Organic and inorganic markers and stable C-, N-isotopic compositions of tropical coastal aerosols from megacity Mumbai: sources of organic aerosols and atmospheric processing

To better understand the sources of PM10 samples in Mumbai, India, aerosol chemical composition, i.e., total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions were studied together with specific markers such as methanesulfonate (MSA), oxalic acid (C-2), azelaic acid (C-9), and levoglucosan. The results revealed that biofuel/biomass burning and fossil fuel combustion are the major sources of the Mumbai aerosols. Nitrogen-isotopic (delta N-15) composition of aerosol total nitrogen, which ranged from 18.1 to 25.4 %, also suggests that biofuel/biomass burning is a predominate source in both the summer and winter seasons. Aerosol mass concentrations of major species increased 3-4 times in winter compared to summer, indicating enhanced emission from these sources in the winter season. Photochemical production tracers, C-2 diacid and nssSO(4)(2-), do not show diurnal changes. Concentrations of C-2 diacid and WSOC show a strong correlation (r(2) = 0.95). In addition, WSOC to OC (or TC) ratios remain almost constant for daytime (0.37 +/- 0.06 (0.28 +/- 0.04)) and nighttime (0.38 +/- 0.07 (0.28 +/- 0.06)), suggesting that mixing of fresh secondary organic aerosols is not significant and the Mumbai aerosols are photochemically well processed. Concentrations of MSA and C-9 diacid present a positive correlation (r(2) = 0.75), indicating a marine influence on Mumbai aerosols in addition to local/regional influence. Backward air mass trajectory analyses further suggested that the Mumbai aerosols are largely influenced by long-range continental and regional transport. Stable C-isotopic ratios (delta C-13) of TC ranged from -27.0 to -25.4 %, with slightly lower average (-26.5 +/- 0.3 %) in summer than in winter (-25.9 +/- 0.3 %). Positive correlation between WSOC/TC ratios and delta C-13 values suggested that the relative increment in C-13 of wintertime TC may be caused by prolonged photochemical processing of organic aerosols in this season. This study suggests that in winter, the tropical aerosols are more aged due to longer residence time in the atmosphere than in summer aerosols. However, these conclusions are based on the analysis of a limited number of samples (n = 25) and more information on this topic may be needed from other similar coastal sites in future

Crystal fields and second-order magnetic hyperfine interactions in TmFe<SUB>2</SUB>Si<SUB>2</SUB>

We report the measurement of Mossbauer hyperfine spectra of TmFe<SUB>2</SUB>Si<SUB>2</SUB> using the 8.4 keV transition in <SUP>169</SUP>Tm. The detailed temperature dependence of the quadrupole interaction has permitted us to evaluate the crystalline electric fields (CEF) acting on Tm atom. The analysis indicates the ground state of Tm to be a singlet state. However, the hyperfine coupling of the <SUP>169</SUP>Tm with the excited CEF states generates a second order magnetic hyperfine interaction which has been observed in our experiment. An account of the spin relaxation of the second-order magnetic hyperfine interaction is presented

Synthesis and electrical properties of mixed tetrahedral cluster phases, A(Mo<SUB>2</SUB>Re<SUB>2</SUB>)S<SUB>8</SUB>, A=Fe,Ni,Zn,Cu and Ga

Quaternary phases, A(Mo<SUB>2</SUB>Re<SUB>2</SUB>)S<SUB>8</SUB>, A=Fe,Ni,Zn,Cu and Ga containing mixed tetrahedral (Mo<SUB>2</SUB>Re<SUB>2</SUB>) clusters have been synthesized and electrical properties examined in the range 77-300K. The compounds possess cubic symmetry and are n-type semiconductors except when A=Cu, which is metallic exhibiting p-type behavior. Isostructural GaMo<SUB>4</SUB>S<SUB>8</SUB> is an n-type semiconductor. The type of bonding in these materials is discussed

Electronic properties of Chevrel phases by positron angular correlation

A comparative study of the Chevrel phases Mo<SUB>6</SUB>S<SUB>8</SUB>, Mo<SUB>6</SUB>Se<SUB>8</SUB>, PbMo<SUB>6</SUB>S<SUB>8</SUB> and Cu<SUB>1.8</SUB>Mo<SUB>6</SUB>S<SUB>8</SUB> is made by the positron angular correlation technique at room temperature. Electronic properties like the number of conduction electrons per cluster, the density of states at the Fermi level, the electron effective masses and the Fermi velocities are obtained within the framework of the free electron model. The results are discussed in terms of available theoretical and other experimental data

The association of hand and wrist injuries with other injuries in multiple trauma patients. A retrospective study in a UK Major Trauma Centre

Background: Approximately 20,000 major trauma cases occur in England every year. However, the association with concomitant upper limb injuries is unknown. This study aims to determine the incidence, injury pattern and association of hand and wrist injuries with other body injuries and the Injury Severity Score (ISS) in multiply injured trauma patients. Methods: Single centre retrospective study was performed at a level-one UK Major Trauma Centre (MTC). Trauma Audit and Research Network (TARN) eligible multiply injured trauma patients that were admitted to the hospital between January 2014 and December 2018 were analysed. TARN is the national trauma registry. Eligible patients were: a trauma patient of any age who was admitted for 72 hours or more, or was admitted to intensive care, or died at the hospital, was transferred into the hospital for specialist care, was transferred to another hospital for specialist care or for an intensive care bed and whose isolated injuries met a set of criteria. Data extracted included: age, gender, mode of arrival, location of injuries including: hand and/or wrist and mechanism of injury. We performed a logistic regression analysis to assess the association between hand/wrist injury to ISS score of 15 points or above/below and to the presentation of other injuries. Results: 107 patients were analysed. Hand and wrist injuries were the second most common injury (26.2%), after thoracic injuries. Distal radial injuries were found in 5.6%, carpal/carpometacarpal in 6.5%, concurrent distal radius and carpometacarpal in 0.9%, phalangeal injuries in 4.7%, tendon injuries in 0.9% and concurrent hand and wrist injuries in 7.5% cases. There was a significant association between hand or wrist injuries and lower limb injuries (Odds Ratio (OR): 3.84; 95% confidence intervals (CI): 1.09 to 13.50; p=0.04) and pelvic injuries (OR: 4.78; 95% CI: 1.31 to 17.44; p=0.02). There was no statistical association between hand and wrist injuries and ISS score (OR: 0.80; 95% CI: 0.11 to 5.79; p=0.82). Conclusions: Hand and wrist injuries are prevalent in trauma patients admitted to MTCs. They should not be under-estimated but routinely screened for in multiply injured patients particularly those with a pelvic or lower limb injury