Quantification of Organochlorine Pesticide Residues in the Buffalo Milk Samples of Delhi City, India

The ill effects of green revolution include residues of extensively used chemical pesticides in various environmental components. The present study was designed to analyze the levels of organochlorine pesticide residues along with chemical composition in buffalo milk samples collected from different localities of Delhi. Milk monitoring can yield information about the kinds and quantities of pesticides in the environment as well as in our daily diet. In this study, the residue of three different organochlorine pesticides, namely Hexachlorocyclohexane (HCH), Dichlorodiphenyltrichloroethane (DDT) and Endosulfan have been reported. Residues of Lindane exceeded the Maximum Residual Limit values in 50% of the samples is a cause of serious concern. The p,p’-DDT was detected in 70% of the samples with p,p’-DDE (dichlorodiphenyldichloroethylene) in 80% of the milk samples of different parts of Delhi state. DDD (Dichlorodiphenyldichloroethane) another metabolite of p,p’-DDT was detected in 65% of the milk samples. The analysis indicates that DDT is the major contaminants in different parts of Delhi state. α and β endosulfan were detected in 35% and 40% of the samples analyzed. The statistical correlation shows no significant correlation between chemical compositions of the samples. The presence of multiple chemicals in virtually all samples of buffalo milk raises new questions about the possible toxicological impacts of chemical mixtures on an infant’s developing nervous and immune systems and reproductive organs.

Homogeneous boron doping in a TiO_2 shell supported on a TiB_2 core for enhanced photocatalytic water oxidation

Photocatalytic water oxidation for O2evolution is known as a bottle neck in water splitting.Various strategies have been conducted to keep the energetics of photogenerated holes or to create more holes in the bulk to reach the surface for efficient photocatalytic water oxidation.Our previous study demonstrated the effectiveness of interstitial boron doping in improving photocatalytic water oxidation by lowering the valence band maximum of TiO2with a concentration gradient of boron.In this study,homogeneous doping of interstitial boron was realized in a TiO2shell with mixed anatase/rutile phases that was produced by the gaseous hydrolysis of the surface layer of TiB2crystals in a moist argon atmosphere.Consequently,the homogeneous doping and lowered valence band maximum improved the energetics of holes for efficient photocatalytic water oxidation.

Chemical Composition, Characterization and Factors Affecting Household Dust (<20 µm) in Greater Cairo, Egypt

Adverse health and environmental effects of household dust are derived from their chemical composition and properties. In this study, household, stairs and entryway dust (<20 μm) samples from homes located in urban, residential and residential near to industrial area in Greater Cairo during summer 2013 were collected to study their chemical composition, characterization and factors affecting them. Results indicate that the levels of measured anions and cations were higher in the household compared to stairs and entryway dust. The highest concentration of ?, , Cl-?,?, Na+, K+, Ca2+ and Mg2+ in the household and entryway dust was found in urban area. was abundant in household, entryway and stairs dust followed by Cl- and . Its average concentrations were 21.38, 14.57 and 15.83 mg/g, respectively. The household/entryway (I/O) concentration ratios of measured ion components indicate that these species might derive from indoor sources, although outdoor sources could be present as well. pH values of household, stairs and entryway dust ranged from 6.43 to 8.53, indicating that these dusts brought a large amount of crustal species, and might alleviate the tendency of acidification. The relationships between the concentrations of acidic components ( and ) and basic components (, Ca2+ and Mg2+) in household, stairs and entryway dust confirm that the acidity of dust is neutralized. Ca2+ and in household and stairs dust and Ca2+ and Mg2+ in entryway dust are the most dominant neutralization substances.

Acid leaching of heavy metals from contaminated soil collected from Jeddah,Saudi Arabia:kinetic and thermodynamics studies

Urban soils polluted with heavy metals are of increasing concern because it is greatly affecting human health and the ecological systems.Hence,it is mandatory to understand the reasons behind this pollution and remediate the contaminated solid.The removal of heavy metals from contaminated soil samples collected from the vicinity of the sewage lake in Jeddah,Saudi Arabia,was explored.The leaching process was studied kinetically and thermodynamically for better understanding of the remediation process.The results showed that the soil samples were slightly basic in nature,and tend to be more neutral away from the main contaminated sewage lake area.The total metal content in the soil samples was measured using the aqua regia extractions by ICPOES and the results showed that many of the heavy metals present have significant concentrations above the tolerable limits.In general,the metal concentrations at different sites indicated that the heavy metal pollution is mainly due to the sewage discharge to the lake.The results showed excellent correlation between the concentrations of Co,As,and Hg with the distance from the main contaminated area.The leaching of Co,As,and Hg using 1.0 M hydrochloric acid from the soil was studied kinetically at different temperatures and the experimental results were fitted using different kinetics models.The experimental data were best described with two-constant rate and Elovich equation kinetic models.Also,the thermodynamic study showed that the leaching process was spontaneous,endothermic and accompanied with increase in the entropy.In general,the polluted soil could be remediated successfully from the heavy metals using the acid leaching procedure in a short period of time.

Boosting efficiency and stability of perovskite solar cells with nickel phthalocyanine as a low-cost hole transporting layer material

The efficiency of perovskite solar cells（PSCs） has increased from around 4% to over 22% following a few years of intensive investigation. For most PSCs, organic materials such as 2,2＇,7,7＇-tetrakis（N,Npdimethoxyphenylamino）-9,9＇-spirobifluorene（spiro-OMeTAD） are used as the hole transporting materials（HTMs）, which are thermally and chemically unstable and also expensive. Here, we explored nickel phthalocyanine（NiPc） as a stable and cost-effective HTM to replace the conventionally used spiroOMeTAD. Because of its high carrier mobility and proper band alignments, we achieved a PCE of 12.1% on NiPc based planar device with short-circuit current density（Jsc） of 17.64 mAcm（-2）, open circuit voltage（Voc） of 0.94 V, and fill factor（FF） of 73%, outperforming the planar device based on copper phthalocyanine（CuPc） that is an outstanding representative of metal phthalocyanines（MPcs） reported. Moreover,the device with NiPc shows much improved stability compared to that based on the conventional spiroOMeTAD as a result of NiPc＇s high stability. Photoluminescence（PL） and Impedance spectroscopy analysis results show that thermally deposited NiPc has good hole-extraction ability. Our results suggest that NiPc is a promising HTM for the large area, low cost and stable PSCs.

Maximizing the visible light photoelectrochemical activity of B/N-doped anatase TiO_2 microspheres with exposed dominant {001} facets

Anatase TiO2 microspheres with exposed dominant {001} facets were doped with interstitial boron to have a concentration gradient with the maximum concentration at the surface. They were then further doped with substitutional nitrogen by heating in an ammonia atmosphere at different temperatures from 440 to 560℃ to give surface N concentrations ranging from 7.03 to 15.47 at%. The optical absorption, atomic and electronic structures and visible-light photoelectrochemical water oxidation activity of these materials were investigated. The maximum activity of the doped TiO2 was achieved at a nitrogen doping temperature of 520℃ that gave a high absorbance over the whole visible light region but with no defect-related background absorption.

Ni/TiO_2-SiO_2上光催化重整葡萄糖以低CO选择性制H_2(英文)

Nano-sized Ni particles on TiO2-SiO2 were synthesized by the two methods of photo-assisted deposition(PAD) and impregnation.H2,which is a promising energy carrier,with a low CO concentration was produced by the photocatalytic reforming of glucose(a model biomass) on the Ni/TiO2-SiO2 catalyst.The supported Ni enhanced the rate of H2 production while it suppressed CO selectivity.The catalysts were characterized by X-ray diffraction,X-ray absorption fine structure,transmission electron microscope,and nitrogen adsorption analysis.Both H2 production and CO selectivity were strongly dependent on the preparation method,and PAD-Ni/TiO2-SiO2 was the better catalyst for H2 production with the lowest CO concentration.

Modeling the impacts of temperature and precipitation changes on soil CO_2 fluxes from a Switchgrass stand recently converted from cropland

Switchgrass（Panicum virgatum L.） is a perennial C_4 grass native to North America and successfully adapted to diverse environmental conditions. It offers the potential to reduce soil surface carbon dioxide（CO_2） fluxes and mitigate climate change. However, information on how these CO_2 fluxes respond to changing climate is still lacking. In this study, CO_2 fluxes were monitored continuously from 2011 through 2014 using high frequency measurements from Switchgrass land seeded in 2008 on an experimental site that has been previously used for soybean（Glycine max L.） in South Dakota, USA. DAYCENT, a process-based model, was used to simulate CO_2 fluxes. An improved methodology CPTE[Combining Parameter estimation（PEST） with ＂Trial and Error＂ method] was used to calibrate DAYCENT. The calibrated DAYCENT model was used for simulating future CO_2 emissions based on different climate change scenarios. This study showed that：（i） the measured soil CO_2 fluxes from Switchgrass land were higher for 2012 which was a drought year, and these fluxes when simulated using DAYCENT for long-term（2015–2070） provided a pattern of polynomial curve;（ii） the simulated CO_2 fluxes provided different patterns with temperature and precipitation changes in a long-term,（iii） the future CO_2 fluxes from Switchgrass land under different changing climate scenarios were not significantly different, therefore, it can be concluded that Switchgrass grown for longer durations could reduce changes in CO_2 fluxes from soil as a result of temperature and precipitation changes to some extent.

燃烧源氨排放对灰霾期间北京大气铵的重要贡献

Aerosol ammonium(NH_(4)^(+)),mainly produced from the reactions of ammonia(NH_(3))with acids in the atmosphere,has significant impacts on air pollution,radiative forcing,and human health.Understanding the source and formation mechanism of NH_(4)^(+)can provide scientific insights into air quality improvements.However,the sources of NH_(3)in urban areas are not well understood,and few studies focus on NH_(3)/NH_(4)^(+)at different heights within the atmospheric boundary layer,which hinders a comprehensive understanding of aerosol NH_(4)^(+).In this study,we perform both field observation and modeling studies(the Community Multiscale Air Quality,CMAQ)to investigate regional NH_(3)emission sources and vertically resolved NH_(4)^(+)formation mechanisms during the winter in Beijing.Both stable nitrogen isotope analyses and CMAQ model suggest that combustion-related NH_(3)emissions,including fossil fuel sources,NH_(3)slip,and biomass burning,are important sources of aerosol NH_(4)^(+)with more than 60%contribution occurring on heavily polluted days.In contrast,volatilization-related NH_(3)sources(livestock breeding,N-fertilizer application,and human waste)are dominant on clean days.Combustion-related NH_(3)is mostly local from Beijing,and biomass burning is likely an important NH_(3)source(~15%–20%)that was previously overlooked.More effective control strategies such as the two-product(e.g.,reducing both SO_(2)and NH_(3))control policy should be considered to improve air quality.

Metre-size single-crystal graphene becomes a reality

Prof.Zhongfan Liu of Peking University,a well-known graphene researcher and also one of the authors for the work[1]highlighted here,has always said,‘‘Fabrication determines the future'.I agree.The growth of large-area high-quality graphene films is essential for the various uses of graphene materials in device applications.