Compliance of rough cylinders in compression

Compression of a rough turned cylinder between two hard, smooth, flat plates has been analysed with the aid of a mathematical model based on statistical analysis. It is assumed that the asperity peak heights follow Gaussian or normal and beta distribution functions and that the loaded asperities comply as though they are completely isolated from the neighbouring ones. Equations have been developed for the loadcompliance relation of the real surface using a simplified relation of the form W0 = K1δn for the load-compliance of a single asperity. Parameters K1 and n have considerable influence on the load-compliance curve and they depend on the material, tip angle of the asperity, standard deviation of the asperity peak height distribution and the density of the asperities.

EESM-Based Link Adaptation in Point-to-Point and Multi-Cell OFDM Systems: Modeling and Analysis

In contemporary wideband orthogonal frequency division multiplexing (OFDM) systems, such as Long Term Evolution (LTE) and WiMAX, different subcarriers over which a codeword is transmitted may experience different signal-to-noise-ratios (SNRs). Thus, adaptive modulation and coding (AMC) in these systems is driven by a vector of subcarrier SNRs experienced by the codeword, and is more involved. Exponential effective SNR mapping (EESM) simplifies the problem by mapping this vector into a single equivalent fiat-fading SNR. Analysis of AMC using EESM is challenging owing to its non-linear nature and its dependence on the modulation and coding scheme. We first propose a novel statistical model for the EESM, which is based on the Beta distribution. It is motivated by the central limit approximation for random variables with a finite support. It is simpler and as accurate as the more involved ad hoc models proposed earlier. Using it, we develop novel expressions for the throughput of a point-to-point OFDM link with multi-antenna diversity that uses EESM for AMC. We then analyze a general, multi-cell OFDM deployment with co-channel interference for various frequency-domain schedulers. Extensive results based on LTE and WiMAX are presented to verify the model and analysis, and gain new insights.

Factors affecting the synthesis and distribution of beta-lactamase in Mycobacterium smegmatis SN2 cultures

A high level of extracellular beta-lactamase activity was detected in cultures ofMycobacterium smegmatis SN2. The extracellular distribution of the enzyme varied with growth conditions such as additional carbon source and pH of the medium. Addition of chloramphenicol tothe culture inhibited the increase in the extracellular beta-lactamase activity. Cell wall damage or autolysis may be responsible for the extracellular beta-lactamase activity.

On variant distribution and coarsening behavior of the a phase in a metastable beta titanium alloy

The stereology, variant distribution and coarsening behavior of semicoherent alpha(hcp) precipitates in a beta(bcc) matrix of a Ti5553 alloy has been analyzed, and a dominant 3-variant cluster has been observed in which the variants are related to each other by an axis-angle pair <<11(2)over bar> 0 >/60 degrees. Shape and spatial distribution independent elastic self and interaction energies for all pairwise and triplet combinations of a have been calculated and it is found that the 3-cluster combination that is experimentally observed most frequently has the lowest energy for the semicoherent state. The coarsening behavior of the delta distribution follows LSW kinetics after an initial transient, and has been modeled by phase field methods. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Continuous Distribution Kinetics for Photopolymerization of Alkyl Methacrylates

The photopolymerization of methyl,ethyl,butyl, and hexyl methacrylates in solution was studied. The effect of initial initiator and monomer concentrations on the time evolution of polymer concentration (M) over bar (n) and PDI was examined. The reversible chain addition and beta-scission, and primary radical termination steps were included in the mechanism along with the classical steps. The rate equations were derived using continuous distribution kinetics and solved numerically to fit the experimental data. The regressed rate coefficients compared well with the literature data. The model predicted the instantaneous increase in (M) over bar (n) and PDI to steady state values. The rate coefficients exhibited a linear increase with the size of alkyl chain of the alkyl methacrylates.

Identification of alpha- and beta-Hydroxy Acid Containing Cyclodepsipeptides in Natural Peptide Mixtures Using Negative Ion Mass Spectrometry

Natural peptide libraries often contain cyclodepsipeptides containing alpha or beta hydroxy residues. Extracts of fungal hyphae of Isaria yield a microheterogenous cyclodepsipeptide mixture in which two classes of molecules can be identified by mass spectral fragmentation of negative ions. In the case of isaridins, which contain an alpha-hydroxy residue and a beta-amino acid residue, a characteristic product ion corresponding to a neutral loss of 72 Da is obtained. hi addition, neutral loss of water followed by a 72 Da loss is also observed. Two distinct modes of fragmentation rationalize the observed product ion distribution. The neutral loss of 72 Da has also been obtained for a roseotoxin component, which is also an alpha-hydroxy residue containing cyclodepsipeptide. In the case of isariins, which contain a beta-hydroxy acid residue, ring opening and subsequent loss of the terminal residue as an unsaturated ketene fragment, rationalizes the observed product ion formation. Fragmentation of negative ions provide characteristic neutral losses, which are diagnostic of the presence of alpha-hydroxy or beta-hydroxy residues.

Effect of mode of rolling on development of texture and microstructure in two-phase (alpha plus beta) brass

The evolution of microstructure and texture during deformation of two-phase (alpha + beta) brass was studied for different initial microstructure and texture. The deformation processing involved unidirectional and multi-step cross-rolling. The bulk textures were determined by measuring the pole figures and calculating the orientation distribution function ODF for both alpha (fcc) and beta (bcc) phases, while the microstructure and other microstructural parameters were measured through optical microscopy and scanning electron microscopy with electron back scatter diffraction (SEM-EBSD). Results indicate that textures developed after unidirectional rolling and multi-step cross-rolling are significantly different. The variation in initial texture had a pronounced effect on the development of texture in the alpha phase during subsequent deformation. (C) 2010 Elsevier B.V. All rights reserved.

Chain Length Effects on Helix-Hairpin Distribution in Short Peptides with Aib-(D)Ala and Aib-Aib Segments

The Aib-(D)Ala dipeptide segment has a tendency to form both type-I'/III' and type-I/III beta-turns. The occurrence of prime turns facilitates the formation of beta-hairpin conformations, while type-I/III turns can nucleate helix formation. The octapeptide Boc-Leu-Phe-Val-Aib-(D)Ala-Leu-Phe-Val-OMe (1) has been previously shown to form a beta-hairpin in the crystalline state and in solution. The effects of sequence truncation have been examined using the model peptides Boc-Phe-Val-Aib-Xxx-Leu-Phe-NHMe (2, 6), Boc-Val-Aib-Xxx-Leu-NHMe (3, 7), and Boc-Aib-Xxx-NHMe (4, 8), where Xxx = (D)Ala, Aib. For peptides with central Aib-Aib segments, Boc-Phe-Val-Aib-Aib-Leu-Phe-NHMe (6), Boc-Val-Aib-Aib-Leu-NHMe (7), and Boc-Aib-Aib-NHMe (8) helical conformations have been established by NMR studies in both hydrogen bonding (CD(3)OH) and non-hydrogen bonding (CDCl(3)) solvents. In contrast, the corresponding hexapeptide Boc-Phe-Val-Aib-(D)Ala-Leu-Phe-Val-NHMe (2) favors helical conformations in CDCl(3) and beta-hairpin conformations in CD(3)OH. The beta-turn conformations (type-I'/III) stabilized by intramolecular 4 -> 1 hydrogen bonds are observed for the peptide Boc-Aib-(D)Ala-NHMe (4) and Boc-Aib-Aib-NIiMe (8) in crystals. The tetrapeptide Boc-Val-Aib-Aib-Leu-NHMe (7) adopts an incipient 3(10)-helical conformation stabilized by three 4 -> 1 hydrogen bonds. The peptide Boc-Val-Aib-(D)Ala-Leu-NHMe (3) adopts a novel et-turn conformation, stabilized by three intramolecular hydrogen bonds (two 4 -> 1 and one 5 -> 1). The Aib-L(D)Ala segment adopts a type-I' beta-turn conformation. The observation of an NOE between Val (1) NH <-> HNCH(3) (5) in CD(3)OH suggests, that the solid state conformation is maintained in methanol solutions. (C) 2011 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 744-756, 2011.

Study of molecular structure and vibrational spectra of poly (beta,-1-malic acid) PMLA] using DFT approach

Poly (beta-L-malic acid) (PMLA) is a biodegradable polymer and it has various important applications in the biomedical field. In the present work the structural and spectral characteristics of PMLA have been studied by methods of infrared. Raman spectroscopy and quantum chemistry. Electrostatic potential surface, optimized geometry, harmonic vibrational frequencies, infrared intensities and activities of Raman scattering were calculated by density functional theory (DFT) using oligomeric approach employing B3LYP with complete relaxation in the potential energy surface using 6-311++G (d, p) basis set. Based on results, we have discussed the correlation between the vibrational modes and the structure of the PMLA. A complete analysis of the experimental infrared and Raman spectra has been reported on the basis of wavenumber of the vibrational bands and potential energy distribution. The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The calculated infrared and the Raman spectra of the polymer based on DFT calculations show reasonable agreement with the experimental results. (c) 2012 Elsevier Ltd. All rights reserved.

Enhanced superplasticity for (alpha plus beta)-hot rolled Ti-6Al-4V-0.1B alloy by means of dynamic globularization

Thermo-mechanically processed Ti-6Al-4V alloy, with (0.1 wt.%) and without boron addition, has been subjected to tensile test under superplastic deformation conditions (Temperature, T = 850 degrees C and initial strain rate, (epsilon) over dot = 3 x 10(-4) s(-1)). The boron added alloy exhibited higher elongation (similar to 430%) in comparison to the base alloy without boron (similar to 365%). Superior ductility of the boron added alloy has been attributed to an enhanced alpha/beta interfacial boundary sliding. This was caused by riotous dynamic globularization leading to the abundant presence of equiaxed primary alpha grains with refined sizes and narrow distribution in the deforming microstructure. Cavities do occur around TiB particles during deformation; the cavities are, however, extremely localized and do not cause macroscopic cracking. (C) 2014 Elsevier Ltd. All rights reserved.

Thermal conductivity of beta-FeSi2/Si endogenous composites formed by the eutectoid decomposition of alpha-Fe2Si5

Thermoelectric properties of semiconducting beta-FeSi2 containing a homogeneous distribution of Si secondary phase have been studied. The synthesis was carried out using arc melting followed by the densification by uniaxial hot pressing. Endogenous beta-FeSi2/Si composites were produced by the eutectoid decomposition of high-temperature alpha-Fe2Si5 phase. The aging heat treatments have been carried out at various temperatures below the equilibrium eutectoid temperature for various durations in order to tune the size of the eutectoid product. Thermal properties of the samples were studied in the temperature range of 100-350 A degrees C. The microstructural investigations support the fact that the finest microstructure generated through the eutectoid decomposition of the alpha-Fe2Si5 metastable phase is responsible of the phonon scattering. The results suggest an opportunity to produce bulk iron silicide alloys with reduced thermal conductivity in order to enhance its thermoelectric performance.

A new load distribution strategy for linear network with communication delays

In this paper, we propose a new load distribution strategy called `send-and-receive' for scheduling divisible loads, in a linear network of processors with communication delay. This strategy is designed to optimally utilize the network resources and thereby minimizes the processing time of entire processing load. A closed-form expression for optimal size of load fractions and processing time are derived when the processing load originates at processor located in boundary and interior of the network. A condition on processor and link speed is also derived to ensure that the processors are continuously engaged in load distributions. This paper also presents a parallel implementation of `digital watermarking problem' on a personal computer-based Pentium Linear Network (PLN) topology. Experiments are carried out to study the performance of the proposed strategy and results are compared with other strategies found in literature.

Beta-Turn Conformations In Crystal-Structures Of Model Peptides Containing Alpha,Alpha-Di-N-Propylglycine And Alpha,Alpha-Di-N-Butylglycine

The crystal state conformations of three peptides containing the alpha, alpha-dialkylated residues, alpha,alpha-di-n-propylglycine (Dpg) and alpha,alpha-di-n-butylglycine (Dbg), have been established by x-ray diffraction. Boc-Ala-Dpg-Ala-OMe (I) and Boc-Ala-Dbg-Ala-OMe (III) adopt distorted type II beta-turn conformations with Ala (1) and Dpg/Dbg (2) as the corner residues. In both peptides the conformational angles at the Dxg residue (I: phi = 66.2 degrees, psi = 19.3 degrees; III: phi = 66.5 degrees, psi = 21.1 degrees) deviate appreciably from ideal values for the i + 2 residue in a type II beta-turn. In both peptides the observed (N...O) distances between the Boc CO and Ala(3) NH groups are far too long (I: 3.44 Angstrom; III: 3.63 Angstrom) for an intramolecular 4 --> 1 hydrogen bond. Boc-Ala-Dpg-Ala-NHMe (II) crystallizes with two independent molecules in the asymmetric unit. Both molecules IIA and IIB adopt consecutive beta-turn (type III-III in IIA and type III-I in IIB) or incipient 3(10)-helical structures, stabilized by two intramolecular 4 --> 1 hydrogen bonds. In all four molecules the bond angle N-C-alpha-C' (tau) at the Dxg residues are greater than or equal to 110 degrees. The observation of conformational angles in the helical region of phi,psi space at these residues is consistent with theoretical predictions.

An Efficient Load Distribution Strategy for a Distributed Linear Network of Processors with Communication Delays

In this paper, we present an improved load distribution strategy, for arbitrarily divisible processing loads, to minimize the processing time in a distributed linear network of communicating processors by an efficient utilization of their front-ends. Closed-form solutions are derived, with the processing load originating at the boundary and at the interior of the network, under some important conditions on the arrangement of processors and links in the network. Asymptotic analysis is carried out to explore the ultimate performance limits of such networks. Two important theorems are stated regarding the optimal load sequence and the optimal load origination point. Comparative study of this new strategy with an earlier strategy is also presented.

Identification of actin as an estradiol 17-beta-stimulated protein in the human placenta

Addition of estradiol 17-beta to first trimester human placental minces resulted in an increased synthesis of a protein of apparent molecular weight 45 kDa. The specific involvement of estrogen in the stimulation of this protein was established by demonstrating a reduction in the level of this protein by the addition of CCS 16949 A, an inhibitor of aromatase, a key enzyme in the biosynthesis of estradiol 17-beta and ICI 182,780, an estrogen receptor antagonist. The protein was purified to homogeneity and N-terminal sequencing of two of the internal peptides obtained by enzymatic digestion of the protein, as well as the absence of a free N-terminal indicated that it could be actin. This was confirmed by Western blotting using commercially available actin antiserum. The role of estradiol 17-beta in the stimulation of actin synthesis in human placenta was also established by monitoring the quantitative inhibition of DNase I by actin.