Physico-Chemical Studies on Dusts: The Suppression of Airborne Dust by Aqueous Sprays

This study is concerned with the capture of airborne dust particles by sprayed liquid droplets, with particular reference to the airborne coal dust encountered in mining practice. The particle size range 0.5-5.0 microns, of physiological importance in causing occupational health hazard, has been investigated. The significance of duets and their harmful particle-size and concentration are discussed and the incidences of coal-miners' pneumoconiosis and existing methods of dust suppression in mines are surveyed. The general mechanism of liquid spray formation from nozzles is investigated and the theoretical probability of capture of dust particles by spray droplets is discussed. Experiments on dust suppression were carried out on moving dust clouds in a wind-tunnel of 45.72 cm. (18 in.) diameter and 20 metres (65 ft.) long, under controlled conditions. Dust clouds, of concentrations in the range 300 and 3000 p.p.c.c., were produced using Hattersley'a laboratory type dust generator. A three-throw reciprocating pump provided spray pressures up to about 210 kg./sq. cm. (3,000 p s i.g.) and the spray nozzles were operated at the axis of the tunnel against the flow of dust-laden air. Simultaneous dust sampling was done by two thermal precipitators located ahead of and beyond the spray nozzle. Distribution of air velocity in the tunnel was studied and modifications in the tunnel were made to straighten out the air flow. The effect on air flow pattern of baffle plates suitably placed in the tunnel is illustrated in the form of iso-velocity curves. Distribution of dust concentration In the tunnel was studied with salicylic acid filters and the rate of decay of dust concentration with distance along the tunnel was found to be constant . The probable mechanisms of dust fall-out are discussed. A system for counting the thermal precipitator dust slides using a five-channel Automatic Particle Counter and Sizer was developed and an analysis of variance for the machine was made. Simultaneous dust sampling by thermal precipitator and salicylic acid filter was carried out in the tunnel and a correlation factor was derived on the basis of proportional number percentage size frequencies in both the samples. Measurment of Average Droplet Size was carried out for water sprays in the range 35.15-190.16 kg./sq. cm. (500-2,750 p.s.i.g) using a solid cone spray nozzle and the relationship A.D.S a p(-0.28) was obtained. A functional non-dimensional relationship was also derived between the characteristics of the spray and the Average Droplet Size. The dust suppression work was mainly concerned with small high pressure spray nozzles and the following issues were brought to focus: The effects on the efficiency of dust suppression of, (a) hollow cone and solid cone spraying, (b) high spray pressures, (c) surface tension of sprayed liquid, (d) counterflow air velocity, and (e) a tandem arrangement of spray nozzles. The effect of spray throughput on dust-water ratio was also studied. Solid cone spraying was found to be about 5 per cent more efficient than the hollow cone spray for the same nozzle. Maximum dust suppression was effected at 140.6 kg./sq. cm. in both the cases. (53.58% and 48.5%). Surface active agent solutions were found to give only a small increase in dust suppression efficiency, E. The wetting power of different types of surface active agents is discussed. A relationship was obtained between the efficiency, spray pressure and the surface tension of the sprayed liquid. Tandem spraying was found to give the best dust suppression efficiencies without much increase in water throughput. The rate of increase in E with number of spray nozzles in tandem was found to be maximum (about 6.5%) at 140.6 kg./sq. cm. An increase in air velocity resulted in a rapid decrease of E. The rapid deceleration of droplets on discharge into the gaseous medium, its lowered efficacy of impact on dust particles and the consequent reduction of the "capture cross-section" are discussed. The dust-water ratio was calculated for all spray pressures and nozzles employed and was found to generally decrease with increase in throughput. The sprayed droplets did not appear to be selective in suppressing any particular size range of dust particles. An improved type of dust feeding machine was put into operation and is discussed in the Appendix

Ab Initio Studies on Hematite Surface and the Adsorption of Phosphate

This investigation explores the ab initio DFT method for understanding surface structure of hematite and the nature and energetics of phosphate adsorption. Using the full potential linearized plane wave method (FP-LAPW), we derived the structure and energies of various magnetic forms of hematite. The antiferromagnetic (AFM) form was observed to be the most stable. Hematite surfaces with Fe-termination, O-termination, or OH-termination were studied. The OH-terminated surface was the most stable. Stability of hematite surfaces follows the order OH-termination &gt; Fe-termination &gt; O-termination. Thus, surface reaction with hematite would occur with the OH at the surface and not with Fe atoms. The structure of phosphate adsorbed on hematite was derived. Bonding is through the H atom of the OH at the surface. An alternative mechanism of phosphate adsorption on hematite has been derived. Adsorption energy is high and suggests chemisorption rather than physisorption of phosphate on hematite.</jats:p

Stability of the coastline from Manakkodam to Thottappally along the Kerala coast

Wave refraction studies were undertaken to assess the stability of the coastline from Manakkodam to Thottappally, along the Kerala coast. Refraction diagrams were constructed for waves of different periods and directions of approach and the cumulative effect of the sediment transport was assessed for the particular region under study. The study reveals that the coastline north of Alleppey is on the whole a stable one. The stability of the beaches on the southern side from Alleppey Pier to Thottappally spillway, is more dependent on the changes in offshore relief

THE CASE OF THE EARLY POETRY

The creation of poetry works for poets is by given the freedom to use the language (licencia poeitica). However, the freedom to use language can be interpreted for people who are already proficient in the rules and meaning of language. For beginner poets the use of poetic lyses is sometimes inappropriate. Instead, they tend to display their inability to use language. This is what the authors found in the poetry anthology of the beginner writers who became the main background in this study. This is a qualitative research and used purposive sampling. This research took the object of 650 poems from 91 writers who were compiled in 7 anthologies of poetry writing to see the case found in their poems as an illustration of the misunderstanding of poetry creation. The data collection techniques used in this study was observation and document study. The writer used Spiral Model data analysis techniques for this research. The results of this research found that a) the meaning transparency or message b) language rules such as the use of capital letters with punctuation c) unity of ideas in the verse d) consideration of building typography e) beheadings

Transmission dynamics of methicillin-resistant Staphylococcus aureus in a medical intensive care unit in India

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a global pathogen and an important but seldom investigated cause of morbidity and mortality in lower and middle-income countries where it can place a major burden on limited resources. Quantifying nosocomial transmission in resource-poor settings is difficult because molecular typing methods are prohibitively expensive. Mechanistic statistical models can overcome this problem with minimal cost. We analyse the transmission dynamics of MRSA in a hospital in south India using one such approach and provide conservative estimates of the organism's economic burden. Methods and Findings: Fifty months of MRSA infection data were collected retrospectively from a Medical Intensive Care Unit (MICU) in a tertiary hospital in Vellore, south India. Data were analysed using a previously described structured hidden Markov model. Seventy-two patients developed MRSA infections and, of these, 49 (68%) died in the MICU. We estimated that 4.2% (95%CI 1.0, 19.0) of patients were MRSA-positive when admitted, that there were 0.39 MRSA infections per colonized patient month (0.06, 0.73), and that the ward-level reproduction number for MRSA was 0.42 (0.08, 2.04). Anti-MRSA antibiotic treatment costs alone averaged $124/patient, over three times the monthly income of more than 40% of the Indian population. Conclusions: Our analysis of routine data provides the first estimate of the nosocomial transmission potential of MRSA in India. The high levels of transmission estimated underline the need for cost-effective interventions to reduce MRSA transmission in hospital settings in low and middle income countries

Production and evaluation of potassium fertilizers from silicate rock

Rising price and limited geographical availability of traditional sources of potassium (K) fertilizers have stimulated a search for alternative K sources in different parts of the world. We evaluated mineral transformations and agronomic properties of an alternative source of K produced through thermal and chemical treatment of the verdete rock (VR). Chemical and mineralogical characteristics were evaluated before and after each treatment. Four K sources (verdete rock, KCl, acidified verdete, and calcinated verdete) were applied to a Typic Hapludox at different rates. Eucalyptus and sequentially cropped maize and grass were grown in the treated soils. Ver- dete rock, which contained glauconite and microcline as K crystalline minerals, had very low solubility in water and in citric acid. Thermal and chemical treatments increased the concentration of water soluble K and citric acid soluble K. These treatments also caused crystalline K minerals to collapse and form sylvite and arcanite. Untreated verdete rock was not suitable as a K source for maize (Zea mays L.) and eucalyptus (Eucaliptus urograndis I144). Thermal and chemical treatments increased agronomic performance of VR to be similar to KCl. When K was applied as K-calcined verdete, 82% of the total K was recovered in maize and grass cultivations. Less K was recovered in plant following addition of K-acidified verdete and KCl (72% and 77%, respectively). Potassium recoveries by eucalyptus were about 52, 53, and 60% of the amount applied of calcined verdete, acidified verdete, and KCl, respectively. Both calcination and thermal treatment increased the K uptake and dry matter production for all plant species tested to be similar to KCl suggesting that this silicate rock could be beneficiated to be an effective K fertilizer

Injection of oxygenated Persian Gulf Water into the southern Bay of Bengal

Persian Gulf Water (PGW) is an oxygenated, high-salinity water mass that has recently been detected in the Bay of Bengal (BoB). However, little is known about the transport pathways of PGW into the BoB. Ocean glider observations presented here demonstrate the presence of PGW in the southwestern BoB. Output from an ocean reanalysis product shows that this PGW signal is associated with a northward-flowing filament of high-salinity water. Particle tracking experiments reveal two pathways: one in the eastern Arabian Sea that takes a minimum of 2 years and another in the western Arabian Sea that takes a minimum of 3 years. The western pathway connects to the BoB via equatorial currents. The greatest influx of PGW occurs between 82° and 87°E during the southwest monsoon. We propose that injection of PGW to the BoB oxygen minimum zone (OMZ) contributes to keeping oxygen concentrations in the BoB above the level at which denitrification occurs

Organic matter quality and dynamics in tropical soils amended with sugar industry residue

Soil organic matter depletion caused by agricultural management systems have been identified as a critical problem in most tropical soils. The application of organic residues from agro-industrial activities can ameliorate this problem by increasing soil organic matter quality and quantity. Humic substances play an important role in soil conservation but the dynamics of their transformations is still poorly understood. This study evaluated the effect of compost application to two contrasting tropical soils (Inceptisol and Oxisol) for two years. Soil samples were incubated with compost consisting of sugarcane filter cake, a residue from the sugar industry, at 0, 40, 80, and 120 Mg ha-1. Filter cake compost changed the humic matter dynamics in both content and quality, affecting the soil mineralogical composition. It was observed that carbon mineralization was faster in the illite-containing Inceptisol, whereas humic acids were preserved for a longer period in the Oxisol. In both soils, compost application increased fulvic acid contents, favoring the formation of small hydrophilic molecules. A decrease in fluorescence intensity according to the incubation time was observed in the humic acids extracted from amended soils, revealing important chemical changes in this otherwise stable C pool