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241.
The concentrations and distribution of the elements, including heavy metals such as As, Ba, Br, Co, Cr, Cs, Fe, Ga, K, Mn, Na, Rb, Sc, Sr, Th and Zn, were investigated in dated sediment cores of Nainital Lake located in the Himalayan region, in Uttar Pradesh state of India, which is considered as a remote background area. The concentrations of the elements were measured by instrumental neutron activation analysis using the k0 method. The International Atomic Energy Agency certified reference material SL-3 was used to evaluate the accuracy of the method. The normalized data for a series of elements were used to understand the source of loading. Elements like Br, Co, Cr, Fe, K, Mn and Zn show a negative correlation with increasing depth whereas elements like As, Ba, Cs, Na and Rb show a positive correlation with increasing depth. By considering the concentration for the bottom segments of the core as close to the baseline concentration, recent flux values for different elements were calculated. An increase in the flux value was observed for Br, Cr, Fe, K, Mn and Zn, which can be attributed to anthropogenic contribution in recent years.  相似文献   
242.
本文讨论了有关能源的思想观念的演变.20年前当几位作者开始携手合作研究能源时,人们一般是以发展的眼光、从供应方的角度来考虑能源问题,将注意力集中到消费趋势以及如何扩大供给以满足不断增长的需求上.这种方法在能源利用的环境影响、安全性和公平合理性方面的研究局限深深地困扰着他们.例如,大约有20亿人口经济条件有限,买不起现代能源,这严重限制了他们生活水平的提高.此外,能源还是造成环境问题的重要因素,其中包括室内空气污染、城市空气污染、酸化和全球气候变暧等.笔者认为,应当树立新的能源供给观念,使能源的供给方式有助于解决这些严重问题.笔者主张,能源必须成为推进可持续发展——经济上可行、以需要为导向、自力更生的能及无损于环境的发展——的工具,而且,应当将研究重点放在能源的终端用途上和能源供应的服务上.有助于实现可持续发展目标的能源技术方案也在本文进行了讨论.文中强调了制订和运用新型能源技术解决方案的必要性.笔者以巴西乙醇的利用为例,阐述了使发展中国家避免重复工业化国家所犯错误而在技术上实现跨越式发展的可能性.文中还重点介绍了在发展中国家引进先进技术过程中外国直接投资可能起到的作用,阐述了农村能源的近期和远期战略.最后,介绍了促进能源系统的发展,使之与可持续发展的步调一致并且支持可持续发展的相关政策.  相似文献   
243.
One ‘erroneous’ diagnosis occurred in 200 first-trimester chorionic villus samples (CVS) analysed. In direct preparations following 24 h incubation as well as in long-term cultures, a 46.XX karyotype was observed in the villi (28 and 25 cells, respectively). At 20 weeks of gestation, labour was induced because of fetal death in utero. An autopsy performed on the fetus revealed a male phenotype. Placenta and fetal tissues were not submitted for cytogenetic studies. The discordant CVS karyotype (46,XX), in view of the male fetal phenotype, prompted further cytogenetic and molecular studies. Chromosome marker studies on the parents' blood and chorionic villi confirmed both maternal and paternal inheritance of chromosomes in the CVS. DNA studies on formalin-fixed skin using a Y-specific probe, DYZ1, confirmed the presence of a Y chromosome in the fetus. The most likely cause of the discrepant CVS karyotype is the presence of an undetected degenerating dizygotic twin.  相似文献   
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The structure and properties of chicken feather barbs makes them unique fibers preferable for several applications. The presence of hollow honeycomb structures, their low density, high flexibility and possible structural interaction with other fibers when made into products such as textiles provides them unique properties unlike any other natural or synthetic fibers. No literature is available on the physical structure and tensile properties of chicken feather barbs. In this study, we report the physical and morphological structure and the properties of chicken feather barbs for potential use as natural protein fibers. The morphological structure of chicken feather barbs is similar to that of the rachis but the physical structure of the protein crystals in chicken feather barbs is different than that reported for feather rachis keratin. The tensile properties of barbs in terms of their strength and modulus are similar but the elongation is lower than that of wool. Using the cheap and abundant feathers as protein fibers will conserve the energy, benefit the environment and also make the fiber industry more sustainable  相似文献   
247.
Fetal death occurs in 15% of clinically recognized pregnancies. Cytogenetic abnormalities are present in 50% of spontaneous abortions (fetal deaths < 20 weeks) whereas the rate is 6% to 13% for stillbirths (fetal deaths ≥ 20 weeks). Microarray has been demonstrated to increase the diagnosis of genetic abnormalities by providing coverage of the entire genome at a higher density, detecting as small as 50 to 100 kb deletions or duplications, known as copy number changes. Microarray is particularly suited for evaluation of fetal death because DNA can still be analyzed in macerated fetuses and nonviable tissue, two situations where culturing and karyotyping is known to have low yield. Microarray has already proven successful in providing additional genetic information beyond karyotype in spontaneous abortion. The few studies on the use of microarray in stillbirth evaluation have been promising, demonstrating an increase in the diagnosis of clinically relevant genetic abnormalities when compared with karyotype. As the cost and technology improve, microarray may ultimately become the first line screen for genetic abnormalities in stillbirth. The accurate diagnosis of a genetic abnormality as the cause for fetal death may provide closure for families, prevent unnecessary treatments, and enable clinicians to more accurately counsel and manage subsequent pregnancies. © 2012 John Wiley & Sons, Ltd.  相似文献   
248.
Aetiological understanding and screening methods for congenital heart disease (CHD) are limited. Maternal metabolomic assessment offers the potential to identify risk factors and biomarkers. We performed a systematic review (PROSPERO CRD42022308452) investigating the association between fetal/childhood CHD and endogenous maternal metabolites. Ovid-MEDLINE, Ovid-EMBASE and Cochrane Library were searched between inception and 06/09/2022. Case control studies included analysing maternal blood or urine metabolites in pregnancy or postpartum where there was foetal/childhood CHD. Risk of bias assessment utilised the Scottish Intercollegiate Guidelines Network methodology checklist and narrative synthesis was performed. A total of 134 records were screened with eight eligible studies (n = 3242 pregnancies, n = 842 CHD-affected offspring). Five studies performed metabolomic analysis in pregnancy. Metabolites distinguishing case and control groups spanned lipid, glucose and amino-acid pathways, with the development of sensitive risk prediction models. No single metabolite consistently distinguished cases and controls across studies. Three studies performed targeted analysis postnatally with altered lipid and amino acid metabolites and raised homocysteine and markers of oxidative stress identified in cases. Included studies reported small sample sizes, analysing different biosamples at variable time points using differing techniques. At present, there is not enough evidence to confidently associate maternal metabolomic profiles with offspring CHD risk. However, several identified pathways warrant further investigation.  相似文献   
249.
The five largest social safety net (SSN) programmes in the world are being implemented in India, China and Brazil. Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA) is one of these programmes and regarded as the world’s largest SSN. MGNREGA aims at enhancing livelihood security of households in rural India by providing guaranteed wage employment. The scheme has resulted in the creation of sustainable assets that promote the economic and infrastructure development. More than 33 million assets were built in the process of MGNREGA. These assets were spread out in 262,380 smallest units of administration covering 6887 sub-districts with the participation of more than 250 million human manpower. The Sustainable Development Goals (SDG) aims to end poverty, protect the planet and ensure that all people enjoy peace and prosperity. The 17 goals tackle the root cause of poverty and attempts to make a positive change for both people and planet. Ecological regeneration or rejuvenation during the development of the assets generated numerous tangible and intangible benefits to the community in a sustainable way. MGNREGA, a federal government-sponsored scheme, using a decentralized approach is directly or indirectly helping to achieve all the 17 goals of sustainable development in India. This article takes a holistic approach to correlate and map the concepts and outcomes of MGNREGA programme with SDG. This article emphasises the fact that community-based participation in the planning and development activities at the regional levels will yield benefits to the biosphere, society and economy at the national level.  相似文献   
250.
Studies about wetlands have been identified as a key component of environmental change. The present study assesses the spatio-temporal changes in the wetlands of the Great Rann of Kachchh, in the Kachchh Biosphere Reserve, India, using remote sensing and GIS techniques. Satellite time-series data from Landsat (1977, 1990 and 1999) and IRS P6 (2006, 2008–2012) were used. The Normalised Difference Water Index (NDWI) was derived for each year and the layers were manually edited to obtain a high classification accuracy. The analysis found that the area has undergone considerable change from 1977 to 2011. The natural wetland area of 30.6 km2 was converted to salt pans. An area of about 255 km2 (41.6 %) of natural grassland was invaded by Prosopis juliflora, which raises further conservation concerns and emphasises the importance of having intervention plans to manage this ecosystem. The highest water spread of 1171 km2 was observed in September 2011, followed by 2010, 2009 and 2008 in the same month. The present study is useful in planning the long-term management and conservation of the Great Rann of Kachchh wetland.  相似文献   
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