Improvement, deterioration, and optimal replacement underage-replacement with minimal repair

Improvement and deterioration for a repairable system are studied, in particular in terms of the effect of ageing on the distribution of the time to first failure under a nonhomogeneous Poisson process. For a repairable system undergoing minimal repair, the optimal replacement time under the age replacement policy is discussed     

Evaluating industrial grade functionalized multiwalled carbon nanotubes by X-ray photoelectron spectroscopy

Utilization of carbon nanotubes in various applications is a function of their dispersion in respective matrix which effectively depends on the functionalization employed. Functional group distribution on Carbon Nanotube surface is usually a complex mixture of groups depending on the oxidizing agent employed. In this regard, nine varieties of Industrial grade multiwalled carbon nanotubes belonging to 10–30, 20–40 and 50–80?nm outer diameter ranges but differing in functionality (carboxyl and hydroxyl) were analyzed. X-ray photoelectron spectroscopy was employed to quantify the different functionalities on pristine, hydroxyl and carboxyl functionalized multiwalled carbon nanotubes and high-resolution transmission electron microscopy was used to image the internal structure including the side wall damage in functionalized varieties. X-ray photoelectron spectroscopy measurements on nine batches have suggested the presence of carbonyl, carboxyl and hydroxyl functional groups on all multiwalled carbon nanotubes in different proportions. This implies that it is not possible to have exclusive hydroxyl or carboxyl functionalization on a CNT surface Additionally, comparison is drawn between already existing deconvolution procedures from literature.     

Free convection in a non-Newtonian fluid along a horizontal plate embedded in porous media with internal heat generation

Similarity solutions for the problem of free convection flow over a non-isothermal horizontal plate embedded in porous media are investigated in the presence of internal heat generation. The porous medium is saturated with non-Newtonian power law fluid. Numerical results are obtained for the effect of power law temperature profile and fluid index on the heat transfer characteristics.     

Efficient representation and algebraic manipulation of infinite relations in paraconsistent databases

Paraconsistent information is information that is incomplete and/or inconsistent. A data model for handling paraconsistent information in relational databases has recently been developed. In this paper, we show that a DBMS based on paraconsistent relations must be capable of handling infinite relations. We also identify classes of infinite paraconsistent relations whose members can be effectively represented and manipulated. We show that the classes of REGULAR and, under different conditions, CONTEXT-SENSITIVE as well as PSPACE paraconsistent relations are such. We also show that the CONTEXT-FREE and R.E. classes do not have the desired properties, while P, NP, LOGSPACE and NLOGSPACE also probably do not. These results help identify the kinds of relational DBMS that can be constructed for handling incomplete and inconsistent information about tuples. We finally show that all operations for the aforementioned PSPACE and CONTEXT-SENSITIVE cases can be carried out efficiently in polynomial time.     

Hemagglutinin-neuraminidase enhances F protein-mediated membrane fusion of reconstituted Sendai virus envelopes with cells

Reconstituted Sendai virus envelopes containing both the fusion (F) protein and the hemagglutinin-neuraminidase (HN) (F,HN-virosomes) or only the F protein (F-virosomes) were prepared by solubilization of the intact virus with Triton X-100 followed by its removal by using SM2 Bio-Beads. Viral envelopes containing HN whose disulfide bonds were irreversibly reduced (HNred) were also prepared by treating the envelopes with dithiothreitol followed by dialysis (F,HNred-virosomes). Both F-virosomes and F,HNred-virosomes induced hemolysis of erythrocytes in the presence of wheat germ agglutinin, but the rates and extents were markedly lower than those for hemolysis induced by F,HN-virosomes. Using an assay based on the relief of self-quenching of a lipid probe incorporated in the Sendai virus envelopes, we demonstrate the fusion of both F,HN-virosomes and F-virosomes with cultured HepG2 cells containing the asialoglycoprotein receptor, which binds to a terminal galactose moiety of F. By desialylating the HepG2 cells, the entry mediated by HN-terminal sialic acid receptor interactions was bypassed. We show that both F-virosomes and F,HN-virosomes fuse with desialylated HepG2 cells, although the rate was two- to threefold higher if HN was included in the viral envelope. We also observed enhancement of fusion rates when both F and HN envelope proteins were attached to their specific receptors.     

Theory of te precipitation and related effects in CdTe Crystals

A thermodynamic calculation is presented which explains the origin of often reported large stress fields in and around Te precipitates and associated punching of dislocation loops in star like patterns. The calculation is based on the consideration that the stoichiometric deviation in Te saturated crystals are accommodated by Te interstitials, Cd multivacancy complexes and Te antisites; the Te interstitials are most mobile of them, and dominate the precipitation process; and the precipitates when they appear first are in droplet form. The droplet state is modelled on the basis of the Lennard-Jones 6-12 interaction potential. The droplet growth is envisaged to occur via the following two processes operating in tandem: first, capture of excess Te interstitials to cause droplet overpressurization, and then, punching of interstitial dislocation loops whenever the pressure exceeds a threshold value. The flow of Te interstitials into the droplets is driven by the difference between their formation energies in the lattice and the free energy change of the droplets per Te atom added. It is shown that the achievable droplet pressures far exceed that required for the loop punching and sustaining the growth cycle. The occurrence of varying precipitate morphologies are explained, and the possibility of nucleating high presssure Te phases is examined. Some experimental evidence is also presented which corroborate the theoretical arguments involved.     

Palmitylation of the influenza virus hemagglutinin (H3) is not essential for virus assembly or infectivity

The C terminus of the influenza virus hemagglutinin (HA) contains three cysteine residues that are highly conserved among HA subtypes, two in the cytoplasmic tail and one in the transmembrane domain. All of these C-terminal cysteine residues are modified by the covalent addition of palmitic acid through a thio-ether linkage. To investigate the role of HA palmitylation in virus assembly, we used reverse genetics technique to introduce substitutions and deletions that affected the three conserved cysteine residues into the H3 subtype HA. The rescued viruses contained the HA of subtype H3 (A/Udorn/72) in a subtype H1 helper virus (A/WSN/33) background. Rescued viruses which do not contain a site for palmitylation (by residue substitution or substitution combined with deletion of the cytoplasmic tail) were obtained. Rescued virions had a normal polypeptide composition. Analysis of the kinetics of HA low-pH-induced fusion of the mutants showed no major change from that of virus with wild-type (wt) HA. The PFU/HA ratio of the rescued viruses grown in eggs ranged from that of virus with wt HA to 16-fold lower levels, whereas the PFU/HA ratio of the rescued viruses grown in MDCK cells varied only 2-fold from that of virus with wt HA. However, except for one rescued mutant virus (CAC), the mutant viruses were attenuated in mice, as indicated by a > or = 400-fold increase in the 50% lethal dose. Interestingly, except for one mutant virus (CAC), all of the rescued mutant viruses were restricted for replication in the upper respiratory tract but much less restricted in the lungs. Thus, the HA cytoplasmic tail may play a very important role in the generation of virus that can replicate in multiple cell types.     

Precipitation in CdTe crystals studied through mie scattering

Below gap optical losses in as-grown n-type CdTe crystals were analyzed in terms of free carrier absorption and Mie extinction due to Te precipitates. Experimental absorption spectra measured between 2 to 20 μm exhibited the well-known free carrier absorption behavior α_FCA∼λ^x with x=3 due to scattering by polar optical phonons. In shorter wavelength regions below 6 μm, however, additional contributions to the light loss due to absorption and scattering by precipitates were also observed. Assuming a log-normal size distribution, the precipitate extinction spectra were calculated according to Mie theory within the electric and magnetic dipole and electric quadrupole approximation. A comparison with the experimental spectra identifies the precipitates and enables estimation of their sizes and total number density. In this investigation, both undoped and In-doped CdTe crystals grown from stoichiometric melts by vertical asymmetric Bridgman method were used. It was found that In doping, in general, suppresses Te precipitation. At high doping level (melt containing∼10¹⁹ In atoms cm⁻³), the formation of In₂Te₂ is also indicated. It is demonstrated that the Mie extinction analysis offers an, expedient method to rapidly analyze the precipitates in CdTe and in similar other wide gap materials in a nondestructive manner.     

Heat and mass transfer under MHD mixed convection in a four-sided lid-driven square cavity

This paper investigates the heat and mass transfer under magnetohydrodynamic mixed convection flow of a binary gas mixture in a four-sided lid-driven square cavity. The enclosure's left wall is sinusoidally heated and acts as a source term, while the right wall functions as a sink. The cavity's horizontal walls are adiabatic and impermeable to mass transfer. The governing equations under Boussinesq approximation and stream function-vorticity formulation are solved using the alternating-direction-implicit scheme, a finite-difference method. The numerical scheme's consistency and stability are demonstrated using the matrix method. The MATLAB code is written, validated against some existing studies, and used to perform numerical simulations. The numerical solutions are graphically examined by visualizing the streamline, isotherm, and concentration contours for nondimensional parameters, such as Hartmann number $\left(0\le Ha\le 100\right)$, heat absorption or generation coefficient $\left(-2\le \varphi \le 2\right)$, Richardson number $\left(0.01\le Ri\le 100\right)$, and buoyancy ratio $\left(-6\le N\le 6\right)$. The magnetic field modifies the temperature and concentration distribution in the cavity, depending on the convection mode. The magnetic field forces the fluid to stagnate in different regions of the cavity, depending on the mode of convection. It was found that the difference between the maximum and minimum temperature and concentration at the cavity's midpoint increases up to 13 and 10 times, respectively, in the natural convection compared with the forced convection. The average Nusselt number on the vertical walls of the cavity is maximum in natural convection in the absence of a magnetic field but reaches a minimum value at $Ha=100$ in forced and mixed convection. The average Sherwood number on the cavity's vertical walls decreases with the magnetic field in mixed and natural convection.