Multiple garnet growth in garnet-kyanite-staurolite gneiss, Pangong metamorphic complex, Ladakh Himalaya: New constraints on tectonic setting

Garnet-kyanite-staurolite gneiss in the Pangong complex, Ladakh Himalaya, contains porphyroblastic euhedral garnets, blades of kyanite and resorbed staurolite surrounded by a fine-grained muscovite-biotite matrix associated with a leucogranite layer. Sillimanite is absent. The gneiss contains two generations of garnet in cores and rims that represent two stages of metamorphism. Garnet cores are extremely rich in Mn (X(Sps) = 0.35-038) and poor in Fe (X(Alm) = 0.40-0.45), whereas rims are relatively Mn-poor (X(Sps) =0.07-0.08), and rich in Fe (X(Alm), = 0.75-0.77). We suggest that garnet cores formed during prograde metamorphism in a subduction zone followed by abrupt exhumation, during early collision of the Ladakh arc and Karakoram block. The subsequent India-Asia continental collision subducted the metamorphic rocks to a mid-crustal level, where the garnet rims overgrew the Mn-rich cores at ca. 680 degrees C and ca. 8.5 kbar. PT calculations were estimated from phase diagrams calculated using a calculated bulk chemical composition in the Mn-NCKFMASHT system for the garnet-kyanite-staurolite-bearing assemblage. Muscovites from the metamorphic rocks and associated leucogranites have consistent K-Ar ages (ca. 10 Ma), closely related to activation of the Karakoram fault in the Pangong metamorphic complex. These ages indicate the contemporaneity of the exhumation of the metamorphic rocks and the cooling of the leucogranites. (C) 2011 Elsevier B.V. All rights reserved.

ORTHOPYROXENE plus SILLIMANITE PREDATING SAPPHIRINE plus QUARTZ: A RARE CASE OF ULTRAHIGH-TEMPERATURE METAMORPHISM FROM THE CENTRAL ZONE, LIMPOPO COMPLEX, SOUTH AFRICA

Sapphirine + quartz and orthopyroxene + sillimanite occur in garnet from an Mg-Al granulite from the Central Zone of the Limpopo Complex in South Africa. Textural evidence and a chemical gradient in garnet between the zones preserving the inclusions argue for the formation of sapphirine + quartz after orthopyroxene + sillimanite. Petrological observations, pressure-temperature phase diagrams, and compositional and model proportion results on isopleths indicate the sapphirine + quartz + garnet + orthopyroxene (high-Al) assemblage as the peak metamorphic assemblage (similar to 1050 degrees C at similar to 8.5 kbars), whereas orthopyroxene (low-Al) + sillimanite represents the prograde stage (at ca. 900 degrees C at similar to 8.5 kbars). Our report of these two diagnostic ultrahigh-temperature mineral assemblages in garnet from an Mg-Al granulite is unique, given the rare occurrence of sapphirine + quartz postdating orthopyroxene + sillimanite assemblage in granulites.

The key role of polymer grafted nanoparticles in the phase miscibility of an LCST mixture

Blends of bromo-terminated polystyrene (PS-Br) and poly(vinyl methylether) (PVME) exhibit lower critical solution temperatures. In this study, PS-Br was designed by atom transfer radical polymerization and was converted to thiol-capped polystyrene (PS-SH) by reacting with thiourea. The silver nanoparticles (nAg) were then decorated with covalently bound PS-SH macromolecules to improve the phase miscibility in the PS-Br-PVME blends. Thermally induced demixing in this model blend was followed in the presence of polystyrene immobilized silver nanoparticles (PS-g-nAg). The graft density of the PS macromolecules was estimated to be ca. 0.78 chains per nm(2). Although the matrix and the grafted molecular weights were similar, PS-g-nAg particles were expelled from the PS phase and were localized in the PVME phase of the blends. This was addressed with respect to intermediate graft density and favourable PS-PVME contacts from microscopic interactions point of view. Interestingly, blends with 0.5 wt% PS-g-nAg delayed the spinodal decomposition temperature in the blends by ca. 18 degrees C with respect to the control blends. The scale of cooperativity, as determined by differential scanning calorimetry, increased only marginally in the case of PS-g-nAg; however, it increased significantly in the presence of bare nAg particles.

A Comparative Study of Early Afterdepolarization-Mediated Fibrillation in Two Mathematical Models for Human Ventricular Cells

Early afterdepolarizations (EADs), which are abnormal oscillations of the membrane potential at the plateau phase of an action potential, are implicated in the development of cardiac arrhythmias like Torsade de Pointes. We carry out extensive numerical simulations of the TP06 and ORd mathematical models for human ventricular cells with EADs. We investigate the different regimes in both these models, namely, the parameter regimes where they exhibit (1) a normal action potential (AP) with no EADs, (2) an AP with EADs, and (3) an AP with EADs that does not go back to the resting potential. We also study the dependence of EADs on the rate of at which we pace a cell, with the specific goal of elucidating EADs that are induced by slow or fast rate pacing. In our simulations in two-and three-dimensional domains, in the presence of EADs, we find the following wave types: (A) waves driven by the fast sodium current and the L-type calcium current (Na-Ca-mediated waves); (B) waves driven only by the L-type calcium current (Ca-mediated waves); (C) phase waves, which are pseudo-travelling waves. Furthermore, we compare the wave patterns of the various wave-types (Na-Ca-mediated, Ca-mediated, and phase waves) in both these models. We find that the two models produce qualitatively similar results in terms of exhibiting Na-Ca-mediated wave patterns that are more chaotic than those for the Ca-mediated and phase waves. However, there are quantitative differences in the wave patterns of each wave type. The Na-Ca-mediated waves in the ORd model show short-lived spirals but the TP06 model does not. The TP06 model supports more Ca-mediated spirals than those in the ORd model, and the TP06 model exhibits more phase-wave patterns than does the ORd model.

Na2.44Mn1.79(SO4)(3): a new member of the alluaudite family of insertion compounds for sodium ion batteries

Sodium-ion batteries have been extensively pursued as economic alternatives to lithium-ion batteries. Investigating the polyanion chemistry, alluaudite structured Na2Fe2II(SO4)(3) has been recently discovered as a 3.8 V positive electrode material (Barpanda et al., Nature Commun., 5: 4358, 2014). Registering the highest ever Fe-III/Fe-II redox potential (vs. Na/Na+) and formidable energy density, it has opened up a new polyanion family for sodium batteries. Exploring the alluaudite family, here we report isotypical Na2+2xMn2-xII(SO4)(3) (x = 0.22) as a novel high-voltage cathode material for the first time. Following low-temperature (ca. 350 degrees C) solid-state synthesis, the structure of this new alluaudite compound has been solved adopting a monoclinic framework (s.g. C2/c) showing antiferromagnetic ordering at 3.4 K. Synergising experimental and ab initio DFT investigation, Na2+2xMn2-xII(SO4)(3) has been found to be a potential high-voltage (ca. 4.4 V) cathode material for sodium batteries.

Polibio, el mundo helenístico y la problemática cultural : algunas líneas de reflexión en los últimos veinte a��os

Resumen: Nuestro conocimiento de algunos aspectos de las Historias de Polibio se ha incrementado significativamente durante las dos últimas décadas. En ese sentido, ha habido ciertos desarrollos importantes con respecto a aspectos culturales de la obra, cuyo alcance ha ido permitiendo repensar durante estos a��os algunos presupuestos clásicos sobre la relación entre Polibio, Roma y el mundo helenístico. Proponemos aquí ofrecer un rápido análisis de las tres principales líneas de estudio propuestas por los estudiosos, cuyo alcance es considerado, en efecto, como un total reubicación del historiador aqueo al interior del universo cultural del mundo helenístico.

Aristophanis comoediae undecim, graece et latine : ad fidem optimorum Codicum MSS. emendatae cum nova octo comoediarum interpretatione latina, e notis ad fingulas ineditis Stephani Bergleri, nec non Caroli Andreae Dukeri ad quatuor priores, accedunt deperditarum comoediarum fragmenta a Theod. Cantero et Gul. Coddaeo collecta, earumque indices a Joh. Meursio & Joh. Alb. Fabricio digefti, curante Petro Burmanno Secundo, qui praefationem praefixit

Aristófanes nasceu em Atenas entre 450 e 445 a.C. e morreu por volta de 388 a.C. Considerado o principal representante da comédia antiga, em suas peças predominavam a sátira política e a social. Suas primeiras comédias foram assinadas sob pseudônimo e somente após ‘Os Acarnianos’ (ou ‘Acarnanos’) tornou-se conhecido. Da sua obra apenas onze peças conservaram-se integralmente. Esta coleção, em dois volumes, contém onze peças. O primeiro volume inclui ‘Os Plutos’ (publicada no ano de 388 a.C.), sua ultima comédia; ‘As Nuvens’ (423 a.C.); ‘As Rãs’ (405 a.C.); ‘Os Cavaleiros’ (424 a.C.); ‘Os Acarnianos’ (425 a.C.) e ‘As Vespas’ (422 a.C.). O segundo volume contém ‘Os Pássaros’ (414 a.C.); ‘A Paz’(421a.C.); ‘A Assembleia das mulheres’ (392 a.C.); ‘As Convocadas’ (411 a.C.) e ‘Lisistrata��� (411 a.C.)

拟南芥有性生殖模式和叶片特性对大气CO2浓度变化的响应

预计到本世纪末，大气CO2浓度将会增加到540～970ppm，大气CO2浓度升高所引起的全球气候变化已经受到广泛的关注。植物生长依赖CO2，并且对大气CO2浓度升高在结构和生理上产生响应。目前已有大量报道，从生态系统、群落、种群、个体、器官、组织、生理以及生化等水平上研究高浓度CO2所对植物产生的影响。但是有关高浓度CO2对植物有性生殖影响的报道却很少，同时多数实验均建立在短期的生殖响应，忽视了植物在长期高CO2浓度下具有的反馈作用和CO2浓度变化对植物的驯化作用。植物有性生殖与其生态适应性和农作物籽粒产量的关系极为密切;同时，植物有性生殖特性的变化，也可作为预测植物对全球气候变化响应的重要指标之一。为此，利用高浓度CO2对植物进行长期选择实验将很有必要。研究结果将为预测未来大气CO2浓度增加的条件下陆地生态系统的演变趋势、全球变化对植物有性生殖响应的方式和机制提供新的思路和有效方法。 　　在本研究中，我们以模式植物拟南芥(Arabidopsis thaliana)作为实验材料，利用370和700ppm CO2对其进行连续8个世代处理，首先研究高浓度CO2对每一个世代的拟南芥有性生殖特性的影响，然后比较各个世代中各种生殖特性指标变化的规律，从细胞、组织和个体尺度上揭示拟南芥有性生殖对全球变化的响应模式。此外，在700ppm CO2处理下，我们对拟南芥叶片生理、生化以及结构的变化进行了相关研究。两部分研究结果及主要结论如下： 　　首先，在每一个世代中，与370ppm CO2相比较，700ppm CO2处理显著促进了拟南芥开花，缩短生长周期，增加花、角果及种子等生殖的产量，降低种子N含量，提高种子C/N比、种子千粒重以及生殖生物量所占总生物量的比例等，而对种子萌发率、角果所含种子数目以及角果长度则无显著影响。但是， 通过对相同CO2浓度处理条件下，不同世代之间的研究结果比较发现，不同世代之间相关的生殖生物学指标并无显著差异。 　　其次，高浓度CO2显著降低叶片气孔密度、气孔指数、气孔导度以及蒸腾速率。在高浓度CO2处理下，叶肉细胞中叶绿体数目、叶绿体宽度和表观面积、淀粉粒大小和数量、叶片和细胞壁厚度等都显著增加，但是基粒内囊体膜的数量却显著下降。叶片中碳水化合物如可溶性总糖、淀粉以及纤维素含量在高浓度CO2下分别显著增加71.9%、78.7% 和 22.3%。此外，在高浓度CO2处理下，叶片中多数激素如如吲哚乙酸(indole-3-acetic acid, IAA)、赤霉素(gibberellin, GA)、玉米素核苷(zeatin riboside, ZR)、二氢玉米素核苷(dihydrozeatin riboside, DHZR)和异戊烯基腺苷(isopentenyl adenosine, iPA)均都显著地增加，而脱落酸(abscisic acid, ABA)含量却有所下降。最后，叶片中各种矿物质元素含量如N、P、K、Ca���Mg等含量在高浓度CO2处理下也都显著下降，而C/N比增加24.8％。 　　以上结果表明： 　　(1) 在每一个世代中，700ppm CO2处理对拟南芥各种有性生殖特性具有显著的影响，但是高浓度CO2处理对植物所引起的效应在多个世代以内并不能够传递给后代，所以在多个有性生殖世代内，高浓度CO2处理对植物生长、生殖没有驯化作用。 　　(2) 在高浓度CO2处理下，拟南芥叶片中叶绿体超微结构的变化，可能主要是由于叶绿体中淀粉粒数量和体积大小显著增加而引起。 　　(3) 在高浓度CO2处理下，由于拟南芥叶片内与促进细胞分裂与伸长的激素含量显著增加，从而对拟南芥植株生长发育速率的提高起了重要的作用。 　　(4) 拟南芥生长在高浓度CO2条件下，其叶片中各种矿质元素含量（如N、P、K、Ca���Mg）均显著降低，究其原因可能是，第一由于叶片中碳水化合物含量的显著增加而对矿物质元素具有稀释作用;第二由于蒸腾速率下降，引起矿质元素从根部随着蒸腾流运输到地上部分的含量相应减少。 　　

Taxonomic study of coenocytic green algae commonly growing on the coast of Karachi

Twelve commonly occurring coenocytic and siphonaceous species of marine benthic algae, i.e., Bryopsis pennatta Lamouroux, Caulerpa chemnitzia (Esper) Lamouroux, Ca. faridii Nizamuddin, Ca. manorensis Nizamuddin, Ca. racemosa (Forsskal) J. Agardh, Ca. taxifolia. (Vahl) C. Agardh, Chaetomorpha antennina (Bory de Saint-Vincent) Kutzing, Cladophora uncinella Harvey, Codium decorticatum (Woodward) Howe, Co. flabellatum Nizamuddin, Co. iyengarii Borgesen, and Valoniopsis pachynema (Martens) Borgesen, belonging to four different orders of the class Bryopsidophyceae, division Chlorophyta, were collected from the intertidal region of different coastal areas near Karachi (Pakistan) and investigated taxonomically. Codium decorticatum is a new report from this region and Co. decorticatum, Co. flabellatum and Co. iyengarii are described for the first time from the coast of Pakistan.

An investigation of the kinetics of CO2 uptake by a synthetic calcium based sorbent

This study examines the kinetics of carbonation by CO2 at temperatures of ca. 750 °C of a synthetic sorbent composed of 15 wt% mayenite (Ca12Al14O33) and CaO, designated HA-85-850, and draws comparisons with the carbonation of a calcined limestone. In-situ XRD has verified the inertness of mayenite, which neither interacts with the active CaO nor does it significantly alter the CaO carbonation–calcination equilibrium. An overlapping grain model was developed to predict the rate and extent of carbonation of HA-85-850 and limestone. In the model, the initial microstructure of the sorbent was defined by a discretised grain size distribution, assuming spherical grains. The initial input to the model – the size distribution of grains – was a fitted parameter, which was in good agreement with measurements made with mercury porosimetry and by the analysis of SEM images of sectioned particles. It was found that the randomly overlapping spherical grain assumption offered great simplicity to the model, despite its approximation to the actual porous structure within a particle. The model was able to predict the performance of the materials well and, particularly, was able to account for changes in rate and extent of reaction as the structure evolved after various numbers of cycles of calcination and carbonation.

Synthesis, characterization, and self-assembly of protein lysozyme monolayer-stabilized gold nanoparticles

Lysozyme monolayer-protected gold nanoparticles (Au NPs) which are hydrophilic and biocompatible and show excellent colloidal stability at low temperature, ca. 4 degrees C, were synthesized in aqueous medium by chemical reduction of HAuCl4 with NaBH4 in the presence of a familiar small enzyme, lysozyme. UV-vis spectra, transmission electron microscopy (TEM), atomic force microscopy, and X-ray photoelectron spectroscopy characterization of the as prepared nanoparticles revealed the formation of well-dispersed An NPs of ca. 2 nm diameter. Moreover, the color change of the An NP solution as well as UV-vis spectroscopy and TEM measurements have also demonstrated the occurrence of Ostwald ripening of the nanoparticles at low temperature. Further characterization with Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering indicated the formation of a monolayer of lysozyme molecules on the particle surface. FTIR data also indicated the intactness of the protein molecules coated on An NPs. All the characterization results showed that the monodisperse An NPs are well-coated directly with lysozyme. Driven by the dipole-dipole attraction, the protein-stabilized Au NPs self-assembled into network structures and nanowires upon aging under ambient temperature.

Well defined carbazole-based hole-transporting amorphous molecular materials

Monodisperse carbazole-based oligomers have been synthesized via C-N bonds formation by the modified Ullmann reaction. The full characterization of their structure is presented. These derivatives are highly thermally stable amorphous compounds with glass transition temperatures of 167-171 degrees C and thermal decomposition temperatures of ca. 400 degrees C. Amorphous films of the materials were fabricated and their hole-transporting properties were tested in a light emitting device with Alq(3) as an electroluminescent and electron-transporting material.

Calculation of chemical bond parameters in La1-xCaxCrO3 (0.0 <= x <= 0.3)

The chemical bond parameters, that is, bond covalency, bond susceptibility, and macroscopic linear susceptibility of La1-xCaxCrO3 (x = 0.0, 0.1, 0.2, 0.3) has been calculated using a semiempirical method. This method is the generalization of the dielectric description theory proposed by Phillips, Van Vechten, Levine, and Tanaka (PVLT). In the calculation of bond valence, two schemes were adopted. One is the bond valence sums (BVS) scheme, and the other is the equal-valence scheme. Both schemes suggest that for the title compounds bond covalency and bond susceptibility are mainly influenced by bond valence and are insensitive to the Ca doping level or structural change. Larger bond valences usually result in higher bond covalency and bond susceptibility. The macroscopic linear susceptibility increases (only slightly for BVS scheme) with the increasing Ca doping level. (C) 1999 John Wiley & Sons, Inc.

电感耦合等离子体光谱和质谱法分析贻贝标准物质

采用电感耦合等离子体光谱和质谱法分析了贻贝标准物质,光谱法测定K、Na���ca���Mg、P、Al、Fe、Zn、Nn和Sr,质谱法测定As、B、Cd、Co、Cr、Cu、Ca���Ce、Mn、Mo、Ni、Pb、Se、Sr、U和V。在优化的工作条件下,测定了来自基体元素K、Na���Ca���P、Cl和C���多原子离子~(39)K~(16)O、~(39)K_2、~(40)Ar~(23)Na���~(43)Ca~(16)O、~(42)Ca~(16)O、~(44)Ca~(16)O、~(31)P~(16)O_2、~(40)Ar~(37)Cl、~(35)Cl~(16)O、~(37)Cl~(16)O和~(40)Ar~(12)C���~(55)Mn、~(78)Se、~(63)Cu、~(59)Co、~(58)Ni、~(60)Ni、~(75)As、~(77)Se、~(51)V、~(53)Cr和~(52)Cr的干扰系数以及HNO_3+H_2O_2(3+2)、HNO_3+HClO_4(3+0.5)和HNO_3+H_2SO_4(3+0.5)等3种样品消解方法在一些生物重要元素的同位素处产生的表观浓度。光谱法的检出限0.001～0.75mg/L;质谱法的检出限0....

新的水溶性~(13)C NMR弛豫试剂的性质研究

合成了Gd~(3+)与2,3-二羟基-对-二甲苯胺四乙酸(DPTA)的固体配合物,研究了该化合物作为水溶性~(13)NMR弛豫试剂的性质,证明该试剂对增强各种氨基酸(苏氨酸、半胱氨酸、精氨酸、组氨酸、色氨酸和抗坏血酸)季碳原子的谱峰强度是十分有效的。精氨酸的自旋-晶格弛豫时间(T_1)测量表明,Gd-DPTA���使精氨酸分子中季碳T_1缩短200倍以上,效果优于Gd-DTPA���