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Université de Fribourg

Hydrogen bond stabilization in Diels–Alder transition states: The cycloaddition of hydroxy-ortho-quinodimethane with fumaric acid and dimethylfumarate

Tamilmani, Venkatachalam ; Daul, Claude A. ; Lage Robles, Jaime ; Bochet, Christian G. ; Venuvanalingam, P.

In: Chemical Physics Letters, 2005, vol. 406, no. 4, p. 355-359

DFT investigations on the mechanism of Diels–Alder reactions of a hydroxy-ortho-quinodimethane with fumaric acid derivatives were performed to understand the origin of the syn or anti configuration of the adducts. The diene hydroxyl group and the dieneophile carboxyl group show hydrogen bonding in the transition state, significantly favouring the syn product. This reaction is poorly...

Université de Fribourg

Electrostatic control on endo/exo selectivity in ionic cycloaddition

Tamilmani, Venkatachalam ; Daul, Claude A. ; Venuvanalingam, P.

In: Chemical Physics Letters, 2005, vol. 416(4-6), p. 354

DFT method has been used in combination with various basis sets to model the ionic cycloaddition of cationic heteroaromatic diene, 2,3-dimethylisoquinoliniuim ion with cyclopentadiene with a view to understand the factors that influence the stereochemical outcome of the reaction. Calculations show that this reaction is an inverse electron demand type reaction and it passes through highly...

Université de Fribourg

Possible ring structures of armchair single-walled carbon nanotubes

Tamilmani, Venkatachalam ; Daul, Claude A. ; Jenny, Titus A.

In: Chimia, 2006, vol. 60, no. 4, p. 228-230

Energetics and the electronic structure of various types of single-walled carbon nanotubes have been investigated by using Density Functional Theory. Armchair [n,n], zigzag [n,0] and chiral [n,m] C₄₀H₂₀ nanotubes have been considered. Calculations show that the armchair isomer is the most stable among the three types and they further reveal the factors that stabilize this isomer....

Université de Fribourg

Facile and rapid formation of giant vesicles from glass beads

Tanasescu, Radu ; Mettal, Ute ; Colom, Adai ; Roux, Aurélien ; Zumbuehl, Andreas

In: Polymers, 2018, vol. 10, no. 1, p. 54

Giant vesicles (GVs) are widely-used model systems for biological membranes. The formulation of these vesicles, however, can be problematic and artifacts, such as degraded molecules or left-over oil, may be present in the final liposomes. The rapid formulation of a high number of artifact-free vesicles of uniform size using standard laboratory equipment is, therefore, highly desirable. Here,...

Université de Fribourg

Vesicle origami and the influence of cholesterol on lipid packing

Tanasescu, Radu ; Lanz, Martin A. ; Mueller, Dennis ; Tassler, Stephanie ; Ishikawa, Takashi ; Brezesinski, Renate Reiter∥⊥, Gerald ; Zumbuehl, Andreas

In: Langmuir, 2016, vol. 32, no. 19, p. 4896–4903

The artificial phospholipid Pad-PC-Pad was analyzed in 2D (monolayers at the air/water interface) and 3D (aqueous lipid dispersions) systems. In the gel phase, the two leaflets of a Pad-PC-Pad bilayer interdigitate completely, and the hydrophobic bilayer region has a thickness comparable to the length of a single phospholipid acyl chain. This leads to a stiff membrane with no spontaneous...

Université de Fribourg

Separate density and viscosity measurements of unknown liquid using quartz crystal microbalance

Tan, Feng ; Qiu, Du-Yu ; Guo, Lian-Ping ; Ye, Peng ; Zeng, Hao ; Jiang, Jun ; Tang, Yong ; Zhang, Yi-Cheng

In: AIP Advances, 2016, vol. 6, no. 9, p. 095313

Aqueous liquids have a wide range of applications in many fields. Basic physical properties like the density and the viscosity have great impacts on the functionalities of a given ionic liquid. For the millions kinds of existing liquids, only a few have been systematically measured with the density and the viscosity using traditional methods. However, these methods are limited to measure the...

Université de Fribourg

PKB/Akt-dependent regulation of inflammation in cancer

Tang, Fengyuan ; Wang, , Yuhua ; Hemmings, Brian A. ; Rüegg, Curzio ; Xue, Gongda

In: Seminars in Cancer Biology, 2017, p. -

Chronic inflammation is a major cause of human cancer. Clinical cancer therapies against inflammatory risk factors are strategically determined. To rationally guide a novel drug development, an improved mechanistic understanding on the pathological connection between inflammation and carcinogenesis is essential. PI3K-PKB signaling axis has been extensively studied and shown to be one of the...

Université de Fribourg

Cellulose whisker/epoxy resin nanocomposites

Tang, Liming ; Weder, Christoph

In: ACS Applied Materials and Interfaces, 2010, vol. 2, no. 4, p. 1073-1080

New nanocomposites composed of cellulose nanofibers or “whiskers” and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of ∼10 and ∼84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight...

Université de Fribourg

Complexities in financial network topological dynamics: modeling of emerging and developed stock markets

Tang, Yong ; Xiong, Jason Jie ; Jia, Zi-Yang ; Zhang, Yi-Cheng

In: Complexity, 2018, p. -

Policy makings and regulations of financial markets rely on a good understanding of the complexity of financial markets. There have been recent advances in applying data-driven science and network theory into the studies of social and financial systems. Financial assets and institutions are strongly connected and influence each other. It is essential to study how the topological structures of...

Université de Fribourg

Impact of monetary policy changes on the Chinese monetary and stock markets

Tang, Yong ; Luo, Yong ; Xiong, Jie ; Zhao, Fei ; Zhang, Yi-Cheng

In: Physica A: Statistical Mechanics and its Applications, 2013, vol. 392, no. 19, p. 4435–4449

The impact of monetary policy changes on the monetary market and stock market in China is investigated in this study. The changes of two major monetary policies, the interest rate and required reserve ratio, are analyzed in a study period covering seven years on the interbank monetary market and Shanghai stock market. We find that the monetary market is related to the macro economy trend and we...