Fracture detection by grating moiré and in-plane ESPI techniques

Optical interferometry techniques have been used for high-precision displacement measuring. Commonly, in-plane sensitive arrangements use two symmetrical collimated wavefronts for object surface illumination. However, this is a limitation when large object surface, has to be analyzed. In this case spherical illumination is needed. As a consequence of using non-collimated symmetrical dual-beams the sensitivity vector varies with the local position on the surface target. Then, this kind of illumination is also capable of detecting a lightly and systematic out-of-plane component of deformation. In this paper a theoretical analysis of the sensitivity vector components behavior is made. Each component of the sensitivity vector to minimize the required displacement component uncertainty is calculated. This study is important in the stage of planning any interferometric measurement experiment, particularly, for moiré grating interferometric technique, which has been used only in collimated illumination. By using a spherical dual-beam optical setup, the present work shows results of fracture measuring by using moiré and speckle interferometric methods. As a result, advantages and disadvantages of both techniques are discussed and an accuracy study is reported.     

6‐Deoxyhexoses from l‐Rhamnose in the Search for Inducers of the Rhamnose Operon: Synergy of Chemistry and Biotechnology

In the search for alternative non‐metabolizable inducers in the l ‐rhamnose promoter system, the synthesis of fifteen 6‐deoxyhexoses from l ‐rhamnose demonstrates the value of synergy between biotechnology and chemistry. The readily available 2,3‐acetonide of rhamnonolactone allows inversion of configuration at C4 and/or C5 of rhamnose to give 6‐deoxy‐d ‐allose, 6‐deoxy‐d ‐gulose and 6‐deoxy‐l ‐talose. Highly crystalline 3,5‐benzylidene rhamnonolactone gives easy access to l ‐quinovose (6‐deoxy‐l ‐glucose), l ‐olivose and rhamnose analogue with C2 azido, amino and acetamido substituents. Electrophilic fluorination of rhamnal gives a mixture of 2‐deoxy‐2‐fluoro‐l ‐rhamnose and 2‐deoxy‐2‐fluoro‐l ‐quinovose. Biotechnology provides access to 6‐deoxy‐l ‐altrose and 1‐deoxy‐l ‐fructose.     

Rubbery wound closure adhesives. II. initiators for and initiation of 2‐octyl cyanoacrylate polymerization

The polymerization of 2‐octyl cyanoacrylate (OctCA) initiated by five N‐bases [N,N‐dimethyl‐p‐toluidine (DMT), pyridine (Pyr), triethyl amine (Et₃N), azobicyclo[2.2.2]octane (ABCO), and diazobicylo[2.2.2]octane (DABCO)] was investigated. Our main objective was to assess the suitability and relative reactivity of these initiators for neat OctCA polymerization as wound closure adhesives. Methodologies were developed to determine stir‐stop and set times of OctCA polymerization and to use these quantities to assess initiation reactivity. According to these studies Et₃N, ABCO, DABCO, and Pyr are most reactive initiators, while DMT is much less reactive. Polymerizations were much faster in the presence of small amounts of tetrahydrofuran than toluene, indicating solvent polarity effects. Initiator reactivity is discussed in terms of structural parameters. NMR and MALDI‐TOF analyses of low molecular weight P(OctCA) prepared with DMT did not show evidence for the expected aromatic head group proposed by earlier investigators, which suggests complex initiation mechanism. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1652–1659     

Breathable rubbery skin protectors: Design,synthesis, characterization,and properties of cyanoacrylated silicone rubber networks

We extended our investigations of rubbery wound closure adhesives and created novel flexible networks by crosslinking cyanoacrylated silicone rubbers (i.e., commercial methylhydrosiloxane‐dimethylsiloxane copolymers, PMHS‐co‐PDMS) with N,N‐dimethyl‐p‐toluidine in tetrahydrofuran and hexamethyldisiloxane solvents at room temperature. Cyanoacrylation was achieved by hydrosilating (anthracene‐protected) allyl cyanoacrylate with PMHS‐co‐PDMS. Steric hindrance and the molecular weight of the copolymer strongly affect the extent of hydrosilation. The rate of crosslinking is proportional with the number of cyanoacrylate groups in the copolymer and networks form in seconds with appropriate amounts of initiator. Networks on porcine skin yield well‐adhering flexible optically‐transparent colorless conformal coatings of good “feel” appropriate for clinically useful non‐occlusive “breathable” skin or wound protectors. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1367‐1372     

Investigations of the Properties of l-Histidine in Aqueous NaCl Solutions at Different Temperatures

Density and viscosity experimental data for l-histidine in NaCl aqueous solutions were obtained at different salt and different amino acid concentrations in the range of temperatures between 293.15 and 323.15 K. The results have been correlated and analyzed in order to evaluate the influence of electrolyte concentration and temperature on the volumetric and viscometric properties of the solutions. The apparent molar volumes and the transfer volumes of l-histidine in aqueous NaCl solutions at different salt and amino acid molalities over entire temperature range were calculated from experimental density data. The viscosity experimental data have been analyzed with Jones–Dole equation and the Falkenhagen (A) and the Jones–Dole coefficient (B) have been calculated in order to evaluate the interactions occurring in the systems. The B viscosity coefficients were found to be positive for all conditions, showing a kosmotropic effect of solutes, indicating an alignment of zwitterions with ions/water dipoles. A comparison of standard partial molar volumes for some amino acids in water and NaCl aqueous solutions shows that they increase with molecular mass and complexity of the lateral side chain of the amino acid.     

Work Hardening Effects in Gellan Gum Gels1

Abstract

Gellan gum is a bacterial polysaccharide that is marketed as a broad spectrum gelling agent. The shear and Young's moduli, and the fracture strength of gellan gels increase with increasing ionic strength, pass through maxima and then decrease to zero at higher ionic strength. The position of the maxima depend on the valency of added counterions and are virtually independent of polymer concentration. At low ionic strength the measured rheological parameters show small variability but these values become increasingly variable with increasing ionic strength. Stress relaxation experiments were carried out in order to examine the mechanical behaviour of gellan gels and to explain these effects. At low ionic strength the gels approximate to elastic solids whereas at high ionic strength the increased stress relaxation is colloid-like in behaviour. However, unlike colloidal dispersions, the magnitude of the stress relaxation decreases on successive applications of stress and the relaxation modulus increases. The gels work harden. Such behaviour is attributed to a heterogeneous structure within the gel.     

General Health Benefits and Pharmacological Activities of Triticum aestivum L.

Common wheat (Triticum aestivum), one of the world’s most consumed cereal grains, is known for its uses in baking and cooking in addition to its medicinal uses. As this plant’s medical benefits are enormous and scattered, this narrative review was aimed at describing the pharmacological activities, phytochemistry, and the nutritional values of Triticum aestivum. It is a good source of dietary fiber, resistant starch, phenolic acids, alkylresorcinols, lignans, and diverse antioxidant compounds such as carotenoids, tocopherols and tocotrienols. These constituents provide Triticum aestivum with a wide range of pharmacological properties, including anticancer, antimicrobial, antidiabetic, hypolipemic, antioxidant, laxative, and moisturizing effects. This review summarized the established benefits of wheat in human health, the mode of action, and different clinical, in vitro and in vivo studies for different varieties and cultivars. This review also gives an insight for future research into the better use of this plant as a functional food. More clinical trials, in vivo and in vitro studies are warranted to broaden the knowledge about the effect of Triticum aestivum on nutrition-related diseases prevention, and physical and mental well-being sustenance.     

Pharmacological Activities of Soursop (Annona muricata Lin.)

Soursop (Annona muricata Lin.) is a plant belonging to the Annonaceae family that has been widely used globally as a traditional medicine for many diseases. In this review, we discuss the traditional use, chemical content, and pharmacological activities of A.muricata. From 49 research articles that were obtained from 1981 to 2021, A.muricata’s activities were shown to include anticancer (25%), antiulcer (17%), antidiabetic (14%), antiprotozoal (10%), antidiarrhea (8%), antibacterial (8%), antiviral (8%), antihypertensive (6%), and wound healing (4%). Several biological activities and the general mechanisms underlying the effects of A.muricata have been tested both in vitro and in vivo. A.muricata contains chemicals such as acetogenins (annomuricins and annonacin), alkaloids (coreximine and reticuline), flavonoids (quercetin), and vitamins, which are predicted to be responsible for the biological activity of A. muricata.     

Study of the influence of water matrix components on admicellar sorbents

Hemimicelle-based and/or admicelle-based solid-phase extraction (SPE) has recently been proved to be a fruitful strategy for the extraction and concentration of a wide variety of organic pollutants. This research focus on the effect of river and wastewater matrix components on the adsorption of sodium dodecyl sulfate (SDS) onto alumina, which is the most-used sorbent in hemimicelle-based and/or admicelle-based SPE, and we discuss the analytical consequences of the modifications observed. The effect of electrolytes (0.1 M NaCl), precipitating agents (127 and 333 mg L⁻¹ CaCl₂) and major organic components in wastewater (19.8 mg L⁻¹ carbohydrates, proteins and fats and 10 mg L⁻¹ linear alkylbenzene sulfonates (LAS) and rivers (8 mg L⁻¹ humic acid) on the SDS adsorption isotherm was investigated. Also, the global effect of matrix components was assessed using a river sample. Three types of sorbents were considered (hemimicelles, mixed hemimicelles/admicelles and admicelles). Electrolytes were found to compete with surfactant molecules for charge surface sites in the early part of the hemimicellar region; precipitating agents yield insoluble salts with the aqueous surfactant in equilibrium with admicelle-based sorbents; and organic matter did not have any influence at all. The matrix component concentrations investigated were above the usual range present in rivers and wastewater, which makes this study applicable to a wide number of environmental water samples. From the results obtained, simple rules were established to prevent and detect matrix-induced surfactant adsorption modifications, which permits us to know, a priori, the suitability of these sorbents for a specific application and allows the development of more straightforward and robust methods.