989 resultados para 7038-507
Resumo:
This study investigates the landscape evolution and soil development in the loess area near Regensburg between approximately 6000-2000 yr BP (radiocarbon years), Eastern Bavaria. The focus is on the question how man and climate influenced landscape evolution and what their relative significance was. The theoretical background concerning the factors that controlled prehistoric soil erosion in Middle Europe is summarized with respect to rainfall intensity and distribution, pedogenesis, Pleistocene relief, and prehistoric farming. Colluvial deposits , flood loams, and soils were studied at ten different and representative sites that served as archives of their respective palaeoenvironments. Geomorphological, sedimentological, and pedological methods were applied. According to the findings presented here, there was a high asynchronity of landscape evolution in the investigation area, which was due to prehistoric land-use patterns. Prehistoric land use and settlement caused highly difIerenciated phases of morphodynamic activity and stability in time and space. These are documented at the single catenas ofeach site. In general, Pleistocene relief was substantially lowered. At the same time smaller landforms such as dells and minor asymmetric valleys filled up and strongly transformed. However, there were short phases at many sites, forming short lived linear erosion features ('Runsen'), resulting from exceptional rainfalls. These forms are results of single events without showing regional trends. Generally, the onset of the sedimentation of colluvial deposits took place much earlier (usually 3500 yr BP (radiocarbon) and younger) than the formation of flood loams. Thus, the deposition of flood loams in the Kleine Laaber river valley started mainly as a consequence of iron age farming only at around 2500 yr BP (radiocarbon). A cascade system explains the different ages of colluvial deposits and flood loams: as a result of prehistoric land use, dells and other minor Pleistocene landforms were filled with colluvial sediments. After the filling of these primary sediment traps , eroded material was transported into flood plains, thus forming flood loams. But at the moment we cannot quantify the extent ofprehistoric soil erosion in the investigation area. The three factors that controlled the prehistoric Iandscapc evolution in the Ioess area near Regensburg are as follows: 1. The transformation from a natural to a prehistoric cultural landscape was the most important factor: A landscape with stable relief was changed into a highly morphodynamic one with soil erosion as the dominant process of this change. 2. The sediment traps of the pre-anthropogenic relief determined where the material originated from soil erosion was deposited: either sedimentation took place on the slopes or the filled sediment traps of the slopes rendered flood loam formation possible. Climatic influence of any importance can only be documented as the result of land use in connection with singular and/or statistic events of heavy rainfalls. Without human impact, no significant change in the Holocene landscape would have been possible.
Resumo:
Constituintes fazem um balanço das mudanças do Poder Judiciário. Plenário derruba a criação de um Conselho para fiscalizar a Justiça. Com a jornada tripla de trabalho, os Constituintes estão quase terminando a votação do Poder Judiciário, só falta apreciar os destaques sobre o Ministério Público. Constituintes garantiram um direito às categorias sem federações estaduais de participar da indicação de juízes classistas na Justiça do Trabalho. Serão criados tribunais militares nos estados onde a força policial militar for superior a 20 mil homens, embora alguns constituintes não tenham concordado com a medida. Também foi aprovada uma emenda que dá poderes aos Tribunais Federais Regionais para julgar recursos contra decisões de juízes federais. O Plenário derrubou a criação do Conselho Nacional de Justiça, um órgão para fiscalizar o Poder Judiciário. Os constituintes fazem um balanço do Poder Judiciário. A maioria concorda que houve avanços e modernização na Justiça. O Tribunal Federal de Recursos é extinto e o Superior Tribunal de Justiça assume os recursos provenientes dos estados.
Resumo:
溶剂分馏萃取是分离、提纯、富集物质的有效方法之一,由于它具有分离效果好,易于操作等优点。因此,在稀土萃取分离工艺中得到了广泛的应用。但是,每个分馏萃取工艺只能分离两个组份,若要分离所有稀土元素,流程较长。为改进生产,本工作提出了一种三出口萃取分离工艺流程。这种工艺流程可视为由两个萃取段和两个洗涤段组成,由于在两个洗涤段中,两相稀土浓度较高、稀土交换量较大,故可使级数减少。采用此工艺流程进行了P_(507)萃取分离Gd、Tb、Dy三组元素的串级模拟实验,得到了纯度大于99.99%的La-Gd,纯度大于99.8%的Dy-Lu和含量高于65%的Tb_4O_2富集物。Tb的收率大于95%。串级总级数为38级。通过对P_(507)萃取实际体系中稀土元素行为的研究,建立了多元体系中稀土在两相分配的经验模型。Z=C_1H~(C2)×T~(C_3)e~(c_4X(Tb)+C_5X(Dy))和具有一定物理意义的半热力学半经验模型。YT=(Z/H)~3[Σ from i=1 to m of CiXi + Co]根据氨化P_(507)萃取工艺中稀土总浓度在两相的分布规律,提出了一种适合氨化P_(507)萃取分离多元混合稀土工艺的串级计算方法,并用FORTRAN语言编写 了计算程序。使用自编的计算程序进行了氨化P_(507)萃取分离Gd、Tb、Dy三出口工艺的串级模拟计算,计算结果与实验值基本一致。同时,对文献中报导的中间某级开设出口的一分三工艺也进行了串级计算,根据计算结果讨论了两种工艺的优缺点。对恒定混合萃取比的多元稀土萃取分离工艺,进行了在不同串级条件下分界元素在各级的积累及易萃组份和难萃取份的有效分离系数在各级变化规律的计算。结果表明,有效分离系数在级体中出现一极小值β~*,并且β~*值的大小与其出现在级体中的位置随条件不同而改变。对同一萃取体系,当出口产品较纯时,用线性回归分析法关联计算数据得到了β~*与出口产品组成和总萃取比的经验关系式,在萃取段有(A、B与C分离的工艺)β~*/β_B~C=C1+C2EM+C_3ln (A1)/(B1)引入有效分离系数后,进行了环烷酸萃取分离钇与镧系元素的串级模拟计算,计算结果与实验值基本吻合。
Resumo:
The oxovanadium phosphonates (VO(P-204)(2) and VO(P-507)(2)) activated by various alkylaluminums (AlR3, R = Et, i-Bu, n-Oct; HAIR(2), R = Et, i-Bu) were examined in butadiene (Bd) polymerization. Both VO(P-204)(2) and VO(P-507)(2) showed higher activity than those of classical vanadium-based catalysts (e.g. VOCl3, V(acac)(3)). Among the examined catalysts, the VO(P-204)(2)/Al(Oct)(3) system (I) revealed the highest catalytic activity, giving the poly(Bd) bearing M-n of 3.76 x 10(4) g/mol, and M-w/M-n ratio of 2.9, when the [Al]/[V] molar ratio was 4.0 at 40 degrees C. The polymerization rate for I is of the first order with respect to the concentration of monomer. High thermal stability of I was found, since a fairly good catalytic activity was achieved even at 70 degrees C (polymer yield > 33%); the M-n value and M-w/M-n, ratio were independent of polymerization temperature in the range of 40-70 degrees C. By IR and DSC, the poly(Bd)s obtained had high 1,2-unit content (> 65%) with atactic configuration. The 1,2-unit content of the polymers obtained by I was nearly unchanged, regardless of variation of reaction conditions, i.e. [Al]/[V], ageing time, and reaction temperature, indicating the high stability of stereospecificity of the active sites.
Resumo:
The catalyst system neodymium phosphonate Nd(P-507)(3)/H2O/Al(i-Bu)(3) for the polymerization of styrene was examined. Effects of the addition order of the catalyst components, catalyst aging time and aging temperature on the catalyst activity and the polymer characteristics were investigated. The catalyst activity for isospecific polymerization of styrene increases with aging time and reaches the maximum with a catalyst aged for 45 min at 70 degrees C. The aging time that the catalyst needs to reach the highest activity for isospecific polymerization decreases with increasing aging temperature. The preformed catalyst and the in situ catalyst were compared with respect to the kinetic behavior of the styrene polymerization and the polymer characteristics.
Resumo:
通过实验,研究了2-乙基已基膦酸单(2-乙基已基)酯,在盐酸介质中萃取铅的规律和机理,为荧光级稀土生产提供了理论依据。
Resumo:
本采用萃取色谱法,以P507萃淋树脂为固定相,以HCl-NH4Cl体系为淋洗液,研究了高纯Nd2O3(99.999%~99.9999%)中稀土杂质与Nd基体的分离方法。选择螯合剂-活性碳柱富集淋洗液中痕量稀土,采用火花源质谱法分析,测定下限0.01μg/g。
Resumo:
本文采用萃取色谱法以P507萃淋树脂为固定相,以HCl-NH4Cl体系为淋洗液,研究了高纯Er2O3(99.999%~99.9999%)中稀土杂质和Er基体的分离方法,并选择了富集方法和火花源质谱测定条件,达到了纯度为99.9999%的超纯Er2O3的分析要求。
Resumo:
本文采用萃取色谱法,以P507萃淋树脂为固定相,以HCl-NH4Cl体系为洗脱液,研究了99.999%~99.9999%高纯Gd2O3中稀土杂质和Gd基体的分离方法,并选择了富集方法和火花源质谱测定条件,达到了纯度为99.9999%的高纯Gd2O3的分析测定要求
Resumo:
研究了P_(507)从HNO_3体系和HCl体系萃取重稀土Er、Tm、Yb、Lu的规律。从HNO_3体系中萃取,不论是单一组份或者多元混合组份,很快达到平衡。但从HCl体系中萃取,平衡缓慢,萃取单一稀土时温度、水相稀土浓度和酸度对平衡时间都有明显影响,萃取多元混合稀土时即使是在稀土浓度较高而酸度较低的情况下萃取平衡亦是相当缓慢的。HCl体系中Cl增加对平衡时间无明显影响,而加入少量NO_3~-离子不论是单一或者多元混合稀土体系,萃取平衡时间大大缩短。
Resumo:
BACKGROUND: The value of adjuvant radiotherapy in triple negative breast cancer (TNBC) remains unclear. A systematic review and meta-analysis was conducted in TNBC patients to assess survival and recurrence outcomes associated with radiotherapy following either breast conserving therapy (BCT) or post-mastectomy radiotherapy (PMRT). METHODS: Four electronic databases were searched from January 2000 to November 2015 (PubMed, MEDLINE, EMBASE and Web of Science). Studies investigating overall survival and/or recurrence in TNBC patients according to radiotherapy administration were included. A random effects meta-analysis was conducted using mastectomy only patients as the reference. RESULTS: Twelve studies were included. The pooled hazard ratio (HR) for locoregional recurrence comparing BCT and PMRT to mastectomy only was 0.61 (95% confidence interval [CI] 0.41-0.90) and 0.62 (95% CI 0.44-0.86), respectively. Adjuvant radiotherapy was not significantly associated with distant recurrence. The pooled HR for overall survival comparing BCT and PMRT to mastectomy only was 0.57 (95% CI 0.36-0.88) and HR 1.12 (95% CI 0.75, 1.69). Comparing PMRT to mastectomy only, tests for interaction were not significant for stage (p=0.98) or age at diagnosis (p=0.85). However, overall survival was improved in patients with late-stage disease (T3-4, N2-3) pooled HR 0.53 (95% CI 0.32-0.86), and women <40 years, pooled HR 0.30 (95% CI 0.11-0.82). CONCLUSIONS: Adjuvant radiotherapy was associated with a significantly lower risk of locoregional recurrence in TNBC patients, irrespective of the type of surgery. While radiotherapy was not consistently associated with an overall survival gain, benefits may be obtained in women with late-stage disease and younger patients.