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181.
The synthesis of 4‐(4'‐pyrimidinylmethyl)oxacyclohexan‐2‐one (2a) and 4‐(4'‐pyrimidinylmethyl)oxacycloheptan‐2‐one (3a) were achieved through the Michael addition of the anion derived from 4‐methylpyrimidine with oxacyclyo‐3‐hexen‐2‐one and oxacyclo‐3‐hepten‐2‐one respectively. These compounds 2a and 3a and their quaternary methiodide salts lack cholinomimetic activity.  相似文献   
182.
Environmental Science and Pollution Research - Oil spills can result in significant damage to marine estuaries, rivers, lakes, wetlands, and shorelines. Electrospun nanofibers containing...  相似文献   
183.
Environmental Science and Pollution Research - Malathion is a potent organophosphate insecticide that inhibits acetylcholinesterase (AChE) enzyme. Our experimental objective was to investigate the...  相似文献   
184.
Rapid socioeconomic development in the Linggi River Basin has contributed to the significant increase of pollution discharge into the Linggi River and its adjacent coastal areas. The toxic element contents and distributions in the sediment samples collected along the Linggi River were determined using neutron activation analysis (NAA) and inductively coupled plasma-mass spectrometry (ICP-MS) techniques. The measured mean concentration of As, Cd, Pb, Sb, U, Th and Zn is relatively higher compared to the continental crust value of the respective element. Most of the elements (As, Cr, Fe, Pb, Sb and Zn) exceeded the freshwater sediment quality guideline-threshold effect concentration (FSQG-TEC) value. Downstream stations of the Linggi River showed that As concentrations in sediment exceeded the freshwater sediment quality guideline-probable effect concentration (FSQG-PEC) value. This indicates that the concentration of As will give an adverse effect to the growth of sediment-dwelling organisms. Generally, the Linggi River sediment can be categorised as unpolluted to strongly polluted and unpolluted to strongly to extremely polluted. The correlation matrix of metal-metal relationship, principle component analysis (PCA) and cluster analysis (CA) indicates that the pollution sources of Cu, Ni, Zn, Cd and Pb in sediments of the Linggi River originated from the industry of electronics and electroplating. Elements of As, Cr, Sb and Fe mainly originated from motor-vehicle workshops and metal work, whilst U and Th originated from natural processes such as terrestrial runoff and land erosion.  相似文献   
185.
This paper highlights the levels of anions (nitrate, nitrite, sulfate, bromide, chloride, and fluoride) and cations (potassium, sodium, magnesium, and calcium) in selected springs and groundwater sources in the urban-west region of Zanzibar Island. The levels of total dissolved solids (TDS) and sodium adsorption ratio (SAR) were also studied. Thirty water samples were collected in December 2012 from various types of water sources, which included closed hand-dug wells (CHDW), open hand-dug wells (OHDW), springwater (SW), public bore wells (PBW), and bore wells owned by private individuals (BWP), and analyzed after filtration and sometimes dilution. The cations were analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES). The anions were analyzed by chemically suppressed ion chromatography (IC). The ranges of the levels of the investigated parameters were as follows: Na 13.68–3,656 mg L?1, K 2.66–583 mg L?1, Mg 0.63–131.10 mg L?1, Ca 16.79–189.9 mg L?1, Cl? 8.61–4,340.97 mg L?1, F? 0–1.02 mg L?1, Br? 0–10.88 mg L?1, NO3 ? 0.18–342.4 mg L?1, NO2 ? 0–1.39, SO4 2? 4.43–534.02 mg L?1, TDS 7–6,380 mg L?1, and SAR 0.63–50. Except fluoride, most of the studied parameters in the water samples had concentrations beyond the permissible limits of the World Health Organization (WHO). The elevated concentrations are a result of seepage of contaminated water from on-site septic tanks, pit latrines, landfill leachates, fertilizer applications, and domestic effluents. These results should alert domestic water stakeholders in Zanzibar to the urgent task of initiating a quick mitigation response to control these alarming water risks.  相似文献   
186.
Cd, Ni, Cr, Zn, Cu and Pb concentrations of muscle tissue of 61 fish samples belonging to six fish species (Sparus auratus, Pomatomus saltatrix, Sarda sarda, Engraulis encrasicholus, Sander lucioperca, Scomber scombrus) retailed in Kayseri, Turkey were determined by flame atomic absorption spectrometry after wet digestion. Cd concentrations of at least 31 fish samples (50.8%) and Pb concentrations of at least six fish samples (9.8%) exceeded the corresponding Turkish permissible limit of 0.05 and 0.2 mg kg(-1) respectively whereas Zn concentrations of 11 fish samples (18%) exceeded the Turkish Food Codex limits of 50 mg kg(-1) for Zn. Cu concentrations of all fish species analyzed (100%) were below the corresponding Turkish legislations of 20 mg kg(-1). No limits were established concerning Ni and Cr concentrations in fish by the Turkish governmental authorities.  相似文献   
187.
Heat stress presents a main problem to Muslim Hajeej (pilgrims) during Hajj (pilgrimage) season, particularly in summer. Records of the Saudi Ministry of Health show close relation between heat casualties and climatic heat load through consequent Hajj seasons. The present study was conducted to evaluate the climatic heat load in Hajj locations during summer of 1995 as well as just before and during the Hajj season of 1997. Heat measurements including: T (a), T (w), T (g), WBGT, relative humidity and air velocity were conducted through July-September 1995, and on March/April 1997, in 10 Hajj locations at morning, noon, afternoon and night. The highest WBGTs were at Haram court, Ghazzah area and Muna housing area, followed by Arafat areas and Muzdalefah, and the lowest at Azizia area. However, all the WBGTs were considerably higher than the ACGIH-TLV for safe heat exposure, particularly during daytime; meanwhile, heat exposure considerably exceeded the ASHRAE comfort zone at all locations all times. The natural climatic condition is a major contributing factor to the overall heat load; moreover, potentiated by heat dissipated from Hajj activities, including Hajeej crowds, human activities, and the vehicles' masses exhaust. This situation is further synergized by some pilgrims' misbehavior (e.g. living in open sunny areas, using vehicles without roofs) and lack of awareness of the seriousness of heat exposure among them. An outline for a control strategy has been suggested based on planting open areas of Arafat and Muna, provision of air conditioned housing and tents in Muna, segregation of pedestrians from vehicles and their provision of shaded roads and rest areas, establishing more water spatters in Arafat and Muna, checking the performance of large vehicles before issuing their permits for operation during Hajj, providing vehicles parking isolated areas away from Hajeej tents, provision of ample amounts of quality drinking water in all Hajj locations, provision of ample optimal ambulance services, and dissemination of educational information to Hajeej for their taking advantage of Fiqh (religion rules) waivers in performing Hajj rituals to minimize their heat exposure, and for their personal protection.  相似文献   
188.
Wastewater collection and treatment is quite important for sustainable management. It would be uneconomical and impractical to provide sewer systems and separate wastewater treatment plants (WWTP) for small communities. The decision process in wastewater planning is rather important in terms of comparing the alternatives considered. The two important points in the management of wastewater at rural areas not connected to a sewer system are to develop an optimized operation strategy and to make sure that the complete system is environmentally and economically sustainable. In some regions, package treatment could be an alternative solution. However, in cases where there is an existing large WWTP, a cluster system, where sewage generated by small communities could be transported via conveyors to a centralized WWTP, could be employed. In this study, the wastewater treatment and disposal problems in small communities were addressed and an alternative wastewater handling scenario was proposed. Additionally, three wastewater handling scenarios were compared. As a case study, Gebze villages were selected.  相似文献   
189.
Promoting the use of crumb rubber concrete in developing countries   总被引:3,自引:0,他引:3  
The use of accumulated waste materials in third world countries is still in its early phases. It will take courage for contractors and others in the construction industry to recycle selected types of waste materials in the concrete mixes. This paper addresses the recycling of rubber tires accumulated every year in Jordan to be used in concrete mixes. The main objectives of this research were to provide more scientific evidence to support the use of legislation or incentive-based schemes to promote the reuse of accumulated waste tires. This research focused on using crumb tires as a replacement for a percentage of the local fine aggregates used in the concrete mixes in Jordan. Different concrete specimens were prepared and tested in terms of uniaxial compression and splitting tension. The main variable in the mixture was the volumetric percentage of crumb tires used in the mix. The test results showed that even though the compressive strength is reduced when using the crumb tires, it can meet the strength requirements of light weight concrete. In addition, test results and observations indicated that the addition of crumb rubber to the mix has a limited effect toward reducing the workability of the mixtures. The mechanical test results demonstrated that the tested specimens of the crumb rubber concrete remained relatively intact after failure compared to the conventional concrete specimens. It is also concluded that modified concrete would contribute to the disposal of the non-decaying scrap tires, since the amount being accumulated in third world countries is creating a challenge for proper disposal. Thus, obliging authorities to invest in facilitating the use of waste tires in concrete, a fundamental material to the booming construction industry in theses countries, serves two purposes.  相似文献   
190.
In order to prevent ‘an impending neem failure’, from the incidence of the twin problems of the neem scale insect infestations and neem dieback, six authenticated provenances (Allahabad, Karnataka, Jodphur, Madinipur, Mukkambu and Annur), from the natural range of the species in India, were collected and appraised for survival in a degraded land in Kano, Nigeria. Established in a completely randomised block design with four replications, the trial was conducted with a view to restrengthening and/or replacing the already weakened Local Land Race of the species in the study area. There was a statistically significant difference in the survival of the seven provenances. The established differences are between Allahabad 83% (6.40 SEM), Mukkambu 83% (6.40 SEM), Annur 76% (4.90 SEM), Jodphur 63% (15.09 SEM) and Madinipur 56% (6.73 SEM), on the one hand, and Karnataka 17% (1.91SEM) and the Local Land Race, with 13% (0.13 SEM), on the other hand. The research recommends Allahabad and Mukkambu 83% (6.40 SEM) based on this outstanding performance.  相似文献   
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