijuan; Xu, Congfei; Wang, Jun; Zhou, Rongbin; Tian, Zhigang

    2017-08-01

    Gut-derived bacterial products contribute to liver inflammation and injury during chronic hepatitis B virus infection; however, the underlying mechanisms remain obscure. In this study, hepatitis B surface antigen transgenic (HBs-Tg) mice and their wild-type (WT) control C57BL/6 mice were injected with CpG-oligodeoxynucleotides (ODNs) to mimic the translocation of gut microbial products into the systemic circulation. We found that, compared with the WT mice, the HBs-Tg mice were oversensitive to CpG-ODN-induced liver injury, which was dependent on natural killer T (NKT) cells. CpG-ODN injection enhanced the expression of Fas ligand (FasL) on NKT cells. In addition, hepatocytes from the HBs-Tg mice expressed higher levels of Fas than did those from the WT mice, which was further augmented by CpG-ODN. Interaction of Fas and FasL was involved in the cytotoxicity of NKT cells against hepatocytes in the HBs-Tg mice. Moreover, Kupffer cells in the HBs-Tg mice expressed higher levels of CD205 and produced greater amounts of interleukin (IL)-12 than did those in the WT mice. Finally, the depletion of Kupffer cells, neutralization of IL-12 or specific silencing of CD205 on Kupffer cells significantly inhibited CpG-ODN-induced liver injury and NKT activation in the HBs-Tg mice. Our data suggest that CD205-expressing Kupffer cells respond to CpG-ODNs and subsequently release IL-12 to promote NKT cell activation. Activated NKT cells induce liver damage through the Fas signaling pathway in HBs-Tg mice.

  3. Formation of Ag nanowires on graphite stepped surfaces. A DFT study

    Science.gov (United States)

    Ambrusi, Rubén E.; García, Silvana G.; Pronsato, María E.

    2015-01-01

    We investigate the feasibility of obtaining silver nanowires on graphite stepped surfaces theoretically, using density functional theory calculations. Three layer slabs are used to model graphite surfaces with and without defects. Adsorption energies for Ag atoms on graphite surfaces were calculated showing the preference of Ag adatoms to locate on the steps, forming linear structures like nanowires. An analysis of the charge densities and projected densities of states for different structures is also performed.

  4. Antibacterial and microstructure properties of titanium surfaces modified with Ag-incorporated nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guangzhong; Cheng, Li [State Key Laboratory of Porous Metal Materials, Northwest Institute for Nonferrous Metal Research (China); Yang, Hui-lin [Department of Orthopaedics, Wuxi People' s Hospital, Nanjing Medical University, Jiangsu Province (China); Zhao, Quan-ming, E-mail: abc8385@163.com [Department of Orthopaedics, The First Affiliated Hospital of Soochow University, Suzhou (China)

    2016-07-15

    Although titanium (Ti) and its alloys have been widely used as implants in clinical settings, failures still occur mainly due to poor bioactivity and implant-associated infections. Here, we coated Ti implants with TiO{sub 2} nanotubes (TNTs) incorporated with the antibacterial agent Ag to produce Ag-TNTs, through anodization in AgNO{sub 3} and xenon light irradiation. We characterized surface morphology and composition of the coating with scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. We investigated surface topography of the coatings by atomic force microscopy (AFM) operated in the tapping mode. The results indicate that Ag was successfully doped onto the TNTs, and that the nanoparticles were mainly distributed on the surface of TNTs. Finally, our antibacterial experiments reveal that Ag-TNTs on Ti implants exhibit excellent antibacterial activities, which promises to have significant clinical applications as implants. (author)

  5. Hepatitis B viral DNA decline at loss of HBeAg is mainly explained by reduced cccDNA load--down-regulated transcription of PgRNA has limited impact.

    Science.gov (United States)

    Malmström, Sebastian; Larsson, Simon B; Hannoun, Charles; Lindh, Magnus

    2012-01-01

    Quantification of hepatitis B virus (HBV) DNA and surface antigen (HBsAg) serum levels have become increasingly important for the assessment of clinical stage and response to treatment for chronic hepatitis B. Effective immune clearance results in reduction of viremia by 4-5 log units and HBsAg levels by 2 log, but these processes are not well understood. Thus, it is uncertain to what extent mechanisms that inhibit transcription of the pregenomic RNA (pgRNA), an RNA intermediate, contribute to suppression of viremia. Likewise, it is unclear if transcriptional regulation is important for the excessive production of surface antigen (HBsAg) that is a hallmark of HBV infection. HBV RNA and cccDNA were quantified in 19 liver biopsies from patients with chronic HBV infection, as well as in transfected Huh7.5 cells and in PLC/PRF/5 cells carrying integrated HBV genome. Patients negative for HBeAg had 2.15 log lower levels of cccDNA in liver tissue, 4.84 log lower serum levels of HBV DNA and 1.45 log lower serum levels of HBsAg, than HBeAg-positive patients. The pgRNA in liver tissue correlated strongly with cccDNA (R(2) = 0.87, ploss of HBeAg was mainly explained by reduced cccDNA load in the liver, whereas the contribution of down-regulation of pgRNA transcription was relatively small. Enhanced transcription of S-RNA does not explain excessive production of HBsAg.

  6. Hepatitis B Surface AntigenemiaAmong Transfused Children with ...

    African Journals Online (AJOL)

    Patients with sickle cell anaemia (SCA), a common haematological disorder inNigeria,may have complications that require blood transfusion, thus exposing them to the risk. Objective: To determine the prevalence of hepatitis B surface antigen (HBsAg) among transfused childrenwith SCAin Enugu. Subjects and Method: ...

  7. Prevalence of hepatitis B surface antigen seropositivity among HIV ...

    African Journals Online (AJOL)

    Hepatitis B surface antigen (HBsAg) was tested for using a one step lateral flow rapid chromatographic immunoassay (Acumen labs and diagnostic centre, Bangalore, India) and HIV 1/2 was tested using two kits, Determine (made by Abbot, Japan for Inverness Medical, Japan). Results: A total of 2018 subjects were studied ...

  8. Hepatitis B Vaccination Coverage and Prevalence of Hepatitis B Surface Antigen Among Children in French Polynesia, 2014.

    Science.gov (United States)

    Patel, Minal K; Le Calvez, Evelyne; Wannemuehler, Kathleen; Ségalin, Jean-Marc

    2016-06-01

    French Polynesia is considered to be moderately endemic for chronic hepatitis B virus infection, with an estimated 3% of the population having hepatitis B surface antigen (HBsAg). From 1990 to 1992, a 3-dose hepatitis B vaccination series was introduced into the routine infant immunization schedule in French Polynesia, including a birth dose (BD). In 2014, a nationally representative 2-stage cluster survey was undertaken to evaluate the impact of the vaccination program on HBsAg prevalence among school children (∼6 years of age) in Cours Préparatoire (CP). Documented vaccination data were reviewed for all eligible children; children with consent were tested for HBsAg with a rapid point-of-care test. In total, 1,660 students were identified; 1,567 (94%) had vaccination data for review and 1,196 (72%) participated in the serosurvey. Three-dose vaccination coverage was 98%, while timely BD coverage, defined as a dose administered within 24 hours of life, was 89%. Receipt of the second and third doses was often delayed, with 75% and 55% receiving a second and third dose within 1 month of the recommended age, respectively. No children tested positive for HBsAg. French Polynesia's vaccination program has achieved high coverage and an HBsAg seroprevalence of 0% (0-0.5%) among CP school children, but timeliness of vaccination could be improved. © The American Society of Tropical Medicine and Hygiene.

  9. Ag Active Sites, Surface Intermediates and Hydrogen Function at decane-SCR-Nox over Ag/Alumina

    Czech Academy of Sciences Publication Activity Database

    Sazama, Petr; Wichterlová, Blanka; Sobalík, Zdeněk; Nováková, Jana; Dědeček, Jiří

    2007-01-01

    Roč. 172, - (2007), s. 501-504 ISSN 0167-2991. [Tokyo Conference in Advanced Catalytic Science and Technology /5./. Tokyo, 23.07.2007-28.07.2007] R&D Projects: GA AV ČR 1ET400400413; GA ČR GD203/03/H140 Institutional research plan: CEZ:AV0Z40400503 Keywords : SCR- NOx * Ag active sites * surface intermediates Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.307, year: 2005

  10. Quantitative hepatitis B surface antigen combined with hepatitis B e antigen as sustained virological response predictors during extended therapy with Peginterferon alfa-2a for hepatitis B e antigen-positive chronic hepatitis B.

    Science.gov (United States)

    Chen, Jie; Zhang, Dong-Hua; Xu, Cheng-Run; Zhu, Ming-Yu; Yang, Zhi-Tao; Gong, Qi-Ming; Yu, De-Min; Zhang, Xin-Xin

    2015-11-01

    The best strategy for chronic hepatitis B patients with poor response to 48 weeks of Peginterferon-based therapy has been controversial and the predictive value of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and hepatitis B virus (HBV) DNA levels for determining the sustained virological response (SVR) of these patients is uncertain. To optimize management of these patients and evaluate the use of these serobiomarkers to predict SVR. Eighty-one patients with an unsatisfactory response after 48 weeks of Peginterferon-based therapy were treated with extended Peginterferon therapy with or without nucleo(s) tide analogues (NAs), for a total of 96 weeks of Peginterferon treatment. HBsAg, HBeAg and HBV DNA levels were measured serially during the treatment and follow-up. Twenty-six of 81 patients (32.1%) attained SVR during the 72-week follow-up. The SVR rate was not statistically different between groups receiving 1-year prolongation of Peginterferon with or without NAs. The serum HBsAg cut-off of 1800IU/mL at week 48 had area under curve (AUC) of 0.727, and the serum HBsAg cut-off of 1500IU/mL, combined with HBeAg loss at week 72, had AUC of 0.753 to predict SVR during the follow-up. In conclusion, extended treatment with Peginterferon with or without NAs for patients with unsatisfactory response after 48 weeks of Peginterferon-based therapy is a promising strategy to achieve SVR, and quantitative serum HBsAg at week 48 and HBsAg level combined with HBeAg loss at week 72 of therapy can predict SVR to prolongation therapy with Peginterferon. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Surface structural, morphological, and catalytic studies of homogeneously dispersed anisotropic Ag nanostructures within mesoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Sareen, Shweta [Thapar University, School of Chemistry and Biochemistry (India); Mutreja, Vishal [Maharishi Markandeshwar University, Department of Chemistry (India); Pal, Bonamali; Singh, Satnam, E-mail: ssingh@thapar.edu [Thapar University, School of Chemistry and Biochemistry (India)

    2016-11-15

    Highly dispersed anisotropic Ag nanostructures were synthesized within the channels of 3-aminopropyltrimethoxysilane (APTMS)-modified mesoporous SBA-15 for catalyzing the reduction of p-dinitrobenzene, p-nitrophenol, and p-nitroacetophenone, respectively. A green templating process without involving any reducing agent, by varying the amount (1–10 wt.%) of Ag loading followed by calcination at 350 °C under H{sub 2} led to change in the morphology of Ag nanoparticles from nanospheres (~7–8 nm) to nanorods (aspect ratio ~12–30 nm) without any deformation in mesoporous sieves. In comparison to white bare SBA-15, gray-colored samples were formed with Ag impregnation exhibiting absorption bands at 484 and 840 nm indicating the formation of anisotropic Ag nanostructures within mesoporous matrix. TEM and FE-SEM micrographs confirmed the presence of evenly dispersed Ag nanostructures within as well as on the surface of mesoporous matrix. AFM studies indicated a small decrease in the average roughness of SBA-15 from 20.59 to 19.21 nm for 4 wt.% Ag/m-SBA-15, illustrating the encapsulation of majority of Ag nanoparticles in the siliceous matrix and presence of small amount of Ag nanoparticles on the mesoporous support. Moreover, due to plugging of mesopores with Ag, a significant decrease in surface area from 680 m{sup 2}/g of SBA-15 to 385 m{sup 2}/g was observed. The Ag-impregnated SBA-15 catalyst displayed superior catalytic activity than did bare SBA-15 with 4 wt.% Ag-loaded catalyst exhibiting optimum activity for selective reduction of p-nitrophenol to p-aminophenol (100 %), p-nitroacetophenone to p-aminoacetophenone (100 %), and p-dinitrobenzene to p-nitroaniline (87 %), with a small amount of p-phenylenediamine formation.

  12. SEROPREVALENCE OF HBsAg AMONG PATIENTS WITH FEBRILE ...

    African Journals Online (AJOL)

    USER

    2015-06-01

    Mazie et al., 2002; Paulyn et al., 2010; Okonkwo et al., 2010). The burden pose on health of individual made it necessary to carry out routing screening before blood transfusion in health facilities and more importantly to reduce its.

  13. Prevalence of HBsAg Among Prospective Blood Donors and ...

    African Journals Online (AJOL)

    methods for the measurement of catalytic concentration of enzymes. Part 5.IFCC method for alkaline phosphatase (orthophosphoric-monoester phosphohydrolase, alkaline optimum, EC 3.1.3.1). Journal of Clinical Chemistry and Clinical. Biochemistry, 21: 731-48. Weichselbaum, T.E. (1946). Biuret method of serum total.

  14. Recombinant hepatitis B surface antigen production in Aspergillus niger: evaluating the strategy of gene fusion to native glucoamylase

    CSIR Research Space (South Africa)

    James, ER

    2012-10-01

    Full Text Available and maltose), although residual glucose accumulation in the mid-exponential phase reduced HBsAg production. HBsAg production in starchbased cultures may be improved further by optimization of the rates of starch hydrolysis by glucoamylase and subsequent... in cultivation significantly affected HBsAg production levels through induction of the glucoamylase promoter. The highest specific HBsAg production was observed during growth on inducing substrates of starch and its degradation products (maltodextrin...

  15. The Murine Humoral Immune Response to Hepatitis B Surface Antigen: Idiotype Network Pathways.

    Science.gov (United States)

    Schick, Michael Roy

    Recognition of a wide spectrum in disease outcomes following Hepatitis B Virus (HBV) infection has led to the suggestion that individual differences may be due to characteristics of the immune response. HBV, a hepatotropic virus, is not directly cytopathic to the host hepatocytes but the cellular damage which does not occur may be due to the host's own immune response. It is this variety in immune response capabilities following natural infection or vaccination which led to the present study in which the murine humoral immune response to hepatitis B surface antigen (HBsAg) was examined. Following immunization with purified HBsAg an anti-HBs response could be detected in 19 inbred strains of mice. The response, which varied among the strains, was linked to the major histocompatibility complex (MHC). Among high responders to HBsAg were two strains in which a poor response to a single epitope could be detected. Although quantitatively serum from these strains resembled serum from other high responders, there was a major difference in the qualitative aspects. Included within this study was the role of idotype networks within the murine anti-HBs response. By directly targeting HBsAg-specific B cells within the framework of an idiotype network by an Ab-2, it was possible to circumvent T cell-dependent regulation of an immune response. In each of five inbred strains of mice immunized with a polyclonal rabbit Ab-2 an Ab-3 population with HBsAg-specificity (Ab -1^') was induced. These mice were also immunized with HBsAg resulting in a higher anti-HBs response as compared to HBsAg immunization alone in all of the strains tested except for one. The response in this strain, normally a low responder to HBsAg, indicated that the mechanisms for genetic restriction of the anti -HBs response was still active, although it was not apparent during anti-Id immunization. The effects of an anti-Id on the murine antibody response to HBsAg may lead to insights on the presence of idiotype

  16. Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition.

    Science.gov (United States)

    Lu, Xiong; Zhang, Bailin; Wang, Yingbo; Zhou, Xianli; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio; Ding, Yonghui; Leng, Yang

    2011-04-06

    Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and l-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices.

  17. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Tao [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Liu, Yong [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Zhu, Yan, E-mail: zhuyan@kmust.edu.cn [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Yang, De-Quan, E-mail: dequan.yang@gmail.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Sacher, Edward [Regroupement Québécois de Matériaux de Pointe, Department of Engineering Physics, École Polytechnique de Montréal, Case Postale 6079, succursale Centre-Ville, Montréal, Québec H3C 3A7 (Canada)

    2017-07-31

    Highlights: • A two-step process has been developed to enhance the adhesion of immobilized Ag NPs to the PET surface. • The method is simple, easy to use and low-cost for mass production. • The increased density of active sites (−OH, −CH=O and COOH) at the PET surface, after plasma treatment, permits increased reaction with 3-aminopropyltriethoxysilane (APTES). • The presence of APTES with high surface density permits −NH{sub 2}-Ag complex formation, increasing the adhesion of the Ag NPs. - Abstract: Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (−OH, −CH=O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose −NH{sub 2} groups were then able to form a bonding complex with the Ag NPs.

  18. High hepatitis B surface antigen levels predict insignificant fibrosis in hepatitis B e antigen positive chronic hepatitis B.

    Directory of Open Access Journals (Sweden)

    Wai-Kay Seto

    Full Text Available INTRODUCTION: There is no data on the relationship between hepatitis B surface antigen (HBsAg levels and liver fibrosis in hepatitis B e antigen (HBeAg-positive patients with chronic hepatitis B (CHB. METHODS: Serum HBsAg and HBV DNA levels in HBeAg-positive CHB patients with liver biopsies were analyzed. The upper limit of normal (ULN of alanine aminotransferase (ALT was 30 and 19 U/L for men and women respectively. Histologic assessment was based on Ishak fibrosis staging for fibrosis and Knodell histologic activity index (HAI for necroinflammation. RESULTS: 140 patients (65% male, median age 32.7 years were recruited. 56 (40% had ALT ≤2×ULN. 72 (51.4% and 42 (30% had fibrosis score ≤ 1 and necroinflammation grading ≤ 4 respectively. Patients with fibrosis score ≤ 1, when compared to patients with fibrosis score >1, had significantly higher median HBsAg levels (50,320 and 7,820 IU/mL respectively, p<0.001. Among patients with ALT ≤2×ULN, serum HBsAg levels achieved an area under receiver operating characteristic curve of 0.869 in predicting fibrosis score ≤ 1. HBsAg levels did not accurately predict necroinflammation score. HBsAg ≥ 25,000 IU/mL was independently associated with fibrosis score ≤ 1 (p=0.025, odds ratio 9.042.Using this cut-off HBsAg level in patients with ALT ≤2×ULN, positive and negative predictive values for predicting fibrosis score ≤ 1 were 92.7% and 60.0% respectively. HBV DNA levels had no association with liver histology. CONCLUSION: Among HBeAg-positive patients with ALT ≤2×ULN, high serum HBsAg levels can accurately predict fibrosis score ≤ 1, and could potentially influence decisions concerning treatment commencement and reduce the need for liver biopsy.

  19. Radioimmunoassay of surface antigen and core antibody of hepatitis B virus. Comparison of kits AUSRIA/CORE; AUSRIA II-125 and CORAB

    Energy Technology Data Exchange (ETDEWEB)

    Kselikova, M.; Urbankova, J. (Ustav Hematologie a Krevni Transfuze, Prague (Czechoslovakia))

    1984-08-01

    The sensitivity is compared of determination of surface antigen HBsAg and nuclear antibody HBcAb of the hepatitis B virus using kits for separate (AUSRIA II-125, CORAB) and simultaneous (AUSRIAsup(R)/CORE) determinations of third generation tests in selected samples of medical personnel, HBsAg carriers, patients at a dialysis centre, blood donors and in sera of HBsAg carriers diluted in steps from 4x10/sup -2/ to 4x10/sup -7/. HBsAg is always determined using the RIA technique, HBcAb is determined using the technique of radioimmunoassay with the CORAB kit and with the AUSRIA sup(R)/CORE kit using enzymeimmunoassay. The sensitivity of determination using the AUSRIA sup(R)/CORE kit is at least as good for both investigated indicators of the hepatitis B virus and that obtained using separate determination of HBsAg (AUSRIA II-125) and HBcAb (CORAB), this also using modified photocolorimetric determination. Only one AUSRIA/sup R//CORE kit was available for the investigation and the informative character of the report is emphasized.

  20. Behavior of Ag nanoparticles in soil: Effects of particle surface coating, aging and sewage sludge amendment

    International Nuclear Information System (INIS)

    Whitley, Annie R.; Levard, Clément; Oostveen, Emily; Bertsch, Paul M.; Matocha, Chris J.; Kammer, Frank von der; Unrine, Jason M.

    2013-01-01

    This study addressed the relative importance of particle coating, sewage sludge amendment, and aging on aggregation and dissolution of manufactured Ag nanoparticles (Ag MNPs) in soil pore water. Ag MNPs with citrate (CIT) or polyvinylpyrrolidone (PVP) coatings were incubated with soil or municipal sewage sludge which was then amended to soil (1% or 3% sludge (w/w)). Pore waters were extracted after 1 week and 2 and 6 months and analyzed for chemical speciation, aggregation state and dissolution. Ag MNP coating had profound effects on aggregation state and partitioning to pore water in the absence of sewage sludge, but pre-incubation with sewage sludge negated these effects. This suggests that Ag MNP coating does not need to be taken into account to understand fate of AgMNPs applied to soil through biosolids amendment. Aging of soil also had profound effects that depended on Ag MNP coating and sludge amendment. -- Highlights: •Silver nanoparticle coating affects fate in unamended soils. •Citrated coated silver nanoparticles could be found in pore water for up to six months. •Pre-incubation of silver nanoparticles in sewage sludge negated effects of surface coating. •Weathered or reprecipitated particles found in pore water for up to two months in sludge amended soils. •Particle surface coating, sewage sludge amendment and aging all have important impacts. -- Behavior of manufactured silver nanoparticles in soil depends on surface coating, contact with sewage sludge, and aging

  1. Virus-like particle production with yeast: ultrastructural and immunocytochemical insights into Pichia pastoris producing high levels of the Hepatitis B surface antigen

    Directory of Open Access Journals (Sweden)

    Adnan Ahmad

    2011-06-01

    Full Text Available Abstract Background A protective immune response against Hepatitis B infection can be obtained through the administration of a single viral polypeptide, the Hepatitis B surface antigen (HBsAg. Thus, the Hepatitis B vaccine is generated through the utilization of recombinant DNA technology, preferentially by using yeast-based expression systems. However, the polypeptide needs to assemble into spherical particles, so-called virus-like particles (VLPs, to elicit the required protective immune response. So far, no clear evidence has been presented showing whether HBsAg assembles in vivo inside the yeast cell into VLPs or later in vitro during down-stream processing and purification. Results High level production of HBsAg was carried out with recombinant Pichia pastoris using the methanol inducible AOX1 expression system. The recombinant vaccine was isolated in form of VLPs after several down-stream steps from detergent-treated cell lysates. Search for the intracellular localization of the antigen using electron microscopic studies in combination with immunogold labeling revealed the presence of HBsAg in an extended endoplasmic reticulum where it was found to assemble into defined multi-layered, lamellar structures. The distance between two layers was determined as ~6 nm indicating that these lamellas represent monolayers of well-ordered HBsAg subunits. We did not find any evidence for the presence of VLPs within the endoplasmic reticulum or other parts of the yeast cell. Conclusions It is concluded that high level production and intrinsic slow HBsAg VLP assembly kinetics are leading to retention and accumulation of the antigen in the endoplasmic reticulum where it assembles at least partly into defined lamellar structures. Further transport of HBsAg to the Golgi apparatus is impaired thus leading to secretory pathway disfunction and the formation of an extended endoplasmic reticulum which bulges into irregular cloud-shaped formations. As VLPs were

  2. Hollow Au/Ag nanostars displaying broad plasmonic resonance and high surface-enhanced Raman sensitivity

    Science.gov (United States)

    Garcia-Leis, Adianez; Torreggiani, Armida; Garcia-Ramos, Jose Vicente; Sanchez-Cortes, Santiago

    2015-08-01

    Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars. The size, shape, and composition of Ag as well as their optical properties were studied by extinction spectroscopy, hyperspectral dark field microscopy, transmission and scanning electron microscopy (TEM and SEM), and energy dispersive X-ray spectroscopy (EDX). Finally, the surface-enhanced Raman scattering (SERS) activity of these HNS was investigated by using thioflavin T, a biomarker of the β-amyloid fibril formation, responsible for Alzheimer's disease. Lucigenin, a molecule displaying different SERS activities on Au and Ag, was also used to explore the presence of these metals on the NP surface. Thus, a relationship between the morphology, plasmon resonance and SERS activity of these new NPs was made.Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars

  3. Multiple surface antigen mutations in five blood donors with occult hepatitis B virus infection

    NARCIS (Netherlands)

    Zaaijer, H. L.; Torres, P.; Ontañón, A.; Ponte, L. González; Koppelman, M. H. G. M.; Lelie, P. N.; Hemert, F. J. van; Boot, H. J.

    2008-01-01

    Occult hepatitis B virus (HBV) infection is characterized by the presence of HBV DNA while the HBV surface antigen (HBsAg) remains undetectable. The HBV genomes in five asymptomatic blood donors with occult HBV infection and low viremia ( <10 to 1,000 HBV DNA copies/mL, genotype D) were studied. An

  4. Theoretical investigation of bulk ordering and surface segregation in Ag-Pd and other isoelectornic alloys

    Science.gov (United States)

    Ruban, A. V.; Simak, S. I.; Korzhavyi, P. A.; Johansson, B.

    2007-02-01

    Bulk ordering in Ag-Pd and other isoelectronic alloys is investigated theoretically by a number of first-principles techniques. The electronic structure and total energy have been calculated by the Green’s function Korringa-Kohn-Rostocker and full-potential plane wave methods. The effective cluster interactions of the Ising-type Hamiltonian have been obtained by the screened generalized perturbation method. They reveal a complex concentration-dependent ordering behavior in these alloys due to band filling and Fermi surface effects. In particular we show that long-period superstructures are gradually stabilized by a great number of relatively weak long-range effective pair- and three-site interactions, which can be seen as “collective” effect. A similar complex concentration dependence is also found for surfaces of Ag-Pd alloys. The surface composition of the (111) and (100) surface of Ag75Pd25 , Ag50Pd50 , and Ag33Pd67 alloys have been then investigated by the surface Green’s function technique and the screened generalized perturbation method for the effective interactions of the Ising-type Hamiltonian and the grand canonical Monte Carlo method for statistical thermodynamic simulations at finite temperatures. We compare our results with experimental data and other theoretical calculations.

  5. A Better Antiviral Efficacy Found in Nucleos(tide Analog (NA Combinations with Interferon Therapy than NA Monotherapy for HBeAg Positive Chronic Hepatitis B: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Wei Wei

    2015-08-01

    Full Text Available Background: The clinical efficacy of nucleos(tide analogues (NAs combined with interferon (IFN therapy vs. NAs monotherapy for chronic hepatitis B (CHB remains inconclusive. The aim of this meta-analysis was to determine whether the NAs plus IFN regimen offers synergistic efficacy that justifies the cost and burden of such a combination therapy in CHB patients. Methods: Related publications covering the period of 1966 to July 2014 were identified through searching MEDLINE, EMBASE, Cochrane library, Chinese Biomedical Literature Database, WANFANG, and CNKI database. A total of 17 studies were enrolled, including 6 in English and 11 in Chinese. Then, we established a final list of studies for the meta-analysis by systematically grading the quality and eligibility of the identified individual studies. We used hepatitis B antigen (HBeAg loss, HBV-DNA undetectable rate, HBeAg seroconversion, hepatitis B surface antigen (HBsAg loss, HBsAg seroconversion, and histological score at the end of treatment for efficacy evaluation. A quantitative meta-analysis (Review Manager, Version 5.1.0 was performed to assess the differences between NAs and IFN combination therapy and NAs monotherapy. Results: Our analysis demonstrated that HBeAg loss (RR = 1.73, 95% CI = 1.32–2.26, p < 0.001, HBV-DNA undetectable rate (RR = 1.58, 95% CI = 1.22–2.04, p < 0.001, HBeAg seroconversion (RR = 1.68, 95% CI = 1.36–2.07, p < 0.001, and HBsAg loss (RR = 2.51, 95% CI = 1.32–4.75, p < 0.001 in the combination therapy group were significantly higher than those in the monotherapy group. However, there were no significant differences in HBsAg seroconversion (RR = 4.25, 95% CI = 0.62–29.13, p = 0.14, sustained virological response rates, and biochemical response rates observed between the two groups. The results showed that the combination therapy group had more improved HBV histology than the NAs monotherapy group (RR = 1.14, 95% CI = 0.93–1.39, p = 0.22. Conclusions: NAs

  6. Protective effect of hepatitis B vaccine combined with two-dose hepatitis B immunoglobulin on infants born to HBsAg-positive mothers.

    Science.gov (United States)

    Zou, Huaibin; Chen, Yu; Duan, Zhongping; Zhang, Hua

    2011-01-01

    Despite the use of hepatitis B (HB) vaccine and hepatitis B immunoglobulin (HBIG), a portion of infants are still non- or low-responders, or even immunoprophylaxis failure. We aimed to determine the immune response in the infants from the mothers being positive for hepatitis B surface antigen (HBsAg), by which the infants received three doses of HB vaccine in combination with two-dose 200 IU HBIG injections. In this retrospective study, 621 infants from HBsAg-positive mothers in Beijing YouAn Hospital between January 2008 and December 2009 were included. All the infants were given three doses of 10 µg HB vaccine (at 0, 1 and 6 months of age) and two-dose of 200 IU HBIG (at birth and in 2 weeks of age). Serum HBsAg and antibody to HBsAg (anti-HBs) in all the infants were determined at 7 months of age. Of the 621 infants, 2.9% were immunoprophylaxis failure (positive for HBsAg), 1.4% were non-responders (anti-HBs undetectable), 95.7% were responders. The 594 responders could be categorized into three subsets, 22 were 10 to 99 IU/L for anti-HBs levels, 191 were 100 to 999 IU/L, and 381 were ≥1000 IU/L. The immunoprophylaxis failure rate was at 0% and 5.2% for the infants of HBeAg-negative and HBeAg-positive mothers(Pvaccination. Through vaccination by three doses of HB and two-dose of HBIG, majority of the infants (95.7%) achieved a protective level of anti-HBs at 7 months of age. Maternal HBeAg-positive and HBV DNA detectable were associated with the immunoprophylaxis failure, but not contribute to the non- or low-response to HB vaccination.

  7. Surface-supported Ag islands stabilized by a quantum size effect: Their interaction with small molecules relevant to ethylene epoxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Dahai [Iowa State Univ., Ames, IA (United States)

    2013-05-15

    This dissertation focuses on how QSE-stabilized, surface-supported Ag nanoclusters will interact with ethylene or oxygen. Experiments are performed to determine whether the QSE-mediated Ag islands react differently toward adsorption of ethylene or oxygen, or whether the adsorption of these small molecules will affect the QSE-mediated stability of Ag islands. Studies of the interaction of oxygen with Ag/Si(111)-7×7 were previously reported, but these studies were performed at a low Ag coverage where 3D Ag islands were not formed. So the study of such a system at a higher Ag coverage will be a subject of this work. The interaction of ethylene with Ag/Si(111)-7×7, as well as the interaction of oxygen with Ag/NiAl(110) are also important parts of this study.

  8. Correlation between two chemiluminescence based assays for quantification of hepatitis B surface antigen in patients with chronic hepatitis B infection

    Directory of Open Access Journals (Sweden)

    E Gupta

    2015-01-01

    Full Text Available Purpose: Hepatitis B surface Antigen (HBsAg is the hallmark in diagnosing hepatitis B virus (HBV infection. In India many commercial assays are available for detection of HBsAg but very few can measure it quantitatively. The present study presents the comparative evaluation of two methods and their correlation with serum HBsAg in chronic hepatitis B (CHB patients. Materials and Methods: Consecutive patients of CHB were included and there HBsAg levels were measured by two methods: (i Elecsys, Roche Diagnostics, a qualitative assay and (ii Architect, Abbott Diagnostics, a quantitative assay. The HBV DNA was measured by real-time polymerase chain reaction (qPCR. Results: Total of 136 patients were included in the study and there was a significant overall correlation between both the assays (correlation coefficient [r] = 0.83; P < 0.001. Assays correlated well with each other across all subgroups of CHB: treatment naοve (r = 0.73; P < 0.001, n = 32, on treatment (r = 0.56; P < 0.05, n = 104, hepatitis Be (HBe antigen positive (r = 0.67; P < 0.001, n = 62 and anti-HBe positive (r = 0.61; P < 0.05, n = 74 group. On correlation with serum HBV DNA, Architect assay demonstrated good correlation (r = 0.73; P < 0.001, n = 136 as compared to the Elecsys assay (r = 0.27; P = 0.068, n = 136. Architect HBsAg QT assay (A1 also correlated well with HBV DNA in the treatment naοve group (r = 0.69; P < 0.001, n = 32. Conclusions: Our study hence proved that both the assays are comparable and a simple qualitative assay with in-house modification can be used easily for quatitation of HBsAg in clinical samples.

  9. Bifunctional Ag@Pd-Ag Nanocubes for Highly Sensitive Monitoring of Catalytic Reactions by Surface-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Li, Jumei; Liu, Jingyue; Yang, Yin; Qin, Dong

    2015-06-10

    We report a route to the facile synthesis of Ag@Pd-Ag nanocubes by cotitrating Na2PdCl4 and AgNO3 into an aqueous suspension of Ag nanocubes at room temperature in the presence of ascorbic acid and poly(vinylpyrrolidone). With an increase in the total titration volume, we observed the codeposition of Pd and Ag atoms onto the edges, corners, and side faces of the Ag nanocubes in a site-by-site fashion. By maneuvering the Pd/Ag ratio, we could optimize the SERS and catalytic activities of the Ag@Pd-Ag nanocubes for in situ SERS monitoring of the Pd-catalyzed reduction of 4-nitrothiophenol by NaBH4.

  10. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Science.gov (United States)

    Shen, Tao; Liu, Yong; Zhu, Yan; Yang, De-Quan; Sacher, Edward

    2017-07-01

    Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (sbnd OH, sbnd CHdbnd O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose sbnd NH2 groups were then able to form a bonding complex with the Ag NPs.

  11. Chlorine-induced modifications in the electronic structure of Ag surfaces: a metastable deexcitation spectroscopy and photoemission comparative study

    CERN Document Server

    Pasquali, L; Canepa, M; Staicu-Casagrande, E M; Esaulov, V A

    2003-01-01

    Surface-sensitive spectroscopic techniques, namely metastable deexcitation spectroscopy (MDS) and ultraviolet photoemission (UPS), have been applied to investigate the effects of chlorine chemisorption on the electronic properties (surface density of states and charge density) of Ag(100), Ag(110) and Ag(111) surfaces. Initial stages of chemisorption, up to the formation of a saturated Cl overlayer, have been examined. In particular, MDS permitted us to observe at low Cl gas exposure a progressive depletion of the Ag (5s) charge due to transfer and bonding with Cl atoms. From both MDS and UPS it was possible to observe the development of Cl (3p) bonding and anti-bonding states, the amount of their splitting increasing with coverage. Differences between chemisorption at the three surfaces have been noticed and they have been justified in terms of the different adatom packing and possible formation of small AgCl clusters (especially for the Ag(111) surface).

  12. Chlorine-induced modifications in the electronic structure of Ag surfaces: a metastable deexcitation spectroscopy and photoemission comparative study

    International Nuclear Information System (INIS)

    Pasquali, L; Nannarone, S; Canepa, M; Staicu-Casagrande, E M; Esaulov, V A

    2003-01-01

    Surface-sensitive spectroscopic techniques, namely metastable deexcitation spectroscopy (MDS) and ultraviolet photoemission (UPS), have been applied to investigate the effects of chlorine chemisorption on the electronic properties (surface density of states and charge density) of Ag(100), Ag(110) and Ag(111) surfaces. Initial stages of chemisorption, up to the formation of a saturated Cl overlayer, have been examined. In particular, MDS permitted us to observe at low Cl gas exposure a progressive depletion of the Ag (5s) charge due to transfer and bonding with Cl atoms. From both MDS and UPS it was possible to observe the development of Cl (3p) bonding and anti-bonding states, the amount of their splitting increasing with coverage. Differences between chemisorption at the three surfaces have been noticed and they have been justified in terms of the different adatom packing and possible formation of small AgCl clusters (especially for the Ag(111) surface)

  13. Performance evaluation of new automated hepatitis B viral markers in the clinical laboratory: two quantitative hepatitis B surface antigen assays and an HBV core-related antigen assay.

    Science.gov (United States)

    Park, Yongjung; Hong, Duck Jin; Shin, Saeam; Cho, Yonggeun; Kim, Hyon-Suk

    2012-05-01

    We evaluated quantitative hepatitis B surface antigen (qHBsAg) assays and a hepatitis B virus (HBV) core-related antigen (HBcrAg) assay. A total of 529 serum samples from patients with hepatitis B were tested. HBsAg levels were determined by using the Elecsys (Roche Diagnostics, Indianapolis, IN) and Architect (Abbott Laboratories, Abbott Park, IL) qHBsAg assays. HBcrAg was measured by using Lumipulse HBcrAg assay (Fujirebio, Tokyo, Japan). Serum aminotransferases and HBV DNA were respectively quantified by using the Hitachi 7600 analyzer (Hitachi High-Technologies, Tokyo, Japan) and the Cobas AmpliPrep/Cobas TaqMan test (Roche). Precision of the qHBsAg and HBcrAg assays was assessed, and linearity of the qHBsAg assays was verified. All assays showed good precision performance with coefficients of variation between 4.5% and 5.3% except for some levels. Both qHBsAg assays showed linearity from 0.1 to 12,000.0 IU/mL and correlated well (r = 0.9934). HBsAg levels correlated with HBV DNA (r = 0.3373) and with HBcrAg (r = 0.5164), and HBcrAg also correlated with HBV DNA (r = 0.5198; P < .0001). This observation could provide impetus for further research to elucidate the clinical usefulness of the qHBsAg and HBcrAg assays.

  14. Construction and characterization of calreticulin-HBsAg fusion gene recombinant adenovirus expression vector.

    Science.gov (United States)

    Ma, Chun-Ling; Wang, Gui-Bin; Gu, Run-Guo; Wang, Fang

    2010-06-28

    To generate recombinant adenoviral vector containing calreticulin (CRT)-hepatitis B surface antigen (HBsAg) fusion gene for developing a safe, effective and HBsAg-specific therapeutic vaccine. CRT and HBsAg gene were fused using polymerase chain reaction (PCR), endonuclease digestion and ligation methods. The fusion gene was cloned into pENTR/D-TOPO transfer vector after the base pairs of DNA (CACC) sequence was added to the 5' end. Adenoviral expression vector containing CRT-HBsAg fusion gene was constructed by homologous recombinantion. The human embryo kidney (HEK) 293A cells were transfected with linearized DNA plasmid of the recombinant adenoviral vector to package and amplify recombinant adenovirus. The recombinant adenovirus titer was characterized using the end-dilution assay. The expression of the CRT/HBsAg fusion protein in Ad-CRT/HBsAg infected 293A cells was detected by Western blotting. The CRT-HBsAg fusion gene was characterized by PCR and sequencing and its length and sequence were confirmed to be accurate. The CRT-HBsAg fusion gene recombinant pENTR/D-TOPO transfer vector was constructed. The recombinant adenoviral vector, Ad-CRT/HBsAg, was generated successfully. The titer of Ad-CRT/HBsAg was characterized as 3.9 x 10(11) pfu/mL. The CRT-HBsAg fusion protein was expressed by HEK 293A cells correctly. CRT/HBsAg fusion gene recombinant replication-defective adenovirus expression vector is constructed successfully and this study has provided an experimental basis for further studies of Hepatitis B virus gene therapy.

  15. Fabricating a Homogeneously Alloyed AuAg Shell on Au Nanorods to Achieve Strong, Stable, and Tunable Surface Plasmon Resonances

    KAUST Repository

    Huang, Jianfeng

    2015-08-13

    Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) can be useful in a corrosive environment for many applications including field-enhanced spectroscopies, plasmon-mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core–shell structured bimetallic nanorods (AuNR@AuAg) have well-mixed Au and Ag atoms in their shell without discernible domains. This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag-coated Au NRs (AuNR@Ag) and Au-coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable toward oxidative treatment. Specifically, AuNR@AuAg and AuNR@Ag exhibit similarly strong signals in surface-enhanced Raman spectroscopy that are some 30-fold higher than that of AuNR@Au. When incubated with a H2O2 solution (0.5 m), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (≈620–690 nm) by controlling the thickness of the AuAg alloy shell. The synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.

  16. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS).

    Science.gov (United States)

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-09-30

    Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C 3 N 4 (S-g-C 3 N 4 ) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C 3 N 4 /Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C 3 N 4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C 3 N 4 nanosheets, and induces a charge transfer from S-g-C 3 N 4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C 3 N 4 /Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C 3 N 4 /Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C 3 N 4 /Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.

  17. Simultaneous expression of growth hormone releasing hormone (GHRH) and hepatitis B surface antigen/somatostatin (HBsAg/SS) fusion genes in a construct in the skeletal muscle enhances rabbit weight gain.

    Science.gov (United States)

    Dai, Jian-wei; Liu, Song-cai; Hao, Lin-lin; Zhang, Yong-liang; Zhang, Qianqian; Ren, Xiao-hui; Jiang, Qing-yan

    2008-01-01

    Somatostatin (SS) and growth hormone-releasing hormone (GHRH) are synthesized and secreted by the hypothalamus, which can control the synthesis and secretion of the growth hormone (GH) from the hypophysis as well as regulate the GH concentrations in animals and humans. In this article, we describe the regulation of animal growth using plasmid DNA encoding both the GHRH gene and the SS gene fused with the hepatitis B surface antigen (HBsAg) gene. We constructed a series of expression plasmids to express the GHRH and HBsAg-SS fusion genes individually as well as collectively. The fusion gene and GHRH were successfully expressed in Chinese hamster ovary (CHO) cells, as proven by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting tests. Poly D, L-lactide-co-glycolic acid (PLGA) plasmid-encapsulating microspheres were prepared and injected intramuscularly into the leg skeletal muscles of rabbits. Weight gain/day and the levels of insulinlike growth factor-I (IGF-I), SS, and hepatitis B surface antibody (HBsAb) were monitored. During days 30 postinjection, increase in weight gain/day and IGF- I concentration and decrease in SS were observed in treatment groups. From days 15 to 30 postinjection, the weight gain/day significantly increased (P gain/day (P gain/day in rabbits.

  18. The molecular dynamic study of anharmonic effects at Cu(111) and Ag(111) surfaces in the presence of Cu- and Ag-trimer island

    International Nuclear Information System (INIS)

    Shah, Zulfiqar Ali; Hayat, Sardar Sikandar; Rehman, Z.; Bouafia, Farida

    2014-01-01

    The molecular dynamics (MD) technique based on semi-empirical potentials, is used to carry out the diffusion of Cu- and Ag-trimer on Cu- and Ag(111) surface at 300, 500 and 700 K temperatures. The constant energy MD simulation elaborates the anharmonic effects at the surface such as fissures, dislocations and vacancy creation, in the presence of island. The fissures and dislocations formed are in the range of 1.5–4 Å and 1–7 Å, respectively, from the island's position. The Cu and Ag islands both diffuse easily on Cu(111) surface, manipulate that the trend of diffusion is faster on Cu surface as compared to Ag surface. The process of breaking and opening of the island has also been observed. Moreover, a surface atom popped-up at 700 K by creating a vacancy near the Cu island on Ag surface. The rate of diffusion increases with the increase in temperature, both for homo- and hetero-cases.

  19. Luteolin-7-O-Glucoside Present in Lettuce Extracts Inhibits Hepatitis B Surface Antigen Production and Viral Replication by Human Hepatoma Cells in Vitro

    Directory of Open Access Journals (Sweden)

    Xiao-Xian Cui

    2017-12-01

    Full Text Available Hepatitis B virus (HBV infection is endemic in Asia and chronic hepatitis B (CHB is a major public health issue worldwide. Current treatment strategies for CHB are not satisfactory as they induce a low rate of hepatitis B surface antigen (HBsAg loss. Extracts were prepared from lettuce hydroponically cultivated in solutions containing glycine or nitrate as nitrogen sources. The lettuce extracts exerted potent anti-HBV effects in HepG2 cell lines in vitro, including significant HBsAg inhibition, HBV replication and transcription inhibition, without exerting cytotoxic effects. When used in combination interferon-alpha 2b (IFNα-2b or lamivudine (3TC, the lettuce extracts synergistically inhibited HBsAg expression and HBV replication. By using differential metabolomics analysis, Luteolin-7-O-glucoside was identified and confirmed as a functional component of the lettuce extracts and exhibited similar anti-HBV activity as the lettuce extracts in vitro. The inhibition rate on HBsAg was up to 77.4%. Moreover, both the lettuce extracts and luteolin-7-O-glucoside functioned as organic antioxidants and, significantly attenuated HBV-induced intracellular reactive oxygen species (ROS accumulation. Luteolin-7-O-glucoside also normalized ROS-induced mitochondrial membrane potential damage, which suggests luteolin-7-O-glucoside inhibits HBsAg and HBV replication via a mechanism involving the mitochondria. Our findings suggest luteolin-7-O-glucoside may have potential value for clinical application in CHB and may enhance HBsAg and HBV clearance when used as a combination therapy.

  20. Prognostic implications of recipient or donor hepatitis B seropositivity in thoracic transplantation: analysis of 426 hepatitis B surface antigen-positive recipients.

    Science.gov (United States)

    Manickam, P; Krishnamoorthi, R; Kanaan, Z; Gunasekaran, P K; Cappell, M S

    2014-08-01

    Prognostic data on survival of hepatitis B surface antigen-positive (HBsAg+) recipients and of hepatitis B core antibody-positive (HBcAb+) donors are limited in the thoracic transplantation (TT) cohort. Improved understanding of risks could potentially expand the recipient and donor pools. Post-hoc analysis of limited-access dataset of the United Network for Organ Sharing database from January 2000-September 2010 was performed. Analyses were performed for all TT, including single and bilateral lung, orthotopic heart, and simultaneous heart-lung transplants. The primary analyzed outcome was overall survival. A Cox proportional multivariate hazards model was used to adjust for significant risk predictors. Of 24,817 patients included, 426 recipients were HBsAg+, of whom 106 (25%) died during a mean follow-up of 3.6 years. On multivariate analysis, recipient HBsAg+ (hazard ratio [HR] = 0.88, 95% confidence interval [CI]: 0.69-1.32; P = 0.80), and donor HBcAb+ (HR = 0.91, 95% CI: 0.68-1.22; P = 0.53) were not associated with increased overall mortality in the entire TT cohort, with similar results for each individual transplant cohort. Unadjusted survival analysis using Kaplan-Meier curves in individual transplant cohorts did not show significant differences between HBsAg+ and HBsAg- recipients. No statistically significant differences were found between causes of mortality in the 2 groups. HBsAg+ status of recipients or HBcAb+ status of donors does not significantly affect overall survival of TT recipients. These data add to the scant literature on this subject and could potentially increase the donor and recipient pools. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Effect of Ag Doping on the Electronic Structure and Optical Properties of ZnO(0001 Surface

    Directory of Open Access Journals (Sweden)

    Xiang Qian

    2018-01-01

    Full Text Available Using first-principle calculations, the geometrical structure, the electronic and optical properties of Ag-doped ZnO(0001 surface have been investigated. We found that Ag-doped ZnO(0001 surface is more easily formed on the first layer. On the other hand, the doped surface has gradually become an equipotential body, showing obvious metallic characteristics. We found that a new peak appeared in the low energy region after Ag doping, which was mainly due to the electron transition between the two orbital levels of Ag-4d and O-2p.

  2. Relation between laboratory test results and histological hepatitis activity in individuals positive for hepatitis B surface antigen and antibodies to hepatitis B e antigen

    NARCIS (Netherlands)

    ter Borg, F.; ten Kate, F. J.; Cuypers, H. T.; Leentvaar-Kuijpers, A.; Oosting, J.; Wertheim-van Dillen, P. M.; Honkoop, P.; Rasch, M. C.; de Man, R. A.; van Hattum, J.; Chamuleau, R. A.; Reesink, H. W.; Jones, E. A.

    1998-01-01

    BACKGROUND: Hepatitis B surface antigen (HBsAg) and antibodies to hepatitis B e antigen (anti-HBe) commonly coexist, and laboratory tests are often requested to assess histological hepatitis activity. An optimum panel of tests has not been found and the usefulness of hepatitis B virus (HBV) DNA

  3. Enhancement in electrical conductivity of pastes containing submicron Ag-coated Cu filler with palmitic acid surface modification

    Science.gov (United States)

    Choi, Eun Byeol; Lee, Jong-Hyun

    2017-09-01

    The fabrication and applied use of submicron Ag-coated Cu (Cu@Ag) particles as a filler material for epoxy-based conductive pastes having the advantages of a lower material cost and antioxidation behavior were studied. Submicron Cu@Ag particles were successfully prepared and surface-modified using palmitic acid. Diffuse reflectance infrared Fourier transform spectroscopy and thermogravimetric differential scanning calorimetry results indicated the formation of an organic layer by the chemical interaction between the Cu@Ag surface and palmitic acid and the survival of the organic layer after treatment at 160 °C for 3 h in air. The printed pastes containing both commercial micron Cu@Ag flakes and the fabricated submicron Cu@Ag particles showed a greatly reduced electrical resistivity (4.68 × 10-4 Ω cm) after surface modification compared to an initial value of 1.85 × 10-3 Ω cm when cured.

  4. Effect of swift heavy ion Ag9+ irradiation on the surface morphology, structure and optical properties of AgGaS2 single crystals

    Science.gov (United States)

    Prabukanthan, P.; Asokan, K.; Kanjilal, D.; Dhanasekaran, R.

    2008-12-01

    AgGaS2 (AGS) single crystals grown by chemical vapor transport (CVT) method were irradiated with Ag9+ ions (120 MeV) with various ion fluences. The irradiation was carried out at room temperature (RT) and at liquid nitrogen temperature (LNT). A glancing angle x-ray diffraction (GAXRD) analysis reveals a huge lattice disorder at RT irradiation. This is observed from an increase in the full width at half maximum (FWHM) and a decrease in the intensity of the AGS (1 1 2) peak. However, there is no change in the FWHM of the (1 1 2) peak but the intensity slightly decreases at LNT irradiation. Also, AGS (3 0 3) peak is not observed for the samples irradiated with the fluences of 5 × 1013 and 1 × 1013 ions cm-2 at RT conditions. The GAXRD results show the decrease in degree of crystallinity upon ion irradiation at RT while there is not much degradation in crystallinity upon ion irradiation at LNT. But the LNT irradiation on AGS has its own effects. Atomic force microscope (AFM) studies show that the roughness of AGS increases on increasing the ion fluences at LNT and at RT. Also, it is found that there is an increase in the surface defects with fluences of Ag9+ ion irradiation when compared to pristine AGS. UV-visible transmission spectra show that the percentage of transmission and bandgap energy decrease with increasing ion fluences and also that the peaks are broadened at LNT and at RT. The photoluminescence (PL) spectra were analyzed as a function of irradiation ion fluences in the AGS crystals at RT. It has been found that the emission intensities of band-to-band transition decrease with increase of ion fluences at LNT and at RT.

  5. The relationship between HBcrAg and HBV reinfection in HBV related post-liver transplantation patients.

    Science.gov (United States)

    Urabe, Ayako; Imamura, Michio; Tsuge, Masataka; Kan, Hiromi; Fujino, Hatsue; Fukuhara, Takayuki; Masaki, Keiichi; Kobayashi, Tomoki; Ono, Atsushi; Nakahara, Takashi; Kawaoka, Tomokazu; Hiramatsu, Akira; Kawakami, Yoshiiku; Aikata, Hiroshi; Hayes, Clair Nelson; Maki, Noboru; Ohdan, Hideaki; Chayama, Kazuaki

    2017-03-01

    Post-transplant hepatitis B virus (HBV) reinfection is one of the major problems facing patients who undergo HBV-related liver transplantation (LT). We analyzed the clinical impact of serum hepatitis B core-related antigen (HBcrAg) on HBV reinfection in post-LT patients with HBV-related liver diseases. Serum hepatitis B surface antigen (HBsAg), HBV DNA, and HBcrAg were measured over time in 32 post-LT patients. Twenty-one out of 32 patients had HCC at LT. The effects of HBcrAg, hepatocellular carcinoma (HCC) recurrence, and HBs gene mutation on HBV reinfection and withdrawal from hepatitis B immune globulin (HBIG) were analyzed. Sixteen out of 32 patients (50 %) were positive for HBcrAg even though only six patients were thought to have experienced HBV reinfection based on reappearance of either HBV DNA or HBsAg during a median follow-up time of 75 months. Three of these six patients who became re-infected with HBV experienced HCC recurrence after LT. The HBV DNA reappearance rate was significantly higher in patients with HCC recurrence after LT (p HBV re-infected patients without HCC recurrence had HBs gene mutations G145R and G145A, respectively. Anti-HBs antibody development rate by HB vaccination was similar between HBcrAg-positive and negative patients (p = 0.325). HBV reinfection is more common than is usually considered based on conventional measurement of HBsAg and HBV DNA. HCC recurrence and mutations in the HBV S gene were associated with HBV reinfection after LT.

  6. Optical Properties of DLC:SiOx and Ag Multilayer Films: Surface Plasmon Resonance Effect

    Directory of Open Access Journals (Sweden)

    Arvydas ČIEGIS

    2016-11-01

    Full Text Available Diamond like carbon films containing silicon (DLC:SiOx and „conventional“ hydrogenated diamond like carbon (DLC films were deposited by direct ion beam using anode layer ion source. Ag films were grown by unbalanced direct current magnetron sputtering. Structure of DLC:SiOx films was investigated by Raman scattering spectroscopy. In the case of DLC:SiOx film deposited on Ag layer surface enhanced Raman scattering effect was observed. Optical properties of the different diamond like carbon and silver multilayers were studied. Annealing effects were investigated. Influence of the thickness of the diamond like carbon and Ag layers was investigated. Position of the plasmonic absorbance peak maximum of DLC:SiOx and multilayers in all cases was redshifted in comparison with “conventional” diamond like nanocomposite films containing silver nanoclusters. It was explained by increase of the Ag nanoparticle size and/or increased probability of the oxidation of the embedded Ag due to the higher amount of oxygen in DLC:SiOx film in comparison with “conventional” diamond like carbon film.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.13194

  7. Prevalence of Serologic Hepatitis B Markers in Blood Donors From Puebla, Mexico: The Association of Relatively High Levels of Anti-Core Antibodies With the Detection of Surface Antigen and Genomic DNA.

    Science.gov (United States)

    Sosa-Jurado, Francisca; Hilda Rosas-Murrieta, Nora; Guzman-Flores, Belinda; Perez Zempoaltecalt, Cintia; Patricia Sanchez Torres, Ana; Ramirez Rosete, Leticia; Bernal-Soto, Maribel; Marquez-Dominguez, Luis; Melendez-Mena, Daniel; Angel Mendoza Torres, Miguel; Teresa Lopez Delgado, Maria; Reyes-Leyva, Julio; Vallejo-Ruiz, Veronica; Santos-Lopez, Gerardo

    2016-06-01

    The hepatitis B virus (HBV) causes chronic hepatitis, hepatic cirrhosis, and hepatocellular carcinoma. Surface antigen (HBsAg) detection is a definitive test that can confirm HBV infection, while the presence of antibodies against the core protein (anti-HBc) suggests either a previous or ongoing infection or occult hepatitis B infection (OBI). The aim of the present study was to determine the prevalence of anti-HBc and HBsAg in blood donors. Further, the study aimed to estimate the anti-HBc level at which HBV DNA is detected in putative OBI cases, as well as to search for mutations in the "a" determinant associated with the non-detection of HBsAg in serum. We conducted a cross-sectional study from 2003-2009. The study included 120,552 blood donors from the state of Puebla, Mexico. Different commercial systems based on microparticles (enzymatic (MEIA) or chemiluminescent (CMIA)) were used to determine the HBsAg and anti-HBc levels. For the detection of HBV DNA, a nested polymerase chain reaction (nested PCR) was used and the genotypes were determined using Sanger sequencing. Of the 120,552 blood donors, 1437 (1.19%, 95% CI: 1.12 - 1.26) were reactive to anti-HBc, while 82 (0.066%, 95% CI: 0.053 - 0.079) were reactive to HBsAg. Some 156 plasma samples collected in 2009 from anti-HBc-positive/HBsAg-negative blood donors were submitted for HBV DNA detection in a search for probable OBI. Viral DNA was detected in 27/156 (17.3%, 95% CI: 11.5 - 23.1). Our results show an association between HBV DNA or HBsAg and anti-HBc S/CO levels ≥ 4.0. All DNA samples were identified as genotype H and some "a" determinant mutations were identified, although none corresponded to mutations previously reported to hinder the detection of HBsAg by commercial immunoassays. We observed that as the anti-HBc levels increase, there is a higher prevalence of the viral protein HBsAg in blood donors. Samples testing positive for HBV-DNA were seen to exhibit a ten-fold higher presence of anti

  8. Prevalence of Serologic Hepatitis B Markers in Blood Donors From Puebla, Mexico: The Association of Relatively High Levels of Anti-Core Antibodies With the Detection of Surface Antigen and Genomic DNA

    Science.gov (United States)

    Sosa-Jurado, Francisca; Hilda Rosas-Murrieta, Nora; Guzman-Flores, Belinda; Perez Zempoaltecalt, Cintia; Patricia Sanchez Torres, Ana; Ramirez Rosete, Leticia; Bernal-Soto, Maribel; Marquez-Dominguez, Luis; Melendez-Mena, Daniel; Angel Mendoza Torres, Miguel; Teresa Lopez Delgado, Maria; Reyes-Leyva, Julio; Vallejo-Ruiz, Veronica; Santos-Lopez, Gerardo

    2016-01-01

    Background The hepatitis B virus (HBV) causes chronic hepatitis, hepatic cirrhosis, and hepatocellular carcinoma. Surface antigen (HBsAg) detection is a definitive test that can confirm HBV infection, while the presence of antibodies against the core protein (anti-HBc) suggests either a previous or ongoing infection or occult hepatitis B infection (OBI). Objectives The aim of the present study was to determine the prevalence of anti-HBc and HBsAg in blood donors. Further, the study aimed to estimate the anti-HBc level at which HBV DNA is detected in putative OBI cases, as well as to search for mutations in the “a” determinant associated with the non-detection of HBsAg in serum. Patients and Methods We conducted a cross-sectional study from 2003–2009. The study included 120,552 blood donors from the state of Puebla, Mexico. Different commercial systems based on microparticles (enzymatic (MEIA) or chemiluminescent (CMIA)) were used to determine the HBsAg and anti-HBc levels. For the detection of HBV DNA, a nested polymerase chain reaction (nested PCR) was used and the genotypes were determined using Sanger sequencing. Results Of the 120,552 blood donors, 1437 (1.19%, 95% CI: 1.12 - 1.26) were reactive to anti-HBc, while 82 (0.066%, 95% CI: 0.053 - 0.079) were reactive to HBsAg. Some 156 plasma samples collected in 2009 from anti-HBc-positive/HBsAg-negative blood donors were submitted for HBV DNA detection in a search for probable OBI. Viral DNA was detected in 27/156 (17.3%, 95% CI: 11.5 - 23.1). Our results show an association between HBV DNA or HBsAg and anti-HBc S/CO levels ≥ 4.0. All DNA samples were identified as genotype H and some “a” determinant mutations were identified, although none corresponded to mutations previously reported to hinder the detection of HBsAg by commercial immunoassays. Conclusions We observed that as the anti-HBc levels increase, there is a higher prevalence of the viral protein HBsAg in blood donors. Samples testing positive

  9. A PILOT EXTERNAL QUALITY ASSURANCE STUDY OF TRANSFUSION SCREENING FOR HIV, HCV AND HBSAG IN TWELVE AFRICAN COUNTRIES

    Science.gov (United States)

    Bloch, Evan M; Shah, Avani; Kaidarova, Zhanna; Laperche, Syria; Lefrere, Jean-Jacques; van Hasselt, James; Zacharias, Peter; Murphy, Edward L

    2014-01-01

    Background and Objectives Serologic screening for the major transfusion transmissible viruses (TTV) is critical to blood safety and has been widely implemented. However, actual performance as measured by proficiency testing has not been well studied in Sub-Saharan Africa. Therefore, we conducted an external quality assessment of laboratories engaged in transfusion screening in the region. Materials and Methods Blinded test panels, each comprising 25 serum samples that were pedigreed for HIV, HBsAg, HCV and negative status, were sent to participating laboratories. The panels were tested using the laboratories’ routine donor screening methods and conditions. Sensitivity and specificity were calculated and multivariable analysis was used to compare performance against mode of testing, country and infrastructure. Results A total of 12 African countries and 44 laboratories participated in the study. The mean (range) sensitivities for HIV, HBsAg and HCV were 91.9% (14.3-100), 86.7% (42.9-100) and 90.1% (50-100), respectively. Mean specificities for HIV, HBsAg and HCV were 97.7%, 97% and 99.5% respectively. After adjusting for country and infrastructure, rapid tests had significantly lower sensitivity than enzyme immunoassays (EIA) for both HBsAg (p<0.0001) and HCV (p<0.05). Sensitivity also varied by country and selected infrastructure variables. Conclusion While specificity was high, sensitivity was more variable and deficient in a substantial number of testing laboratories. These findings underscore the importance of proficiency testing and quality control, particularly in Africa where TTV prevalence is high. PMID:25052195

  10. Seroprevalence of hepatitis B surface antigenemia and its effects on hematological parameters in pregnant women in Osogbo, Nigeria.

    Science.gov (United States)

    Kolawole, Olatunji M; Wahab, Abideen A; Adekanle, Daniel A; Sibanda, Timothy; Okoh, Anthony I

    2012-12-27

    The transmission of the hepatitis B virus (HBV) is parenteral, sexual and perinatal. Prevention of vertical transmission of HBV is extremely important because HBV infection in early life usually results in a chronic carrier State. A descriptive seroepidemiological study of hepatitis B virus and its effects on hematological parameters was investigated in pregnant women attending antenatal clinic of LAUTECH Teaching Hospital, Osogbo, Nigeria. 200 venous samples were subjected to full blood count and its sera were subjected to enzyme-linked immunosorbent assay for the detection of surface antigen of hepatitis B virus. Prevalence rate of 16.5% was obtained for hepatitis B surface antigen in pregnant women. The highest HBsAg prevalence rate recorded was 23.3% for pregnant women between aged 30-34 years while the lowest recorded was zero percent for those aged greater than 40 years. RBC, WBC, neutrophil, hemoglobin lymphocyte and platelet counts have no significant effects on HBsAg positivity of pregnant women (p=0.801). There was no significant difference in HBsAg positivity in relation to maternal age, gravidity, gestational age, family type, level of education and occupation (p=0.073). Among the potential risk factors, there was significant difference in HBsAg positivity in the pregnant women in relation to their history of HBV vaccination (p=0.039). We advocate universal free screening of pregnant women as the endemicity of HBV infections is thus being propagated.

  11. Hepatitis B Surface Antigen Seroprevalence among Children in Papua New Guinea, 2012–2013

    Science.gov (United States)

    Kitau, Russel; Sankar Datta, Siddhartha; Patel, Minal K.; Hennessey, Karen; Wannemuehler, Kathleen; Sui, Gerard; Lagani, William

    2015-01-01

    Approximately 8% of the population in Papua New Guinea (PNG) has chronic hepatitis B virus (HBV) infection. To decrease the burden of chronic HBV infection, a national 3-dose infant hepatitis B vaccination program was implemented starting in 1989, with a birth dose (BD) added to the schedule in 1992. To assess the impact of the hepatitis B vaccination program, we conducted a serosurvey among children born after vaccine introduction. During 2012–2013, a cross-sectional stratified four-stage cluster survey was conducted to estimate hepatitis B surface antigen (HBsAg) prevalence among children 4–6 years of age. We collected demographic data, vaccination history, and tested children for HBsAg. Of 2,133 participants, 2,130 children had vaccination data by either card or recall: 28% received a BD; 81% received ≥ 3 vaccine doses. Of 2,109 children providing a blood sample, 60 (2.3%) tested positive for HBsAg. This is the largest, most geographically diverse survey of hepatitis B vaccination and HBsAg seroprevalence done in PNG. Progress has been made in PNG toward the Western Pacific Regional goal to reduce the prevalence of chronic HBV infection to < 1% by 2017 among 5-year-old children. Vaccination efforts should be strengthened, including increasing BD coverage and completing the 3-dose series. PMID:25582692

  12. Coating of hydroxyapatite doped Ag on commercially pure titanium surface; Recobrimento de hidroxiapatita dopada com Ag sobre superficie de titanio comercialmente puro

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Jonas de Oliveira; Vercik, Luci Cristina de Oliveira; Rigo, Eliana Cristina da Silva, E-mail: jonasvieira@usp.br [Universidade de Sao Paulo (USP), SP (Brazil)

    2012-07-01

    This paper presents results of bioactive coating on commercially pure titanium surface (CpTi) doped with Ag ions. The coating consists of 3 steps, in step 1- surface chemical treatment of the samples with NaOH, step 2 - immersing the substrate in question in a sodium silicate solution (SS) to the nucleation and step 3 - reimmersion these substrates in synthetic solution that simulates the blood serum for precipitation and growth of apatite layer. After the coating step the AgNO{sub 3} substrates were immersed in solutions with concentrations of 20 ppm and 100 ppm at 37 ° C for 48h. The substrates were characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR) and X-ray diffraction (XRD). By the results verified the formation of an apatite layer with aspects of cells, on the surface of CpTi. The increase in Ag concentration causes an increase in Ag amount doped in apatite layer. With the results we concluded that it is possible to obtain an apatite layer on a metal surface as the CpTi doped with Ag ions.

  13. Computational investigation of CO adsorbed on Aux, Agx and (AuAg)x nanoclusters (x = 1 - 5, 147) and monometallic Au and Ag low-energy surfaces*

    Science.gov (United States)

    Gould, Anna L.; Catlow, C. Richard A.; Logsdail, Andrew J.

    2018-02-01

    Density functional theory calculations have been performed to investigate the use of CO as a probe molecule for the determination of the structure and composition of Au, Ag and AuAg nanoparticles. For very small nanoclusters (x = 1 - 5), the CO vibrational frequencies can be directly correlated to CO adsorption strength, whereas larger 147-atom nanoparticles show a strong energetic preference for CO adsorption at a vertex position but the highest wavenumbers are for the bridge positions. We also studied CO adsorption on Au and Ag (100) and (111) surfaces, for a 1 monolayer coverage, which proves to be energetically favourable on atop only and bridge positions for Au (100) and atop for Ag (100); vibrational frequencies of the CO molecules red-shift to lower wavenumbers as a result of increased metal coordination. We conclude that CO vibrational frequencies cannot be solely relied upon in order to obtain accurate compositional analysis, but we do propose that elemental rearrangement in the core@shell nanoclusters, from Ag@Au (or Au@Ag) to an alloy, would result in a shift in the CO vibrational frequencies that indicate changes in the surface composition. Contribution to the Topical Issue "Shaping Nanocatalysts", edited by Francesca Baletto, Roy L. Johnston, Jochen Blumberger and Alex Shluger.Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjb/e2017-80280-7

  14. Natural Killer Cell Characteristics in Patients With Chronic Hepatitis B Virus (HBV) Infection Are Associated With HBV Surface Antigen Clearance After Combination Treatment With Pegylated Interferon Alfa-2a and Adefovir

    NARCIS (Netherlands)

    Stelma, Femke; de Niet, Annikki; Tempelmans Plat-Sinnige, Marjan J.; Jansen, Louis; Takkenberg, R. Bart; Reesink, Hendrik W.; Kootstra, Neeltje A.; van Leeuwen, Ester M. M.

    2015-01-01

    The role of natural killer (NK) cells in the process of hepatitis B virus (HBV) surface antigen (HBsAg) clearance and whether their phenotype is related to treatment outcome in patients with chronic hepatitis B are currently unknown. Patients with chronic hepatitis B (HBV DNA load, >17 000 IU/mL)

  15. Ammonia synthesis on Au modified Fe(111) and Ag and Cu modified Fe(100) surfaces

    DEFF Research Database (Denmark)

    Lytken, Ole; Waltenburg, Hanne Neergaard; Chorkendorff, Ib

    2003-01-01

    In order to investigate any influence of steps and possible positive effects of making surface alloys the ammonia synthesis has been investigated over Au modified Fe(111) and Ag and Cu modified Fe(100) single crystals in the temperature range 603-773 K, using a system combining ultra-high vacuum...... and a high-pressure cell. Ammonia was synthesized from a stoichiometric (N-2:3H(2)) gas mixture at a pressure of 2 bar. By deposition of small amounts of An, the ammonia production activity of the Fe(1 1 1) surface can be enhanced. More important, for the gold modified surface, the reaction order in ammonia...

  16. Scattering of atomic and molecular ions from single crystal surfaces of Cu, Ag and Fe

    International Nuclear Information System (INIS)

    Zoest, J.M. van.

    1986-01-01

    This thesis deals with analysis of crystal surfaces of Cu, Ag and Fe with Low Energy Ion scattering Spectroscopy (LEIS). Different atomic and molecular ions with fixed energies below 7 keV are scattered by a metal single crystal (with adsorbates). The energy and direction of the scattered particles are analysed for different selected charge states. In that way information can be obtained concerning the composition and atomic and electronic structure of the single crystal surface. Energy spectra contain information on the composition of the surface, while structural atomic information is obtained by direction measurements (photograms). In Ch.1 a description is given of the experimental equipment, in Ch.2 a characterization of the LEIS method. Ch.3 deals with the neutralization of keV-ions in surface scattering. Two different ways of data interpretation are presented. First a model is treated in which the observed directional dependence of neutralization action of the first atom layer of the surface is presented by a laterally varying thickness of the neutralizing layer. Secondly it is shown that the data can be reproduced by a more realistic, physical model based on atomic transition matrix elements. In Ch.4 the low energy hydrogen scattering is described. The study of the dissociation of H 2 + at an Ag surface r0230ted in a model based on electronic dissociation, initialized by electron capture into a repulsive (molecular) state. In Ch.5 finally the method is applied to the investigation of the surface structure of oxidized Fe. (Auth.)

  17. Organic adsorbates on metal surfaces. PTCDA and NTCDA on AG(110)

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Afshin

    2010-02-22

    , the inclusion of the major part of the attractive van-der-Waals interaction brings the adsorbate back to an arrangement close to parallel to the substrate, with very small differences in height between the different subunits. With respect to experimental data obtained on Ag(111), the calculated distance between adsorbate and substrate is somewhat smaller, indicating that the open Ag(110) surface interacts more strongly with the organic compounds. This is consistent with the fact that only Ag(110) induces a brickwall unit cell of the adsorbate, a clear sign for a particularly large adsorption energy. The resulting model geometries are analysed in terms of cohesive energy, Mulliken charges, core level shifts, and vibrational properties. (orig.)

  18. The Properties of Nano Silver (Ag-Geopolymer as Antibacterial Composite for Functional Surface Materials

    Directory of Open Access Journals (Sweden)

    Armayani. M

    2017-01-01

    Full Text Available The purpose of this research was to produce and characterize nano silver (Ag-geopolymer composite for functional surface materials. Geopolymer matrix was synthesized through alkali activation of metakaolin and nano silver was added into geopolymers paste with a mass of 0, 0.5 g, 1 g, 1.5 g and 2 g keeping the mass of metakaolin constant. The mixture was cured at 70°C/1 hour and stored for 7 days before conducting any measurements. The structure of the resulting composite was examined by using Rigaku Mini Flex II x-ray diffraction (XRD. Scanning Electron Microscopy (SEM coupled with Energy Dispersive Spectroscopy (EDS was used to examine the morphology of the composite surface as well as the capability of the composite to isolate the growth of bacteria. The thermal properties of composites in terms of their working temperature and enthalpy were examined by using Perkin Elmer Differential Scanning Calorimetry (DSC. The heat resistance of composite was observed through calcination at 750°C for 18 hours. The results indicate that the resulting composites were able resist up 750°C. SEM examinations showed that nano Ag-geopolymer composites were effectively restraining the growth of bacteria. It is suggested that nano Ag-geopolymer composites are suitable for functional surface applications such as floor and wall, kitchen ware utensils, hospital instruments, art and decoration materials.

  19. In situ structural study on underpotential deposition of Ag on Au(111) electrode using surface X-ray scattering technique

    OpenAIRE

    Kondo, Toshihiro; Morita, Jun; Okamura, Masayuki; Saito, Toshiya; Uosaki, Kohei

    2002-01-01

    In situ surface X-ray scattering (SXS) measurements were carried out to study the structure of a Ag layer on a Au(111) electrode formed by underpotential deposition (upd) in sulfuric acid solution. Specular rod profiles showed that a monolayer of Ag was formed at a potential between the second and third upd peaks, and a bilayer of Ag was formed at a potential between the third upd peak and bulk deposition. Non-specular rod profiles demonstrated that electrochemically deposited Ag atoms both i...

  20. Coexistence of hepatitis B surface antigen and antibody to hepatitis B surface may increase the risk of hepatocellular carcinoma in chronic hepatitis B virus infection: a retrospective cohort study.

    Science.gov (United States)

    Seo, Seung In; Choi, Hyeok Soo; Choi, Bo Youn; Kim, Hyoung Su; Kim, Hak Yang; Jang, Myoung Kuk

    2014-01-01

    The simultaneous detection of hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface (anti-HBs) is unusual in chronic hepatitis B virus (HBV) infection, but may be related with more advanced liver diseases. This retrospective long-term cohort study was aimed to investigate whether coexistence of HBsAg and anti-HBs may increase the risk of hepatocellular carcinoma (HCC) in chronic HBV infection. A total of 1,042 non-HCC patients were recruited and followed up for a median 4.3 years (range 1.0-22 years). Univariate and multivariate analyses were performed to identify the risk factors for HCC development. The prevalence of coexistence of HBsAg and anti-HBs was 7.0% (73/1,042). In univariate analysis, the 5-, 10-, and 15-year cumulative incidences of HCC were significantly higher in coexistence group than in HBsAg only group (12.7%, 23.4%, 69.4% vs. 4.9%, 13%, 20.6%, respectively; P = 0.008). In multivariate analysis, coexistence of HBsAg and anti-HBs [Hazard ratio (HR), 2.001; 95% confidence interval (CI), 1.023-3.912; P = 0.043] as well as male gender [HR, 1.898; 95% CI, 0.31-0.896; P = 0.018], age over 40 years [HR, 14.56; 95% CI, 4.499-47.08; P = 0.0001], and cirrhosis [HR, 7.995; 95% CI, 4.756-13.439; P = 0.0001] was identified as the independent factor for HCC development. Also, the cumulative incidence of HCC increased in proportion to the number of the risk factors. In conclusion, coexistence of HBsAg and anti-HBs may increase independently the risk of HCC development in chronic HBV infection. Therefore, consideration of HCC development is required in patients with coexistence of HBsAg and anti-HBs. © 2013 Wiley Periodicals, Inc.

  1. Theoretical calculations of the surface tension of Ag(1-x)-Cu(x) liquid alloys

    International Nuclear Information System (INIS)

    Aqra, Fathi; Ayyad, Ahmed

    2011-01-01

    Highlights: → A thermodynamic model for calculating the surface tension, and its temperature and composition dependences, of liquid binary alloys is described. → The model does not require the prior knowledge of the surface concentration and Gibbs energy. → The surface tension of the liquid Ag-Cu binary alloys has been calculated as a function of temperature and concentration. → The calculated values agree well with existing experimental data. - Abstract: The surface tension of silver-copper binary liquid alloys is calculated, in the frame work of Eyring theory. The calculations were made for different compositions (mole fraction, x Cu = 0, 0.2, 0.4, 0.6, 0.8 and 1), in the temperature range 1100-1800 K. The surface tension decreases with temperature increase, at a fixed copper fraction x Cu , and increases with increasing copper content. The calculated results are appropriately compared with existing literature data.

  2. Nucleation and growth of C60 overlayers on the Ag/Pt(111) dislocation network surface

    International Nuclear Information System (INIS)

    Ait-Mansour, K; Ruffieux, P; Xiao, W; Fasel, R; Groening, P; Groening, O

    2007-01-01

    We have investigated the room temperature growth of C 60 overlayers on the strainrelief dislocation network formed by two monolayers of Ag on Pt(111) by means of scanning tunneling microscopy. Extended domains of highly ordered dislocation networks with a typical superlattice parameter of 6.8 nm have been prepared, serving as templates for subsequent C 60 depositions. For low C 60 coverages, the molecules decorate the step-edges, where also the first islands nucleate. This indicates that at room temperature the C 60 molecules are sufficiently mobile to cross the dislocation lines and to diffuse to the step-edges. For C 60 coverages of 0.4 monolayer, besides the islands nucleated at the step-edges, C 60 islands also grow in the middle of terraces. The C 60 islands typically extend over several unit cells of the dislocation network and show an unusual orientation of the hexagonally close-packed C 60 lattice as compared to that found on the bare Ag(111) surface. Whereas C 60 grows preferentially in a (2 √3 x 2 √3) R30 0 structure on Ag(111), on the Ag/Pt(111) dislocation network the C 60 lattice adopts an orientation rotated by 30 0 , with the close-packed C 60 rows aligned along the dislocations which themselves are aligned along the Ag(1-10) directions. For higher coverages in the range of 1-2 monolayers, the growth of C 60 continues in a layer-by-layer fashion

  3. Ag Nanorod Arrays for SERS: Aspects of Spectral Reproducibility, Surface Contamination, and Spectral Sensitivity

    Directory of Open Access Journals (Sweden)

    Martin Šubr

    2015-01-01

    Full Text Available Ag nanorod arrays prepared by oblique angle vapor deposition (OAD represent regular, large area substrates for surface-enhanced Raman scattering (SERS spectroscopy. We studied uniformity and spectral reproducibility of silver OAD-fabricated substrates (AgOADs by spectral mapping of methylene blue. The results demonstrate good reproducibility apart from occasional “hot-spot” sites where the intensity is higher. The number of “hot-spots” represents 2%–6% of SERS-active sites of mapping substrate area. We were able to obtain good SERS spectra of testing amino acid tryptophan at 1 × 10−5 M concentration and three different free-base porphyrins down to ∼10−7 M concentration. We found out that keeping the AgOADs in a vacuum chamber overnight prevents the surface from binding any contaminants from the ambient atmosphere, without significant reduction in the SERS enhancement. Such substrates provide stable SERS enhancement even when stored for 1 year after preparation.

  4. Synthesis of surface plasmon resonance (SPR) triggered Ag/TiO2 photocatalyst for degradation of endocrine disturbing compounds

    International Nuclear Information System (INIS)

    Leong, Kah Hon; Gan, Bee Ling; Ibrahim, Shaliza; Saravanan, Pichiah

    2014-01-01

    Graphical abstract: - Highlights: • Ag/TiO 2 was synthesized with aid of natural photon stimulated photoreduction. • Deposited Ag prompted well the LSPRs, Schottky barrier for visible light utilization. • Photocatalytic activity was evaluated by degrading EDCs under visible light. • 3.0 wt% Ag/TiO 2 resulted with good photocatalytic efficiency over others. - Abstract: Surface deposition of silver nanoparticles (Ag NPs) onto the 100% anatase titania (Ag/TiO 2 ) for evolution of surface plasmon resonance (SPR) was achieved sustainably with the assistance of solar energy. The preparation resulted in Ag/TiO 2 photocatalyst with varied Ag depositions (0.5 wt%, 1.0 wt%, 3.0 wt% and 5.0 wt%). All obtained photocatalysts were characterized for the evolution of SPR via crystalline phase analysis, morphology, lattice fringes, surface area and pore size characteristics, chemical composition with chemical and electronic state, Raman scattering, optical and photoluminescence properties. The deposition of synthesized Ag NPs exhibited high uniformity and homogeneity and laid pathway for effective utilization of the visible region of electromagnetic spectrum through SPR. The depositions also lead for suppressing recombination rates of electron–hole. The photocatalytic evaluation was carried out by adopting two different class of endocrine disturbing compound (EDC) i.e., amoxicillin (pharmaceutical) and 2,4-dichlorophenol (pesticide) excited with artificial visible light source. Ag/TiO 2 with Ag > 0.5 wt% exhibited significant degradation efficiency for both amoxicillin and 2,4-dichlorophenol. Thus synthesized Ag/TiO 2 revealed the implication of plasmonics on TiO 2 for the enhanced visible light photocatalytic activity

  5. Synthesis of surface plasmon resonance (SPR) triggered Ag/TiO{sub 2} photocatalyst for degradation of endocrine disturbing compounds

    Energy Technology Data Exchange (ETDEWEB)

    Leong, Kah Hon; Gan, Bee Ling; Ibrahim, Shaliza [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Saravanan, Pichiah, E-mail: saravananpichiah@um.edu.my [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nanotechnology and Catalysis Research Center (NANOCAT), University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-11-15

    Graphical abstract: - Highlights: • Ag/TiO{sub 2} was synthesized with aid of natural photon stimulated photoreduction. • Deposited Ag prompted well the LSPRs, Schottky barrier for visible light utilization. • Photocatalytic activity was evaluated by degrading EDCs under visible light. • 3.0 wt% Ag/TiO{sub 2} resulted with good photocatalytic efficiency over others. - Abstract: Surface deposition of silver nanoparticles (Ag NPs) onto the 100% anatase titania (Ag/TiO{sub 2}) for evolution of surface plasmon resonance (SPR) was achieved sustainably with the assistance of solar energy. The preparation resulted in Ag/TiO{sub 2} photocatalyst with varied Ag depositions (0.5 wt%, 1.0 wt%, 3.0 wt% and 5.0 wt%). All obtained photocatalysts were characterized for the evolution of SPR via crystalline phase analysis, morphology, lattice fringes, surface area and pore size characteristics, chemical composition with chemical and electronic state, Raman scattering, optical and photoluminescence properties. The deposition of synthesized Ag NPs exhibited high uniformity and homogeneity and laid pathway for effective utilization of the visible region of electromagnetic spectrum through SPR. The depositions also lead for suppressing recombination rates of electron–hole. The photocatalytic evaluation was carried out by adopting two different class of endocrine disturbing compound (EDC) i.e., amoxicillin (pharmaceutical) and 2,4-dichlorophenol (pesticide) excited with artificial visible light source. Ag/TiO{sub 2} with Ag > 0.5 wt% exhibited significant degradation efficiency for both amoxicillin and 2,4-dichlorophenol. Thus synthesized Ag/TiO{sub 2} revealed the implication of plasmonics on TiO{sub 2} for the enhanced visible light photocatalytic activity.

  6. In situ Raman scattering study on a controllable plasmon-driven surface catalysis reaction on Ag nanoparticle arrays

    International Nuclear Information System (INIS)

    Dai, Z G; Xiao, X H; Zhang, Y P; Ren, F; Wu, W; Zhang, S F; Zhou, J; Jiang, C Z; Mei, F

    2012-01-01

    Control of the plasmon-driven chemical reaction for the transformation of 4-nitrobenzenethiol to p,p′-dimercaptoazobenzene by Ag nanoparticle arrays was studied. The Ag nanoparticle arrays were fabricated by means of nanosphere lithography. By changing the PS particle size, the localized surface plasmon resonance (LSPR) peaks of the Ag nanoparticle arrays can be tailored from 460 to 560 nm. The controlled reaction process was monitored by in situ surface-enhanced Raman scattering. The reaction can be dramatically influenced by varying the duration of laser exposure, Ag nanoparticle size, laser power and laser excitation wavelength. The maximum reaction speed was achieved when the LSPR wavelength of the Ag nanoparticle arrays matched the laser excitation wavelength. The experimental results reveal that the strong LSPR can effectively drive the transfer of the ‘hot’ electrons that decay from the plasmon to the reactants. The experimental results were confirmed by theoretical calculations. (paper)

  7. The role of surface defects in HOPG on the electrochemical and physical deposition of Ag

    Directory of Open Access Journals (Sweden)

    R. PETROVIC

    1999-08-01

    Full Text Available The role of defects on a substrate surface during the initial stages of nucleation and growth of Ag deposited electrochemically and physically on highly oriented pyrolytic graphite (HOPG has been observed ex situ by scanning tunneling microscopy (STM. The silver was electrodeposited under current controlled electrochemical conditions at 26 µA/cm2, which corresponded to a deposition rate of 0.1 monolayers (ML per second. For comparison, physical deposition of Ag on HOPG was performed by DC Ar+ ion sputtering, at the same deposition rate and for the same deposition times. In both cases, Ag grows in an island growth mode, but the distribution of the islands appears to be quite different. In physical deposition, the Ag islands are almost homogeneously distributed over the substrate surface and a slight accumulation of islands on steps does not contribute significantly to the overall morphology. This indicates the crucial role of point defects on the substrate in the initial stages of nucleation. In electrochemical deposition, more lined defects are observed after a flow of current, and their role in the beginning of the nucleation is more pronounced. Lined defects are responsible for the string-like shaped domains of deposited atoms. Also, the existence of string-like shaped nucleation exclusion zones is indicated. The problem of the formation of nucleation exclusion zones, which appear only in electrochemical deposition, has been reconsidered and a new explanaton of their formation is given. A mathematical model for the calculation of the radius of the nucleation exclusion zone has been developed.

  8. Probing surface plasmons in individual Ag nanoparticles in the ultra-violet spectral regime.

    Science.gov (United States)

    Chu, Ming-Wen; Sharma, Pradeep; Chang, Ching-Pin; Liou, Sz Chian; Tsai, Kun-Tong; Wang, Juen-Kai; Wang, Yuh-Lin; Chen, Cheng Hsuan

    2009-06-10

    Previous investigations of surface plasmons in Ag largely focused on their excitations in the visible spectral regime. Using scanning transmission electron microscopy with an electron beam of 0.2 nm in conjunction with electron energy-loss spectroscopy, we spectrally and spatially probe the surface plasmons in individual Ag nanoparticles (approximately 30 nm), grown on Si, in the ultra-violet spectral regime. The nanomaterials show respective sharp and broad surface-plasmon resonances at approximately 3.5 eV (approximately 355 nm) and approximately 7.0 eV (approximately 177 nm), and the correlated spectral calculations established their multipolar characteristics. The near-field distributions of the surface plasmons on the nanoparticles were also mapped out, revealing the predominant dipolar nature of the 3.5 eV excitation with obvious near-field enhancements at one end of the nano-object. The unveiled near-field enhancements have potential applications in plasmonics and molecular sensing.

  9. Probing surface plasmons in individual Ag nanoparticles in the ultra-violet spectral regime

    International Nuclear Information System (INIS)

    Chu, M-W; Chang, C-P; Liou, S C; Wang, J-K; Chen, C H; Sharma, Pradeep; Tsai, K-T; Wang, Y-L

    2009-01-01

    Previous investigations of surface plasmons in Ag largely focused on their excitations in the visible spectral regime. Using scanning transmission electron microscopy with an electron beam of 0.2 nm in conjunction with electron energy-loss spectroscopy, we spectrally and spatially probe the surface plasmons in individual Ag nanoparticles (∼30 nm), grown on Si, in the ultra-violet spectral regime. The nanomaterials show respective sharp and broad surface-plasmon resonances at ∼3.5 eV (∼355 nm) and ∼7.0 eV (∼177 nm), and the correlated spectral calculations established their multipolar characteristics. The near-field distributions of the surface plasmons on the nanoparticles were also mapped out, revealing the predominant dipolar nature of the 3.5 eV excitation with obvious near-field enhancements at one end of the nano-object. The unveiled near-field enhancements have potential applications in plasmonics and molecular sensing.

  10. Laser treatment of Ag@ZnO nanorods as long-life-span SERS surfaces.

    Science.gov (United States)

    Macias-Montero, Manuel; Peláez, Ramón J; Rico, Victor J; Saghi, Zineb; Midgley, Paul; Afonso, Carmen N; González-Elipe, Agustín R; Borras, Ana

    2015-02-04

    UV nanosecond laser pulses have been used to produce a unique surface nanostructuration of Ag@ZnO supported nanorods (NRs). The NRs were fabricated by plasma enhanced chemical vapor deposition (PECVD) at low temperature applying a silver layer as promoter. The irradiation of these structures with single nanosecond pulses of an ArF laser produces the melting and reshaping of the end of the NRs that aggregate in the form of bundles terminated by melted ZnO spherical particles. Well-defined silver nanoparticles (NPs), formed by phase separation at the surface of these melted ZnO particles, give rise to a broad plasmonic response consistent with their anisotropic shape. Surface enhanced Raman scattering (SERS) in the as-prepared Ag@ZnO NRs arrays was proved by using a Rhodamine 6G (Rh6G) chromophore as standard analyte. The surface modifications induced by laser treatment improve the stability of this system as SERS substrate while preserving its activity.

  11. Fabrication of bioactive, antibacterial TiO2 nanotube surfaces, coated with magnetron sputtered Ag nanostructures for dental applications.

    Science.gov (United States)

    Uhm, Soo-Hyuk; Lee, Sang-Bae; Song, Doo-Hoon; Kwon, Jae-Sung; Han, Jeon-Geon; Kim, Kyoung-Nam

    2014-10-01

    We investigated whether a silver coating on an anodic oxidized titania (TiO2) nanotube surface would be useful for preventing infections in dental implants. We used a magnetron sputtering process to deposit Ag nanoparticles onto a TiO2 surface. We studied different sputtering input power densities and maintained other parameters constant. We used scanning electron microscopy, X-ray diffraction, and contact angle measurements to characterize the coated surfaces. Staphylococcus aureus was used to evaluate antibacterial activity. The X-ray diffraction analysis showed peaks that corresponded to metallic Ag, Ti, O, and biocompatible anatase phase TiO2 on the examined surfaces. The contact angles of the Ag nanoparticle-loaded surfaces were significantly lower at 2.5 W/cm2 input power under pulsed direct current mode compared to commercial, untreated Ti surfaces. In vitro antibacterial analysis indicated that a significantly reduced number of S. aureus were detected on an Ag nanoparticle-loaded TiO2 nanotube surface compared to control untreated surfaces. No cytotoxicity was noted, except in the group treated with 5 W/cm2 input power density, which was the highest input of power density we tested for the magnetron sputtering process. Overall, we concluded that it was feasible to create antibacterial Ag nanoparticle-loaded titanium nanotube surfaces with magnetron sputtering.

  12. Surface enhanced Raman spectroscopic studies on magnetic Fe3O4@AuAg alloy core-shell nanoparticles

    Science.gov (United States)

    Sun, Hai-Long; Xu, Min-Min; Guo, Qing-Hua; Yuan, Ya-Xian; Shen, Li-Ming; Gu, Ren-Ao; Yao, Jian-Lin

    2013-10-01

    A facile approach has been developed to fabricate multifunctional Fe3O4@AuAg alloy core-shell nanoparticles, owning the magnetism of the core and the surface enhanced Raman spectroscopy (SERS) activities of the alloy shell. By changing the amount of HAuCl4 and AgNO3, Fe3O4@AuAg alloy nanoparticles with different component ratios of Au and Ag were successfully prepared. The surface plasmon resonance of the composition was linearly tuned in a wide range by varying the molar fraction of Ag and Au, suggesting the formation of AuAg alloy shell. SERS and magnetic enrichment effects were investigated by using thiophenol (TP) as the probe molecule. The SERS intensity was strongly dependent on the molar ratios of Au and Ag and the excitation line. Enrichment for the molecules with low concentration and on line SERS monitoring experiments were performed through combining the magnetism of the core and the SERS effect of the alloy shell. The results revealed that the magnetic enrichment efficiency was dramatically increased due to the strong magnetism of Fe3O4 core. In addition, the Fe3O4@AuAg nanoparticles were also used in the microfluidic chip to continuously detect different flowing solution in the channel. The detection time and amount of analyte were successfully decreased.

  13. Demographic and sociocultural characteristics of sickle anaemia children with positive hepatitis B surface antigenaemia in a tertiary health facility in Enugu.

    Science.gov (United States)

    Emechebe, G O; Emodi, I J; Ikefuna, A N; Ilechukwu, G C; Igwe, W C; Ejiofor, O S; Ilechukwu, C A

    2010-09-01

    Hepatitis B virus) infection is contracted through contact with body fluid of infected persons. Patients with sickle cell anaemia (SCA), a common haematological disorder in Nigeria, have tendencies to visit traditional healers who administer scarifications and ritual marks that may expose them to HBV infection. To determine the demographic and socio-cultural characteristics of children with SCA infected with HBV at the University of Nigeria Teaching Hospital Enugu. Two hundred and twenty one children aged 6 months to 17 years with SCA were recruited consecutively from October 2004 to April 2005. They were screened for HBsAg using ELISA method. There was no statistically difference in hepatitis B surface antigenaemia among different age group (P = 0.907). Social class did not significantly influence the prevalence of HBsAg among subjects (p = 0.887). Socio-cultural practices like circumcision and scarification did not influence the prevalence of HBsAg, (p = 0.636) (p = 0.771) respectively. Significantly higher number of people from lowest socioeconomic class practice scarification (p = 0.0001). Demographic and sociocultural factors do not appear to influence the prevalence of HBsAg among children with SCA in Enugu, Nigeria.

  14. Characterization of surface Ag nanoparticles in nanocomposite a-C:Ag coatings by grazing incidence X-ray diffraction at sub-critical angles of incidence

    Energy Technology Data Exchange (ETDEWEB)

    Manninen, N.K.; Oliveira, J.C.; Cavaleiro, A. [University of Coimbra, SEG-CEMUC, Mechanical Engineering Department, Coimbra (Portugal); Carvalho, S. [University of Minho, GRF-CFUM, Physics Department, Guimaraes (Portugal)

    2016-03-15

    Silver diffusion within nanocomposite films and/or toward the film surface is often observed during annealing of the silver-based nanocomposite films. In order to control and/or minimize this process, it is crucial to characterize the aggregated silver nanoparticles on the films surface. In this paper grazing incidence X-ray diffraction (GIXRD) with both sub-critical and supra-critical angles of incidence is used to characterize the Ag nanoparticles distribution, shape and structure both inside the matrix and on the nanocomposite film surface. The nanocomposite carbon coating containing Ag nanoparticles (a-C:Ag) was deposited by dc magnetron sputtering. The coatings were analyzed by GIXRD using fixed incident angles both below and above the critical angle for total reflection. By using sub-critical angles it was possible to eliminate diffraction from the bulk material allowing to estimate the size distribution of the nanoparticles sitting on the surface. The results obtained by GIXRD analysis were checked through comparison with the observations made by both TEM and SEM analysis. The proposed methodology can be used to characterized nanoparticles deposition on a surface and/or island formation during film growth as long an adequate substrate with high critical angle for total reflection is used. (orig.)

  15. On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

    Science.gov (United States)

    Mikhlin, Yuri L.; Vorobyev, Sergey A.; Saikova, Svetlana V.; Vishnyakova, Elena A.; Romanchenko, Alexander S.; Zharkov, Sergey M.; Larichev, Yurii V.

    2018-01-01

    Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

  16. Growth of Ag, Au, Cu, and Pt nanostructures on surfaces by micropatterned laser-image formations

    Science.gov (United States)

    Pacheco-Londono, Leonardo C.; Aparicio-Bolaño, Joaquín.; Primera-Pedrozo, Oliva M.; Hernandez-Rivera, Samuel P.

    2011-07-01

    Silver, gold, copper and platinum nanoparticles (NPs) were grown on surfaces in the form of patterns by the exposure of laser radiation onto droplets of metal ion solutions and the aid of a reducing agent. The generation of patterns from metallic NPs was achieved by combining induced growth of NPs and nanostructures by laser incidence directly on surfaces and optical image formation techniques for transferring the patterns. Near-UV (363.8nm) and visible (532nm) laser wavelengths were used for the laser-induced growth of NPs into microstructures on glass, quartz, stainless steel, silicon, and gold-on-silicon substrates. The sizes of the patterns formed were on the micrometer scale and the sizes of the transferred patterns were on the millimeter scale. The patterns formed were generated by optical transference of image and interference of laser beams. Ag and Au substrates were highly active in surface enhanced Raman spectroscopy (SERS). The enhanced Raman activity was measured for SERS probe molecules: 9H-purin-6-amine (adenine) and 1,2-bis (4-pyridyl)-ethane analytes on Ag and Au substrates, respectively. The enhancement factors obtained were 1.8×105 and 6.2×106, respectively.

  17. Rough surface Au@Ag core-shell nanoparticles to fabricating high sensitivity SERS immunochromatographic sensors.

    Science.gov (United States)

    Fu, Qiangqiang; Liu, Hongwu Liu; Wu, Ze; Liu, An; Yao, Cuize; Li, Xiuqing; Xiao, Wei; Yu, Shiting; Luo, Zhi; Tang, Yong

    2015-11-14

    Immunochromatographic sensors (ICSs) are inexpensive, simple, portable, and robust, thus making ICSs commonplace in clinical diagnoses, food testing, and environmental monitoring. However, commonly used gold nanoparticles (AuNPs) ICSs have low sensitivity. Therefore, we developed highly sensitive surface enhanced Raman scattering (SERS) ICSs. To enhance the sensitivity of SERS ICSs, rough surface core-shell Au@Ag nanoparticles (RSAu@AgNPs) were prepared by coating silver on the surface of gold nanoflowers (AuNFs). Then these nanoparticles were used as SERS substrate in the SERS ICSs, after which the SERS ICSs were implemented to detect haemoglobin and heavy metal cadmium ion (Cd(2+)). The limit of detection (LOD) of the SERS ICSs for detecting haemoglobin was 8 ng/mL, and the linear range of the SERS ICSs was from 31.3 to 2000 ng/mL. The LOD of the SERS ICSs for detecting Cd(2+) was 0.05 ng/mL and the linear analysis range was from 0.05 to 25 ng/mL. The cross reactivity of the SERS ICSs was studied and results showed that the SERS ICSs exhibited highly specific for detection of haemoglobin and Cd(2+), respectively. The SERS ICSs were then used to detect haemoglobin (spiked in serum and in stool) and Cd(2+) (spiked in tap water, river water, and soil leaching water), and the results showed high recovery. These characteristics indicated that SERS ICSs were ideal tools for clinical diagnosis and environmental pollution monitoring.

  18. Morphology and grain structure evolution during epitaxial growth of Ag films on native-oxide-covered Si surface

    International Nuclear Information System (INIS)

    Hur, Tae-Bong; Kim, Hong Koo; Perello, David; Yun, Minhee; Kulovits, Andreas; Wiezorek, Joerg

    2008-01-01

    Epitaxial nanocrystalline Ag films were grown on initially native-oxide-covered Si(001) substrates using radio-frequency magnetron sputtering. Mechanisms of grain growth and morphology evolution were investigated. An epitaxially oriented Ag layer (∼5 nm thick) formed on the oxide-desorbed Si surface during the initial growth phase. After a period of growth instability, characterized as kinetic roughening, grain growth stagnation, and increase of step-edge density, a layer of nanocrystalline Ag grains with a uniform size distribution appeared on the quasi-two-dimensional layer. This hierarchical process of film formation is attributed to the dynamic interplay between incoming energetic Ag particles and native oxide. The cyclic interaction (desorption and migration) of the oxide with the growing Ag film is found to play a crucial role in the characteristic evolution of grain growth and morphology change involving an interval of grain growth stagnation

  19. Fabrication of Ag/ZnO heterostructure and the role of surface coverage of ZnO microrods by Ag nanoparticles on the photophysical and photocatalytic properties of the metal-semiconductor system

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Bikash; Sarma, Bimal K., E-mail: sarmabimal@gmail.com

    2017-07-15

    Highlights: • Fabrication of Ag/ZnO heterostructure by facile chemical processes. • Decoration of plasmonic Ag nanoparticles on ZnO microrods through direct attachment. • Quenching of photoluminescence is observed in Ag/ZnO heterostructure. • Extent of surface coverage governs photophysical and photochemical properties. - Abstract: This report presents findings on microstructural, photophysical, and photocatalytic properties of Ag/ZnO heterostructure grown on flexible and silicon substrates. ZnO microrods are prepared by thermal decomposition method for different solute concentrations and Ag/ZnO heterostructure are fabricated by photo-deposition of Ag nanoparticles on ZnO microrods. X-ray diffraction and electron microscopy studies confirm that ZnO microrods belong to the hexagonal wurtzite structure and grown along [001] direction with random alignment showing that majority microrods are aligned with (100) face parallel to the sample surface. Plasmonic Ag nanoparticles are attached to different faces of ZnO. In the optical reflection spectra of Ag/ZnO heterostructure, the surface plasmon resonance peak due to Ag nanoparticles appears at 445 nm. Due to the oxygen vacancies the band gaps of ZnO microrods turn out to be narrower compared to that of bulk ZnO. The presence of Ag nanoparticles decreases the photoluminescence intensity which might be attributed to the non-radiative energy and direct electron transfer in the plasmon–exciton system. The quenching of photoluminescence in Ag/ZnO heterostructure at different growth conditions depend on the extent of surface coverage of ZnO by plasmonic Ag nanoparticles. Photocatalytic degradation efficiency of Ag/ZnO heterostructure is higher than that of ZnO microrods. The extent of surface coverage of ZnO microrods by Ag nanoparticles is crucial for the observed changes in photophysical and photochemical properties.

  20. Helicobacter pylori, hepatitis viruses A, C, E antibodies and HBsAg-prevalence and associated risk factors in pediatric communities of karachi

    International Nuclear Information System (INIS)

    Aziz, S.; Muzzafar, R.; Hafiz, S.; Abbas, Z.; Zafar, M.N.; Naqvi, S.A.A.; Rizvi, S.A.U.H.

    2007-01-01

    To document the prevalence of Helicobacter pylori (H. pylori), Hepatitis A virus (HAV), Hepatitis C virus (HCV), Hepatitis E virus (HEV) antibodies and Hepatitis B virus surface antigen (HBsAg), in the pediatric age group of low socioeconomic urban communities of Karachi and to identify risk factors associated with these infections. Three hundred and eighty children, ages 5 months to 15 years were investigated. Venous blood samples were collected and questionnaire filled on sociodemographic characteristics (family income, number of dependents in the family, area of living, number of people per room per house, and number of children sharing bed with parents and siblings). Gastrointestinal symptoms were recorded. Anti-HAV IgG (Hepatitis A virus IgG antibody), anti-HCV (Hepatitis C virus antibody), anti-HEV (Hepatitis E antibodies) and HBsAg, were analyzed by enzyme immunoassays (EIAs). Samples were also screened for anti-HIV1/2 (human immunodeficiency virus 1 and 2 antibodies by EIA. IgG antibodies against H. pylori were detected by immunochromatography. A correlation between increasing age and seroconversion was seen for hepatotropic viruses. At 14 years and above,100% of the children were found to be positive for anti-HAV, 26% for anti-HEV, and 1.4%, for anti-HCV while HBsAg was positive in 1.9%. H. pylori infection did not show a significant increase with age. Both anti-HAV and anti-H. pylori were present simultaneously in 30% of the population investigated. With age, increasing number of children acquired antibodies against hepatotropic viruses and H. pylori. Occurrence of HBsAg and anti-HEV at a later age suggests horizontal, rather than vertical transmission. (author)

  1. Adsorption of squaraine molecules to Au(111) and Ag(001) surfaces

    Science.gov (United States)

    Luft, Maike; Groß, Boris; Schulz, Matthias; Lützen, Arne; Schiek, Manuela; Nilius, Niklas

    2018-02-01

    The adsorption of anilino squaraines, an important chromophore for the use in organic solar cells, to Ag(001) and Au(111) has been studied with scanning tunneling microscopy. Self-assembly into square building blocks with eight molecules per unit cell is revealed on the Ag surface, while no ordering effects occur on gold. The squaraine-silver interaction is mediated by the carbonyl and hydroxyl oxygens located in the center of the molecule. The intermolecular coupling, on the other hand, is governed by hydrogen bonds formed between the terminal isobutyl groups and oxygen species of adjacent molecules. The latter gets maximized by rotating the molecules by a few degrees against a perfect square alignment. A similar molecular pattern does not form on Au(111) due to symmetry mismatch. Moreover, the high electronegativity of gold reduces the directing effect of oxygen-metal bonds that trigger the ordering process on silver. As a consequence, only frustrated three-fold symmetric units that do not expand into an ordered molecular network are present on the gold surface.

  2. Surface topographical and structural analysis of Ag{sup +}-implanted polymethylmethacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Arif, Shafaq, E-mail: sarif2005@gmail.com [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Rafique, M. Shahid [Department of Physics, University of Engineering & Technology, Lahore 54000 (Pakistan); Saleemi, Farhat [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Naab, Fabian; Toader, Ovidiu [Department of Nuclear Engineering and Radiological Sciences, Michigan Ion Beam Laboratory, University of Michigan, MI 48109-2104 (United States); Sagheer, Riffat [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Bashir, Shazia [Center for Advanced Studies in Physics (CASP), Government College University, Lahore 54000 (Pakistan); Zia, Rehana [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Siraj, Khurram; Iqbal, Saman [Department of Physics, University of Engineering & Technology, Lahore 54000 (Pakistan)

    2016-08-15

    Specimens of polymethylmethacrylate (PMMA) were implanted with 400-keV Ag{sup +} ions at different ion fluences ranging from 1 × 10{sup 14} to 5 × 10{sup 15} ions/cm{sup 2} using a 400-kV NEC ion implanter. The surface topographical features of the implanted PMMA were investigated by a confocal microscope. Modifications in the structural properties of the implanted specimens were analyzed in comparison with pristine PMMA by X-ray diffraction (XRD) and Raman spectroscopy. UV–Visible spectroscopy was applied to determine the effects of ion implantation on optical transmittance of the implanted PMMA. The confocal microscopic images revealed the formation of hillock-like microstructures along the ion track on the implanted PMMA surface. The increase in ion fluence led to more nucleation of hillocks. The XRD pattern confirmed the amorphous nature of pristine and implanted PMMA, while the Raman studies justified the transformation of Ag{sup +}-implanted PMMA into amorphous carbon at the ion fluence of ⩾5 × 10{sup 14} ions/cm{sup 2}. Moreover, the decrease in optical transmittance of PMMA is associated with the formation of hillocks and ion-induced structural modifications after implantation.

  3. Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

    Science.gov (United States)

    Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2015-11-01

    The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

  4. Synthesis of Ag2O nanocrystals with systematic shape evolution from cubic to hexapod structures and their surface properties.

    Science.gov (United States)

    Lyu, Lian-Ming; Wang, Wei-Ching; Huang, Michael H

    2010-12-17

    We report the development of a facile method for the synthesis of Ag(2)O crystals with systematic shape evolution from cubic to edge- and corner-truncated cubic, rhombicuboctahedral, edge- and corner-truncated octahedral, octahedral, and hexapod structures by mixing AgNO(3), NH(4)NO(3), and NaOH at molar ratios of 1:2:11.8. A sufficient volume of NaOH solution was first added to a mixture of AgNO(3) and NH(4)NO(3) solution to promote the formation of Ag(NH(3))(2)(+) complex ions and the growth of Ag(2)O nanocrystals with good morphological control. The crystals are mostly submicrometer-sized. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterization has been performed to determine the crystalline surface facets. A band gap value of approximately 1.45 eV has been found for the octahedral Ag(2)O crystals. By changing the molar ratios of AgNO(3)/NH(4)NO(3)/NaOH to 1:2:41.8, corner-depressed rhombicuboctahedra and elongated hexapods were obtained as a result of enhanced crystal growth along the [100] directions. Smaller nanocubes with average sizes of approximately 200 and 300 nm and octapods can also be prepared by adjusting the reagent molar ratios and their added volumes. Both the octahedra and hexapods with largely silver atom-terminated {111} surface facets responded repulsively and moved to the surface of the solution when dispersing in a solution of positively charged methylene blue, but can be suspended in a negatively charged methyl orange solution. The cubes and octapods, bounded by the {100} faces, were insensitive to the molecular charges in solution. The dramatic facet-dependent surface properties of Ag(2)O crystals have been demonstrated.

  5. Reduced prevalence of hepatitis B surface antigen positivity among pregnant women born after the national implementation of immunoprophylaxis for babies born to hepatitis B virus-carrier mothers in Japan.

    Science.gov (United States)

    Sugiyama, Aya; Ohisa, Masayuki; Nagashima, Shintaro; Yamamoto, Chikako; Chuon, Channarena; Fujii, Toshiko; Akita, Tomoyuki; Katayama, Keiko; Kudo, Yoshiki; Tanaka, Junko

    2017-11-01

    We aimed to estimate hepatitis B surface antigen (HBsAg) positivity among birth year-stratified pregnant women in Hiroshima, Japan, and compare prevalence rates between women born before and after implementation of a national immunoprophylactic vaccination program for babies born to hepatitis B virus (HBV) carrier mothers in Japan. Pregnant women who gave birth at all delivery hospitals/clinics in Hiroshima prefecture between 1 April 2010 and 31 March 2011 were eligible. Lists collected from each institution included survey items such as age (pregnant woman's birth year) and HBsAg and hepatitis C virus (HCV) antibody (anti-HCV) test results, which were posted anonymously and non-consolidated from medical records. We calculated the HBsAg and anti-HCV prevalence in our cohort according to the mothers' birth year. In 41 of 58 hospitals/clinics, 15 233 and 15 035 pregnant women underwent HBsAg and anti-HCV testing, corresponding to 59.6% and 58.9% of 25 546 births in the 2010 fiscal year, respectively. The overall HBsAg positive rate was 0.51% (95% confidence interval [CI], 0.40-0.63%), and an extremely low prevalence (0.10%; 95% CI, 0.00-0.25%) was observed among pregnant women born after 1986. However, the prevalence in this study was slightly higher than the nationwide value (0.31%) and the Chugoku region-specific value (0.46%) among first-time blood donors at Japanese Red Cross blood centers between 2001 and 2006. No significant difference in anti-HCV positivity was observed. Only two pregnant women born after the preventive program implementation were HBsAg-positive. Perinatal HBV transmission is estimated to be almost completely inhibited in the next generation. © 2017 The Authors. Hepatology Research published by John Wiley & Sons Australia, Ltd on behalf of Japan Society of Hepatology.

  6. Tuning the surface potential of Ag surfaces by chemisorption of oppositely-oriented thiolated carborane dipoles

    Czech Academy of Sciences Publication Activity Database

    Lübben, J.F.; Baše, Tomáš; Rupper, P.; Künniger, T.; Macháček, Jan; Guimond, S.

    2011-01-01

    Roč. 354, č. 1 (2011), s. 168-174 ISSN 0021-9797 R&D Projects: GA AV ČR(CZ) IAA400320901 Keywords : Adsorption * Thiolated carboranes * Silver surface * Surface potential * X-ray photoelectron spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 3.070, year: 2011

  7. In situ controllable synthesis of novel surface plasmon resonance-enhanced Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} composite for enhanced and stable visible light photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Jiali [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Dai, Kai, E-mail: daikai940@chnu.edu.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Zhang, Jinfeng [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Lu, Luhua, E-mail: lhlu@cug.edu.cn [Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Liang, Changhao, E-mail: chliang@issp.ac.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 23003 (China); Geng, Lei; Wang, Zhongliao; Yuan, Guangyu; Zhu, Guangping [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China)

    2017-01-01

    Highlights: • Novel Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} ternary photocatalyst was prepared. • Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} showed enhanced catalytic activity. • Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} showed long reusable life. - Abstract: A novel hierarchical Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} ternary visible-light-driven photocatalyst was successfully synthesized by in situ doping Ag{sub 2}WO{sub 4} with Bi{sub 2}MoO{sub 6} nanosheets through a facile hydrothermal and photochemical process. The morphology, structure, optical performance and crystallinity of the products were measured by field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), UV–vis diffuse reflectance spectroscopy (DRS) and X-ray diffraction (XRD). The results showed that Ag{sub 2}WO{sub 4}/Ag was uniformly dispersed on the surface of Bi{sub 2}MoO{sub 6} nanosheets. The photocatalytic performance of Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} heterostructures was evaluated by the degradation of methylene blue (MB) under 410 nm LED arrays. The ternary Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} nanocomposite exhibits higher photocatalytic activity than Bi{sub 2}MoO{sub 6} and Ag{sub 2}WO{sub 4}. The synergistic effect of Ag{sub 2}WO{sub 4} and Bi{sub 2}MoO{sub 6} could generated more heterojunctions which promoted photoelectrons transfer from Ag{sub 2}WO{sub 4} to Bi{sub 2}MoO{sub 6}, leading to the improvement of photocatalytic performance by photoelectrons-holes recombination suppression. At the same time, the surface plasmon resonance of Ag{sub 2}WO{sub 4}/Ag/Bi{sub 2}MoO{sub 6} is another crucial reason for the high photocatalytic performance of organic pollutants degradation. And the 20 wt% Ag{sub 2}WO{sub 4}-loaded Bi{sub 2}MoO{sub 6} shows the optimal photocatalytic performance in the degradation of MB. In addition, the ternary composites can be easily reclaimed by precipitation and exhibits high stability of photocatalytic

  8. The value of serum Hepatitis B surface antigen quantification in ...

    African Journals Online (AJOL)

    HBe status, HBV DNA concentrations and serum ALT levels, based on the European Association for the study of the liver (EASL) guidelines.Serum HBsAg titres were measured using the Elecsys HBsAg II Quant assay (Roche Diagnostics).

  9. Cultural Influences on Hepatitis B Surface Antigen Seropositivity in ...

    African Journals Online (AJOL)

    Objective: To determine the role of cultural influences, namely: circumcision, ear piercing and traditional scarification, on HbsAg seropositivity among primary school children in Nnewi. Subjects and Method: Two hundred and thirty seven randomly selected primary school children aged 5-12 years, were screened for HbsAg.

  10. Preparation of dendritic Ag/Au bimetallic nanostructures and their application in surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Yi Zao; Chen Shanjun; Chen Yan; Luo Jiangshan; Wu Weidong; Yi Yougen; Tang Yongjian

    2012-01-01

    Dendritic Ag/Au bimetallic nanostructures have been synthesized via a multi-stage galvanic replacement reaction of Ag dendrites in a chlorauric acid (HAuCl 4 ) solution at room temperature. After five stages of replacement reaction, one obtains structures with protruding nanocubes; these will mature into many porous structures with a few Ag atoms that are left over dendrites. The morphological and compositional changes which evolved with reaction stages were analyzed by using scanning electron microscopy, transmission electron microscopy, UV–visible spectroscopy, selected area electron diffraction and energy-dispersive X-ray spectrometry. The replacement of Ag with Au was confirmed. A formation mechanism involving the original development of Ag dendrites into porous structures with the growth of Au nanocubes on this underlying structure as the number of reaction stages is proposed. This was confirmed by surface-enhanced Raman scattering (SERS). The dendritic Ag/Au bimetallic nanostructures could be used as efficient SERS active substrates. It was found that the SERS enhancement ability was dependent on the stage of galvanic replacement reaction. - Highlights: ► Dendritic Ag/Au bimetallic nanostructures have been synthesized. ► Protruding cubic nanostructures obtained after 5 stages mature into porous structures. ► SERS results allow confirm the proposed formation mechanism. ► The nanostructures could be used as efficient SERS active substrates.

  11. Ag Nanorods-Oxide Hybrid Array Substrates: Synthesis, Characterization, and Applications in Surface-Enhanced Raman Scattering

    Directory of Open Access Journals (Sweden)

    Lingwei Ma

    2017-08-01

    Full Text Available Over the last few decades, benefitting from the sufficient sensitivity, high specificity, nondestructive, and rapid detection capability of the surface-enhanced Raman scattering (SERS technique, numerous nanostructures have been elaborately designed and successfully synthesized as high-performance SERS substrates, which have been extensively exploited for the identification of chemical and biological analytes. Among these, Ag nanorods coated with thin metal oxide layers (AgNRs-oxide hybrid array substrates featuring many outstanding advantages have been proposed as fascinating SERS substrates, and are of particular research interest. The present review provides a systematic overview towards the representative achievements of AgNRs-oxide hybrid array substrates for SERS applications from diverse perspectives, so as to promote the realization of real-world SERS sensors. First, various fabrication approaches of AgNRs-oxide nanostructures are introduced, which are followed by a discussion on the novel merits of AgNRs-oxide arrays, such as superior SERS sensitivity and reproducibility, high thermal stability, long-term activity in air, corrosion resistivity, and intense chemisorption of target molecules. Next, we present recent advances of AgNRs-oxide substrates in terms of practical applications. Intriguingly, the recyclability, qualitative and quantitative analyses, as well as vapor-phase molecule sensing have been achieved on these nanocomposites. We further discuss the major challenges and prospects of AgNRs-oxide substrates for future SERS developments, aiming to expand the versatility of SERS technique.

  12. Adsorption of Ni, Pd, Pt, Cu, Ag and Au on the Fe3O4(111) surface

    Science.gov (United States)

    Yu, Xiaohu; Tian, Xinxin; Wang, Shengguang

    2014-10-01

    The interaction of Group 10 and 11 transition metals with the magnetite (111) surface has been investigated using the GGA + U density functional theory and periodic slab surface models. It was found that these transition metals adsorb stronger on an oxygen-terminated magnetite (111) surface than on an iron-terminated surface. On an oxygen-terminated surface, the adsorption strength is in the order of Ni > Pt Cu > Pd > Ag Au. In contrast, the order on an iron-terminated surface is Ni > Pt Cu > Au > Pd Ag. The adsorption strength was found to correlate well with the average lengths of metal-oxygen bonds. The magnetite (111) surfaces largely modify the electronic structures of the transition metals. Compared to their density of states in bulk structures, the atomically adsorbed transition metals have narrower d bands, and their d-band centers are closer to the Fermi levels. This implies the higher activities of the atomically adsorbed transition metals.

  13. Understanding early serum hepatitis D virus and hepatitis B surface antigen kinetics during pegylated interferon-alpha therapy via mathematical modeling.

    Science.gov (United States)

    Guedj, Jeremie; Rotman, Yaron; Cotler, Scott J; Koh, Christopher; Schmid, Peter; Albrecht, Jeff; Haynes-Williams, Vanessa; Liang, T Jake; Hoofnagle, Jay H; Heller, Theo; Dahari, Harel

    2014-12-01

    There is little information on the early kinetics of hepatitis delta virus (HDV) and hepatitis B surface antigen (HBsAg) during interferon-α therapy. Here a mathematical model was developed and fitted to frequent HDV and HBsAg kinetic data from 10 patients during the first 28 weeks of pegylated-interferon-α2a (peg-IFN) therapy. Three patients achieved a complete virological response (CVR), defined as undetectable HDV 6 months after treatment stopped with loss of HBsAg and anti-HBsAg seroconversion. After initiation of therapy, a median delay of 9 days (interquartile range [IQR]: 5-15) was observed with no significant changes in HDV level. Thereafter, HDV declined in a biphasic manner, where a rapid first phase lasting for 25 days (IQR: 23-58) was followed by a slower or plateau second phase. The model predicts that the main effect of peg-IFN is to reduce HDV production/release with a median effectiveness of 96% (IQR: 93-99.8). Median serum HDV half-life (t1/2 ) was estimated as 2.9 days (IQR: 1.5-5.3) corresponding to a pretreatment production and clearance of about 10(10) (IQR: 10(9.7) -10(10.7) ) virions/day. None of the patients with flat second phase in HDV achieved CVR. HBsAg kinetics of decline paralleled the second phase of HDV decline consistent with HBsAg-productive-infected cells being the main source of production of HDV, with a median t1/2 of 135 days (IQR: 20-460). The interferon lambda-3 polymorphism (rs12979860) was not associated with kinetic parameters. Modeling results provide insights into HDV-host dynamics, the relationship between serum HBsAg levels and HBsAg-infected cells, IFN's mode of action, and its effectiveness. The observation that a flat second phase in HDV and HBsAg kinetics was associated with failure to achieve CVR provides the basis to develop early stopping rules during peg-IFN treatment in HDV-infected patients. © 2014 by the American Association for the Study of Liver Diseases. This article has been contributed to by U

  14. Adsorption behavior of Fe atoms on a naphthalocyanine monolayer on Ag(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Linghao; Wu, Rongting; Bao, Deliang; Ren, Junhai; Zhang, Yanfang; Zhang, Haigang; Huang, Li; Wang, Yeliang; Du, Shixuan; Huan, Qing; Gao, Hong-Jun

    2015-05-29

    Adsorption behavior of Fe atoms on a metal-free naphthalocyanine (H2Nc) monolayer on Ag(111) surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional theory (DFT) based calculations. We found that the Fe atoms adsorbed at the centers of H2Nc molecules and formed Fe-H2Nc complexes at low coverage. DFT calculations show that the configuration of Fe at the center of a molecule is the most stable site, in good agreement with the experimental observations. After an Fe-H2Nc complex monolayer was formed, the extra Fe atoms self-assembled to Fe clusters of uniform size and adsorbed dispersively at the interstitial positions of Fe-H2Nc complex monolayer. Furthermore, the H2Nc monolayer grown on Ag(111) could be a good template to grow dispersed magnetic metal atoms and clusters at room temperature for further investigation of their magnetism-related properties.

  15. HNO₃-assisted polyol synthesis of ultralarge single-crystalline Ag microplates and their far propagation length of surface plasmon polariton.

    Science.gov (United States)

    Chang, Cheng-Wei; Lin, Fan-Cheng; Chiu, Chun-Ya; Su, Chung-Yi; Huang, Jer-Shing; Perng, Tsong-Pyng; Yen, Ta-Jen

    2014-07-23

    We developed a HNO3-assisted polyol reduction method to synthesize ultralarge single-crystalline Ag microplates routinely. The edge length of the synthesized Ag microplates reaches 50 μm, and their top facets are (111). The mechanism for dramatically enlarging single-crystalline Ag structure stems from a series of competitive anisotropic growths, primarily governed by carefully tuning the adsorption of Ag(0) by ethylene glycol and the desorption of Ag(0) by a cyanide ion on Ag(100). Finally, we measured the propagation length of surface plasmon polaritons along the air/Ag interface under 534 nm laser excitation. Our single-crystalline Ag microplate exhibited a propagation length (11.22 μm) considerably greater than that of the conventional E-gun deposited Ag thin film (5.27 μm).

  16. Thermal switching of the electrical conductivity of Si(111)(√3x√3)Ag due to a surface phase transition

    International Nuclear Information System (INIS)

    Wells, J W; Kallehauge, J F; Hofmann, Ph

    2007-01-01

    The temperature-dependent surface conductivity of the Si(111)(√3x√3)Ag surface was measured using a microscopic four-point probe. The conductivity was found to undergo a sharp increase of about three orders of magnitude when the system was heated above about 220 K. This strong conductivity change is reversible and attributed to the phase transition which is generally believed to occur on this surface. It is also shown that, in order to find the true surface conductivity, it is necessary to separate it from the contribution of the bulk and space charge layer. In this work, this is achieved by using a finite-element model. A percolating network of Ag islands on Si(111) was also studied and a much simpler behaviour (compared to that of Si(111))(√3x√3)Ag) was found. The temperature-dependent conductivity of this system was found to display typical metallic behaviour. The absolute value of the conductivity is comparable to the value expected by modelling the Ag film as exhibiting the bulk Ag transport properties

  17. Protective effect of hepatitis B vaccine combined with two-dose hepatitis B immunoglobulin on infants born to HBsAg-positive mothers.

    Directory of Open Access Journals (Sweden)

    Huaibin Zou

    Full Text Available Despite the use of hepatitis B (HB vaccine and hepatitis B immunoglobulin (HBIG, a portion of infants are still non- or low-responders, or even immunoprophylaxis failure. We aimed to determine the immune response in the infants from the mothers being positive for hepatitis B surface antigen (HBsAg, by which the infants received three doses of HB vaccine in combination with two-dose 200 IU HBIG injections.In this retrospective study, 621 infants from HBsAg-positive mothers in Beijing YouAn Hospital between January 2008 and December 2009 were included. All the infants were given three doses of 10 µg HB vaccine (at 0, 1 and 6 months of age and two-dose of 200 IU HBIG (at birth and in 2 weeks of age. Serum HBsAg and antibody to HBsAg (anti-HBs in all the infants were determined at 7 months of age.Of the 621 infants, 2.9% were immunoprophylaxis failure (positive for HBsAg, 1.4% were non-responders (anti-HBs undetectable, 95.7% were responders. The 594 responders could be categorized into three subsets, 22 were 10 to 99 IU/L for anti-HBs levels, 191 were 100 to 999 IU/L, and 381 were ≥1000 IU/L. The immunoprophylaxis failure rate was at 0% and 5.2% for the infants of HBeAg-negative and HBeAg-positive mothers(P<0.001. Infants from mothers with detectable HBV DNA had higher incidence of immunoprophylaxis failure than those of mothers without detectable HBV DNA (P = 0.002. The factors including gender, birth weight, gestation weeks, the rates of maternal HBeAg-positive, and detectable HBV DNA did not contribute to the no response to HB vaccination.Through vaccination by three doses of HB and two-dose of HBIG, majority of the infants (95.7% achieved a protective level of anti-HBs at 7 months of age. Maternal HBeAg-positive and HBV DNA detectable were associated with the immunoprophylaxis failure, but not contribute to the non- or low-response to HB vaccination.

  18. Lateral and vertical manipulations of single atoms on the Ag(1 1 1) surface with the copper single-atom and trimer-apex tips

    International Nuclear Information System (INIS)

    Xie Yiqun; Yang Tianxing; Ye Xiang; Huang Lei

    2011-01-01

    We study the lateral and vertical manipulations of single Ag and Cu atoms on the Ag(1 1 1) surface with the Cu single-atom and trimer-apex tips using molecular statics simulations. The reliability of the lateral manipulation with the Cu single-atom tip is investigated, and compared with that for the Ag tips. We find that overall the manipulation reliability (MR) increases with the decreasing tip height, and in a wide tip-height range the MR is better than those for both the Ag single-atom and trimer-apex tips. This is due to the stronger attractive force of the Cu tip and its better stability against the interactions with the Ag surface. With the Cu trimer-apex tip, the single Ag and Cu adatoms can be picked up from the flat Ag(1 1 1) surface, and moreover a reversible vertical manipulation of single Ag atoms on the stepped Ag(1 1 1) surface is possible, suggesting a method to modify two-dimensional Ag nanostructures on the Ag(1 1 1) surface with the Cu trimer-apex tip.

  19. Surface sensing behavior and band edge properties of AgAlS2: Experimental observations in optical, chemical, and thermoreflectance spectroscopy

    Directory of Open Access Journals (Sweden)

    Ching-Hwa Ho

    2012-06-01

    Full Text Available Optical examination of a chaocogenide compound AgAlS2 which can spontaneously transfer to a AgAlO2 oxide has been investigated by thermoreflectance (TR spectroscopy herein. The single crystals of AgAlS2 were grown by chemical vapor transport (CVT method using ICl3 as a transport agent sealed in evacuated quartz tubes. The as-grown AgAlS2 crystals essentially possess a transparent and white color in vacuum. The crystal surface of AgAlS2 becomes darkened and brownish when putting AgAlS2 into atmosphere for reacting with water vapor or hydrogen gas. Undergoing the chemical reaction process, oxygen deficient AgAlO2-2x with brownish and reddish-like color on surface of AgAlS2 forms. The transition energy of deficient AgAlO2-2x was evaluated by TR experiment. The value was determined to be ∼2.452 eV at 300 K. If the sample is kept dry and moved away from moisture, AgAlS2 crystal can stop forming more deficient AgAlO2-2x surface oxides. The experimental TR spectra for the surface-reacted sample show clearly two transition features at EW=2.452 eV for deficient AgAlO2-2x and EU=3.186 eV for AgAlS2, respectively. The EU transition belongs to direct band-edge exciton of AgAlS2. Alternatively, for surface-oxidation process of AgAlS2 lasting for a long time, a AgAlO2 crystal with yellowish color will eventually form. The TR measurements show mainly a ground-state band edge exciton of E OX 1 detected for AgAlO2. The energy was determined to be E OX 1=2.792 eV at 300 K. The valence-band electronic structure of AgAlS2 has been detailed characterized using polarized-thermoreflectance (PTR measurements in the temperature range between 30 and 340 K. Physical chemistry behaviors of AgAlS2 and AgAlO2 have been comprehensively studied via detailed analyses of PTR and TR spectra. Based on the experimental analyses, optical and chemical behaviors of the AgAlS2 crystals under atmosphere are realized. A possible optical-detecting scheme for using AgAlS2 as a humidity

  20. High-performance flexible surface-enhanced Raman scattering substrates fabricated by depositing Ag nanoislands on the dragonfly wing

    Science.gov (United States)

    Wang, Yuhong; Wang, Mingli; Shen, Lin; Sun, Xin; Shi, Guochao; Ma, Wanli; Yan, Xiaoya

    2018-04-01

    Natural dragonfly wing (DW), as a template, was deposited on noble metal sliver (Ag) nanoislands by magnetron sputtering to fabricate a flexible, low-cost, large-scale and environment-friendly surface-enhanced Raman scattering (SERS) substrate (Ag/DW substrate). Generally, materials with regular surface nanostructures are chosen for the templates, the selection of our new material with irregular surface nanostructures for substrates provides a new idea for the preparation of high-performance SERS-active substrates and many biomimetic materials. The optimum sputtering time of metal Ag was also investigated at which the prepared SERS-active substrates revealed remarkable SERS activities to 4-aminothiophenol (4-ATP) and crystal violet (CV). Even more surprisingly, the Ag/DW substrate with such an irregular template had reached the enhancement factor (EF) of ∼1.05 × 105 and the detection limit of 10-10 M to 4-ATP. The 3D finite-different time-domain (3D-FDTD) simulation illustrated that the "hot spots" between neighbouring Ag nanoislands at the top of pillars played a most important role in generating electromagnetic (EM) enhancement and strengthening Raman signals.

  1. Advanced surface characterization of silver nanocluster segregation in Ag-TiCN bioactive coatings by RBS, GDOES, and ARXPS.

    Science.gov (United States)

    Escobar Galindo, R; Manninen, N K; Palacio, C; Carvalho, S

    2013-07-01

    Surface modification by means of wear protective and antibacterial coatings represents, nowadays, a crucial challenge in the biomaterials field in order to enhance the lifetime of bio-devices. It is possible to tailor the properties of the material by using an appropriate combination of high wear resistance (e.g., nitride or carbide coatings) and biocide agents (e.g., noble metals as silver) to fulfill its final application. This behavior is controlled at last by the outmost surface of the coating. Therefore, the analytical characterization of these new materials requires high-resolution analytical techniques able to provide information about surface and depth composition down to the nanometric level. Among these techniques are Rutherford backscattering spectrometry (RBS), glow discharge optical emission spectroscopy (GDOES), and angle resolved X-ray photoelectron spectroscopy (ARXPS). In this work, we present a comparative RBS-GDOES-ARXPS study of the surface characterization of Ag-TiCN coatings with Ag/Ti atomic ratios varying from 0 to 1.49, deposited at room temperature and 200 °C. RBS analysis allowed a precise quantification of the silver content along the coating with a non-uniform Ag depth distribution for the samples with higher Ag content. GDOES surface profiling revealed that the samples with higher Ag content as well as the samples deposited at 200 °C showed an ultrathin (1-10 nm) Ag-rich layer on the coating surface followed by a silver depletion zone (20-30 nm), being the thickness of both layers enhanced with Ag content and deposition temperature. ARXPS analysis confirmed these observations after applying general algorithm involving regularization in addition to singular value decomposition techniques to obtain the concentration depth profiles. Finally, ARXPS measurements were used to provide further information on the surface morphology of the samples obtaining an excellent agreement with SEM observations when a growth model of silver islands with

  2. [Characteristics of HBV transmission in families with HBsAg-positive fathers and familial clustering of HBV infection].

    Science.gov (United States)

    Yang, Y; Jin, L; He, Y L; Liu, J F; Wang, J; Wang, K; Ma, X H; Li, Q; Feng, Y L; Yan, Z; Yi, R T; Chen, T Y; Zhao, Y R

    2016-04-01

    To investigate the characteristics of hepatitis B virus (HBV) transmission among family members in families with familial clustering of HBV infection and poor outcomes, as well as the prevalence and distribution characteristics of HBsAg in offspring with different parental HBsAg status. The general information of each member in families with poor outcomes were collected from 2007 to 2010, and serological test was performed to analyze the prevalence and distribution of HBsAg in family members. The chi-square test or Fisher's exact test was used to analyze and compare the sex of offspring and the prevalence of HBsAg in them in 266 nuclear families with different paternal and maternal HBsAg status. The positive rates of HBsAg in parents, siblings, children, and spouses of the probands were 20%, 88.2%, 76.8%, and 9.5%, respectively. The nuclear families with HBsAg-positive fathers and HBsAg-negative mothers had a significantly increased proportion of male offspring (male/female ratio = 2.02) compared with those with HBsAg-positive mothers and HBsAg-negative fathers (1.22) or those with HBsAg-negative fathers and mothers (0.96). In addition, in the nuclear families with HBsAg-positive fathers and HBsAg-negative mothers, the male offspring had a significantly higher HBsAg positive rate than female offspring (37.4% vs 13.8%), while in those with HBsAg-positive mothers and HBsAg-negative fathers or those with HBsAg-negative fathers and mothers, HBsAg positive rate showed no significant difference between male and female offspring. In families with familial clustering of HBV infection and poor outcomes, mother-to-child transmission is still the major route of HBV transmission, but father-to-child transmission also plays a role in HBV transmission in this special population. Positive HBsAg in fathers is associated with the increased proportion of male offspring, and father-to-son transmission of HBV is higher than father-to-daughter transmission.

  3. Reliable lateral manipulation of a single Ag adatom on a Ag(1 1 1) surface with a trimer-apex tip

    International Nuclear Information System (INIS)

    Xie Yiqun; Shi Wangzhou; Du Guoping

    2009-01-01

    We study the reliability of the lateral manipulation of a single Ag adatom on a Ag(1 1 1) surface with the single-atom and trimer-apex tips based on molecular statics simulations using surface embedded-atom-method potential. The dependence of the manipulation reliability on tip height and orientation is investigated. For the single-atom tip the manipulation reliability increases monotonically with decreasing tip height, which is owing to the strengthened lateral tip-adatom interaction as the tip height lowers. For the trimer-apex tip, the manipulation reliability is sensitive to the tip orientation in the lower tip-height range, while in the higher tip-height range the manipulation reliability is independent of the tip orientation and moreover can be greatly improved due to the strong vertical attraction of the tip on the adatom as compared to the single-atom tip. We also compare these results to those for manipulating single Cu adatoms on the Cu(1 1 1) surface, reveal the underlying physics, and propose the method to improve the manipulation reliability for different systems.

  4. Tailoring the morphology and electrocatalytic properties of electrochemically formed Ag/TiO2 composite deposits on titanium surfaces

    Directory of Open Access Journals (Sweden)

    S. V. MENTUS

    2007-12-01

    Full Text Available Three different forms of Ag/TiO2 composite layers, which have whisker-, dot- and island-like distribution of silver were obtained on a mechanically polished titanium surface by adjusting the conditions of silver deposition from an aqueous AgNO3 solution. The deposit morphology was the result of both the program of electrode polarization and the template action of the simultaneously formed TiO2 layer. The catalytic activity of the composite layers toward the oxygen reduction reaction was studied in aqueous 0.1 M NaOH solutions and found to be a function of both the surface loading of silver and the type of silver distribution within the Ag/TiO2 composite layers. The reaction path of oxygen reduction on the composite layers was found to be always a 4e- one, characteristic otherwise of polycrystalline silver electrodes.

  5. Effect of Ag-doping of nanosized FeAlO system on its structural, surface and catalytic properties

    Directory of Open Access Journals (Sweden)

    Laila I. Ali

    2016-11-01

    Full Text Available The effects of Ag2O-doping on the physicochemical, surface and catalytic properties of FeAlO system with various extents of Fe2O3 loading have been investigated. The dopant concentration was changed between 1.5 and 4.0 mol % Ag2O. Pure and variously doped solids were subjected to heat treatment at 400–800 °C. The techniques employed for characterization of catalysts were TG/DTG, XRD, N2-adsorption at −196 °C and the catalytic decomposition of H2O2 at 25–40 °C. The results obtained revealed that, the investigated catalysts consisted of nanosized γ-Al2O3 phase. The textural properties including SBET, porosity and St were modified by Ag2O-doping. The doping process with Ag-species improves the catalytic activity of FeAlO system. Increasing the precalcination temperature from 400 to 800 °C increases the catalytic activity of 3.5% AgFeAlO with 1.9-fold toward H2O2 decomposition at 30 °C. Furthermore, the maximum increase in the catalytic activity due to doping with 3.5 mol % Ag2O at 30 °C attained about 15.1-fold for the solids calcined at 800 °C.

  6. Ag/Bi2MoO6-x with enhanced visible-light-responsive photocatalytic activities via the synergistic effect of surface oxygen vacancies and surface plasmon

    Science.gov (United States)

    Wang, Danjun; Shen, Huidong; Guo, Li; Wang, Chan; Fu, Feng; Liang, Yucang

    2018-04-01

    In this study, a heterostructured Ag/Bi2MoO6-x photocatalyst was rationally designed and successfully fabricated via the deposition of plasmonic silver nanoparticles onto the surface of Bi2MoO6 with surface oxygen vacancy (denoted as Bi2MoO6-x). Bi2MoO6-x (Abbr. BMO6-x was first synthesized via a solvothermal synthesis and calcination process. The plasmonic silver nanoparticles were then loaded onto the surface of BMO6-x using a simple photoreduction process to form Ag/BMO6-x composite. Surface oxygen vacancies (SOVs) in BMO6-x were confirmed by electron paramagnetic resonance (EPR) spectrum. The structures of BMO6-xand Ag/BiMoO6-x) were characterized using high-resolution transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy. Under visible light irradiation, sample Ag/BMO6-x exhibits a highest visible-light-responsive photocatalytic performance compared to those of pure-Bi2MoO6 (BMO), BMO6-x and Ag/BMO for the degradation of rhodamine B (RhB), which is attributed predominantly to the synergistic effect of SOVs and Ag surface plasmonic resonance (SPR) on the surface of Bi2MoO6-x leading to the efficient separation and migration of photogenerated electrons/holes and hence broadening light responsive region. The significant improvement of the migration and separation of photogenerated electrons/holes in the Ag/BMO6-x was evidenced by photoluminescence spectra, time-resolved fluorescence decay, photocurrent, and electrochemical impedance spectrum. The ESR with spin-trap technique and reactive species trapping experiments confirm that the mainly active species O2- and h+ are playing key roles in the RhB photodegradation process over Ag/BMO6-x. This study not only provides an understandable synergistic effect of SOVs and SPR Ag but also pioneers a new approach for fabricating a series of highly catalytically active metal-semiconductor photocatalysts with surface atom defects.

  7. Hepatitis B surface antigen variants in voluntary blood donors in Nanjing, China

    Directory of Open Access Journals (Sweden)

    Yong-lin Yang

    2012-04-01

    Full Text Available Abstract Background Hepatitis B virus (HBV is still one of the serious infectious risks for the blood transfusion safety in China. One plausible reason is the emergence of the variants in the major antigenic alpha determinant within the major hydrophilic region (MHR of hepatitis B surface antigen (HBsAg, which have been assumed to evade the immune surveillance and pose a challenge to the disease diagnosis. It is well documented that some commercial ELISA kits could detect the wild-type but not the mutant viruses. The high prevalence of HBV in China also impaired the application of nucleic acid testing (NAT in the improvement of blood security. Molecular epidemiological study of HBsAg variations in China is still limited. This study was designed to identify the prevalence of mutations in the HBsAg in voluntary blood donors in Nanjing, China. Methods A total of 20,326 blood units were enrolled in this study, 39 donors were positive for HBV S gene in the nested-PCR. Mutations in the major hydrophilic region (MHR; aa 99-169 were identified by direct sequencing of S region. Results Among of 20,326 blood units in the Red Cross Transfusion Center of Nanjing from October 2008 to April 2009, 296 samples (1.46%, 296/20,326 were HBsAg positive in the 2 successive rounds of the ELISA test. In these HBsAg positive units, HBV S gene could be successfully amplified from 39 donors (13.18%, 39/296 in the nested-PCR. Sequence analysis revealed that 32 strains (82.1%, 32/39 belong to genotype B, 7 strains (17.9%, 7/39 to genotype C. Besides well known G145R, widely dispersed variations in the MHR of S region, were observed in 20 samples of all the strains sequenced. Conclusions HBV/B and HBV/C are dominant in Nanjing, China. The mutations in the MHR of HBsAg associated with disease diagnosis are common.

  8. Fabrication of Ag/ZnO heterostructure and the role of surface coverage of ZnO microrods by Ag nanoparticles on the photophysical and photocatalytic properties of the metal-semiconductor system

    Science.gov (United States)

    Sarma, Bikash; Sarma, Bimal K.

    2017-07-01

    This report presents findings on microstructural, photophysical, and photocatalytic properties of Ag/ZnO heterostructure grown on flexible and silicon substrates. ZnO microrods are prepared by thermal decomposition method for different solute concentrations and Ag/ZnO heterostructure are fabricated by photo-deposition of Ag nanoparticles on ZnO microrods. X-ray diffraction and electron microscopy studies confirm that ZnO microrods belong to the hexagonal wurtzite structure and grown along [001] direction with random alignment showing that majority microrods are aligned with (100) face parallel to the sample surface. Plasmonic Ag nanoparticles are attached to different faces of ZnO. In the optical reflection spectra of Ag/ZnO heterostructure, the surface plasmon resonance peak due to Ag nanoparticles appears at 445 nm. Due to the oxygen vacancies the band gaps of ZnO microrods turn out to be narrower compared to that of bulk ZnO. The presence of Ag nanoparticles decreases the photoluminescence intensity which might be attributed to the non-radiative energy and direct electron transfer in the plasmon-exciton system. The quenching of photoluminescence in Ag/ZnO heterostructure at different growth conditions depend on the extent of surface coverage of ZnO by plasmonic Ag nanoparticles. Photocatalytic degradation efficiency of Ag/ZnO heterostructure is higher than that of ZnO microrods. The extent of surface coverage of ZnO microrods by Ag nanoparticles is crucial for the observed changes in photophysical and photochemical properties.

  9. Microstructure, Surface Characterization, and Electrochemical Behavior of New Ti-Zr-Ta-Ag Alloy in Simulated Human Electrolyte

    Science.gov (United States)

    Vasilescu, Cora; Drob, Silviu Iulian; Osiceanu, Petre; Moreno, Jose Maria Calderon; Prodana, Mariana; Ionita, Daniela; Demetrescu, Ioana; Marcu, Maria; Popovici, Ion Alexandru; Vasilescu, Ecaterina

    2017-01-01

    A new Ti-20Zr-5Ta-2Ag alloy was elaborated and characterized regarding its microstructure, its native passive film composition and thickness, its surface wettability, its electrochemical behavior in Ringer solution of different pH values, and its ion release. The new alloy has a bi-phase, α + β, acicular, homogeneous microstructure (scanning electron microscopy (SEM)). Its native passive film (12-nm thicknesses) consists of the protective TiO2, ZrO2, and Ta2O5 oxides, Ti and Ta suboxides, and metallic Ag (X-ray photoelectron spectroscopy (XPS) data). The alloy possesses high hydrophilic properties. The main electrochemical parameters of the new alloy are superior to those of Ti as a result of the beneficial influence of Zr, Ta, and Ag alloying elements, which reinforce its native passive film. Electrochemical impedance spectroscopy (EIS) spectra in Ringer solutions for the new alloy displayed better values of impedances and phase angles, proving a more insulate passive film than that on the Ti surface. The main corrosion parameters for the new Ti-20Zr-5Ta-2Ag alloy are more favorable by about 25 to 38 times than those of Ti, confirming extremely resistant passive film. The new Ti-20Zr-5Ta-2Ag alloy releases into Ringer solution low quantities of Ti4+, Zr4+ metallic ions (inductively coupled plasma-mass spectroscopy (ICP-MS)). The Ag+ ions are released in low quantity, conferring to this alloy's low antibacterial activity. All experimental results show that the new Ti-20Zr-5Ta-2Ag alloy fulfills the requirements for biocompatibility, corrosion resistance, and antibacterial protection.

  10. sero-prevalence of hepatitis b surface antigen (hbsag)

    African Journals Online (AJOL)

    DR. AMINU

    of drugs, alcoholism, chemicals and environmental ... blood, serum, vaginal secretions and in saliva though in low concentrations (Lindsley et al., 1990). Although surrounded by a host cell derived envelope, HBV is remarkably stable to organic solvents. It is also heat and pH – resistant (Holling et al., 1995). Young children ...

  11. Replacement of Poly(vinyl pyrrolidone) by Thiols: A Systematic Study of Ag Nanocube Functionalization by Surface-Enhanced Raman Scattering

    OpenAIRE

    Moran, Christine H.; Rycenga, Matthew; Zhang, Qiang; Xia, Younan

    2011-01-01

    In this work, we used surface-enhanced Raman scattering (SERS) to monitor the replacement of poly(vinyl pyrrolidone) (PVP) on Ag nanocubes by cysteamine, thiol-terminated PEG, and benzenedithiol. PVP is widely used as a colloidal stabilizer and capping agent to control the shape of Ag (as well as many other noble metals) nanocrystals during synthesis, and to stabilize the final colloidal suspension. However, the surface chemistry of Ag nanocrystals often needs to be tailored for specific appl...

  12. Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition

    OpenAIRE

    Lu, Xiong; Zhang, Bailin; Wang, Yingbo; Zhou, Xianli; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio; Ding, Yonghui; Leng, Yang

    2010-01-01

    Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we...

  13. Investigation on surface, electrical and optical properties of ITO-Ag-ITO coated glass

    International Nuclear Information System (INIS)

    Aslan Necdet; Sen, Tuba; Coruhlu Turgay; Senturk Kenan; Keskin Sinan; Seker Sedat; Dobrovolskiy Andrey

    2015-01-01

    The aim of this work was to study the optical and electrical properties of thick ITO-Ag-ITO multilayer coating onto glass. ITO-Ag-ITO coatings with thickness of ITO layers 110 nm, 185 nm and intermediate Ag layer thickness 40 nm were prepared by magnetron sputtering. The optical, electrical and atomic properties of the coating were examined by scanning electron microscope, atomic force microscope, X-ray diffraction analysis and ultraviolet-visible spectroscopy

  14. Prevalence of Hepatitis B Surface Antigen in US-Born and Foreign-Born Asian/Pacific Islander College Students

    Science.gov (United States)

    Quang, Yen N.; Vu, Joanne; Yuk, Jihey; Li, Chin-Shang; Chen, Moon; Bowlus, Christopher L.

    2010-01-01

    The prevalence of chronic hepatitis B (HBV) among college-age US-born Asian and Pacific Islanders (A/PI) is not well known. Objectives: To compare the prevalence of hepatitis B surface antigen (HBsAg) seropositivity in US-born to A/PI-born students at a public university. Participants: Undergraduate who self-identified themselves as A/PI. Results:…

  15. Disposable immunoassay for hepatitis B surface antigen based on a graphene paste electrode functionalized with gold nanoparticles and a Nafion-cysteine conjugate

    International Nuclear Information System (INIS)

    Huang, K.-J.; Li, J.; Liu, Y.-M.; Yu, S.; Yu, M.; Cao, X.

    2012-01-01

    We report on the modification of a graphene paste electrode with gold nanoparticles (AuNPs) and a Nafion-L-cysteine composite film, and how this electrode can serve as a platform for the construction of a novel electrochemical immunosensor for the detection of hepatitis B surface antigen (HBsAg). To obtain the immunosensor, an antibody against HBsAg was immobilized on the surface of the electrode, and this process was followed by cyclic voltammetry and electrochemical impedance spectroscopy. The peak currents of a hexacyanoferrate redox system decreased on formation of the antibody-antigen complex on the surface of the electrode. Then increased electrochemical response is thought to result from a combination of beneficial effects including the biocompatibility and large surface area of the AuNPs, the high conductivity of the graphene paste electrode, the synergistic effects of composite film, and the increased quantity of HBsAb adsorbed on the electrode surface. The differential pulse voltammetric responses of the hexacyanoferrate redox pair are proportional to the concentration of HBsAg in the range from 0. 5-800 ng mL -1 , and the detection limit is 0.1 ng mL -1 (at an S/N of 3). The immunosensor is sensitive and stable. (author)

  16. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)

    OpenAIRE

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-01-01

    Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a stro...

  17. Influence of Cu, Au and Ag on structural and surface properties of bioactive coatings based on titanium.

    Science.gov (United States)

    Wojcieszak, D; Mazur, M; Kalisz, M; Grobelny, M

    2017-02-01

    In this work influence of copper, silver and gold additives on structural and surface properties of biologically active thin films based on titanium have been described. Coatings were prepared by magnetron sputtering method. During each process metallic discs (targets) - Ti and the additive (Cu, Ag or Au) were co-sputtered in argon atmosphere. Structural investigation of as-deposited coatings was performed with the aid of XRD and SEM/EDS method. It was found that all prepared thin films were homogenous. Addition of Cu, Ag and Au resulted in nanocrystalline structure. Moreover, influence of these additives on hardness and antibacterial activity of titanium coatings was also studied. Ti-Cu, Ti-Ag and Ti-Au films had lower hardness as-compared to Ti. According to AAS results the difference of their activity was related to the ion migration process. It was found that Ti-Ag and Ti-Au coatings had biocidal effect related to direct contact of their surface with microorganisms. In the case of Ti-Cu antimicrobial activity had direct and indirect nature due to efficient ion migration process from the film surface to the surrounding environment. Functional features of coatings such as wettability and corrosion resistance were also examined and included in the comprehensive analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. A molecular analysis of viral persistence in surface antigen-negative chronic hepatitis B.

    Science.gov (United States)

    Kato, J; Hasegawa, K; Torii, N; Yamauchi, K; Hayashi, N

    1996-03-01

    To identify the mechanisms of viral persistence in patients with chronic hepatitis B after the acquisition of anti-hepatitis B surface antigen antibodies (antiHBs), we serially analyzed the nucleotide sequence of the envelope region in a cohort of infected patients. Four patients with histological diagnoses of chronic hepatitis B who had at least 5 years of observance by our hospital staff were studied. All but one showed normalization of serum alanine aminotransferase (ALT) concentration after clearance of the hepatitis B surface of antigen (HBsAg) and the appearance of anti-HBs. Hepatitis B virus (HBV) DNA was still detectable by polymerase chain reaction (PCR) amplification assay in serum specimens from two patients, even in the presence of circulating anti-HBs. The envelope gene was amplified by PCR in serum samples obtained both before and after seroconversion, and direct cycle sequencing of the PCR products was performed. A mutation resulting in a premature stop codon was found in the pre-S1 region of one patient just prior to clearance of HBsAg. Two years later, the stop codon was converted to a leucine codon and three mutations developed in the "a" loop. In the other patient, 16 amino acids had been deleted between amino acids 8 and 23 in the pre-S2 region before clearance of HBsAg. After the appearance of circulating anti-HBs, the pre-S2 gene reverted to the wild type but three additional mutations appeared inside the "a" loop. These results suggest that HBV mutates when HBsAg is cleared, which may contribute to viral persistence due to an evasion of the host immune surveillance.

  19. Synthesis of Au@Ag core-shell nanocubes containing varying shaped cores and their localized surface plasmon resonances.

    Science.gov (United States)

    Gong, Jianxiao; Zhou, Fei; Li, Zhiyuan; Tang, Zhiyong

    2012-06-19

    We have synthesized Au@Ag core-shell nanocubes containing Au cores with varying shapes and sizes through modified seed-mediated methods. Bromide ions are found to be crucial in the epitaxial growth of Ag atoms onto Au cores and in the formation of the shell's cubic shape. The Au@Ag core-shell nanocubes exhibit very abundant and distinct localized surface plasmon resonance (LSPR) properties, which are core-shape and size-dependent. With the help of theoretical calculation, the physical origin and the resonance mode profile of each LSPR peak are identified and studied. The core-shell nanocrystals with varying shaped cores offer a new rich category for LSPR control through the plasmonic coupling effect between core and shell materials.

  20. Assessing stability and assembly of the hepatitis B surface antigen into virus-like particles during down-stream processing.

    Science.gov (United States)

    Zahid, Maria; Lünsdorf, Heinrich; Rinas, Ursula

    2015-07-17

    The hepatitis B surface antigen (HBsAg) is a recombinant protein-based vaccine being able to form virus-like particles (VLPs). HBsAg is mainly produced using yeast-based expression systems, however, recent results strongly suggest that VLPs are not formed within the yeast cells during the cultivation but are formed in a gradual manner during the following down-stream procedures. VLPs are also not detectable during the first down-stream steps including mechanical and EDTA/detergent-assisted cell destruction. Moreover, VLPs are not detectable in the cell lysate treated with polyethylene glycol and colloidal silica. The first VLP resembling structures appear after elution of HBsAg from colloidal silica to which it binds through hydrophobic interaction. These first VLP resembling structures are non-symmetrical as well as heterodisperse and exhibit a high tendency toward cluster formation presumably because of surface exposed hydrophobic patches. More symmetrical and monodisperse VLPs appear after the following ion-exchange and size-exclusion chromatography most likely as the result of buffer changes during these purification steps (toward more neutral pH and less salt). Final treatment of the VLPs with the denaturant KSCN at moderate concentrations with following KSCN removal by dialysis does not cause unfolding and VLP disassembly but results in a re- and fine-structuring of the VLP surface topology. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Lamivudine monoprophylaxis for de novo HBV infection in HBsAg-negative recipients with HBcAb-positive liver grafts.

    Science.gov (United States)

    Vizzini, Giovanni; Gruttadauria, Salvatore; Volpes, Riccardo; D'Antoni, Adele; Pietrosi, Giada; Filì, Daniela; Petridis, Ioannis; Pagano, Duilio; Tuzzolino, Fabio; Santonocito, M Maria; Gridelli, Bruno

    2011-01-01

    We followed the efficacy of long-term lamivudine monotherapy in preventing development of de novo hepatitis B (DNHB) in a large cohort of hepatitis B surface antigen (HBsAg)-negative recipients with grafts from hepatitis B core antibody (HBcAb)-positive donors. Recipients were observed over a long follow-up. Between July 1999 and December 2008, 45 patients (median age 54, range 19-67) who were HBsAg negative before transplantation were included in the study of monoprophylaxis with lamivudine starting on post-operative day 1, and continuing for life. Mean follow-up: 37.9 months; median 32.1 months (range 2.4-117). No suspension of therapy was reported during the study. Post-transplantation, no DNHB was observed in follow-up: all 45 HBsAg-negative recipients remained HBsAg and HBV DNA negative. Thirty-four of these HBsAg-negative recipients were alive at conclusion of the study. A total of 11 patients died, five of HCV recurrence, two of hepatocellular carcinoma (HCC) recurrence, two of disseminated KSV infection, and two of multiorgan failure because of early graft dysfunction. Patient and graft survival of HBsAg-negative recipients with HBcAb-positive donor grafts (45 cases) were not significantly different from those of the HBsAg-negative recipients with HBcAb-negative donor grafts (302 cases). In our experience, lamivudine monoprophylaxis provided complete protection against HBV reactivation and showed long-term efficacy. © 2010 John Wiley & Sons A/S.

  2. Swift heavy ions induced surface modifications in Ag-polypyrrole composite films synthesized by an electrochemical route

    International Nuclear Information System (INIS)

    Kumar, Vijay; Ali, Yasir; Sharma, Kashma; Kumar, Vinod; Sonkawade, R.G.; Dhaliwal, A.S.; Swart, H.C.

    2014-01-01

    Highlights: • Two steps electrochemical synthesis for the fabrication of Ag-polypyrrole composite films. • Surface modifications by swift heavy ion beam. • SEM image shows the formation of craters and humps after irradiation. • Detailed structural analysis by Raman spectroscopy. - Abstract: The general aim of this work was to study the effects of swift heavy ions on the properties of electrochemically synthesized Ag-polypyrrole composite thin films. Initially, polypyrrole (PPy) films were electrochemically synthesized on indium tin oxide coated glass surfaces using a chronopotentiometery technique, at optimized process conditions. The prepared PPy films have functioned as working electrodes for the decoration of submicron Ag particles on the surface of the PPy films through a cyclicvoltammetry technique. Towards probing the effect of swift heavy ion irradiation on the structural and morphological properties, the composite films were subjected to a 40 MeV Li 3+ ion beam irradiation for various fluences (1 × 10 11 , 1 × 10 12 and 1 × 10 13 ions/cm 2 ). Comparative microstructural investigations were carried out after the different ion fluences using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy and micro-Raman spectroscopy techniques. Raman and SEM studies revealed that the structure of the films became disordered after irradiation. The SEM studies of irradiated composite films show significant changes in their surface morphologies. The surface was smoother at lower fluence but craters were observed at higher fluence

  3. Swift heavy ions induced surface modifications in Ag-polypyrrole composite films synthesized by an electrochemical route

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay, E-mail: vijays_phy@rediffmail.com [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Ali, Yasir [Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal, District Sangrur 148106, Punjab (India); Sharma, Kashma [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Department of Chemistry, Shoolini University of Biotechnology and Management Sciences, Solan 173212 (India); Kumar, Vinod [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Sonkawade, R.G. [Inter University Accelerator Center, Aruna Asif Ali Marg, New Delhi 110067 (India); Dhaliwal, A.S. [Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal, District Sangrur 148106, Punjab (India); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa)

    2014-03-15

    Highlights: • Two steps electrochemical synthesis for the fabrication of Ag-polypyrrole composite films. • Surface modifications by swift heavy ion beam. • SEM image shows the formation of craters and humps after irradiation. • Detailed structural analysis by Raman spectroscopy. - Abstract: The general aim of this work was to study the effects of swift heavy ions on the properties of electrochemically synthesized Ag-polypyrrole composite thin films. Initially, polypyrrole (PPy) films were electrochemically synthesized on indium tin oxide coated glass surfaces using a chronopotentiometery technique, at optimized process conditions. The prepared PPy films have functioned as working electrodes for the decoration of submicron Ag particles on the surface of the PPy films through a cyclicvoltammetry technique. Towards probing the effect of swift heavy ion irradiation on the structural and morphological properties, the composite films were subjected to a 40 MeV Li{sup 3+} ion beam irradiation for various fluences (1 × 10{sup 11}, 1 × 10{sup 12} and 1 × 10{sup 13} ions/cm{sup 2}). Comparative microstructural investigations were carried out after the different ion fluences using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy and micro-Raman spectroscopy techniques. Raman and SEM studies revealed that the structure of the films became disordered after irradiation. The SEM studies of irradiated composite films show significant changes in their surface morphologies. The surface was smoother at lower fluence but craters were observed at higher fluence.

  4. Improved humoral and cellular immune response against the gp120 V3 loop of HIV-1 following genetic immunization with a chimeric DNA vaccine encoding the V3 inserted into the hepatites B surface antigen

    DEFF Research Database (Denmark)

    Fomsgaard, A.; Nielsen, H.V.; Bryder, K.

    1998-01-01

    -2d-restricted cytotoxic T lymphocyte (CTL) epitope. In an attempt to improve the immunogenicity of V3 in DNA vaccines, a plasmid expressing MN V3 as a fusion protein with the highly immunogenic middle (pre-S2+S) surface antigen of hepatitis B virus (HBsAg) was constructed. Epidermal inoculation...... by gene gun was used for genetic immunization in a mouse model. Antibody and CTL responses to MN V3 and HBsAg were measured and compared with the immune responses obtained after vaccination with plasmids encoding the complete HIV-1 MN gp160 and HBsAg (pre-S2+S), respectively. DNA vaccination with the HIV...... MN gp160 envelope plasmid induced a slow and low titred anti-MN V3 antibody response at 12 weeks post-inoculation (p.i.) and a late appearing (7 weeks), weak and variable CTL response. In contrast, DNA vaccination with the HBsAg-encoding plasmid induced a rapid and high titred anti-HBsAg antibody...

  5. A facile and green method for synthesis of reduced graphene oxide/Ag hybrids as efficient surface enhanced Raman scattering platforms.

    Science.gov (United States)

    Huang, Qingli; Wang, Jiaming; Wei, Wenxian; Yan, Qiuxiang; Wu, Changle; Zhu, Xiashi

    2015-01-01

    Reduced graphene oxide/Ag nanoparticles hybrids (rGO/AgNPs) were fabricated via a green and facile hydrothermal method. The as-synthesized materials were characterized in detail using various spectroscopic and microscopic techniques. Under a suitable dosage of silver ions, well-dispersed AgNPs on the reduced graphene oxide sheets were obtained. The surface plasmon resonance properties of AgNPs on graphene show that there is an interaction between AgNPs and graphene. Trace detection of organic dyes is studied based on rGO/AgNPs hybrids as efficient surface enhanced Raman scattering platforms. It has been found that the suitable experiment parameter is crucial to trace detection of organic dyes molecules. This work is of importance in the practical application in device-design based on the SERS effect of noble metal/reduced oxide graphene (or oxide graphene) hybrids. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Disinfection of Escherichia coli Gram negative bacteria using surface modified TiO2: optimization of Ag metallization and depiction of charge transfer mechanism.

    Science.gov (United States)

    Gomathi Devi, LakshmipathiNaik; Nagaraj, Basavalingaiah

    2014-01-01

    The antibacterial activity of silver deposited TiO2 (Ag-TiO2 ) against Gram negative Escherichia coli bacteria was investigated by varying the Ag metal content from 0.10 to 0.50% on the surface of TiO2 . Ag depositions by the photoreduction method were found to be stable. Surface silver metallization was confirmed by EDAX and XPS studies. Photoluminescence studies show that the charge carrier recombination is less for 0.1% Ag-TiO2 and this catalyst shows superior bactericidal activity under solar light irradiation compared to Sol gel TiO2 (SG-TiO2 ) due to the surface plasmon effect. The energy levels of deposited Ag are dependent on the Ag content and it varies from -4.64 eV to -1.30 eV with respect to the vacuum energy level based on atomic silver to bulk silver deposits. The ability of electron transfer from Ag deposit to O2 depends on the position of the energy levels. The 0.25% and 0.50% Ag depositions showed detrimental effect on bactericidal activity due to the mismatch of energy levels. The effect of the EROS (External generation of the Reactive Oxygen Species by 0.1% Ag-TiO2 ) and IROS (Interior generation of Reactive Oxygen Species within the bacteria) on the bactericidal inactivation is discussed in detail. © 2014 The American Society of Photobiology.

  7. Si(111)-sq root 21 x sq root 21 -(Ag+Cs) surface studied by scanning tunneling microscopy and angle-resolved photoemission spectroscopy

    CERN Document Server

    Liu, C; Morikawa, H; Okino, H; Hasegawa, S; Okuda, T; Kinoshita, T

    2003-01-01

    Scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) were used to study the atomic and electronic structures of the Si(111)-sq root 21 x sq root 21-(Ag + Cs) surface (sq root 21-Cs in short), which was induced by depositing caesium atoms on the Si(111)-sq root 3 x sq root 3-Ag surface at room temperature (RT). Compared with previously reported STM images of noble-metal induced sq root 21 x sq root 21 phases including the Si(111)-sq root 21 x sq root 21-(Ag+Ag) and Si(111)-sq root 21 x sq root 21-(Ag+Au) surfaces (sq root 21-Ag and sq root 21-Au, respectively), the sq root 21-Cs surface displayed quite different features in STM images. The ARPES data of the sq root 21-Cs surface revealed an intrinsic dispersive surface-state band, together with a non-dispersive one near the Fermi level, which was also different from those of the sq root 21-Ag and sq root 21-Au surfaces. These results strongly suggest different atomic arrangements between Cs- and noble-metal induced sq root ...

  8. Dysregulated Response of Follicular Helper T cells to Hepatitis B Surface Antigen Promotes HBV Persistence in Mice and Associates With Outcomes of Patients.

    Science.gov (United States)

    Wang, Xiaowen; Dong, Qingyang; Li, Qian; Li, Yuanyuan; Zhao, Dianyuan; Sun, Jinjie; Fu, Junliang; Meng, Fanping; Lin, Hu; Luan, Junjie; Liu, Biao; Wang, Min; Wang, Fusheng; He, Fuchu; Tang, Li

    2018-03-12

    Production of neutralizing antibodies against hepatitis B surface antigen (HBsAg) is dysregulated in patients with persistent hepatitis V virus (HBV) infection. We investigated mechanisms by which this immune response to the virus is disrupted and whether it can be restored to promote clearance of HBV. Immune-competent C57BL/6N and C57BL/6J, as well as mice deficient in follicular helper T cells (Tfh cell-deficient), B cells, or Foxp3 + T-regulatory cells (Treg cell-deficient), were given hydrodynamic injections of pAAV/HBV1.2 plasmids. Some mice were given injections of sorted Tfh cells, pan-B cells, Treg cells, or a blocking antibody against CTLA4. Production of antibodies against HBsAg and clearance of HBV were assessed by flow cytometry, ELISA, PCR and immunohistochemical analyses. We obtained blood samples from patients with HBV infection and isolated Treg cells. We measured the ability of Treg cells to suppress production of interleukin 21 (IL21) in CD4 + T cells. Immune-competent C57BL/6N and C57BL/6J mice transfected with the plasmid encoding HBV had features of viral clearance and viral persistence observed in humans. A Tfh-cell response to HBsAg was required for clearance of HBV and was suppressed by Treg cells in mice with persistent HBV infection. Depletion of Treg cells or inhibition of Treg-cell function (with blocking antibody against CTLA4) restored the Tfh-cell response against HBsAg and clearance of HBV in mice. Impaired Tfh cell response to HBsAg was observed in blood from patients with chronic HBV infection, responsiveness was restored by depletion of Treg cells or blocking antibody against CTLA4. In studies of HBV-infected mice and blood from patients with chronic HBV infection, we found a Tfh-cell response to HBsAg of to be required for HBV clearance, and that this response was blocked by Treg cells. Inhibiting Treg cell activity using neutralizing antibody against CTLA4 restored the ability of Tfh cells to clear HBV infection; this approach

  9. THE ELECTRONIC STRUCTURE OF AG/CU(100) SURFACE ALLOYS STUDIES BY AUGER-PHOTOELECTRON COINCIDENCE SPECTROSCOPY.

    Energy Technology Data Exchange (ETDEWEB)

    ARENA,D.A.; BARTYNSKI,R.A.; HULBERT,S.L.

    2001-10-08

    We have measured the Ag and Pd M{sub 5}VV Auger spectrum in coincidence with Ag and Pd 4d{sub 5/2} photoelectrons for the Ag/Cu(100) and Pd/Cu(100) systems, respectively, as a function of admetal coverage. These systems form surface alloys (i.e. random substitutional alloys in the first atomic layer) for impurity concentrations in the 0.1 monolayer range. For these systems, the centroid of the impurity 4d levels is expected to shift away from the Fermi level by {approx}1 eV [Ruban et al., Journal of Molecular Catalysis. A 115 (1997) 421], an effect that should be easily seen in coincidence core-valence-valence Auger spectra. We find that the impurity Auger spectra of both systems shift in a manner that is consistent with d-band moving away from EF. However, the shift for Pd is considerably smaller than expected, and a shift almost absent for Ag. The disagreement between theory and experiment is most likely caused by the neglect of lattice relaxations in the calculations.

  10. Localized surface plasmon behavior of Ag-Cu alloy nanoparticles stabilized by rice-starch and gelatin

    Directory of Open Access Journals (Sweden)

    Manish Kumar Singh

    2015-10-01

    Full Text Available The purpose of this communication was to understand localized surface plasmon behavior of a series of Ag-Cu alloy nanoparticles capped by rice-starch and gelatin. The structures of dried powders were investigated with the help of X-ray diffraction. The analysis revealed Ag-rich and Cu-rich phases with maximum solid solubility of Cu ∼9 atom per cent; 8 atom per cent and Ag ∼ 16 atom per cent; 14 atom per cent in rice-starch and gelatin capped samples respectively. Transmission electron microscope was used for knowing the particle size as well as to supplement FCC phase formations of Ag-rich and Cu-rich solid phases arrived at based on X-ray diffraction studies. The UV-Vis spectra of sols were examined for the formation and stability of alloy nanoparticles. The temporal evolution of LSPR curves gave us to assert that the sol is stable for more than two months. Small angle X-ray scattering in the sol state was extensively utilized to understand nature of suspensions in terms of fractals. Such a study is important for having a correlation between LSPR behaviors with those of nanoparticle dispersion in aqueous media. It is believed that this work will be a contribution to the emerging field of plasmonics that include applications in the area of photophysical processes and photochemical reactions.

  11. Localized surface plasmon behavior of Ag-Cu alloy nanoparticles stabilized by rice-starch and gelatin

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Manish Kumar; Mandal, R. K., E-mail: rkmandal.met@itbhu.ac.in [Department of Metallurgical Engineering, IIT (BHU), Varanasi and DST Unit on Nanoscience and Technology, BHU, Varanasi-221 005 (India); Manda, Premkumar; Singh, A. K. [DefenceMetallurgical Research Laboratory, KanchanBagh, Hyderabad-500058 (India)

    2015-10-15

    The purpose of this communication was to understand localized surface plasmon behavior of a series of Ag-Cu alloy nanoparticles capped by rice-starch and gelatin. The structures of dried powders were investigated with the help of X-ray diffraction. The analysis revealed Ag-rich and Cu-rich phases with maximum solid solubility of Cu ∼9 atom per cent; 8 atom per cent and Ag ∼ 16 atom per cent; 14 atom per cent in rice-starch and gelatin capped samples respectively. Transmission electron microscope was used for knowing the particle size as well as to supplement FCC phase formations of Ag-rich and Cu-rich solid phases arrived at based on X-ray diffraction studies. The UV-Vis spectra of sols were examined for the formation and stability of alloy nanoparticles. The temporal evolution of LSPR curves gave us to assert that the sol is stable for more than two months. Small angle X-ray scattering in the sol state was extensively utilized to understand nature of suspensions in terms of fractals. Such a study is important for having a correlation between LSPR behaviors with those of nanoparticle dispersion in aqueous media. It is believed that this work will be a contribution to the emerging field of plasmonics that include applications in the area of photophysical processes and photochemical reactions.

  12. Stable structures and potential energy surface of the metallic clusters: Ni, Cu, Ag, Au, Pd, and Pt

    Science.gov (United States)

    Wu, Xia; Sun, Yan

    2017-06-01

    Metallic clusters have been widely studied due to their special electrical, optical, and catalytic properties. The many-body Gupta potential is applied to describe the interatomic interaction of Ni, Cu, Ag, Au, Pd, and Pt clusters, and their global minimal structures within 100 atoms are optimized using dynamic lattice searching (DLS) method. The configurational distribution of global minima is analyzed, and the geometrical difference among these clusters is demonstrated. Results show that the dominant motif of Ni and Cu clusters is the icosahedron, and in Ag and Au clusters the number of decahedra is slightly larger than that of the icosahedra. However, more face-centered cubic (fcc), stacking fault fcc, and amorphous structures are formed in Au clusters than in Ag clusters. Furthermore, the main motif of Pd and Pt clusters is the decahedron. In particular, Ni98 adopts a Leary tetrahedral motif, and Pt54 is a central vacant icosahedron. The difference related to the potential parameters of these metallic clusters is further investigated by energy analysis. Moreover, the potential energy surfaces (PES) of 38-atom metallic clusters is characterized in terms of conformational analysis. It was found that the sequence of the number of local minima on the PES from large to low is Ni, Cu, Ag, Pt, Pd, and Au.

  13. Direct Cross-Linking of Au/Ag Alloy Nanoparticles into Monolithic Aerogels for Application in Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Gao, Xiaonan; Esteves, Richard J Alan; Nahar, Lamia; Nowaczyk, Jordan; Arachchige, Indika U

    2016-05-25

    The direct cross-linking of Au/Ag alloy nanoparticles (NPs) into high surface area, mesoporous Au/Ag aerogels via chemical oxidation of the surface ligands is reported. The precursor alloy NPs with composition-tunable morphologies were produced by galvanic replacement of the preformed Ag hollow NPs. The effect of Au:Ag molar ratio on the NP morphology and surface plasmon resonance has been thoroughly investigated and resulted in smaller Au/Ag alloy NPs (4-8 nm), larger Au/Ag alloy hollow NPs (40-45 nm), and Au/Ag alloy hollow particles decorated with smaller Au NPs (2-5 nm). The oxidative removal of surfactant ligands, followed by supercritical drying, is utilized to construct large (centimeter to millimeter) self-supported Au/Ag alloy aerogels. The resultant assemblies exhibit high surface areas (67-73 m(2)/g), extremely low densities (0.051-0.055 g/cm(3)), and interconnected mesoporous (2-50 nm) networks, making them of great interest for a number of new technologies. The influence of mesoporous gel morphology on surface-enhanced Raman scattering (SERS) has been studied using Rhodamine 101 (Rd 101) as the probe molecule. The alloy aerogels exhibit SERS signal intensities that are 10-42 times higher than those achieved from the precursor Au/Ag alloy NPs. The Au/Ag alloy aerogel III exhibits SERS sensing capability down to 1 nM level. The increased signal intensities attained for alloy aerogels are attributed to highly porous gel morphology and enhanced surface roughness that can potentially generate a large number of plasmonic hot spots, creating efficient SERS substrates for future applications.

  14. Silica-covered star-shaped Au-Ag nanoparticles as new electromagnetic nanoresonators for Raman characterisation of surfaces

    Science.gov (United States)

    Krajczewski, Jan; Kołątaj, Karol; Pietrasik, Sylwia; Kudelski, Andrzej

    2018-03-01

    One of the tools used for determining the composition of surfaces of various materials is shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). SHINERS is a modification of "standard" surface-enhanced Raman spectroscopy (SERS), in which, before Raman spectra are recorded, the surfaces analysed are covered with a layer of plasmonic nanoparticles protected by a very thin layer of a transparent dielectric. The plasmonic cores of the core-shell nanoparticles used in SHINERS measurements generate a local enhancement of the electric field of the incident electromagnetic radiation, whereas the transparent coatings prevent the metal cores from coming into direct contact with the material being analysed. In this contribution, we propose a new type of SHINERS nanoresonators that contain spiky, star-shaped metal cores (produced from a gold/silver alloy). These spiky, star-shaped Au-Ag nanoparticles have been covered by a layer of silica. The small radii of the ends of the tips of the spikes of these plasmonic nanostructures make it possible to generate a very large enhancement of the electromagnetic field there, with the result that such SHINERS nanoresonators are significantly more efficient than the standard semi-spherical nanostructures. The Au-Ag alloy nanoparticles were synthesised by the reduction of a solution containing silver nitrate and chloroauric acid by ascorbic acid. The final geometry of the nanostructures thus formed was controlled by changing the ratio between the concentrations of AuCl4- and Ag+ ions. The shape of the synthesised star-shaped Au-Ag nanoparticles does not change significantly during the two standard procedures for depositing a layer of silica (by the decomposition of sodium silicate or the decomposition of tetraethyl orthosilicate).

  15. Frequency of infection by hepatitis B virus and its surface mutants in a northern Indian population.

    Science.gov (United States)

    Singh, Harjeet; Aggarwal, Rakesh; Singh, R L; Naik, S R; Naik, Sita

    2003-01-01

    The reported prevalence of hepatitis B virus (HBV) infection in the Indian general population varies from 2% to 11%. Epidemiological studies conducted so far have selection biases, since these included populations of defined age group, gender, social class, high-risk group, etc. The present study was designed to look for the molecular epidemiology of HBV infection in the rural and urban general populations in India. Sera obtained from healthy volunteers during college and social service camps from parts of northern India were tested for HBsAg and anti-HBc using enzyme immunoassays and for HBV DNA using polymerase chain reaction and Southern blot hybridization. The amplification products were cloned and sequenced, and nucleotide and deduced amino acid sequences of the surface and polymerase genes were analyzed for mutations. Of the 730 subjects (rural 543, urban 187), 15 (2.1%) tested positive for HBsAg and 143 (19.5%) for anti-HBc; 10 were positive for both. The overall HBV exposure rate in the population was 20.3% (148/730). The HBsAg carrier rate was similar in the urban and rural populations (1.5% and 2.3%; p=ns), and anti-HBc positivity was lower in the urban population (8.5% vs. 23.3%; ptransfusion was associated with markers of exposure to HBV (10.2% vs. 4.6%; p=0.01). Among the 220 representative samples tested for HBV DNA, 14 (6.4%) were positive; of these, only four were positive for HBsAg or anti-HBc. Sequencing of a 388-nt segment of the S-gene from three individuals (two adw and one ayw subtype) revealed four mutations. Two and three of these led to amino acid changes in the HBV surface and polymerase genes, respectively; alterations in known cytotoxic T cell epitopes of HBV surface and polymerase proteins were observed in one individual each. None had the G587A mutation, which is known to be associated with loss of the 'a' determinant of HBsAg. Our study shows a high frequency of exposure to HBV infection in the Indian general population; a proportion

  16. Quantum tunneling in real space: Tautomerization of single porphycene molecules on the (111) surface of Cu, Ag, and Au

    Science.gov (United States)

    Kumagai, Takashi; Ladenthin, Janina N.; Litman, Yair; Rossi, Mariana; Grill, Leonhard; Gawinkowski, Sylwester; Waluk, Jacek; Persson, Mats

    2018-03-01

    Tautomerization in single porphycene molecules is investigated on Cu(111), Ag(111), and Au(111) surfaces by a combination of low-temperature scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. It is revealed that the trans configuration is the thermodynamically stable form of porphycene on Cu(111) and Ag(111), whereas the cis configuration occurs as a meta-stable form. The trans → cis or cis → trans conversion on Cu(111) can be induced in an unidirectional fashion by injecting tunneling electrons from the STM tip or heating the surface, respectively. We find that the cis ↔ cis tautomerization on Cu(111) occurs spontaneously via tunneling, verified by the negligible temperature dependence of the tautomerization rate below ˜23 K. Van der Waals corrected DFT calculations are used to characterize the adsorption structures of porphycene and to map the potential energy surface of the tautomerization on Cu(111). The calculated barriers are too high to be thermally overcome at cryogenic temperatures used in the experiment and zero-point energy corrections do not change this picture, leaving tunneling as the most likely mechanism. On Ag(111), the reversible trans ↔ cis conversion occurs spontaneously at 5 K and the cis ↔ cis tautomerization rate is much higher than on Cu(111), indicating a significantly smaller tautomerization barrier on Ag(111) due to the weaker interaction between porphycene and the surface compared to Cu(111). Additionally, the STM experiments and DFT calculations reveal that tautomerization on Cu(111) and Ag(111) occurs with migration of porphycene along the surface; thus, the translational motion couples with the tautomerization coordinate. On the other hand, the trans and cis configurations are not discernible in the STM image and no tautomerization is observed for porphycene on Au(111). The weak interaction of porphycene with Au(111) is closest to the gas-phase limit and therefore the absence

  17. The interplay between surface-water and hydrogen bonding in a water adlayer on Pt(111) and Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Delle Site, Luigi [Max-Planck-Institut fuer Polymerforschung, Ackermannweg 10, D-55128 Mainz (Germany); Ghiringhelli, Luca M [Max-Planck-Institut fuer Polymerforschung, Ackermannweg 10, D-55128 Mainz (Germany); Andreussi, Oliviero [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56100 Pisa (Italy); Donadio, Davide [Computational Science, Department of Chemistry and Applied Biosciences, ETH Zurich, USI-Campus, via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Parrinello, Michele [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56100 Pisa (Italy)

    2007-06-20

    The structure of a water adlayer on a Pt(111) surface is investigated by means of extensive first-principles calculations. Allowing for proton disorder, the ground state energy for the {radical}3 x {radical}3R30{sup o} structure can be found. This results from an interplay between water/metal chemical bonding and the hydrogen bonding of the water network. This picture is supported by substituting Pt(111) with Ag(111): the almost inert surface allows for the reconstruction of the hydrogen network. (fast track communication)

  18. The interplay between surface-water and hydrogen bonding in a water adlayer on Pt(111) and Ag(111)

    International Nuclear Information System (INIS)

    Delle Site, Luigi; Ghiringhelli, Luca M; Andreussi, Oliviero; Donadio, Davide; Parrinello, Michele

    2007-01-01

    The structure of a water adlayer on a Pt(111) surface is investigated by means of extensive first-principles calculations. Allowing for proton disorder, the ground state energy for the √3 x √3R30 o structure can be found. This results from an interplay between water/metal chemical bonding and the hydrogen bonding of the water network. This picture is supported by substituting Pt(111) with Ag(111): the almost inert surface allows for the reconstruction of the hydrogen network. (fast track communication)

  19. Evidence for a gold trimer on the Si(111)-√{ 21} ×√{ 21}-(Ag + Au) surface

    Science.gov (United States)

    Takahashi, Toshio; Yamaguchi, Yudai; Shirasawa, Tetsuroh; Voegeli, Wolfgang; Tajiri, Hiroo

    2018-02-01

    The structure of the Si(111)-√{ 21} ×√{ 21}-(Ag + Au) surface is studied using surface X-ray diffraction and fluorescence yield measurements. The fluorescence measurements indicate that there are three gold atoms in the unit cell. From the analysis of the diffraction data, it is shown that the gold atoms form a trimer with an interatomic distance of 2.8 Å and that the sides of the trimer are almost parallel to the Si(111)-1 × 1 fundamental vectors, similar to that in the Si(111)-√{ 3} ×√{ 3}-Au structure.

  20. Impact of HBV genotype and mutations on HBV DNA and qHBsAg levels in patients with HBeAg-negative chronic HBV infection.

    Science.gov (United States)

    Kuhnhenn, L; Jiang, B; Kubesch, A; Vermehren, J; Knop, V; Susser, S; Dietz, J; Carra, G; Finkelmeier, F; Grammatikos, G; Zeuzem, S; Sarrazin, C; Hildt, E; Peiffer, K-H

    2018-04-10

    HBV DNA and quantitative (q)HBsAg levels as prognostic markers for HBV-related disease are mostly validated in Asia and their significance in Western populations is uncertain. To analyse the impact of the HBV genotype and frequent mutations in precore (PC), basal core promoter (BCP) and preS on HBV DNA and qHBsAg levels. HBV DNA and qHBsAg serum levels of 465 patients with HBeAg-negative chronic HBV infection were correlated with the HBV genotype and mutations in PC, BCP and preS. For a detailed analysis of the molecular virology, genotype A2 genomes harbouring these mutations were analysed for replication efficacy and HBsAg release in cell culture. While no impact of the HBV genotype on HBV DNA levels was observed, qHBsAg levels differed up to 1.4 log among the genotypes (P HBV DNA levels (P HBV genome harbouring a preS deletion. In contrast, a perinuclear HBsAg accumulation was detected for the PC and BCP-variants, reflecting an impaired HBsAg release. qHBsAg serum levels depend on the HBV genotype and together with HBV DNA levels on frequent mutations in PC, BCP and preS in HBeAg-negative patients. qHBsAg cut-offs when used as prognostic markers require genotype-dependent validation. © 2018 John Wiley & Sons Ltd.

  1. Facile preparation of dendritic Ag-Pd bimetallic nanostructures on the surface of Cu foil for application as a SERS-substrate

    Science.gov (United States)

    Yi, Zao; Tan, Xiulan; Niu, Gao; Xu, Xibin; Li, Xibo; Ye, Xin; Luo, Jiangshan; Luo, Binchi; Wu, Weidong; Tang, Yongjian; Yi, Yougen

    2012-05-01

    Dendritic Ag-Pd bimetallic nanostructures have been synthesized on the surface of Cu foil via a multi-stage galvanic replacement reaction (MGRR) of Ag dendrites in a Na2PdCl4 solution. After five stages of replacement reaction, one obtained structures with protruding Ag-Pd flakes; these will mature into many porous structures with a few Ag atoms that are left over dendrites. The dendritic Ag-Pd bimetallic nanostructures were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS). The morphology of the products strongly depended on the stage of galvanic replacement reaction and reaction temperature. The morphology and composition-dependent surface-enhanced Raman scattering (SERS) of the as-synthesized Ag-Pd bimetallic nanostructures were investigated. The effectiveness of these dendritic Ag-Pd bimetallic nanostructures on the surface of Cu foil as substrates toward SERS detection was evaluated by using rhodamine 6G (R6G) as a probe molecule. The results indicate that as-synthesized dendritic Ag-Pd bimetallic nanostructures are good candidates for SERS spectroscopy.

  2. Silver segregation in Ag/a-C nanocomposite coatings for potential application as antibacterial surfaces

    Science.gov (United States)

    Manninen, Noora Kristiina Alves de Sousa

    O desenvolvimento de superficies antibacterianas representa um desafio atual em diferentes aplicacoes industriais, nomeadamente, dispositivos medicos, embalagens alimentares, texteis e sistemas de tratamento de agua. A maioria das bacterias existe em biofilmes que aderem fortemente a diferentes tipos de superficies uma vez que esta adesao representa um mecanismo estrategico de sobrevivencia. O fenomeno da adesao e colonizacao microbiana resulta na falha de diferentes dispositivos e componentes utilizados nas aplicacoes acima mencionadas, tendo como consequencia perdas economicas elevadas e representando tambem um problema de saude publica quando se tratam de aplicacoes como dispositivos medicos ou embalagens alimentares. Neste sentido, ao longo das ultimas decadas o desenvolvimento de superficies antibacterianas tem sido considerada uma estrategia emergente no desenvolvimento de materiais mais eficientes a serem aplicados em diferentes sectores. O objetivo da presente tese consiste no desenvolvimento e caracterizacao de revestimentos nanocompositos multifuncionais baseados em revestimentos de carbono amorfo dopado com nanoparticulas de prata (Ag/a-C) para potencial aplicacao em superficies antibacterianas. A Ag e atualmente considerada como o agente bactericida mais promissor e eficiente, sendo que as nanoparticulas de prata representam o material mais comercializado na area da nanotecnologia. A estrategia de modificacao superficial com revestimentos baseados em carbono amorfo (a-C) tem-se tornado popular do ponto de vista industrial essencialmente, devido entre outras propriedades, a sua resistencia ao desgaste tribologico excecional, que permite combinar uma elevada dureza com um baixo coeficiente de atrito, elevada estabilidade quimica, resistencia a corrosao e biocompatibilidade em diferentes aplicacoes biomedicas. Na atualidade os revestimentos de a-C sao utilizados em diferentes aplicacoes industriais nomeadamente dispositivos medicos, laminas de barbear e

  3. Influence of growth temperature on formation of continuous Ag thin film on ZnO surface by ultra-high vacuum deposition

    International Nuclear Information System (INIS)

    Zhang, T C; Mei, Z X; Guo, Y; Xue, Q K; Du, X L

    2009-01-01

    Growth of an Ag film on a ZnO (0 0 0 1) surface by ultra-high vacuum deposition has been investigated by field emission scanning electron microscopy. It is revealed that the growth temperature has a considerable effect on the formation of a continuous Ag thin film on a ZnO surface. At room temperature or above, the formation of continuous Ag films with small thickness was found to be difficult due to an upstepping mechanism, whereas a continuous Ag film as thin as 30 nm was achieved at 140 K, resulting from the reduced migration length of silver atoms and the increased saturated island density at low temperature. Coalescence between the islands occurred and predominated over upstepping during subsequent deposition, which is favourable for the formation of a continuous Ag film with a smaller thickness.

  4. The intracellular HBV DNAs as novel and sensitive biomarkers for the clinical diagnosis of occult HBV infection in HBeAg negative hepatocellular carcinoma in China.

    Directory of Open Access Journals (Sweden)

    Hui Wang

    Full Text Available This study aimed to investigate the virological status in liver (both tumor and adjacent non-tumor tissue, the clinical features and the contribution of occult HBV infection (OBI to postoperative prognosis in HBeAg-negative(- hepatocellular carcinoma (HCC patients in China. Using quantitative TaqMan fluorescent real-time PCR assays, HBV covalently closed circular DNA (cccDNA and total DNA (tDNA were both quantified in 11 (HBsAg(- and 57 (HBsAg-positive(+ pairs of tumor tissue (TT and adjacent non-tumor tissue (ANTT obtained from HBeAg(- HCC patients who received no antiviral treatment and were negative for anti-HCV before surgical treatment. Of 11 HBsAg(- patients, 36% were with HBsAb(+ HBeAb(+ HBcAb(+. However, only 9% of the HBsAg(- patients were HBsAb(- HBeAb(+ HBcAb(+, which accounted for the majority (93% in the HBsAg(+ group. TT and ANTT HBV tDNAs in 11 HCC patients with HBsAg (- and HBeAg (- were all detectable. HBV cccDNA and tDNA were all lower in the HBsAg(- group than those in the HBsAg(+ group. By Kaplan-Meier analysis, patients with OBI were associated with a lower risk of cirrhosis and better overall survival (OS. The intracellular HBV DNAs, such as HBV cccDNA and tDNA are valuable biological markers for the diagnosis of occult HBV infection in HCC patients. This would assist the clinical implementation of a more personalized therapy for viral re-activation control and improve the survival rate of OBI patients.

  5. Excellent surface-enhanced Raman scattering (SERS) based on AgFeO2 semiconductor nanoparticles

    Science.gov (United States)

    Shi, Zhijie; Wang, Tao; Lin, Haiyang; Wang, Xiuhua; Ding, Juanjuan; Shao, Mingwang

    2013-09-01

    A simple hydrothermal method was employed to synthesize AgFeO2 nanoparticles, which were utilized as substrates in SERS detection of Rhodamine 6G and 4-mercaptobenzoic acid. The magnetic properties of the products provided the capability of concentrating analyte molecules under an external magnetic field. The detection in aqueous solution has ensured the uniformity of the SERS signals and the reproducibility of the substrates. It was interesting that the substrates exhibited high SERS activity at Rhodamine 6G concentration of 1 × 10-7 M with an enhancement factor of 5.1 × 105, showing the highest SERS effect for semiconductor substrates, which might be ascribed to the orderly orientation of AgFeO2 nanoparticles under external magnetic field.A simple hydrothermal method was employed to synthesize AgFeO2 nanoparticles, which were utilized as substrates in SERS detection of Rhodamine 6G and 4-mercaptobenzoic acid. The magnetic properties of the products provided the capability of concentrating analyte molecules under an external magnetic field. The detection in aqueous solution has ensured the uniformity of the SERS signals and the reproducibility of the substrates. It was interesting that the substrates exhibited high SERS activity at Rhodamine 6G concentration of 1 × 10-7 M with an enhancement factor of 5.1 × 105, showing the highest SERS effect for semiconductor substrates, which might be ascribed to the orderly orientation of AgFeO2 nanoparticles under external magnetic field. Electronic supplementary information (ESI) available: UV-vis absorption, magnetic hysteresis loop and thermogravimetric analysis of AgFeO2, Raman spectra of 0.01 M R6G solution and 4-mercaptobenzoic acid powder. See DOI: 10.1039/c3nr03460g

  6. The effect of Ni pre-implantation on surface morphology and optical absorption properties of Ag nanoparticles embedded in SiO2

    International Nuclear Information System (INIS)

    Shen, Yanyan; Qi, Ting; Qiao, Yu; Yu, Shengwang; Hei, Hongjun; He, Zhiyong

    2016-01-01

    Graphical abstract: - Highlights: • Ag concentration increased significantly due to the Ni pre-implantation. • Deposition and accumulation process of Ag atoms depends on Ni fluences. • The incorporation of Ni elements in Ag NPs can damp SPR absorption intensity. • AgNi alloy NPs embedded in SiO 2 have been created by sequentially implantation. • Unique SPR absorption with dual peaks centered at 406 nm and 563 nm was observed. - Abstract: The effect of Ni ion fluence on Ag nucleation and particle growth was investigated by sequentially implantation of 60 keV Ni ions at fluences of 1 × 10 16 , 5 × 10 16 , 1 × 10 17 ions/cm 2 and 70 keV Ag ions at a fluence of 5 × 10 16 ions/cm 2 . Due to the modification of the deposition and accumulation process of Ag implants caused by Ni pre-implantation, the surface morphology, structures, and optical absorption properties of the Ag nanoparticles (NPs) depends strongly on the Ni fluences. UV–vis absorption spectroscopy study showed that the introducing of Ni atoms lead to intensity decrease in the Ag SPR band. Remarkable local concentration increase of Ag profiles appeared for the sample pre-implanted by Ni ions of 5.0 × 10 16 ions/cm 2 . In particular, the AgNi alloy NPs with dual absorption peaks centered at 406 nm and 563 nm have been formed after 600 °C annealing in Ar atmosphere. However, at a low fluence of 1.0 × 10 16 ions/cm 2 , only small increase of the local Ag concentration than the Ag ions singly implanted sample can be observed. At a high fluence of 1.0 × 10 17 ions/cm 2 , lots Ag atoms are trapped close to the surface, which result in heavy sputtering loss of Ag atoms and the sublimation of Ag atoms after 600 °C annealing.

  7. Efficiency enhancement of fluorescence blue organic light-emitting diodes by incorporating Ag nanoparticles layers due to a localized surface plasmon

    Science.gov (United States)

    Nam, Minwoo; Chung, Nak-Kwan; Shim, Seob; Yun, Ju-Young; Kim, Jin-Tae; Pyo, Sung Gyu

    2017-09-01

    Enhanced electroluminescence in blue organic light-emitting diodes (OLEDs) is obtained by incorporating Ag nanoparticles (NPs) into hole injection layer of poly(3,4- ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS). The absorption peak of the localized surface plasmons (LSPs) introduced by the 60 nm Ag NPs matches the emission wavelength of the blue OLEDs were matched at wavelength of 442 nm. In addition, to maximize their coupling and to prevent the quenching of the emission, the distance between surface plasmons (SPs) around NPs and organic fluorophores is optimized. Finally, the emission intensity and the current efficiency of diode with Ag NPs were increased by 19% and 18%, respectively.

  8. Focused-ion-beam-fabricated Au nanorods coupled with Ag nanoparticles used as surface-enhanced Raman scattering-active substrate for analyzing trace melamine constituents in solution

    International Nuclear Information System (INIS)

    Sivashanmugan, Kundan; Liao, Jiunn-Der; Liu, Bernard Haochih; Yao, Chih-Kai

    2013-01-01

    Graphical abstract: -- Highlights: •Well-ordered Au-nanorod array with a controlled tip ring diameter (Au N Rs d ) is made by focused ion beam. •Au N Rs d coupled with Ag nanoparticles (Ag NPs/Au N Rs d ) is competent to sense target molecules in a solution. •Ag NPs/Au N Rs d SERS active substrate can detect a single molecule of crystal violet. •Ag NPs/Au N Rs d as a SERS-active substrate can distinguish melamine contaminants at low concentrations (e.g., 10 −12 M). -- Abstract: A well-ordered Au-nanorod array with a controlled tip ring diameter (Au N Rs d ) was fabricated using the focused ion beam method. Au N Rs d was then coupled with Ag nanoparticles (Ag NPs) to bridge the gaps among Au nanorods. The effect of surface-enhanced Raman scattering (SERS) on Au N Rs d and Ag NPs/Au N Rs d was particularly verified using crystal violet (CV) as the molecular probe. Raman intensity obtained from a characteristic peak of CV on Au N Rs d was estimated by an enhancement factor of ≈10 7 in magnitude, which increased ≈10 12 in magnitude for that on Ag NPs/Au N Rs d . A highly SERS-active Ag NPs/Au N Rs d was furthermore applied for the detection of melamine (MEL) at very low concentrations. Raman-active peaks of MEL (10 −3 to 10 −12 M) in water or milk solution upon Au N Rs d or Ag NPs/Au N Rs d were well distinguished. The peaks at 680 and 702 cm −1 for MEL molecules were found suitable to be used as the index for sensing low-concentration MEL in a varied solution, while that at 1051 cm −1 was practical to interpret MEL molecules in water or milk solution bonded with Au (i.e., Au N Rs d ) or Ag (i.e., Ag NPs/Au N Rs d ) surface. At the interface of Ag NPs/Au N Rs d and MEL molecules in milk solution, a laser-induced electromagnetic field or hotspot effect was produced and competent to sense low-concentration MEL molecules interacting with Ag and Au surfaces. Accordingly, Ag NPs/Au N Rs d is very promising to be used as a fast and sensitive tool for

  9. Adsorption of cobalt (II) octaethylporphyrin and 2H-octaethylporphyrin on Ag(111): new insight into the surface coordinative bond

    International Nuclear Information System (INIS)

    Bai Yun; Buchner, Florian; Kellner, Ina; Schmid, Martin; Vollnhals, Florian; Steinrueck, Hans-Peter; Marbach, Hubertus; Michael Gottfried, J

    2009-01-01

    The adsorption of cobalt (II) octaethylporphyrin (CoOEP) and 2H-octaethylporphyrin (2HOEP) on Ag(111) was investigated with scanning tunneling microscopy (STM) and photoelectron spectroscopy (XPS/UPS), in order to achieve a detailed mechanistic understanding of the surface chemical bond of coordinated metal ions. Previous studies of related systems, especially cobalt (II) tetraphenylporphyrin (CoTPP) on Ag(111), have revealed adsorption-induced changes of the oxidation state of the Co ion and the appearance of a new valence state. These effects were attributed to a covalent interaction of the Co ion with the silver substrate. However, recent studies show that the porphyrin ligand of adsorbed CoTPP undergoes a pronounced saddle-shape distortion, which could alter the electronic structure and thus provide an alternative explanation for the new valence state previously attributed to the formation of a surface coordinative bond. With the octaethylporphyrins investigated here, which were found to adsorb in a flat, undistorted conformation on Ag(111), the effects of geometric distortion can be separated from those of the electronic interaction with the substrate. The CoOEP monolayer gives rise to an adsorption-induced shift of the Co 2p signal (-1.9 eV relative to the multilayer), a new valence state at 0.6 eV below the Fermi energy, and a work-function shift of -0.84 eV (2HOEP: -0.44 eV) relative to the clean surface. Comparison with data for the distorted CoTPP confirms the existence of a covalent ion-surface interaction that is insensitive to the conformation of the ligand.

  10. Baseline hepatitis B surface antigen quantitation can predict virologic response in entecavir-treated chronic hepatitis B patients.

    Science.gov (United States)

    Wang, Chia-Chi; Tseng, Tai-Chung; Wang, Pin-Chao; Lin, Hans Hsienhong; Kao, Jia-Horng

    2014-11-01

    Several anti-viral drugs are approved for the treatment of hepatitis B virus (HBV) infection. However, whether quantitative hepatitis B surface antigen (qHBsAg) can predict the therapeutic response during long-term entecavir treatment remains unclear. Fifty-five chronic hepatitis B (CHB) patients who received entecavir for more than 2 years were enrolled. The serum qHBsAg level was measured by HBsAg II quant immunoassay. A significant decline in the qHBsAg level was defined as > 1 log reduction from baseline to 6 months of entecavir treatment. Of the 55 patients (41 males and 14 females with a mean age of 48.3 ± 11.4 years), 23 patients were positive for hepatitis B e antigen (HBeAg). The median treatment period was 34 months, and ranged from 26 months to 43 months. A total of 288 serum samples were used to determine the qHBsAg levels. At year 3 of entecavir therapy, one (1.8%) patient had HBsAg seroclearance. A high qHBsAg level was defined as greater than 10,000 IU/mL. Patients with a high baseline qHBsAg level had a lower rate of virologic response at year 1 (37.5% vs. 89.7%, p response in all patients. The baseline serum qHBsAg level can predict virologic response in entecavir-treated CHB patients. However, a significant decline in the qHBsAg level cannot predict serologic or virologic response of entecavir treatment. Copyright © 2013. Published by Elsevier B.V.

  11. Nanospherical-lens lithographical Ag nanodisk arrays embedded in p-GaN for localized surface plasmon-enhanced blue light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Tongbo, E-mail: tbwei@semi.ac.cn; Wu, Kui; Sun, Bo; Zhang, Yonghui; Chen, Yu; Huo, Ziqiang; Hu, Qiang; Wang, Junxi; Zeng, Yiping; Li, Jinmin [State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 (China); Lan, Ding [National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100080 (China)

    2014-06-15

    Large-scale Ag nanodisks (NDs) arrays fabricated using nanospherical-lens lithography (NLL) are embedded in p-GaN layer of an InGaN/GaN light-emitting diode (LED) for generating localized surface plasmon (LSP) coupling with the radiating dipoles in the quantum-well (QWs). Based on the Ag NDs with the controlled surface coverage, LSP leads to the improved crystalline quality of regrowth p-GaN, increased photoluminescence (PL) intensity, reduced PL decay time, and enhanced output power of LED. Compared with the LED without Ag NDs, the optical output power at a current of 350 mA of the LSP-enhanced LEDs with Ag NDs having a distance of 20 and 35 nm to QWs is increased by 26.7% and 31.1%, respectively. The electrical characteristics and optical properties of LEDs with embedded Ag NPs are dependent on the distance of between Ag NPs and QWs region. The LED with Ag NDs array structure is also found to exhibit reduced emission divergence, compared to that without Ag NDs.

  12. Impact of the thimerosal controversy on hepatitis B vaccine coverage of infants born to women of unknown hepatitis B surface antigen status in Michigan.

    Science.gov (United States)

    Biroscak, Brian J; Fiore, Anthony E; Fasano, Nancy; Fineis, Patrick; Collins, Michael P; Stoltman, Gillian

    2003-06-01

    Hepatitis B vaccine is recommended for all infants, and the series may be started during the delivery admission. For infants who are born either to women who are positive for hepatitis B surface antigen (HBsAg) or to women whose HBsAg status is unknown, vaccination should be started within 12 hours of birth to prevent perinatal and early childhood hepatitis B virus infection. Because of concerns about mercury exposures from vaccines that contain thimerosal, the United States Public Health Service (USPHS) and the American Academy of Pediatrics (AAP) recommended in July 1999 that the first dose of hepatitis B vaccine be deferred until 2-6 months of age but only for infants who are born to HBsAg-negative women. To assess the impact on birth-dose vaccine coverage for infants who are born to women with unknown HBsAg status, we measured coverage before and after July 1999. A sample of Michigan infants who were born to women whose HBsAg status was either unknown or missing were identified by reviewing newborn screening cards for infants who were born during 1) March-April 1999 (before recommendation changes [T1]); 2) July 15-September 15, 1999 (immediately after recommendation changes [T2]); and 3) March-April 2000 (6 months after resumption of pre-1999 practices were recommended [T3]). We verified maternal HBsAg screening and newborn hepatitis B vaccination by reviewing infant and maternal hospital records. Of 1201 infants who were born to women whose HBsAg status was indicated as unknown or missing on the newborn screening card during the 3 time periods, 216 (18%) were born to women whose status was truly unknown at the time of delivery, as determined by medical record review. During T1, 53% of these 216 infants received hepatitis B vaccine before hospital discharge, compared with 7% of infants who were born during T2 and 57% of infants who were born during T3. During T1, 19% of these infants received hepatitis B vaccine within 12 hours of birth compared with 1% of

  13. [Rapid determination of melamine in pet food by surface enhanced Raman spectroscopy in combination with Ag nanoparticles].

    Science.gov (United States)

    Cheng, Jie; Su, Xiao-Ou

    2011-01-01

    The rapid qualitative and quantitative analysis of melamine in pet food was realized by surface-enhanced Raman spectroscopy in combination with Ag nanoparticle. In the present study, the 709 and 1 542 cm(-1) Raman shift was chosen as qualitative basis. The quantitative calculation of the concentration range between 1.0 and 10.0 mg x kg(-1) was achieved based on the intensity of 1 149 cm(-1) Raman peak which was used as a normalization standard. The limit of detection was 0.5 mg x kg(-1). The Ag nanoparticle had a strong Raman enhancement effect on melamine and the intensity was affected by the adding time of Ag nanoparticle and the vortex strength. At the same time, the intensity of SERS was affected by the extraction solvent type, and the manner of extraction. The analysis time of each sample was about 5 min. It was so quick that it was easy to realize the rapid detection of melamine in pet food compared with existing methods.

  14. Fast and eco-friendly fabrication of uniform Ag substrates for highly sensitive surface-enhanced Raman scattering

    Science.gov (United States)

    Xu, Yongda; Li, Xin; Jiang, Lan; Meng, Ge; Ran, Peng; Lu, Yongfeng

    2017-05-01

    This study proposed a fast, simple, eco-friendly method for obtaining highly sensitive and uniform surface-enhanced Raman scattering (SERS) of silver (Ag) nanotextured substrates decorated with silver nanoparticles in open air. By splitting conventional femtosecond pulses (subpulse delay Δt = 0 ps) into pulse trains (subpulse delay Δt = 3 ps), the mean diameter of Ag nanoparticles was reduced by almost half and the amount of Ag nanoparticles with a diameter ranging from 20 to 60 nm was increased by more than 11 times. The substrate fabricated by femtosecond pulse trains has four main merits as follows: (1) High sensitivity: the maximum SERS enhancement factor is 1.26 × 109; (2) High efficiency: the fabrication rate can be up to 1600 μm2/s, which is 20-40 times faster than femtosecond photochemical reduction; (3) Good reproducibility: the relative standard deviation of the Raman signal intensity is 10.7%, which is one-third of that for conventional femtosecond laser; (4) Eco-friendly fabrication: neither chemical reagents nor vacuum conditions are needed during the fabrication process.

  15. On Auger neutralization of He sup + ions on a Ag(111) surface

    CERN Document Server

    Monreal, R C; Esaulov, V A

    2003-01-01

    Neutralization of He sup + ions in grazing incidence scattering on Ag(111) is studied. A small scattered ion fraction is observed. The experimental results are discussed in terms of survival from Auger neutralization, whose rates are derived theoretically. Molecular dynamics simulations of scattered ion trajectories are performed and the surviving ion fractions are then calculated using the theoretically estimated Auger neutralization rates. The calculations agree quite well with the experimental data and empirical estimates of the neutralization rates.

  16. Generation of Localized Surface Plasmon Resonance Using Hybrid Au–Ag Nanoparticle Arrays as a Sensor of Polychlorinated Biphenyls Detection

    Directory of Open Access Journals (Sweden)

    Jing Liu

    2016-08-01

    Full Text Available In this study, the hybrid Au–Ag hexagonal lattice of triangular and square lattice of quadrate periodic nanoparticle arrays (PNAs were designed to investigate their extinction spectra of the localized surface plasmon resonances (LSPRs. First, their simulating extinction spectra were calculated by discrete dipole approximation (DDA numerical method by changing the media refractive index. Simulation results showed that as the media refractive index was changed from 1.0 to 1.2, the maximum peak intensity of LSPRs spectra had no apparent change and the wavelength to reveal the maximum peak intensity of LSPRs spectra was shifted lower value. Polystyrene (PS nanospheres with two differently arranged structures were used as the templates to deposit the hybrid Au–Ag hexagonal lattice of triangular and square lattice of quadrate periodic PNAs by evaporation method. The hybrid Au–Ag hexagonal lattice of triangular and square lattice of quadrate PNAs were grown on single crystal silicon (c-Si substrates, and their measured extinction spectra were compared with the calculated results. Finally, the fabricated hexagonal lattices of triangular PNAs were investigated as a sensor of polychlorinated biphenyl solution (PCB-77 by observing the wavelength to reveal the maximum extinction efficiency (λmax. We show that the adhesion of β-cyclodextrins (SH-β-CD on the hybrid Au–Ag hexagonal lattice of triangular PNAs could be used to increase the variation of λmax. We also demonstrate that the adhesion of SH-β-CD increases the sensitivity and detection effect of PCB-77 in hexagonal lattice of triangular PNAs.

  17. Triple positivity of HBsAg, anti-HCV antibody, and HIV and their ...

    African Journals Online (AJOL)

    tested positive to HIV/HBV/HCV triple infection before and after the commencement of HAART. Of these infections, ... Testing of these triple infections should be a big concern in the best choice and commencement of ART. Also, the study showed that ..... Godsworth, N.J., Cooper, D.A. and Disnovan, B. (2009). The influence ...

  18. Self-assembled monolayers of bimetallic Au/Ag nanospheres with superior surface-enhanced Raman scattering activity for ultra-sensitive triphenylmethane dyes detection.

    Science.gov (United States)

    Tian, Yue; Zhang, Hua; Xu, Linlin; Chen, Ming; Chen, Feng

    2018-02-15

    The bimetallic Au/Ag self-assembled monolayers (SAMs) were constructed by using mono-dispersed Au/Ag nanospheres (Ag: 4.07%-34.53%) via evaporation-based assembly strategy. The composition-dependent surface-enhanced Raman scattering (SERS) spectroscopy revealed that the Au/Ag (Ag: 16.83%) SAMs provide maximized activity for triphenylmethane dyes detection. With the inter-metallic synergy, the optimized SAMs enable the Raman intensity of crystal violet molecules to be about 223 times higher than that of monometallic Au SAMs. Moreover, the SERS signals with excellent uniformity (<5% variation) are sensitive down to 10 -13   M concentrations because of the optimal matching between bimetallic plasmon resonance and the incident laser wavelength.

  19. Development and evaluation of an in-house ELISA to detect hepatitis B virus surface antigen in resource-limited settings.

    Science.gov (United States)

    Fatema, K; Tabassum, S; Nessa, A; Jahan, M

    2013-08-01

    Hepatitis B virus (HBV) infection is of global public health concern. Among various serological tests used for the diagnosis and screening of HBV infection, the enzyme-linked immunosorbent assay (ELISA) to detect hepatitis B surface antigen (HbsAg) is most widely used. The present study was designed to develop and standardize a cost effective in-house ELISA for the detection of HbsAg and compare its performance with two established commercial kits. The concentrations of coating antibody, conjugates and sera were fixed by checkerboard titration. Using known HBsAg positive and negative sera, four different concentrations (1, 0.5, 0.25 and 0.125 microg/well) of coating anti-HBs were applied. Similarly, serial dilutions of patients' sera (1 in 2, 1 in 3, 1 in 5 and 1 in 9) and conjugates (1 in 2, 1 in 3, 1 in 5, 1 in 9 and 1 in 17) were evaluated by checkerboard titration. The optimal concentration of coating antibody was determined at 0.25 microg/well and 1 in 9 dilution for both conjugates and sera. The performance comparison of our in-house ELISA showed excellent correlation with two commercial kits (Pearson 0.957, P = 0.001 for monoclonal antibody coated kit and Pearson 0.929, P = 0.000 for polyclonal antibody coated kit) when OD values were compared. All commercial kit proven positive samples was positive while all negative samples were negative with the in-house ELISA resulting in 100% sensitivity and specificity. The results of our study demonstrated that our in-house ELISA for detection of HBsAg was equally as sensitive and specific as two well-known commercial kits. Thus, this system may be a useful tool for diagnostic and screening purposes, as well as outbreak investigations.

  20. Improved humoral and cellular immune responses against the gp120 V3 loop of HIV-1 following genetic immunization with a chimeric DNA vaccine encoding the V3 inserted into the hepatitis B surface antigen

    DEFF Research Database (Denmark)

    Fomsgaard, A; Nielsen, H V; Bryder, K

    1998-01-01

    by gene gun was used for genetic immunization in a mouse model. Antibody and CTL responses to MN V3 and HBsAg were measured and compared with the immune responses obtained after vaccination with plasmids encoding the complete HIV-1 MN gp160 and HBsAg (pre-S2 + S), respectively. DNA vaccination...

  1. Fabrication of silver nanoparticles embedded into polyvinyl alcohol (Ag/PVA) composite nanofibrous films through electrospinning for antibacterial and surface-enhanced Raman scattering (SERS) activities.

    Science.gov (United States)

    Zhang, Zhijie; Wu, Yunping; Wang, Zhihua; Zou, Xueyan; Zhao, Yanbao; Sun, Lei

    2016-12-01

    Silver nanoparticle-embedded polyvinyl alcohol (PVA) nanofibers were prepared through electrospinning technique, using as antimicrobial agents and surface-enhanced Raman scattering (SERS) substrates. Ag nanoparticles (NPs) were synthesized in liquid phase, followed by evenly dispersing in PVA solution. After electrospinning of the mixed solution at room temperature, the PVA embedded with Ag NPs (Ag/PVA) composite nanofibers were obtained. The morphologies and structures of the as-synthesized Ag nanoparticles and Ag/PVA fibers were characterized by the techniques of transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Ag NPs have an average diameter of 13.8nm, were found to be uniformly dispersed in PVA nanofibers. The Ag/PVA nanofibers provided robust antibacterial activities against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) microorganisms. It's also found that Ag/PVA nanofibers make a significant contribution to the high sensitivity of SERS to 4-mercaptophenol (4-MPh) molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. A ternary functional Ag@GO@Au sandwiched hybrid as an ultrasensitive and stable surface enhanced Raman scattering platform

    Science.gov (United States)

    Zhang, Cong-yun; Hao, Rui; Zhao, Bin; Hao, Yao-wu; Liu, Ya-qing

    2017-07-01

    The graphene-mediated surface enhanced Raman scattering (SERS) substrates by virtues of plasmonic metal nanostructures and graphene or its derivatives have attracted tremendous interests which are expected to make up the deficiency of traditional plasmonic metal substrates. Herein, we designed and fabricated a novel ternary Ag@GO@Au sandwich hybrid wherein the ultrathin graphene oxide (GO) films were seamlessly wrapped around the hierarchical flower-like Ag particle core and meanwhile provided two-dimensional anchoring scaffold for the coating of Au nanoparticles (NPs). The surface coverage density of loading Au NPs could be readily controlled by tuning the dosage amount of Au particle solutions. These features endowed the sandwiched structures high enrichment capability for analytes such as aromatic molecules and astonishing SERS performance. The Raman signals were enormously enhanced with an ultrasensitive detection limit of rhodamine-6G (R6G) as low as 10-13 M based on the chemical enhancement from GO and multi-dimensional plasmonic coupling between the metal nanoparticles. In addition, the GO interlayer as an isolating shell could effectively prevent the metal-molecule direct interaction and suppress the oxidation of Ag after exposure at ambient condition which enabled the substrates excellent reproducibility with less than 6% signal variations and prolonged life-time. To evaluate the feasibility and the practical application for SERS detection in real-world samples based on GO sandwiched hybrid as SERS-active substrate, three different prohibited colorants with a series of concentrations were measured with a minimum detected concentration down to 10-9 M. Furthermore, the prepared GO sandwiched nanostructures can be used to identify different types of colorants existing in red wine, implying the great potential applications for single-particle SERS sensing of biotechnology and on-site monitoring in food security.

  3. Effect of Isothermal Aging on the Long-Term Reliability of Fine-Pitch Sn-Ag-Cu and Sn-Ag Solder Interconnects With and Without Board-Side Ni Surface Finish

    Science.gov (United States)

    Lee, Tae-Kyu; Duh, Jeng-Gong

    2014-11-01

    The combined effects on long-term reliability of isothermal aging and chemically balanced or unbalanced surface finish have been investigated for fine-pitch ball grid array packages with Sn-3.0Ag-0.5Cu (SAC305) (wt.%) and Sn-3.5Ag (SnAg) (wt.%) solder ball interconnects. Two different printed circuit board surface finishes were selected to compare the effects of chemically balanced and unbalanced structure interconnects with and without board-side Ni surface finish. NiAu/solder/Cu and NiAu/solder/NiAu interconnects were isothermally aged and thermally cycled to evaluate long-term thermal fatigue reliability. Weibull plots of the combined effects of each aging condition and each surface finish revealed lifetime for NiAu/SAC305/Cu was reduced by approximately 40% by aging at 150°C; less degradation was observed for NiAu/SAC305/NiAu. Further reduction of characteristic life-cycle number was observed for NiAu/SnAg/NiAu joints. Microstructure was studied, focusing on its evolution near the board and package-side interfaces. Different mechanisms of aging were apparent under the different joint configurations. Their effects on the fatigue life of solder joints are discussed.

  4. Modification of Ag nanoparticles on the surface of SrTiO3 particles and resultant influence on photoreduction of CO2

    Science.gov (United States)

    Shao, Kunjuan; Wang, Yanjie; Iqbal, Muzaffar; Lin, Lin; Wang, Kai; Zhang, Xuehua; He, Meng; He, Tao

    2018-03-01

    Modification of a wide-bandgap semiconductor with noble metals that can exhibit surface plasmon effect is an effective approach to make it responsive to the visible light. In this work, a series of cubic and all-edge-truncated SrTiO3 with and without thermal pretreatment in air are modified by Ag nanoparticles via photodeposition method. The crystal structure, morphology, loading amount of Ag nanoparticles, and optical properties of the obtained Ag-SrTiO3 nanomaterials are well characterized by powder X-ray diffraction, scanning microscope, transmission electron microscope, energy disperse X-ray spectroscopy, ICP-MS and UV-vis diffuse-reflection spectroscopy. The loading amount and size of the Ag nanoparticles can be controlled to some extent by tuning the photodeposition time via growth-dissolution mechanism. The Ag nanoparticles are inclined to deposit on different locations on the surface of cubic and truncated SrTiO3 with and without thermal pretreatment. The resultant SrTiO3 modified by Ag nanoparticles exhibits visible light activity for photocatalytic reduction of CO2, which is closely related to the oxygen vacancy induced by thermal pretreatment, size and amount of Ag nanoparticles. Accordingly, there is an optimized photodeposition time for the synthesis of the photocatalyst that exhibits the highest photocatalytic activity.

  5. Accumulation and interparticle connections of triangular Ag-coated Au nanoprisms by oil-coating method for surface-enhanced Raman scattering applications

    Science.gov (United States)

    Noda, Yuta; Asaka, Toru; Fudouzi, Hiroshi; Hayakawa, Tomokatsu

    2018-03-01

    To examine the optical responses of surface-enhanced Raman scattering (SERS) for tuned plasmonic nanoparticles, triangular Ag-coated Au (Au@Ag) nanoprisms with different sizes were separately synthesized, which were well controlled in their size (edge-length) and localized surface plasmon resonance (LSPR) wavelength (69.0 ± 8.4 to 173.8 ± 25.6 nm in size and 662-943 nm in LSPR wavelength). The mechanism of Ag shell formation on the Au nanoprisms was also studied with scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS). The Au@Ag nanoprisms were immobilized by covering a colloidal solution containing the nanoprisms with silicone oil and evaporating the solvent in the oil (oil-coating method) so as to form a layer of accumulated plasmonic Au@Ag nanoprisms that had LSPR peak wavelengths tuned from 839 to 1182 nm. The accumulation conditions were analyzed by field-emission scanning electron microscopy (FE-SEM) and a Raman mapping technique. The Au@Ag nanoprisms under excitation at 632.8 nm exhibited higher SERS signals of rhodamine 6G, and SERS-mapped images of the novel immobilized films were obtained at different magnifications. It was concluded that accumulated Au@Ag nanoprisms undergoing tip-planar interconnections could produce enhanced local fields, resulting in higher SERS signals.

  6. Novel transparent high-performance AgNWs/ZnO electrodes prepared on unconventional substrates with 3D structured surfaces

    Science.gov (United States)

    Lan, Wei; Yang, Zhiwei; Zhang, Yue; Wei, Yupeng; Wang, Pengxiang; Abas, Asim; Tang, Guomei; Zhang, Xuetao; Wang, Junya; Xie, Erqing

    2018-03-01

    With the development of optoelectronic devices with three-dimensional (3D) structured surfaces, transparent electrodes that can be deposited on non-plane substrates have become increasingly important. In this paper, novel transparent silver nanowire (AgNWs)/ZnO film electrodes were uniformly prepared on treated 3D glass and PET substrates with a combination of spin-coating and heat-welding. The AgNWs/ZnO films show a transmittance of ∼88% and a sheet resistance of ∼10 Ω/sq. They are comparable with commercial ITO films. Furthermore, only a small in-plane resistance variation of ∼1 Ω/sq was measured using four-point probe mapping in films with a 10 cm × 10 cm area. These results confirm that these novel film electrodes are very uniform. Both electrical resistance and optical transmittance of the films remain mostly intact after 1000 bending cycles and tape peeling-tests with 10 cycles. The films show high thermal stability for more than one month at 80 °C. The strategy provides a new route for the design and fabrication of optoelectronic devices with 3D structured surfaces.

  7. In situ surface-enhanced Raman spectroscopy effect in zeolite due to Ag2Se quantum dots

    International Nuclear Information System (INIS)

    Martinez-Nuñez, C. E.; Cortez-Valadez, M.; Delgado-Beleño, Y.; Flores-López, N. S.; Román-Zamorano, J. F.; Flores-Valenzuela, J.; Flores-Acosta, M.

    2017-01-01

    This study shows the presence of surface-enhanced Raman spectroscopy (SERS) effect caused by Ag 2 Se quantum dots embedded in the zeolite matrix. The quantum dots that were synthesised and stabilised in the matrix of F9-NaX zeolite show a size of 5 nm and a quasi-spherical morphology. The calculated interplanar distances confirm the presence of quantum dots in cubic phase Im-m. We suppose that the in situ SERS effect in the material is caused by chemical-enhancement mechanism (CEM). The density functional theory (DFT) is undertaken to corroborate our hypothesis. The structure H 8 Si 8 Al 8 O 12 represents the zeolite cavity unit, and small clusters of (Ag 2 Se) n represent the quantum dots. Both structures interact in the cavity to obtain the local minimum of the potential energy surface, leading to new molecular orbitals. After the analysis of the predicted Raman spectrum, the Raman bands increase significantly, agreeing with the experimental results at low wavenumbers in F9-NaX zeolite.

  8. In situ surface-enhanced Raman spectroscopy effect in zeolite due to Ag{sub 2}Se quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Nuñez, C. E. [Universidad de Sonora, Departamento de Investigación en Física (Mexico); Cortez-Valadez, M., E-mail: jose.cortez@unison.mx, E-mail: manuelcortez@live.com [Universidad de Sonora, CONACYT-Departamento de Investigación en Física (Mexico); Delgado-Beleño, Y.; Flores-López, N. S. [Universidad de Sonora, Departamento de Investigación en Física (Mexico); Román-Zamorano, J. F. [Centro de Investigación y Desarrollo Tecnológico en Electroquímica (Mexico); Flores-Valenzuela, J. [Universidad Autónoma de Sinaloa (Mexico); Flores-Acosta, M. [Universidad de Sonora, Departamento de Investigación en Física (Mexico)

    2017-02-15

    This study shows the presence of surface-enhanced Raman spectroscopy (SERS) effect caused by Ag{sub 2}Se quantum dots embedded in the zeolite matrix. The quantum dots that were synthesised and stabilised in the matrix of F9-NaX zeolite show a size of 5 nm and a quasi-spherical morphology. The calculated interplanar distances confirm the presence of quantum dots in cubic phase Im-m. We suppose that the in situ SERS effect in the material is caused by chemical-enhancement mechanism (CEM). The density functional theory (DFT) is undertaken to corroborate our hypothesis. The structure H{sub 8}Si{sub 8}Al{sub 8}O{sub 12} represents the zeolite cavity unit, and small clusters of (Ag{sub 2}Se){sub n} represent the quantum dots. Both structures interact in the cavity to obtain the local minimum of the potential energy surface, leading to new molecular orbitals. After the analysis of the predicted Raman spectrum, the Raman bands increase significantly, agreeing with the experimental results at low wavenumbers in F9-NaX zeolite.

  9. Reactivity of Surface Nitrates in H2-Assisted SCR of NOx Over Ag/Al2O3 Catalyst

    DEFF Research Database (Denmark)

    Sadokhina, N. A.; Doronkin, Dmitry E.; Baeva, G. N.

    2013-01-01

    The role of nitrate ad-species in H2-assisted SCR over Ag/Al2O3 was compared in NH3-SCR and n-C6H14-SCR processes. It was found that nitrates could be reduced by NH3 or n-C6H14 at similar rates with H2 co-feeding which indicates a common rate-limiting step. However, contributions of surface nitrate...... reduction to the overall NH3-SCR or n-C6H14-SCR are different as revealed by comparing the rates of nitrate reduction with the rates of steady-state processes. The rate of the steady-state n-C6H14-SCR is virtually identical to the rate of surface nitrate reduction suggesting a significant contribution...

  10. Evaluation of the highly sensitive chemiluminescent enzyme immunoassay "Lumipulse HBsAg-HQ" for hepatitis B virus screening.

    Science.gov (United States)

    Deguchi, Matsuo; Kagita, Masanori; Yoshioka, Nori; Tsukamoto, Hiroko; Takao, Miyuki; Tahara, Kazuko; Maeda, Ikuhiro; Hidaka, Yoh; Yamauchi, Satoshi; Kaneko, Atsushi; Miyakoshi, Hideo; Isomura, Mitsuo

    2017-10-06

    Ongoing efforts in the development of HBsAg detection kits are focused on improving sensitivity and specificity. The purpose of this study was to evaluate an improved, highly sensitive quantitative assay, "Lumipulse HBsAg-HQ", a chemiluminescent enzyme immunoassay designed for a fully automated instrument, the "Lumipulse G1200". Serum samples for reproducibility, dilution, correlation, sensitivity, and specificity studies were obtained from patients at the Osaka University Hospital. Seroconversion and sensitivity panels were purchased from a commercial vender. Subtype, sensitivity panels, and HBsAg recombinant proteins with one or two amino acid substitutions were prepared in-house. The coefficients of variation for the low, medium, and high concentration samples ranged from 1.93 to 2.55%. The HBsAg-HQ reagent for dilution testing showed good linearity in the 0.005-150 HBsAg IU/mL range and no prozone phenomenon. All 102 HBV carrier samples were positive by HBsAg-HQ, while other commercial reagents showed one or more to be negative. In the seroconversion panel, the 14-day blood sample was positive. The sensitivity against HBsAg-HQ "ad" and "ay" subtypes was 0.025 ng/mL. Comparisons among the HBsAg-HQ, HISCL, and Architect HBsAg reagents were performed using the Bland-Altman plot. Specificity for 1000 seronegative individuals was 99.7%. HBsAg-HQ detected 29 positive serum among 12 231 routinely obtained serum samples, which showed concentrations of 0.005-0.05 HBsAg IU/mL. According to these results, the Lumipulse HBsAg-HQ assay, with a highly sensitive limit of detection of 0.005 IU/mL, may facilitate the development of a better management strategy for a considerable proportion of infected patients. © 2017 Wiley Periodicals, Inc.

  11. Correlations of Optical Absorption, Charge Trapping, and Surface Roughness of TiO2 Photoanode Layer Loaded with Neat Ag-NPs for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Yang, Dongwook; Jang, Jae Gyu; Lim, Joohyun; Lee, Jin-Kyu; Kim, Sung Hyun; Hong, Jong-In

    2016-08-24

    We systematically investigated the effect of silver nanoparticles (Ag-NPs) on the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Neat, spherical Ag-NPs at loading levels of 0.0, 0.5, 1.0, and 2.0 wt % were embedded into the titanium dioxide (TiO2) photoanode layer. The plasmonic effect of the Ag-NPs strongly enhanced the incident light absorption over a wide range of the visible wavelength region in addition to the inherent absorbance of the perovskite sensitizer. The low conduction energy level of the Ag-NPs compared to that of TiO2 provides trap sites for free charge carriers. Thus, the correlation between the enhancement of the optical absorption and the number of charge traps provided by the Ag-NPs is critical to determine the device performance, especially current density (Jsc) and PCE. This is confirmed by the quantitative comparison of the incident light absorption and the time-resolved photoluminescence decay according to the loading levels of the Ag-NPs in the TiO2 layer. The absorption enhancement from 380 to 750 nm in the UV-visible spectrum is proportional to the increase in the loading levels of the Ag-NPs. However, the Jsc increases with the device with 0.5 wt % Ag-NPs and gradually decreases with increases in the loading level above 0.5 wt % because of the different contributions to the absorbance and the charge trapping by different Ag-NP loading levels. In addition, the suppression of the surface roughness with dense packing by the Ag-NPs helps to improve the Jsc and the following PCE. Consequently, the PCE of the PSC with 0.5 wt % Ag-NPs is increased to 11.96%. These results are attributed to the balance between increased absorbance by the localized surface plasmon resonance and the decreased charge trapping as well as the decreased surface roughness of the TiO2 layer with the Ag-NPs.

  12. Surface enhanced Raman spectroscopy in nanofibers mats of SiO2-TiO2-Ag

    Directory of Open Access Journals (Sweden)

    José Hafid Roque-Ruiz

    Full Text Available Surface-enhanced Raman scattering (SERS is a powerful tool with high potential for detection of dilute analytes. Nanofibers functionalized by metal nanostructures and particles are exploited as effective flexible substrates for SERS analysis. SERS-active substrates of silice-titania-silver (SiO2-TiO2-Ag nanofibers were prepared using a simple approach involving electrospinning. We report a simple method for quantitative SERS analysis using SiO2-TiO2-Ag nanofibers as the SERS substrate. Precursors SiO2 and TiO2 were synthetized through the sol-gel method and then incorporated into a polymeric PVP matrix; later they were processed by coaxial electrospinning to obtain fibers with an average diameter of 250 nm. The SiO2-TiO2-Ag structure was demonstrated by Raman, XRD, IR, SEM and EDX. Through infrared spectroscopy it was possible to evaluate the thermal evolution of the sol-gel process. The Titania phase transformation was observed around 800 °C and the hydroxyl group loss was detected between 500 and 800 °C. The presence of two Titania phases, anatase and rutile were analized with DRX. Using Pyridine (1 nM as probe molecule the SERS effect of the scaffold was evaluated and it was determined that the vibration modes 8a, 8b, and 15 were the most amplified signals with a 3 orders of magnitude factor. With this it was concluded that the Silica-Titania-Silver Scaffold is a feasible as a SERS enhancer. Keywords: Electrospinning, Sol-gel, SERS

  13. Surface enhanced Raman spectroscopy in nanofibers mats of SiO2-TiO2-Ag

    Science.gov (United States)

    Roque-Ruiz, José Hafid; Martínez-Máynez, Héctor; Zalapa-Garibay, Manuela Alejandra; Arizmendi-Moraquecho, Ana; Farias, Rurik; Reyes-López, Simón Yobanny

    Surface-enhanced Raman scattering (SERS) is a powerful tool with high potential for detection of dilute analytes. Nanofibers functionalized by metal nanostructures and particles are exploited as effective flexible substrates for SERS analysis. SERS-active substrates of silice-titania-silver (SiO2-TiO2-Ag) nanofibers were prepared using a simple approach involving electrospinning. We report a simple method for quantitative SERS analysis using SiO2-TiO2-Ag nanofibers as the SERS substrate. Precursors SiO2 and TiO2 were synthetized through the sol-gel method and then incorporated into a polymeric PVP matrix; later they were processed by coaxial electrospinning to obtain fibers with an average diameter of 250 nm. The SiO2-TiO2-Ag structure was demonstrated by Raman, XRD, IR, SEM and EDX. Through infrared spectroscopy it was possible to evaluate the thermal evolution of the sol-gel process. The Titania phase transformation was observed around 800 °C and the hydroxyl group loss was detected between 500 and 800 °C. The presence of two Titania phases, anatase and rutile were analized with DRX. Using Pyridine (1 nM) as probe molecule the SERS effect of the scaffold was evaluated and it was determined that the vibration modes 8a, 8b, and 15 were the most amplified signals with a 3 orders of magnitude factor. With this it was concluded that the Silica-Titania-Silver Scaffold is a feasible as a SERS enhancer.

  14. Surface modification of nanoporous alumina layers by deposition of Ag nanoparticles. Effect of alumina pore diameter on the morphology of silver deposit and its influence on SERS activity

    Energy Technology Data Exchange (ETDEWEB)

    Pisarek, Marcin, E-mail: mpisarek@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, 01-224 (Poland); Nowakowski, Robert [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, 01-224 (Poland); Kudelski, Andrzej [Faculty of Chemistry, University of Warsaw, Pasteur 1, Warsaw, 02-093 (Poland); Holdynski, Marcin; Roguska, Agata; Janik-Czachor, Maria [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, 01-224 (Poland); Kurowska-Tabor, Elżbieta; Sulka, Grzegorz D. [Department of Physical Chemistry and Electrochemistry, Jagiellonian University, Ingardena 3, Cracow, 30-060 (Poland)

    2015-12-01

    Graphical abstract: - Highlights: • Magnetron sputtering of Ag is a suitable method of producing a SERS-active substrate. • Morphology of nanoporous substrate is crucial in the resulting of SERS activity. • Free Ag-NPs act as surface nanoresonators for pyridine molecules. - Abstract: Self-organized Al{sub 2}O{sub 3} nanoporous/nanotubular (Al{sub 2}O{sub 3}-NP) oxide layers decorated with silver nanoparticles (Ag-NPs) exhibiting specific properties may serve as attractive SERS substrates for investigating the interactions between an adsorbate and adsorbent, or as stable platforms for detecting various organic compounds. This article presents the influence of the size of the alumina nanopores with a deposit of silver nanoparticles obtained by the magnetron sputtering technique on the morphology of silver film. Moreover, the effect of pore diameter on the intensity of SERS spectra in Ag-NPs/Al{sub 2}O{sub 3}-NP/Al composites has also been estimated. For such investigations we used pyridine as a probe molecule, since it has a large cross-section for Raman scattering. To characterize the morphology of the composite oxide layer Ag-NPs/Al{sub 2}O{sub 3}-NP/Al, before and after deposition of Ag-NPs by PVD methods (Physical Vapor Deposition), we used scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface analytical technique of surface-enhanced Raman spectroscopy (SERS) was used to investigate the surface activity of the composite. The results obtained show that, for a carefully controlled amount of Ag (0.020 mg/cm{sup 2} - deposited on the top of alumina nanopores whose average size varies from ∼86 nm up to ∼320 nm) in the composites investigated, pore size significantly affects SERS enhancement. We obtained distinctly higher intensities of SERS spectra for substrates with an Ag-NPs deposit having a larger diameter of the alumina nanopores. AFM results suggest that both the lateral and perpendicular distribution of Ag-NPs within and on

  15. Influence of Group-III-metal and Ag adsorption on the Ge growth on Si(111) and its vicinal surface

    Energy Technology Data Exchange (ETDEWEB)

    Speckmann, Moritz

    2011-12-15

    the latter ones are terminated by (111), (013) and (103) side facets as well as a (112) top facet. Ga and In have a contrary impact on the Ge diffusion on the Si(112) surface. While Ga reduces the diffusion for Ge atoms, compared to the growth on the bare Si(112) surface, In increases the diffusion. For the first time Ag was employed as surfactant material for Ge growth on Si. On a completely ({radical}(3) x {radical}(3))-R 30 -Ag covered Si(111) surface a drastic increase of the diffusion length for Ge and, thus, the growth of huge Ge islands (sizes of several {mu}m) is observed. Their density is about three orders of magnitude lower as compared to the growth on the clean Si(111) surface. At a coverage of around 90 bilayers (layer thickness of around 28 nm) the islands are coalesced and a closed Ge film is formed. Ag deposition on both, Si(112) and Si(113), induces the formation of a regular array of nanometer-scale facets along the [110] direction, the sizes of which are dependent on the growth temperature and a maximum periodicity perpendicular to [110] of 55 nm is determined. On Si(112) the array consists of alternating (111) and (113) facets, whereas on Si(113) alternating (111) and (115) facets are found. Subsequently deposited Ge grows nicely along the direction of the facets. Thereby, Ge nanowires with lengths of up to 600 nm and aspect ratios of up to 10:1 are formed.

  16. Seroprevalence of hepatitis B virus infection and seroconvertion to anti-HBsAg in laboratory staff in Goiânia, Goiás Soroprevalência da infecção pelo vírus da hepatite B e soroconversão para anti-HBsAg em profissionais de laboratório em Goiânia, Goiás

    Directory of Open Access Journals (Sweden)

    Paula Andréia Silva

    2005-04-01

    Full Text Available Were analyzed 648 serum samples from laboratory staff in Goiânia, Goiás aiming detection of three serological markers of HBV: HBsAg, anti-HBsAg and anti-HBcAg. The HBsAg and anti-HBcAg positive samples were also analyzed for HBeAg, anti-HBeAg and anti-HBcAgIgM markers. HBV infection rate of 24.1% was observed and, from them, 0.7% were positive for HBsAg. Viral DNA was detected by PCR in two HBsAg positive samples. A vaccination index of 74.5% and a global index of 89.9% of serological response to vaccination were observed. The direct work with biological fluids as well as cleaning workers represented significant risks for acquisition of HBV infection. The data from the present study showed an increase of the vaccination index among laboratory staff but the rates of HBV infection did not change through the years in the region.Neste estudo, foram analisadas 648 amostras de soro, provenientes de profissionais de laboratório de Goiânia-Goiás, visando a detecção de três marcadores sorológicos do VHB: HBsAg, anti-HBsAg e anti-HBcAg. As amostras HBsAg e anti-HBcAg positivas foram também analisadas para os marcadores HBeAg, anti-HBeAg e anti-HBcAgIgM. Foi observado um percentual de soropositividade para infecção pelo VHB de 24,1% sendo que 0,7% destes foram positivos para o HBsAg. O DNA viral foi detectado por PCR nas duas amostras HBsAg positivas. Dos 648 profissionais, 74,5% relataram vacinação para o VHB e, destes, 89,9% apresentaram soroconversão. Trabalho direto com fluidos biológicos bem como trabalho em serviços gerais representaram risco significativo para aquisição da infecção pelo VHB. Os resultados do estudo mostram que embora tenha havido um aumento no índice de vacinação entre os trabalhadores de laboratório, o índice de infecção pelo VHB manteve-se inalterado em relação ao tempo na região.

  17. Cationic lipid-formulated DNA vaccine against hepatitis B virus: immunogenicity of MIDGE-Th1 vectors encoding small and large surface antigen in comparison to a licensed protein vaccine.

    Directory of Open Access Journals (Sweden)

    Anne Endmann

    Full Text Available Currently marketed vaccines against hepatitis B virus (HBV based on the small (S hepatitis B surface antigen (HBsAg fail to induce a protective immune response in about 10% of vaccinees. DNA vaccination and the inclusion of PreS1 and PreS2 domains of HBsAg have been reported to represent feasible strategies to improve the efficacy of HBV vaccines. Here, we evaluated the immunogenicity of SAINT-18-formulated MIDGE-Th1 vectors encoding the S or the large (L protein of HBsAg in mice and pigs. In both animal models, vectors encoding the secretion-competent S protein induced stronger humoral responses than vectors encoding the L protein, which was shown to be retained mainly intracellularly despite the presence of a heterologous secretion signal. In pigs, SAINT-18-formulated MIDGE-Th1 vectors encoding the S protein elicited an immune response of the same magnitude as the licensed protein vaccine Engerix-B, with S protein-specific antibody levels significantly higher than those considered protective in humans, and lasting for at least six months after the third immunization. Thus, our results provide not only the proof of concept for the SAINT-18-formulated MIDGE-Th1 vector approach but also confirm that with a cationic-lipid formulation, a DNA vaccine at a relatively low dose can elicit an immune response similar to a human dose of an aluminum hydroxide-adjuvanted protein vaccine in large animals.

  18. XPS study of the surface chemistry of Ag-covered L-CVD SnO2 thin films

    International Nuclear Information System (INIS)

    Kwoka, M.; Ottaviano, L.; Passacantando, M.; Czempik, G.; Santucci, S.; Szuber, J.

    2008-01-01

    In this paper, we present the results of X-ray photoelectron spectroscopy characterization of SnO 2 thin films prepared by laser chemical vapour deposition (L-CVD) and subsequently covered by Ag atoms just after deposition and after long-term exposed to dry air, subsequent annealing in ultra high vacuum at 400 deg. C and dry air oxidation at 400 deg. C. Using the standard analytical procedure based on atomic sensitivity factors, the variation of surface chemistry defined in terms of the relative concentration of the main components of the films after the above-mentioned procedures has been determined. It was confirmed that after dry air exposure as well as dry air oxidation, the layers undergo an oxidation reaching almost SnO 2 stoichiometry. Besides, during ultra high vacuum annealing, the films undergo reduction to almost SnO stoichiometry. At the same time, Ag atoms deposited at the top of layers diffuse into the subsurface layers. This was confirmed by X-ray photoelectron spectroscopy depth profiling analysis

  19. Enhancement of atom transfer in different surface chemistry of hydrogenated vs. fluorinated tribromobenzene on Ag(111) and Cu(111)

    Science.gov (United States)

    Cecily mary glory, D.; Sambathkumar, K.; Madivanane, R.; Rajkamal, N.; Venkatachalapathy, M.

    2017-12-01

    Systematic interactions of hydrogenated & fluorinated tribromobenzene on Ag and Cu surfaces. First bromine dehalogenation takes place right upon adsorption due to catalytic properties of Ag. Different adsorption geometries of monomers and dimmers of 1,3,5-tribromo-2,4,6-trifluoro-benzene(TBFB) and 1,3,5-tribromobenzene(TBB). DFT calculations of the Csbnd Br binding energy dependent on the amount of remaining bromine atoms for both TBFB and TBB were performed. The experiments were performed at low temperature of 80 K.STM measurements where performed for of TBFB and TBB. STM show adsorbed molecules in a loose arrangement of molecules. NBO analysis the stability of the molecule arising within hyper-conjugative interactions. The HOMO and LUMO energies and electronic charge transfer (ECT) confirms that electronic transition. High field indicates that this molecule exhibit considerable electrical conductivity in atomic charges. The ESP map is found to be positive within the molecule. The negative charges have a tendency to drift from left to right. The computed thermodynamic parameters like heat capacities (Cºp,m), entropies (Sºm) and enthalpies changes (Hºm) are used for various electrical field.

  20. Theoretical and photo-electrochemical studies of surface plasmon induced visible light absorption of Ag loaded TiO2 nanotubes for water splitting

    Science.gov (United States)

    Gross, P. A.; Javahiraly, N.; Geraldini Sabat, N.; Cottineau, T.; Savinova, E. R.; Keller, V.

    2016-10-01

    Vertically aligned TiO2 nanotubes (TiO2-NTs), obtained by anodization in organic electrolyte, are decorated with 15 nm Ag nanoparticles prepared by a micro-wave assisted polyol synthesis. The Ag/TiO2 system is characterized by electronic microscopies in order to build a Finite Differential Time Domain (FDTD) model to simulate the interaction of light with the system. By combining UV-visible spectroscopy and FDTD simulations, the observed red shift in the surface plasmon resonance wavelength of the Ag nanoparticles, deposited on TiO2, is explained. The Ag/TiO2-NT system is used as photoanode in a photoelectrochemical water splitting setup and shows an increasing Incident Photon to Current Conversion Efficiency (IPCE) in the visible light domain with an increasing amount of deposited Ag. The spectral position of this activity enhancement coincides with the one expected from the FDTD calculations for the surface plasmon resonance of the Ag nanoparticles deposited on TiO2.

  1. Charge transfer driven surface segregation of gold atoms in 13-atom Au-Ag nanoalloys and its relevance to their structural, optical and electronic properties

    International Nuclear Information System (INIS)

    Chen Fuyi; Johnston, Roy L.

    2008-01-01

    The structural, optical and electronic properties of 13-atom Ag-Au nanoalloys are determined by a combination of global optimization using semi-empirical potentials and density functional theory calculations. A family of Au surface-segregated structures are found for core-shell Ag n Au 13-n (n = 1, 2, 3, 5, 7, 8, 9, 12) and hollow Ag n Au 13-n (n = 4, 6, 10, 11) clusters, whose stability is enhanced by directional charge transfer. The atomic ordering in core-shell structures is related to the electric dipole moment and odd-numbered surface Au-atom clusters have high moments. Their ferroelectric and ferromagnetic properties provide a potential approach for tailoring their surface plasmonic modes

  2. Prevalence of Hepatitis B Cab with or Without Anti Hbsab in Hbsag Seronegative Blood Donors

    OpenAIRE

    H Salman Roughani

    2005-01-01

    Introduction: There are multiple reports of Acute Hepatitis B after blood transfusion inspite of good screening for Hepatitis B before transfusion. Therefore, occult hepatitis B is a serious concern for Blood transfusion. There is a lot of evidence that positive HBCAb in seronegative HBSAg blood donors is associated with occult Hepatitis B. Aim: Evaluation of the prevalence of HBCAb in seronegative HBSAg blood donors. Method: In a cross sectional descriptive study, we evaluated the serum of 1...

  3. Synthesis of Ag nanobars in the presence of single-crystal seeds and a bromide compound, and their surface-enhanced Raman scattering (SERS) properties.

    Science.gov (United States)

    Zhang, Qiang; Moran, Christine H; Xia, Xiaohu; Rycenga, Matthew; Li, Naixu; Xia, Younan

    2012-06-19

    This Article describes the synthesis of Ag nanobars with different aspect ratios using a seed-mediated method and evaluation of their use for surface-enhanced Raman scattering (SERS). The formation of Ag nanobars was found to critically depend on the introduction of a bromide compound into the reaction system, with ionic salts being more effective than covalent molecules. We examined single-crystal seeds with both spherical and cubic shapes and found that Ag nanobars grown from spherical seeds had much higher aspect ratios than those grown from cubic seeds. The typical product of a synthesis contained nanocrystals with three different morphologies: nanocubes, nanobars with a square cross section, and nanobars with a rectangular cross section. Their formation can be attributed to the difference in growth rates along the three orthogonal directions. The SERS enhancement factor of the Ag nanobar was found to depend on its aspect ratio, its orientation relative to the laser polarization, and the wavelength of excitation.

  4. Ag coated microneedle based surface enhanced Raman scattering probe for intradermal measurements

    Science.gov (United States)

    Yuen, Clement; Liu, Quan

    2013-06-01

    We propose a silver coated microneedle to detect test molecules, including R6G and glucose, positioned at a depth of more than 700 μm below a skin phantom surface for mimicking intradermal surface-enhanced Raman scattering measurements.

  5. Ag K- and L3-edge XAFS study on Ag species in Ag/Ga2O3 photocatalysts

    International Nuclear Information System (INIS)

    Yamamoto, M; Yamamoto, N; Yoshida, T; Nomoto, T; Yamamoto, A; Yoshida, H; Yagi, S

    2016-01-01

    Ag loaded Ga 2 O 3 (Ag/Ga 2 O 3 ) shows photocatalytic activity for reduction of CO 2 with water. Ag L 3 -edge XANES and K-edge EXAFS spectra were measured for various Ag/Ga 2 O 3 samples, which suggested that structural and chemical states of Ag species varied with the loading amount of Ag and the preparation method. The Ag species were metallic Ag particles with an AgGaO 2 -like interface structure in the sample with high loading amount of Ag while predominantly Ag metal clusters in the sample with low loading amount of Ag. The XANES feature just above the edge represented the interaction between the Ag species and the Ga 2 O 3 surface, showing that the Ag metal clusters had more electrons in the d -orbitals by interacting with the Ga 2 O 3 surface, which would contribute the high photocatalytic activity. (paper)

  6. Replacement of Poly(vinyl pyrrolidone) by Thiols: A Systematic Study of Ag Nanocube Functionalization by Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Moran, Christine H; Rycenga, Matthew; Zhang, Qiang; Xia, Younan

    2011-11-10

    In this work, we used surface-enhanced Raman scattering (SERS) to monitor the replacement of poly(vinyl pyrrolidone) (PVP) on Ag nanocubes by cysteamine, thiol-terminated PEG, and benzenedithiol. PVP is widely used as a colloidal stabilizer and capping agent to control the shape of Ag (as well as many other noble metals) nanocrystals during synthesis, and to stabilize the final colloidal suspension. However, the surface chemistry of Ag nanocrystals often needs to be tailored for specific applications, so the PVP coating must be removed and/or replaced by other ligands. By monitoring the signature peak from the carbonyl groups of PVP, we show, for the first time, that the PVP adsorbed on the surface of Ag nanocubes was completely replaced by the thiol molecules at room temperature over the course of a few hours. We observed the same trend no matter if the Ag nanocubes were suspended in an aqueous solution of the thiol or supported on a silicon substrate and then immersed in the thiol solution.

  7. Au-Protected Ag Core/Satellite Nanoassemblies for Excellent Extra-/Intracellular Surface-Enhanced Raman Scattering Activity.

    Science.gov (United States)

    Zhang, Zhiqiang; Bando, Kazuki; Taguchi, Atsushi; Mochizuki, Kentaro; Sato, Kazuhisa; Yasuda, Hidehiro; Fujita, Katsumasa; Kawata, Satoshi

    2017-12-20

    Silver nanoparticles (AgNPs) and their assembled nanostructures such as core/satellite nanoassemblies are quite attractive in plasmonic-based applications. However, one biggest drawback of the AgNPs is the poor chemical stability which also greatly limits their applications. We report fine Au coating on synthesized quasi-spherical silver nanoparticles (AgNSs) with few atomic layers to several nanometers by stoichiometric method. The fine Au coating layer was confirmed by energy-dispersive X-ray spectroscopy elemental mapping and aberration-corrected high-angle annular dark-field scanning transmission electron microscopy. The optimized minimal thickness of Au coating layer on different sized AgNSs (22 nm Ag@0.9 nm Au, 44 nm Ag@1.8 nm Au, 75 nm Ag@2.9 nm Au, and 103 nm Ag@0.9 nm Au) was determined by extreme chemical stability tests using H 2 O 2 , NaSH, and H 2 S gas. The thin Au coating layer on AgNSs did not affect their plasmonic-based applications. The core/satellite assemblies based on Ag@Au NPs showed the comparable SERS intensity and uniformity three times higher than that of noncoated Ag core/satellites. The Ag@Au core/satellites also showed high stability in intracellular SERS imaging for at least two days, while the SERS of the noncoated Ag core/satellites decayed significantly. These spherical Ag@Au NPs can be widely used and have great advantages in plasmon-based applications, intracellular SERS probes, and other biological and analytical studies.

  8. The controlled pulsed laser deposition of Ag nanoparticle arrays for surface enhanced Raman scattering.

    Science.gov (United States)

    D'Andrea, C; Neri, F; Ossi, P M; Santo, N; Trusso, S

    2009-06-17

    An effective method for the production of surface enhanced Raman scattering (SERS) active substrates is presented. Nanostructured silver thin films are pulsed laser deposited in an argon atmosphere. The films consist of arrays of nanoparticles whose size is controlled by the Ar pressure. The surface morphology of the films can be tuned by the laser pulse number. Nanoparticle size is calculated by a phenomenological model taking into account the dynamics of the laser generated silver plasma. The SERS activity of the films is investigated by Raman scattering of adsorbed rhodamine 6G at different concentrations.

  9. Direct evidence and enhancement of surface plasmon resonance effect on Ag-loaded TiO2 nanotube arrays for photocatalytic CO2 reduction

    Science.gov (United States)

    Low, Jingxiang; Qiu, Shuoqi; Xu, Difa; Jiang, Chuanjia; Cheng, Bei

    2018-03-01

    Surface plasmon resonance (SPR) effect has been utilized in many solar conversion applications because of its ability to convert visible photons into "hot electron" energy. However, the direct evidence and enhancement of this unique effect are still great challenges, limiting its practical applications. Here we present the direct evidence and enhancement of SPR effect using TiO2 nanotube arrays (TNTAs) loaded with Ag nanoparticles (NPs) as a proof-of-concept example. Particularly, electrochemical deposition method is applied to deposit Ag NPs into the inner space of TNTAs for enhancing SPR effect of Ag NPs, as demonstrated by Raman and light absorption spectroscopies. This enhanced SPR effect is because multi-scattered light within TNTAs can be effectively utilized by Ag NPs in the inner space of TNTAs. Moreover, combining synchronous-illumination X-ray photoelectron and electrochemical impedance spectroscopy characterization, we confirm that the SPR effect of Ag NPs can enhance photocatalytic performance of TNTAs mainly from two aspects: (i) injection of "hot electrons" from Ag NPs to TNTAs and (ii) acceleration of charge carrier migration on the TNTAs through a unique near field effect. The direct evidence and enhancement of SPR effect open new perspectives in design of functional plasmonic nanomaterials with high solar conversion efficiency.

  10. Characterization of Ag-porous silicon nanostructured layer formed by an electrochemical etching of p-type silicon surface for bio-application

    Science.gov (United States)

    Naddaf, M.; Al-Mariri, A.; Haj-Mhmoud, N.

    2017-06-01

    Nanostructured layers composed of silver-porous silicon (Ag-PS) have been formed by an electrochemical etching of p-type (1 1 1) silicon substrate in a AgNO3:HF:C2H5OH solution at different etching times (10 min-30 min). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) results reveal that the produced layers consist of Ag dendrites and a silicon-rich porous structure. The nanostructuring nature of the layer has been confirmed by spatial micro-Raman scattering and x-ray diffraction techniques. The Ag dendrites exhibit a surface-enhanced Raman scattering (SERS) spectrum, while the porous structure shows a typical PS Raman spectrum. Upon increasing the etching time, the average size of silicon nanocrystallite in the PS network decreases, while the average size of Ag nanocrystals is slightly affected. In addition, the immobilization of prokaryote Salmonella typhimurium DNA via physical adsorption onto the Ag-PS layer has been performed to demonstrate its efficiency as a platform for detection of biological molecules using SERS.

  11. A novel surface plasmon resonance biosensor based on the PDA-AgNPs-PDA-Au film sensing platform for horse IgG detection

    Science.gov (United States)

    Wang, Ning; Zhang, Di; Deng, Xinyu; Sun, Ying; Wang, Xinghua; Ma, Pinyi; Song, Daqian

    2018-02-01

    Herein we report a novel polydopamine-silver nanoparticle-polydopamine-gold (PDA-AgNPs-PDA-Au) film based surface plasmon resonance (SPR) biosensor for horse IgG detection. The PDA-AgNPs-PDA-Au film sensing platform was built on Au-film via layer-by-layer self-assembly. Ag ion was reduced in situ to AgNPs in presence of PDA. The top PDA layer can prevent AgNPs from being oxidized and connect with antibody via Schiff alkali reaction directly. The morphology and thickness of the modified gold film were characterized using scanning electron microscope and Talystep. Experimental results show that the PDA-AgNPs-PDA-Au film sensing platform is stable, regenerative and sensitive for horse IgG detection. The detection limit of horse IgG obtained with the present biosensor is 0.625 μg mL- 1, which is 2-fold and 4-fold lower than that obtained with biosensor based on PDA modified Au film and conventional biosensor based on MPA, respectively. Furthermore, when challenged to real serum samples, our sensor exhibited excellent specificity to horse IgG, suggesting its potential for industrial application.

  12. Toward the Synthesis of Sub-15 nm Ag Nanocubes with Sharp Corners and Edges: The Roles of Heterogeneous Nucleation and Surface Capping.

    Science.gov (United States)

    Ruditskiy, Aleksey; Xia, Younan

    2016-03-09

    We report a polyol method for the facile synthesis of Ag nanocubes having sharp corners and edges, together with edge lengths below 15 nm. The rapid nucleation of Ag atoms was facilitated through the addition of a trace amount of SH(-) to generate Ag2S clusters while the corners and edges of the nanocubes were sharpened through the introduction of Br(-) as a regulator of the growth kinetics and a capping agent for the Ag(100) surface. Because of their much smaller size relative to the more commonly used capping agent based on poly(vinylpyrrolidone), Br(-) ions are more effective in passivating the {100} facets on very small Ag nanocubes. The mechanistic roles of these additives, along with the effects of their interactions with other species present in the reaction solution, were all systematically investigated. The concentration of SH(-) was found to be a particularly effective parameter for tuning the edge length of the nanocubes. As a result of the understanding gained during the course of this study, Ag nanocubes with uniform edge lengths controllable in the range of 13-23 nm could be reliably produced. The nanocubes of 13.4 ± 0.4 nm in edge length constitute the smallest nanocrystals of this kind reported to date; they also possess sharper corners and edges relative to the limited examples of sub-20 nm Ag nanocubes reported in the literature. The availability of such small and sharp Ag nanocubes will open the door to an array of applications in plasmonics, catalysis, and biomedicine.

  13. Transformação de plantas de tabaco (Nicotiana tabacum L.) com os genes recombinantes 35SHBsAg e 35SHBsAgER do vírus da hepatite B

    OpenAIRE

    Ribeiro, Juliana Martins; Bastos, Débora Costa; Oliveira, Eduardo Alves Gamosa de; Souza, Jackson Antônio Marcondes de; Pinto, Márcio dos Santos Teixeira; Hansen, Ekkehard Ernst Theodor

    2010-01-01

    http://dx.doi.org/10.5007/2175-7925.2010v23n1p1 O antígeno de superfície do vírus da hepatite B (HBsAg) recombinante, purificado de plantas transgênicas, mostrou-se bastante eficiente quando utilizado para a indução da produção de anticorpos anti-HBs para a prevenção da hepatite B. Devido ao importante papel demonstrado pelo antígeno HBsAg para a prevenção da hepatite B, a sequência codificadora do antígeno HBsAg, adicionada ou não da sequência carboxi-terminal para retenção da proteína n...

  14. Decay mechanism of double-layer islands on close-packed surfaces: Silver on Ag(111) and copper on Cu(111)

    International Nuclear Information System (INIS)

    Gong Xiufang; Hu Biao; Ning Xijing; Zhuang Jun

    2005-01-01

    Molecular dynamics simulations are preformed to investigate the diffusion behaviors of double-layer islands on close-packed surfaces: Ag on Ag(111) and Cu on Cu(111), showing that the top layer moves mostly via concerted motions with its shape unchanged, and the top-layer atoms descend into the lower layer mainly by two-atom exchange only when they move to the verge of the lower layer. Especially, once a descent event takes place, other atoms of the top layer descend frequently at the same place in a short period. Compared to the Cu system, the dragging and the reattachment events take place much more frequently on the Ag surface and the Ag top layer shows a stronger tendency to form a compact configuration, e.g., a hexagon, by dragging one or two atoms from the lower layer, or even the Ag island can change from the initial double-layer into a three-layer structure due to upward diffusions

  15. HBsAg-redirected T cells exhibit antiviral activity in HBV-infected human liver chimeric mice.

    Science.gov (United States)

    Kruse, Robert L; Shum, Thomas; Tashiro, Haruko; Barzi, Mercedes; Yi, Zhongzhen; Whitten-Bauer, Christina; Legras, Xavier; Bissig-Choisat, Beatrice; Garaigorta, Urtzi; Gottschalk, Stephen; Bissig, Karl-Dimiter

    2018-04-06

    Chronic hepatitis B virus (HBV) infection remains incurable. Although HBsAg-specific chimeric antigen receptor (HBsAg-CAR) T cells have been generated, they have not been tested in animal models with authentic HBV infection. We generated a novel CAR targeting HBsAg and evaluated its ability to recognize HBV+ cell lines and HBsAg particles in vitro. In vivo, we tested whether human HBsAg-CAR T cells would have efficacy against HBV-infected hepatocytes in human liver chimeric mice. HBsAg-CAR T cells recognized HBV-positive cell lines and HBsAg particles in vitro as judged by cytokine production. However, HBsAg-CAR T cells did not kill HBV-positive cell lines in cytotoxicity assays. Adoptive transfer of HBsAg-CAR T cells into HBV-infected humanized mice resulted in accumulation within the liver and a significant decrease in plasma HBsAg and HBV-DNA levels compared with control mice. Notably, the fraction of HBV core-positive hepatocytes among total human hepatocytes was greatly reduced after HBsAg-CAR T cell treatment, pointing to noncytopathic viral clearance. In agreement, changes in surrogate human plasma albumin levels were not significantly different between treatment and control groups. HBsAg-CAR T cells have anti-HBV activity in an authentic preclinical HBV infection model. Our results warrant further preclinical exploration of HBsAg-CAR T cells as immunotherapy for HBV. Copyright © 2018 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  16. RHEED studies of the nucleation, growth, and mobility of Ag atoms on the Si(111)7 x 7 surface

    Energy Technology Data Exchange (ETDEWEB)

    Roos, Kelly Ryan [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    The low temperature and flux dependent growth of ultrathin Ag films on the Si(111)7x7 surface is studied with Reflection High-Energy Electron Diffraction (RHEED). The grazing incidence geometry of RHEED allows for an incident molecular beam normal to the surface, and makes it an ideal surface probe for studying ultrathin film growth in real time. Short-lived oscillations in the diffracted intensity are observed during Ag deposition at 150 K, indicating quasi-layer-by-layer growth mediated by adatom mobility. When the 150 K growth is performed over a wide range of deposition rates F, the peak intensity is observed to scale, i.e. I(Ft) depends only on the total amount deposited, which implies thermally activated diffusion is absent at 150 K. Scaling is not obeyed at higher temperatures (T≥473 K) for the growth of the √3x√3 R30° (√3) superstructure. Testing for scaling of the diffracted intensity constitutes a new experimental method which can be applied generally to determine if thermal diffusion is active at a particular temperature. Scaling is consistent with a constant diffusion length R0, independent of substrate temperature and deposition rate. The presence of a non-thermal diffusion mechanism (responsible for the constant diffusion length R0) is confirmed by monitoring the flux dependence of the √3 superstructure growth during deposition at T≥473 K. At these temperatures the total diffusion length R is given by R=R0+(4Dt)1/2, where (4Dt)1/2 is the thermal component. A non-zero intercept R0 is found by plotting the peak intensity Ip1/2 (a measure of the average domain size) vs. deposition rate F-1/2 (F-1 is proportional to the available diffusion time.) From the FWHM of a low coverage (0.2 ML) √3 spot, an estimation of 50 Å is made for a lower bound of the magnitude of R0.

  17. RHEED studies of the nucleation, growth, and mobility of Ag atoms on the Si(111)7 x 7 surface

    International Nuclear Information System (INIS)

    Roos, K.R.

    1993-07-01

    The low temperature and flux dependent growth of ultrathin Ag films on the Si(111)7x7 surface is studied with Reflection High-Energy Electron Diffraction (RHEED). The grazing incidence geometry of RHEED allows for an incident molecular beam normal to the surface, and makes it an ideal surface probe for studying ultrathin film growth in real time. Short-lived oscillations in the diffracted intensity are observed during Ag deposition at 150 K, indicating quasi-layer-by-layer growth mediated by adatom mobility. When the 150 K growth is performed over a wide range of deposition rates F, the peak intensity is observed to scale, i.e. I(Ft) depends only on the total amount deposited, which implies thermally activated diffusion is absent at 150 K. Scaling is not obeyed at higher temperatures (T≥473 K) for the growth of the √3x√3 R30 degrees (√3) superstructure. Testing for scaling of the diffracted intensity constitutes a new experimental method which can be applied generally to determine if thermal diffusion is active at a particular temperature. Scaling is consistent with a constant diffusion length R 0 , independent of substrate temperature and deposition rate. The presence of a non-thermal diffusion mechanism (responsible for the constant diffusion length R 0 ) is confirmed by monitoring the flux dependence of the √3 superstructure growth during deposition at T≥473 K. At these temperatures the total diffusion length R is given by R=R 0 +(4Dt) 1/2 , where (4Dt) 1/2 is the thermal component. A non-zero intercept R 0 is found by plotting the peak intensity I p 1/2 (a measure of the average domain size) vs. deposition rate F -1/2 (F -1 is proportional to the available diffusion time.) From the FWHM of a low coverage (0.2 ML) √3 spot, an estimation of 50 angstrom is made for a lower bound of the magnitude of R 0

  18. Comparison of hepatitis E virus seroprevalence between HBsAg-positive population and healthy controls in Shandong province, China.

    Science.gov (United States)

    Zhang, Li; Jiang, Zechun; Lv, Jingjing; Liu, Jiaye; Yan, Bingyu; Feng, Yi; Li, Li; Zhang, Guomin; Wang, Fuzhen; Xu, Aiqiang

    2018-02-12

    Persons with chronic hepatitis B (CHB) infection were reported to suffer severe disease after hepatitis E virus (HEV) superinfection, but the studies regarding HEV seroprevalence in this population were limited. A recent study in Vietnam found higher HEV seroprevalence among CHB patients compared with healthy controls. A community-based case-control study was conducted in two counties of Shandong province, China, where hepatitis E incidence was at the highest (Rushan) and lowest (Zhangqiu) in the province based on data from routine public health surveillance. Four townships were selected randomly from each county and all residents in these townships were tested for hepatitis B surface antigen (HBsAg). Those tested positive for HBsAg (CHB group) and the 1:1 age and sex-matched HBsAg-negative residents (control group) were included. Anti-HEV IgM and IgG were tested and positive rates of IgG and IgM were compared between the CHB group and the control group. In total, 2048 CHB participants and 2054 controls were included in the study. In the CHB group, HEV IgG seroprevalence was 9.16% (95% CI: 7.47-11.09) in Zhangqiue and 38.06% (95% CI: 35.07-41.19) in Rushan (P < 0.001); the corresponding rates of IgM were 0.1% (95% CI: 0.002-0.54) and 1.57% (95% CI: 0.90-2.53), respectively (P < 0.001). HEV IgG seroprevalence was similar between CHB group and the control group in both counties (P = 0.21, P = 0.47, respectively) and the same results were found for the positive rate of IgM (P = 0.103, P = 0.262, respectively). Multivariable analysis showed the status of HBsAg was not independently associated with the status of anti-HEV IgG in either Zhangqiu or Rushan [P = 0.187, OR = 1.23(95% CI: 0.90, 1.68); P = 0.609, OR = 1.05 (95% CI: 0.87, 1.26)]. The seroprevalence of HEV varies greatly in different geographic areas, but the seroprevalence is similar between populations with and without CHB. CHB patients residing in high HEV endemic areas

  19. Lateral manipulation of small clusters on the Cu and Ag(1 1 1) surfaces with the single-atom and trimer-apex tips: Reliability study

    International Nuclear Information System (INIS)

    Xie Yiqun; Liu Fen; Huang Lei

    2010-01-01

    We study the reliability of the lateral manipulation of small Cu clusters (dimer and trimer) on the flat Cu(1 1 1) surface with both the single-atom and trimer-apex tips and that for the Ag/Ag(1 1 1) system, and compare the results between the two systems as well as with the single-atom manipulation on these surfaces. Manipulations are simulated using molecular statics method with semi-empirical potentials. The dependence of the manipulation reliability on the tip height and tip orientation are investigated. Overall, the manipulation reliability increases with decreasing tip height although it depends obviously on the tip orientation. For the Cu/Cu(1 1 1) system, the manipulation of the dimmer and trimer can be successful with both tips. The manipulation reliability can be improved by the trimer-apex tip, and the tip-height range for the successful manipulation is also broader, as compared to the single-atom apex tip. Differently from the single-atom manipulation, the tip orientation has a noticeable influence on the manipulation reliability even for the single-atom tip due to the stronger tip-cluster and surface-adatom interactions in cluster manipulation. For the Ag/Ag(1 1 1) system, successful manipulations only be achieved with the trimer-apex tip, and the manipulation reliability is worse than that of the Cu/Cu(1 1 1) system, indicating the difference in mechanic properties between the two surfaces at the atomic level.

  20. Surface protein mutations in chronic hepatitis B patients who received hepatitis B vaccine therapy

    Science.gov (United States)

    Daram, Maryam; Montazeri, Ghodratollah; Karimzadeh, Hadi; Malekzadeh, Reza; Mahmoodi, Mahmood; Goodarzi, Zahra; Keyvani, Hossein; Mirmomen, Shahram; Alavian, Seyed Moayed; Roggendorf, Michael; Jazayeri, Seyed Mohammad

    2014-01-01

    Objective (s): The aim of this study was to determine the correlation between vaccine therapy and appearance of mutations in hepatitis B surface antigen (HBsAg)-positive chronic hepatitis B virus (HBV) patients. Materials and Methods: 16 patients received the HBV vaccine and another 16 individuals from the control group did not. The surface gene was amplified and directly sequenced from samples prior to vaccination and six months after the third dose. Results: Only one patient lost HBsAg. 48 and 44 amino acid mutations were found before and after vaccine therapy in the vaccine group respectively, 51 of which (55.4%) occurred in immune epitopes: 5 were in B cell, 21 in T helper (Th), and 25 in cytotoxic T-lymphocyte (CTL) epitopes. In the control group, 35 and 41 amino acid substitutions were found before and after therapy, respectively. 32 (42%) of 76 amino acid changes occurred within immune epitopes. There were no differences in age, gender, and duration of chronicity in both patient and control groups in terms of the frequency and the patterns of mutations. Conclusion: In chronic carriers who already had HBsAg variants selected by the host-immune response, any immune stimulation by the vaccine had no effect on the chronic state of these patients or selected any remarkable escape mutants. Newer strategies should be considered based on third generation or the use of DNA vaccines or new adjuvants. PMID:25691938

  1. N-Heterocyclic carbenes on close-packed coinage metal surfaces: bis-carbene metal adatom bonding scheme of monolayer films on Au, Ag and Cu.

    Science.gov (United States)

    Jiang, Li; Zhang, Bodong; Médard, Guillaume; Seitsonen, Ari Paavo; Haag, Felix; Allegretti, Francesco; Reichert, Joachim; Kuster, Bernhard; Barth, Johannes V; Papageorgiou, Anthoula C

    2017-12-01

    By means of scanning tunnelling microscopy (STM), complementary density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) we investigate the binding and self-assembly of a saturated molecular layer of model N -heterocyclic carbene (NHC) on Cu(111), Ag(111) and Au(111) surfaces under ultra-high vacuum (UHV) conditions. XPS reveals that at room temperature, coverages up to a monolayer exist, with the molecules engaged in metal carbene bonds. On all three surfaces, we resolve similar arrangements, which can be interpreted only in terms of mononuclear M(NHC) 2 (M = Cu, Ag, Au) complexes, reminiscent of the paired bonding of thiols to surface gold adatoms. Theoretical investigations for the case of Au unravel the charge distribution of a Au(111) surface covered by Au(NHC) 2 and reveal that this is the energetically preferential adsorption configuration.

  2. Topological states in a two-dimensional metal alloy in Si surface: BiAg/Si(111)-4 ×4 surface

    Science.gov (United States)

    Zhang, Xiaoming; Cui, Bin; Zhao, Mingwen; Liu, Feng

    2018-02-01

    A bridging topological state with a conventional semiconductor platform offers an attractive route towards future spintronics and quantum device applications. Here, based on first-principles and tight-binding calculations, we demonstrate the existence of topological states hosted by a two-dimensional (2D) metal alloy in a Si surface, the BiAg/Si(111)-4 ×4 surface, which has already been synthesized experimentally. It exhibits a topological insulating state with an energy gap of 71 meV (˜819 K ) above the Fermi level and a topological metallic state with quasiquantized conductance below the Fermi level. The underlying mechanism leading to the formation of such nontrivial states is revealed by analysis of the "charge-transfer" and "orbital-filtering" effect of the Si substrate. A minimal effective tight-binding model is employed to reveal the formation mechanism of the topological states. Our finding opens opportunities to detect topological states and measure its quantized conductance in a large family of 2D surface metal alloys, which have been or are to be grown on semiconductor substrates.

  3. Influence of near-field coupling from Ag surface plasmons on InGaN/GaN quantum-well photoluminescence

    International Nuclear Information System (INIS)

    Fadil, Ahmed; Iida, Daisuke; Chen, Yuntian; Ou, Yiyu; Kamiyama, Satoshi; Ou, Haiyan

    2016-01-01

    We have investigated the borderline between photoluminescence quenching and enhancement of InGaN/GaN quantum-wells due to Ag nanoparticles and their surface plasmon modes. By embedding Ag nanoparticles inside nanohole structures on the p-type layer GaN, luminescence quenching is observed. Increasing the distance between the nanoparticles and quantum-wells has shown to enhance the emission. We have found that the nano-structure geometry of the metal-semiconductor interface in the near-field of the quantum-wells plays a crucial role in determining whether the emitter performance is enhanced or degraded.

  4. Physiological response of Pichia pastoris GS115 to methanol-induced high level production of the Hepatitis B surface antigen: catabolic adaptation, stress responses, and autophagic processes.

    Science.gov (United States)

    Vanz, Ana Leticia; Lünsdorf, Heinrich; Adnan, Ahmad; Nimtz, Manfred; Gurramkonda, Chandrasekhar; Khanna, Navin; Rinas, Ursula

    2012-08-08

    Pichia pastoris is an established eukaryotic host for the production of recombinant proteins. Most often, protein production is under the control of the strong methanol-inducible aox1 promoter. However, detailed information about the physiological alterations in P. pastoris accompanying the shift from growth on glycerol to methanol-induced protein production under industrial relevant conditions is missing. Here, we provide an analysis of the physiological response of P. pastoris GS115 to methanol-induced high-level production of the Hepatitis B virus surface antigen (HBsAg). High product titers and the retention of the protein in the endoplasmic reticulum (ER) are supposedly of major impact on the host physiology. For a more detailed understanding of the cellular response to methanol-induced HBsAg production, the time-dependent changes in the yeast proteome and ultrastructural cell morphology were analyzed during the production process. The shift from growth on glycerol to growth and HBsAg production on methanol was accompanied by a drastic change in the yeast proteome. In particular, enzymes from the methanol dissimilation pathway started to dominate the proteome while enzymes from the methanol assimilation pathway, e.g. the transketolase DAS1, increased only moderately. The majority of methanol was metabolized via the energy generating dissimilatory pathway leading to a corresponding increase in mitochondrial size and numbers. The methanol-metabolism related generation of reactive oxygen species induced a pronounced oxidative stress response (e.g. strong increase of the peroxiredoxin PMP20). Moreover, the accumulation of HBsAg in the ER resulted in the induction of the unfolded protein response (e.g. strong increase of the ER-resident disulfide isomerase, PDI) and the ER associated degradation (ERAD) pathway (e.g. increase of two cytosolic chaperones and members of the AAA ATPase superfamily) indicating that potential degradation of HBsAg could proceed via the

  5. Physiological response of Pichia pastoris GS115 to methanol-induced high level production of the Hepatitis B surface antigen: catabolic adaptation, stress responses, and autophagic processes

    Science.gov (United States)

    2012-01-01

    Background Pichia pastoris is an established eukaryotic host for the production of recombinant proteins. Most often, protein production is under the control of the strong methanol-inducible aox1 promoter. However, detailed information about the physiological alterations in P. pastoris accompanying the shift from growth on glycerol to methanol-induced protein production under industrial relevant conditions is missing. Here, we provide an analysis of the physiological response of P. pastoris GS115 to methanol-induced high-level production of the Hepatitis B virus surface antigen (HBsAg). High product titers and the retention of the protein in the endoplasmic reticulum (ER) are supposedly of major impact on the host physiology. For a more detailed understanding of the cellular response to methanol-induced HBsAg production, the time-dependent changes in the yeast proteome and ultrastructural cell morphology were analyzed during the production process. Results The shift from growth on glycerol to growth and HBsAg production on methanol was accompanied by a drastic change in the yeast proteome. In particular, enzymes from the methanol dissimilation pathway started to dominate the proteome while enzymes from the methanol assimilation pathway, e.g. the transketolase DAS1, increased only moderately. The majority of methanol was metabolized via the energy generating dissimilatory pathway leading to a corresponding increase in mitochondrial size and numbers. The methanol-metabolism related generation of reactive oxygen species induced a pronounced oxidative stress response (e.g. strong increase of the peroxiredoxin PMP20). Moreover, the accumulation of HBsAg in the ER resulted in the induction of the unfolded protein response (e.g. strong increase of the ER-resident disulfide isomerase, PDI) and the ER associated degradation (ERAD) pathway (e.g. increase of two cytosolic chaperones and members of the AAA ATPase superfamily) indicating that potential degradation of HBsAg could

  6. First principles-based adsorption comparison of group IV elements (C, Si, Ge, and Sn) on Au(111)/Ag(111) surface

    International Nuclear Information System (INIS)

    Chakraborty, Sudip; Rajesh, Ch.

    2012-01-01

    We have reported a first-principle investigation of the structural properties of monomer and dimer for group IV elements (C, Si, Ge, and Sn) adsorbed on the Au(111) and Ag(111) surfaces. The calculations were performed by means of a plane wave based pseudopotential method under the framework of density functional theory. The results reveal the preference of adatom to be adsorbed on the hexagonal closed packed site of the metal (111) surfaces with strong binding energy. The structures introduce interlayer forces in the adsorbate. The strong bonding with the surface atoms is a result of p–d hybridization. The adsorption energy follows a sequence as one goes down in the group IV elements which imply that the interaction of the group IV elements with Au/Ag is decreasing as the atomic number increases.

  7. Adsorbate-induced facetting reconstruction and self-organized domain patterning of vicinal Ag(111) surfaces; Adsorbatinduzierte richtungsabhaengige Facettierung und selbstorganisierte Domaenen-Musterbildung auf vizinalen Ag(111)-Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Stefan

    2007-02-05

    This thesis investigates structural aspects of adsorbate-induced facetting of vicinal Ag(111) surfaces. It is mainly based on scanning tunneling microscope (STM) and low energy electron diffraction (LEED) experiments performed under UHV conditions. The planar dye-molecule perylene-3,4,9,10-tetracarboxilicacid-dianhydride (PTCDA) adsorbs preferentially at the step edges of the 8.5 Ag(111) vicinal surfaces used in the experiments. It causes a facetting reconstruction by the formation of (111) terraces and facets with a high step density. Moreover, two distinct preferential inclinations of facets were observed, which can only be explained by the selective influence of the adsorbate superstructure. In terms of thermodynamics, the facetting reconstruction can be described as an orientational phase separation, adapted to the constraints of planar surfaces. This concept is capable of explaining the local facetting phenomena. The formalism used predicts an important role of nucleation kinetics. This aspect is taken into account by introducing an additional phase of mobile molecules (2D molecular gas), which cannot be measured directly. Furthermore, strong arguments for the appearance of a critical island size for the PTCDA/ Ag(111) superstructure were found. This work presents structural information of all stable superstructures of PTCDA on vicinal Ag(111) surfaces. Altogether 16 such superstructures were found, 3 of which had been observed and published before. Density and commensurability were found to systematically depend on the step-structure. The two preferred inclinations of facets are related to two characteristic types of domain boundaries of the herringbone superstructure to the adjacent (111)-terrace. On the (111) terraces, small islands of metastable superstructures were found. Facets and (111) terraces form a regular grating-like domain pattern with a variable structural width of 5 to 75 nm. STM measurements show direct evidence for a long-range interaction

  8. New amperometric and potentiometric immunosensors based on gold nanoparticles/tris(2,2'-bipyridyl)cobalt(III) multilayer films for hepatitis B surface antigen determinations.

    Science.gov (United States)

    Tang, Dianping; Yuan, Ruo; Chai, Yaqin; Fu, Yingzi; Dai, Jianyuan; Liu, Yan; Zhong, Xia

    2005-10-15

    Two generic, fast, sensitive and novel electrochemical immunosensors have been developed. Initially, a layer of plasma-polymerized Nafion film (PPF) was deposited on the platinum electrode surface, then positively charged tris(2,2'-bipyridyl)cobalt(III) (Co(bpy)(3)(3+)) and negatively charged gold nanoparticles were assembled on the PPF-modified Pt electrode by layer-by-layer technique. Finally, hepatitis B surface antibody (HBsAb) was electrostatically adsorbed on the gold nanoparticles surface. Electrochemical behavior of the {Au/Co(bpy)(3)(3+)}(n) multilayer film-modified electrodes was studied. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS) were adopted to monitor the regular growth of the multilayer films. The performance and factors influencing the performance of the resulting immunosensors were studied in detail. The multilayer film-modified immunosensor was used for hepatitis B surface antigen (HBsAg) determination via the amperometric and potentiometric immunosensor systems, and both systems provided the same linear ranges from 0.05 to 4.5 microg/mL with different detection limits for the amperometric system 0.005 microg/mL and for the potentiometric system 0.015 microg/mL. The immunosensors were used to analyse HBsAg in human serum samples. Analytical results of clinical samples show that the developed immunoassay is comparable with the enzyme-linked immunosorbent assays (ELISAs) method, implying a promising alternative approach for detecting HBsAg in the clinical diagnosis. In addition, the multilayer films also showed better stability for 1 month at least.

  9. Diamond like carbon Ag nanocomposites as a control measure against Campylobacter jejuni and Listeria monocytogenes on food preparation surfaces

    DEFF Research Database (Denmark)

    Zakarienė, Gintarė; Novoslavskij, Aleksandr; Meškinis, Šarūnas

    2018-01-01

    on selective agars and quantitative real-time PCR (qPCR) including staining with propidium monoazide (PMA). It was determined, that DLC:Ag film was the most efficient coating in the reduction of C. jejuni and L. monocytogenes numbers. Culture-based enumeration revealed that C. jejuni numbers were reduced...... by an average of 4.06 log10CFU/ml after 15 min and 3.61 log10CFU/ml after 30 min on DLC:Ag coated silicon wafers in comparison to control samples (P ≤ 0.05). L. monocytogenes was not detected on DLC:Ag samples after 24 h of exposure (P ≤ 0.05). PMA-qPCR showed that C. jejuni and L. monocytogenes affected by DLC......The effect of thin (5 nm) and thick (40 nm) silver layers and diamond like carbon nanocomposites with embedded Ag nanoparticles (DLC:Ag) against two reference strains of C. jejuni NCTC 11168 and L. monocytogenes ATCC 7644 were evaluated in this study. DLC:Ag film contained 22 at.% Ag. Silver...

  10. Hepatitis B surface antibodies in medical students from a public university in Puebla, Mexico.

    Science.gov (United States)

    Cárdenas-Perea, María Elena; Gómez-Conde, Eduardo; Santos-López, Gerardo; Pérez-Contreras, Irma; Díaz-Orea, María Alicia; Gándara-Ramírez, José Luís; Cruz Y López, Othón Rafael; Márquez-Domínguez, Luis; Sosa-Jurado, Francisca

    2016-07-02

    Although preventable with vaccination, Hepatitis B virus (HBV) infection is a major health concern, with ∼400 million people at risk of developing the chronic form of the disease worldwide. The anti-HBV vaccine consists of a recombinant HBV surface antigen (HBsAg), which induces specific anti-HBs antibodies and confers 95% protection for >20 y. The aim of the present study was to analyze the response to HBV vaccination by measuring anti-HBs antibodies in serum samples from medical students of a public university in Puebla, Mexico. HBV infection markers HBsAg and anti-HBs, were also determined. A total of 201 students were included and vaccination coverage was found at 54%. Overall seropositivity for HBsAg, anti-HBc and anti-HBs determined by ELISA was 0.5%, 1.0% and 47%, respectively. Protective levels of anti-HBs >10 mIU/mL were found in 93.2% of subjects vaccinated with 2 or 3 doses and in 40% of those vaccinated with a single dose; while only 4.8% of unvaccinated subjects were anti-HBs positive. The response to the HBV vaccine was different in each participant, despite similar vaccination scheme. A history of blood transfusion/organ transplant or more than 2 sexual partners was significantly associated with anti-HBc positivity, OR = 399 (p = 0.010) and OR = 19.9 (p = 0.044), respectively. HBV immunization coverage was low in our sample compared with reports from countries with similar HBV prevalence, but anti-HBs in vaccinated individuals were in the expected range. It is important to promote HBV vaccination and awareness among medical students, due to their exposure risk.

  11. PRISM hepatitis B surface antigen detection of hepatits B virus minipool nucleic acid testing yield samples.

    Science.gov (United States)

    Linauts, Sandy; Saldanha, John; Strong, D Michael

    2008-07-01

    Hepatitis B virus (HBV) residual risk has been estimated at 1:63,000-1:205,000 and introduction of more sensitive serological tests and nucleic acid testing (NAT) would reduce that risk. Sensitivity of the recently licensed Abbott PRISM hepatitis B surface antigen (HBsAg) CLIA and minipool (MP) HBV NAT has been described as comparable and thus the need for HBV NAT has not been compelling. In this study, eight samples identified as yield samples with MP HBV NAT were tested using the PRISM test. Seven samples were identified using the Roche COBAS AmpliScreen HBV test and one additional sample was obtained from the clinical trial for the Roche cobas TaqScreen MPX test. Each of these samples was reactive by MP HBV NAT and nonreactive for HBsAg using one of three licensed enzyme immunoassay (EIA) tests. After licensure of the PRISM HBsAg, aliquots were tested with this assay, and DNA quantitation and genotyping were repeated where sample volume permitted. Three samples (2000, 2300, and 61,000 copies/mL) produced reactive results with PRISM. Four samples with viral loads less than 300 copies per mL produced nonreactive results. One sample, originally quantitated at 37,000 copies per mL (but 3850 copies/mL in repeat testing) was also nonreactive by PRISM. Genotyping of this sample indicated a type C genotype with no mutations. Adding serological sensitivity of PRISM CLIA reduced the NAT yield from the original 1: 385,555 to 1:610,488. However, MP HBV NAT still provides additional sensitivity over CLIA, even for a donation with a viral load of almost 4000 copies per mL.

  12. Hepatitis B surface antibodies in medical students from a public university in Puebla, Mexico

    Science.gov (United States)

    Cárdenas-Perea, María Elena; Gómez-Conde, Eduardo; Santos-López, Gerardo; Pérez-Contreras, Irma; Díaz-Orea, María Alicia; Gándara-Ramírez, José Luís; Cruz y López, Othón Rafael; Márquez-Domínguez, Luis; Sosa-Jurado, Francisca

    2016-01-01

    ABSTRACT Although preventable with vaccination, Hepatitis B virus (HBV) infection is a major health concern, with ∼400 million people at risk of developing the chronic form of the disease worldwide. The anti-HBV vaccine consists of a recombinant HBV surface antigen (HBsAg), which induces specific anti-HBs antibodies and confers 95% protection for >20 y. The aim of the present study was to analyze the response to HBV vaccination by measuring anti-HBs antibodies in serum samples from medical students of a public university in Puebla, Mexico. HBV infection markers HBsAg and anti-HBs, were also determined. A total of 201 students were included and vaccination coverage was found at 54%. Overall seropositivity for HBsAg, anti-HBc and anti-HBs determined by ELISA was 0.5%, 1.0% and 47%, respectively. Protective levels of anti-HBs >10 mIU/mL were found in 93.2% of subjects vaccinated with 2 or 3 doses and in 40% of those vaccinated with a single dose; while only 4.8% of unvaccinated subjects were anti-HBs positive. The response to the HBV vaccine was different in each participant, despite similar vaccination scheme. A history of blood transfusion/organ transplant or more than 2 sexual partners was significantly associated with anti-HBc positivity, OR = 399 (p = 0.010) and OR = 19.9 (p = 0.044), respectively. HBV immunization coverage was low in our sample compared with reports from countries with similar HBV prevalence, but anti-HBs in vaccinated individuals were in the expected range. It is important to promote HBV vaccination and awareness among medical students, due to their exposure risk. PMID:27171749

  13. Combined use of vancomycin-modified Ag-coated magnetic nanoparticles and secondary enhanced nanoparticles for rapid surface-enhanced Raman scattering detection of bacteria.

    Science.gov (United States)

    Wang, Chongwen; Gu, Bing; Liu, Qiqi; Pang, Yuanfeng; Xiao, Rui; Wang, Shengqi

    2018-01-01

    Pathogenic bacteria have always been a significant threat to human health. The detection of pathogens needs to be rapid, accurate, and convenient. We present a sensitive surface-enhanced Raman scattering (SERS) biosensor based on the combination of vancomycin-modified Ag-coated magnetic nanoparticles (Fe 3 O 4 @Ag-Van MNPs) and Au@Ag nanoparticles (NPs) that can effectively capture and discriminate bacterial pathogens from solution. The high-performance Fe 3 O 4 @Ag MNPs were modified with vancomycin and used as bacteria capturer for magnetic separation and enrichment. The modified MNPS were found to exhibit strong affinity with a broad range of Gram-positive and Gram-negative bacteria. After separating and rinsing bacteria, Fe 3 O 4 @Ag-Van MNPs and Au@Ag NPs were synergistically used to construct a very large number of hot spots on bacteria cells, leading to ultrasensitive SERS detection. The dominant merits of our dual enhanced strategy included high bacterial-capture efficiency (>65%) within a wide pH range (pH 3.0-11.0), a short assay time (<30 min), and a low detection limit (5×10 2 cells/mL). Moreover, the spiked tests show that this method is still valid in milk and blood samples. Owing to these capabilities, the combined system enabled the sensitive and specific discrimination of different pathogens in complex solution, as verified by its detection of Gram-positive bacterium Escherichia coli , Gram-positive bacterium Staphylococcus aureus , and methicillin-resistant S. aureus . This method has great potential for field applications in food safety, environmental monitoring, and infectious disease diagnosis.

  14. Synthesis of Ball-Like Ag Nanorod Aggregates for Surface-Enhanced Raman Scattering and Catalytic Reduction.

    Science.gov (United States)

    Zhang, Wenjing; Cai, Yin; Qian, Rui; Zhao, Bo; Zhu, Peizhi

    2016-05-25

    In this work, ball-like Ag nanorod aggregates have been synthesized via a simple seed-mediated method. These Ag mesostructures were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and X-ray diffraction (XRD). Adding a certain amount of polyvinyl pyrrolidone (PVP) can prolong its coagulation time. These Ag nanorod aggregates exhibit effective SERS effect, evaluated by Rhodamine 6G (R6G) and doxorubicin (DOX) as probe molecules. The limit of detection (LOD) for R6G and DOX are as low as 5 × 10 -9 M and 5 × 10 -6 M, respectively. Moreover, these Ag nanorod aggregates were found to be potential catalysts for the reduction of 4-nitrophenol (4-NP) in the presence of NaBH₄.

  15. Synthesis of Ball-Like Ag Nanorod Aggregates for Surface-Enhanced Raman Scattering and Catalytic Reduction

    Directory of Open Access Journals (Sweden)

    Wenjing Zhang

    2016-05-01

    Full Text Available In this work, ball-like Ag nanorod aggregates have been synthesized via a simple seed-mediated method. These Ag mesostructures were characterized by scanning electron microscope (SEM, transmission electron microscopy (TEM, ultraviolet-visible spectroscopy (UV-Vis, and X-ray diffraction (XRD. Adding a certain amount of polyvinyl pyrrolidone (PVP can prolong its coagulation time. These Ag nanorod aggregates exhibit effective SERS effect, evaluated by Rhodamine 6G (R6G and doxorubicin (DOX as probe molecules. The limit of detection (LOD for R6G and DOX are as low as 5 × 10−9 M and 5 × 10−6 M, respectively. Moreover, these Ag nanorod aggregates were found to be potential catalysts for the reduction of 4-nitrophenol (4-NP in the presence of NaBH4.

  16. HCV and HBV coexist in HBsAg-negative patients with HCV viremia; possibility of coinfection in these patients must be considered in HBV-high endemic area

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Soon [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1998-01-01

    Hepatocellular carcinoma (HCC) is one of the most common cancers and is highly associated with HBV infection in Korea. It has been suggested that HCV core protein may impair the polymerase activity of HBV in vitro, potentially lowering HBV titre in coinfected patients. The aim of this study was to confirm the coexistence of HBV viremia in HCV infected patients HCC who have apparent HBsAg seronegativity. The serological profiles of HBV and HCV in 616 patients with HCC were analysed and coinfection rate of HBV and HCV investigated. Sera were obtained from 16 patients who were both anti-HCV and HCV RNA positive but HbsAg negative, and tested for HBV BY PCR. As a control group, sera were obtained from 15 patients with HCC and 30 non-A abd non-B chronic hepatitis patients without HCC; both were anti-HCV, HCV-RNA, and HBsAg negative and tested for HBV PCR. Of 616 patients with HCC, 450 (73.1 %) had current HBV infection, 48 (7.8 %) had anti-HCV antibodies, and nine (1.5 %) had viral markers of both HCV abd HBV by serological profiles. Of 27 the patients with HCV viremia and HBsAg seronegativity, 14 (51.9 %) showed HBV viremia by PCR. In contrast, of the 75 patients in the control group who were both HCV PCR negative and HBsAg negative, five (11.1 %) showed HBV viremia by PCR. The PCR for HBV revealed coexistent HBV viremia in HCV viremia patients, despite HBsAg negativity by EIA. In HBV-endemic areas, the possibility of coinfection of HBV in HBsAg-negative patients with HCV viremia should be considered and molecular analysis for HBV-DNA performed. (author). 18 refs., 4 tabs.

  17. Prevalence of Hepatitis B Cab with or Without Anti Hbsab in Hbsag Seronegative Blood Donors

    Directory of Open Access Journals (Sweden)

    H Salman Roughani

    2005-01-01

    Full Text Available Introduction: There are multiple reports of Acute Hepatitis B after blood transfusion inspite of good screening for Hepatitis B before transfusion. Therefore, occult hepatitis B is a serious concern for Blood transfusion. There is a lot of evidence that positive HBCAb in seronegative HBSAg blood donors is associated with occult Hepatitis B. Aim: Evaluation of the prevalence of HBCAb in seronegative HBSAg blood donors. Method: In a cross sectional descriptive study, we evaluated the serum of 1230 Blood donors for HBCAb, HCVAb and Aminotranferase levels. HBSAg or AntiHIV Ab positive cases were excluded from the study. Detection of Anti HBSAb was done in HBCAb positive patients and liver biopsy was performed in all HCVAb positive cases. Results: 15.1% of blood donors were positive for HBCAb and 51.6% of them had Anti HBSAb. Aminotranferase levels were normal in all people who were positive for HBCAb ,but about 50% of HCVAb positive persons had elevated aminotransferase levels and liver biopsy of all these patients showed inflammation Conclusion: Prevalence of HBCAb is high in our seronegative HBSAg Blood donors and biomolecular studies such as PCR for HBV DNA is indicated in HBCAb positive people, especially in people with isolated HBCAb .

  18. A large-scale superhydrophobic surface-enhanced Raman scattering (SERS) platform fabricated via capillary force lithography and assembly of Ag nanocubes for ultratrace molecular sensing.

    Science.gov (United States)

    Tan, Joel Ming Rui; Ruan, Justina Jiexin; Lee, Hiang Kwee; Phang, In Yee; Ling, Xing Yi

    2014-12-28

    An analytical platform with an ultratrace detection limit in the atto-molar (aM) concentration range is vital for forensic, industrial and environmental sectors that handle scarce/highly toxic samples. Superhydrophobic surface-enhanced Raman scattering (SERS) platforms serve as ideal platforms to enhance detection sensitivity by reducing the random spreading of aqueous solution. However, the fabrication of superhydrophobic SERS platforms is generally limited due to the use of sophisticated and expensive protocols and/or suffers structural and signal inconsistency. Herein, we demonstrate a high-throughput fabrication of a stable and uniform superhydrophobic SERS platform for ultratrace molecular sensing. Large-area box-like micropatterns of the polymeric surface are first fabricated using capillary force lithography (CFL). Subsequently, plasmonic properties are incorporated into the patterned surfaces by decorating with Ag nanocubes using the Langmuir-Schaefer technique. To create a stable superhydrophobic SERS platform, an additional 25 nm Ag film is coated over the Ag nanocube-decorated patterned template followed by chemical functionalization with perfluorodecanethiol. Our resulting superhydrophobic SERS platform demonstrates excellent water-repellency with a static contact angle of 165° ± 9° and a consequent analyte concentration factor of 59-fold, as compared to its hydrophilic counterpart. By combining the analyte concentration effect of superhydrophobic surfaces with the intense electromagnetic "hot spots" of Ag nanocubes, our superhydrophobic SERS platform achieves an ultra-low detection limit of 10(-17) M (10 aM) for rhodamine 6G using just 4 μL of analyte solutions, corresponding to an analytical SERS enhancement factor of 10(13). Our fabrication protocol demonstrates a simple, cost- and time-effective approach for the large-scale fabrication of a superhydrophobic SERS platform for ultratrace molecular detection.

  19. Prevalence and chemotherapy-induced reactivation of occult hepatitis B virus among hepatitis B surface antigen negative patients with diffuse large B-cell lymphoma: Significance of hepatitis B core antibodies screening

    International Nuclear Information System (INIS)

    Elbedewy, T.A.; Elashtokhy, H.A.; Rabee, E.S.; Kheder, G.E.

    2015-01-01

    Background: Occult hepatitis B infection (OBI) is characterized by negative hepatitis B surface antigen (HBsAg) and detectable hepatitis B virus (HBV)-DNA in the liver and/or serum, with or without hepatitis B core antibody (anti-HBc). Anti-HBc is the most sensitive marker of previous HBV. HBV reactivation in patients under immunosuppressive treatment is life-threatening, occurring in both overt and occult HBV especially in hematological malignancies. Aim of the work: To evaluate the prevalence and chemotherapy-induced reactivation of OBI among hepatitis B surface antigen negative patients with diffuse large B-cell lymphoma (DLBCL) patients and to determine the significance of anti-HBc screening among this group of patients before receiving chemotherapy. Patients and methods: This cross-sectional study included 72 DLBCL patients negative for HBsAg, HBsAb and hepatitis C virus antibodies (anti-HCV). Patients were subjected to investigations including anti-HBc. All patients underwent alanine transaminase (ALT) monitoring before each cycle of chemotherapy and monthly for 12 months after the end of chemotherapy. Patients with suspected OBI were tested for HBV-DNA using real-time polymerase chain reaction (PCR). Results: Anti-HBc was detected in 10 of 72 HBsAg negative sera (13.89%) (95% confidence interval 6.9-22.2%). Five of the 10 anti-HBc positive patients in this study had OBI reactivation. Conclusion: The study concluded that anti-HBc screening is mandatory before chemotherapy. HBsAg-negative/anti-HBc-positive patients should be closely observed for signs of HBV reactivation through the regular monitoring of ALT. Prophylaxis lamivudine is recommended for anti-HBc positive patients before chemotherapy.

  20. Au-Ag Core-Shell Nanospheres for Surface-Enhanced Raman Scattering Detection of Sudan I and Sudan II in Chili Powder

    Directory of Open Access Journals (Sweden)

    Lu Pei

    2015-01-01

    Full Text Available Au-Ag core-shell (Au@Ag bimetallic nanospheres synthesized by a facile seed-growth method are proposed as a substrate for surface-enhanced Raman spectroscopy (SERS to detect azo-group dyes including Sudan I and Sudan II. Au@Ag nanospheres with a series of particle sizes (diameter: 30–120 nm and silver shell thicknesses (6–51 nm were synthesized and compared for their morphological and optical properties to obtain optimum enhancement effect. Normal Raman, SERS, infrared, and ultraviolet-visible were used to investigate the optical absorption properties of Sudan I and Sudan II as well as the enhancement mechanism of Au@Ag substrates. The nanospheres with particle size of 73 ± 6 nm in diameter and silver layer of 27 ± 2 nm resulted in the highest enhancement effect and could be used to detect Sudan I and Sudan II standard solutions at levels as low as 0.4 and 0.1 mg/L, respectively. Moreover, Sudan I and Sudan II in chili powder could be detected at 0.6 and 0.4 mg/kg, respectively. Sudan I and Sudan II with similar structures in complicated food matrices could be distinguished through applying principal component analysis, indicating good selectivity of the SERS method for detection of banned additives in food stuffs at trace levels.

  1. Thermal cyclic test for Sn-4Ag-0.5Cu solders on high P Ni/Au and Ni/Pd/Au surface finishes

    Directory of Open Access Journals (Sweden)

    M.A. Azmah Hanim

    2015-12-01

    Full Text Available In electronic packaging, the reliability of the interconnection changes with the surface finish and the type of solders being used. Thermal cycling is one method of reliability assessment. In thermal cycling experiments, the strain state is simplified by soldering together regular shaped pieces of materials with different coefficients of thermal expansion and exposing the joint to repeated fluctuations of temperature within a certain range. Thus, this study focuses on the intermetallic evolution of Sn-4Ag-0.5Cu on Ni/Au and Ni/Pd/Au surface finishes with thermal cycling up to 1000 cycles with the range of temperature varying from 10 to 80 °C. Sandwich samples were prepared by placing solder balls of Sn-4Ag-0.5Cu between two substrates of two different surface finishes: Ni/Au and Ni/Pd/Au. Optical microscope and FESEM (Field emission scanning electron microscope were used to analyze the samples. From the study, it was observed that the intermetallic changes from (Cu, Ni6Sn5 to (Ni, Cu3Sn4 after 1000 thermal cycles for Ni/Au. These changes promote the formation of cracks at the solder joint because of the different mechanical properties between Ni-Sn based intermetallic and Cu-Sn intermetallics. However, for the Ni/Pd/Au surface finishes, no cracks formed after thermal cycling up to 1000 cycles. This shows that the reliability of the solder joint is higher for Ni/Pd/Au surface finishes in this experiment. Based on these results, it can be concluded that the reliability of the Ni/Pd/Au surface finishes with Sn-4Ag-0.5Cu solders is higher within the given condition of this research.

  2. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    Science.gov (United States)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  3. Green synthesis, characterization of Au–Ag core–shell nanoparticles using gripe water and their applications in nonlinear optics and surface enhanced Raman studies

    International Nuclear Information System (INIS)

    Kirubha, E; Palanisamy, P K

    2014-01-01

    In recent years there has been excessive progress in the ‘green’ chemistry approach for the synthesis of gold and silver nanoparticles. Bimetallic nanoparticles have gained special significance due to their unique tunable optical properties. Herein we report a facile one-pot, eco-friendly synthesis of Au–Ag bimetallic core–shell nanoparticles using gripe water as reducing as well as stabilizing agent. The as-synthesized Au–Ag nanoparticles are characterized using UV–Vis spectroscopy to determine the surface plasmon resonance, and using transmission electron microscopy to study the morphology and the particle size. The optical nonlinearity of the bimetallic nanoparticles investigated by z-scan technique using femtosecond Ti:sapphire is in the order of 10 9 . The nonlinear optical parameters such as the nonlinear refractive index n 2 , nonlinear absorption coefficient β and the third order nonlinear susceptibility χ 3 are measured for various wavelengths from 700 nm to 950 nm. The Au–Ag nanoparticles are also used in surface enhanced Raman spectroscopic studies to enhance the Raman signals of rhodamine 6G. (paper)

  4. Green synthesis, characterization of Au-Ag core-shell nanoparticles using gripe water and their applications in nonlinear optics and surface enhanced Raman studies

    Science.gov (United States)

    Kirubha, E.; Palanisamy, P. K.

    2014-12-01

    In recent years there has been excessive progress in the ‘green’ chemistry approach for the synthesis of gold and silver nanoparticles. Bimetallic nanoparticles have gained special significance due to their unique tunable optical properties. Herein we report a facile one-pot, eco-friendly synthesis of Au-Ag bimetallic core-shell nanoparticles using gripe water as reducing as well as stabilizing agent. The as-synthesized Au-Ag nanoparticles are characterized using UV-Vis spectroscopy to determine the surface plasmon resonance, and using transmission electron microscopy to study the morphology and the particle size. The optical nonlinearity of the bimetallic nanoparticles investigated by z-scan technique using femtosecond Ti:sapphire is in the order of 109. The nonlinear optical parameters such as the nonlinear refractive index n2, nonlinear absorption coefficient β and the third order nonlinear susceptibility χ3 are measured for various wavelengths from 700 nm to 950 nm. The Au-Ag nanoparticles are also used in surface enhanced Raman spectroscopic studies to enhance the Raman signals of rhodamine 6G.

  5. Ag doped TiO2 nanoparticles prepared by hydrothermal method and coating of the nanoparticles on the ceramic pellets for photocatalytic study: Surface properties and photoactivity

    Directory of Open Access Journals (Sweden)

    Oguzhan Avciata

    2018-02-01

    Full Text Available In this work, Ag doped nano TiO2 photocatalysts were synthesized in powder form by hydrothermal method at 180 ºC in 120 min using different reduction agents. The synthesized powders were characterized by powder X-ray diffraction (XRD, Energydispersive X-ray spectroscopy (EDS, Surface area measurements (BET, Transmission electron microscopy (TEM and scanning electron microscopy (SEM analyses. The effect of reduction agents on the morphological properties of Ag doped nano TiO2 has been studied. We have been observed that the use of different reduction agents affects the particle size and surface area. Ag doped nano TiO2 photocatalysts were coated to the ceramic pellets by dip coating technique for photocatalytic study. Photocatalytic properties of the synthesized powder were examined in a circulating aquarium filled with indigo blue (IB solution under UV irradiation. Periodical UV spectrophotometric analysis showed that indigo blue (IB has been degraded and its concentration has decreased under UV irradiation by time.

  6. Prevention of Post Transfusion Hepatitis Employing Sensitive Assay for Hepatitis B Surface Antigen Screening(Topics in Transfusion Medicine 1990 : Autologous Transfusion and Post-Transfusion Hepatitis)

    OpenAIRE

    小島, 秀男; 大竹, 幸子; 富樫, 和枝; 石口, 重子; 山田, 恵子; 品田, 章二; Kojima, Hideo; Ohtake, Sachiko; Togashi, Kazue; Ishiguchi, Shigeko; Yamada, Keiko; Shinada, Shoji

    1990-01-01

    Post transfusion Hepatitis (PTH) is one of serious side effects and some times lead to fulminant hepatic failure in case transfused blood contain very low level (under the sensitivity of usual screening method) of hepatitis B virus (HBV). Redcross blood center and blood transfusion devision of our hospital have been employed reverse passive hemmaglutination method (RPHA) for HBsAg screening. Authors employed EIA for sensitive HBsAg test system and compared with RPHA method. Of 2,255 sera from...

  7. One-pot synthesis of Ag-SiO2-Ag sandwich nanostructures

    International Nuclear Information System (INIS)

    Li Chaorong; Mei Jie; Li Shuwen; Lu Nianpeng; Wang Lina; Chen Benyong; Dong Wenjun

    2010-01-01

    Ag-SiO 2 -Ag sandwich nanostructures were prepared by a facile one-pot synthesis method. The Ag core, SiO 2 shell and Ag nanoparticle shell were all synthesized with polyvinylpyrrolidone, catalysed by ammonia, in the one-pot reaction. The polyvinylpyrrolidone, acting as a smart reducing agent, reduced the Ag + to Ag cores and Ag shells separately. Furthermore, the polyvinylpyrrolidone served as a protective agent to prevent the silver cores from aggregating. The SiO 2 shell and outer layer Ag nanoparticles were obtained when tetraethyl orthosilicate and ammonia were added to the silver core solution. Ammonia, acting as the catalyst, accelerated the hydrolysis of the tetraethyl orthosilicate to SiO 2 , which coated the silver cores. Furthermore, Ag(NH 3 ) 2 + ions were formed when aqueous ammonia was added to the solution, which increased the reduction capability. Then the polyvinylpyrrolidone reduced the Ag(NH 3 ) 2 + ions to small Ag nanoparticles on the surface of the Ag-SiO 2 and formed Ag-SiO 2 -Ag sandwich structures with a standard deviation of less than 4%. This structure effectively prevented the Ag nanoparticles on the silica surface from aggregating. Furthermore, the Ag-SiO 2 -Ag sandwich structures showed good catalysis properties due to the large surface area/volume value and activity of surface atoms of Ag particles.

  8. Accumulation of radioactive corrosion products on steel surfaces of VVER type nuclear reactors. I. 110mAg

    CSIR Research Space (South Africa)

    Hirschberg, G

    1999-03-01

    Full Text Available Formation, presence and deposition of corrosion product radionuclides (such as 60Co, 51Cr, 54Mn, 59Fe and/or 110mAg) in the primary circuits of water-cooled nuclear reactors (PWRs) throw many obstacles in the way of normal operation. During...

  9. Effect of 100 MeV Ag{sup +7} ion irradiation on the bulk and surface magnetic properties of Co–Fe–Si thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hysen, T., E-mail: hysenthomas@gmail.com [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India); Department of Physics, Christian College, Chengannur, Kerala 689 122 (India); Geetha, P. [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India); Al-Harthi, Salim; Al-Omari, I.A. [Department of Physics, College of Science, Sultan Qaboos University, Al Khod 123 (Oman); Lisha, R. [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India); Ramanujan, R.V. [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639 798 (Singapore); Sakthikumar, D. [Graduate School of Interdisciplinary New Science, Toyo University, Kawagoe (Japan); Avasthi, D.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Anantharaman, M.R., E-mail: mra@cusat.ac.in [Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala (India)

    2014-12-15

    Thin films of Co–Fe–Si were vacuum evaporated on pre-cleaned float glass substrates employing thermal evaporation. The films were subsequently irradiated with 100 MeV Ag{sup +7} ions at fluences of 1×10{sup 11}, 1×10{sup 12} and 1×10{sup 13} ions/cm{sup 2}. The pristine and irradiated samples were subjected to surface analysis using Atomic Force Microscopy (AFM), Vibrating Sample Magnetometry (VSM) and Magneto Optic Kerr Effect (MOKE) measurements. The as deposited film has a root mean square roughness (Rq) of 8.9 nm and an average roughness of (Ra) 5.6 nm. Irradiation of the as deposited films with 100 MeV Ag{sup 7+} ions modifies the surface morphology. Irradiating with ions at fluences of 1×10{sup 11} ions/cm{sup 2} smoothens the mesoscopic hill-like structures, and then, at 1×10{sup 12} ions/cm{sup 2} new surface structures are created. When the fluence is further increased to 1×10{sup 13} ions/cm{sup 2} an increase in the surface roughness is observed. The MOKE loop of as prepared film indicated a squareness ratio of 0.62. As the film is irradiated with fluences of 1×10{sup 11} ions/cm{sup 2}, 1×10{sup 12} ions/cm{sup 2} and 1×10{sup 13} ions/cm{sup 2} the squareness ratio changes to 0.76, 0.8 and 0.86 respectively. This enhancement in squareness ratio towards 1 is a typical feature when the exchange interaction starts to dominates the inherent anisotropies in the system. The variation in surface magnetisation is explained based on the variations in surface roughness with swift heavy ion (SHI) irradiation. - Highlights: • We have irradiated thermally evaporated Co–Fe–Si thin films on glass substrate with 100 MeV Ag{sup +7} ions using the 15 UD Pelletron Accelerator at IUAC, New Delhi, India. • Surface morphology and magnetic characteristics of the films can be altered with ion irradiation. • It was observed that the variation in surface magnetic properties correlates well with the changes in surface morphology, further reiterating the

  10. Analyzing relationships between surface perturbations and local chemical reactivity of metal sites: Alkali promotion of O2 dissociation on Ag(111)

    Science.gov (United States)

    Xin, Hongliang; Linic, Suljo

    2016-06-01

    Many commercial heterogeneous catalysts are complex structures that contain metal active sites promoted by multiple additives. Developing fundamental understanding about the impact of these perturbations on the local surface reactivity is crucial for catalyst development and optimization. In this contribution, we develop a general framework for identifying underlying mechanisms that control the changes in the surface reactivity of a metal site (more specifically the adsorbate-surface interactions) upon a perturbation in the local environment. This framework allows us to interpret fairly complex interactions on metal surfaces in terms of specific, physically transparent contributions that can be evaluated independently of each other. We use Cs-promoted dissociation of O2 as an example to illustrate our approach. We concluded that the Cs adsorbate affects the outcome of the chemical reaction through a strong alkali-induced electric field interacting with the static dipole moment of the O2/Ag(111) system.

  11. Adhesion profile and differentiation capacity of human adipose tissue derived mesenchymal stem cells grown on metal ion (Zn, Ag and Cu) doped hydroxyapatite nano-coated surfaces.

    Science.gov (United States)

    Bostancioglu, R Beklem; Gurbuz, Mevlut; Akyurekli, Ayse Gul; Dogan, Aydin; Koparal, A Savas; Koparal, A Tansu

    2017-07-01

    Accelerated Mesenchymal Stem Cells (MSCs) condensation and robust MSC-matrix and MSC-MSC interactions on nano-surfaces may provide critical factors contributing to such events, likely through the orchestrated signal cascades and cellular events modulated by the extracellular matrix. In this study, human adipose tissue derived mesenchymal stem cells (hMSC)', were grown on metal ion (Zn, Ag and Cu) doped hydroxyapatite (HAP) nano-coated surfaces. These metal ions are known to have different chemical and surface properties; therefore we investigated their respective contributions to cell viability, cellular behavior, osteogenic differentiation capacity and substrate-cell interaction. Nano-powders were produced using a wet chemical process. Air spray deposition was used to accumulate the metal ion doped HAP films on a glass substrate. Cell viability was determined by MTT, LDH and DNA quantitation methods Osteogenic differentiation capacity of hMSCs was analyzed with Alizarin Red Staining and Alkaline Phosphatase Specific Activity. Adhesion of the hMSCs and the effect of cell adhesion on biomaterial biocompatibility were explored through cell adhesion assay, immunofluorescence staining for vinculin and f-actin cytoskeleton components, SEM and microarray including 84 known extracellular matrix proteins and cell adhesion pathway genes, since, adhesion is the first step for good biocompability. The results demonstrate that the viability and osteogenic differentiation of the hMSCs (in growth media without osteogenic stimulation) and cell adhesion capability are higher on nanocoated surfaces that include Zn, Ag and/or Cu metal ions than commercial HAP. These results reveal that Zn, Ag and Cu metal ions contribute to the biocompatibility of exogenous material. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Combining density functional and incremental post-Hartree-Fock approaches for van der Waals dominated adsorbate-surface interactions: Ag2/graphene

    International Nuclear Information System (INIS)

    Lara-Castells, María Pilar de; Mitrushchenkov, Alexander O.; Stoll, Hermann

    2015-01-01

    A combined density functional (DFT) and incremental post-Hartree-Fock (post-HF) approach, proven earlier to calculate He-surface potential energy surfaces [de Lara-Castells et al., J. Chem. Phys. 141, 151102 (2014)], is applied to describe the van der Waals dominated Ag 2 /graphene interaction. It extends the dispersionless density functional theory developed by Pernal et al. [Phys. Rev. Lett. 103, 263201 (2009)] by including periodic boundary conditions while the dispersion is parametrized via the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)]. Starting with the elementary cluster unit of the target surface (benzene), continuing through the realistic cluster model (coronene), and ending with the periodic model of the extended system, modern ab initio methodologies for intermolecular interactions as well as state-of-the-art van der Waals-corrected density functional-based approaches are put together both to assess the accuracy of the composite scheme and to better characterize the Ag 2 /graphene interaction. The present work illustrates how the combination of DFT and post-HF perspectives may be efficient to design simple and reliable ab initio-based schemes in extended systems for surface science applications

  13. Combining density functional and incremental post-Hartree-Fock approaches for van der Waals dominated adsorbate-surface interactions: Ag2/graphene.

    Science.gov (United States)

    de Lara-Castells, María Pilar; Mitrushchenkov, Alexander O; Stoll, Hermann

    2015-09-14

    A combined density functional (DFT) and incremental post-Hartree-Fock (post-HF) approach, proven earlier to calculate He-surface potential energy surfaces [de Lara-Castells et al., J. Chem. Phys. 141, 151102 (2014)], is applied to describe the van der Waals dominated Ag2/graphene interaction. It extends the dispersionless density functional theory developed by Pernal et al. [Phys. Rev. Lett. 103, 263201 (2009)] by including periodic boundary conditions while the dispersion is parametrized via the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)]. Starting with the elementary cluster unit of the target surface (benzene), continuing through the realistic cluster model (coronene), and ending with the periodic model of the extended system, modern ab initio methodologies for intermolecular interactions as well as state-of-the-art van der Waals-corrected density functional-based approaches are put together both to assess the accuracy of the composite scheme and to better characterize the Ag2/graphene interaction. The present work illustrates how the combination of DFT and post-HF perspectives may be efficient to design simple and reliable ab initio-based schemes in extended systems for surface science applications.

  14. Combining density functional and incremental post-Hartree-Fock approaches for van der Waals dominated adsorbate-surface interactions: Ag{sub 2}/graphene

    Energy Technology Data Exchange (ETDEWEB)

    Lara-Castells, María Pilar de, E-mail: Pilar.deLara.Castells@csic.es [Instituto de Física Fundamental (C.S.I.C.), Serrano 123, E-28006 Madrid (Spain); Mitrushchenkov, Alexander O. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Stoll, Hermann [Institut für Theoretische Chemie, Universität Stuttgart, D-70550 Stuttgart (Germany)

    2015-09-14

    A combined density functional (DFT) and incremental post-Hartree-Fock (post-HF) approach, proven earlier to calculate He-surface potential energy surfaces [de Lara-Castells et al., J. Chem. Phys. 141, 151102 (2014)], is applied to describe the van der Waals dominated Ag{sub 2}/graphene interaction. It extends the dispersionless density functional theory developed by Pernal et al. [Phys. Rev. Lett. 103, 263201 (2009)] by including periodic boundary conditions while the dispersion is parametrized via the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)]. Starting with the elementary cluster unit of the target surface (benzene), continuing through the realistic cluster model (coronene), and ending with the periodic model of the extended system, modern ab initio methodologies for intermolecular interactions as well as state-of-the-art van der Waals-corrected density functional-based approaches are put together both to assess the accuracy of the composite scheme and to better characterize the Ag{sub 2}/graphene interaction. The present work illustrates how the combination of DFT and post-HF perspectives may be efficient to design simple and reliable ab initio-based schemes in extended systems for surface science applications.

  15. Dissociation of N{sub 2}O on anatase TiO{sub 2} (001) surface – The effect of oxygen vacancy and presence of Ag cluster

    Energy Technology Data Exchange (ETDEWEB)

    Sowmiya, M.; Senthilkumar, K., E-mail: ksenthil@buc.edu.in

    2016-12-15

    Highlights: • This study elucidates the dissociation of N{sub 2}O on anatase TiO{sub 2} (001) surface. • N{sub 2}O is decomposed into N{sub 2} and O on reduced TiO{sub 2} even in the presence of Ag cluster. • Excess charge in reduced TiO{sub 2} surface is transferred to the adsorbed N{sub 2}O molecule. • The vibrational frequency analysis also performed to study the dissociation of N{sub 2}O. • Anatase TiO{sub 2} with oxygen vacancies is a suitable catalyst for decomposition of N{sub 2}O. - Abstract: The increase in concentration of nitrous oxide (N{sub 2}O) in the atmosphere is one of the major contributors to the greenhouse effect, ozone depletion and climate change. Therefore, it is important to decompose harmful N{sub 2}O molecule into harmless N{sub 2}. In the present work, we have studied the decomposition of N{sub 2}O on anatase TiO{sub 2} (001) surface using first principle calculations. The results indicates that the N{sub 2}O molecule is physisorbed on perfect TiO{sub 2} surface without any dissociation, and is dissociated into N{sub 2} and oxygen on the reduced TiO{sub 2} surface. In addition, it has been found that the interaction between N{sub 2}O and TiO{sub 2} is augmented by the presence of Ag cluster on anatase (001) surface. On the basis of Bader charge analysis and electron density difference plot, it has been found that the excess charge in the reduced anatase TiO{sub 2} (001) surface is transferred to the adsorbed N{sub 2}O molecule, which results the weakening of N–O bond of N{sub 2}O followed by the decomposition of N{sub 2}O into N{sub 2} and O. Vibrational frequency analysis also performed to confirm the decomposition of N{sub 2}O molecule. From the pathway for N{sub 2}O dissociation on reduced TiO{sub 2} and Ag/TiO{sub 2} surfaces, it has been observed that the dissociation reaction of N{sub 2}O on TiO{sub 2} surface is highly exothermic with activation energy barrier of 0.25 eV. The results presented in this work show that the

  16. Ag transport in CrN-Ag nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Mulligan, C.P. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); U.S. Army Armament Research Development and Engineering Center, Benet Laboratories, Watervliet, NY 12189 (United States); Papi, P.A. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Gall, D., E-mail: galld@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2012-09-01

    2-{mu}m-thick CrN-Ag composite coatings containing 22 at.% Ag were deposited on Si(001) by reactive co-sputtering at T{sub s} = 300, 400, and 500 Degree-Sign C. Subsequent vacuum annealing at T{sub a} = 425, 525, and 625 Degree-Sign C causes Ag transport to the surface. Auger electron spectroscopy and plan-view microscopy are used to quantify the Ag transport to the surface, which increases strongly with increasing {Delta}T = T{sub a} - T{sub s}. Compositional depth profiles and cross-sectional microscopy show that annealing causes a negligible Ag gradient through the composite layer, suggesting that the Ag transport is detachment-limited as opposed to diffusion-limited. Statistical analyses of Ag aggregate size-distributions within the matrix show that large aggregates ({>=} 50 nm) are unaffected by annealing, while the Ag in a large fraction of small aggregates (< 50 nm) moves to the surface, leaving behind 10-50 nm wide voids in the annealed composite. This indicates that the Ag from the smaller grains, with a higher chemical potential and thus a higher detachment rate, is transferred to the large grains on the surface which are 200-1000 nm wide. - Highlights: Black-Right-Pointing-Pointer CrN-Ag coatings were deposited at T{sub s} = 300-500 Degree-Sign C and annealed at T{sub a} = 425-625 Degree-Sign C. Black-Right-Pointing-Pointer Ag diffuses from aggregates in the coating to the surface, if T{sub a} > T{sub s}. Black-Right-Pointing-Pointer During annealing, aggregates < 50 nm become voids, those > 50 nm are unaffected. Black-Right-Pointing-Pointer The Ag transport is detachment rather than diffusion limited.

  17. Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-to-metal resin-bonded fixed partial dentures.

    Science.gov (United States)

    Chen, Xiwen; Zhang, Yixin; Zhou, Jinru; Chen, Chenfeng; Zhu, Zhimin; Li, Lei

    2018-02-01

    The aim of this study was to investigate the adhesive property of palladium-silver alloy (Pd-Ag) and the simulated clinical performance of Pd-Ag porcelain-fused-to-metal (PFM), resin-bonded, fixed partial dentures (RBFPDs). A total of 40 Pd-Ag discs (diameter=5 mm) were prepared and divided into the following four groups (n=10): a) No sandblasting, used as a control; and b, 50 µm; c, 110 µm; and d, 250 µm aluminum oxide (Al 2 O 3 ) particles, respectively. Another 50 discs were pre-sandblasted and divided into five groups (n=10) subjected to different treatments: e) Sandblasting, used as a control; f) silane; g) alloy primer; h) silica coating + silane and i) silica coating + alloy primer. All 90 discs were bonded to enamel with Panavia F 2.0 and then subjected to shear bond strength (SBS) testing. The fracture surfaces were examined by scanning electron microscopy. Next, 40 missing maxillary second premolar models were restored with one of the four following RBFPD designs (n=10): I) A premolar occlusal bar combined with molar double rests (MDR); II) both occlusal bars with a wing (OBB); III) a premolar occlusal bar combined with a molar dental band (MDB); and IV) two single rests adjacent to the edentulous space with a wing (SRB) used as a control. All specimens were aged with thermal cycling and mechanical loading. Subsequently, they were loaded until broken. The data were analyzed by one-way analysis of variance. Al 2 O 3 (250 µm) abrasion provided the highest SBS (P<0.05). The alloy primer and silica + silane exhibited increased SBS. Furthermore, fracture analysis revealed that the failure mode varied among the different treatments. Whereas MDB exhibited the highest retention (P<0.05), that of OBB was greater than that of MDR (P<0.05), and the control exhibited the lowest retention. Abrasion with Al 2 O 3 (250 µm) effectively increased the adhesive property of Pd-Ag. Additionally, treatment with the alloy primer and silica coating + silane was able to

  18. Surface enhanced Raman scattering (SERS) study of L-arginine adsorbed on Ag nanoclusters on glass substrate by nanocluster deposition method

    Science.gov (United States)

    Botta, Raju; Bansal, C.

    2015-06-01

    Spheroidal shape Ag nanoclusters were prepared using inert gas phase condensation technique of cluster deposition system. Annealed the Ag nanocluster film at 300 °C to get proper size and also tune the surface plasmon resonance (SPR) with excitation wavelength. L- Arginine (L-Arg) amino acid was taken to study the quantitative nature of the Raman peaks with molar concentration. Wide range of aqueous solution of L-Arg amino acid was prepared by sequential dilution method (1 mM to 1 µM) and 40 µL of L-Arg was dropped on the Ag nanocluster film and allowed to dry in the ambient conditions. Further Raman measurements were carried out using 514 nm laser excitation sources. Guanidium fragment vibrational mode and COO- symmetric stretching mode peaks were taken for the quantitative measurement. All the SERS spectrums are in good agreement with earlier reports and are reproducible over the substrate. A good correlation between peak intensity and molar concentration was found. These results show promising applications in the protein analysis.

  19. Extrahepatic Manifestations of Hepatitis B Virus Infection: Addison’s Disease and Myelofibrosis in a Patient with Persistent Hepatitis B Surface Antigenemia

    Directory of Open Access Journals (Sweden)

    François Somlo

    1993-01-01

    Full Text Available A 60-year-old white male patient was admitted to the hospital with acute abdominal pain, seemingly a self-limited ileus. He was found to be hepatitis B surface antigen (HBsAg-positive. Previous dental treatment was suspected to be the initial source of the infection with hepatitis B virus. Five months later he was re-admitted with a diagnosis of adrenal insufficiency (Addison’s disease which responded well to steroids. Four years later he developed fever and leucocytosis. A bone marrow biopsy revealed myelofibrosis. He had several episodes of pyrexia during his lifetime. After a 12-year period the patient suffered a fatal myocardial infarction. At autopsy the adrenal glands were reduced to scarred remnants and HBsAg was found to be present in the residual adrenocortical cells by immunoflouresence methods. Bone marrow at autopsy revealed myelosclerosis as well HBsAg (via immunofluoresence. Hepatitis B virus was therefore closely correlated with the development of Addison’s disease and myelofibrosis in this case.

  20. Classical theory for the in-plane scattering of atoms from corrugated surfaces: application to the Ar-Ag(111) system.

    Science.gov (United States)

    Pollak, Eli; Miret-Artés, Salvador

    2009-05-21

    A classical Wigner in-plane atom surface scattering perturbation theory within the generalized Langevin equation formalism is proposed and discussed with applications to the Ar-Ag(111) system. The theory generalizes the well-known formula of Brako as well as the "washboard model." Explicit expressions are derived for the joint angular and final momentum distributions, joint final energy, and angular distributions as well as average energy losses to the surface. The theory provides insight into the intertwining between the energy loss and angular dependence of the scattering. At low energies the energy loss in the horizontal direction is expected to be large, leading to a shift of the maximum of the angular distribution to subspecular angles, while at high energies the energy loss in the vertical direction dominates, leading to a superspecular maximum in the angular distribution. The same effect underlies the negative slope of the average final (relative) energy versus scattering angle at low energies which becomes positive at high energies. The theory also predicts that the full width at half maximum of the angular distribution varies as the square root of the temperature. We show how the theory provides insight into the experimental results for scattering of Ar from the Ag(111) surface.

  1. Comparative Analysis of Cobalt Oxide Nanoisland Stability and Edge Structures on Three Related Noble Metal Surfaces: Au (111), Pt (111) and Ag (111)

    DEFF Research Database (Denmark)

    Fester, Jakob; Bajdich, Michal; Walton, Alexander

    2017-01-01

    Metal oxide nanostructures and thin films grown on metallic substrates have attracted strong attention as model catalysts and as interesting inverse catalyst systems in their own right. In this study, we investigate the role of metal support in the growth and stabilization of cobalt oxide...... nanostructures on the three related (111) surfaces of Au, Pt and Ag, as investigated by means of high-resolution scanning tunneling microscopy and DFT calculations. All three substrates promote the growth of crystalline CoOx (x = 1−2) islands under oxidative conditions, but we find several noteworthy differences...

  2. Hepatitis B surface antigen incorporated in dissolvable microneedle array patch is antigenic and thermostable.

    Science.gov (United States)

    Poirier, Danielle; Renaud, Frédéric; Dewar, Vincent; Strodiot, Laurent; Wauters, Florence; Janimak, Jim; Shimada, Toshio; Nomura, Tatsuya; Kabata, Koki; Kuruma, Koji; Kusano, Takayuki; Sakai, Masaki; Nagasaki, Hideo; Oyamada, Takayoshi

    2017-11-01

    Alternatives to syringe-based administration are considered for vaccines. Intradermal vaccination with dissolvable microneedle arrays (MNA) appears promising in this respect, as an easy-to-use and painless method. In this work, we have developed an MNA patch (MNAP) made of hydroxyethyl starch (HES) and chondroitin sulphate (CS). In swines, hepatitis B surface antigen (HBsAg) formulated with the saponin QS-21 as adjuvant, both incorporated in HES-based MNAP, demonstrated the same level of immunogenicity as a commercially available aluminum-adjuvanted HBsAg vaccine, after two immunizations 28 days apart. MNAP application was associated with transient skin reactions (erythema, lump, scab), particularly evident when the antigen was delivered with the adjuvant. The thermostability of the adjuvanted antigen when incorporated in the HES-based matrix was also assessed by storing MNAP at 37, 45 or 50 °C for up to 6 months. We could demonstrate that antigenicity was retained at 37 and 45 °C and only a 10% loss was observed after 6 months at 50 °C. Our results are supportive of MNAP as an attractive alternative to classical syringe-based vaccination. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. Enhanced photocatalytic activity of Ag-TiO2/Ag heterogeneous films

    Science.gov (United States)

    Liang, Ying; Wang, ShaoHua; Guo, PengFeng

    2015-11-01

    Ag-deposited TiO2 and Ag (Ag-TiO2/Ag) films coated on glass substrates were prepared using a simple sol-gel and dip-coating method. The Ag chemical state was investigated through X-ray diffractometry and X-ray photoelectron spectroscopy. Results showed that the Ag mainly exists in metallic state in the Ag-TiO2 film. Ag-TiO2/Ag exhibits higher photocatalytic activity than individual Ag-TiO2 and TiO2/Ag films. This enhanced photocatalytic activity was attributed to high surface plasmon resonance effects and separation rates of photoinduced electron-hole pairs of Ag nanoparticles. Results were verified by photoluminescence and UV-Vis spectroscopy.

  4. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/Cd(x)Zn(1 - x)S/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen.

    Science.gov (United States)

    Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

    2011-09-16

    Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/Cd(x)Zn(1 - x)S/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml( - 1).

  5. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/CdxZn1 - xS/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen

    Science.gov (United States)

    Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

    2011-09-01

    Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/CdxZn1 - xS/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml - 1.

  6. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/Cd{sub x}Zn{sub 1-x}S/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen

    Energy Technology Data Exchange (ETDEWEB)

    Shen Huaibin; Niu Jin Zhong; Xu Shasha; Zhou Changhua; Li Linsong [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Yuan Hang; Ma Lan, E-mail: malan@sz.tsinghua.edu.cn, E-mail: lsli@henu.edu.cn [Life Science Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

    2011-09-16

    Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/Cd{sub x}Zn{sub 1-x}S/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml{sup -1}.

  7. Transparent, flexible surface enhanced Raman scattering substrates based on Ag-coated structured PET (polyethylene terephthalate) for in-situ detection

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Zewen, E-mail: zuozewen@mail.ahnu.edu.cn; Zhu, Kai; Gu, Chuan; Wen, Yibing; Cui, Guanglei; Qu, Jun

    2016-08-30

    Highlights: • Transparent, flexible SERS substrates were prepared using techniques compatible with well-established silicon device technologies. • The SERS substrates exhibit high sensitivity and good reproducibility. • The high performance is related with the quasi-three-dimensional structure of the PET. • In-situ detection of analyte on irregular objects was achieved by this SERS substrate. - Abstract: Transparent, flexible surface-enhanced Raman scattering (SERS) substrates were fabricated by metalization of structured polyethylene terephthalate (PET) sheets. The resultant Ag-coated structured PET SERS substrates were revealed to be highly sensitive with good reproducibility and stability, an enhancement factor of 3 × 10{sup 6} was acquired, which can be attributed mainly to the presence of plentiful multiple-type hot spots within the quasi-three-dimensional surface of the structured PET obtained by oxygen plasma etching. In addition, detections of model molecules on fruit skin were also carried out, demonstrating the great potential of the Ag-coated structured PET in in-situ detection of analyte on irregular objects. Importantly, the technique used for the preparation of such substrate is completely compatible with well-established silicon device technologies, and large-area fabrication with low cost can be readily realized.

  8. Two-dimensional Ag/SiO2 and Cu/SiO2 nanocomposite surface-relief grating couplers and their vertical input coupling properties

    Science.gov (United States)

    Wang, Jun; Mu, Xiaoyu; Wang, Gang; Liu, Changlong

    2017-11-01

    By etching two SiO2 optical waveguide slabs separately implanted with 90 keV Ag ions and 60 keV Cu ions at the same dose of 6 × 1016 cm-2, two-dimensional Ag/SiO2 and Cu/SiO2 nanocomposite surface-relief grating couplers with 600-nm periodicity and 100-nm thickness were fabricated, and their structural and vertical input coupling properties were investigated. Experimental results revealed that the two couplers could convert light beams at wavelengths of 620-880 nm into guided waves with different efficiencies, highlighting the special importance of metal nanoparticles (NPs). Further discussions also revealed that owing to the introduction of periodically distributed metal NPs, the periodical phase modification of the transmitted beam was enhanced drastically, and the nanocomposite veins could behave as efficient light scatterers. As a result, the two couplers were much larger in coupling efficiency than the NP-free one with identical morphological parameters. The above findings may be useful to construct thin and short but efficient surface-relief grating couplers on glass optical waveguides.

  9. Quantum mechanics capacitance molecular mechanics modeling of core-electron binding energies of methanol and methyl nitrite on Ag(111) surface.

    Science.gov (United States)

    Löytynoja, T; Li, X; Jänkälä, K; Rinkevicius, Z; Ågren, H

    2016-07-14

    We study a newly devised quantum mechanics capacitance molecular mechanics (QMCMM) method for the calculation of core-electron binding energies in the case of molecules adsorbed on metal surfaces. This yet untested methodology is applied to systems with monolayer of methanol/methyl nitrite on an Ag(111) surface at 100 K temperature. It was found out that the studied C, N, and O 1s core-hole energies converge very slowly as a function of the radius of the metallic cluster, which was ascribed to build up of positive charge on the edge of the Ag slab. Further analysis revealed that an extrapolation process can be used to obtain binding energies that deviated less than 0.5 eV against experiments, except in the case of methanol O 1s where the difference was as large as 1.8 eV. Additional QM-cluster calculations suggest that the latter error can be connected to the lack of charge transfer over the QM-CMM boundary. Thus, the results indicate that the QMCMM and QM-cluster methods can complement each other in a holistic picture of molecule-adsorbate core-ionization studies, where all types of intermolecular interactions are considered.

  10. Microstructure, surface characterization and long-term stability of new quaternary Ti-Zr-Ta-Ag alloy for implant use.

    Science.gov (United States)

    Vasilescu, C; Osiceanu, P; Moreno, J M Calderon; Drob, S I; Preda, S; Popa, M; Dan, I; Marcu, M; Prodana, M; Popovici, I A; Ionita, D; Vasilescu, E

    2017-02-01

    The novel Ti-20Zr-5Ta-2Ag alloy was characterised concerning its microstructure, morphology, mechanical properties, its passive film composition and thickness, its long-term electrochemical stability, corrosion resistance, ion release rate in Ringer solution of acid, neutral and alkaline pH values and antibacterial activity. The new alloy has a crystalline α microstructure (by XRD). Long-term XPS and SEM analyses show the thickening of the passive film and the deposition of hydroxyapatite in neutral and alkaline Ringer solution. The values of the electrochemical parameters confirm the over time stability of the new alloy passive film. All corrosion parameters have very favourable values in time which attest a high resistance to corrosion. Impedance spectra evinced a bi-layered passive film formed by the barrier, insulating layer and the porous layer. The monitoring of the open circuit potentials indicated the stability of the protective layers and their thickening in time. The new alloy releases (by ICP-MS measurements) very low quantities of Ti, Zr, Ag ions and no Ta ions. The new alloy exhibits a low antibacterial activity. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Ag-protein plasmonic architectures for surface plasmon-coupled emission enhancements and Fabry-Perot mode-coupled directional fluorescence emission

    Science.gov (United States)

    Badiya, Pradeep Kumar; Patnaik, Sai Gourang; Srinivasan, Venkatesh; Reddy, Narendra; Manohar, Chelli Sai; Vedarajan, Raman; Mastumi, Noriyoshi; Belliraj, Siva Kumar; Ramamurthy, Sai Sathish

    2017-10-01

    We report the use of silver decorated plant proteins as spacer material for augmented surface plasmon-coupled emission (120-fold enhancement) and plasmon-enhanced Raman scattering. We extracted several proteins from different plant sources [Triticum aestivum (TA), Aegle marmelos (AM), Ricinus communis (RC), Jatropha curcas (JC) and Simarouba glauca (SG)] followed by evaluation of their optical properties and simulations to rationalize observed surface plasmon resonance. Since the properties exhibited by protein thin films is currently gaining research interest, we have also carried out simulation studies with Ag-protein biocomposites as spacer materials in metal-dielectric-metal planar microcavity architecture for guided emission of Fabry-Perot mode-coupled fluorescence.

  12. Relationships between the distribution of O atoms on partially oxidized metal (Al, Ag, Cu, Ti, Zr, Hf) surfaces and the adsorption energy: A density-functional theory study

    Science.gov (United States)

    Houska, J.; Kozak, T.

    2017-06-01

    We investigate the oxidation of selected metal (Al, Ag, Cu, Ti, Zr, and Hf) surfaces by the density functional theory. We go through a wide range of (233 per metal) distributions of O atoms on a partially oxidized metal surface. First, we focus on the qualitative information whether the preferred distribution of O atoms is heterogeneous (stoichiometric oxide + metal) or homogeneous (substoichiometric oxide). We find that the former is energetically preferred, e.g., for Al, while the latter is energetically preferred, e.g., for Ti, Zr, and Hf. Second, we provide the quantitative values of adsorption energies corresponding to the energetically preferred O atom distributions for various partial coverages of various metals by O. Third, we discuss and show an example of implications of the aforementioned findings for the understanding and simulations of sputtering.

  13. Surface Morphology Study of Nanostructured Lead-Free Solder Alloy Sn-Ag-Cu Developed by Electrodeposition: Effect of Current Density Investigation

    Directory of Open Access Journals (Sweden)

    Sakinah Mohd Yusof

    2013-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Nanostructured lead-free solder Sn-Ag-Cu (SAC was developed by electrodeposition method at room temperature. Electrolite bath which comprised of the predetermined quantity of tin methane sulfonate, copper sulfate and silver sulfate were added sequentially to MSA solution. The methane sulphonic acid (MSA based ternary Sn-Ag-Cu bath was developed by using tin methane sulfonate as a source of Sn ions while the Cu+ and Ag+ ions were obtained from their respective sulfate salts. The rate of the electrodeposition was controlled by variation of current density. The addition of the buffer, comprising of sodium and ammonium acetate helped in raising the pH solution. During the experimental procedure, the pH of solution, composition of the electrolite bath, and the electrodeposition time were kept constant. The electrodeposited rate, deposit composition and microstructure were investigated as the effect of current density. The electrodeposited solder alloy was characterized for their morphology using Field Emission Scanning Electron Microscope (FESEM. In conclusion, vary of current density will play significant role in the surface morphology of nanostructured lead-free solder SAC developed. Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New

  14. Dependence of surface-enhanced infrared absorption (SEIRA) enhancement and spectral quality on the choice of underlying substrate: a closer look at silver (Ag) films prepared by physical vapor deposition (PVD).

    Science.gov (United States)

    Killian, Michelle M; Villa-Aleman, Eliel; Sun, Zhelin; Crittenden, Scott; Leverette, Chad L

    2011-03-01

    Silver (Ag) films of varying thickness were simultaneously deposited using physical vapor deposition (PVD) onto six infrared (IR) substrates (BaF(2), CaF(2), Ge, AMTIR, KRS-5, and ZnSe) in order to correlate the morphology of the deposited film with optimal SEIRA response and spectral band symmetry and quality. Significant differences were observed in the surface morphology of the deposited silver films, the degree of enhancement provided, and the spectral appearance of para-nitrobenzoic acid (PNBA) cast films for each silver-coated substrate. These differences were attributed to each substrate's chemical properties, which dictate the morphology of the Ag film and ultimately determine the spectral appearance of the adsorbed analyte and the magnitude of SEIRA enhancement. Routine SEIRA enhancement factors (EFs) for all substrates were between 5 and 150. For single-step Ag depositions, the following ranking identifies the greatest SEIRA enhancement factor and the maximum absorption of the 1345 cm(-1) spectral marker of PNBA at the optimal silver thickness for each substrate: BaF(2) (EF = 85 ± 19, 0.059 A, 10 nm Ag) > CaF(2) (EF = 75 ± 30, 0.052 A, 10 nm Ag) > Ge (EF = 45 ± 8, 0.019 A, 5 nm Ag) > AMTIR (EF = 38 ± 8, 0.024 A, 15 nm Ag) > KRS-5 (EF = 24 ± 1, 0.015 A, 12 nm Ag) > ZnSe (EF = 9 ± 5, 0.008 A, 8 nm Ag). A two-step deposition provides 59% larger EFs than single-step depositions of Ag on CaF(2). A maximum EF of 147 was calculated for a cast film of PNBA (surface coverage = 341 ng/cm(2)) on a 10 nm two-step Ag film on CaF(2) (0.102 A, 1345 cm(-1) symmetric NO(2) stretching band). The morphology of the two-step Ag film has smaller particles and greater particle density than the single-step Ag film.

  15. Naturally occurring mutations in large surface genes related to occult infection of hepatitis B virus genotype C.

    Directory of Open Access Journals (Sweden)

    Hong Kim

    Full Text Available Molecular mechanisms related to occult hepatitis B virus (HBV infection, particularly those based on genotype C infection, have rarely been determined thus far in the ongoing efforts to determine infection mechanisms. Therefore, we aim to elucidate the mutation patterns in the surface open reading frame (S ORF underlying occult infections of HBV genotype C in the present study. Nested PCRs were applied to 624 HBV surface antigen (HBsAg negative Korean subjects. Cloning and sequencing of the S ORF gene was applied to 41 occult cases and 40 control chronic carriers. Forty-one (6.6% of the 624 Korean adults with HBsAg-negative serostatus were found to be positive for DNA according to nested PCR tests. Mutation frequencies in the three regions labeled here as preS1, preS2, and S were significantly higher in the occult subjects compared to the carriers in all cases. A total of two types of deletions, preS1 deletions in the start codon and preS2 deletions as well as nine types of point mutations were significantly implicated in the occult infection cases. Mutations within the "a" determinant region in HBsAg were found more frequently in the occult subjects than in the carriers. Mutations leading to premature termination of S ORF were found in 16 occult subjects (39.0% but only in one subject from among the carriers (2.5%. In conclusion, our data suggest that preS deletions, the premature termination of S ORF, and "a" determinant mutations are associated with occult infections of HBV genotype C among a HBsAg-negative population. The novel mutation patterns related to occult infection introduced in the present study can help to broaden our understanding of HBV occult infections.

  16. Correlation between the size and the magnetic properties of Ag2+ clusters loaded on ceria surface and their catalytic performance in the total oxidation of propylene. EPR study

    Science.gov (United States)

    Hany, Sara; Skaf, Mira; Aouad, Samer; Gennequin, Cédric; Labaki, Madona; Abi-Aad, Edmond; Aboukaïs, Antoine

    2018-03-01

    Three different types of Ag2+ ions ("a", "b", and "c") have been identified and examined by electron paramagnetic resonance (EPR) on 10% wt Ag/CeO2 prepared by impregnation method. One of them, Ag2+(b), behaves differently than the two others, Ag2+(a) and Ag2+(c), under redox atmospheres. The fact that, in reducing conditions (vacuum, propylene, hydrogen, and carbon black), Ag2+(a) and Ag2+(c) species were more easily reduced than Ag2+(b) ones, could not explain the catalytic performance and stability of this latter species compared to the first ones in the reaction of total oxidation of propylene. The EPR technique evidenced that Ag2+(b) species form, upon propene oxidation, a cluster. This cluster is composed of two parallel electron spins (dimer) and three nuclear spins (trimer). It seems that before propylene oxidation, Ag2+(b) clusters were ferromagnetic. This ferromagnetic character of Ag2+(b) species may explain their better catalytic performance, in propylene oxidation, than those of Ag2+(a) and Ag2+(c) ones.

  17. Observation of Dirac-like energy band and ring-torus Fermi surface associated with the nodal line in topological insulator CaAgAs

    Science.gov (United States)

    Takane, Daichi; Nakayama, Kosuke; Souma, Seigo; Wada, Taichi; Okamoto, Yoshihiko; Takenaka, Koshi; Yamakawa, Youichi; Yamakage, Ai; Mitsuhashi, Taichi; Horiba, Koji; Kumigashira, Hiroshi; Takahashi, Takashi; Sato, Takafumi

    2018-01-01

    One of key challenges in current material research is to search for new topological materials with inverted bulk-band structure. In topological insulators, the band inversion caused by strong spin-orbit coupling leads to opening of a band gap in the entire Brillouin zone, whereas an additional crystal symmetry such as point-group and nonsymmorphic symmetries sometimes prohibits the gap opening at/on specific points or line in momentum space, giving rise to topological semimetals. Despite many theoretical predictions of topological insulators/semimetals associated with such crystal symmetries, the experimental realization is still relatively scarce. Here, using angle-resolved photoemission spectroscopy with bulk-sensitive soft-x-ray photons, we experimentally demonstrate that hexagonal pnictide CaAgAs belongs to a new family of topological insulators characterized by the inverted band structure and the mirror reflection symmetry of crystal. We have established the bulk valence-band structure in three-dimensional Brillouin zone, and observed the Dirac-like energy band and ring-torus Fermi surface associated with the line node, where bulk valence and conducting bands cross on a line in the momentum space under negligible spin-orbit coupling. Intriguingly, we found that no other bands cross the Fermi level and therefore the low-energy excitations are solely characterized by the Dirac-like band. CaAgAs provides an excellent platform to study the interplay among low-energy electron dynamics, crystal symmetry, and exotic topological properties.

  18. Cesarean section reduces perinatal transmission of hepatitis B virus infection from hepatitis B surface antigen-positive women to their infants.

    Science.gov (United States)

    Pan, Calvin Q; Zou, Huai-Bin; Chen, Yu; Zhang, Xiaohui; Zhang, Hua; Li, Jie; Duan, Zhongping

    2013-10-01

    Despite appropriate passive and active immunization, perinatal transmission of hepatitis B virus (HBV) still occurs in 5%-10% of infants born to women with high levels of viremia who test positive for the hepatitis B e antigen (HBeAg). We evaluated the effects of cesarean section delivery on perinatal transmission of HBV from women who tested positive for the hepatitis B surface antigen (HBsAg). We analyzed data from 1409 infants born to HBsAg-positive mothers through vaginal delivery (VD) (n = 673), elective caesarean section (ECS) (n = 496), or urgent cesarean section (UCS) (n = 240) who completed appropriate immunization against HBV. The prevention was assumed to have failed for infants who were HBsAg positive when they were 7-12 months old; this information was used to assess transmission rates. HBV infection was transmitted to a smaller percentage of infants born by ECS (1.4%) than by VD (3.4%, P infection to their infants, regardless of method of delivery. There were no differences in maternal or infant morbidity and mortality among the groups. There is a significantly lower rate of vertical transmission of HBV infection to infants delivered by ECS, compared with those delivered vaginally or by UCS. Elective cesarean sections for HBeAg-positive mothers with pre-delivery levels of HBV DNA ≥1,000,000 copies/mL could reduce vertical transmission. Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.

  19. [Quantitative surface analysis of Pt-Co, Cu-Au and Cu-Ag alloy films by XPS and AES].

    Science.gov (United States)

    Li, Lian-Zhong; Zhuo, Shang-Jun; Shen, Ru-Xiang; Qian, Rong; Gao, Jie

    2013-11-01

    In order to improve the quantitative analysis accuracy of AES, We associated XPS with AES and studied the method to reduce the error of AES quantitative analysis, selected Pt-Co, Cu-Au and Cu-Ag binary alloy thin-films as the samples, used XPS to correct AES quantitative analysis results by changing the auger sensitivity factors to make their quantitative analysis results more similar. Then we verified the accuracy of the quantitative analysis of AES when using the revised sensitivity factors by other samples with different composition ratio, and the results showed that the corrected relative sensitivity factors can reduce the error in quantitative analysis of AES to less than 10%. Peak defining is difficult in the form of the integral spectrum of AES analysis since choosing the starting point and ending point when determining the characteristic auger peak intensity area with great uncertainty, and to make analysis easier, we also processed data in the form of the differential spectrum, made quantitative analysis on the basis of peak to peak height instead of peak area, corrected the relative sensitivity factors, and verified the accuracy of quantitative analysis by the other samples with different composition ratio. The result showed that the analytical error in quantitative analysis of AES reduced to less than 9%. It showed that the accuracy of AES quantitative analysis can be highly improved by the way of associating XPS with AES to correct the auger sensitivity factors since the matrix effects are taken into account. Good consistency was presented, proving the feasibility of this method.

  20. Surface-Enhanced Raman Scattering Activity of Ag/graphene/polymer Nanocomposite Films Synthesized by Laser Ablation

    Czech Academy of Sciences Publication Activity Database

    Siljanovska Petreska, G.; Blazevska-Gilev, J.; Fajgar, Radek; Tomovska, R.

    2014-01-01

    Roč. 564, AUG 1 (2014), s. 115-120 ISSN 0040-6090 Grant - others:NATO SfP(US) 984399 Institutional support: RVO:67985858 Keywords : laser ablation * surface-enhanced raman scattering * nanocomposite s * graphene * rhodamine 6G Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.759, year: 2014

  1. Investigating the parameters affecting the adsorption of amino acids onto AgCl nanoparticles with different surface charges.

    Science.gov (United States)

    Absalan, Ghodratollah; Ghaemi, Maryam

    2012-11-01

    In this paper, adsorption behaviors of typical neutral (alanine), acidic (glutamic acid) and basic (lysine) amino acids onto the surfaces of neutral as well as positively and negatively charged silver chloride nanoparticles were examined. Silver chloride nanoparticles with different charges and different water content were synthesized by reverse micelle method. The adsorptions of the above mentioned amino acids onto the surfaces of differently charged silver chloride nanoparticles were found to depend strongly on various parameters including pH of the aqueous solution, type of amino acid, water to surfactant mole ratio, and type of charges on the surfaces of silver chloride nanoparticles. It was found that the interaction of -NH(3) (+) groups of the amino acids with silver ion could be a driving force for adsorption of amino acids. Alanine and Glutamic acid showed almost similar trend for being adsorbed on the surface of silver chloride nanoparticles. Electrostatic interaction, hydrophobicity of both nanoparticle and amino acid, complex formation between amine group and silver ion, interaction between protonated amine and silver ion as well as the number of nanoparticles per unit volume of solution were considered for interpreting the observed results.

  2. A study of the properties of core/shell/shell Ag/FeCo/Ag nanoparticles

    Science.gov (United States)

    Kamzin, A. S.; Takahashi, M.; Maenosono, S.; Valiullin, A. A.

    2017-10-01

    The properties of heterophase core/shell/shell Ag/FeCo/Ag nanoparticles synthesized via a plasma method that are promising for biological applications are studied. As is established, the core/shell/shell Ag/FeCo/Ag nanoparticles exhibit a superparamagnetic state at room temperature that allows one to manage the hyperthermia process. The magnetic characteristics of core/shell/shell Ag/FeCo/Ag nanoparticles are interpreted by assuming partial oxidation of the surface layer of a ferromagnetic FeCo shell and formation of the antiferromagnetic CoxFe1-xO layer on the FeCo surface. The interaction between the surface antiferromagnetic CoxFe1-xO layer and the ferromagnetic FeCo shell causes the emergence of the exchange bias in Ag/FeCo/Ag nanoparticles.

  3. Time-domain analysis of surface-plasmon-polariton propagation in Ag nano-films using a generalized polarization approach

    KAUST Repository

    Al-Jabr, Ahmad

    2010-01-01

    A time-domain analysis of the propagation properties of surface-plasmon-polaritons (SPP) in Silver nanostructures is presented. The analysis is based on a simulation algorithm that unifies the formulation of different dispersion models and multi-pole relations into one form. The main objective of this work is to perform a comparative analysis between different dispersion models used for Silver, including Debye, Drude and multi-pole Lorentz-Drude models. The quantities that are used in the comparison are the SPP propagation length and propagation speed. Experimental results reported in literature are used to support the conclusions.

  4. Hybrid nanostructured Ag/ZnO decorated powder cellulose fillers for medical plastics with enhanced surface antibacterial activity.

    Science.gov (United States)

    Bazant, Pavel; Kuritka, Ivo; Munster, Lukas; Machovsky, Michal; Kozakova, Zuzana; Saha, Petr

    2014-11-01

    Hybrid inorganic-organic fillers based on nanostructured silver/zinc oxide decorations on micro-cellulose carrier particles were prepared by stepwise microwave assisted hydrothermal synthesis using soluble salts as precursors of silver and zinc oxide. Hexamethylenetetramine was used as precipitating agent for zinc oxide and reducing agent for silver. The inorganics covered all available surfaces of the cellulose particles with a morphology resembling a coral reef. Prepared particulate fillers were compounded to medical grade poly(vinyl chloride) matrix. Scanning electron microscopy and powder X-ray diffractometry were used to investigate the morphology and crystalline phase structure of fillers. The scanning electron microscopy was used for morphological study of composites. With respect to prospective application, the composites were tested on electrical and antibacterial properties. A small effect of water absorption in polymer composites on their dielectric properties was observed but no adverse effect of water exposure on prepared materials was manifested. Electrical conductivity of fillers and composites was measured and no influence of water soaking of composites was found at all. The surface antibacterial activity of prepared composites was evaluated according to the standard ISO 22196. Excellent performance against Escherichia coli and very high against Staphylococcus aureus was achieved.

  5. High Performance of PEDOT:PSS/n-Si Solar Cells Based on Textured Surface with AgNWs Electrodes

    Science.gov (United States)

    Jiang, Xiangyu; Zhang, Pengbo; Zhang, Juan; Wang, Jilei; Li, Gaofei; Fang, Xiaohong; Yang, Liyou; Chen, Xiaoyuan

    2018-02-01

    Hybrid heterojunction solar cells (HHSCs) have gained extensive research and attention due to simple device structure and low-cost technological processes. Here, HHSCs are presented based on a highly transparent conductive polymer poly(3,4ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) directly spin-coated on an n-type crystalline silicon with microscale surface textures, which are prepared by traditional chemical etching. We have studied interface properties between PEDOT:PSS and textured n-Si by varying coating conditions. Final power conversion efficiency (PCE) could arrive at 8.54% by these simple solution-based fabrication processes. The high conversion efficiency is attributed to the fully conformal contact between PEDOT:PSS film and textured silicon. Furthermore, the reflectance of the PEDOT:PSS layer on textured surface is analyzed by changing film thickness. In order to improve the performance of the device, silver nanowires were employed as electrodes because of its better optical transmittance and electrical conductivity. The highest PCE of 11.07% was achieved which displayed a 29.6% enhancement compared with traditional silver electrodes. These findings imply that the combination of PEDOT:PSS film and silver nanowire transparent electrodes pave a promising way for realizing high-efficiency and low-cost solar cells.

  6. Hepatitis B Viral Markers in Surface Antigen Negative Blood Donors ...

    African Journals Online (AJOL)

    Of the 20 who were anti-HBc positive, seven had tattoo/traditional marks on their body and one had previous history of blood transfusion. Conclusion: This study has shown that some potential blood units containing HBV are being transfused to patients unknowingly by screening for HBsAg only. Screening for other markers ...

  7. Sulfurization Study on the Ag and Ag-Pd Reflectors for GaN-Based LEDs

    Science.gov (United States)

    Chen, Y. H.; Liu, W. C.; Lin, Y. C.; Chung, C. C.; Zeng, W. J.; Chu, W. J.; Chung, T. Y.; Liu, C. Y.

    2016-01-01

    In this study, we have established a sulfurization resistance test, which is an immersion process in 0.01 M Na2S solution for 10 min. By using this process, we found that the sulfurized Ag reflector drops significantly over 52%. However, the Ag-Pd alloy reflector does not drop as much as the Ag reflector. The minimum reduction rate (around 20%) occurs at the Ag-Pd reflector with a Pd content of 3.72 at.%. It means that there is an optimal surface Pd content (around 3.72 at.%) for the reduction in reflectivity. Above, two effects of Pd alloying atoms on the sulfurization of the surface Ag atoms have been drawn, which are (1) chemical-state change effect and (2) surface microstructure effect. We found that the chemical-state change effect retards the sulfurization of the surface Ag atoms, but the surface microstructure effect (increase in Ag (111) plane) promotes the sulfurization of the surface Ag atoms. Here, we believe that these two opposite effects explain that there is an optimal Pd content on the Ag-Pd surface for the resistance of the sulfurization on the Ag surface.

  8. A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen

    Science.gov (United States)

    Lee, I.-K.; Jeun, M.; Jang, H.-J.; Cho, W.-J.; Lee, K. H.

    2015-10-01

    Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL-1) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor

  9. Experimental and theoretical investigation on photocatalytic activities of 1D Ag/Ag2WO4 nanostructures

    Science.gov (United States)

    Liu, Danqing; Huang, Weicheng; Li, Long; Liu, Lu; Sun, Xiaojun; Liu, Bo; Yang, Bin; Guo, Chongshen

    2017-09-01

    Ag2WO4 is a significant photocatalyst that responds to UV light irradiation only, which greatly hinders it for further practical application for solar light. To address this problem, herein, 1D plasmonic Ag/Ag2WO4 photocatalysts have been fabricated by a successive process including hydrothermal synthesis to obtain Ag2WO4 followed by an additional in situ chemical-reduction process for Ag decoration. Then, the structural features, optical properties, and electronic structures of Ag2WO4 and Ag/Ag2WO4 nanowires were systematically investigated via a combination of theoretical calculations and experimental evidence. The plasmon-enhanced Ag/Ag2WO4 nanowires exhibited higher visible-light-driven photocatalytic activity, which performed a desired photodestruction ratio of 91.2% on methylene blue within 60 min and good stability in five cycles. The Ag decoration greatly facilitates visible-light harvesting and thus promotes photogenerated radical oxidation to dye, which is evidenced by the higher hydroxyl radical level of Ag/Ag2WO4 detected in the ESR test during the photocatalytic process. The theoretical calculation based on density functional theory indicates that Ag nanoparticles formed on the surface of Ag2WO4 could narrow the band gap of Ag2WO4. In addition, the surface plasmon resonance absorption effect and fast charge transfer effect in the metal-semiconductor system contribute to the photocatalytic performance of Ag/Ag2WO4.

  10. Resolution of HBV infection occurs sooner than recovery of renal disease in adult serum HBsAg-negative HBV-associated glomerulonephritis.

    Science.gov (United States)

    Xu, Fang; Wang, Chong; Shi, Xiaoju; Hou, Jie; Guo, Xiaolin; Gao, Pujun

    2018-05-02

    Most cases of hepatitis B virus-associated glomerulonephritis (HBV-GN) occur in children and present with serum HBsAg positivity. Few studies have investigated adult HBV-GN patients who are serum HBsAg-negative. This study aimed to determine the clinical and pathological features of serum HBsAg-negative adult HBV-GN patients. Clinical, pathologic and laboratory findings were collected and analyzed in a cohort of 27 adult HBV-GN patients who were serum HBsAg negative upon diagnosis. The study population included mostly men of middle age (40-59 years). Clinically, patients presented with nephrotic syndrome. Serum IgG levels were low, while serum IgM, IgA, C3, and C4 levels as well as liver and renal function tests were normal in most or all patients. Among the 27 patients, 21 tested positively for HBV antibodies. MN was the dominant pathological form on kidney biopsy. In addition, only a few patients showed a "full house" staining pattern and renal immune deposit of C1q. Serum HBsAg negative HBV-GN may represent a late stage of HBV infection. We recommend routine testing for HBV markers on renal biopsy in regions where HBV is prevalent, even when tests for serum HBV markers are negative. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  11. Development of anti-hepatitis B surface (HBs) antibodies after HBs antigen loss in HIV-hepatitis B virus co-infected patients.

    Science.gov (United States)

    Boyd, Anders; Canini, Laetitia; Gozlan, Joël; Lascoux-Combe, Caroline; Miailhes, Patrick; Fonquernie, Laurent; Girard, Pierre-Marie; Lacombe, Karine

    2017-10-01

    Hepatitis B surface antigen (HBsAg)-seroconversion, or loss of HBsAg and acquisition of anti-hepatitis B surface (HBs) antibodies, defines functional cure of chronic hepatitis B virus (HBV) infection. After HBsAg-loss, little is known regarding the development of anti-HBs antibodies and even less so in individuals co-infected with HIV. To determine anti-HBs antibody kinetics after HBsAg-loss and explore determinants of HBsAg-seroconversion in HIV-HBV co-infected patients. Patients enrolled in the French HIV-HBV cohort were included if they had >1 study visit after HBsAg-loss. Individual patient kinetics of anti-HBs antibody levels were modeled over time using mixed-effect non-linear regression, whereby maximum specific growth rate and maximal level of antibody production were estimated from a Gompertz growth equation. Fourteen (4.6%) of 308 co-infected patients followed in the cohort exhibited HBsAg-loss, all of whom were undergoing antiretroviral therapy. Nine (64.3%) of these patients achieved HBsAg-seroconversion during a median 3.0 years (IQR=1.1-5.1) after HBsAg-loss. Across individuals with HBsAg-seroconversion, the fastest rates of antibody growth ranged between 0.57-1.93year -1 (population maximum growth rate=1.02) and antibody production plateaued between 2.09-3.66 log 10 mIU/mL at the end of follow-up (population maximal antibody levels=2.66). Patients with HBsAg-seroconversion had substantial decreases in HBV DNA viral loads (P=0.03) and proportion with elevated ALT levels (P=0.02) and HBeAg-positive serology (P=0.08). No such differences were observed in those without HBsAg-seroconversion. Most co-infected patients with HBsAg-seroconversion produced and maintained stable antibody levels, yet kinetics of anti-HBs production were much slower compared to those observed post-vaccination or after clearance of acute HBV-infection. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Influence of insolubility of silver on the Hirshfeld surface analyses and magnetic behavior of La0.5Ca0.1Ag0.4MnO3 compound

    Science.gov (United States)

    Felhi, H.; Smari, M.; Walha, I.; Dhahri, E.; Valente, M. A.; Bessais, L.

    2018-01-01

    In the present study, we report a detail investigation on the effect of insolubility of Ag 40% doping on the structural and magnetic properties of LCMO-Ag compound prepared by solid-state reaction. The analysis of X-ray diffraction for our samples using Rietveld refinement showed that they crystallize in the orthorhombic structure with Pnma space group. We have shown that this compound has a secondary phase (Ag metallic phase). The detailed analyses of Hirshfeld surface and fingerprint plots provide insight into the nature of intermolecular interactions in the title compound. Magnetization measurements versus temperature at different magnetic fields have shown the presence of two magnetic transitions. This result was confirmed previously in the crystallographic study. This phase exhibits magnetic properties, which has a Curie temperature (Tc) which is lower than the Curie temperature of the FM-PM transition. The critical properties of perovskite manganite LCMO-Ag around of transition with Tc = 230 K is investigated through various techniques such as modified Arrott plot, Kouvel-Fisher method, and critical isotherm analysis. Moreover, the critical exponents also obeyed the single scaling equation of M(H, ɛ)|ɛ|-β = f±(H|ɛ|-(β+γ)). We find that the critical exponent for LCMO-Ag is close to that theoretically predicted for mean field tricritical model.

  13. Single cell imprinting on the surface of Ag-ZnO bimetallic nanoparticle modified graphene oxide sheets for targeted detection, removal and photothermal killing of E. Coli.

    Science.gov (United States)

    Roy, Ekta; Patra, Santanu; Tiwari, Ashutosh; Madhuri, Rashmi; Sharma, Prashant K

    2017-03-15

    A very cost-effective, fast, sensitive and specific imprinted polymer modified electrochemical sensor for the targeted detection, removal and destruction of Escherichia coli bacteria was developed onto the surface of Ag-ZnO bimetallic nanoparticle and graphene oxide nanocomposite. The nanocomposite played a dual role in this work, as a platform for imprinting of bacteria as well as a participated in their laser-light induced photo killing. In terms of sensing, our proposed sensor can detect E. Coli as few as 10CFUmL -1 and capture 98% of bacterial cells from their very high concentrated solution (10 5 CFUmL -1 ). Similarly to the quantitative detection, we have also investigated the quantitative destruction of E. Coli and found that 16.0cm 2 area of polymer modified glass plate is sufficient enough to kill 10 5 CFUmL -1 in the small time span of 5 minutes. The obtained results suggest that our proposed sensor have potential to serve as a promising candidate for specific and quantitative detection, removal as well as the destruction of a variety of bacterial pathogens. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Green synthesis of graphene/Ag nanocomposites

    International Nuclear Information System (INIS)

    Yuan Wenhui; Gu Yejian; Li Li

    2012-01-01

    Graphical abstract: A facile and green approach to synthesis of GNS/AgNPs is reported by employing sodium citrate as reductant, and this study represents the use of biocompounds for nontoxic and scalable production of GNS/AgNPs under a suitable concentration of silver ions and the prepared GNS/AgNPs can be used in the field of disinfection. Highlights: ► Graphene/Ag nanocomposites were prepared by a green and facile strategy based on sodium citrate. ► The influence of AgNO 3 amount on particle size and size range of AgNPs was studied. ► The surface plasmon resonance properties of AgNPs on graphene was investigated. ► The antibacterial activity of silver nanoparticles was retained in the nanocomposites. - Abstract: Graphene/Ag nanocomposites (GNS/AgNPs) were fabricated via a green and facile method, employing graphite oxide (GO) as a precursor of graphene, AgNO 3 as a precursor of Ag nanoparticles, and sodium citrate as an environmentally friendly reducing and stabilizing agent. The synthesized GNS/AgNPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectra (RS), respectively. The results indicated that graphite oxide was completely reduced to graphene, and the silver ion was reduced by sodium citrate simultaneously. Under a suitable dosage of silver ions, well-dispersed AgNPs on the graphene sheets mostly centralized at 20–25 nm. The surface plasmon resonance property of AgNPs on graphene showed that there was a interaction between AgNPs and graphene supports. In addition, antibacterial activity of silver nanoparticles was retained in the nanocomposites, suggesting that they can be potentially used as a graphene-based biomaterial.

  15. A highly sensitive radioimmunoassay technique for subtyping the antibody to hepatitis B surface antigen

    International Nuclear Information System (INIS)

    Fang, C.T.; Nath, N.; Berberian, H.; Dodd, R.Y.

    1978-01-01

    A highly sensitive technique for determining the subtype specificity of antibody to hepatitis B surface antigen (anti-HBs) is described. Immunoadsorbent consisting of controlled pore glass coated with subtype specific HBsAg was used to remove homologous antibody from the test samples before testing them for residual antibody by a commercially available radioimmunoassay (RIA). A total of 73 anti-HBs-positive samples from asymptomatic blood donors were tested. In nearly 80% of these samples the subtype reactivity could be determined by this technique. Only 67% could be typed by conventional liquid phase absorption RIA and 22% by passive hemagglutination inhibition techniques. Among the samples with low anti-HBs titer, ad and ay subtypes were found with equal frequency; however, with the increase in anti-HBs titer, considerably higher proportion of ad specificity was detected. (Auth.)

  16. Green synthesis of Ag-Cr-AC nanocomposites by Azadirachta indica and its application for the simultaneous removal of binary mixture of dyes by ultrasonicated assisted adsorption process using Response Surface Methodology.

    Science.gov (United States)

    Saad, Muhammad; Tahir, Hajira; Ali, Duaa

    2017-09-01

    In the present studies the Ag-Cr-AC nanocomposites were synthesized by Azadirachta indica leaves extract. They were inoculated on the amorphous surface of activated carbon. The surface morphology and structural identification was determined by SEM, FTIR and XRD techniques. The simultaneous removal of binary dye system of Reactive Red and Crystal Violet were performed by ultrasonicated assisted adsorption process utilizing Ag-Cr-AC nanocomposites. Central Composite Design (CCD) having 5 factors of time, pH, amount of Ag-Cr-AC (adsorbent), concentrations of Reactive Red (RR) and Crystal Violet (CV) was employed. Response Surface Methodology was applied to study the Optimum Operating Parameters (OOP) for the adsorption process. The current studies showed that they can be efficiently employed to remove the coloured effluent from aqueous media as the simultaneous removal of dyes was observed to be 64.92% and 82.47% for RR and CV dyes respectively. Adsorption equilibrium was studied by Freundlich, Langmuir, Dubinin-Radushkevich, Temkin and Harkins-Jura Isotherm Models. The Langmuir isotherm was observed to be followed by the RR-Ag-Cr-AC system while CV-Ag-Cr-AC followed Harkins-Jura Isotherm model. For the binary system, the removal of CV and RR dyes by the nanocomposites obeyed Harkins-Jura model at temperature of 40°C. Thermodynamics studies affirmed the spontaneous nature of adsorption process. pH pzc was evaluated to be 6.29. The purification cost per cubic meter of the effluent was evaluated to be US$ 85.08. The proposed method might prove to be an efficient and cost effective way to eradicate color from the binary mixture of RR and CV dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Surface-enhanced Raman scattering (SERS) of riboflavin on nanostructured Ag surfaces: The role of excitation wavelength, plasmon resonance and molecular resonance

    Science.gov (United States)

    Šubr, Martin; Kuzminova, Anna; Kylián, Ondřej; Procházka, Marek

    2018-05-01

    Optimization of surface-enhanced Raman scattering (SERS)-based sensors for (bio)analytical applications has received much attention in recent years. For optimum sensitivity, both the nanostructure fabrication process and the choice of the excitation wavelength used with respect to the specific analyte studied are of crucial importance. In this contribution, detailed SERS intensity profiles were measured using gradient nanostructures with the localized surface-plasmon resonance (LSPR) condition varying across the sample length and using riboflavin as the model biomolecule. Three different excitation wavelengths (633 nm, 515 nm and 488 nm) corresponding to non-resonance, pre-resonance and resonance excitation with respect to the studied molecule, respectively, were tested. Results were interpreted in terms of a superposition of the enhancement provided by the electromagnetic mechanism and intrinsic properties of the SERS probe molecule. The first effect was dictated mainly by the degree of spectral overlap between the LSPR band, the excitation wavelength along with the scattering cross-section of the nanostructures, while the latter was influenced by the position of the molecular resonance with respect to the excitation wavelength. Our experimental findings contribute to a better understanding of the SERS enhancement mechanism.

  18. Raman Reporter-Coupled Ag(core)@Au(shell) Nanostars for in Vivo Improved Surface Enhanced Raman Scattering Imaging and Near-infrared-Triggered Photothermal Therapy in Breast Cancers.

    Science.gov (United States)

    Zeng, Leyong; Pan, Yuanwei; Wang, Shouju; Wang, Xin; Zhao, Xinmei; Ren, Wenzhi; Lu, Guangming; Wu, Aiguo

    2015-08-05

    Noble-metal nanomaterials were widely investigated as theranostic systems for surface enhanced Raman scattering (SERS) imaging, and also for photothermal therapy (PTT) of cancers. However, it was still a major challenge to explore multifunctional nanoprobes with high performance, high stability, and low toxicity. In this work, Raman reporter (DTTC)-coupled Agcore@Aushell nanostars (Ag@Au-DTTC) were synthesized and investigated for in vivo improved SERS imaging and near-infrared (NIR)-triggered PTT of breast cancers. By the two-step coupling of DTTC, the SERS signal was improved obviously, and the cytotoxicity of nanoparticles was also decreased by coating Au nanostars onto Ag nanoparticles. The as-prepared Ag@Au-DTTC nanostars showed high photostability and excellent photothermal performance, in which the photothermal conversion efficiency was up to 79.01% under the irradiation of an 808 nm laser. The in vitro and in vivo SERS measurements of Ag@Au-DTTC nanostars showed that the many sharp and narrow Raman peaks located at 508, 782, 844, 1135, 1242, 1331, 1464, 1510, and 1580 cm(-1) could be obviously observed in MCF-7 cells and in MCF-7 tumor-bearing nude mice, compared with that in pure DTTC. In 14-day treatments, the tumor volume of MCF-7 tumor-bearing nude mice injected with Ag@Au-DTTC nanostars and irradiated by an 808 nm laser almost disappeared. This study demonstrated that the as-prepared Ag@Au-DTTC nanostars could be excellent multifunctional agents for improved SERS imaging and NIR-triggered PTT of breast cancers with low risk.

  19. Electrochemical sensing and photocatalysis using Ag-TiO 2 ...

    Indian Academy of Sciences (India)

    The superior performance of the Ag-TiO2 composite microwires is attributed to improved surface reactivity, mass transport and catalytic property as a result of wiring the TiO2 surface with Ag nanoparticles. Compared to the TiO2 microwires, Ag-TiO2 microwires exhibited three times higher sensitivity in the detection of ...

  20. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anamika [Department of Life Sciences, University of Mumbai, Santacruz (E), Mumbai 400 098 (India); Dutta, Dimple P., E-mail: dimpled@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ballal, A. [Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Fulekar, M.H. [School of Environment and Sustainable Development, Central University of Gujarat, Gandhinagar 382 030, Gujarat (India)

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  1. Tuning the charge state of Ag and Au atoms and clusters deposited on oxide surfaces by doping: a DFT study of the adsorption properties of nitrogen- and niobium-doped TiO2 and ZrO2.

    Science.gov (United States)

    Schlexer, Philomena; Ruiz Puigdollers, Antonio; Pacchioni, Gianfranco

    2015-09-14

    The charge state of Ag and Au atoms and clusters (Ag4 and Au4, Ag5 and Au5) adsorbed on defective TiO2 anatase(101) and tetragonal ZrO2(101) has been systematically investigated as a function of oxide doping and defectivity using a DFT+U approach. As intrinsic defects, we have considered the presence of oxygen vacancies. As extrinsic defects, substitutional nitrogen- and niobium-doping have been investigated, respectively. Both surface and sub-surface defects and dopants have been considered. Whereas on surfaces with oxygen vacancies or Nb-doping, atoms and clusters may become negatively charged, N-doping always leads to the formation of positively charged adsorbates, independently of the supporting material (TiO2 or ZrO2). This suggests the possibility to tune the electronic properties of supported metal clusters by selective doping of the oxide support, an effect that may result in complete changes in chemical reactivity.

  2. Prevalence of Hepatitis B surface antigen in children with sickle cell anemia

    Directory of Open Access Journals (Sweden)

    Baba Jibrin

    2014-01-01

    Full Text Available Background: Hepatitis B virus is known to be endemic in Africa. The seroepidemiological studies of HBV have shown that infection commonly occurs in childhood in Africa resulting in an increased tendency to chronicity. This cross-sectional study was undertaken to determine the seroprevalence of hepatitis B surface antigen among pediatric patients with homozygous hemoglobin S. Materials and Methods: Three hundred sickle cell anemia children aged 6 months-15 years (both in steady state and in crises attending the SCA clinic and on admission in emergency pediatrics unit and pediatrics medical ward, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria, were screened for hepatitis B infection using HBsAg as marker of infection. The sensitive enzyme linked immunosorbent assay method was used for detection of the marker. Three hundred children with minor illness attending pediatrics outpatient department and on admission in EPU/PMW for various treatment in the same hospital served as gender- and age-marched controls cohorts. Results: The sero-prevalence of HBsAg seropositivity for hepatitis B virus infection among SCA children was 17.3% (52/300 compared to 10.7% (32/300 of the control (P = 0.0875. The peak prevalence age group for HBV infection among SCA children was in the age group 1.1-5.0 years (6% compared to 10.1-15.0 years (4.7% in the control. Risk factors for HBV infection such as blood transfusion, traditional scarification/circumcision/uvulectomy, and tattooing did not significantly affect the prevalence of HBV infection in both SCA children and controls. Conclusion: Hepatitis B infection is common in Sokoto. The need for strict adherence to HBV immunization and further community-based studies on the risk factors are recommended.

  3. Controllable Charge Transfer in Ag-TiO₂ Composite Structure for SERS Application.

    Science.gov (United States)

    Wang, Yaxin; Yan, Chao; Chen, Lei; Zhang, Yongjun; Yang, Jinghai

    2017-06-28

    The nanocaps array of TiO₂/Ag bilayer with different Ag thicknesses and co-sputtering TiO₂-Ag monolayer with different TiO₂ contents were fabricated on a two-dimensional colloidal array substrate for the investigation of Surface enhanced Raman scattering (SERS) properties. For the TiO₂/Ag bilayer, when the Ag thickness increased, SERS intensity decreased. Meanwhile, a significant enhancement was observed when the sublayer Ag was 10 nm compared to the pure Ag monolayer, which was ascribed to the metal-semiconductor synergistic effect that electromagnetic mechanism (EM) provided by roughness surface and charge-transfer (CT) enhancement mechanism from TiO₂-Ag composite components. In comparison to the TiO₂/Ag bilayer, the co-sputtered TiO₂-Ag monolayer decreased the aggregation of Ag particles and led to the formation of small Ag particles, which showed that TiO₂ could effectively inhibit the aggregation and growth of Ag nanoparticles.

  4. Surface reconstruction of titania with g-C3N4 and Ag for promoting efficient electrons migration and enhanced visible light photocatalysis

    International Nuclear Information System (INIS)

    Leong, Kah Hon; Liu, Sze Ling; Sim, Lan Ching; Saravanan, Pichiah; Jang, Min; Ibrahim, Shaliza

    2015-01-01

    Graphical abstract: - Highlights: • Visible light responsive TiO 2 was reconstructed with g-C 3 N 4 and Ag by simple route. • g-C 3 N 4 simultaneously promoted electrons migration and tuned energy gap of TiO 2 . • Ag facilitated electron junction and enhanced the visible light through SPR. • Reconstructed TiO 2 showed an excellent photocatalytic performance by removing AMX. - Abstract: The developments of heterogeneous photocatalysts are one among the competent reconstruction approach to enrich the visible light responsiveness of conventional TiO 2 . In the present work the TiO 2 was reconstructed with graphitic carbon nitride (g-C 3 N 4 ) and silver (Ag) to form a ternary (g-C 3 N 4 )–Ag/TiO 2 . The graphitic carbon nitride an intriguing material was prepared through a facile pyrolysis by using urea as a precursor. The silver (Ag) that plays a role as electron-conduction mobiliser in the ternary was synthesised through solar mediated photodeposition method. The synthesised ternary composite characteristics were thoroughly investigated through various physical and chemical analyses. The presence of g-C 3 N 4 in the ternary photocatalysts promoted the formation of interface between the Ag/TiO 2 and g-C 3 N 4 and stimulated the electron transfer between them. These electrons migration acknowledged by the synergic effect prolonged the lifetime of charge carriers. The g-C 3 N 4 also significantly tuned the energy band of conventional TiO 2 . The prepared ternary exhibited significantly high visible light photocatalytic performance by degrading Amoxicillin (AMX) a poor photosensitising pollutant at highest rate.

  5. Surface reconstruction of titania with g-C{sub 3}N{sub 4} and Ag for promoting efficient electrons migration and enhanced visible light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Leong, Kah Hon; Liu, Sze Ling [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Sim, Lan Ching [Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, 31900 Kampar, Perak (Malaysia); Saravanan, Pichiah, E-mail: saravananpichiah@um.edu.my [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nanotechnology & Catalysis Research Center (NANOCAT), University of Malaya, 50603 Kuala Lumpur (Malaysia); Jang, Min [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nanotechnology & Catalysis Research Center (NANOCAT), University of Malaya, 50603 Kuala Lumpur (Malaysia); Ibrahim, Shaliza [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-12-15

    Graphical abstract: - Highlights: • Visible light responsive TiO{sub 2} was reconstructed with g-C{sub 3}N{sub 4} and Ag by simple route. • g-C{sub 3}N{sub 4} simultaneously promoted electrons migration and tuned energy gap of TiO{sub 2}. • Ag facilitated electron junction and enhanced the visible light through SPR. • Reconstructed TiO{sub 2} showed an excellent photocatalytic performance by removing AMX. - Abstract: The developments of heterogeneous photocatalysts are one among the competent reconstruction approach to enrich the visible light responsiveness of conventional TiO{sub 2}. In the present work the TiO{sub 2} was reconstructed with graphitic carbon nitride (g-C{sub 3}N{sub 4}) and silver (Ag) to form a ternary (g-C{sub 3}N{sub 4})–Ag/TiO{sub 2}. The graphitic carbon nitride an intriguing material was prepared through a facile pyrolysis by using urea as a precursor. The silver (Ag) that plays a role as electron-conduction mobiliser in the ternary was synthesised through solar mediated photodeposition method. The synthesised ternary composite characteristics were thoroughly investigated through various physical and chemical analyses. The presence of g-C{sub 3}N{sub 4} in the ternary photocatalysts promoted the formation of interface between the Ag/TiO{sub 2} and g-C{sub 3}N{sub 4} and stimulated the electron transfer between them. These electrons migration acknowledged by the synergic effect prolonged the lifetime of charge carriers. The g-C{sub 3}N{sub 4} also significantly tuned the energy band of conventional TiO{sub 2}. The prepared ternary exhibited significantly high visible light photocatalytic performance by degrading Amoxicillin (AMX) a poor photosensitising pollutant at highest rate.

  6. Synthesis of Cu-Ag@Ag particles using hyperbranched polyester as template

    Science.gov (United States)

    Han, Wen-Song

    2015-07-01

    In this manuscript, the third-generation hyperbranched polyester was synthesized with 2, 2-dimethylol propionic acid as AB2 monomer and pentaerythrite as core molecule by using step by step polymerization process at first. Then, the Cu-Ag particles were prepared by co-reduction of silver nitrate and copper nitrate with ascorbic acid in the aqueous solution using hyperbranched polyester as template. Finally, the Cu-Ag@Ag particles were prepared by coating silver on the surface of Cu-Ag particles by reduction of silver nitrate. The synthesized hyperbranched polyester and Cu-Ag@Ag particles were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectra, x-ray diffraction, Laser light scattering, thermogravimetric analysis (TGA) and SEM. UV-vis spectra results showed that the Cu-Ag@Ag particles had a strong absorption band at around 420 nm. Laser light scattering and SEM studies confirmed that the most frequent particle sizes of Cu-Ag@Ag particles were 1.2 um. TGA results indicated that the Cu-Ag@Ag particles had good thermal stability. [Figure not available: see fulltext.

  7. Hepatitis B virus surface antigen and antibody markers in children at ...

    African Journals Online (AJOL)

    SUMMARY. Objectives: The knowledge about outcomes of infant vaccination against HBV infections using the DPT-HepB-Hib vaccine in Ghana is limited. This study therefore investigated the levels of immunity to HBV among children who received the DPT-HepB-Hib vaccine and HBsAg carriage in non-responders.

  8. Surface protein mutations in chronic hepatitis B patients who received hepatitis B vaccine therapy

    Directory of Open Access Journals (Sweden)

    Maryam Daram

    2014-09-01

    Conclusion: In chronic carriers who already had HBsAg variants selected by the host-immune response, any immune stimulation by the vaccine had no effect on the chronic state of these patients or selected any remarkable escape mutants. Newer strategies should be considered based on third generation or the use of DNA vaccines or new adjuvants.

  9. Risk Factors and Sero-Prevalence of Hepatitis B Surface Antigen ...

    African Journals Online (AJOL)

    Background: Availability of safe blood and blood products for transfusion is increasingly difficult globally, especially in developing countries because of high prevalence of Transfusion Transmissible Infections. Objectives: To determine the prevalence of HBsAg among blood donors and to evaluate the socio-economic, ...

  10. Survey of HBsAg-positive pregnant women and their infants regarding measures to prevent maternal-infantile transmission

    Directory of Open Access Journals (Sweden)

    Meina Hu

    2010-02-01

    Full Text Available Abstract Background Intrauterine infection is the main contributor to maternal-infantile transmission of HBV. This is a retrospective study of 158 HBsAg-positive pregnant women who delivered children from Jan 1st, 2004 to Dec.31th, 2006 in Wuhan City, China. We investigated the measures taken to prevent maternal-infantile transmission of hepatitis B virus and the infection status of children. Methods HBsAg-positive pregnant women were selected by a random sampling method when they accepted prenatal care in district-level Maternal and Child Health Hospitals. On a voluntary basis, these women completed questionnaires by face-to-face or phone interviews. The collected data were used to evaluate the immunization programs that pregnant women had received for preventing hepatitis B maternal-infantile transmission. Results Among the 158 women, 143(90.5% received Hepatitis B immune globulin during pregnancy, and 86.0% of their children were given Hepatitis B immune globulin and Hepatitis B vaccine. The rate of cesarean section was 82.3%, and 28.5% of these were aimed at preventing HBV infection. The rate of bottle feeding was 51.9%, and 89.0% of bottle feeding cases were for the purpose of preventing HBV infection. There were 71 cases of participants who were HBeAg-positive. Compared with the HBsAg+ HBeAg- group (only HBsAg-positive, the HBsAg + HBeAg+ group (HBsAg-positive and HBeAg-positive had significantly higher rates of the caesarean section and bottle feeding resulting from hepatitis B (P Conclusion Most HBsAg positive pregnant women have a growing awareness of maternal-infantile transmission of Hepatitis B virus and are receiving some form of preventative treatment, like combined immunization. Caesarean and bottle feeding are very common, often primarily to prevent transmission. Relatively few intrauterine infections were identified in this sample, but many infants did not appear to seroconvert after vaccination.

  11. Predictive Value of Hepatitis B Core-Related Antigen (HBcrAg) During the Natural History of Hepatitis B Virus Infection.

    Science.gov (United States)

    Gou, Yu; Zhao, Yanhua; Rao, Chenli; Feng, Shu; Wang, Tingting; Li, Dongdong; Tao, Chuanmin

    2017-07-01

    The natural history of HBV infection includes immune tolerance (IT), immune clearance (IC), HBeAg-negative inactive/quiescent carrier (ENQ), and HBeAg-negative hepatitis (ENH) phases. As the current biomarkers for discriminating the four phases still have some weaknesses, additional serological indicators are needed. Hepatitis B core-related antigen (HBcrAg) encoded with the precore/core gene contains denatured HBeAg, HBV core antigen (HBcAg), and a 22-KDa precore protein (p22cr) and has been demonstrated to have a close association with the natural history of hepatitis B infection. However, no specific cutoff values and diagnostic parameters have been identified to evaluate the diagnostic efficacy. This study aimed to clarify the distribution of HBcrAg levels and evaluate the diagnostic performance during the natural history of HBV infection in a Western Chinese population. In this study, 294 samples were collected from treatment-naive HBV infection patients in different phases (IT = 64; IC = 72; ENQ = 100, and ENH = 58). We detected the HBcrAg values and analyzed the relationship between HBcrAg and HBV DNA. HBsAg and other clinical parameters were quantitatively detected. The HBcrAg levels of IT, IC, ENQ, and ENH were 9.30 log U/mL, 8.80 log U/mL, 3.00 log U/mL, and 5.10 log U/mL, respectively (p < 0.0001). Receiver operating characteristic curve analysis demonstrated that the areas under the curves (AUCs) for HBcrAg and quantitative HBsAg at cutoff values of 9.25 log U/mL and 4.355 log IU/mL for distinguishing the IT phase from the IC phase were 0.704 and 0.694, with a sensitivity of 53.13% and 79.69% and specificity of 76.39% and 59.72%, respectively. AUCs of HBcrAg and quantitative HBsAg at cutoff values of 4.15 log U/mL and 2.395 log IU/mL for discriminating between the ENQ and ENH phases were 0.931 and 0.653, with a sensitivity of 87.93% and 91.38% and specificity of 84.00% and 39.00%, respectively. HBcrAg levels varied significantly among the four natural

  12. Synthesis and characterizations of AgSCN nanospheres using AgCl as the precursor

    International Nuclear Information System (INIS)

    Yang Ming; Ma Jing

    2009-01-01

    Nanospheres of AgSCN with an average radius of 30-80 nm have been prepared by a simple reaction between AgCl suspension and KSCN in the presence of gelatin. Gelatin played a decisive role as an inhibitor of the direct attack of SCN - ions to AgCl surfaces and coagulation of the growing AgSCN in producing the spherical AgSCN nanoparticles. The products were characterized by X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectra techniques. The electrical conduc