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321.
Maumita Saha Subhasis Sarkar Biplab Sarkar Bipin Kumar Sharma Surajit Bhattacharjee Prosun Tribedi 《Environmental science and pollution research international》2016,23(5):3984-3999
Siderophores are small organic molecules produced by microorganisms under iron-limiting conditions which enhance the uptake of iron to the microorganisms. In environment, the ferric form of iron is insoluble and inaccessible at physiological pH (7.35–7.40). Under this condition, microorganisms synthesize siderophores which have high affinity for ferric iron. These ferric iron-siderophore complexes are then transported to cytosol. In cytosol, the ferric iron gets reduced into ferrous iron and becomes accessible to microorganism. In recent times, siderophores have drawn much attention due to its potential roles in different fields. Siderophores have application in microbial ecology to enhance the growth of several unculturable microorganisms and can alter the microbial communities. In the field of agriculture, different types of siderophores promote the growth of several plant species and increase their yield by enhancing the Fe uptake to plants. Siderophores acts as a potential biocontrol agent against harmful phyto-pathogens and holds the ability to substitute hazardous pesticides. Heavy-metal-contaminated samples can be detoxified by applying siderophores, which explicate its role in bioremediation. Siderophores can detect the iron content in different environments, exhibiting its role as a biosensor. In the medical field, siderophore uses the “Trojan horse strategy” to form complexes with antibiotics and helps in the selective delivery of antibiotics to the antibiotic-resistant bacteria. Certain iron overload diseases for example sickle cell anemia can be treated with the help of siderophores. Other medical applications of siderophores include antimalarial activity, removal of transuranic elements from the body, and anticancer activity. The aim of this review is to discuss the important roles and applications of siderophores in different sectors including ecology, agriculture, bioremediation, biosensor, and medicine. 相似文献
322.
Introduction
The kinetics of the transformation of ammonia and acid gases into components of PM2.5 has been examined. The interactions of existing aerosols and meteorology with the transformation mechanism have also been investigated. The specific objective was to discern the kinetics for the gas-to-particle conversion processes where the reactions of NH3 with H2SO4, HNO3, and HCl take place to form (NH4)2SO4, NH4NO3, and NH4Cl, respectively, in PM2.5. 相似文献323.
324.
In this study, seven soil and sedimentary humic acid samples were analyzed by synchronous scan fluorescence (SSF) spectroscopy. The spectra of these humic acids were compared to each other and characterized, based on three major SSF peaks centered at approximately 281, 367 and 470 nm. Intensity ratios were calculated based on these peaks that were used to numerically assist in source discrimination. All humic acid samples were then reacted with Ferrate(VI) and were again analyzed with SSF. Upon the addition of Ferrate(VI) SSF spectra were obtained which more readily differentiated humic acid source. This method will assist geochemists and water management districts in tracing sources of organic matter to receiving water bodies and may aid in the elucidation of the chemical nature of humic acids. 相似文献
325.
Ionic composition of wet precipitation over the southern slope of central Himalayas,Nepal 总被引:1,自引:0,他引:1
Lekhendra Tripathee Shichang Kang Jie Huang Mika Sillanpää Chhatra Mani Sharma Zoe Lucia Lüthi Junming Guo Rukumesh Paudyal 《Environmental science and pollution research international》2014,21(4):2677-2687
Severe atmospheric pollution transported to Himalayas from South Asia may affect fragile ecosystem and can be harmful for human health in the region. In order to understand the atmospheric chemistry in the southern slope of central Himalayas, where the data is limited, precipitation has been sampled at four sites: Kathmandu (1,314 m), Dhunche (2,065 m), Dimsa (3,078 m), and Gosainkunda (4,417 m) in Nepal for over a 1-year period characterized by an urban, rural, and remote sites, respectively. HCO3 ? is the dominant anion, while the NH4 + is the dominant cation in precipitation at the four sites. Generally, most of ions (e.g., SO4 2?, NO3 ?, NH4 +, HCO3 ?, and Ca2+) have higher concentrations in urban site compared to the rural sites. Neutralization factor calculation showed that precipitation in the region is highly neutralized by NH4 + and Ca2+. Empirical orthogonal function and correlation analysis indicated that the precipitation chemistry was mostly influenced by crustal, anthropogenic, and marine sources in Nepal. Among different sites, urban area was mostly influenced by anthropogenic inputs and crustal dusts, whereas remote sites were mostly from marine and crustal sources. Seasonal variations show higher ionic concentrations during non-monsoon seasons mainly due to limited precipitation amount. On the other hand, lower ionic concentrations were observed during monsoon season when higher amount of precipitation washes out aerosols. Thus, precipitation chemistry from this work can provide a useful database to evaluate atmospheric environment and its impacts on ecosystem in the southern slope of central Himalayas, Nepal. 相似文献
326.
Virender K. Sharma Mehmet Oturan Hyunook Kim 《Environmental science and pollution research international》2014,21(14):8525-8533
Sucralose, a chlorinated carbohydrate, has shown its increased use as an artificial sweetener and persistently exists in wastewater treatment plant effluents and aquatic environment. This paper aims to review possible degradation of sucralose and related carbohydrates by biological, electrochemical, chemical, and advanced oxidation processes. Biodegradation of sucralose in waterworks did not occur significantly. Electrochemical oxidation of carbohydrates may be applied to seek degradation of sucralose. The kinetics of the oxidation of sucralose and the related carbohydrates by different oxidative species is compared. Free chlorine, ozone, and ferrate did not show any potential to degrade sucralose in water. Advanced oxidation processes, generating highly strong oxidizing agent hydroxyl radicals (?OH), have demonstrated effectiveness in transforming sucralose in water. The mechanism of oxidation of sucralose by ?OH is briefly discussed. 相似文献
327.
Sharma KK Dubey JK Deka SC Chandrasekaran S Kalpana Gupta P Kumar A Vandana Devi MJ Singh B Baruah AA Kennedy JS Sharma ID Patyal SK Nath A 《Chemosphere》2007,68(4):790-796
Spiromesifen (Oberon) is a new insecticide and miticide of chemical class ketoenol active against white flies (Bemisia spp., Trialeuroides spp.) and spider mites (Tetranychus and Panonychus spp.). Due to its potential significance in insect resistance management, it is important to establish its behaviour on crop and environment. In the present study, the degradation/dissipation of spiromesifen on tea crop under tropical environmental conditions was studied and its DT(50) (t(1/2)), and DT(90) (time to reduce to 90% of the initial value) were estimated. Spiromesifen was sprayed on tea crop after first rain flush at four different locations @ 96 and 192ga.i.ha(-1). Samples of tea leaves were drawn at 0, 1, 3, 5, 7, 10, 15, 21 and 30 days after treatment and that of soil at 10 days after treatment and at harvest from 0 to 15 and 15 to 30cm layers. After crude extraction of tea leaves for spiromesifen residues with acetone:water, the contents were partitioned with cyclohexane:ethyl acetate and cleaned up on Florosil column. Soil residues were also extracted similarly. Quantification of residues was done on GC-MS in Selected Ion Monitoring (SIM) mode in mass range 271-274m/z. The LOQ of this method was found to be 0.05microgg(-1) while LOD being 0.015microgg(-1). The DT(50) of spiromesifen when applied at recommended doses in tea leaves was found to be 5.0-8.5 days. Ninety-nine percent degradation was found to occur within 33-57 days after application. In soil, no residues of spiromesifen were detectable 10 days after treatment. 相似文献
328.
Application of riverbed sand for the adsorptive separation of cadmium(II) from aqueous solutions has been investigated. Removal increased from 26.8 to 56.4% by decreasing the initial concentration of cadmium from 7.5 x 10(-5) to 1.0 x 10(-5)M at pH 6.5, 25 degrees C temperature, agitation speed of 100 rpm, 100 microm particle size and 1.0 x 10(-2) NaClO4 ionic strength. Process of separation is governed by first order rate kinetics. The value of rate constant of adsorption, k(ad), was found to be 2.30 x 10(-2)per min at 25 degrees C. Values of coefficient of mass transfer, beta L, were calculated and its value at 25 degrees C was found to be 1.92 x 10(-2)cm/s. Values of Langmuir constant were calculated. Values of thermodynamic parameters delta G0, delta H0 and delta S0 were also calculated and were recorded as -0.81 kcal/mol, -9.31 kcal/mol and -28.10 cal/mol at 25 degrees C. pH has been found to affect the removal of cadmium significantly and maximum removal, 58.4%, has been found at pH 8.5. Process can be used for treatment of cadmium(II) rich wastewaters. 相似文献
329.
Sharma KK Rao CS Dubey JK Patyal SK Parihar NS Battu RS Sharma V Gupta P Kumar A Kalpana Jaya M Singh B Sharma ID Nath A Gour TB 《Environmental monitoring and assessment》2007,132(1-3):25-31
In a field study carried out at three different locations, the dissipation of spiromesifen on cotton and chili was studied
and its DT50, and DT99 were estimated at each location. Spiromesifen was sprayed on chili at 96 and 192 g a.i. ha−1 and cotton at 120 and 240 g a.i. ha−1. Samples of chili fruits were drawn at 0, 1, 3, 5, 7, 10, 15, 21, 30 days after treatment and that of cotton seed and lint
at first picking and harvest. Soil samples were drawn 30 days after treatment from 0 to 15 and 15 to 30 cm layer. Quantification
of residues was done on GC–MS in Selected Ion Monitoring (SIM) mode in mass range 271–274 m/z. The LOQ of this method was
found 0.033 μg g−1, LOD being 0.01 μg g−1. The DT50 of spiromesifen when applied at recommended doses in chili fruits was found to be 2.18–2.40 days. Ninety-nine percent degradation
was found to occur within 14.5–16.3 days after application. Residues of spiromesifen were not detected in cotton seed and
lint samples at the first picking. In soil, no residues of spiromesifen were detectable 15 days after treatment. 相似文献
330.
There is a paradigm shift from non renewal resources to renewable resources in view of problems of disposal of plastic products
after their life cycle. This paper deals with the approach, preparation and product properties of polymer prepared by using
polysaccharide based biodegradable polymer. Basic material has been prepared by mixing LDPE, LDPE-g-mA (LDPE grafted with
(0.5%) maleic anhydride (1:1)) containing a polar group in the LDPE backbone. Prepared basic material has been compounded
in twin screw extruder with 0, 2.5, 5.0, 7.5, 10.0, 12.5 & 15% of Potato Starch. Thereafter, after conditioning blown film
samples were prepared using extrusion film blowing technique, under temperature profile ranging from 120 to 160 °C. Packaging
films have been prepared with maximum 15% potato starch contents and have been characterized by FTIR, DSC, TGA, and XRD techniques
to ascertain its impact on some structural and thermal properties like thermal stability, flexibility, crystallinity, crystal
size etc. 相似文献