Dispersal and sink pathways of suspended particulate matter from the orographically enhanced SWM regime of the SE Arabian Sea

The magnitude of precipitation plays an important role in the yield and supply of terrigenous matter into the sea through fluvial supply. The influence of climate on the influx of total suspended matter (TSM) into the continental margin of the SE Arabian Sea has been evaluated from subweekly synoptic variations in TSM and its advection rates, currents and winds during the southwest monsoon (SWM) and postmonsoon season. Our study endorses the high influx of TSM during the SWM (>82 mg l^?1; advection 26–110 mg m^?2 s^?1), albeit that most of it is sequestered into the shallow coastal region. Over the mid-outer shelf, there is uniformly low TSM (12–24 mg l^?1) and a weak TSM advection (9–4 mg m^?2 s^?1) throughout the year. This trend is persistent also in areas having upwelling-induced high marine productivity. We therefore surmise that higher fluvial influx and primary production during the SWM do not necessarily enhance the supply of particulate matter into the deeper offshore regions of the SE Arabian Sea. We ascribe a vital role to the prevailing morphodynamic processes.     

Characterization and transport of aerosols over the Bay of Bengal during the winter monsoon: a comparative study using in-situ and satellite measurements

Natural processes, such as dust storms and sea salt spray, and anthropogenic activities, such as the burning of fossil fuels and biomass, introduce aerosols into the atmosphere. Their concentration, geographic distribution and particle size promote significant climatic consequences. Aerosol transport processes, from landmasses to oceans, are scarcely understood because of inadequate in-situ observations. This study reports the results of spectral aerosol optical depth (AOD) measurements using a five-channel (380, 440, 500, 675 and 870 nm) handheld MICROTOPS Sun-photometer used during a sea-truth data collection campaign conducted in the central Bay of Bengal (BOB) during the northeastern monsoon period (10 November to 13 December 2007). For the entire cruise period, the mean values of the daily average of the AODs at 500 nm and 870 nm were 0.39 ± 0.065 and 0.22 ± 0.047, respectively, the mean value of the Angstrom exponent (α) was 1.23 ± 0.2 and the turbidity parameter (β) was 0.183 ± 0.044. A smaller α value together with a larger β value suggests the presence of an abundance of smaller aerosol particles near the coast. An air mass back-trajectory analysis was undertaken to identify the potential source regions of the aerosols. Analysis of the results demonstrated the effect of the aerosol transport and source regions on the spectral behaviour of the AODs. In-situ measured AOD (550 nm) and α (550 nm, 865 nm) values were further compared with Moderate Resolution Imaging Spectroradiometer (MODIS)-derived parameters. The in-situ and MODIS-derived AOD values were found to be in good agreement, with a coefficient of determination (R ²) of 0.78 and a standard error of 0.05, while the R ² for α was 0.68 with a standard error of 0.14.     

Moisture adsorption behaviour of esterified rubber wood (Hevea brasiliensis)

Hevea brasiliensis ) esterified with acetic anhydride, maleic anhydride and phthalic anhydride was studied for moisture adsorption behaviour. FTIR spectroscopic technique was used to analyse the chemical changes in the wood through the correspondent reactions. Spectra indicated increasing intensity of the C=O and C-O stretching bands, and reduction in O-H stretching vibrations that reflects formation of less hygroscopic ester bonds with hydroxyl groups of cell wall polymers. Moisture adsorption isotherms show low equilibrium moisture content in esterified wood at all relative humidity values as compared to a control. The adsorption data was analysed by applying Hailwood-Horrobin theory which separated the adsorbed water into hydrated water and dissolved water corresponding to mono-layer and multi-layer adsorption. Curve for M_h and M_s were similar in pattern for esterified wood and control with different magnitude. Low M_h and M_s in esterified wood indicate reduction in moisture adsorption sites. Inaccessible fraction of wood for water vapour was increased by 43%, 32% and 26% in acetic, maleic and phthalic anhydride treated wood, respectively, compared to the control. Acetic anhydride treatment was found most effective in reducing hygroscopicity of wood.

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Hevea brasiliensis ) wurde verestert mit Anhydriden der Maleins?ure, Essigs?ure und Phtals?ure. Das Adsorptionsverhalten bei verschiedenen Feuchten wurde mit FTIR-Methoden untersucht, um die entsprechenden chemischen Abl?ufe zu erfassen. Intensivere C=O, und -C-O- Streckschwingungen sowie reduzierte OH-Schwingungen reflektieren die neu gebildeten, weniger hygroskopischen Esterbindungen. Bei allen modifizierten Proben ergaben sich niedrigere Gleichgewichtsfeuchten. Die Adsorptions-Isothermen wurden mit Hilfe der Hailwood-Horrobin Theorie analysiert, um adsorbiertes (M_h) und gel?stes (M_s) Wasser zu unterscheiden. Der Kurvenverlauf für M_h und M_s für modifiziertes und unbehandeltes Holz war qualitativ ?hnlich, und unterschied sich nur quantitativ. Geringe Werte für M_h und M_s zeigen eine Verringerung der m?glichen Adsorptionsstellen an. Der nicht zug?ngliche Anteil des Holzes, bezogen auf Kontrollproben, verringerte sich auf 43% (Acetanhydrid), 32% (Maleins?ureanhydrid) und 26% (Phthals?ureanhydrid). Acetanhydrid erwies sich als das effektivste Mittel, um die Hygroskopizit?t zu erniedrigen.

     

The interaction of pulsed electric fields and texturizing ‐ antifreezing agents in quality retention of defrosted potato strips

The combination of pulsed electric fields (PEF) and texturizing and antifreeze agents on quality retention of defrosted potato strips were studied. Potato strips (10 mm thickness, 100 g) were placed in different solutions (1% w/v) of CaCl₂, glycerol, trehalose as well as NaCl and sucrose, treated with PEF (0.5 kV cm^?1, 100 pulses, 4 Hz). Then, all the samples were soaked in the same solutions for 10 min. After draining, samples were packed into polypropylene pouches and stored at ?18 °C for 12 h. Samples were thawed out at room temperature (20 °C) in 3 h. Untreated controls and PEF treated control samples were also frozen and thawed in similar conditions. To assess the potato strip quality, the thawed samples were analysed for moisture content, weight loss, firmness and colour attributes. The results indicate that PEF treatment by itself is not a suitable pre‐treatment method for frozen potato strips and should be assisted by CaCl₂ and trehalose treatment to prevent softening after defrosting. Firmness analyses determined that application of PEF alone results in 2.38 N. However, PEF in combination with CaCl₂ and trehalose result in 2.97 N and 2.99 N, respectively, which are both significantly firmer than the samples solely treated with PEF. CaCl₂ and trehalose were effective in not only maintaining the structural integrity of the cells, but also retaining colour attributes. The L* value was found to be higher (P < 0.05) in CaCl₂ and trehalose treated samples (58.95 and 57.21, respectively), as compared to PEF treated samples (53.97) denoting a darker colour. Application of CaCl₂ and trehalsoe in combination with PEF also resulted in significantly less weight loss after thawing.     

Light-assisted adsorption processes in nanocrystalline diamond membranes studied by femtosecond laser spectroscopy

We report on femtosecond photoluminescence spectroscopy of nanocrystalline diamond membranes (thickness ～ 1000 nm) prepared by microwave plasma enhanced chemical vapour deposition (CVD) technique. The decay of photoluminescence excited by the blue femtosecond light pulses (405 nm) reflects the photoexcited charge carrier dynamics in the sub-band gap energy states. The photoluminescence is strongly influenced by ambient conditions and by the laser irradiation (405 nm, 70 fs pulses). Under lower ambient air pressure (5–300 Pa) the photoluminescence intensity increases and the photoluminescence decay gets faster. For higher air pressures (> 600 Pa) the photoluminescence intensity decreases and the photoluminescence decay rates do not evolve. We interpret the observed different behaviour of the photoluminescence in the two air pressure intervals in terms of a thin water layer condensed on the surface at higher air pressures. Due to a low coverage of the sample surface by water molecules under low pressure the air species can be adsorbed to NCD and influence the sub-band gap energy states.     

Features of compacting hydrogen-doped granules of a VT5-1kt titanium alloy

The effect of hydrogen on consolidation of granules of the VT5-1kt alloy, as well as the structure, mechanical characteristics, and fracture micromechanism of a compact produced by the hot-isostatic-pressing technique, is studied. It is established that hydrogen doping allows obtainment of a compact of the VT5-1kt alloy of 100% density with a high complex of properties in the course of a few minutes at such temperature-strength conditions in which the consolidation of granules is not realized. It is shown that the process of consolidation of hydrogenated granules proceeds more effectively in the (α + β) region.     

Space charge limited currents in chlorazole black E dye

Space-charge-limited-currents have been studied in Chlorazole Black E (CBE) dye to understand the current-voltage relationship and the nature and distribution of traps present in the dye. Three distinct regions of voltage-current characteristics have been observed probably for the first time. The results have been discussed on the basis of carrier injection theory. There are non-uniformly distributed deep as well as shallow traps.     

Oxidation of polycyclic aromatic hydrocarbons with hydrogen peroxide catalyzed by Iron(III)porphyrins

A variety of iron-metallated functional porphyrins have been synthesized and their catalytic activity to oxidize polycyclic aromatic hydrocarbons, (PAHs) using hydrogen peroxide as oxidant was investigated. It was found that iron-metallated porphyrins bearing strong electronegative groups at β-pyrrolic positions show an exceptionally high catalytic efficiency.     

Biogenic synthesis and thermo‐magnetic study of highly porous carbon nanotubes

Nanomaterials synthesis using natural sources is the technology to up come with advanced materials through extracts of plant, microorganisms, poultry waste etc. In this study, the authors report the synthesis of porous carbon nanotubes using high‐temperature decomposition technique facilitated by cobalt salt using chicken fats, a poultry waste as a precursor. Since chicken fats contain fatty acids which can decompose into short hydrocarbon chains and cobalt can act as the catalyst. The formation of carbon nanotubes was confirmed by Raman spectra, peaks at 1580 and 1350.46 cm⁻¹ confirmed the graphite mode G‐band and structural imperfections defect mode D‐band, respectively. Transmission electron microscopy showed the formation of tube‐like structures. Nitrogen adsorption–desorption studies showed the high‐surface area of 418.1 m² g⁻¹ with an estimated pore diameter of 8.1 nm. Thermogravimetry analysis–derivative thermogravimetric analysis–differential thermal analysis showed the instant weight loss at 517°C attributed to the rapid combustion of nanotubes. A vibrating‐sample magnetometer showed the paramagnetic nature of the so‐formed carbon nanotubes formed.Inspec keywords: transmission electron microscopy, infrared spectra, nanomagnetics, pyrolysis, decomposition, adsorption, desorption, carbon nanotubes, differential thermal analysis, thermal analysis, nanofabrication, Raman spectra, X‐ray diffraction, scanning electron microscopy, paramagnetic materialsOther keywords: biogenic synthesis, highly porous carbon nanotubes, microorganisms, high‐temperature decomposition technique, cobalt salt, chicken fats, fatty acids, short hydrocarbon chains, Raman spectra, graphite mode G‐band, structural imperfections defect mode D‐band, transmission electron microscopy, paramagnetic nature, thermo‐magnetic properties, poultry waste, nitrogen adsorption‐desorption studies, thermogravimetry analysis, differential thermal analysis, carbon nanotubes, temperature 517.0 degC, C