In situ studies of bovine serum albumin adsorption onto functionalized polystyrene latices monitored with a quartz crystal microbalance technique

The adsorbability of bovine serum albumin (BSA) onto poly(styrene‐co‐itaconic acid) (PS–IA), poly(styrene‐co‐hydroxyethyl methacrylate) (PS–HEMA), poly(styrene‐co‐acrylic acid) (PS–AA), and poly(styrene‐co‐methacrylic acid) (PS–MAA) latices were investigated with a quartz crystal microbalance. The amount adsorbed onto the functionalized latices, except for PS–MAA, was greater than that adsorbed onto polystyrene (PS) latex. To explain this result, two kinds of interaction forces were considered, hydrogen bonding and hydrophobic interactions, whereas electrostatic interaction was assumed to be small. When comparing the two extremes of hydrophobic interaction and hydrogen bonding, the latter was stronger. The corrected adsorption mass suggested that the BSA molecules were adsorbed onto the PS–MAA latex in a side‐on mode. However, in the case of the PS, PS–IA, PS–HEMA, and PS–AA latices, the BSA molecules were probably adsorbed in multiple layers. The presence of the BSA in the latex particle surface was verified by attenuated total reflectance/Fourier transform infrared spectroscopy and atomic force microscopy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42055.     

Effects of plasma treatment on greenhouse polyethylene cover aged under sub‐Saharan conditions

The effects of natural ageing, in sub‐Saharan regions, on treated low density polyethylene by cold plasma are presented in this work. The data analysis is performed by comparing the changes of physical, mechanical and structural effects on the material surface induced by plasma treatment with regard to the natural abrasion effect due to sand wind. Plasma treatments for short durations are applied to neutral LDPE (low density polyethylene) films. Few seconds suffice to observe chemical changes on the samples. The treated samples are then subjected to natural ageing in the region of Ouargla (south of Algeria), characterized by very frequent sand wind. The characterization of the effects of plasma treatment and its combination with sand wind is performed using XPS (X‐ray Photoelectron Spectroscopy), FTIR (Fourier Transform Infrared spectrometry), and mechanical tensile testing. The results led to conclude a synthesis of new materials on the surface that significantly change the material surface properties and physico‐chemical properties of material, more particularly, optical, and mechanical properties are thus strongly affected. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Solvent optimization extraction of antioxidants from foxtail millet species’ insoluble fibers and their free radical scavenging properties

In this study, water and 80% of four organic solvents were employed to optimize the extraction of antioxidants from two species of foxtail millet’s insoluble fibers under the same temperature, time, and solid/solvent ratio. The results showed that the acetone was able to extract the maximum amount of antioxidants (2.32 mg/g fiber for white specie and 3.86 mg/g fiber for yellow specie) followed by methanol and propanol from both samples. The neutral and the ethanol on the other hand extracted small amount of the antioxidants from the two fiber materials. While considerable level of Total Polyphenols Content (TPC) was recorded in both the water and the organic solvents’ extracts, only traces of Total Flavonoid content (TFC) were observed in water, methanol and ethanol extracts. Propanol and acetone extracts was negative to the TFC test.     

Microwave drying kinetics of jack pine wood: determination of phytosanitary efficacy,energy consumption,and mechanical properties

The aims of this study were to determine (1) the effects of microwave irradiation on the drying kinetics of jack pine wood, (2) the phytosanitary efficacy, and (3) the processing energy consumption and mechanical strength of the dried product. Microwave drying experiments were performed at 2.45 GHz frequency and at microwave powers ranging from 300 to 1000 W. Results indicate that higher microwave power and initial wood temperature and lower sample thickness increases the internal sample temperature, improves the drying rate, and reduces both drying time and energy consumption. The microwave irradiation efficacy to sanitize jack pine wood boards was determined in terms of temperature/time combinations based on actual drying kinetics according to standards for phytosanitary measures. The energy required to dry 12 mm thick wood board samples at microwave power ranging from 300 to 1000 W was in the range of 36.4–12.3 MJ/kg of water, respectively, for up to 65% energy consumption savings. The impact of microwave power on the mechanical properties was not statistically significant, although mechanical properties tended to decrease with increasing power.     

Essential oils of Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart collected from three localities of north Tunisia—Krib, Bargou and Nefza—were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin–Ciocalteu method, and antioxidant effectiveness, using the 2,2‐diphenyl‐1‐picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p‐cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), γ‐terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC₅₀, ranged from 59 to 80 mg L^?1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg^?1 dry weight, varied from 9.37 to 17.70 g kg^?1 dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p‐cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated. Copyright © 2010 Society of Chemical Industry     

Design of cable-driven parallel manipulators for a specific workspace using interval analysis

In this paper, we present a method, based on interval analysis, to solve the problem of designing cable-driven parallel manipulators (CDPMs) for a desired workspace. The constraint of having positive cable tensions ensuring the equilibrium of the platform has to be satisfied within the given workspace. The proposed algorithm is based on interval analysis, which covers the entire workspace and hence guarantees a singularity-free workspace. Furthermore, the algorithm is capable of finding all possible solutions for this problem and an optimal one is selected according to the user-defined criterion. Two examples are selected to show the efficiency of the developed algorithm in solving this complex problem. The first one deals with the design of a planar CDPM and the second one considers a spatial CDPM. In both cases, the algorithm succeeded to find all possible designs from which the designer can select a solution that fits best his application.     

Potential hypoglycaemic effects of insoluble fibres isolated from foxtail millets [Setaria italica (L.) P. Beauvois]

Insoluble fibres were isolated from the two varieties of foxtail millet (white and yellow) grains and evaluated for their hypoglycaemic effects by in vitro studies. The hypoglycaemic effects of these fibres were compared with those of commercial soy insoluble fibre. The results revealed that minimum and maximum amounts of glucose were adsorbed on each sample at 10 and 200 μmol g^?1 glucose concentrations respectively, indicating that the glucose adsorption capacity (GAC) of the fibre materials was proportional to glucose concentration for all samples. There was significant (P < 0.05) difference among all the fibre materials in relation to their GAC values. In the case of the effects of the fibres on glucose diffusion, the millets' insoluble fibres performed better than that of the commercial soy insoluble fibres. The glucose dialysis retardation indexes at the end of the maximum dialysis time were 1.1%, 27.4% and 22.6% for soy bean insoluble fibre, white foxtail millet insoluble fibre and yellow foxtail millet insoluble fibre in that order. The study showed that hypoglycaemic effects of yellow and white foxtail millet fibres were comparable to the commercial soy insoluble fibre.     

Mathematical modeling in genetic networks: relationships between the genetic expression and both chromosomic breakage and positive circuits

The human genome with its 23 pairs of chromosomes, is the result of evolution. This evolution has been ruled by the mutation process and also by the physiological and pathological reorganization of the genomic material inside or between the chromosomes, which are conditioning the genomic variability. This reorganization is starting at singular points on the short or long chromosomic arms, called crossing-over, or translocations, insertions, break points. In this paper, we will show that these points, also called weak points or hot spots of the genome are correlated, independently of their origin. In addition, we will give some properties of the genetic interaction matrices in terms of attractors of the genetic expression dynamics.