Acoustic study of nano-crystal embedded PbO-P2O5 glass

Nano-crystal embedded PbO-P₂O₅ glass has been prepared and characterized by XRD and TEM measurements. The ultrasonic velocity and attenuation measured within the temperature range 80–300 K show significant structure and interesting feature with the presence of nano-crystalline region. The glass samples were prepared by melt-quench method and nano-crystals of different sizes were produced by heat treatment of the glasses for different durations of heating. All the processes were carried out at or above glass transition temperature. A theoretical model that takes account of the effects of thermally activated relaxation, anharmonicity as well as microscopic elastic inhomogeneities arising out of fluctuations has been successfully applied to interpret the variation of ultrasonic velocity and attenuation data. An interesting outcome of this application has been to propose a method for the determination of the size of nano-crystals from the ultrasonic attenuation data.     

In-house contamination of potable water in urban slum of Kolkata, India: a possible transmission route of diarrhea

We have investigated and determined the potentiality of different water sources, both for drinking and domestic purposes, in diarrheal disease transmission in diarrhea endemic foci of urban slums in Kolkata, India in a one and half year prospective study. Out of 517 water samples, collected from different sources, stored water (washing) showed higher prevalence of fecal coliforms (58%) (p < 0.0001) in comparison with stored (drinking) samples (28%) and tap/tubewell water (8%) respectively. Among different sources, stored water (washing) samples had the highest non-permissible range of physico-chemical parameters. Fecal coliform levels in household water containers (washing) were comparatively high and almost 2/3 of these samples failed to reach the satisfactory level of residual chlorine. Interestingly, 7% stored water (washing) samples were found to be harboring Vibrio cholerae Improper usage of stored water and unsafe/poor sanitation practices such as hand washing etc. are highlighted as contributory factors for sustained diarrheal episodes. Vulnerability of stored water for domestic usage, a hitherto unexplored source, at domiciliary level in an urban slum where enteric infections are endemic, is reported for the first time. This attempt highlights the impact of quality of stored water at domiciliary level for fecal-oral contamination vis-à-vis disease transmission.     

An improved microfluidics approach for monitoring real-time interaction profiles of ultrafast molecular recognition

Our study illustrates the development of a microfluidics (MF) platform combining fluorescence microscopy and femtosecond/picosecond-resolved spectroscopy to investigate ultrafast chemical processes in liquid-phase diffusion-controlled reactions. By controlling the flow rates of two reactants in a specially designed MF chip, sub-100 ns time resolution for the exploration of chemical intermediates of the reaction in the MF channel has been achieved. Our system clearly rules out the possibility of formation of any intermediate reaction product in a so-called fast ionic reaction between sodium hydroxide and phenolphthalein, and reveals a microsecond time scale associated with the formation of the reaction product. We have also used the developed system for the investigation of intermediate states in the molecular recognition of various macromolecular self-assemblies (micelles) and genomic DNA by small organic ligands (Hoechst 33258 and ethidium bromide). We propose our MF-based system to be an alternative to the existing millisecond-resolved "stopped-flow" technique for a broad range of time-resolved (sub-100 ns to minutes) experiments on complex chemical∕biological systems.     

Urinary albumin and IgG levels of sea level and moderate altitude dwellers under high altitude stress

Studies have been made on albumin and IgG levels in the early morning urine (EMU) specimens of male Indians under high altitude stress. Albumin level increased significantly in both the category of the subjects under high altitude stress. On return of the subjects from high altitude to their respective base conditions of lower altitudes, urinary albumin levels reverted to the original values. Only a small amount of IgG was detected in the EMU of both the category of the subjects at high altitude, whereas no detectable IgG level was found in both groups in their respective original conditions.     

A probabilistic analysis of two university parking issues

The uncertain nature of the demand for university parking has now created a major problem for university planners. From a facilities planning perspective, it is important to comprehend the probabilistic nature of the demand for parking and parking rules violations. Given this background, in our note, we shed light on two insufficiently studied issues concerning university parking. First, we focus on short-term and long-term parkers. We determine the mean parking time of an arriving car and then we compute the probability distribution function of the number of occupied parking spots at any particular time. Second, we concentrate on parking rules violators and we calculate the probability distribution function of the number of violators who are fined at an inspection.     

Price competition, pollution, and environmental policy in an open economy

We study three issues about environmental policy in a two country world in which national governments and polluting firms act strategically. First, we examine the conditions under which the pursuit of unilateral environmental policy by a country in a setting in which polluting firms play a price leadership game, will make that country worse off. Second, we study the results of environmental regulation by means of alternate price control instruments when national governments care about international pollution, but polluting firms that play a price leadership game, do not. Third, we compare our findings with the corresponding results when polluting firms play a quantity leadership (Stackelberg) game. We find that there are plausible theoretical and hypothetical numerical circumstances in which the pursuit of unilateral environmental policy is welfare reducing. We show that the use of a trade policy instrument to control pollution is generally dominated by the other price instruments that we analyze. Finally, if the two national governments are able to compel the polluting firms to choose between prices and quantities, then, generally speaking, they should require the two firms to choose quantities rather than prices. Received: August 1999/Accepted: January 2000     

Vertically aligned ZnO nanowire arrays in Rose Bengal-based dye-sensitized solar cells

We fabricate dye-sensitized solar cells (DSSC) using vertically oriented, high density, and crystalline array of ZnO nanowires, which can be a suitable alternative to titanium dioxide nanoparticle films. The vertical nanowires provide fast routes or channels for electron transport to the substrate electrode. As an alternative to conventional ruthenium complex, we introduce Rose Bengal dye, which acts as a photosensitizer in the dye-sensitized solar cells. The dye energetically matches the ZnO with usual KII₂ redox couple for dye-sensitized solar cell applications.     

Hierarchical assembly of carbon nanotubes-liquid crystal nanocomposite

Fabrication of liquid crystalline (LC) nanomaterials in an aligned pattern along the multiwalled carbon nanotubes (CNT) has been reported here. The nanocomposite was prepared by sonicating esterified CNTs and the ferroelectric liquid crystal (FLC) in chloroform. The nanohybrid shish kebab (NHSK) like pattern was observed in SEM analysis. The nanocomposite materials were characterized by Fourier transform infrared spectroscopy (FTIR), polarizing optical microscopy and electron microscopy. The DC and AC electrical properties of the composite materials were investigated. The DC conductivity of the nanocomposite increased by 2 order from the FLC materials and AC relaxation has been observed, in the nanocomposite, which was totally absent in the FLC materials.     

Game models of environmental policy in an open economy

In this paper we study some aspects of the question of international environmental regulation from a game theoretic perspective. We address two broad questions. First, we examine the circumstances under which the pursuit of unilateral environmental policy by a country in a Stackelberg game, will make that country worse off. Second, we study the effects of environmental regulation by means of alternate price control instruments in a Stackelberg game when there is transboundary pollution. We find that there are plausible theoretical circumstances in which the pursuit of unilateral environmental policy is not a good idea. Further, we show that in choosing between alternate pollution control instruments, national governments typically face a tradeoff between instruments which correct more distortions but are costly to implement and instruments which correct fewer distortions but are less costly to implement. In particular, we obtain a dominance result for a tariff policy; this result favors the use of tariffs from an informational standpoint alone.I thank Peter Berck and Larry Karp for their input; I alone am responsible for the output. This research has been supported by the USDA and the Giannini Foundation.     

Studies of blood pH and blood gases of humans under moderate and high altitude stress: effect of acetazolamide supplementation

Studies have been carried out on blood pH, Pco2, Po2, (HCO‐3), sodium and potassium levels of 30 human subjects at a moderate and at a high altitude in the north eastern Himalayan range. Blood pH was found to be increased, whereas Po2 and PCo2 levels decreased appreciably under high altitude stress. However, no significant change was observed in plasma bicarbonate level. Plasma sodium level was found to be lowered, while that of potassium level was raised at high altitude in comparison to the moderate altitude. Treatment with acetazolamide was found to be effective in lowering blood pH, Pco2 (HCO‐3) and plasma potassium level at high altitude, while PO2 level increased in comparison to the placebo group. On return of the subjects from high to moderate altitude, the studied parameters reverted to the initial moderate altitude base data.