307 resultados para 1252
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工业的高速发展使地球上有限的水资源受到日益严重的污染,去除水中的有毒、有害化学物质已成为环保领域的一项重要工作。纳米材料与技术的开发应用为实现高效、低成本的水处理开辟了新的途径。 本课题组开发的纳米-亚纳米功能新材料(生态宝)可用作养殖生态环境改良剂,它对“三氮”、硫化物、CODCr、BOD5、重金属等有害物质具有很好的去除能力。生态宝用于养殖幼参,有显著的促生长、增加成活率的作用。生态宝用于养殖对虾,对虾体内重金属含量有明显降低。 以粉末状P25型纳米TiO2为光催化剂,系统的研究了它对染料AB80的光催化降解。在紫外光照射下,光催化反应75min,染料AB80溶液完全脱色,光催化反应135min,染料溶液完全矿化;AB80的光催化脱色反应遵从准一级反应动力学;催化剂的最佳剂量为1.0g/L。AB80在TiO2颗粒表面的吸附符合Langmuir方程式,随着pH值的增加吸附量迅速减少;pH值在反应中起着重要的作用,碱性溶液中的反应速度比酸性溶液的大,pH=10.0初始反应速度最大;电子捕获剂(H2O2)的加入能够显著的提高反应速率,H2O2浓度为5mmol/L时,反应速度变为原来的2.78倍。 以硅藻土为载体,采用溶胶-凝胶法制备了负载型的纳米TiO2,SEM分析结果表明,TiO2的包覆量对负载光催化剂的形貌有很大影响,TiO2包覆量较低(14.5%)的复合物无团聚现象发生。XRD分析结果表明,所制备的TiO2为锐钛矿和金红石混晶型,平均粒径11nm。FT-IR分析结果表明,TiO2和硅藻土之间没有生成化学键。以染料AB80和B-2BF为模型污染物,利用制备的光催化剂复合物进行了吸附-光催化试验,结果表明,TiO2包覆量为14.5%的复合物具有较高的吸附-光催化活性,对模型污染物的降解效果好于德国Degussa公司的商品纳米P25-TiO2。溶液pH对TiO2/硅藻土复合物光催化活性影响很大,弱酸性条件有利于反应的进行。TiO2/硅藻土对实际印染废水有较好的降解效果,试验条件下,废水光催化反应3.5h,色度去除率为100%。研究了液固多相光催化反应的催化剂失活原因及再生手段,提出TiO2/硅藻土复合物再生的方法为酸洗和高温烧结。对于模拟印染废水来说,光催化剂重复使用对光催化活性几乎没有影响,重复使用15次后,催化活性仅降低了12%。而对实际印染废水来说,重复使用对光催化活性有影响,光催化剂复合物重复使用7次后,催化活性降低了41%。TiO2/硅藻土复合光催化剂成本低,简便易行,光催化效果好,有望在环境污染物治理中得到广泛的应用。 采用CuCl水解法制得了硅藻土负载的纳米Cu2O,并利用XRD、SEM等手段对其进行表征。研究了负载的纳米Cu2O对B-2BF和AB80染料废水的光催化降解,发现纳米Cu2O经过负载后,团聚减少,分散性好,对染料废水的光催化降解效率成倍增长。纳米Cu2O包覆量为31.3%的光催化剂复合物光催化活性最好,其光催化效率是纯的Cu2O的6倍。负载的纳米Cu2O可以有效的利用太阳光进行光催化反应,而且太阳光下纳米Cu2O的光催化活性比纳米TiO2的强。太阳能是取之不尽、用之不竭的清洁能源,利用太阳能来处理染料废水成本低、无污染,是一种非常有发展前景的环境治理新技术。pH 5-pH 7是负载纳米Cu2O光催化降解B-2BF的最佳反应范围。负载的纳米Cu2O光催化剂有较好的稳定性,重复使用8次以后,其脱色率仍能达到75%以上。
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The disjunct distribution of forests in the Qinghai-Tibetan Plateau (QTP) and adjacent Helan Shan and Daqing Shan highlands provides an excellent model to examine vegetation shifts, glacial refugia and gene flow of key species in this complex landscape region in response to past climatic oscillations and human disturbance. In this study, we examined maternally inherited mitochondrial DNA (nad1 intron b/c and nad5 intron 1) and paternally inherited chloroplast DNA (trnC-trnD) sequence variation within a dominant forest species, Picea crassifolia Kom. We recovered nine mitotypes and two chlorotypes in a survey of 442 individuals from 32 populations sampled throughout the species' range. Significant mitochondrial DNA population subdivision was detected (G(ST) = 0.512; N-ST = 0.679), suggesting low levels of recurrent gene flow through seeds among populations and significant phylogeographical structure (N-ST > GST, P < 0.05). Plateau haplotypes differed in sequence from those in the adjacent highlands, suggesting a long period of allopatric fragmentation between the species in the two regions and the presence of independent refugia in each region during Quaternary glaciations. On the QTP platform, all but one of the disjunct populations surveyed were fixed for the same mitotype, while most populations at the plateau edge contained more than one haplotype with the mitotype that was fixed in plateau platform populations always present at high frequency. This distribution pattern suggests that present-day disjunct populations on the QTP platform experienced a common recolonization history. The same phylogeographical pattern, however, was not detected for paternally inherited chloroplast DNA haplotypes. Two chlorotypes were distributed throughout the range of the species with little geographical population differentiation (G(ST) = N-ST = 0.093). This provides evidence for highly efficient pollen-mediated gene flow among isolated forest patches, both within and between the QTP and adjacent highland populations. A lack of isolation to pollen-mediated gene flow between forests on the QTP and adjacent highlands is surprising given that the Tengger Desert has been a geographical barrier between these two regions for approximately the last 1.8 million years.
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Petroleum and Natural Gas is an important strategic resources. The reserves of Petroleum and Natural Gas can’t meet the need of our country, which also blocks the development of economy and threatens the safety of national. Therefore, it makes a great sense to bring “the second round of oil & gas exploration” into effect and study the exploration of oil and gas of Pre-Cenozoic residual basins in China. The integrated geophysical exploration is the main way to research the Pre-Cenozoic residual basins. Gravity exploration is one of the most important exploration methods, which has played an important role in oil and gas prospecting, such as compartmentalizing geotectonic elements, delineating the distribution range of sedimentary basins, searching oil and gas structure, abstracting oil and gas information, and so on, from its naissance. The isostatic gravity anomalies is significant for exploration, which can help us research deep crustal structure, the equilibrium state of earth, the geologic structure of shallow crust, the basement shape of sedimentary basins and the genetic evolution of sedimentary basins. In the paper, we stress the implication and physical meanings systemically, and discuss the calculation theory. On the basis of previous work, we test different isostatic compensation models and parameters to find out their influences to the result of isostatic gravity anomalies. In addition, we improve the method of isostatic gravity anomalies calculation and give a system of isostatic gravity anomalies calculation which is proved has satisfying effect. From the research above, we find that the results of Platt model and Airy model are consistent, which have similar form and almost the same value. However, by contrast, the Airy model is proved has better adaptability than Platt model. The two main parameters——crust thickness and density difference of crust and mantle, both have influence to the isostatic gravity anomalies, but the latter have more. Finally, we adopt the regional field extending edge method to make the result more of actual geologic condition. On the methods above, we calculate the isostatic gravity anomalies field in Yellow Sea area from the Bouguer gravity anomalies and the water depth and altitude data. And then the isostatic gravity anomalies character is analyzed and the integrated geological-geophysical interpretation is made on the basis of summarizing the previous research result systemically and analyzing other geophysical data and geological information. From the research, we find that the Yellow Sea area belongs to continental type crust equilibrium regions, where the isostatic gravity anomalies field is placid and has less fluctuation values, which implies that the area is in equilibrium state to different extends.
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This year, as the finale to the Artificial Intelligence Laboratory's annual Winter Olympics, the Lab staged an AI Fair ??night devoted to displaying the wide variety of talents and interests within the laboratory. The Fair provided an outlet for creativity and fun in a carnival-like atmosphere. Students organized events from robot boat races to face-recognition vision contests. Research groups came together to make posters and booths explaining their work. The robots rolled down out of the labs, networks were turned over to aerial combat computer games and walls were decorated with posters of zany ideas for the future. Everyone pitched in, and this photograph album is a pictorial account of the fun that night at the AI Fair.
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Huws, B. (2000). Awdl Foliant Ddienw i Syr Dafydd Hanmer. Dwned. 6, pp.43-64.
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Tugann an staidéar taighde aghaidh ar an dátheangachas i bPoblacht na hÉireann agus go háirithe ar thuairimí dhaoine óga dátheangacha sa 21ú haois. Is é cuspóir an staidéir ná iniúchadh a dhéanamh ar mheonta déagóirí Éireannacha dátheangacha i leith na Gaeilge agus a gcuid aitheantais mar dhéagóirí dátheangacha. Déanann an staidéar anailís ar mheonta daltaí a fhreastalaíonn ar iar-bhunscoileanna lán-Ghaeilge. Féachtar ar thuairimí tuismitheoirí, múinteoirí agus iar-scoláirí freisin. Is í príomhcheist an staidéir seo ná: Cad iad meonta déagóirí Éireannacha dátheangacha i leith teanga na Gaeilge agus cad iad a n-aitheantais mar Éireannaigh óga dátheangacha? Baineadh úsáid as modhanna cáilíochtúla idir agallaimh, agallamh grúpa, scríbhneoireacht phearsanta agus ríomhphoist chun eolas a bhailiú i scoil an staidéir cháis. Roghnaíodh modh cainníochtúil an cheistneora náisiúnta chun cur leis an eolas. Tugann an taighde le tuiscint go mothaíonn déagóirí Éireannacha dearfach faoi theanga na Gaeilge agus faoin a gcuid aitheantais mar dhaoine dátheangacha. Léiríonn torthaí an taighde gurb ionann teanga na Gaeilge dóibh agus seoid luachmhar a sholáthraíonn buntáistí, deiseanna agus féidearthachtaí dóibh. Maidir le cruthú aitheantais, chuaigh formhór na ndéagóirí i scoil an staidéir cháis i dtreo a ndá ghrúpa teangeolaíochta agus chruthaigh siad “linguistic brokerage” (Shenk, 2008) a tharraing a taobh Gaelach is Béarla le chéile. Mothaíonn formhór na ndéagóirí dátheangacha seo go bhfuil aitheantas amháin acu ach go bhfuil an dá theanga, an dá chultúr agus an dá pháirt dá saoil mar pháirt den gcomhaitheantas sin. Ach ba léir go raibh éagsúlachtaí i measc na rannpháirtithe freisin. Tacaíonn torthaí an taighde le gnéithe den litríocht ar a rinneadh athbhreithniú chun ról lárnach na teanga i gcruthú aitheantais an déagóra a léiriú. Cuireann an taighde seo leis an réimse toisc go soláthraíonn sé eolas luachmhar agus fiúntach faoin dátheangachas agus aitheantas i bPoblacht na hÉireann sa 21ú haois.
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© 2015. American Geophysical Union. All Rights Reserved.The role of surface and advective heat fluxes on buoyancy-driven circulation was examined within a tropical coral reef system. Measurements of local meteorological conditions as well as water temperature and velocity were made at six lagoon locations for 2 months during the austral summer. We found that temperature rather than salinity dominated buoyancy in this system. The data were used to calculate diurnally phase-averaged thermal balances. A one-dimensional momentum balance developed for a portion of the lagoon indicates that the diurnal heating pattern and consistent spatial gradients in surface heat fluxes create a baroclinic pressure gradient that is dynamically important in driving the observed circulation. The baroclinic and barotropic pressure gradients make up 90% of the momentum budget in part of the system; thus, when the baroclinic pressure gradient decreases 20% during the day due to changes in temperature gradient, this substantially changes the circulation, with different flow patterns occurring during night and day. Thermal balances computed across the entire lagoon show that the spatial heating patterns and resulting buoyancy-driven circulation are important in maintaining a persistent advective export of heat from the lagoon and for enhancing ocean-lagoon exchange.
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El objetivo principal de este trabajo surge por la inquietud de estudiantes y profesores de Institutos de Educación Universitaria en Venezuela (Universidad Simón Bolívar, Universidad Nacional Abierta, Universidad Nacional Experimental de las Fuerzas Armadas, Universidad Pedagógica, entre otras); así como también los comentarios de algunos colegas de Universidades en Costa Rica y República Dominicana, donde se observa con gran preocupación el rechazo que presentan y plantean muchos profesores en el área de las matemáticas al uso e implementación de las tecnologías en sus programas y contenidos programáticos. Luego de realizar los estudios y corroborar el grado de analfabetismo tecnológico existente en los profesores de matemática, se consideraron elaborar cursos, diplomados y talleres para involucrar a nuestros docentes en el uso de las tecnologías.
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In power electronics modules, heavy aluminium wires, i.e. wire diameters greater than 100 microns, are bonded to the active semiconductor devices and conductor metallization to form electric circuits of the power electronic module. Due to the high currents that may flow through these wires, a single connection usually contains several wires and thus, a large number of wires are used in a power electronics module. Under normal operation or test condition, a significant amount of stresses and strains induced in the wire and bonding interfaces, resulting in failure over time. In this paper, computer modelling techniques are used to analyse the effect of globtop design on the reliability of aluminium wirebonds under cyclic thermal-mechanical loading conditions. The results will show the sensitivity of the reliability of the wirebonds to the changes in the geometry and the material properties of the wirebond globtop.
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Spawning temperature preferences for sardine (Sardina pilchardus) in the eastern North Atlantic were determined from field data. These were compared with climatological temperature cycles (1986-2002) derived from satellite data by geographical region, to predict spawning seasons. Optimum spawning temperatures were determined as 14.0-15.0oC from the English Channel to Portugal and 16.0–18.0oC for all north-west African regions. Spawning seasons were closely related to the general latitudinal trend of the annual temperature cycle, with modification by upwelling in the western Iberian and north-west African regions. Some differences between temperature-based spawning season predictions and field observations were related to variations in seasonal plankton production. Correlations in the annual time-series of favourable spawning temperatures suggested relatively strong linkages between the southern areas from Portugal to Senegal. There was no consistent relationship between annual variations in duration of temperature-predicted spawning seasons and observed field abundance of eggs.