Secondary Bonding,C═H…O Hydrogen Bonding Assisted Supramolecular Associations and Charge Transfer (CT) Complexes of Organotelluriums and their Nonlinear Optical Properties

Abstract

A library of supramolecular assemblies of acyclic- and cyclic organotelluriums assisted by intermolecular Te… X (X = Cl, Br, I, O, S) secondary bonds has been synthesized and X-ray characterized. In each case the immediate coordination geometry around the central Te atom is pseudotrigonal bipyramidal in which two methylene carbon atoms (attached to Te) in cyclic organotelluriums and methyl carbon atoms in acyclic organotelluriums and the stereochemically active electron lone pair occupy equatorial positions whereas the axial positions are occupied by halogen, oxygen or sulphur. They exists either as (a) ordered oligomers (trimeric, tetrameric, octameric aggregates) (b) cross linked chains, (c) zig-zag ?2 dimensional ribbons and stairs, and (d) 3-dimensional supramolecular networks. It is observed that the supramolecular associations assisted by Te…O and Te…S secondary bonds are modified whereas those assisted by Te…halogen remain more or less the same vis-à-vis the supramolecular associations present in their precursors in the solid state. The first detection of C─H…O hydrogen bonds in organotellurium compounds has been done and their use in the synthesis of tellurium essential and ligand essential supramolecular assemblies is demonstrated. Tetraorganotelluroxanes obtained by easy and efficient routes represent the examples of cooperative participation of intermolecular and intramolecular Te…O secondary bonds and C─H…O hydrogen bonds. Hypervalent Te─I (formed through n → σ* orbital interactions) bonds in cyclic telluranes act as potential synthons for the formation of CT complexes possessing unusual structures. The utility of organotelluriums in the serendipitous synthesis of the first triphenyl methyl phosphonium salts of [C₄H₈TeI₄]^2? and [TeI₆]^2? anions is shown. The second harmonic generation (SHG) efficiency of some of these new supramolecular assemblies of organotelluriums indicates that the presence of C─H…O hydrogen bonds enhances their non linear optical (NLO) properties.     

Effects of Saignée and Bentonite Treatment on Phenolic Compounds of Marquette Red Wines

To improve the phenolic extraction and color stability of red wine made from cold-hardy grapes, two winemaking practices, saignée and bentonite, were applied separately and in combination on Marquette grapes at crushing. The effects of these winemaking strategies on Marquette wine’s basic chemical properties, monomeric and polymeric phenolic compounds were studied, as well as the development of color characteristics from crushing to 5 months of aging. The saignée (9% juice run-off) treatment showed little impact on the phenolic content of the finished wine, but showed an increase in color intensity. A hue shift towards an orange-yellow tone was observed in the bentonite-treated wines, which was associated with a loss of monomeric anthocyanins. The combination of saignée and bentonite showed less impact on removing anthocyanins and wine color, and increased phenolics content, therefore improving the extraction of non-anthocyanins monomeric phenolics. Although this combination treatment led to the highest concentration of tannin content after pressing, this difference between the control and other treatments disappeared over time. These results suggested that the interactions between tannins and other wine compounds still occur after removing proteins in Marquette wines.     

广西不同林龄马尾松人工林林下木本植物种间联结动态

为了解广西不同林龄马尾松(Pinus massoniana)人工林林下主要木本植物间相互作用的变化规律,以空间代替时间的方法,在群落调查的基础上采用多物种间的总体关联显著性检验、x²统计量分析和Spearman秩相关检验对广西不同林龄马尾松人工林亚乔木层和灌木层木本植物种群进行种间联结分析。结果表明：(1)不同林龄阶段亚乔木层物种间的总体关联性均呈不显著正联结,从中林龄到成熟林再到过熟林,灌木层物种间的总体关联性变化趋势为不显著负联结→不显著正联结→不显著正联结;(2)随着林龄的增长,林下主要木本植物正联结种对比例增加,种间关系逐渐趋于正联结,群落稳定性逐渐增加,向顶级群落方向演替;(3)马尾松人工林林下主要木本植物中大多数种对间的相关性并不显著,物种间的关系较为松散,种对间的关联性较弱,所研究的马尾松人工林仍处于不稳定的演替阶段。充分利用种间关系研究的结果对马尾松人工林群落进行科学维护,可以加速马尾松人工林群落的恢复。     

大针茅草原蛴螬群落主要种群空间分布特征研究

在围封状态下，对内蒙古典型草原主要群落类型——大针茅草原蛴螬群落主要种群的空间分布特征进行了研究．结果表明：蛴螬群落的最小积累采样面积约为2m^2。草原蛴螬的几个主要种群在其季节性密度高峰期，空间分布方式均表现为不同程度的聚集分布．从种群密度最高时的空间分布看，东方绢金龟、弓斑常丽金龟和黑皱鳃金龟聚集程度较高，马铃薯鳃金龟聚集程度较低．几种优势种问大多表现为正关联，而常见种和稀有种之间大都表现为负关联。     

蚕豆叶片几丁质酶的抗虫性研究

探讨了植物体内几丁质酶与昆虫种群动态的关系，发现几丁质醇对蚜虫的发育、存活和生殖都有明显的影响，并最终调节种群的动态。实验结果显示，几丁质酶对若蚜影响比成蚜大，并与蚜虫的翅型变化关系密切，表现了其作为抗性物质所具有的低御虫害的功能。     

“Found in Translation”: An Evolutionary Framework for Auditory–Visual Relationships

The development of computational artifacts to study cross-modal associations has been a growing research topic, as they allow new degrees of abstraction. In this context, we propose a novel approach to the computational exploration of relationships between music and abstract images, grounded by findings from cognitive sciences (emotion and perception). Due to the problem’s high-level nature, we rely on evolutionary programming techniques to evolve this audio–visual dialogue. To articulate the complexity of the problem, we develop a framework with four modules: (i) vocabulary set, (ii) music generator, (iii) image generator, and (iv) evolutionary engine. We test our approach by evolving a given music set to a corresponding set of images, steered by the expression of four emotions (angry, calm, happy, sad). Then, we perform preliminary user tests to evaluate if the user’s perception is consistent with the system’s expression. Results suggest an agreement between the user’s emotional perception of the music–image pairs and the system outcomes, favoring the integration of cognitive science knowledge. We also discuss the benefit of employing evolutionary strategies, such as genetic programming on multi-modal problems of a creative nature. Overall, this research contributes to a better understanding of the foundations of auditory–visual associations mediated by emotions and perception.     

Tough and fluorescent hydrogels composed of poly(hydroxyurethane) and poly(stearyl acrylate-co-acrylic acid) with hydrophobic associations and hydrogen bonds as the physical crosslinks

Fluorescent hydrogels have promising applications in biomedical and engineering fields. However, they are usually mechanically weak. Here, we report a fluorescent composite hydrogel with high toughness, which is facilely prepared by solution casting ethanol solution of poly(hydroxyurethane) (PHU) and poly(stearyl acrylate-co-acrylic acid) (P[SA-co-AAc]) followed by swelling the casted film in water. The composite hydrogels with water content of 62–78 wt% possess remarkable mechanical performances, with tensile breaking stress of 0.3–1.1 MPa, breaking strain of 280%–400%, Young's modulus of 0.2–0.7 MPa, and tearing fracture energy of 1250–2630 J/m². The high toughness is attributed to the effective energy dissipation of the network with hydrophobic association of SA units and hydrogen bonds between PHU and P(SA-co-AAc) as the physical crosslinks. The intense aggregation of carbamates and the formation of carbamate clusters through intra- and intermolecular hydrogen bonds endow the composite hydrogel with strong fluorescence. These hydrogels with high toughness and strong fluorescence should find applications in flexible electronics, information display, and biomedical devices.     

高温胁迫对植食性昆虫影响研究进展

昆虫作为变温动物类群,极易遭受高温胁迫的影响。研究高温胁迫对植食性昆虫的影响,可为气候变暖背景下农林害虫的种群动态监测及地理适生区预测提供重要理论依据。笔者从植食性昆虫个体、种间互作关系、种群及群落3个层面,综述了高温胁迫对植食性昆虫影响的国内外进展。研究发现,高温胁迫会对植食性昆虫个体的生长发育、繁殖及生理生化带来负面效应,但昆虫自身也会进化出一系列基于形态、行为及基因表达的热胁迫响应机制。高温胁迫对寄主植物、天敌、共生微生物的影响也能够通过种间互作传递给植食性昆虫,并导致寄主植物-植食性昆虫-天敌3级营养关系发生变化。同时,高温胁迫还能通过影响昆虫个体及种间关系,间接影响昆虫的种群动态、种群多样性及其生态功能,并可能导致植食性昆虫的种群大爆发或衰退。最后,笔者认为此领域未来研究方向为:在个体层面上,应优化高温胁迫处理方式并综合考虑干旱和降水等环境因子,开展农林害虫种群的长期野外监测,应注重高温胁迫对昆虫参与生长发育繁殖功能基因的影响;在种间关系层面上,应关注高温胁迫对昆虫关联的复杂多样的食物网及互作体系的影响;此外,应结合高温胁迫对不同昆虫种类自身生理特性和行为模式的影响,阐明温度升高对昆虫群落的影响。