996 resultados para 507.2


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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.

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为了改变稀土萃取工艺单靠人工模拟实验确定的落后状况和满足生产自动化的需要,近十多年来,国内外许多国家相继开展了稀土萃取数学模型的研究。但大部分工作侧重于两相平衡分配模型方面,所提出的相平衡分配模型中,用来进行串级计算的尚不多见,进行串级计算的也大多采取逐级计算法。对于P_(507)的萃取体系的数学模型的研究及用矩阵法进行串级模拟计算,国外尚未见报导。本论文在单级实验的基础上,对15个单一稀土的RECl_3-HCl-P_(507)体系及部分二元稀土的RECl_3-HCl-P_(507)和Re(NO_3)_3-HNO_3-P_(507)体系进行了萃取平衡的讨论,求出了上述体系中,单个稀土的表现浓度平衡常数;为了串级模拟计算的需要,提出了一个形式简单、较为通用的相平衡模型,用FORTRAN语言编写了该模型的回归程序,通过回归上述体系的单级实验数据,得到了各模型的系数。进行了(Sm-Gd)(NO_3)_3-HNO_3-P_(507)体系的分馏萃取实验,和中科院化工冶金所协作,对该体系的串级模拟计算进行研究。所用串级模型把两相稀土浓度、酸度、萃取剂浓度作为变量,由以上的相平衡模型和各级稀土、酸、萃取剂的物料稀算式构成的大型非线性方程组,采用改进牛顿法求解该方程组进行计算,用FORTRAN语言编写了计算程序,计算结果和实验结果较为一致。在此基础上,独立地继续进行研究,对串级模型进行了很大的改动,改进后的串级模型把酸度、萃取剂浓度这些变量隐含在相平衡模型中,去掉了原来串级模型的酸、萃取剂的物料稀算式。和原来串级模型相比,所含的变量及方程数均减少了2N个,大大减少了占用计算机的存贮单元,提高计算收敛速度。对计算方法作了扩大迭代方向,导找最优松弛因子,采用更为合理的保证解的笔挺理意义的限制等改进,使解的收敛稳定性得到了改善。根据以上的改进用FORTRAN语言编写了新的计算程序,计算结果和实验结果吻合很好,在拟合精度,迭代次数各方面都比用原来串级模型要好得多。此外,进行了改变串级条件的模拟计算,所得结果符合萃取规律的变化。对(Ho-Er)(NO_3)_3-HNO_3-P(507)进行了2个不同工艺条件的分馏萃取实验,模拟计算值和实验值相当吻合,该体系的改变工艺条件的计算,也得到了与萃取变化规律一致的计算结果。对于文献报导的P_(204)萃取体系的分馏萃取,也同样进行了模拟计算,计算值和实验值的吻合程度也相当令人满意。通过以上不同串级体系的模拟计算,说明了所提出的相平衡模型适用于串级模拟计算;秘诀进后的串级模型及计算方法更为可靠;证明了计算机辅助实验及工艺设计的可能性。为达到这个目标打下了基础。对环烷酸分离钇的萃取体系进行了合成料及龙南稀土料的分馏萃取实验,取得了出口水相钇的纯度>97%,有机相出口非钇稀土的纯度>94%的结果。根据该体系的实际情况,简化了串级模型,提出了一种处理多元稀土体系的模拟计算方法,用FORTRAN语言编写了逐级计算程序,计算结果和实验结果有一致的趋势,但具体数值差别较大,说明该简化的串级模型及计算方法均有不够完善之处,有待深入研究。提出了一种新的萃取方式,它具有三个物料出口,可同时把若干个稀土元素分成难、中、萃三组,经试探实验初步肯定了该萃取方式的实用性。若能将之用于工厂生产上,将会带来很大的经济效益,故值得进一步研究和推广应用。

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为探讨含水层介质对氯酚类污染物的吸附规律,以吉林市含水层介质--砂土为实验材料,采用批量吸附实验方法分别研究了2,4-二氯酚、2,4,6-三氯酚及五氯酚单独存在和共存条件下在砂土上的吸附-解吸行为,并对pH、离子强度对吸附过程的影响进行了探讨。结果表明,砂土对三种氯酚的吸附-解吸符合Freundlieh等温模型,吸附常数Kd分别为5.659、2.507和2.104,解吸常数分别为22.642、8.222和4.488;吸附反应符合二级吸附速率动力学方程,吸附速率常数K分别为0.4851kg·mg-1·h-1、0.0299kg·mg-1·h-1和0.1225kg·mg-1·h-1。氯酚在砂土上的吸附机理以疏水分配和配位体交换为主。在实验范围值内,吸附量随pH增加而减小,增加离子强度可以明显加强氯酚在砂土上的吸附.

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El presente artículo busca responder hasta qué punto pensar y participar en espacios de discusión acerca de la política de ciencia y tecnología permite resolver las tensiones propias de la interrelación de actores de la política de ciencia y tecnología, así como también legitimar la acción y decisión de la entidad llamada a diseñar la política científico-tecnológica. Con el acento puesto en las dos primeras décadas de funcionamiento de Colciencias, se concluye que la participación de los policy makers de esta entidad en las discusiones de ciencia y tecnología, así como la preocupación por pensar la ciencia y la tecnología en el entorno del modelo de desarrollo imperante en el momento, permitió una mayor consistencia y coherencia entre instrumentos y políticas y un diálogo legítimo con otras entidades y actores que por su naturaleza también implementaban políticas que afectaban a la ciencia y la tecnología.

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Mejillonesite, ideally NaMg(2)(PO(3)OH)(PO(4))(OH)center dot H(5)O(2), is a new mineral approved by the CNMNC (IMA 2010-068). It occurs as isolated crystal aggregates in thin zones in fine-grained opal-zeolite aggregate on the north slope of Cerro Mejillones, Antofagasta, Chile. Closely associated minerals are bobierrite, opal, clinoptilolite-Na, clinoptilolite-K, and gypsum. Mejillonesite forms orthorhombic, prismatic, and elongated thick tabular crystals up to 6 mm long, usually intergrown in radiating aggregates. The dominant form is pinacoid {100}. Prisms {hk0}, {h0l}, and {0kl} are also observed. The crystals are colorless, their streak is white, and the luster is vitreous. The mineral is transparent. It is non-fluorescent under ultraviolet light. Mohs' hardness is 4, tenacity is brittle. Cleavage is perfect on {100}, good on {010} and {001}, and fracture is stepped. The measured density is 2.36(1) g/cm(3); the calculated density is 2.367 g/cm(3). Mejillonesite is biaxial (-), alpha= 1.507(2), beta= 1.531(2), gamma= 1.531(2), 2V(meas) = 15(10)degrees, 2V(calc) = 0 degrees (589 nm). Orientation is X= a, Z= elongation direction. The mineral is non-pleochroic. Dispersion is r> v, medium. The IR spectrum contains characteristic bands of the Zundel cation (H(5)O(2)(+), or H(+)center dot 2H(2)O) and the groups P-OH and OH(-). The chemical composition is (by EDS, H(2)O by the Alimarin method, wt%): Na(2)O 9.19, MgO 26.82, P(2)O(5) 46.87, H(2)O 19, total 101.88. The empirical formula, based on 11 oxygen atoms, is Na(0.93)Mg(2.08)(PO(3)OH)(1.00) (PO(4)) (OH)(0.86) .0.95H(5)O(2) The strongest eight X-ray powder-diffraction lines [d in angstrom(I)(hkl)] are: 8.095(100)(200), 6.846(9) (210), 6.470(8)(111), 3.317(5)(302), 2.959(5)(132), 2.706(12)(113), 2.157(19)(333), and 2.153(9) (622). The crystal structure was solved on a single crystal (R = 0.055) and gave the following data: orthorhombic, Pbca, a = 16.295(1), b = 13.009(2), c = 8.434(1) angstrom, V= 1787.9(4) angstrom(3), Z = 8. The crystal structure of mejillonesite is based on a sheet (parallel to the b-c plane) formed by two types of MgO(6) octahedra, isolated tetrahedra PO(4) and PO(3)OH whose apical vertices have different orientation with respect to the sheet. The sheets are connected by interlayer, 5-coordinated sodium ions, proton hydration complexes, and hydroxyl groups. The structure of mejillonesite is related to that of angarfite, NaFe(5)(3+)(PO(4))(4)(OH)(4).4H(2)O and bakhchisaraitsevite, Na(2)Mg(5)(PO(4))(4)center dot 7H(2)O.

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This report examines recent updates to the regulation and enforcement of intellectual property (IP) rights in Korea and China, in particular patent rights including invention, utility, and design rights. This paper also discusses some features and issues of the actual IP enforcement situation in those countries in comparison with Japan.

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Using panel data of 57 countries during the period of 1995-2012, this study investigates the impact of intellectual property rights (IPR) processes on productivity growth. The IPR processes are decomposed into three stages, innovation process, commercialization process, and IPR protection process. Our results suggest that better IPR protection is directly associated with productivity improvement only in developed economies. In addition, the contribution of IPR processes on growth through foreign direct investment (FDI) appears to be very limited. Only FDI inflows in developed countries which help to create a better innovative capability lead to a higher growth. And in connection with FDI outflows, only IPR protection and commercialization processes are proven to improve productivity in the case of developing countries, particularly when the country acts as the investing country.