Determination of isoclinics in photoelasticity with a fast regularized estimator

The determination of isoclinics from photoelastic fringe patterns is a key problem in photoelasticity. Dealing with this problem, however, is not a simple task when isotropic points are present which is common for most experimental situations. Because of this, few researchers have proposed effective and practical solutions. Visualizing this problem as the problem of the determination of the modulo 2π fringe orientation, in this paper it is proposed an efficient regularized algorithm to solve it. Experimental results show that the proposal is effective and can be used with either monochromatic or white light.     

The Role of the Pars Recta and Pars Oblique of Cricothyroid Muscle in Speech Production

To evaluate the functional difference of the pars recta and pars oblique during speech production, the electromyographic activities of these muscles were measured in thyroidectomized patients. The hooked wire electrodes were inserted into the normal side of the bellies of the pars recta and pars oblique bundles. Two kinds of sentences were used to obtain pitch changes, a simple interrogative sentence and a complex sentence with stress contrasts. The pars recta and pars oblique were simultaneously activated for initial lengthening and tensing of vocal folds to produce speech. The pars oblique might be initially more active than the pars recta at the initial task of speech and the pars recta might be more active at the pitch elevation in the interrogative sentence and the stress contrast of the complex sentence. The maximum electromyographic activity range of the pars recta and pars oblique seemed to be nearly equal. These results demonstrated that the patterns of electrical activities of the two bellies are different during speech and the combined activities of the pars recta and pars oblique are important in the adjustment of the vocal fold length during speech.     

Critical dimension for a system of partial differential equations with time‐dependent generators

We give sufficient conditions for blows up of positive mild solutions for the weakly coupled system: where is a fractional Laplacian, 0 < α_i≤2,β_i≥1,ρ_i>0,σ_i>?1 are constants, and the initial condition ?_i are positive, bounded and integrable functions. We also discuss the critical dimension. Copyright © 2014 John Wiley & Sons, Ltd.     

LptA Assembles into Rod-Like Oligomers Involving Disorder-to-Order Transitions

LptA is a periplasmic protein involved in the transport of lipopolysaccharide (LPS) from the inner membrane (IM) to the outer membrane (OM) of Gram-negative bacteria. Growing evidence supports a model in which LptA assembles into oligomers, forming a physical bridge connecting IM and OM. This work investigates assembly and architecture of LptA oligomers. Circular dichroism and “native” electrospray-ionization ion-mobility mass spectrometry (ESI-IM-MS) are employed to test concentration dependence of LptA structural features and to analyze the morphology of higher-order aggregates. The results show that LptA progressively assembles into rod-like oligomers without fixed stoichiometry, and grows by an n + 1 mechanism up to at least the pentamer. The oligomerization process induces disorder-to-order transitions in the polypeptide chain. Comparison with crystallographic and computational data suggests that these conformational changes likely involve short disordered regions at the N- and C-termini of monomeric LptA. The protein response to thermal denaturation displays strong concentration dependence, indicating that oligomerization increases protein stability. LptA conformational stability can also be enhanced by in vitro LPS binding. The genesis of these fibrillar structures could be relevant for the correct transport of LPS across the bacterial periplasm.      

Research reactors as sources of atmospheric radioxenon

Radioxenon emissions of the TRIGA Mark II research reactor in Vienna were investigated with respect to a possible impact on the verification of the Comprehensive Nuclear Test-Ban-Treaty. Using the Swedish Automatic Unit for Noble Gas Acquisition (SAUNA II), five radioxenon isotopes ¹²⁵Xe, ^131mXe, ^133mXe, ¹³³Xe and ¹³⁵Xe were detected, of which ¹²⁵Xe is solely produced by neutron capture in stable atmospheric ¹²⁴Xe and hence acts as an indicator for neutron activation processes. The other nuclides are produced in both fission and neutron capture reactions. The detected activity concentrations ranged from 0.0010 to 190 Bq/m³. The source of the radioxenon is not yet fully clarified, but it could be micro-cracks in the fuel cladding, fission of ²³⁵U contaminations on the outside of the fuel elements or neutron activation of atmospheric Xe. Neutron deficient ¹²⁵Xe with its highly complex decay scheme was seen for the first time in a SAUNA system. In many experiments the activity ratios of the radioxenon nuclides carry the signature of nuclear explosions, if ^131mXe is omitted. Only if ^131mXe is included into the calculations of the isotopic activity ratios, the majority of the measurements revealed a “civil” signature (typical for a NPP). A significant contribution of the TRIGA Vienna to the global or European radioxenon inventory can be excluded. Due to the very low activities, the emissions are far below any concern for human health.     

Crystal and molecular structures of the orthorhombic and monoclinic isomers of catena-di-μ-chloro-semicarbazidecopper(II)

The crystal structures of two isomeric complex compounds of formula [Cu(Cl)₂(NH₂NHCONH₂)] have been determined by X-ray diffraction methods. The orthorhombic isomer has space groupPna2₁ and unit cell constants:a = 6·91(1),b = 8·30(1),c = 10·24(1) Å;Z = 4. The monoclinic isomer has space groupP2₁/c and unit cell constants:a = 6·91(1),b = 8·30(1),c = 11·32(1) Å, = 117·1(2)°;Z = 4. In both complexes coordination around copper is octahedral, with chains of coordination polyhedra along [100]. In the monoclinic compound, the two semicarbazide molecules, which are present in two adjacent octahedra along the chain, have the oxygen and nitrogen atoms in thetrans configuration, one with respect to the other, and are correlated by a centre of symmetry. In the orthorhombic compound, the two semicarbazide molecules are in thecis configuration and there is no centre of symmetry. In both compounds packing is determined by the NH···Cl and NH···O hydrogen bonds which join the chains together.The authors are indebted to Mr M. Lanfranchi who prepared the compounds and to Dr A. Immirzi who made abailable his computer programs.     

Synthesis, characterization and reactivity studies of the new compound [Os3(CO)9(μ3-η,η,η-{C5H5FeC5H3CCC(S)C(Fc)CHO}]

Processes such as S-C and C-H bond activations as well as C-C coupling reactions have taken place in the synthesis of the new compound [Os₃(CO)₉(μ₃-η²,η³,η³-{C₅H₅FeC₅H₃CCC(S)C(Fc)CHO}] (Fc = C₅H₄FeC₅H₅), which contains an aldehyde oxametallacycle. A reactivity study of it has been carried out. In addition, other new triosmium clusters such as [Os₃(CO)₉(μ₃,η²-CCFc)(μ,η¹-SCCFc)], [Os₃(CO)₁₀(μ,η²-CCFc)(μ,η¹-SCCFc)] and [Os₃(CO)₉(μ-CO)(μ₃,η²-FcCCSCCFc)] have been prepared from the reaction of [Os₃(CO)₁₀(NCMe)₂] and FcCCSCCFc. All the compounds have been characterized by analytical and spectroscopic techniques. The crystal structures of [Os₃(CO)₉(μ₃,η²-CCFc)(μ,η¹-SCCFc)] and [Os₃(CO)₉(μ₃-η²,η³,η³-{C₅H₅FeC₅H₃CCC(S)C(Fc)CHO}] have been determined by X-ray crystallography and some electrochemical studies have also carried out.     

Accumulation of arsenic(III) by chlorella vulgaris

Arsenic occurs naturally in the environment and also through agricultural and industrial pollution. Since arsenic species show different toxicities, it is important to be able to separate them. Methods using microorganisms are being applied increasingly to remove metal ions and different metal species from aqueous solutions. Accumulation of As(III) by Chlorella vulgaris algae was studied, including various factors that influence on accumulation capacity, e.g. pretreatment of the algae (live, dry and lyophilized algae), temperature (4, 22, 37 and 100 °C), pH and exposure time of the algae to arsenic solutions. The pH appears to be the most critical factor, probably due to the species presenting different charges with pH variation. For arsenic species determination, hydride generation atomic absorption spectrometry (HG–AAS) was employed. Copyright © 1999 John Wiley & Sons, Ltd.