Search results for " envelope"
showing 10 items of 253 documents
Computational Analysis of the Active Control of Incompressible Airfoil Flutter Vibration Using a Piezoelectric V-Stack Actuator
2021
The flutter phenomenon is a potentially destructive aeroelastic vibration studied for the design of aircraft structures as it limits the flight envelope of the aircraft. The aim of this work is to propose a heuristic design of a piezoelectric actuator-based controller for flutter vibration suppression in order to extend the allowable speed range of the structure. Based on the numerical model of a three degrees of freedom (3DOF) airfoil and taking into account the FEM model of a V-stack piezoelectric actuator, a filtered PID controller is tuned using the population decline swarm optimizer PDSO algorithm, and gain scheduling (GS) of the controller parameters is used to make the control adapti…
Assessment of determinants affecting the dual topology of hepadnaviral large envelope proteins
2004
For functional diversity, the large (L) envelope protein of hepatitis B virus (HBV) acquires a dual transmembrane topology via co-translational membrane integration of the S region and partial post-translational translocation of the preS subdomain. Because each process requires the second transmembrane segment (TM2), we explored the action of this determinant by using protease protection analysis of mutant L proteins. We demonstrated that neither the disruption of a leucine zipper-like motif by multiple alanine substitutions nor the flanking charges of TM2 affected the topological reorientation of L. The dispensability of both putative subunit interaction modules argues against a link betwe…
Factors influencing the interaction of herpes simplex virus glycoprotein C with the third component of complement.
1992
The factors influencing the interaction of herpes simplex virus (HSV) glycoprotein C (gC) with the third component of complement (C3) were investigated in this study. The ability of gC of HSV type 1 (gC-1) to bind to the C3b fragment of C3 was found to be influenced by cell specific processing of gC-1 in a different manner, binding being remarkably enhanced in some cell lines following removal of sialic acid residues. Testing several intertypic recombinants of HSV we found that only strains expressing gC-1 exhibited binding to C3b, even though their genome consisted mainly of HSV-2 sequences in some recombinants. Expression of type-2 glycoproteins gB, gD, gE, gG, gH, and gI did not alter th…
Maturation of IgG avidity to individual rubella virus structural proteins.
2001
Background: the structural proteins of rubella virus, the capsid protein C and the envelope glycoproteins E1 and E2 were produced in lepidopteran insect cells using baculovirus expression vectors. The C-terminal ends of the corresponding proteins were fused to a polyhistidine tag for easy and gentle purification by metal ion affinity chromatography. Objectives: to investigate the maturation of natural and vaccinal IgG avidity against individual authentic and recombinant rubella virus (RV) structural proteins. Study design the analysis was carried out using a modified immunoblotting technique where the purified baculovirus-expressed proteins were compared with authentic rubella virus protein…
Secretion and antigenicity of hepatitis B virus small envelope proteins lacking cysteines in the major antigenic region.
1995
Abstract Disulfide bonds are of crucial importance for the structure and antigenic properties of the hepatitis B virus (HBV) envelope. We have evaluated the role of the eight highly conserved cysteines of the major antigenic region for assembly, secretion, and antigenicity of the envelope proteins. Mutants carrying single or multiple substitutions of alanine for cysteine were analyzed using epitope tagging and transient expression in COS-7 cells. The only single cysteines found to be indispensable for efficient secretion were Cys-107 and Cys-138, but double mutation of Cys-137 and Cys-139 also created a block to secretion. Poorly secreted mutants formed aberrant oligomeric structures. The a…
T cells can present antigens such as HIV gp120 targeted to their own surface molecules
1988
To trigger class II-restricted T cells, antigen presenting cells have to capture antigens, process them and display their fragments in association with class II molecules. In most species, activated T cells express class II molecules; however, no evidence has been found that these cells can present soluble antigens. This failure may be due to the inefficient capture, processing or display of antigens in a stimulatory form by T-cells. The capture of a soluble antigen, which is achieved by nonspecific mechanisms in macrophages and dendritic cells, can be up to 10(3) times more efficient in the presence of surface receptors, such as surface immunoglobulin on B cells that specifically bind anti…
Polyclonal antibodies to mannan from yeast also recognize the carbohydrate structure of gp120 of the AIDS virus: an approach to raise neutralizing an…
1990
This study initiates a new method of developing an antigen which might be useful in the prevention of HIV-1 infection. Using a mannan preparation from Saccharomyces cerevisiae neutralizing antiserum was raised in rabbits which prevents HIV-1 infection in vitro up to a titre of 1:128. The corresponding antibody preparation neutralized the in vitro infectivity down to a concentration of 5 micrograms/ml. Analytical studies suggest that the antibodies are directed against the mannose residues of the HIV-1 glycoprotein (gp) 120 and its precursor gp 160.
Sulphoevernan, a polyanionic polysaccharide, and the narcissus lectin potently inhibit human immunodeficiency virus infection by binding to viral env…
1990
Sulphoevernan is a sulphated alpha-1----3, 1----4 polyglucan (Mr 20,000) with a helical structure. This compound effectively inhibits both human immunodeficiency virus type 1 (HIV-1) and type 2 infection of cells in vitro at concentrations around 0.5 micrograms/ml. Moreover, the compound completely inhibits HIV-1-induced syncytium formation at a concentration of 1 microgram/ml. Competition experiments with 35S-labelled sulphoevernan revealed that the mannose-specific lectin from Narcissus pseudonarcissus prevented binding of sulphoevernan to HIV-1, whereas the antibody OKT4A did not reduce the amount of sulphoevernan bound to MT-2 cells. These data indicate that the non-cytotoxic polymer su…
New Technologies for Adaptive Architecture
2019
Since the 1980s, the bioclimatic architecture has had the historical merit of having raised public and experts’ awareness on the importance of designing buildings with the purpose of solving the problem of energy saving. Nowadays, in the light of the most recent energy strategies policies, in force on an international and European scale, codified in EC Directive 31/2010 concerning the implementation of the Nearly Zer-Energy Buildings (NZEB), (Deru et al. 2006), the need for a new approach to redevelopment that focuses on environmental, climate and energy objectives with innovative technological solutions emerges, aimed at optimizing the passive bioclimatic behaviour of a building. In the wo…
Categorization of Extremely Brief Auditory Stimuli: Domain-Specific or Domain-General Processes?
2011
The present study investigated the minimum amount of auditory stimulation that allows differentiation of spoken voices, instrumental music, and environmental sounds. Three new findings were reported. 1) All stimuli were categorized above chance level with 50 ms-segments. 2) When a peak-level normalization was applied, music and voices started to be accurately categorized with 20 ms-segments. When the root-mean-square (RMS) energy of the stimuli was equalized, voice stimuli were better recognized than music and environmental sounds. 3) Further psychoacoustical analyses suggest that the categorization of extremely brief auditory stimuli depends on the variability of their spectral envelope in…