Chemical Conformation Induced Transport Carrier Switching in Molecular Junction based on Carboxylic-Terminated Thiol Molecules.

The paper demonstrates the effect of the chemical conformation of the -COOH group on the transport characteristic including conductance, rectification, and length effect in molecular junctions (MJs) formed by self-assembled monolayers of carboxylic-terminated thiol molecules. For an alkyl chain shorter than C11, the transport mechanism was attributed to a direct off-resonant tunneling of a hole carrier, located at the Au-S interface, whereas a hopping mechanism was assigned to the alkyl chain longer than the C11 chain located at the -COOH group. The hopping mechanism may be operated by electron transport associated with the breaking of the -OH bonding likely driven by a voltage. Importantly, at the C11 alkyl chain, we observed that the transport carrier operating in MJs could change from a hole carrier into an electron carrier. The result strongly proves that the chemical conformation should be considered in analyzing molecular electronics and provides a basis for the rational design of molecular electronic devices.

Factors associated with HIV RNA viral loads in ART-naïve patients: implications for treatment as prevention in concentrated epidemics.

BACKGROUND: Limited data are available on factors associated with HIV-RNA viral load (VL) among antiretroviral treatment (ART)-naïve key populations in concentrated epidemics. METHODS: We conducted a cross-sectional survey of 1211 adult ART-naïve patients at 19 HIV clinics in Ho Chi Minh City (HCMC), Vietnam. Data collection included a standardised questionnaire, routine laboratory testing, hepatitis serology and HIV VL. Correlation between CD4 cell count and VL was assessed across all participants. In 904 participants not meeting Vietnam criteria for ART (CD4 cell count >350 cells/mm(3), WHO clinical stage 1 or 2 and not pregnant), multivariate analyses were conducted to assess factors associated with HIV VL. RESULTS: Pre-ART patients had a median age of 31 years and 54% were male. Median CD4 cell count was 533 cells/mm(3). Median HIV VL was 17,378 copies/mL; 60% had VL greater than 10,000 copies/mL and 16% had VL above 100,000 copies/mL. Although declining CD4 cell count was correlated with rising VL across all CD4 cell counts, correlation of VL with CD4 cell counts between 351 and 500 cell/mm(3) was not significant. On multivariate linear regression, higher HIV VL was independently associated with male sex, men who have sex with men (MSM), CD4 cell count 351-500, HIV diagnosis within the previous 6 months, and hepatitis B (HBV). Lower HIV VL was independently associated with hepatitis C (HCV). CONCLUSIONS: The majority of HIV patients who were not eligible for ART in HCMC in 2014 had HIV VL greater than 10,000 copies/mL. These data support expanded eligibility of ART to all HIV patients with the goal of treatment as prevention. This study is also among the first to demonstrate that MSM had a higher VL than women and heterosexual men and highlights the need for improved outreach and linkages to HIV care for this high-risk group.

Effects of chloride and sulfate on the rate of oxidation of ferrous ion by H2O2.

The rates of oxidation of Fe(II) by H(2)O(2) in the presence of sodium perchlorate, sodium nitrate, sodium chloride and sodium sulfate salts (0-1M) have been compared in the study. Experiments were carried out in a batch reactor, in the dark, at pH <3, 25+/-0.5 degrees C and at controlled ionic strength (< or =1M). The experimental results showed that the rates of oxidation of Fe(II) in the presence of chloride, nitrate and perchlorate were identical. In the presence of sulfate, the rate of oxidation of Fe(II) was faster and depended on the pH and the concentration of sulfate. The pseudo second-order rate constants for the reaction of H(2)O(2) with Fe(2+), FeCl(+) and FeSO(4) were determined as 55+/-1, 55+/-1 and 78+/-3 M(-1) s(-1), respectively.