Hydrogen peroxide (H(2)O(2)) is an important atmospheric oxidant that can serve as a sensitive indicator for HO(x) (OH + HO(2)) chemistry. We report the first direct experimental determination of the uptake coefficient for the heterogeneous reaction of gas-phase hydrogen peroxide (H(2)O(2)) with titanium dioxide (TiO(2)), an important component of atmospheric mineral dust aerosol particles. The kinetics of H(2)O(2) uptake on TiO(2) surfaces were investigated using an entrained aerosol flow tube (AFT) coupled with a chemical ionization mass spectrometer (CIMS). Uptake coefficients (gamma(H(2)O(2))) were measured as a function of relative humidity (RH) and ranged from 1.53 x 10(-3) at 15% RH to 5.04 x 10(-4) at 70% RH. The observed negative correlation of RH with gamma(H(2)O(2)) suggests that gaseous water competes with gaseous H(2)O(2) for adsorption sites on the TiO(2) surface. These results imply that water vapor plays a major role in the heterogeneous loss of H(2)O(2) to submicrometer TiO(2) aerosol. The results are compared with related experimental observations and assessed in terms of their potential impact on atmospheric modeling studies of mineral dust and its effect on the heterogeneous chemistry in the atmosphere.

With the aim to capture and subsequent selective trapping of CO2, a nanocomposite has been developed through selective modification of the outer surface of the halloysite nanotubes (HNTs) with an organosilane to make the nanocomposite a novel solid-phase adsorbent to adsorb CO2 from the atmosphere at standard ambient temperature and pressure. The preferential adsorption of three major abundant isotopes of CO2 (12C16O2, 13C16O2, and 12C16O18O) from the ambient air by amine functionalized HNTs has been explored using an optical cavity-enhanced integrated cavity output spectroscopy. CO2 adsorption/desorption cycling measurements demonstrate that the adsorbent can be regenerated at relatively low temperature and thus, recycled repeatedly to capture atmospheric CO2. The amine grafted halloysite shows excellent stability even in oxidative environments and has high efficacy of CO2 capture, introducing a new route to the adsorption of isotope selective atmospheric CO2.

The first direct laboratory measurements of gaseous hydrogen peroxide uptake by authentic Gobi and Saharan dust aerosol particles as a function of relative humidity (RH) have been carried out in an entrained aerosol flow tube coupled to a chemical ionization mass spectrometer. Gobi dust shows uptake coefficients, γ_{H2 O2} = (3.33±0.26) ×10⁻⁴ at 15% RH rising to γ_{H2 O2} = (6.03±0.42) ×10⁻⁴ at 70% RH; the corresponding values for Saharan dust are systematically higher (γ_{H2 O2} = (6.20±0.22)×10⁻⁴ at 15% RH rising to γ_{H2 O2} = (9.42±0.41) ×10⁻⁴ at 70% RH). High resolution X-ray photoelectron spectroscopy (XPS) measurements of the surface chemical composition of the two mineral dust samples together with published water adsorption isotherms of their principal constituents enables rationalization of these observations, which are relevant to nighttime tropospheric chemistry. A box model study performed by incorporating the experimentally determined data set reveals that uptake of H₂O₂ onto dust can be an important loss process for this species which has been, until now, poorly constrained

A high frequency of HBV infection was seen using molecular methods in thalassemic patients. The frequency of infection was similar in vaccine responders and non-responders. A number of mutations were observed in the S gene, which could have implications for viral replication as well as virus-host cell interaction.