Fluid-fluid and fluid-solid transitions in the Kern-Frenkel model from Barker-Henderson thermodynamic perturbation theory

We study the Kern-Frenkel model for patchy colloids using Barker-Henderson second-order thermodynamic perturbation theory. The model describes a fluid where hard sphere particles are decorated with one patch, so that they interact via a square-well potential if they are sufficiently close one another, and if patches on each particle are properly aligned. Both the gas-liquid and fluid-solid phase coexistences are computed and contrasted against corresponding Monte Carlo simulations results. We find that the perturbation theory describes rather accurately numerical simulations all the way from a fully covered square-well potential down to the Janus limit (half coverage). In the region where numerical data are not available (from Janus to hard-spheres), the method provides estimates of the location of the critical lines that could serve as a guideline for further efficient numerical work at these low coverages. A comparison with other techniques, such as integral equation theory, highlights the important aspect of this methodology in the present context.     

The low level laser therapy effect on the remodeling of bone extracellular matrix

The low level laser therapy (LLLT) has been used as an option to accelerate the regeneration of bone tissue. In this study, both femurs of male Wistar rats (30 animals) were injured with a drill and the effect of LLLT using a laser diode (100 mW at 660 nm) in the bone matrix on the left paw measured. LLLT effect on the healing bone tissue matrix was evaluated by a combination of immunohistochemical histomorphometry, confocal immunofluorescence microscopy and isolation and characterization of glycosaminoglycans. Histomorphometric analysis showed that LLLT increased bone matrix and showing more organized. Alcian Blue and PAS staining seems to suggest differential glycosaminoglycans and glycoproteins. The data showed increased expression of chondroitin sulfate and hyaluronic acid, after reduction as the LLLT and mature bone, resembling the expression of osteonectin and biglycan. The difference in expression of siblings (DMP‐1, OPN and BSP) is in accordance with the repair accelerated bone formation after the application of LLLT as compared with control. The expression of osteonectin and osteocalcin supports their role in bone mineralization protein, indicating that LLLT accelerates this process. The overall data show that LLLT bone changes dynamic array, shortening the time period involved in the bone repair.     

The electrocatalytic activity of a supramolecular assembly of CoTsPc/FeT4MPyP on multi-walled carbon nanotubes towards L-glutathione, and its determination in human erythrocytes

The electrocatalytic activity of a supramolecular complex based on cobalt(II) phthalocyanine tetrasulfonate and iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin adsorbed on multi-walled carbon nanotubes for the oxidation of L-glutathione (GSH) was investigated at pH 7.4. Scanning electron microscopy and energy dispersive X-ray spectrometry were used to characterize the morphologies and composition of the materials. The modified electrode displayed efficient electrocatalytic activity in terms of oxidation of GSH at an oxidation potential of 0 V (versus Ag/AgCl). Cyclic voltammetry and amperometry indicated that the oxidation involves 2-electrons, with a heterogeneous rate constant of 4.9?×?10⁵ mol^?1 L s^?1. The response is linear from 2 to 210 μmol ?L^-1, the sensitivity is 1570 μA L mmol^?1, the detection limit is 0.03 μmol L^?1, and the relative standard deviation of 110 μmol L^?1 GSH was 2.6% (n?=?10). The modified electrode was applied to the determination of GSH in erythrocytes and the results were in agreement with those obtained by a method reported in the literature.     

Pneumatically assisted desorption/ionization: 1. Some thoughts on the possible ionization mechanism(s)

We have observed that spraying solvent droplets on a zopiclone tablet produced MH⁺ ions also in the absence of any electrical field and without the addition of organic acids to the sprayed solvent. The choice of a drug tablet as test bench has been done for the signal stability, higher than that observed when the drug is directly placed on a stainless steel surface. This behavior indicates that the formation of MH⁺ ions is mainly due to pneumatical effects and the results are discussed with respect to those obtained by other research groups. Different mechanisms contributing to MH⁺ production under these conditions are proposed and discussed. The local heating of the solvent thin layer present on the surface has been calculated and the small temperature increase (and the consequent small decrease of pK_a value) suggests that this effect can play only a minor role. However, different solvents have been employed for studying this aspect and, quite surprisingly, the best results have been obtained with acetonitrile (ACN). Experiments performed by spraying CD₃CN showed again the formation of MH⁺ and not MD⁺, and this excludes the role of ACN as protonating medium. A further thought was stimulated by the behavior observed by varying the sheath gas (N₂) flow, showing that the MH⁺ ion intensity increases by increasing the flow. Side effects related to the highest kinetic energy of the spraying droplets can be considered, but an active role of N₂ in the MH⁺ formation could be taken into account, by considering the possible ionization of N₂ by collisional phenomena. The N₂^+? ions could undergo a charge–exchange reaction with analyte molecules leading to a short‐lived odd electron ion which behaves as protonating media for neutral molecules. The above‐described mechanism does not require either the presence of electrical fields nor the addition of organic acid to the sprayer solvent and can give a rationale for what was observed when only pneumatical conditions are employed. Copyright © 2010 John Wiley & Sons, Ltd.     

Multi-scale structured, superhydrophobic and wide-angle, antireflective coating in the near-infrared region

Superhydrophobic self-cleaning surfaces were produced with simultaneous wide-angle optical transmittance in the near-infrared region and antireflection properties from combination of multi-scale surface topology based on silica nanoparticles, index grading and interference.     

Chiral flavanones from Amygdalus lycioides Spach: structural elucidation and identification of TNFalpha inhibitors by bioactivity-guided fractionation

Phytochemical investigation on the Amygdalus lycioides Spach branchelets resulted in the isolation of four chiral flavanones: (2R,3R)-Taxifolin, (2R,3R)-aromadendrin, (S)-5,7,3',5'-tetrahydroxyflavanone and (S)-naringenin. The flavanones were isolated by semi-preparative HPLC, their structures elucidated based on spectroscopic data and their absolute configuration assigned. As a part of our ethnobotanical-directed search for novel TNFα inhibitors, the bioassay-guided fractionation of the n-hexane-acetone (n-Hex-Ac, 1:1 v/v) Amygdalus lycioides Spach branchelets extract was performed. In this way, (S)-naringenin was identified as the constituent responsible for the TNFα blocking effect, being effective in vitro and in vivo after oral administration. This is the first investigation on bioactive secondary metabolites of Amygdalus lycioides Spach branchelets.     

Scenario optimization asset and liability modelling for individual investors

We develop a scenario optimization model for asset and liability management of individual investors. The individual has a given level of initial wealth and a target goal to be reached within some time horizon. The individual must determine an asset allocation strategy so that the portfolio growth rate will be sufficient to reach the target. A scenario optimization model is formulated which maximizes the upside potential of the portfolio, with limits on the downside risk. Both upside and downside are measured vis-à-vis the goal. The stochastic behavior of asset returns is captured through bootstrap simulation, and the simulation is embedded in the model to determine the optimal portfolio. Post-optimality analysis using out-of-sample scenarios measures the probability of success of a given portfolio. It also allows us to estimate the required increase in the initial endowment so that the probability of success is improved.     

Electronic spectra and intersystem spin‐orbit coupling in 1,2‐ and 1,3‐squaraines

The main photophysical properties of a series of recently synthetized 1,2‐ and 1,3‐squaraines, including absorption electronic spectra, singlet‐triplet energy gaps, and spin‐orbit matrix elements, have been investigated by means of density functional theory (DFT) and time‐dependent DFT approaches. A benchmark of three exchange‐correlation functionals has been performed in six different solvent environments. The investigated 1,2 squaraines have been found to possess two excited triplet states (T₁ and T₂) that lie below the energy of the excited singlet one (S₁). The radiationless intersystem spin crossing efficiency is thus enhanced in both the studied systems and both the transitions could contribute to the excited singlet oxygen production. Moreover, they have a singlet‐triplet energy gap higher than that required to generate the cytotoxic singlet oxygen species. According to our data, these compounds could be used in photodynamic therapy applications that do not require high tissue penetration. © 2014 Wiley Periodicals, Inc.     

Calculation of the effective speed of sound in corrugated pipes by multiple scales

The flow through corrugated pipes is known to lead to strong whistling tones which may be harmful in many industrial appliances. The mechanism is known to originate from a coupling between vortex shedding at the edges of the cavities forming the wall of the tube and the acoustical modes of the pipe. The latter depend upon the effective velocity of sound c_eff within the corrugated pipe. The purpose of this paper is to compute accurately this effective velocity of sound through an asymptotic calculation valid in the long-wave limit. Results are given for a number of geometries used in previous works, and compared with a simple model in which the effective speed of sound is function of the geometry of the pipe. The latter is found to work best for short cavities but significant disagreement is found for longer cavities. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A Practical and Efficient Synthesis of 2,5-Disubstituted-3,5-dihydro-imidazol-4-ones from Oxazolones

An alternative procedure for the synthesis of 2,5-disubstituted-3,5-dihydro-imidazol-4-ones from substituted oxazolones was evaluated. The initial oxazolone ring-opening reaction was examined with a variety of ammonia source compounds followed by the subsequent 3,5-dihydro-imidazol-4-one cyclization reaction, which was carried out with either an organic or inorganic base in aprotic solvents. In this article, we report the results of an efficient and straightforward procedure for the synthesis of 2,5-disubstituted-3,5-dihydro-imidazol-4-ones that gives satisfactory yield and quality.