Effects of polymer molecular weight,concentration, and role of polyethylene glycol as additive on polyacrylonitrile homopolymer membranes

Polyacrylonitrile (PAN), is an important base polymer to cast porous membranes. In this work, a detailed study of the effects of molecular weight of PAN homopolymer and its concentration on the cast membrane has been undertaken. The effects of molecular weight of additive polyethylene glycol (PEG) and its concentration have also been investigated. The membranes are cast using dimethyl formamide as solvent using phase inversion technique. They are characterized in terms of porosity, water permeability, molecular weight cut off, average pore diameter, contact angle, and tensile strength at breaking point. Fourier transform infrared spectroscopy and scanning electron microscopy are used to characterize the chemical and morphological changes of the membrane surface. Further studies have been considered to evaluate the antifouling property of various membranes using filtration of bovine serum albumin solution. Membrane modified by PEG 400 membrane shows an improved separation performance and antifouling characteristics. POLYM. ENG. SCI., 54:2375–2391, 2014. © 2013 Society of Plastics Engineers     

Angiotensin-I converting enzyme inhibitory and antioxidant activity of bioactive peptides produced by enzymatic hydrolysis of skin from grass carp (Ctenopharyngodon idella)

Grass carp skin pieces were homogenized in water and hydrolyzed by Alcalase®, collagenase, proteinase K, and/or trypsin at their optimum conditions. Samples were taken at various degrees of hydrolysis and were evaluated for antioxidant, antimicrobial, and angiotensin-converting enzyme inhibitory activities. Alcalase and collagenase completely hydrolyzed the skin with different rates, and released peptides with antioxidant and angiotensin-converting enzyme-inhibitory activity. These activities increased linearly with increasing degrees of hydrolysis. Subsequent incubation of the collagenase hydrolysates with trypsin slightly increased the antioxidant activity. Proteinase K, although only partially hydrolyzing the skin, also catalyzed the release of peptides with antioxidant and angiotensin-converting enzyme-inhibitory activities. These results show that skin by-products from grass carp can be a source of bioactive peptides produced by a one-step reaction. Such hydrolysates may be applied in food products to prolong shelf life and provide beneficial effects on blood pressure.     

Energy Drinks: An Assessment of Their Market Size,Consumer Demographics,Ingredient Profile,Functionality, and Regulations in the United States

ABSTRACT: The consumption of energy drinks is rapidly increasing, as demonstrated by their large market growth. The targeted demographic group is teenagers, young adults, 18 to 34 y old; although expansion into nontraditional markets is also occurring. It is claimed that energy drinks can offer an increased energy boost related to their ingredient profile of caffeine, taurine, herbal extracts, and vitamins. Research suggests that energy drink formulations, in addition to increasing energy utilization, may also improve mood, enhance physical endurance, reduce mental fatigue, and increase reaction time. However, in most cases, the corresponding mechanisms of action are not clear. In addition, concerns have been raised over their safety and with a currently weak regulatory environment, efforts need to be made to ensure consumer safety. The objective of this article is to review the current U.S. energy drink market with emphasis on its market size, target demographic, active ingredients, potential benefits, safety, and regulations.     

Spice use in food: Properties and benefits

Spices are parts of plants that due to their properties are used as colorants, preservatives, or medicine. The uses of spices have been known since long time, and the interest in the potential of spices is remarkable due to the chemical compounds contained in spices, such as phenylpropanoids, terpenes, flavonoids, and anthocyanins. Spices, such as cumin (cuminaldehyde), clove (eugenol), and cinnamon (cinnamaldehyde) among others, are known and studied for their antimicrobial and antioxidant properties due to their main chemical compounds. These spices have the potential to be used as preservatives in many foods namely in processed meat to replace chemical preservatives. Main chemical compounds in spices also confer other properties providing a variety of applications to spices, such as insecticidal, medicines, colorants, and natural flavoring. Spices provide beneficial effects, such as antioxidant activity levels that are comparable to regular chemical antioxidants used so they can be used as a natural alternative to synthetic preservatives. In this review, the main characteristics of spices will be described as well as their chemical properties, different applications of these spices, and the advantages and disadvantages of their use.     

The effects of a moisture-wicking fabric shirt on the physiological and perceptual responses during acute exercise in the heat

This study investigated the effects that a form fitted, moisture-wicking fabric shirt, promoted to have improved evaporative and ventilation properties, has on the physiological and perceptual responses during exercise in the heat. Ten healthy male participants completed two heat stress tests consisting of 45 min of exercise (50% VO_2peak) in a hot environment (33 °C, 60% RH). One heat stress test was conducted with the participant wearing a 100% cotton short sleeved t-shirt and the other heat stress test was conducted with the participant wearing a short sleeved synthetic shirt (81% polyester and 19% elastane). Rectal temperature was significantly lower (P < 0.05) in the synthetic condition during the last 15 min of exercise. Furthermore, the synthetic polyester shirt retained less sweat (P < 0.05). As exercise duration increases, the ventilation and evaporation properties of the synthetic garment may prove beneficial in the preservation of body temperature during exercise in the heat.     

Oxidative post-treatments for enhanced corrosion resistance of aluminium electrodeposited from ionic liquids

In this paper we report the results of a study on the corrosion properties of carbon steel (UNI Fe360B) coated with a thin aluminium layer electrodeposited from ionic liquids and subsequently post-treated in an oxidizing environment. Two different types of treatments were investigated: thermal oxidation in air and electrochemical anodization. We found that heat treatments provided only a modest improvement of the anticorrosion properties while the electrochemical treatment produced a significant improvement.     

Optical and electrical characterization of a gold nanoparticle dispersion in a chiral liquid crystal matrix

We report on the effect of gold nanoparticle (Au NP) dispersion in a chiral nematic liquid crystal (LC). Polarized optical microscopy and X-ray diffraction measurements evidence the insurgence of an order change in the LC host. Moreover, a comparative analysis based on dielectric and voltammetric spectroscopies performed on pure LC and on Au NP-doped LC shows that Au NP’s presence besides affecting LC order influences its electric properties: ion conductivity results importantly reduced, and beyond a threshold value of the applied field electrophoresis phenomena are induced.