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271.
The goal of this study was to investigate the activity of the coagulant extracted from the cactus Opuntia ficus-indica (OFI) in the process of coagulation/flocculation of textile effluents. Preliminary tests of a kaolinite suspension achieved maximum turbidity removal of 95 % using an NaCl extraction solution. Optimization assays were conducted with actual effluents using the response surface methodology (RSM) based on the Box–Behnken experimental design. The responses of the variables FeCl3, dosage, cactus dosage, and pH in the removal of COD and turbidity from both effluents were investigated. The optimum conditions determined for jeans washing laundry effluent were the following: FeCl3 160 mg L?1, cactus dosage 2.60 mg L?1, and pH 5.0. For the fabric dyeing effluent, the optimum conditions were the following: FeCl3 640 mg L?1, cactus dosage 160 mg L?1, and pH 6.0. Investigation of the effects of the storage time and temperature of the cactus O. ficus-indica showed that coagulation efficiency was not significantly affected for storage at room temperature for up to 4 days.  相似文献   
272.
A nationwide programme for the prevention of sickle cell (SS and SC) disorders was initiated in Cuba in 1983. Couples at risk were identified by screening pregnant women and the partners of those who carry an abnormal haemoglobin, followed by genetic counselling and the offer of prenatal diagnosis. Prenatal diagnosis was performed in one laboratory, which had carried out 1068 prenatal tests for Hb SS and SC disorders by the end of 1992. The centralization of the service has permitted rapid identification and resolution of problems.  相似文献   
273.
发展中国家中正面临经济发展挑战的那些人口密集的流域盆地和海岸带地区可能会在各种问题上受到中度或严重的环境影响.这些由巴西东北部至南部流向大西洋海岸的汇水盆地包括广阔的气候带和多种生态系统.盆地边界以内分布着大西洋雨林、大范围的半干旱热带旱生林(caatinga)、广阔的树木及灌木林地(cerrado)、巴西6670km 海岸线的一大部分及其海洋生态系统.在过去的几十年中,这些自然资源上的人类活动不断发展.海滨化已给沿海生境及生物群落造成了沉重的负担.caatinga和cerrado中的大部分原生植被遭到了破坏,仅存留了7%的大西洋原始雨林.河口、海湾和沿海泻湖也遭到了无法恢复的破坏.土地使用、筑坝和分水等活动已成为造成生境丧失和水生生态系统改变的主要原因.尽管巴西东北部地区的干旱和东南部及南部地区的富庶和工业化之间形成明显反差,但给上述两种地区的生境和生物群落造成的影响是同样严重的.阻止环境恶化的努力没有见到效果.为此建议,应该实行将重点集中在水生生态系统完整性的一些更加综合性的环境政策,而不是把重点单独地集中在自然资源上.  相似文献   
274.
With the aim of estimating the chemical composition of bulk precipitation (wet + dry) in Cubat?o, rainwater samples were collected at several localities in the Cubat?o region from May 1984 to October 1985. The levels of some inorganic ions (Na+, Ca2+, K+, Mg2+, Cl-, SO4(2-), NH4+, PO4(3-)) were measured by atomic absorption spectrophotometry, turbidimetry and titration analysis. Correlation and Fisher discrimination indices, principal component and varimax loading and scores were determined in the multivariate statistical data treatment. The results showed that ionic concentrations in rainwater from Vila Parisi are significantly higher than those of Cubat?o Centro, Santos and Serra do Mar. The ionic compositions of the Vila Parisi rainwater seem to be mainly determined by local anthropogenic activities (industrial pollution). Besides the influence of this factor on water quality, there is also a natural oceanic contribution involving Cl- and Na+ at the other locations.  相似文献   
275.
Photodegradation of an azo dye of the textile industry   总被引:2,自引:0,他引:2  
An advanced oxidation treatment, UV/H2O2, was applied to an azo dye, Hispamin Black CA, widely used in the Peruvian textile industry. Rates of color removal and degradation of the dye have been evaluated. A strongly absorbing solution was completely decolorized after 35 min of treatment, and after 60 min an 82% reduction of the total organic carbon (TOC) was obtained. It has been found that the degradation rate increased until an optimum value, beyond which the reagent exerted an inhibitory effect. The degradation rate was also function of pH.  相似文献   
276.
Castromil is one of the gold mining areas in Portugal that has been abandoned since 1940. This area, which was first mined in Roman times, is located within a Hercynian granite body near the contact with Silurian metasediments. Gold is essentially disseminated along veins in the silicified granite, running NW-SE, related with a shear zone and frequently associated with sulphides (arsenopyrite and basically pyrite). In paragenetic terms, three stages of mineralization are considered: ferro-arseniferous (quartz + arsenopyrite I + pyrite I + pyrrhotite + bismuth), zinciferous (sphalerite + chalcopyrite), and remobilization (arsenopyrite II + galena + gold). Due to the lack of laws and environmental education, Castromil is today a gold mining heritage site where we can detect the consequences of an incautious exploration (tailings, wells and adits located in the old explored zone) and where a residential area is located. In order to characterize the actual state of the old mining area the trace metal contamination of soils and waters by mining activities was investigated. In the studied area 106 soil samples, 15 waters and 20 plants were sampled and analysed. The soil samples were analysed for 32 elements by ICP-AES. Waters were analysed by ionic chromatography and ICP-MS for major and trace elements. Plants were analysed for As, Fe and Pb by AAS. The results are discussed taking into account the risk-based standards for soils and groundwater's (target and intervention values) proposed by Swartjes (1999). The results show elevated concentration of As and Pb which were found in soils collected from agricultural areas. Foodstuff plants species collected in the Castromil agricultural area show high concentrations of As in the leaves (cabbage and lettuce) and in the tubers (potatoes). Groundwaters in the mining area contain high concentrations of As that exceeds the intervention values. The area must to be subject to a remediation process, considering the actual risks to humans and ecosystems and the risks due to contaminant migration.  相似文献   
277.
Green lacewings in the carnea group of Chrysoperla engage in species-specific heterosexual duets using low-frequency substrate-borne signals. Within each species, both sexes sing nearly identical songs. Songs are the principal barriers to hybridization between sympatric species in the complex. Here, we investigated the responsiveness of males and females of Chrysoperla plorabunda to synthesized, prerecorded songs that differed from the species mean in the period between repeated volleys of abdominal vibration. We tested 15–16 males and 15–16 females using playbacks of two signals that gradually increased or decreased in volley period, starting at the species mean. We found that (1) duets during courtship are accurate, interactive, and adjustable by each participant; (2) in staged duets, both sexes respond best to song tempos near the mean volley period of their population, but can nonetheless maintain duets with signals of nearly twice, or half, the normal volley period; (3) individuals fine-tune their adjustments to signals of different volley periods by changing their own volley duration and latent period, or less often by inserting extra volleys or skipping every other volley; (4) males are significantly better at matching signals of changing tempo than females; and (5) the range of song responsiveness of C. plorabunda does not overlap the natural range of volley periods found in Chrysoperla adamsi, an acoustically similar sibling species, thus reaffirming strong behavioral isolation. In sum, the precise, almost unbreakable heterosexual duets characteristic of song species of the carnea group result from tight mutual feedback between partners. Effective reproductive isolation between species can be based on song differences alone.  相似文献   
278.
The Science of Nature - Female-only colour polymorphism is rare in birds, but occurs in brood parasitic cuckoos (Cuculidae). Obligate brood parasites leave incubation and parental care to other...  相似文献   
279.
The insect immune system faces various challenges; particularly in social bees, caste system and age polyethism expose individuals to numerous environmental and working conditions. However, little is known about how cellular defenses in social bees may be organized to respond to a variety of immune challenges. Here, we describe the morphological features and the total and differential counts of hemocytes in different female classes (newly emerged workers, nurses, foragers, and virgin queens) of the eusocial stingless bee Melipona quadrifasciata. Granulocytes and prohemocytes were, respectively, the most and the least abundant cells among all classes of females. Furthermore, there were more prohemocytes in virgin queens than in foragers. The total number of hemocytes was smaller in foragers, whereas the largest number was observed in nurse workers. This reduced amount of hemocytes in foragers might allow energy savings to perform colony activities such as foraging and defense. Foragers also had the biggest hemocytes (either prohemocytes, granulocytes, or plasmatocytes) in comparison to the other classes of females, which might have arisen as a compensation for the reduction in number of these cells during aging. These results suggest that profiles of hemocytes of M. quadrifasciata vary according to the caste and age of this eusocial bee.  相似文献   
280.
The effects of different salinity levels (28, 34 and 40‰) on functional responses of Chamelea gallina haemocytes were evaluated in a two part study dealing with modulations of immune parameters. This part (Part II) of the study was focused on the superoxide dismutase (SODs) activity and expression in haemocyte lysate and cell-free haemolymph. Results of this study established that the exposure of C. gallina specimens at 40‰ salinity provoked a decrease in Mn-SOD and Cu/Zn-SOD activities in haemocyte lysate suggesting a declining superoxide anion generation at the highest salinity tested. Expression of MnSOD was coherent with activity values, while Cu/ZnSOD showed two immunoreactive bands. The former corresponds to the cytosolic Cu/Zn-SOD (16 kDa) was not coherent with the enzyme activity and the second (28–30 kDa) probably attributed to EC-SOD. In cell-free haemolymph, Mn-SOD activity decrease and Cu/Zn-SOD activity increase at 40‰ were observed, likely due to EC-SOD contribution, strongly induced at the same salinity. After EC-SOD detection with two different antibody, we postulate that the EC-SOD like-protein band (29 kDa) may be constitute partly by EC-SOD and probably by Cu/Zn-SOD dimeric form not completely dissociated under reducing condition or a Cu/Zn-SOD degenerated but still recognized by antibody. The cell-free haemolymph increase of EC-SOD at high salinity values plays an important role in immune defence of C. gallina. According to the conclusion of Part I of this study, our data confirmed the destabilizing effect of 40‰ salinity on haemocyte functionality, while to 28‰ exposure, data don’t confirm its stressful action as instead stated by results of Part I. Further studies are necessary to clear up this discrepancy.  相似文献   
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