Concentration quenching in erbium-doped tellurite glasses

Er2O3-doped TeO2-ZnO-La2O3 modified tellurite glasses were prepared by the conventional melt-quenching method, and the Er3+ : I-4(13/2) -> I-4(15/2) fluorescence properties have been studied for different Er3+ concentrations. Infrared spectra were measured in order to estimate the exact content of OH- groups in samples. Based on the electric dipole-dipole interaction theory, the interaction parameter, C-Er,(Er), for the migration rate of Er3+ : I-4(13/2) -> I-4(13/2) in modified tellurite glass was calculated. Finally, the concentration quenching mechanism using a model based on energy transfer and quenching by hydroxyl (OH-) groups was presented. (c) 2005 Elsevier B.V. All rights reserved.

Analysis of steric mass-action model for protein adsorption equilibrium onto porous anion-exchange adsorbent

The ion-exchange equilibrium of bovine serum albumin (BSA) to an anion exchanger, DEAE Spherodex M, has been studied by batch adsorption experiments at pH values ranging from 5.26 to 7.6 and ionic strengths from 10 to 117.1 mmol/l. Using the unadjustable adsorption equilibrium parameters obtained from batch experiments, the applicability of the steric mass-action (SMA) model was analyzed for describing protein ion-exchange equilibrium in different buffer systems. The parametric sensitivity analysis was performed by perturbing each of the model parameters, while holding the rest constant. The simulation results showed that, at high salt concentrations or low pHs close to the isoelectric point of the protein, the precision of the model prediction decreased. Parametric sensitivity analysis showed that the characteristic charge and protein steric factor had the largest effects on ion-exchange equilibrium, while the effect of equilibrium constant was about 70%-95% smaller than those of characteristic charge and steric factor under all conditions investigated. The SMA model with the relationship between the adjusted characteristic charge and the salt concentration can well predict the protein adsorption isotherms in a wide pH range from 5.84 to 7.6. It is considered that the SMA model could be further improved by taking into account the effect of salt concentration on the intermolecular interactions of proteins. (c) 2006 Elsevier Ltd. All rights reserved.

果蝇 virilis section 的起源和系统发育研究

果蝇 virilis section(Hsu 1949)自建立以来其合理性在果蝇系统发育中还没有得到 检验。本文以线粒体烟酰胺腺嘌呤二核苷酸脱氢酶第二亚单位基因(ND2)全序列和细 胞色素氧化酶I 基因(COI)部分片段以及核中乙醇脱氢酶基因Adh 的编码区为遗传标 记，对virilis section 内61 个物种(13 个未发表新种),共计117 个个体进行了序列测 定。通过对单个基因和合并数据集进行简约分析，以及对合并数据集进行邻接法分析 和贝叶斯分析，本研究试图对以下问题进行探讨：(1)果蝇virilis section 的合理性。 (2)各种组间的系统关系。(3)种组内部各物种间的系统关系。(4)果蝇virilis section 的进化历史。现将主要结果总结如下： 1)分子系统学研究显示果蝇virilis section 为一个紧密相关的进化簇，为果蝇virilis section 的合理性从分子遗传学的角度提供了证据。 2)系统发育分析支持果蝇polychaeta 种组为单系群，该种组与未归类物种D. fluvialis 具有较近的亲缘关系。它们形成virilis section 中早期分化出的谱系。robusta 种组、melanica 种组、quadrisetata 种组以及新种组间关系较近。其中，robusta 种亚 组和melanica 种组关系较近；quadrisetata 种组和新种组形成姐妹群，它们形成的谱 系与robusta 种组内的okadai 种亚组关系紧密。 3) polychaeta 种组内部分为两枝，姐妹种D. polychaeta 和D. asper 组成其中一枝， 杂交实验显示它们具有非对称的交配前生殖隔离。另一枝中D. latifshahi 和D. daruma 显示了较近的亲缘关系。非洲物种D. hirtipes 与采自西双版纳的D. polychaeta X 关系 较近，提示它们可能有共同的起源。 4)合并数据集支持D. angor 种组为单系群，其中D. angor A 和D. velox 的姐妹种 关系得到较高的支持。但是该种组内部的其它物种间关系还需要进一步研究。 5) 分子系统发育分析结果清楚地表明robusta 种组属于多系发生。该种组被分为 三个种亚组：okadai 种亚组，robusta 种亚组和lacertosa 种亚组。在lacertosa 种亚组 内，D. bai 与其它成员相对远缘。okadai 种亚组的物种由于具有2n = 12 条染色体，且X 染色体为棒状，因而被认为是robusta 种组中较早分化出来的类群。但是我们的 分子数据并不支持这种观点。D. moriwakii 最初被描述为robusta 种组物种，后被订正 至melanica 种组。我们的系统发育分析显示该种与robusta 种亚组具有较近的关系， 而与melanica 种组物种的关系相对较远。除D. moriwakii 外，melanica 种组新旧大陆 物种各自形成单系。在系统树上，中国品系D. tsigana 与D. longiserrata 关系较近， 而与日本品系D. tsigana 的关系较远。杂交实验结果显示D. tsigana 中国品系和日本 品系间存在不对称的交配倾向，表明该种不同的地理群体间可能正处于分化阶段，而 中国品系则有可能已经演化为不同的物种。 6)果蝇quadrisetata 种组为单系发生，其内部分为两个明显的亚世系。第一个亚 世系包括D. sp T，D. barutani，D. potamophila 和D. spIZU；另一个亚世系包括D. beppui，D. karakasa，D. quadrisetata，D. multidentata，D. perlucida 和D. pilosa，其 中D. beppui 为该谱系中最早分化出的物种。 通过估计谱系间的分歧时间，本文推测果蝇virilis section 的祖先大约于中新世早 期起源于热带地区，virilis section 内许多物种可能栖息在旧大陆的低纬度地区，然后 通过适应性辐射扩散到各地。几乎所有的新大陆virilis section 物种是旧大陆物种通过 白令陆桥迁移到新大陆而演化形成的。

果蝇virillis section的起源和系统发育研究

果蝇vlfrlflisseetion（Hsu1949）自建立以来其合理性在果蝇系统发育中还没有得到检验。本文以线粒体烟酞胺腺嘌吟二核昔酸脱氢酶第二亚单位基因（ND2）全序列和细胞色素氧化酶I基因（COl）部分片段以及核中乙醇脱氢酶基因Adh的编码区为遗传标记，对viriltsseetion内61个物种（13个未发表新种），共计117个个体进行了序列测定。通过对单个基因和合并数据集进行简约分析，以及对合并数据集进行邻接法分析和贝叶斯分析，本研究试图对以下问题进行探讨：（1）果蝇virilisseetion的合理性。（2）各种组间的系统关系。（3）种组内部各物种间的系统关系。（4）果蝇virilissection的进化历史。现将主要结果总结如下：1）分子系统学研究显示果蝇virilissection为一个紧密相关的进化簇，为果蝇virilissection的合理性从分子遗传学的角度提供了证据。2）系统发育分析支持果蝇polychaeta种组为单系群，该种组与未归类物种D．Uvl'alis具有较近的亲缘关系。它们形成virilissection中早期分化出的谱系。robusta种组、melanica种组、quadrisetata种组以及新种组间关系较近。其中，robusta种亚组和melanica种组关系较近；quadrisetata种组和新种组形成姐妹群，它们形成的谱系与robusta种组内的。加dai种亚组关系紧密。3）polychaeta种组内部分为两枝，姐妹种D．polychaeta和D.asPer组成其中一枝，杂交实验显示它们具有非对称的交配前生殖隔离。另一枝中D.Iatshahi和D.daruma显示了较近的亲缘关系。非洲物种D．hirtiPes与采自西双版纳的D．polychaetaX关系较近，提示它们可能有共同的起源。4）合并数据集支持D．angor种组为单系群，其中D．angorA和D.velox的姐妹种关系得到较高的支持。但是该种组内部的其它物种间关系还需要进一步研究。5）分子系统发育分析结果清楚地表明robusta种组属于多系发生。该种组被分为三个种亚组：okadai种亚组，robsta种亚组和lacertosa种亚组。在laCertosa种亚组内，D.bai与其它成员相对远缘。okadai种亚组的物种由于具有2n=12条染色体，且X染色体为棒状，因而被认为是robusta种组中较早分化出来的类群。但是我们的分子数据并不支持这种观点。D.moriwakii最初被描述为robusta种组物种，后被订正至melanica种组。我们的系统发育分析显示该种与robsta种亚组具有较近的关系，而与melanica种组物种的关系相对较远。除D．moriwakii外，melanica种组新旧大陆物种各自形成单系。在系统树上，中国品系D．tsigana与D．longiserrata关系较近，而与日本品系D．tsigana的关系较远。杂交实验结果显示D．tsigana中国品系和日本品系间存在不对称的交配倾向，表明该种不同的地理群体间可能正处于分化阶段，而中国品系则有可能已经演化为不同的物种。6）果蝇quadrisetata种组为单系发生，其内部分为两个明显的亚世系。第一个亚世系包括；另，，个亚世系包括D．，其中D．beppui为该谱系中最早分化出韵物种。通过估计谱系间的分歧时间，本文推测果蝇virilissection的祖先大约于中新世早期起源于热带地区，virilissection内许多物种可能栖息在旧大陆的低纬度地区，然后通过适应性辐射扩散到各地。几乎所有的新大陆virilissection物种是旧大陆物种通过自令陆桥迁移到新大陆而演化形成的。

Near-infrared luminescent mesoporous MCM-41 materials covalently bonded with ternary thulium complexes

Two beta-diketones 4,4,4-trifluoro-1-2-thenoyl-1,3-butanedione (Htta) and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (Htfnb), which contain trifluoroalkyl chain, were selected as the main sensitizer for synthesizing Tm(L)(3)phen (L = tta, tfnb) complexes. The two near-infrared (NIR) luminescent thulium complexes have been covalently bonded to the ordered mesoporous material MCM-41 via a functionalized 1,10-phenanthroline (phen) group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (phen-Si) [The resultant mesoporous materials are denoted as Tm(L)(3)phen-MCM-41 (L = tta, tfnb)]. The Tm(L)(3)phen-MCM-41 (L = tta, tfnb) mesoporous materials were characterized by small-angle Xray diffraction (XRD) and N-2 adsorption/desorption, and they show characteristic mesoporous structure of MCM-41.

Novel proton exchange membranes based on water resistant sulfonated poly[bis(benzimidazobenzisoquinolinones)]

Novel water resistant sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBIs) were synthesized from 6,6'-disulfonic-4,4'-binaphthy]-1,1',8,8'-tetracarboxylic dianhydride (SBTDA) and various aromatic ether tetraamines. The resulting polymers with IEC in the range of 2.17-2.87 mequiv g(-1) have a combination of desired properties such as high solubility in common organic solvents, film-forming ability, and excellent thermal and mechanical properties. Flexible and tough membranes, obtained by casting from m-cresol solution, had tensile strength, elongation at break, and tensile modulus values in the range of 87.6-98.4 MPa, 35.8-52.8%, and 0.94-1.07 GPa. SPBIBI membranes with a high degree of sulfonation displayed high proton conductivity and a good resistance to water swelling as well. SPBIBI-b with IEC of 2.80 mequiv g(-1) displayed the conductivity of 1.74 x 10(-1) S cm(-1) at 100 degrees C, which was comparable to that of Nafion (R) 117 (1.78 x 10(-1) S cm(-1), at 100 degrees C).

Precipitates formed in a Mg-7Y-4Gd-0.5Zn-0.4Zr alloy during isothermal ageing at 250 degrees C

The ageing behavior of an extruded Mg-7Y-4Gd-0.5Zn-0.4Zr alloy during ageing at 250 degrees C has been investigated. Two types of phases have been observed during the ageing process. One is a lamellar phase with a 14H long periodic stacking structure, the other is the beta' phase with an ellipsoidal morphology. The increased mechanical properties of the peak-aged alloy are mainly ascribed to the presence of both of these phases at peak hardness.

Electronic structures of 5d transition metal monoxides by density functional theory

Bond distances, vibrational frequencies, electron affinities, ionization potentials, and dissociation energies of the diatomic 5d transition metal (except La) monoxides and their positively and negatively charged ions were studied by use of density functional methods B3LYP, BLYP, B3PW91, BPW91, B3P86, BP86, MPW1PW91, PBE1PBE, and SVWN. Our calculation shows that for each individual species, the calculated properties are quite sensitive to the method used. Compared with hybrid density functional method B3PW91 (B3P86), pure density functional method BPW91 (BP86) gives longer bond distance (lower vibrational frequency) from HfO to PtO for neutral species, HfO+ to IrO+ for cationic species, and HfO- to AuO- for anionic species. While for B3LYP and BLYP, the trend was observed for cationic species from HfO+ to IrO+ and anionic species from HfO- to AuO- (except TaO-), but not for neutrals. Pure density function methods BLYP, BPW91, and BP86 give larger dissociation energy compared with hybrid density functional methods B3LYP, B3PW91, and B3P86. SVWN in most cases gives the smallest bond distance, while BLYP gives the largest value. MPW1PW91 and PBE1PBE show the same performance in predicting the spectroscopic constants.

Energy transfer in phase-separated luminescent polymer films

The energy transfer in a blend film of poly 3-(2-(5-chlorobenzotriazolo) ethyl) thiophene (PCSET) and polyvinylcarzole (PVK) was investigated. The UV-VIS and photoluminescence (PL) results suggest that the energy transfer from PVK to PCBET leads to the enhancement of PL emission of PCBET. The AFM and LMF results indicated that the domains of blend polymer film are of micro-meter size. (C) 2001 Elsevier Science B.V. All rights reserved.

A new species of Bryodema (Orthoptera : Acridoidea) from China, with a key to the described species

A new species Bryodema nigrofrascia of the genus Bryodema Fieber, 1853 (Orthoptera, Acridoidea, Acrididae Oedipodinae) from China is described. A key to known species of the genus is given. The type specimens are deposited in the Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining, Qinghai.

A cell-centred finite volume method for modelling viscoelastic flow

An unstructured cell-centred finite volume method for modelling viscoelastic flow is presented. The method is applied to the flow through a planar channel and the 4:1 planar contraction for creeping flow of an Oldroyd-B fluid. The results are presented for a range of Weissenberg numbers. In the case of the planar channel results are compared with analytical solutions. For the 4:1 planar contraction benchmark problem the convection terms in the constitutive equations are approximated using both first and second order differencing schemes to compare the techniques and the effect of mesh refinement on the solution is investigated. This is the first time that a fully unstructured, cell-centredfinitevolume technique has been used to model the Oldroyd-B fluid for the test cases presented in this paper.

Technical Vocabulary and Medieval Text Types: A Semantic Field Approach

This paper seeks to discover in what sense we can classify vocabulary items as technical terms in the later medieval period. In order to arrive at a principled categorization of technicality, distribution is taken as a diagnostic factor: vocabulary shared across the widest range of text types may be assumed to be both prototypical for the semantic field, but also the most general and therefore least technical terms since lexical items derive at least part of their meaning from context, a wider range of contexts implying a wider range of senses. A further way of addressing the question of technicality is tested through the classification of the lexis into semantic hierarchies: in the terms of componential analysis, having more components of meaning puts a term lower in the semantic hierarchy and flags it as having a greater specificity of sense, and thus as more technical. The various text types are interrogated through comparison of the number of levels in their hierarchies and number of lexical items at each level within the hierarchies. Focusing on the vocabulary of a single semantic field, DRESS AND TEXTILES, this paper investigates how four medieval text types (wills, sumptuary laws, petitions, and romances) employ technical terminology in the establishment of the conventions of their genres.

Obesity markers and blood pressure in a sample of Portuguese children and adolescents.

Little information exists regarding the effect of several obesity markers on blood pressure (BP) levels in youth. Transverse study including 2494 boys and 2589 girls. Height, weight and waist were measured according to the international criteria and body fat (BF) by bioimpedance. BP was measured by an automated device. Hypertension was defined using sex-specific, age-specific and height-specific observation-points. Body mass index (BMI) and waist were positively related with systolic blood pressure (SBP) and diastolic blood pressure (DBP) and heart rate in both sexes, whereas the relationships with BF were less consistent. Stepwise linear regression analysis showed that BMI was positively related with SBP and DBP in both sexes, whereas BF was negatively related with SBP in both sexes and with heart rate in boys only; finally, waist was positively related with SBP in boys and heart rate in girls. Age and heart rate-adjusted values of SBP and DBP increased with BMI: for SBP, 117+/-1, 123+/-1 and 124+/-1 mmHg in normal, overweight and obese boys, respectively; corresponding values for girls were 111+/-1, 114+/-1 and 116+/-2 mmHg (mean+/-SE, P<0.001). Overweight and obese boys had an odds ratio for being hypertensive of 2.26 (95% confidence interval: 1.79-2.86) and 3.36 (2.32-4.87), respectively; corresponding values for girls were 1.58 (confidence interval 1.25-1.99) and 2.31 (1.53-3.50). BMI, not BF or waist, is consistently and independently related to BP levels in children; overweight and obesity considerably increase the risk of hypertension.