Large-Scale Active-Set Box-Constrained Optimization Method with Spectral Projected Gradients

A new active-set method for smooth box-constrained minimization is introduced. The algorithm combines an unconstrained method, including a new line-search which aims to add many constraints to the working set at a single iteration, with a recently introduced technique (spectral projected gradient) for dropping constraints from the working set. Global convergence is proved. A computer implementation is fully described and a numerical comparison assesses the reliability of the new algorithm.     

Rate constants for the gas-phase reactions of Cl atoms with a series of hydrofluorocarbons and hydrochlorofluorocarbons at 298 ± 2 K

A relative rate method has been used to determine rate constants for the gas-phase reactions of a series of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) at 298 ± 2 K and atmospheric pressure of air. Based on a rate constant for the reaction of the Cl atom with CH₄ of (1.0 ± 0.2) ? 10^?13 cm³ molecule^?1 s^?1 at 298 K, the following Cl atom reaction rate constants (in units of 10^?15 cm³ molecule^?1 s^?1) were obtained: CH₃F, 340 ± 70; CH₃CHF₂, 240 ± 50; CH₂FCl, 110 ± 25; CHFCl₂, 21 ± 4; CHCl₂CF₃, 14 ± 3; CHFClCF₃, 2.7 ± 0.6; CH₃CFCl₂, 2.4 ± 0.5; CHF₂Cl, 2.0 ± 0.4; CH₂FCF₃, 1.6 ± 0.3; CH₃CF₂Cl, 0.37 ± 0.08; and CHF₂CF₃, 0.24 ± 0.05. These Cl atom reaction rate constants are compared with literature data and with the corresponding OH radical reaction rate constants. © John Wiley & Sons, Inc.     

Genus two extremal surfaces: Extremal discs, isometries and Weierstrass points

It is known that the largest disc that a compact hyperbolic surface of genusg may contain has radiusR=cosh⁻¹(1/2sin(π/(12g−6))). It is also known that the number of such (extremal) surfaces, although finite, grows exponentially withg. Elsewhere the authors have shown that for genusg>3 extremal surfaces contain only one extremal disc. Here we describe in full detail the situation in genus 2. Following results that go back to Fricke and Klein we first show that there are exactly nine different extremal surfaces. Then we proceed to locate the various extremal discs that each of these surfaces possesses as well as their set of Weierstrass points and group of isometries. Both authors partially supported by Grant BFM2000-0031 of the SGPI.MCYT.     

Efficient alkene synthesis on solid support using the Julia–Kocienski coupling

An efficient application of the Julia–Kocienski coupling for the olefination of aldehydes with resin-bound benzothiazol-2-yl and 1-phenyl-1H-tetrazol-5-yl sulfones is described. Olefins is generally obtained in high overall yield for the six-reaction steps.     

Low‐Level Laser Therapy and Sodium Diclofenac in Acute Inflammatory Response Induced by Skeletal Muscle Trauma: Effects in Muscle Morphology and mRNA Gene Expression of Inflammatory Markers

Pharmacological therapy is widely used in the treatment of muscle injuries. On the other hand, low‐level laser therapy (LLLT) arises as a promising nonpharmacological treatment. The aim of this study was to analyze the effects of sodium diclofenac (topical application) and LLLT on morphological aspects and gene expression of biochemical inflammatory markers. We performed a single trauma in tibialis anterior muscle of rats. After 1 h, animals were treated with sodium diclofenac (11.6 mg g^‐1 of solution) or LLLT (810 nm; continuous mode; 100 mW; 3.57 W cm^?2; 1, 3 or 9 J; 10, 30 or 90 s). Histological analysis and quantification of gene expression (real‐time polymerase chain reaction—RT‐PCR) of cyclooxygenase 1 and 2 (COX‐1 and COX‐2) and tumor necrosis factor‐alpha (TNF‐α) were performed at 6, 12 and 24 h after trauma. LLLT with all doses improved morphological aspects of muscle tissue, showing better results than injury and diclofenac groups. All LLLT doses also decreased (P < 0.05) COX‐2 compared to injury group at all time points, and to diclofenac group at 24 h after trauma. In addition, LLLT decreased (P < 0.05) TNF‐α compared both to injury and diclofenac groups at all time points. LLLT mainly with dose of 9 J is better than topical application of diclofenac in acute inflammation after muscle trauma.     

(E)‐Ethyl 3‐(3,4‐dihydroxyphenyl)prop‐2‐enoate: a natural polymorph extracted from Aristotelia chilensis (Maqui)

The natural title compound, C₁₁H₁₂O₄, extracted from the Chilean native tree Aristotelia chilensis (Maqui), is a polymorph of the synthetic E form reported by Xia, Hu & Rao [Acta Cryst. (2004), E 60 , o913–o914]. Both rotational conformers are identical from a metrical point of view, and only differ in the orientation of the 3,4‐dihydroxyphenyl ring with respect to the rest of the molecule, which leads to completely different crystal structure arrangements and packing efficiencies. The reasons behind both reside in the different hydrogen‐bonding interactions.     

Transient effects in electrolytic cells submitted to an external electric field

We analyse transient effects in an electrolytic cell submitted to an external voltage and determine the relaxation time of the redistribution of the ions and of the potential. We consider the case in which adsorption effects at the interface with the electrodes are present and show that the typical relaxation time, for applied voltage V ₀25 mV, is of the order of tens of seconds for commercial nematic liquid crystals. When V ₀>25 mV the linearized analysis is no longer valid. In this case, the relaxation time depends on the applied voltage. Increasing V ₀, but still remaining in the low amplitude limit, the relaxation time starts increasing. This indicates that the reduction of the actual field in the sample, for moderate values of V ₀, plays an important role. For large values of V ₀, the relaxation time is a decreasing function of V ₀. This result is interpreted in terms of a simple model, according to which the ionic charge is localized in a surface layer whose thickness depends on the amplitude of the applied voltage.     

Evaluating bound-constrained minimization software

Bound-constrained minimization is a subject of active research. To assess the performance of existent solvers, numerical evaluations and comparisons are carried on. Arbitrary decisions that may have a crucial effect on the conclusions of numerical experiments are highlighted in the present work. As a result, a?detailed evaluation based on performance profiles is applied to the comparison of bound-constrained minimization solvers. Extensive numerical results are presented and analyzed.