Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 36
Filtrar
1.
Int J Biol Macromol ; 248: 125936, 2023 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-37482156

RESUMO

The present study aimed to produce, characterize, and apply pullulanase from Aspergillus flavus (BHU-46) for fruit juice processing, assessing its enzymatic properties and impact on juice quality. Pullulanase was produced via solid-state fermentation using wheat bran as the substrate. Purification and characterization included specific activity, molecular weight, pH and temperature optima, and substrate specificity. The enzyme was immobilized in sodium alginate beads and used for clarifying mosambi, apple, and mango juices. Parameters such as yield, clarity, reducing sugar, total soluble solids (TSS), total phenol, and enzymatic browning were evaluated pre-and post-treatment. The purified pullulanase had a specific activity of 652.2 U/mg and a molecular weight of 135 kDa. Optimal pH values were 6.5 and 10, with maximum activity at 50 °C. Pullulanase showed a high affinity for pullulan and starch, indicating Pullulanase type II classification. Immobilized pullulanase improved yield, clarity, reducing sugar, TSS, and total phenol in fruit juices. The highest yield and clarity were observed in mosambi juice. Additionally, the enzyme reduced enzymatic browning, increasing the lightness of the juice. This study provides a significant contribution to the juice processing industry and represents the first report on the application of pullulanase for fruit juice processing.


Assuntos
Sucos de Frutas e Vegetais , Glicosídeo Hidrolases , Glicosídeo Hidrolases/química , Fenóis/análise , Açúcares/análise , Frutas/química
2.
Front Bioeng Biotechnol ; 11: 1139611, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37449089

RESUMO

Pullulanases are the most important industrial group of enzymes in family 13 glycosyl hydrolases. They hydrolyze either α-1,6 and α-1,4 or both glycosidic bonds in pullulan as well as other carbohydrates to produce glucose, maltose, and maltotriose syrups, which have important uses in food and other related sectors. However, very less reports are available on pullulanase production from native strains because of low yield issues. In line with the increasing demands for pullulanase, it has become important to search for novel pullulanase-producing microorganisms with high yields. Moreover, high production costs and low yield are major limitations in the industrial production of pullulanase enzymes. The production cost of pullulanase by using the solid-state fermentation (SSF) process can be minimized by selecting agro-industrial waste. This review summarizes the types, sources, production strategies, and potential applications of pullulanase in different food and other related industries. Researchers should focus on fungal strains producing pullulanase for better yield and low production costs by using agro-waste. It will prove a better enzyme in different food processing industries and will surely reduce the cost of products.

3.
Environ Monit Assess ; 195(7): 845, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-37318651

RESUMO

An effective micro-level air quality management plan requires high-resolution monitoring of pollutants. India has already developed a vast network of air quality monitoring stations, both manual and real time, located primarily in urban areas, including megacities. The air quality monitoring network consists of conventional manual stations and real time Continuous Ambient Air Quality Monitoring Stations (CAAQMS) which comprise state-of-the-art analysers and instruments. India is currently in the early stages of developing and adopting economical portable sensor (EPS) in air quality monitoring systems. Protocols need to be established for field calibration and testing. The present research work is an attempt to develop a performance-based assessment framework for the selection of EPS for air quality monitoring. The two-stage selection protocol includes a review of the factory calibration data and a comparison of EPS data with a reference monitor, i.e. a portable calibrated monitor and a CAAQMS. Methods deployed include calculation of central tendency, dispersion around a central value, calculation of statistical parameters for data comparison, and plotting pollution rose and diurnal profile (peak and non-peak pollution measurement). Four commercially available EPS were tested blind, out of which, data from EPS 2 (S2) and EPS 3 (S3) were closer to reference stations at both locations. The selection was made by evaluating monitoring results, physical features, measurement range, and frequency along with examining capital cost. This proposed approach can be used to increase the usability of EPS in the development of micro-level air quality management strategies, other than regulatory compliance. For regulatory compliance, additional research is needed, including field calibration and evaluating EPS performance through additional variables. This proposed framework may be used as starting point, for such experiments, in order to develop confidence in the use of EPS.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Ambientais , Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Poluição do Ar/análise , Calibragem , Material Particulado/análise , Literatura de Revisão como Assunto
4.
Int J Environ Sci Technol (Tehran) ; 19(2): 785-796, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34548875

RESUMO

Urban air pollution and exposure-related health impacts are being noticed and discussed very intensely in India. On the other hand, source-specific control is the primary focus for policymakers; however, diverse and complex sources make it difficult to immediately see the action and consequent impacts on better air quality. Many cities across the world have witnessed high air pollution levels at traffic junctions, more so in all Indian cities. Site-specific air pollution reduction can be a promising solution for managing the pollution level at highly polluted locations. CSIR-National Environmental Engineering Research Institute, India, has designed and developed Wind Augmentation and purifYing Unit (WAYU) to remove particulate and gaseous pollutants from urban hot spots such as traffic locations. In the present study, the authors attempted to evaluate the performance of two different designs of WAYU for the removal of particulate matters from polluted air at different traffic locations in Delhi City, the national capital territory of India. The performance analyses show that the current design of WAYU removes PM10 and PM2.5 concentrations in the range of 34-49% and 19-25%, respectively from the inlet air. The total PM collected from all WAYU devices was 34.19 kg from 120,557 operating hours' at all the sampling sites. The PM removal rate depends on the size-segregated particulate matter pollution load in the ambient air. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13762-021-03641-3.

5.
Sci Total Environ ; 798: 149143, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34375264

RESUMO

Critical assessment of spatio-temporal variations in pollution levels is a crucial step for identifying and prioritizing air pollution hotspots (APH) in urban areas. There is no universally accepted methodology for defining and delineating air pollution hotspot which can be source-specific, pollutant-specific and time-specific. The present research article is an attempt to develop a protocol for identifying APH for any pollutant within a city where-in three criteria-based innovative methodology has been derived. The three criteria are frequency of exceedance (% of days), scale of exceedance and consistency in exceedance (consecutive number of days) to the specified standards that need to be met continuously for at least three years. The suggested methodology has been applied on a three-year database (2018-2021) of 37 continuous ambient air quality stations to identify PM2.5 specific APH. The analysis indicates 11 APH in April, 9 in May, 2 in June and almost the entire city during the October-February months. Given prioritization of implementation of control actions, the identified APH during summer has been further physically examined to map source activity types and their suitability for ambient air quality monitoring stations as per the guidelines. The APH can be the priority areas for the implementation of control actions by urban local bodies. The management of air pollution at these priority areas would be more effective instead of city-scale management practice, which is difficult to implement and monitor.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Cidades , Monitoramento Ambiental , Material Particulado/análise , Estações do Ano
6.
J Genet Eng Biotechnol ; 19(1): 110, 2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34324093

RESUMO

BACKGROUND: Pullulanases are the significant industrial group in the 13 glycosyl hydrolases category, known as the α-amylases family. There are very few reports on pullulanase from fungal sources. Based on the above research gap, the present study was undertaken to explore the endophytic fungi for their pullulanase-producing capabilities. RESULTS: A total of 126 endophytes were isolated from Tradescantia pallida, Zea mays, and Trifolium alexandrinum. Aspergillus, Penicillium, and Ganoderma species recovered highest from the stem of Tradescantia palida. Fusarium was dominant in the stem and leaf of Zea mays. Penicillium, Aspergillus, Ganoderma, Cladosporium, Fusarium, and Alternaria were recovered from the Trifolium alexandrium. The Shannon index in Tradescantia pallida was highest in leaves while in Zea mays and Trifolium alexandrinum, it is highest in the stem. The Simpson's index is highest in the case of Zea mays stem and root. Species richness was indicated by Menhinick's index, and it was found that this value was highest in the roots of Trifolium alexandrinum. As per our knowledge, no comparative data is available on the endophytic diversity of the above plants taken for the study. Out of 126 endophytes, only 2.38% produced pullulanase while 7.94% produced amylase. The recovery of pullulanase-producing endophytic fungi was very less. But the importance of pullulanase is high as compared to amylase because it has both α-1,6 and α-1,4 hydrolyzing ability. Therefore, the most promising isolates were identified by ITS sequence analysis. Based on spore chain morphology, isolates BHU-25 and BHU-30 were identified as Penicillium sp. and Aspergillus species, respectively. This is the first report of pullulanase from endophytic Aspergillus and Penicillium. CONCLUSION: Endophytes Aspergillus sp. and Penicillium sp. produce pullulanase enzyme. This is the first report of pullulanase from endophytic Aspergillus and Penicillium.

7.
J Clin Orthop Trauma ; 10(5): 928-933, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31528070

RESUMO

INTRODUCTION: Open comminuted distal femur fractures are notorious for septic or aseptic non-union. The recommended fixed angle distal femur locking plate in such situations can lead to a septic non-union due to its extensive approach and further periosteal stripping. Supracondylar nails, though have a minimally invasive approach, are not suitable for type C2 and C3 (AO/ASIF) fractures. A monolateral fixator as damage control followed by plating may be recommended. But if wound healing is delayed it results in difficult articular reduction, poor alignment and a stiff knee. We therefore used ilizarov circular external fixators (ICEF) for such open fractures (type C1, C2 and C3) and analysed its radiological and functional outcomes. MATERIALS AND METHODS: 25 male patients, with a mean age of 31.04 ±â€¯6.62 years (range, 22-44 years), with open grade III type C distal femoral fractures were treated with ICEF. There were 7 fractures of type C1and C3 each, 11 were of type C2. Articular reduction and compression was achieved with inter-fragmentary screws through minimal open technique by extending the open wound and then stabilising the fracture with ICEF. The main outcomes evaluated were union, range of motion, final shortening, Knee Society scoring and ASAMI scoring system for radiological and functional outcomes. RESULTS: The mean follow-up period was 19.12 ±â€¯1.14 months. All fractures except two united at a mean period of 30 ±â€¯3.02 weeks, without the need of bone grafts. The bony assessment (according to ASAMI score) was excellent in 8 cases (33.33%), good in 9 cases (37.5%) and fair in 5 cases (20.83%), while there were 2 poor clinical end results. The functional results were excellent in 6 cases (25%), good in 9 cases (37.5%) fair in 6 cases (25%) poor in 3 cases (12.5%). The complications included shortening, extension lag and pin tract infections. CONCLUSION: With the encouraging results, the use of ICEF with minimal internal fixation in grade III open comminuted distal femur fractures as a primary definitive treatment is a valuable alternative.

8.
J Food Sci ; 83(12): 3076-3084, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30440092

RESUMO

Foxtail millet porridge was prepared using germinated grains and milk and was evaluated for its storage stability after thermal processing at ultra-high temperatures (UHT) of 142 °C for 5 s and retort processing temperatures of 121.5 °C for 15 min. Various physical, chemical, and microbial changes of the porridge were studied for a storage period of 180 days at 25 ± 1 °C. Using consumer perception and survival analysis, the predicted shelf life of the UHT treated and retort processed foxtail millet porridge samples stored at 25 ± 1 °C was found to be 186 ± 9 days and 245 ± 15 days, respectively. Also, data from consumer liking, profiling, physical, chemical, and microbial parameters showed significant changes (P < 0.05) in the thermally treated packaged porridge samples over time. As the consumer overall acceptability decreased, the detection of positive attributes (thick and uniformly colored texture and appearance; grainy mouth texture; caramel taste and aroma) in the porridge decreased, while the detection of negative attributes (uneven, decolored, and curdled texture and appearance; sticky mouth texture; cooked, sour and off smell; cooked, sour and off taste) increased. The present study could establish a significant difference (P < 0.05) in the storage induced properties of UHT and retort processed porridge samples. The analytical evaluation of foxtail millet porridge found that UHT treated porridge was better in quality, but consumers preferred retort processed porridge. PRACTICAL APPLICATION: The quality and sensory attributes, evaluated for UHT treated and retort processed porridge samples during the storage period of 180 days, were found to be contradictory. Based on the results of CATA sensory analysis, the shelf life of UHT treated and retort processed porridge samples was predicted to be more than 6 months. Therefore, both UHT treatment and retort processing can be effectively applied to prepare a ready to eat milk based porridge using germinated foxtail millet grains.


Assuntos
Armazenamento de Alimentos , Germinação , Temperatura Alta , Setaria (Planta)/química , Adulto , Clostridium botulinum/isolamento & purificação , Comportamento do Consumidor , Feminino , Contaminação de Alimentos , Microbiologia de Alimentos , Embalagem de Alimentos , Humanos , Concentração de Íons de Hidrogênio , Metabolismo dos Lipídeos , Reação de Maillard , Masculino , Pessoa de Meia-Idade , Salmonella/isolamento & purificação , Setaria (Planta)/microbiologia , Staphylococcus aureus/isolamento & purificação , Paladar , Viscosidade
9.
Nat Commun ; 8(1): 906, 2017 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-29030556

RESUMO

There are both fundamental and practical motivations for studying whether quantum entanglement can exist in macroscopic systems. However, multiparty entanglement is generally fragile and difficult to quantify. Dicke states are multiparty entangled states where a single excitation is delocalized over many systems. Building on previous work on quantum memories for photons, we create a Dicke state in a solid by storing a single photon in a crystal that contains many large atomic ensembles with distinct resonance frequencies. The photon is re-emitted at a well-defined time due to an interference effect analogous to multi-slit diffraction. We derive a lower bound for the number of entangled ensembles based on the contrast of the interference and the single-photon character of the input, and we experimentally demonstrate entanglement between over two hundred ensembles, each containing a billion atoms. We also illustrate the fact that each individual ensemble contains further entanglement.Multipartite entanglement is of both fundamental and practical interest, but is notoriously difficult to witness and characterise. Here, Zarkeshian et al. demonstrate multipartite entanglement in an atomic frequency comb storing a single photon in a Dicke state spread over a macroscopic ensemble.

10.
J Food Sci Technol ; 51(11): 2907-16, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26396286

RESUMO

Rice milling industry is one of the most energy consuming industries. Like capital, labour and material, energy is one of the production factors which used to produce final product. In economical term, energy is demand-derived goods and can be regarded as intermediate good whose demand depends on the demand of final product. This paper deals with various types of energy pattern used in rice milling industries viz., thermal energy, mechanical energy, electrical energy and human energy. The important utilities in a rice mill are water, air, steam, electricity and labour. In a rice mill some of the operations are done manually namely, cleaning, sun drying, feeding paddy to the bucket elevators, weighing and packaging, etc. So the man-hours are also included in energy accounting. Water is used for soaking and steam generation. Electricity is the main energy source for these rice mills and is imported form the state electricity board grids. Electricity is used to run motors, pumps, blowers, conveyors, fans, lights, etc. The variations in the consumption rate of energy through the use of utilities during processing must also accounted for final cost of the finished product. The paddy milling consumes significant quantity of fuels and electricity. The major energy consuming equipments in the rice milling units are; boilers and steam distribution, blowers, pumps, conveyers, elevators, motors, transmission systems, weighing, etc. Though, wide variety of technologies has been evolved for efficient use of energy for various equipments of rice mills, so far, only a few have improved their energy efficiency levels. Most of the rice mills use old and locally available technologies and are also completely dependent on locally available technical personnel.

12.
Int J Food Sci Nutr ; 61(1): 1-10, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19961353

RESUMO

Studies revealed that Stevia has been used throughout the world since ancient times for various purposes; for example, as a sweetener and a medicine. We conducted a systematic literature review to summarize and quantify the past and current evidence for Stevia. We searched relevant papers up to 2007 in various databases. As we know that the leaves of Stevia plants have functional and sensory properties superior to those of many other high-potency sweeteners, Stevia is likely to become a major source of high-potency sweetener for the growing natural food market in the future. Although Stevia can be helpful to anyone, there are certain groups who are more likely to benefit from its remarkable sweetening potential. These include diabetic patients, those interested in decreasing caloric intake, and children. Stevia is a small perennial shrub that has been used for centuries as a bio-sweetener and for other medicinal uses such as to lower blood sugar. Its white crystalline compound (stevioside) is the natural herbal sweetener with no calories and is over 100-300 times sweeter than table sugar.


Assuntos
Extratos Vegetais , Stevia/química , Edulcorantes , Animais , Humanos , Fitoterapia , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Folhas de Planta , Ratos , Edulcorantes/farmacologia , Edulcorantes/uso terapêutico
13.
Environ Monit Assess ; 148(1-4): 397-408, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18247148

RESUMO

In the present study, the impact of the flyover construction to curb traffic congestion problem has been assessed in terms of traffic decongestion, time saving, fuel saving and emission reduction. A flyover has also been constructed over four signalized junctions in the main commercial area in Nagpur city, India. It was found that about 35% of the total traffic is diverted to the flyover, which results in a reduction of about 32% in the total emission generation. Travel on the flyover resulted in as much as 60-70% saving in time, compared to the travel on the main road, particularly when all the four signals are found to be in the red phase. The loss of fuel for combustion and the associated cost resulting from waiting for the signal to change are also estimated, and these are found to be significant.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Cidades , Planejamento de Cidades , Meio Ambiente , Meios de Transporte , Emissões de Veículos/análise , Poluentes Atmosféricos/análise , Gasolina , Humanos , Índia , Veículos Automotores
14.
Sci Total Environ ; 376(1-3): 27-39, 2007 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-17316766

RESUMO

The assimilation potential (assimilative capacity) of the atmosphere can be represented in two ways: one as the ventilation coefficient and the other as the dispersion potential of emission loads discharged into the region. In the present study, the atmospheric assimilation potential of a typical urban area in Kochi city has been determined with respect to sulfur dioxide (SO(2)). The ventilation coefficient is directly proportional to the assimilation potential of the atmosphere and has been computed using meteorological parameters in all four seasons (winter, summer, monsoon and post-monsoon) of the years 1998-1999 represented by January, April, July and October respectively. The diurnal variation in ventilation coefficients shows that the assimilative capacity of the atmosphere is high during the afternoon and is reduced during the evening and morning in all the seasons. Among all the seasons, monsoon and post-monsoon have the poorest assimilative capacity throughout the day. In the second approach, the assimilation potential is estimated through dispersion modelling in terms of the concentration of pollutants, which is inversely proportional to the assimilative capacity of the atmosphere. The Industrial Source Complex (ISC) dispersion model for point sources has been used to predict the spatial and temporal distribution of SO(2) under three different industrial scenarios (type of industries existing in the Kochi region, refinery and power plant). The model predictions indicate that monsoon is the most critical season having maximum pollution, followed by summer and post-monsoon. Lowest pollution was observed in winter. The assimilative capacity in terms of the ventilation coefficient is very poor indicating high pollution potential in all the seasons. However, dispersion modeling suggests that if industrial development is planned properly, additional industrial sources can be accommodated by restricting the emission loads to be within the assimilation potential of the region.


Assuntos
Poluentes Atmosféricos/análise , Modelos Teóricos , Dióxido de Enxofre/análise , Atmosfera , Indústria Química , Cidades , Índia , Resíduos Industriais , Temperatura , Vento
15.
J Environ Manage ; 84(4): 473-83, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16949195

RESUMO

Air pollution has become a matter of grave concern, particularly in mega-cities and urban areas, where the situation is alarming and becoming more and more severe day-by-day and warrants, therefore, careful planning to facilitate future industrial development. Site selection, with the objective of minimizing adverse environmental impacts based on environmental criteria is a vital prerequisite, particularly for air polluting industries. In order to locate any air polluting industry, the assimilative capacity of the region needs to be assessed carefully and planned accordingly, so that the receiving environment is not adversely affected. Assimilative capacity of a region/airshed, widely represented through the ventilation coefficient by many researchers in the past, does not give a clear picture about the amount of emission load that can be assimilated in a given region. The ventilation coefficient, at best, can only present a broad picture about the air pollution dispersion potential (low, medium or high) of the region. A modified approach, which utilizes air quality modelling as a tool to estimate the maximum allowable emission load that a region can assimilate without violating the stipulated standards, has been used for estimating the assimilative capacity of the air environment. Details of this approach have been presented in this paper through a case study carried out for the Kochi region, located in the Kerala State of India. A variety of emission and meteorological scenarios have been considered and critical emission loads have been estimated. This approach shall provide necessary technical guidance to the environmental regulatory authorities as well as to the industries in planning environment friendly industrial development.


Assuntos
Poluição do Ar/prevenção & controle , Modelos Teóricos , Poluentes Atmosféricos/análise , Meio Ambiente , Índia , Resíduos Industriais/prevenção & controle , Indústrias , Material Particulado/análise , Estações do Ano , Dióxido de Enxofre/análise , Temperatura , Vento
16.
Environ Monit Assess ; 120(1-3): 461-76, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16741797

RESUMO

For measurement of sulfur dioxide (SO2) in ambient air, the United States Environment Protection Agency (US EPA) had recommended the PRA dye-based colorimetric method as a reference technique. The method has been developed and applied in many countries for a longtime; however information regarding the sensitivity of the method with respect to sampling and analysis conditions is not available. Collaborative studies conducted in some of the South East Asian countries indicated substantial variations (of the order of 50%) in the measured concentrations against the true values. It was observed that dye used for color development plays an important role and even a slight variation in the way the dye solution is prepared can cause substantial variation in the measured SO2 concentration. Because a major objective of air quality measurements is to relate air pollution concentration to the effects of air pollution, it is important that the method used should yield accurate levels of the pollutant, so that appropriate management plans can be devised and implemented effectively. In the present investigation, therefore, the role of dye used in SO2 monitoring method has been highlighted. Different makes of dyes prepared in different modes were used to study the variation in the measured SO2 concentration levels. Specifications of all the dyes were also tested. Need for use of certified reference material (CRM) for SO2 has also been emphasized.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar , Monitoramento Ambiental/métodos , Dióxido de Enxofre/análise , Ar , Índia , Indicadores e Reagentes
17.
Environ Monit Assess ; 119(1-3): 557-69, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16741810

RESUMO

Air pollution has become a growing problem in megacities and large urban areas through out the globe, and transportation is recognized as the major source of air pollution in many cities, especially in developing countries. Contribution of automobiles is reported in the range of 40 to 80% of the total air pollution. The challenge facing megacities is how to reduce the adverse environmental impacts and other negative effects of transportation without giving up the benefits of mobility. The dilemma becomes most pressing under conditions of rapid urban growth, which is likely to increase travel demand significantly. The paper is aimed at understanding the problem of vehicular pollution vis-a-vis ambient air quality for a highly traffic affected megacity, Delhi, wherein, the contribution of transport sector was estimated to be as high as 72%. An effort has been made to review and evaluate the benefits (in terms of improved air quality) of the technological interventions/policies adopted for vehicular pollution control in Delhi. It also highlights the outcome of the efforts and suggests further improvements thereon. The importance of public participation and awareness are also discussed. The paper focuses on deriving the benefits of the implementation of management strategies, supported by scientific and technical data/interpretation, so that the people can realize and participate in the government's endeavor for clean city drive in a more effective manner.


Assuntos
Poluição do Ar/análise , Ar/análise , Emissões de Veículos/análise , Ar/normas , Poluentes Atmosféricos/análise , Poluição do Ar/prevenção & controle , Cidades , Monitoramento Ambiental/métodos , Índia , Emissões de Veículos/prevenção & controle
18.
Environ Monit Assess ; 105(1-3): 1-9, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15952508

RESUMO

A study was carried out with specific reference to NO2 measurements in three countries (designated as A, B and C), which use three different manual methods; viz. Sodium Arsenite, Greiss Saltzman and TGS-ANSA for the determination of NO2 in ambient air. Significant deviation (up to 36 + %) was observed in measured NO, ion concentration when spiked samples were analyzed using these methods. Further, to make the data inter-comparable, exhaustive laboratory studies were carried out on these manual methods. Different concentration levels of NO2 were generated in the laboratory and analyzed by these methods simultaneously. The results were evaluated statistically. An interrelationship among the methods was established as method conversion factors (MCF). This would be useful in relating atmospheric concentration of NO2 among various countries, where different measurement techniques are adopted.


Assuntos
Poluentes Atmosféricos/análise , Técnicas de Química Analítica/métodos , Monitoramento Ambiental/métodos , Dióxido de Nitrogênio/análise , Arsenitos , Reprodutibilidade dos Testes , Compostos de Sódio
19.
Environ Monit Assess ; 89(3): 305-14, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14632096

RESUMO

Sodium arsenite (modified Jacobs and Hochheiser method; hereafter referred as SA), the most widely used manual monitoring method for determination of nitrogen dioxide (NO2) in ambient air, particularly in developing countries has been evaluated and compared with US EPA recommended equivalent method of TGS-ANSA (hereafter referred as ANSA). NO2 concentrations generated from laboratory test atmosphere were analyzed by these two methods and were compared statistically. Laboratory evaluations showed that SA method has high sensitivity to different sampling conditions, which normally vary during actual field monitoring. Hence, correction factors for absorption efficiency were estimated for SA and ANSA methods. Absorption efficiency of NO2 in SA method was found to be much lower (64%) as against the reported value of 82% at the method recommended sampling conditions, whereas for ANSA method, it was found 1.0 as against the reported value of 0.93. After applying derived correction factors, both the methods produced almost similar concentration values of NO2.


Assuntos
Poluentes Atmosféricos/análise , Países em Desenvolvimento , Monitoramento Ambiental/métodos , Dióxido de Nitrogênio/análise , Oxidantes Fotoquímicos/análise , Absorção , Arsenitos/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Compostos de Sódio/química
20.
J Environ Monit ; 4(4): 579-82, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12196004

RESUMO

The effect of the two most critical parameters, the sample flow rate and sampling duration, on the absorption efficiency of NO2 in the sodium arsenite method of nitrogen dioxide determination in ambient air was studied. Laboratory experiments showed a high sensitivity to these parameters, which were subjected to variation during actual field monitoring. The reported NO2 absorption efficiency of the method of 82% at a flow rate of 0.2 l min-1 was found to be as low as 33% at a flow rate of 1.0 l min-1 for a sampling duration of 24 h. Similarly, a considerable decrease in absorption efficiency with increasing sampling duration from 2 to 24 h was observed at a particular flow rate. Correction factors for the absorption efficiency were evolved that can be used to update the existing database, as well as future NO2 data generated using this manual monitoring method.


Assuntos
Dióxido de Nitrogênio/análise , Oxidantes Fotoquímicos/análise , Absorção , Arsenitos/química , Monitoramento Ambiental/métodos , Inibidores Enzimáticos/química , Reprodutibilidade dos Testes , Compostos de Sódio/química , Manejo de Espécimes , Reagentes de Sulfidrila/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...