Structural,spectroscopic and computational study of 5‐(substituted phenylazo)‐3‐cyano‐1‐ethyl‐6‐hydroxy‐4‐methyl‐2‐pyridones

Ten 5‐(substituted phenylazo)‐3‐cyano‐1‐ethyl‐6‐hydroxy‐4‐methyl‐2‐pyridones were studied (five new compounds) to provide insight into the electronic effects of diverse substituents located at different positions in their phenyl moieties. The structural features of these dyes were examined by combining experimental and theoretical approaches. The crystal structures of two derivatives were revealed by X‐ray crystallography and diverse packing modes owing to different intermolecular interactions (π–π stacking and lone pair–π interactions, as well as hydrogen bonds) were found. A study on lattice energy and energy related to the molecular pairs obtained from their crystal packing was performed. The tautomerism and ionisation of the dyes in ethanol or N,N ‐dimethylformamide solution were rationalised in terms of diazo component substitution pattern.     

Application of the monoliths in DeNOx catalysis

Air pollution abatement catalysis refers to catalytic technologies and processes for reducing emissions of environmentally unacceptable compounds. Major problems related to these catalytic clean-up technologies are mobile emission control, removal of nitrogen oxides (NO_x), sulphur compounds, volatile organic compounds (VOCs) and other pollutants generated by industry or by other stationary sources. Application of the monolith catalysts and/or reactors is a key solution to these problems. This overview describes basic features of the monolithic structures and discusses their development and application prospects focusing on DeNO_x catalysis. The status and ongoing modeling of the monolithic reactors are outlined. Particular emphasis is put on experimental validation and practical applications of the mathematical models of a monolithic reactor.     

Resveratrol Protects Cardiac Tissue in Experimental Malignant Hypertension Due to Antioxidant,Anti-Inflammatory,and Anti-Apoptotic Properties

Hypertension is one of the most prevalent and powerful contributors of cardiovascular diseases. Malignant hypertension is a relatively rare but extremely severe form of hypertension accompanied with heart, brain, and renal impairment. Resveratrol, a recently described grape-derived, polyphenolic antioxidant molecule, has been proposed as an effective agent in the prevention of cardiovascular diseases. This study was designed to examine chronic resveratrol administration on blood pressure, oxidative stress, and inflammation, with special emphasis on cardiac structure and function in two models of experimental hypertension. The experiments were performed in spontaneously (SHRs) and malignantly hypertensive rats (MHRs). The chronic administration of resveratrol significantly decreased blood pressure in both spontaneously and malignant hypertensive animals. The resveratrol treatment ameliorated morphological changes in the heart tissue. The immunohistochemistry of the heart tissue after resveratrol treatment showed that both TGF-β and Bax were not present in the myocytes of SHRs and were present mainly in the myocytes of MHRs. Resveratrol suppressed lipid peroxidation and significantly improved oxidative status and release of NO. These results suggest that resveratrol prevents hypertrophic and apoptotic consequences induced by high blood pressure with more pronounced effects in malignant hypertension.     

Experimental and theoretical insight into the electronic properties of 4-aryl-5-arylazo-3-cyano-6-hydroxy-2-pyridone dyes

In this paper, spectroscopic and quantum mechanical investigation of nine 4-aryl-5-arylazo-3-cyano-6-hydroxy-2-pyridone dyes was performed, and obtained density functional theory (DFT) results were compared with experimental data. The structural and spectroscopic properties of azo-2-pyridone dyes were studied by DFT using B3LYP, CAM-B3LYP, and M06-2X methods with a 6-311++G(d,p) basis set. Comparison of results reveals that the scaled theoretical vibrational frequencies of azo dyes are in good agreement with experimental data. The time-dependent DFT calculated and experimental ultraviolet-visible (UV-vis) absorption spectra are also in good agreement. The effect of electron-donating –OCH₃ and electron-withdrawing –NO₂ groups on the structural parameters, vibrational frequencies, UV-vis absorption, and natural bond orbital (NBO) atomic charges were thoroughly analysed. Vibrational, UV-vis, and NBO analyses confirm that investigated dyes exist in the hydrazo tautomeric form in the solid state and ethanol solution. These analyses signify the occurrence of intramolecular charge transfer in these azo-pyridone dyes.     

Synthesis and characterization of thermoplastic poly(ester–siloxane)s

Two series of thermoplastic poly(ester–siloxane)s, based on poly(dimethylsiloxane) (PDMS) as the soft segment and poly(butylene terephthalate) as the hard segment, were synthesized by two‐step catalyzed transesterification reactions in the melt. Incorporation of soft poly(dimethylsiloxane) segments into the copolyester backbone was accomplished in two different ways. The first series was prepared based on dimethyl terephthalate, 1,4‐butanediol and silanol‐terminated poly(dimethylsiloxane) (PDMS‐OH). For the second series, the PDMS‐OH was replaced by methyl diesters of carboxypropyl‐terminated poly(dimethylsiloxane)s. The syntheses were optimized in terms of both the concentration of catalyst, tetra‐n‐butyl‐titanate (Ti(OBu)₄), and stabilizer, N,N′‐diphenyl‐p‐phenylene‐diamine, as well as the reaction time. The reactions were followed by measuring the inherent viscosities of the reaction mixture. The molecular structures of the synthesized poly(ester–siloxane)s were verified by ¹H NMR spectroscopy, while their thermal properties were investigated using differential scanning calorimetry. © 2001 Society of Chemical Industry     

Development of the timber-glass upgrade module for the purpose of its installation on energy-inefficient buildings in the refurbishment process

The current research study presents the development of the upgrade module consisting of a timber frame structure with the optimal glazing size in the east-, south- and west-oriented façades for the purpose of energy-efficient refurbishment of the existing energy-inefficient buildings. Such construction module could open the way to simple installation onto the existing residential, public or office buildings of various shapes and ensure better energy performance of the refurbished buildings. The optimal glazing size of the east-, south- and west-oriented façades of the module with the optimal shape is determined by the glazing-to-wall area ratio where the sum total of the annual energy need for heating and cooling of the module is minimal. The sum of the annual energy is defined through an extensive parametric numerical analysis including variations regarding the module’s aspect ratio, the thermal transmittance of its envelope and the glazing size in its east-, south- and west-oriented façades. A parametric analysis carried out in the previously described manner leads to analytic functional dependence between the energy consumption and the module’s design parameters. It is therefore possible to make a fairly simple preliminary estimate of the annual energy need, in addition to defining the optimal floor plan shape of the module along with the optimal proportion of glazing in its east-, south- and west-oriented façades. The optimal proportion of glazing varies from 24 to 91% in the south-oriented façade, from 7 to 43% in the east and from 9 to 55% in the west façade, at the thermal transmittance of the thermal envelope 0.100 W/(m² K). The variation in the optimal glazing proportion of the module with the thermal transmittance of the thermal envelope 0.165 W/(m² K) ranges from 14 to 85% in the east, from 28 to 97% in the south and from 16 to 68% in the west-oriented façade. The presented research study permits a choice of the optimal module design with respect to baseline characteristics of the existing building and allows for a more systematic as well as energy-efficient refurbishment process.     

General Anesthesia and the Young Brain: The Importance of Novel Strategies with Alternate Mechanisms of Action

Over the past three decades, we have been grappling with rapidly accumulating evidence that general anesthetics (GAs) may not be as innocuous for the young brain as we previously believed. The growing realization comes from hundreds of animal studies in numerous species, from nematodes to higher mammals. These studies argue that early exposure to commonly used GAs causes widespread apoptotic neurodegeneration in brain regions critical to cognition and socio-emotional development, kills a substantial number of neurons in the young brain, and, importantly, results in lasting disturbances in neuronal synaptic communication within the remaining neuronal networks. Notably, these outcomes are often associated with long-term impairments in multiple cognitive-affective domains. Not only do preclinical studies clearly demonstrate GA-induced neurotoxicity when the exposures occur in early life, but there is a growing body of clinical literature reporting similar cognitive-affective abnormalities in young children who require GAs. The need to consider alternative GAs led us to focus on synthetic neuroactive steroid analogues that have emerged as effective hypnotics, and analgesics that are apparently devoid of neurotoxic effects and long-term cognitive impairments. This would suggest that certain steroid analogues with different cellular targets and mechanisms of action may be safe alternatives to currently used GAs. Herein we summarize our current knowledge of neuroactive steroids as promising novel GAs.     

Copolymers based on poly(butylene terephthalate) and polycaprolactone‐block‐polydimethylsiloxane‐block‐polycaprolactone

A series of novel thermoplastic elastomers, based on poly(butylene terephthalate) (PBT) and polycaprolactone‐block‐polydimethylsiloxane‐block‐polycaprolactone (PCL‐PDMS‐PCL), with various mass fractions, were synthesized through melt polycondensation. In the synthesis of the poly(ester‐siloxane)s, the PCL blocks served as a compatibilizer for the non‐polar PDMS blocks and the polar comonomers dimethyl terephthalate and 1,4‐butanediol. The introduction of PCL‐PDMS‐PCL soft segments resulted in an improvement of the miscibility of the reaction mixture and therefore in higher molecular weight polymers. The content of hard PBT segments in the polymer chains was varied from 10 to 80 mass%. The degree of crystallinity of the poly(ester‐siloxane)s was determined using differential scanning calorimetry and wide‐angle X‐ray scattering. The introduction of PCL‐PDMS‐PCL soft segments into the polymer main chains reduced the crystallinity of the hard segments and altered related properties such as melting temperature and storage modulus, and also modified the surface properties. The thermal stability of the poly(ester‐siloxane)s was higher than that of the PBT homopolymer. The inclusion of the siloxane prepolymer with terminal PCL into the macromolecular chains increased the molecular weight of the copolymers, the homogeneity of the samples in terms of composition and structure and the thermal stability. It also resulted in mechanical properties which could be tailored. Copyright © 2010 Society of Chemical Industry     

Rheological properties of bitumen modified with ethylene butylacrylate glycidylmethacrylate

This article presents experimental results related to rheological viscoelastic properties of polymer modified bitumens, PmBs. Experiments were performed by a dynamical shear rheometer before and after thermo‐oxidative aging. Two types of bitumens with different asphaltene contents were modified by the addition of two types of reactive ethylene terpolymers, Elvaloy AM, and Elvaloy 4170, with a different percentage of reactive functional group, glycidylmethacrylate, GMA. Results of the investigation indicate that the degree of reactive polymer modification is a function of bitumen type, bitumen‐polymer compatibility, and polymer concentration. Polymer modification improves the following physical properties of the base bitumen: penetration, softening point, temperature susceptibility, and elastic recovery. Reactive polymers are effective binder modifiers that improve the susceptibility to high temperature of asphalt mixes, and also their rutting resistance, contribute to their good storage stability and make them less sensitive to aging. This is a result of the formation of a chemical bond between the polymer and molecules of asphaltenes. POLYM. ENG. SCI., 54:1056–1065, 2014. © 2013 Society of Plastics Engineers