Does fusion of domains from unrelated proteins affect their folding pathways and the structural changes involved in their function? A case study with the diphtheria toxin T domain

We investigated whether the structural and functional behaviorsof two unrelated protein domains were modified when fused. TheIgG-binding protein ZZ derived from staphylococcal protein Awas fused to the N- and/or C-terminus of the diphtheria toxintransmembrane domain (T). T undergoes a conformational changefrom a soluble native state at neutral pH to a molten globule-likestate at acidic pH, leading to its interaction with membranes.We found that this molten globule state was not connected tothe GdnHCl-induced unfolding pathway of T. The pH-induced transitionof T, and also the unfolding of T and ZZ at neutral and acidicpH, were unchanged whether the domains were isolated or fused.The position of ZZ, however, influenced the solubility of Tnear its pK_i. SPR measurements revealed that T has a high affinityfor membranes, isolated or within the fusion proteins (K_D<10^-11 M). This work shows that in the case of T and ZZ, thefusion of protein domains with different stabilities does notalter the structural changes involved in folding and function.This supports the use of T as a soluble membrane anchor.     

Determination expérimentale et prédiction des temps de circulation et de mélange pour un système d'agitation hélicoïdal

The homogenization efficiency of an atypicalhelical ribbon impeller was investigated. In a first part, circulation and mixting times for Newtonian fluidshave been determiend byuse of conductivity and thermal methods. A transferfunction model havebeen used to fit response curves obtained after tracer injections. The proposed model only depends on twoparametrs. Variations of these two parametrs have been correlated wtih the rotational impeller speed and the Reynolds numbervalue. This work allowsus to prdict, whatever flow regimes and process conditions (viscosity, rotatiional impeller speed), the mixing process performance.     

Enthalpies of Formation and Electronic Densities of States of Vanadium Borides

The structural and electronic properties of vanadium borides have been obtained from DFT calculations. The calculated value of the enthalpy of formation of C32-VB₂ compound is in good agreement with the experimental one. The calculated values of the lattice parameters at T = 0 K agree well with the experimental values. The total and partial electronic densities of states have been computed. Special features of the V electronic partial density of states have been evidenced and correlated to the local environment of the atoms and their charge.     

The 2006 pyroclastic deposits of Merapi Volcano, Java, Indonesia: High-spatial resolution IKONOS images and complementary ground based observations

On 16 June 2006 an overpass of IKONOS coincided with the emplacement of an active block-and-ash flow fed by a lava dome collapse at Merapi Volcano (Java, Indonesia). It was the first moving pyroclastic flow recorded on a satellite image. The very high-spatial resolution of the image indicated the extent and impact of pyroclastic material that was deposited during and prior to the day of image acquisition. A number of features associated with the hazardous block-and-ash flows emplaced in narrow, deep gorges were mapped, interpreted and analysed. The high-spatial-resolution IKONOS imagery worked extremely well for identifying pyroclastic deposits.The block-and-ash flow and surge deposits recognized in the IKONOS images include: (1) several channel-confined flow lobes and tongues in the box-shaped gorge; (2) thin ash-cloud surge deposit and knocked-down trees in constricted areas on both slopes of the gorge; (3) fan-like overbank deposits on the Gendol-Tlogo interfluves from which flows were re-routed in the Tlogo minor valley; (4) massive overbank flow lobes on the right bank of the Gendol River, which destroyed the village of Kaliadem 0.5 km from the main channel. A small part of this flow was re-channelled into the Opak tributary valley.The high-resolution IKONOS images also helped us to identify geomorphic obstacles that enabled flows to ramp up and spill out from the sinuous channel, as flow avulsion. Flow avulsions are dangerous as the redirect flows to unexpected areas away from the main channel. Valley fills from previous deposits, channel bends, and anthropogenic barriers in the channel (locally known as Sabo dams) influence the down valley passage of the flows. Sabo dams, originally built to ameliorate the effect of high sediment load streams, caused block-and-ash flows to avulse of the containing channel, and devastate populated areas.     

化学溶液方法制备涂层导体Ce_xLa_(1-x)O_2薄膜的研究

获得多功能单一过渡层是简化涂层导体多层结构的主要课题之一. 采用化学溶液方法制备La掺杂CeO₂过渡层,研究La掺杂量对CeO₂薄膜表面形貌和双轴取向生长的影响. 结果表明La掺杂量为10mol％的薄膜表面平整致密,且能保持锐利的双轴织构. 通过多次涂敷工艺,获得具有120nm厚的Ce_0.9La_0.1O₂过渡层. 采用脉冲激光沉积方法在Ce_0.9La_0.1O₂/NiW结构模板层上沉积了YBCO超导薄膜,其起始临界转变温度达到90.5K. 这表明采用化学溶液方法制备Ce_0.9La_0.1O₂薄膜是一种有前景的简化涂层导体多层结构的方法.     

An octree-based proxy for collision detection in large-scale particle systems

Particle systems are important building block for simulating vivid and detail-rich effects in virtual world.One of the most difficult aspects of particle systems has been detecting collisions between particles and mesh surface.Due to the huge computation,a variety of proxy-based approaches have been proposed recently to perform visually correct simulation.However,all either limit the complexity of the scene,fail to guarantee non-penetration,or are too slow for real-time use with many particles.In this paper,we propose a new octree-based proxy for colliding particles with meshes on the GPU.Our approach works by subdividing the scene mesh with an octree in which each leaf node associates with a representative normal corresponding to the normals of the triangles that intersect the node.We present a view-visible method,which is suitable for both closed and non-closed models,to label the empty leaf nodes adjacent to nonempty ones with appropriate back/front property,allowing particles to collide with both sides of the scene mesh.We show how collisions can be performed robustly on this proxy structure in place of the original mesh,and describe an extension that allows for fast traversal of the octree structure on the GPU.The experiments show that the proposed method is fast enough for real-time performance with millions of particles interacting with complex scenes.     

Robust Black-Box Modeling of Piezoelectric Actuators for Vibration Drilling Control

In this paper, we study a new modeling approach which is experimentally validated on piezoelectric actuators, in order to derive black-box pseudolinear models for the vibration drilling control. A common way is to use physical based approaches. However, sometimes, complex phenomena occur in the system due to atypical changes of the process behavior, output noise or some hard non-linearities. Therefore, identification methods to achieve the modeling task are adopted. The micro-displacements of the piezoelectric systems generate atypical data named observation outliers in the output signal, involving large errors named innovation outliers in the predicted output signal. Since the normal distribution of these estimation errors is disturbed, and present heavy tails, we choose here as model of contaminated distribution the gross error model (GEM) approach. In order to deal with the innovation outliers, we extend the noise interval range of the scaling factor, tuning the robust Huber’s ρ-function chosen. We propose from this function, a parameterized robust estimation criterion (PREC) and we give the asymptotic covariance matrix of the M-estimator for the Output Error (OE) model structure. A new decisional tool for the models quality, named L ₁-contribution function is proposed. Experimental results are presented and discussed.     

Centrifugal partition chromatography followed by HPLC for the isolation of cis-ε-viniferin,a resveratrol dimer newly extracted from a red Algerian wine

Grapes and related products are considered the major dietary sources of stilbenes. Among these compounds, trans-resveratrol is one of the most important in terms of biological activity, since it has been reported to prevent or to slow the progression of a wide variety of illnesses. We report for the first time the isolation and structure elucidation of cis-ε-viniferin, a biologically active resveratrol dihydrodimer from a red Algerian wine. The Merlot wine was fractionated by column chromatography followed by centrifugal partition chromatography (CPC) and then by reverse-phase semi-preparative HPLC. The structure of cis-ε-viniferin was elucidated by means of 1H NMR and 2D correlations. Cis-ε-viniferin concentrations were determined in wine samples originating from North Africa, most of which are commercially available in France. Stilbene quantification was based on an HPLC method with diode array detection. Unlike trans-ε-viniferin, cis-ε-viniferin was present in almost all wine samples studied and the concentrations ranged from 0.10 to 1.12 mg/l.     

Fortschritte in der Zerstäubungstrocknungs-Technologie

Progress in the technology of spray drying . Stringent quality demands on spray-dried goods have led to increasing use of nozzle spray dryers. In contrast to disk spray dryers, nozzle dryers yield microgranules and low-dust products directly. Although the process of nozzle spray drying is over 50 years old, the volume of available calculation material necessary for general application is sparse and limited mainly to special products or problems. This article presents new advances in the technology of nozzle spray dryers. An analytical formulation of the drying of a drop within the first drying phase decisive for granulation constitutes the basis of the general applicability of the fresh insights gained.     

Etude par diffraction X et microscopie electronique des composes inedits de formule AnBnO3n+2 dans les systems La2Ti2O7CaTiO3, Nd2Ti2O7CaTiO3 et Ca2Nb2O7CaTiO3

New compounds corresponding to the formula A_nB_nO_3n+2 with n = 4,5; 5 and 6 have been found in the two following systems Nd₂Ti₂O₇CaTiO₃ and Ca₂Nb₂O₇CaTiO₃. These compounds have been investigated by electron microscopy. The results obtained are in good agreement with our structural hypothesis.