Home About us Contact
|
Home About us Contact | ||
|
|
||
Exterior
Terms modified by Exterior Selected AbstractsTransmission of cotton seed and boll rotting bacteria by the southern green stink bug (Nezara viridula L.)JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2007E.G. Medrano Abstract Aims:, To determine the ability of the southern green stink bug (SGSB) (Nezara viridula L.) to transmit Pantoea agglomerans into cotton (Gossypium hirsutum) bolls. Methods and Results:, An SGSB laboratory colony was kept on fresh green beans. A P. agglomerans variant resistant to rifampicin (Rif) (strain Sc 1-R) was used as the opportunistic cotton pathogen. Adult insects were individually provided green beans that were sterilized and then soaked in either sterile water or in a suspension of strain Sc 1-R. Insects were individually caged with an unopened greenhouse-grown cotton boll. After 2 days, live SGSB were collected, surfaced sterilized, ground, serially diluted, and then plated on nonselective media and media amended with Rif. Exterior and interior evidence of feeding on bolls was recorded 2 weeks after exposure to insects. Seed and lint tissue were harvested, ground, serially diluted, and then plated on media with and without Rif. Bacteria were recovered on nonselective media from all insects, and from seed and lint with signs of insect feeding at concentrations ranging from 102 to 109 CFU g,1 tissue. The Sc 1-R strain was isolated only from insects exposed to the marked strain and from seed and lint of respective bolls showing signs of insect feeding. Evidence of insect feeding on the exterior wall of the carpel was not always apparent (47%), whereas feeding was always observed (100%) on the interior wall in association with bacterial infections of seed and lint. Conclusions:,Nezara viridula readily ingested the opportunistic P. agglomerans strain Sc 1-R and transmitted it into unopened cotton bolls. Infections by the transmitted Sc 1-R strain caused rotting of the entire locule that masked internal carpel wounds incurred by insect feeding. Bacteria were recovered from penetration points by insects not exposed to the pathogen, but locule damage was limited to the area surrounding the feeding site (c. 3 mm). Significance and Impact of the Study:, This is the first study that demonstrates the ability of SGSB to acquire and transmit plant pathogenic bacteria into cotton bolls. [source] Essentialism in the absence of language?DEVELOPMENTAL SCIENCE, Issue 4 2010Evidence from rhesus monkeys (Macaca mulatta) We explored whether rhesus monkeys (Macaca mulatta) share one important feature of human essentialist reasoning: the capacity to track category membership across radical featural transformations. Specifically, we examined whether monkeys , like children (Keil, 1989) , expect a transformed object to have the internal properties of its original category. In two experiments, monkeys watched as an experimenter visually transformed a familiar fruit (e.g. apple) into a new kind of fruit (e.g. coconut) either by placing a fruit exterior over the original, or by removing an exterior shell and revealing the inside kind of fruit. The experimenter then pretended to place an inside piece of the transformed fruit into a box which the monkey was allowed to search. Results indicated that monkeys searched the box longer when they found a piece of fruit inconsistent with the inside kind, suggesting that the monkeys expected that the inside of the transformed fruit would taste like the innermost kind they saw. These results suggest that monkeys may share at least one aspect of psychological essentialism: They maintain category-specific expectations about an object's internal properties even when that object's external properties change. These results therefore suggest that some essentialist expectations may emerge in the absence of language, and thus raise the possibility that such tendencies may emerge earlier in human development than has previously been considered. [source] A seismic retrofit method by connecting viscous dampers for microelectronics factoriesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2007Jenn-Shin Hwang Abstract The implementation of viscous dampers to microelectronics factories has been previously proved not to affect the micro-vibration of the factories in operation so that the vibration-sensitive manufacturing process will not be interfered. Therefore, a seismic retrofit strategy which employs the viscous dampers installed in between the exterior and interior structures of the ,fab' structure is proposed in the study. The design formulas corresponding to the proposed retrofit method are derived using the non-proportional damping theory. Based on the study, it is found that the added damping ratio to the fab structure depends greatly on the frequency ratio of the two structures in addition to the damping coefficients of the added dampers. Outside the bandwidth of the frequency ratio in which the added damping ratio is very sensitive to the variation of the frequency ratio, the added damping ratio can be well captured using the classical damping theory. Copyright © 2007 John Wiley & Sons, Ltd. [source] Development and validation of a metallic haunch seismic retrofit solution for existing under-designed RC frame buildingsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2006Stefano Pampanin Abstract The feasibility and efficiency of a seismic retrofit solution for existing reinforced concrete frame systems, designed before the introduction of modern seismic-oriented design codes in the mid 1970s, is conceptually presented and experimentally investigated. A diagonal metallic haunch system is introduced at the beam,column connections to protect the joint panel zone from extensive damage and brittle shear mechanisms, while inverting the hierarchy of strength within the beam,column subassemblies and forming a plastic hinge in the beam. A complete step-by-step design procedure is suggested for the proposed retrofit strategy to achieve the desired reversal of strength hierarchy. Analytical formulations of the internal force flow at the beam,column-joint level are derived for the retrofitted joints. The study is particularly focused on exterior beam,column joints, since it is recognized that they are the most vulnerable, due to their lack of a reliable joint shear transfer mechanism. Results from an experimental program carried out to validate the concept and the design procedure are also presented. The program consisted of quasi-static cyclic tests on four exterior, , scaled, beam,column joint subassemblies, typical of pre-1970 construction practice using plain round bars with end-hooks, with limited joint transverse reinforcement and detailed without capacity design considerations. The first (control specimen) emulated the as-built connection while the three others incorporated the proposed retrofitted configurations. The experimental results demonstrated the effectiveness of the proposed solution for upgrading non-seismically designed RC frames and also confirmed the applicability of the proposed design procedure and of the analytical derivations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Workers in the New Economy: Transformation as Border CrossingETHOS, Issue 1 2006Valerie Walkerdine In this article, I seek to make an intervention in debates between psycho-logical and postmodern anthropology by engaging with the theme of border crossing. I argue that the theme of the border is one that fundamentally instantiates a separation between interior and exterior with respect to subjectivity, itself a funda-mental transformation and a painful and difficult border. This is related to a Cartesian distinction critiqued in this article. How the distinction between interior and exterior may be transcended is discussed in relation to examples of transformation from the crossing of class borders to the production and regulation of workers in a globalized and neoliberal economy. I begin with reference to postwar transformations of class with its anxious borders and go on to think about changes in the labor market and how these demand huge transformations that tear apart communities, destroy work-places, and sunder the sense of safety and stability that those gave. Advanced liberalism or neoliberalism brings with it a speeding up of the transformations of liberalism in which subjects are constantly invoked as self-contained, with a trans-portable self that must be produced through the developmental processes of personality and rationality. This self must be carried like a snail carries a shell. It must be coherent yet mutable, fixed yet multiple and flexible. But this view of the subject covers over the many connections that make subjectivity possible. I conclude by ask-ing what it would mean to rethink this issue of the production of safe spaces beyond an essentialist psychological conception of only one mother child space, separated from the social world, as having the power to produce feelings of safety? I end the article with an argument for a relational approach to subjectivity and sociality. [subjectivity, relationality, neoliberalism, workers, class] [source] Toward an Allosteric Metallated ContainerEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2009Helga Szelke Abstract Polytopic ligands L1 and L2 in which three 2,2,-bipyridine units are linked to a central tris(pyrid-2-yl)amine (L1) or tris(pyrid-2-yl)methanol (L2) moiety by alkyl spacers were prepared by multistep organic syntheses. The parent tris(pyrid-2-yl)-type ligands were shown to be modest-to-good chelators for Zn2+ and Cu2+ ions in solution, and bi- and tridentate N-coordination was confirmed by crystal structures of CuII and RuII complexes, respectively. FeII and RuII smoothly form stable, cage-like 1:1 complexes with L1 and L2, in which the metal ion is coordinated to the tris(bpy) site of the ligands. The vacant tris(pyrid-2-yl) site of these complexes is, however, a poor donor site for Zn2+ and Cu2+ ions. In addition, FeII modulates the coordination behaviour of the tris(pyrid-2-yl) site toward Zn2+: Whereas tris(5-methylpyrid-2-yl)amine forms a 2:1 complex with Zn2+ in CH2Cl2, [Fe(L1)]2+ forms a 1:1 Zn complex. Spectrophotometric titrations suggest that [Fe(L2)]2+ forms a polynuclear Zn2+ complex in CH2Cl2, possibly involving bridging coordination of the alcohol OH group, which contrasts the smooth formation of a 2:1 complex of the parent tris(pyrid-2-yl)-type ligand with Zn. FeII might therefore be considered as an allosteric effector, which modulates the metal binding properties of the second tris(pyrid-2-yl) site of L1 and L2. Contrary to expectation, Zn2+ and Cu2+ appear to associate weakly with donor atoms directed toward the exterior of the cage-like complexes [Fe(Ln)]2+ and [Ru(L1)]2+, rather than locating in the interior of the container by tripodal coordination to the tris(pyrid-2-yl) site.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Endogenous microflora in turbid virgin olive oils and the physicochemical characteristics of these oilsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2008Anastasios Koidis Abstract Cloudy olive oil, the fresh olive juice, is an intermediate form before full precipitation of freshly produced olive oil. Some consumers prefer it because they consider it as more natural and less processed. The cloudy form can persist for several months. The oil is a sort of dispersion/suspension system which can be also described as a micro-emulsion/suspension. Water micro-droplets were found to have a size ranging from 1 to 5,µm. Cloudiness is due to the low water content and the presence of natural emulsifiers in the oil. The suspension is formed by solid particles (5,60,µm) deriving from the olive fruit. They are present in small amounts (12,460,mg/kg oil). In the newly produced olive oil, containing 0.17,0.49% water, a number of microorganisms of different types (bacteria, yeasts, moulds) were found to survive, but at very low concentrations (<3,log,cfu/mL oil). They originate from the exterior of the fruit (epiphytic microflora) and their presence is considered natural. Their enzyme activities do not seem to affect the quality of the final product. [source] Synthetic Hydrophilic Materials with Tunable Strength and a Range of Hydrophobic Interactions,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Olha Hoy Abstract The ability to vary, adjust, and control hydrophobic interactions is crucial in manipulating interactions between biological objects and the surface of synthetic materials in aqueous environment. To this end a grafted polymer layer (multi-component mixed polymer brush) is synthesized that is capable of reversibly exposing nanometer-sized hydrophobic fragments at its hydrophilic surface and of tuning, turning on, and turning off the hydrophobic interactions. The reversible switching occurs in response to changes in the environment and alters the strength and range of attractive interactions between the layer and hydrophobic or amphiphilic probes in water. The grafted layer retains its overall hydrophilicity, while local hydrophobic forces enable the grafted layer to sense and attract the hydrophobic domains of protein molecules dissolved in the aqueous environment. The hydrophobic interactions between the material and a hydrophobic probe are investigated using atomic force microscopy measurements and a long-range attractive and contact-adhesive interaction between the material and the probe is observed, which is controlled by environmental conditions. Switching of the layer exterior is also confirmed via protein adsorption measurements. [source] Tailoring Macromolecular Expression at Polymersome SurfacesADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Adam Blanazs Abstract A series of amphiphilic ABC triblock copolymers are synthesized by atom transfer radical polymerization, wherein the ,A' and ,C' blocks are hydrophilic and the pH-sensitive ,B' block can be switched from hydrophilic in acidic solution to hydrophobic at pH 7. Careful addition of base to the molecularly dissolved copolymer in acidic solution readily induces the self-assembly of such triblock copolymers at around neutral pH to form pH-sensitive polymersomes (a.k.a. vesicles) with asymmetric membranes. By systematic variation of the relative volume fractions of the ,A' and ,C' blocks, the chemical nature of the polymer chains expressed at the interior or exterior corona of the polymersomes can be selected. Treatment of primary human dermal fibroblast cells with these asymmetric polymersomes demonstrates the biological consequences of such spatial segregation, with both polymersome cytotoxicity and endocytosis rates being dictated by the nature of the polymersome surface chemistry. The pH-sensitive nature of the polymersomes readily facilitates their dissociation after endocytosis due to the relatively low endosomal pH, which results in the rapid release of an encapsulated dye. Selective binding of anionic substrates such as DNA within the inner cationic polymersome volume, coupled with a biocompatible exterior, leads to potential gene delivery applications for these pH-sensitive asymmetric nanovectors. [source] Interleukin-6 Induction by Helicobacter pylori in Human Macrophages is Dependent on PhagocytosisHELICOBACTER, Issue 3 2006Stefan Odenbreit Abstract Background:, The colonization of the gastric mucosa with Helicobacter pylori is accompanied by elevated levels of proinflammatory cytokines, such as interleukin-1 (IL-1), IL-6, and IL-8. The aim of our study was to determine the mechanisms of IL-6 stimulation in phagocytes upon H. pylori infection. Materials and Methods:, We investigated the secretion of IL-6 by different professional phagocytes from murine and human origin, including granulocyte- and monocyte-like cells and macrophages derived from human peripheral blood monocytes (PBMCs). The influence of viability, phagocytosis, and the impact of different subcellular fractions of H. pylori bacteria were evaluated. Results:, IL-6 levels induced by H. pylori were low in cell lines derived from murine and human monocytes and in human granulocyte-like cells. By contrast, macrophages derived from human PBMCs were highly responsive to both H. pylori and Escherichia coli. IL-6 induction was blocked by inhibition of actin-dependent processes prior to infection with H. pylori, but not with E. coli or E. coli lipopolysaccharide (LPS). Using cell fractionation, the most activity was found in the H. pylori membrane. H. pylori LPS exhibited a 103 - to 104 -fold lower biologic activity than E. coli LPS, suggesting a minor role for toll-like receptor 4 (TLR4)-mediated signalling from the exterior. Conclusions:, From these data, we conclude that macrophages may be a major source of IL-6 in the gastric mucosa upon H. pylori infection. The IL-6 induction by H. pylori in these cells is a multifactorial process, which requires the uptake and presumably degradation of H. pylori bacteria. [source] Electrostatic BEM for MEMS with thin beamsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 6 2005Zhongping Bao Abstract Micro-electro-mechanical (MEM) and nano-electro-mechanical (NEM) systems sometimes use beam- or plate-shaped conductors that can be very thin,with h/L,,,(10,2,10,3) (in terms of the thickness h and length L of a beam or the side of a square pate). Conventional boundary element method (BEM) analysis of the electric field in a region exterior to such thin conductors can become difficult to carry out accurately and efficiently,especially since MEMS analysis requires computation of charge densities (and then surface tractions) separately on the top and bottom surfaces of such objects. A new boundary integral equation (BIE) is derived in this work that, when used together with the standard BIE with logarithmically singular kernels, results in a powerful technique for the BEM analysis of such problems with thin beams. This new approach, in fact, works best for very thin beams. This thin beam BEM is derived and discussed in this work. Copyright © 2005 John Wiley & Sons, Ltd. [source] A hybrid immersed boundary and material point method for simulating 3D fluid,structure interaction problemsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2008Anvar Gilmanov Abstract A numerical method is developed for solving the 3D, unsteady, incompressible Navier,Stokes equations in curvilinear coordinates containing immersed boundaries (IBs) of arbitrary geometrical complexity moving and deforming under forces acting on the body. Since simulations of flow in complex geometries with deformable surfaces require special treatment, the present approach combines a hybrid immersed boundary method (HIBM) for handling complex moving boundaries and a material point method (MPM) for resolving structural stresses and movement. This combined HIBM & MPM approach is presented as an effective approach for solving fluid,structure interaction (FSI) problems. In the HIBM, a curvilinear grid is defined and the variable values at grid points adjacent to a boundary are forced or interpolated to satisfy the boundary conditions. The MPM is used for solving the equations of solid structure and communicates with the fluid through appropriate interface-boundary conditions. The governing flow equations are discretized on a non-staggered grid layout using second-order accurate finite-difference formulas. The discrete equations are integrated in time via a second-order accurate dual time stepping, artificial compressibility scheme. Unstructured, triangular meshes are employed to discretize the complex surface of the IBs. The nodes of the surface mesh constitute a set of Lagrangian control points used for tracking the motion of the flexible body. The equations of the solid body are integrated in time via the MPM. At every instant in time, the influence of the body on the flow is accounted for by applying boundary conditions at stationary curvilinear grid nodes located in the exterior but in the immediate vicinity of the body by reconstructing the solution along the local normal to the body surface. The influence of the fluid on the body is defined through pressure and shear stresses acting on the surface of the body. The HIBM & MPM approach is validated for FSI problems by solving for a falling rigid and flexible sphere in a fluid-filled channel. The behavior of a capsule in a shear flow was also examined. Agreement with the published results is excellent. Copyright © 2007 John Wiley & Sons, Ltd. [source] Hyperbolic Penalty: A New Method for Nonlinear Programming with InequalitiesINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 6 2001Adilson Elias Xavier This work intends to present and to analyze a new penalty method that purposes to solve the general nonlinear programming problem subject to inequality constraints. The proposed method has the important feature of being completely differentiable and combines features of both exterior and interior penalty methods. Numerical results for some problems are commented on. [source] AFM Investigation of Mechanical Properties of DentinISRAEL JOURNAL OF CHEMISTRY, Issue 2 2008Sidney R. Cohen Mechanical properties of peritubular dentin were investigated using scanning probe microscopy techniques, namely Nanoindentation and Band Excitation. Particular attention was directed to the possible existence of a gradient in these properties moving outward from the tubular lumen to the junction with the intertubular dentin. Finite element analysis showed that the influence of the boundaries is small relative to the effects observed. Thus, these results strongly support the concept of a lowering of modulus and hardness from the tubular exterior to its periphery, which appear to correlate with graded changes in the mineral content. [source] "The Outside Is the Result of an Inside": Some Sources of One of Modernism's Most Persistent DoctrinesJOURNAL OF ARCHITECTURAL EDUCATION, Issue 1 2002THOMAS L. SCHUMACHER One of the most pervasive doctrines of composition for modernism was the necessary correspondence between the interior and the exterior as expressed in Le Corbusier's maxim, "The outside is the result of an inside." Many Modern movement architects interpreted this maxim as requiring that both "space" and "program" be expressed on the exterior of their buildings. Although Modern movement architects and theorists themselves wrote little on this subject, a number of earlier writings, including some nineteenth- and twentieth-century books by traditionalists, reveal the academic roots of these precepts. This paper traces the development of these ideas. [source] Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactorJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2002Vassilios I. Sikavitsas Abstract The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague,Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L -lactic- co -glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the accelerated proliferation and differentiation of marrow stromal osteoblasts, and the localization of the enhanced mineralization on the external surface of the scaffolds. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 136,148, 2002 [source] What youngsters say about adults: seedling roots reflect clonal traits of adult plantsJOURNAL OF ECOLOGY, Issue 3 2007MARIE, MILAUEROVÁ Summary 1Grime's theory on plant strategies predicts that the set of traits present in established plants is not correlated with that found in the regenerative stage of the life cycle. We tested this prediction and further investigated whether clonal growth traits, which are found in adult plants but also affect regeneration, are correlated with seedling traits. 2We characterized seedling root systems by their total length, number of root tips and several architectural parameters (length of exterior and interior root links and two topological indices). These below-ground traits were supplemented by the ratio of leaf area to root length, representing relative investment into photosynthesizing surface. We compared seedling traits with clonal growth traits, adult plant heights, and species positions on gradients of nitrogen and water availability. 3Plant species with limited horizontal spread by clonal growth exhibited a larger relative investment in photosynthetic area and also developed larger root systems as seedlings. 4Seedlings of species with taller shoots and those which occur naturally at nutrient-rich sites developed both larger roots and more dichotomously branched root systems (with higher total length and more branches). 5Taking phylogenetic inertia into account showed that this explained large parts of the variation in seedling traits. Relationships between clonal spread and seedling traits were strengthened by phylogenetic correction. 6Our study shows that some of the traits of clonal growth affect both the established and the regenerative stages of the life cycle, suggesting that an evolutionary trade-off exists between the ability to spread clonally and performance at the seedling stage. Species not able to escape from less favourable conditions by extensive clonal spread seem to be more able to exploit the location in which they germinate. [source] Modular, self-assembling peptide linkers for stable and regenerable carbon nanotube biosensor interfaces,JOURNAL OF MOLECULAR RECOGNITION, Issue 4 2006Mark R. Contarino Abstract As part of an effort to develop nanoelectronic sensors for biological targets, we tested the potential to incorporate coiled coils as metallized, self-assembling, site-specific molecular linkers on carbon nanotubes (CNTs). Based on a previously conceived modular anchor-probe approach, a system was designed in which hydrophobic residues (valines and leucines) form the interface between the two helical peptide components. Charged residues (glutamates and arginines) on the borders of the hydrophobic interface increase peptide solubility, and provide stability and specificity for anchor-probe assembly. Two histidine residues oriented on the exposed hydrophilic exterior of each peptide were included as chelating sites for metal ions such as cobalt. Cysteines were incorporated at the peptide termini for oriented, thiol-mediated coupling to surface plasmon resonance (SPR) biosensor surfaces, gold nanoparticles or CNT substrates. The two peptides were produced by solid phase peptide synthesis using Fmoc chemistry: an acidic 42-residue peptide E42C, and its counterpart in the heterodimer, a basic 39-residue peptide R39C. The ability of E42C and R39C to bind cobalt was demonstrated by immobilized metal affinity chromatography and isothermal titration calorimetry. SPR biosensor kinetic analysis of dimer assembly revealed apparent sub-nanomolar affinities in buffers with and without 1,mM CoCl2 using two different reference surfaces. For device-oriented CNT immobilization, R39C was covalently anchored to CNT tips via a C-terminal cysteine residue. Scanning electron microscopy was used to visualize the assembly of probe peptide (E42C) N-terminally labeled with 15,nm gold nanoparticles, when added to the R39C-CNT surface. The results obtained open the way to develop CNT tip-directed recognition surfaces, using recombinant and chemically synthesized chimeras containing binding epitopes fused to the E42C sequence domain. Copyright © 2006 John Wiley & Sons, Ltd. [source] Microgel-Based Engineered Nanostructures and Their Applicability with Template-Directed Layer-by-Layer Polyelectrolyte Assembly in Protein EncapsulationMACROMOLECULAR BIOSCIENCE, Issue 5 2005Dinesh B. Shenoy Abstract Summary: A novel strategy for the fabrication of microcapsules is elaborated by employing biomacromolecules and a dissolvable template. Calcium carbonate (CaCO3) microparticles were used as sacrificial templates for the two-step deposition of polyelectrolyte coatings by surface controlled precipitation (SCP) followed by the layer-by-layer (LbL) adsorption technique to form capsule shells. When sodium alginate was used for inner shell assembly, template decomposition with an acid resulted in simultaneous formation of microgel-like structures due to calcium ion-induced gelation. An extraction of the calcium after further LbL treatment resulted in microcapsules filled with the biopolymer. The hollow as well as the polymer-filled polyelectrolyte capsules were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and scanning force microscopy (SFM). The results demonstrated multiple functionalities of the CaCO3 core , as supporting template, porous core for increased polymer accommodation/immobilization, and as a source of shell-hardening material. The LbL treatment of the core-inner shell assembly resulted in further surface stabilization of the capsule wall and supplementation of a nanostructured diffusion barrier for encapsulated material. The polymer forming the inner shell governs the chemistry of the capsule interior and could be engineered to obtain a matrix for protein/drug encapsulation or immobilization. The outer shell could be used to precisely tune the properties of the capsule wall and exterior. Confocal laser scanning microscopy (CLSM) image of microcapsules (insert is after treating with rhodamine 6G to stain the capsule wall). [source] Scattering from infinite rough tubular surfacesMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 4 2007Xavier Claeys Abstract We study the Helmholtz equation in the exterior of an infinite perturbed cylinder with a Dirichlet boundary condition. Existence and uniqueness of solutions are established using the variational technique introduced (SIAM J. Math. Anal. 2005; 37(2):598,618). We also provide stability estimates with explicit dependence of the constants in terms of the frequency and the perturbed cylinder thickness. Copyright © 2006 John Wiley & Sons, Ltd. [source] On non-stationary viscous incompressible flow through a cascade of profilesMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 16 2006Miloslav Feistauer Abstract The paper deals with theoretical analysis of non-stationary incompressible flow through a cascade of profiles. The initial-boundary value problem for the Navier,Stokes system is formulated in a domain representing the exterior to an infinite row of profiles, periodically spaced in one direction. Then the problem is reformulated in a bounded domain of the form of one space period and completed by the Dirichlet boundary condition on the inlet and the profile, a suitable natural boundary condition on the outlet and periodic boundary conditions on artificial cuts. We present a weak formulation and prove the existence of a weak solution. Copyright © 2006 John Wiley & Sons, Ltd. [source] Identification of objects in an acoustic wave guide inversion II: Robin,Dirichlet conditionsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 4 2006Doo-Sung Lee Abstract In this paper we investigate the unknown body problem in a wave guide where one boundary has a pressure release condition and the other an impedance condition. The method used in the paper for solving the unknown body inverse problem is the intersection canonical body approximation (ICBA). The ICBA is based on the Rayleigh conjecture, which states that every point on an illuminated body radiates sound from that point as if the point lies on its tangent sphere. The ICBA method requires that an analytical solution be known exterior to a canonical body in the wave guide. We use the sphere of arbitrary centre and radius in the wave guide as our canonical body. We are lead then to analytically computing the exterior solution for a sphere between two parallel plates. We use the ICBA to construct solutions at points ranging over the suspected surface of the unknown object to reconstruct the unknown object using a least-squares matching of computed, acoustic field against the measured, scattered field. Copyright © 2005 John Wiley & Sons, Ltd. [source] Spectral theory and iterative methods for the Maxwell system in nonsmooth domainsMATHEMATISCHE NACHRICHTEN, Issue 6 2010Irina Mitrea Abstract We study spectral properties of boundary integral operators which naturally arise in the study of the Maxwell system of equations in a Lipschitz domain , , ,3. By employing Rellich-type identities we show that the spectrum of the magnetic dipole boundary integral operator (composed with an appropriate projection) acting on L2(,,) lies in the exterior of a hyperbola whose shape depends only on the Lipschitz constant of ,. These spectral theory results are then used to construct generalized Neumann series solutions for boundary value problems associated with the Maxwell system and to study their rates of convergence (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Artemisinin Derivatives with Antimalarial Activity against Plasmodium falciparum Designed with the Aid of Quantum Chemical and Partial Least Squares MethodsMOLECULAR INFORMATICS, Issue 8 2003Abstract Artemisinin derivatives with antimalarial activity against Plasmodium falciparum resistant to mefloquine are designed with the aid of Quantum Chemical and Partial Least Squares Methods. The PLS model with three principal components explaining 89.55% of total variance, Q2=0.83 and R2=0.92 was obtained for 14/5 molecules in the training/external validation set. The most important descriptors for the design of the model were one level above the lowest unoccupied molecular orbital energy (LUMO+1), atomic charges in atoms C9 and C11 (Q9) and (Q11) respectively, the maximum number of hydrogen atoms that might make contact with heme (NH) and RDF030,m (a radial distribution function centered at 3.0,Ĺ interatomic distance and weighted by atomic masses). From a set of ten proposed artemisinin derivatives, a new compound (26), was predicted with antimalarial activity higher than the compounds reported in literature. Molecular graphics and modeling supported the PLS results and revealed heme-ligand and protein-ligand stereoelectronic relationships as important for antimalarial activity. The most active 26 and 29 in the prediction set possess substituents at C9 able to extend to hemoglobin exterior, what determines the high activity of these compounds. [source] Of blood, brains and bacteria, the Amt/Rh transporter family: emerging role of Amt as a unique microbial sensorMOLECULAR MICROBIOLOGY, Issue 1 2009Pier-Luc Tremblay Summary Members of the Amt/Rh family of transporters are found almost ubiquitously in all forms of life. However, the molecular state of the substrate (NH3 or NH4+) has been the subject of active debate. At least for bacterial Amt proteins, the model emerging from computational, X-ray crystal and mutational analysis is that NH4+ is deprotonated at the exterior, conducted through the membrane as NH3, and reprotonated at the cytoplasmic interface. A proton concomitantly is transferred from the exterior to the interior, although the mechanism is unclear. Here we discuss recent evidence indicating that an important function of at least some eukaryotic and bacterial Amts is to act as ammonium sensors and regulate cellular metabolism in response to changes in external ammonium concentrations. This is now well documented in the regulation of yeast pseudohyphal development and filamentous growth. As well, membrane sequestration of GlnK, a PII signal transduction protein, by AmtB has been shown to regulate nitrogenase in some diazotrophs, and nitrogen metabolism in some Gram-positive bacteria. Formation of GlnK,AmtB membrane complexes might have other, as yet undiscovered, regulatory roles. This possibility is emphasized by the discovery in some genomes of genes for chimeric Amts with fusions to various regulatory elements. [source] Origin and function of the two major tail proteins of bacteriophage SPP1MOLECULAR MICROBIOLOGY, Issue 3 2008Isabelle Auzat Summary The majority of bacteriophages have a long non-contractile tail (Siphoviridae) that serves as a conduit for viral DNA traffic from the phage capsid to the host cell at the beginning of infection. The 160-nm-long tail tube of Bacillus subtilis bacteriophage SPP1 is shown to be composed of two major tail proteins (MTPs), gp17.1 and gp17.1*, at a ratio of about 3:1. They share a common amino-terminus, but the latter species has ,10 kDa more than gp17.1. A CCC.UAA sequence with overlapping proline codons at the 3, end of gene 17.1 drives a programmed translational frameshift to another open reading frame. The recoding event generates gp17.1*. Phages carrying exclusively gp17.1 or gp17.1* are viable, but tails are structurally distinct. gp17.1 and the carboxyl-terminus of gp17.1* have a distinct evolutionary history correlating with different functions: the polypeptide sequence identical in the two proteins is responsible for assembly of the tail tube while the additional module of gp17.1* shields the structure exterior exposed to the environment. The carboxyl-terminal extension is an elaboration present in some tailed bacteriophages. Different extensions were found to combine in a mosaic fashion with the MTP essential module in a subset of Siphoviridae genomes. [source] Novel ultrastructures of Treponema primitia and their implications for motilityMOLECULAR MICROBIOLOGY, Issue 6 2008Gavin E. Murphy Summary Members of the bacterial phylum Spirochaetes are generally helical cells propelled by periplasmic flagella. The spirochete Treponema primitia is interesting because of its mutualistic role in the termite gut, where it is believed to cooperate with protozoa that break down cellulose and produce H2 as a by-product. Here we report the ultrastructure of T. primitia as obtained by electron cryotomography of intact, frozen-hydrated cells. Several previously unrecognized external structures were revealed, including bowl-like objects decorating the outer membrane, arcades of hook-shaped proteins winding along the exterior and tufts of fibrils extending from the cell tips. Inside the periplasm, cone-like structures were found at each pole. Instead of the single peptidoglycan layer typical of other Gram-negative bacteria, two distinct periplasmic layers were observed. These layers formed a central open space that contained two flagella situated adjacent to each other. In some areas, the inner membrane formed flattened invaginations that protruded into the cytoplasm. High-speed light microscopic images of swimming T. primitia cells showed that cell bodies remained rigid and moved in a helical rather than planar motion. Together, these findings support the ,rolling cylinder' model for T. primitia motility that posits rotation of the protoplasmic cylinder within the outer sheath. [source] Behaviour of torsional Alfvén waves and field line resonance on rotating magnetarsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005Taishi Okita ABSTRACT Torsional Alfvén waves are likely excited with bursts in rotating magnetars. These waves are probably propagated through corotating atmospheres toward a vacuum exterior. We have studied the physical effects of the azimuthal wavenumber and the characteristic height of the plasma medium on wave transmission. In this work, explicit calculations were carried out based on the three-layered cylindrical model. We found that the coupling strength between the internal shear and the external Alfvén modes is drastically enhanced, when resonance occurs in the corotating plasma cavity. The spatial structure of the electromagnetic fields in the resonance cavity is also investigated when Alfvén waves exhibit resonance. [source] Retailers' tagging practices: a potential liability?PACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2004Laura Bix Abstract This study investigates the coverage of federally mandated information on over-the-counter (OTC) drug labels by electronic article surveillance (EAS) tags applied to the exterior of cartons. Using adult-strength analgesics containing acetaminophen as a case study, researchers investigated the issue in Houston, Texas (24 stores) and Lansing, Michigan (33 stores). The information obscured by EAS tags was identified and classified for a total of 849 packages using a standardized data collection instrument. The results indicated that 293 packages examined, or 34.5%, had information mandated by the US Food and Drug Administration (US FDA) fully or partially obscured by the EAS tags. Retailers and manufacturers should be aware of such practices to reduce potential liability. Recommendations for improving EAS tag usage on OTC products are presented. Copyright © 2004 John Wiley & Sons, Ltd. [source] AMMONOID SHELL STRUCTURES OF PRIMARY ORGANIC COMPOSITIONPALAEONTOLOGY, Issue 6 2007CHRISTIAN KLUG Abstract:, Palaeozoic and Mesozoic cephalopod conchs occasionally reveal dark organic coatings at the aperture. A number of these coatings, including still unrecorded examples, are described, figured and interpreted herein. On the basis of elemental analysis, actualistic comparison and a comparison with Triassic bivalves, some of these coatings are shown to consist of apatite and primarily probably of conchiolin (and also probably melanin). In several Mesozoic ammonoid genera such as Paranannites, Psiloceras, Lytoceras, Phylloceras, Harpoceras and Chondroceras, some of these coatings (recorded herein for most of these taxa for the first time) are interpreted as a structure similar to the black band, which was previously known only from Recent Allonautilus and Nautilus. In contrast to these nautilid genera, however, the organic material of some Mesozoic ammonoids was not deposited on the inside of the shell but externally, albeit positioned at the terminal aperture as in Recent nautilids. Some ammonoids of Carboniferous and Triassic age show several such bands at more or less regular angular distances on the ultimate whorls and at the aperture, e.g. Nomismoceras, Gatherites, Owenites, Paranannites, Juvenites and Melagathiceratidae gen. et sp. nov. Triassic material from Oman shows that the black coating was probably secreted from the inside, because the position of this organic deposit changes from interior to exterior in an anterior direction (i.e. adaperturally). This structure has previously been referred to as a ,false colour pattern' and is here interpreted as having been formed at an interim aperture or megastria (,alter Mundrand'). All structures discussed in the paper are considered to have been secreted by a single organ and to have been initiated by some form of stress or adverse conditions. Thus, certain environmental parameters and growth anomalies appear to have influenced their formation. [source] | |||||||||||||||||||||||||||||||||||||