Dextran/poly(acrylic acid) mixtures as miscible blends

Bioartificial polymeric materials based on blends of dextran and poly(acrylic acid) were prepared in form of films and characterized in order to evaluate the miscibility of the natural component with the synthetic one. Films with different composition ratios were prepared by solution casting and analyzed by dynamic mechanical-thermal analysis, differential scanning calorimetry, and scanning electron microscopy. The obtained results indicate that dextran is miscible with poly(acrylic acid). The miscibility was mainly ascertained on the bases of the occurrence of a single composition-dependent glass transition temperature in each blend and also on the bases of the transparency and homogeneity of the films. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2089–2094, 1997     

Enzyme-based bioartificial polymeric materials: the α-amylase–poly(vinyl alcohol) system

The possibility of realizing bioartificial polymeric materials from blends of the enzyme α-amylase (EC 3.2.1.1) and poly(vinyl alcohol), in the form of film and hydrogel, was investigated. The interactions at molecular level between the enzyme and the synthetic polymer have been studied by calorimetry, X-ray diffractometry and morphological analysis. A certain degree of interaction through which the α-amylase molecules influence the crystallinity of the poly(vinyl alcohol) was observed. The thermal stability of the enzyme in the blends was enhanced, while its biological activity did not vary significantly. In addition, hydrogels prepared by a freeze–thawing method can be considered suitable for manufacturing delivery systems capable of releasing enzymes which maintain their full biological activity. ©1997 SCI     

Obesity and Bone: A Complex Relationship

There is a large literature on the relationship between obesity and bone. What we can conclude from this review is that the increase in body weight causes an increase in BMD, both for a mechanical effect and for the greater amount of estrogens present in the adipose tissue. Nevertheless, despite an apparent strengthening of the bone witnessed by the increased BMD, the risk of fracture is higher. The greater risk of fracture in the obese subject is due to various factors, which are carefully analyzed by the Authors. These factors can be divided into metabolic factors and increased risk of falls. Fractures have an atypical distribution in the obese, with a lower incidence of typical osteoporotic fractures, such as those of hip, spine and wrist, and an increase in fractures of the ankle, upper leg, and humerus. In children, the distribution is different, but it is not the same in obese and normal-weight children. Specifically, the fractures of the lower limb are much more frequent in obese children. Sarcopenic obesity plays an important role. The authors also review the available literature regarding the effects of high-fat diet, weight loss and bariatric surgery.     

用VIC密炼机混炼轮胎白炭黑胶料

近年来 ,由于白炭黑这种矿物填充剂可使轮胎的机械性能得到改善 ,因而被越来越多地应用于轮胎工业中。但是 ,采用大灵活性较大的密炼机混炼白炭黑胶料会遇到很多问题和困难。白炭黑为具有高表面能的极性分子 ,自身之间易于产生强烈的相互作用 ,形成稳定的团粒状的网络 ,难以将其打碎并分散在橡胶相中。采用偶联剂对白炭黑表面进行硅烷化处理后 ,可得到部分改善。但硅烷化过程要求温度在130～ 160℃之间 ,在这个温度范围内 ,白炭黑的水分减少 ,粒子之间的作用力减弱 ,易于打碎和分散 ,且更有利于与橡胶相反应。基于上述原因 ,对于生产轮胎用…     

Effect of chemical composition on gas transport properties of ethylene-based ionomers

Transport properties of oxygen and carbon dioxide in three ethylene–acrylic acid ionomers, characterized by different amounts of acrylic acid groups, percentage of neutralization and counterion type, have been investigated. Gas permeation experiments have been performed in the 25–65°C range. Gas permeabilities, diffusivities and solubilities were evaluated along with activation energies and heats of solution. The transport properties have been analysed in order to correlate the effect of counterion type and its concentration on macromolecular mobility and on polymer–gas interaction, which in turn are the factors determining permeation rate.     

Template polymerization of sodium methacrylate onto poly(allylamine) hydrochloride

The radical polymerization in aqueous solution of sodium methacrylate in the presence of poly(allylamine) hydrochloride as a template was studied using dilatometry. The properties of the polyelectrolyte complexes resulting from these template polymerizations were investigated and compared with those of the poly(sodium methacrylate)/poly(allylamine) hydrochloride complexes obtained by simple mixing of the preformed polymers. The kinetic study provides evidence for the presence of a strong template effect and indicates that the polymerization occurs by a zip mechanism. The results of the different characterization analyses have shown that the complexes obtained by template polymerization have a more ordered structure than the complexes prepared by mixing the two polymers.     

Homocysteine Solution-Induced Response in Aerosol Jet Printed OECTs by Means of Gold and Platinum Gate Electrodes

Homocysteine (Hcy) is a non-protein, sulfur-containing amino acid, which is recognized as a possible risk factor for coronary artery and other pathologies when its levels in the blood exceed the normal range of between 5 and 12 μmol/L (hyperhomocysteinemia). At present, standard procedures in laboratory medicine, such as high-performance liquid chromatography (HPLC), are commonly employed for the quantitation of total Hcy (tHcy), i.e., the sum of the protein-bound (oxidized) and free (homocystine plus reduced Hcy) forms, in biological fluids (particularly, serum or plasma). Here, the response of Aerosol Jet-printed organic electrochemical transistors (OECTs), in the presence of either reduced (free) and oxidized Hcy-based solutions, was analyzed. Two different experimental protocols were followed to this end: the former consisting of gold (Au) electrodes’ biothiol-induced thiolation, while the latter simply used bare platinum (Pt) electrodes. Electrochemical impedance spectroscopy (EIS) analysis was performed both to validate the gold thiolation protocol and to gain insights into the reduced Hcy sensing mechanism by the Au-gated OECTs, which provided a final limit of detection (LoD) of 80 nM. For the OECT response based on Platinum gate electrodes, on the other hand, a LoD of 180 nM was found in the presence of albumin-bound Hcy, with this being the most abundant oxidized Hcy-form (i.e., the protein-bound form) in physiological fluids. Despite the lack of any biochemical functionalization supporting the response selectivity, the findings discussed in this work highlight the potential role of OECT in the development of low-cost point-of-care (POC) electronic platforms that are suitable for the evaluation, in humans, of Hcy levels within the physiological range and in cases of hyperhomocysteinemia.     

Inactivation and injury of total coliform bacteria after primary disinfection of drinking water by TiO2 photocatalysis

In this study the potential application of TiO(2) photocatalysis as primary disinfection system of drinking water was investigated in terms of coliform bacteria inactivation and injury. As model water the effluent of biological denitrification unit for nitrate removal from groundwater, which is characterized by high organic matter and bacteria release, was used. The injury of photocatalysis on coliform bacteria was characterized by means of selective (mEndo) and less selective (mT7) culture media. Different catalyst loadings as well as photolysis and adsorption effects were investigated. Photocatalysis was effective in coliform bacteria inactivation (91-99% after 60 min irradiation time, depending on both catalyst loading and initial density of coliform bacteria detected by mEndo), although no total removal was observed after 60 min irradiation time. The contribution of adsorption mechanism was significant (60-98% after 60 min, depending on catalyst loading) compared to previous investigations probably due to the nature of source water rich in particulate organic matter and biofilm. Photocatalysis process did not result in any irreversible injury (98.8% being the higher injury) under investigated conditions, thus a bacteria regrowth may take place under optimum environment conditions if any final disinfection process (e.g., chlorine or chlorine dioxide) is not used.     

Simulation and wake analysis of a single vertical axis wind turbine

Because of several design advantages and operational characteristics, particularly in offshore farms, vertical axis wind turbines (VAWTs) are being reconsidered as a complementary technology to horizontal axial turbines. However, considerable gaps remain in our understanding of VAWT performance since cross‐flow rotor configurations have been significantly less studied than axial turbines. This study examines the wakes of VAWTs and how their evolution is influenced by turbine design parameters. An actuator line model is implemented in an atmospheric boundary layer large eddy simulation code, with offline coupling to a high‐resolution blade‐scale unsteady Reynolds‐averaged Navier–Stokes model. The large eddy simulation captures the turbine‐to‐farm scale dynamics, while the unsteady Reynolds‐averaged Navier–Stokes captures the blade‐to‐turbine scale flow. The simulation results are found to be in good agreement with three existing experimental datasets. Subsequently, a parametric study of the flow over an isolated VAWT, carried out by varying solidities, height‐to‐diameter aspect ratios and tip speed ratios, is conducted. The analyses of the wake area and velocity and power deficits yield an improved understanding of the downstream evolution of VAWT wakes, which in turn enables a more informed selection of turbine designs for wind farms. Copyright © 2016 John Wiley & Sons, Ltd.