1,877 research outputs found
Binding of Basic Dyes by the Algae, Chara aspera
Non-living biomass of the algae Chara aspera is capable of binding two basic dyes, methylene blue and basic blue 3, from aqueous solution. Factors such as dye concentration, contact time, sorbent dosage and pH of solution were
studied. Maximum sorption capacities of the algae for methylene blue and basic blue 3 are 139.4 and 17.8 mg/g, respectively, as determined from the
Langmuir isothenns
Circular tests for HSM machine tools: Bore machining application
Today's High-Speed Machining (HSM) machine tool combines productivity and
part quality. The difficulty inherent in HSM operations lies in understanding
the impact of machine tool behaviour on machining time and part quality.
Analysis of some of the relevant ISO standards (230-1998, 10791-1998) and a
complementary protocol for better understanding HSM technology are presented in
the first part of this paper. These ISO standards are devoted to the procedures
implemented in order to study the behavior of machine tool. As these procedures
do not integrate HSM technology, the need for HSM machine tool tests becomes
critical to improving the trade-off between machining time and part quality. A
new protocol for analysing the HSM technology impact during circular
interpolation is presented in the second part of the paper. This protocol which
allows evaluating kinematic machine tool behaviour during circular
interpolation was designed from tests without machining. These tests are
discussed and their results analysed in the paper. During the circular
interpolation, axis capacities (such as acceleration or Jerk) related to
certain setting parameters of the numerical control unit have a significant
impact on the value of the feed rate. Consequently, a kinematic model for a
circular-interpolated trajectory was developed on the basis of these
parameters. Moreover, the link between part accuracy and kinematic machine tool
behaviour was established. The kinematic model was ultimately validated on a
bore machining simulation
Role of Interleukin 17 in arthritis chronicity through survival of synoviocytes via regulation of synoviolin expression
Background:
The use of TNF inhibitors has been a major progress in the treatment of chronic inflammation. However, not all patients respond. In addition, response will be often lost when treatment is stopped. These clinical aspects indicate that other cytokines might be involved and we focus here on the role of IL-17. In addition, the chronic nature of joint inflammation may contribute to reduced response and enhanced chronicity. Therefore we studied the capacity of IL-17 to regulate synoviolin, an E3 ubiquitin ligase implicated in synovial hyperplasia in human rheumatoid arthritis (RA) FLS and in chronic reactivated streptococcal cell wall (SCW)-induced arthritis.<p></p>
Methodology/Principal Findings:
Chronic reactivated SCW-induced arthritis was examined in IL-17R deficient and wild-type mice. Synoviolin expression was analysed by real-time RT-PCR, Western Blot or immunostaining in RA FLS and tissue, and p53 assessed by Western Blot. Apoptosis was detected by annexin V/propidium iodide staining, SS DNA apoptosis ELISA kit or TUNEL staining and proliferation by PCNA staining. IL-17 receptor A (IL-17RA), IL-17 receptor C (IL-17-RC) or synoviolin inhibition were achieved by small interfering RNA (siRNA) or neutralizing antibodies. IL-17 induced sustained synoviolin expression in RA FLS. Sodium nitroprusside (SNP)-induced RA FLS apoptosis was associated with reduced synoviolin expression and was rescued by IL-17 treatment with a corresponding increase in synoviolin expression. IL-17RC or IL-17RA RNA interference increased SNP-induced apoptosis, and decreased IL-17-induced synoviolin. IL-17 rescued RA FLS from apoptosis induced by synoviolin knockdown. IL-17 and TNF had additive effects on synoviolin expression and protection against apoptosis induced by synoviolin knowndown. In IL-17R deficient mice, a decrease in arthritis severity was characterized by increased synovial apoptosis, reduced proliferation and a marked reduction in synoviolin expression. A distinct absence of synoviolin expressing germinal centres in IL-17R deficient mice contrasted with synoviolin positive B cells and Th17 cells in synovial germinal centre-like structures.<p></p>
Conclusion/Significance:
IL-17 induction of synoviolin may contribute at least in part to RA chronicity by prolonging the survival of RA FLS and immune cells in germinal centre reactions. These results extend the role of IL-17 to synovial hyperplasia.<p></p>
Molecular dynamics simulations of lead clusters
Molecular dynamics simulations of nanometer-sized lead clusters have been
performed using the Lim, Ong and Ercolessi glue potential (Surf. Sci. {\bf
269/270}, 1109 (1992)). The binding energies of clusters forming crystalline
(fcc), decahedron and icosahedron structures are compared, showing that fcc
cuboctahedra are the most energetically favoured of these polyhedral model
structures. However, simulations of the freezing of liquid droplets produced a
characteristic form of ``shaved'' icosahedron, in which atoms are absent at the
edges and apexes of the polyhedron. This arrangement is energetically favoured
for 600-4000 atom clusters. Larger clusters favour crystalline structures.
Indeed, simulated freezing of a 6525-atom liquid droplet produced an imperfect
fcc Wulff particle, containing a number of parallel stacking faults. The
effects of temperature on the preferred structure of crystalline clusters below
the melting point have been considered. The implications of these results for
the interpretation of experimental data is discussed.Comment: 11 pages, 18 figues, new section added and one figure added, other
minor changes for publicatio
Surface-reconstructed Icosahedral Structures for Lead Clusters
We describe a new family of icosahedral structures for lead clusters. In
general, structures in this family contain a Mackay icosahedral core with a
reconstructed two-shell outer-layer. This family includes the anti-Mackay
icosahedra, which have have a Mackay icosahedral core but with most of the
surface atoms in hexagonal close-packed positions. Using a many-body glue
potential for lead, we identify two icosahedral structures in this family which
have the lowest energies of any known structure in the size range from 900 to
15000 lead atoms. We show that these structures are stabilized by a feature of
the many-body glue part of the interatomic potential.Comment: 9 pages, 8 figure
Stabilized Kuramoto-Sivashinsky system
A model consisting of a mixed Kuramoto - Sivashinsky - KdV equation, linearly
coupled to an extra linear dissipative equation, is proposed. The model applies
to the description of surface waves on multilayered liquid films. The extra
equation makes its possible to stabilize the zero solution in the model,
opening way to the existence of stable solitary pulses (SPs). Treating the
dissipation and instability-generating gain in the model as small
perturbations, we demonstrate that balance between them selects two
steady-state solitons from their continuous family existing in the absence of
the dissipation and gain. The may be stable, provided that the zero solution is
stable. The prediction is completely confirmed by direct simulations. If the
integration domain is not very large, some pulses are stable even when the zero
background is unstable. Stable bound states of two and three pulses are found
too. The work was supported, in a part, by a joint grant from the Israeli
Minsitry of Science and Technology and Japan Society for Promotion of Science.Comment: A text file in the latex format and 20 eps files with figures.
Physical Review E, in pres
Premelting of Thin Wires
Recent work has raised considerable interest on the nature of thin metallic
wires. We have investigated the melting behavior of thin cylindrical Pb wires
with the axis along a (110) direction, using molecular dynamics and a
well-tested many-body potential. We find that---in analogy with cluster
melting---the melting temperature of a wire with radius is lower
than that of a bulk solid, , by . Surface melting
effects, with formation of a thin skin of highly diffusive atoms at the wire
surface, is observed. The diffusivity is lower where the wire surface has a
flat, local (111) orientation, and higher at (110) and (100) rounded areas. The
possible relevance to recent results on non-rupturing thin necks between an STM
tip and a warm surface is addressed.Comment: 10 pages, 4 postscript figures are appended, RevTeX, SISSA Ref.
131/94/CM/S
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Evaluation of the Serotonergic Genes htr1A, htr1B, htr2A, and slc6A4 in Aggressive Behavior of Golden Retriever Dogs
Aggressive behavior displays a high heritability in our study group of Golden Retriever dogs. Alterations in brain serotonin metabolism have been described in aggressive dogs before. Here, we evaluate whether four genes of the canine serotonergic system, coding for the serotonin receptors 1A, 1B, and 2A, and the serotonin transporter, could play a major role in aggression in Golden Retrievers. We performed mutation screens, linkage analysis, an association study, and a quantitative genetic analysis. There was no systematic difference between the coding DNA sequence of the candidate genes in aggressive and non-aggressive Golden Retrievers. An affecteds-only parametric linkage analysis revealed no strong major locus effect on human-directed aggression related to the candidate genes. An analysis of 41 single nucleotide polymorphisms (SNPs) in the 1Â Mb regions flanking the genes in 49 unrelated human-directed aggressive and 49 unrelated non-aggressive dogs did not show association of SNP alleles, genotypes, or haplotypes with aggression at the candidate loci. We completed our analyses with a study of the effect of variation in the candidate genes on a collection of aggression-related phenotypic measures. The effects of the candidate gene haplotypes were estimated using the Restricted Maximum Likelihood method, with the haplotypes included as fixed effects in a linear animal model. We observed no effect of the candidate gene haplotypes on a range of aggression-related phenotypes, thus extending our conclusions to several types of aggressive behavior. We conclude that it is unlikely that these genes play a major role in the variation in aggression in the Golden Retrievers that we studied. Smaller phenotypic effects of these loci could not be ruled out with our sample size.Organismic and Evolutionary Biolog
A Simple Model for Anisotropic Step Growth
We consider a simple model for the growth of isolated steps on a vicinal
crystal surface. It incorporates diffusion and drift of adatoms on the terrace,
and strong step and kink edge barriers. Using a combination of analytic methods
and Monte Carlo simulations, we study the morphology of growing steps in
detail. In particular, under typical Molecular Beam Epitaxy conditions the step
morphology is linearly unstable in the model and develops fingers separated by
deep cracks. The vertical roughness of the step grows linearly in time, while
horizontally the fingers coarsen proportional to . We develop scaling
arguments to study the saturation of the ledge morphology for a finite width
and length of the terrace.Comment: 20 pages, 12 figures; [email protected]
Projection methods in conic optimization
There exist efficient algorithms to project a point onto the intersection of
a convex cone and an affine subspace. Those conic projections are in turn the
work-horse of a range of algorithms in conic optimization, having a variety of
applications in science, finance and engineering. This chapter reviews some of
these algorithms, emphasizing the so-called regularization algorithms for
linear conic optimization, and applications in polynomial optimization. This is
a presentation of the material of several recent research articles; we aim here
at clarifying the ideas, presenting them in a general framework, and pointing
out important techniques
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