Development and validation of a sandwich ELISA for the determination of potentially allergenic sesame (Sesamum indicum) in food

This paper presents a sandwich enzyme-linked immunosorbent assay (ELISA) that allows the determination of traces of sesame in food. Chicken anti-sesame antibodies, used as coating antibodies, and rabbit anti-sesame antibodies, used as secondary antibodies, were prepared by immunization with a protein extract of white, peeled sesame. The ELISA did not show any cross-reactivity with 19 food ingredients commonly found in sesame-containing foodstuffs such as seeds, nuts, and cereals. In whole grain bread, crisp toast, and snacks, the limit of detection (S/N = 3) was 0.5, 0.5, and 0.3 μg sesame protein/g, and the limit of quantification (S/N = 10) was 0.6, 0.8, and 1.4 μg sesame protein/g, respectively. The analysis of blank food matrices (whole grain bread, white bread, crisp toast, and snacks) spiked with sesame protein at four spike levels generally resulted in mean recoveries from 72% to 145%. In the case of spiking blank food matrices with sesame seeds, the ELISA proved to be more accurate for whole wheat cookies than for whole wheat bread.     

ABS blends with phenoxy: morphology,thermal, mechanical and rheological properties

Blends of ABS (acrylonitrile–butadiene–styrene) with phenoxy(poly(hydroxyether bisphenol A)) were prepared using a Branender single screw extruder. Scanning and transmission electron micrographs (SEM, TEM) showed a typical two-phase morphology; particle-in-matrix (90/10) (ABS/phenoxy by weight), 70/30, 10/90), island/sea (30/70) and co-continuous (50/50) morphologies. The glass transition temperature (T_g) of SAN was almost unchanged in the blends, while the T_g of phenoxy increased by about 5 °C in the blends. The synergistic effect of tensile modulus and strength was noted in ABS-rich blends, where a drastic drop of ductility was seen, and the results were interpreted in terms of rubber particle migration form SAN to phenoxy phase, which was visualized by TEM. Melt viscosity showed yield in ABS-rich blends, and generally followed the log additivity.     

Effect of addition sesame seeds powder with different ratio on microstructural and some properties of low fat Labneh

Sesame seeds (Sesamum indicum L.) are probably the most ancient oil seed crops used in functional Labneh preperation. The goal of the present study was to explore the quality of Labneh made from skim milk fortified with 0%, 2%, 4%, and 6% sesame seeds powder (SSP) as alternative to fat. Control Labneh made from whole milk and their treatments with SSP were stored for 21 days at 5 ± 1 °C. The physiochemical, microbiological, and organoleptic properties were determined in fresh and stored Labneh (for 7, 14, and 21 days) as well as amino acids and microstructures were measured in fresh Labneh. The results showed that sesame seed contains up to 58.9% oil, 15.81% protein, 6.83% fiber, 11.03% carbohydrates, 14.84% antioxidant activity and 32.71 mg/100 g sesamol. The data presented that total solid, fat and acidity were increased while protein and ash contents were decreased in control Labneh compared with Labneh treatments. These all values increased with increasing the amount of SSP, except the acidity value decreased with increasing the amount of SSP. In various fresh Labneh samples, the major essential amino acid was Leucine and non-essential amino acid was Glutamic than the other amino acids. Microbiological examination of Labneh revealed that the total bacterial counts increased throughout the storage period. However moulds and yeasts were not detected at the first week then slightly detected and increased at the end of storage period. Coliform bacteria and spore-forming bacteria didn't observe in all Labneh treatments as storage progressed. Scanning electron microscopy showed that the control Labneh samples had more compact structure and fusion into big aggregates without voids. Labneh made from skim milk had numerous open, loose and less dense protein networks with spaces. No major differences were observed in the Labneh made from skim milk using 2% and 4% sesame seeds . Labneh made from skim milk using 6% sesame seeds was more intensive and thicker casein matrix than the other Labneh treatments. Organoleptic scores revealed that Labneh fortified with 4% sesame seeds powder have the highest acceptability properties.     

Effect of nano‐polystyrene (nPS) on thermal,rheological, and mechanical properties of polypropylene (PP)

Polystyrene nanoparticles (nPS) in the range of 10–100 nm with spherical shape were synthesized by oil/water (o/w) microemulsion process. In this process ammonium persulfate (APS) as an initiator, sodium dodecyl sulphate as a surfactant and n‐pentanol as cosurfactant were used. Isolated nPS was characterized by FTIR and ¹H NMR spectroscopy. DSC studies of nPS showed higher T_g as compared to bulk PS. The effect of lower weight percentage (wt%) of nPS on the mechanical, rheological, and thermal properties of PP was investigated. The blends were prepared individually on brabender plastograph by incorporating nPS of ～60 nm with different wt% of loading (i.e., 0.10–0.5%). It was shown from the experimental results that thermal, rheological, and mechanical properties were increased as the polymer particles blended with PP. Blends with 0.25 wt% loading of nPS exhibit better properties compared with that of other wt% loadings. The improvements in properties were due to the close packing of PP chains as recorded by improvement in crystallinity of PP with the addition of nPS as shown by SEM. Copyright © 2010 John Wiley & Sons, Ltd.     

Transient rheological behavior of lyotropic (acetyl)(ethyl)cellulose/m-cresol solutions

The chiroptical properties and transient rheological behavior of (acetyl)(ethyl)cellulose (AEC) m-cresol liquid crystalline solutions have been investigated. Chiroptical properties were manipulated through (i) increasing degree of acetylation of ethyl cellulose (EC), and (ii) blending AEC with EC. At the same average degree of acetylation (DA), the chiroptical properties of pure AEC were different from those of the EC/AEC mixtures. However, at the same DA, the AEC and mixed AEC/EC solutions showed similar steady state flow and oscillatory behaviors, but the transient behaviors were different. At high flow rates the mixed AEC/EC solutions exhibited double recoil after cessation of steady-state flow, whereas the AEC solutions showed double recoil only in the high DA AEC solutions. All solutions, pure and mixed, had the same stress relaxation behavior. Both pitch and handedness affected the transient behavior. After cessation of high shear rate flow, the rate of modulus evolution decreased with increasing pitch, and was faster in right-handed mesophases than in left-handed ones at a similar pitch.     

Influence of poly(ethylene oxide) brushes on the rheological properties of MgO colloidal suspensions in water

A combined experimental and multiscale simulation study of the influence of polymer brush modification on interactions of colloidal particles and rheological properties of dense colloidal suspensions has been conducted. Our colloidal suspension is comprised of polydisperse MgO colloidal particles modified with poly(ethylene oxide) (PEO) brushes in water. The shear stress as a function of shear rate was determined experimentally and from multiscale simulations for a suspension of 0.48 volume fraction colloids at room temperature for both bare and PEO-modified MgO colloids. Bare MgO particles exhibited strong shear thinning behavior and a yield stress on the order of several Pascals in both experiments and simulations. In contrast, simulations of PEO-modified colloids revealed no significant yielding or shear thinning and viscosity only a few times larger than solvent viscosity. This behavior is inconsistent with results obtained from experiments where modification of colloids with PEO brushes formed by adsorption of PEO-based comb-branched chains resulted in relatively little change in suspension rheology compared to bare colloids over the range of concentration of comb-branch additives investigated. We attribute this discrepancy in rheological properties between simulation and experiment for PEO-modified colloidal suspensions to heterogeneous adsorption of the comb-branch polymers.     

Thermal behavior,dynamic mechanical properties and rheological properties of poly(butylene succinate) composites filled with nanometer calcium carbonate

PBS/nano-CaCO₃ composites with various nano-CaCO₃ weight fractions were prepared by melt blending. The thermal behavior, dynamic mechanical properties and rheological properties of the composites were investigated. DSC measurements revealed that the nano-CaCO₃ particles had little influence on the crystallization and melting behavior of PBS. Thermogravimetric analysis showed that the introduction of nano-CaCO₃ tended to improve the thermal stability of PBS. Dynamic mechanical analysis showed that the G′ and G″ of the PBS/nano-CaCO₃ composites were improved significantly when the nano-CaCO₃ content was not more than 3wt%, while the G′ and G″ were mainly decided by the PBS matrix when the nano-CaCO₃ content exceeded 3wt%. Rheological results showed that G′ < G″ over the frequency range, illustrating the viscous behavior of the samples. The η* of all the samples remained almost constant when the frequency was not more than 0.25 rad/s, which showed the characteristic of a Newtonian fluid. A strong shear thinning effect was observed for all the samples when the frequency exceeded 0.25 rad/s. Furthermore, the microstructure and the relaxation mechanism of the PBS/nano-CaCO₃ composites mainly depended on the PBS matrix.     

聚丙撑碳酸酯的流动性能表征

本文研究了聚丙撑碳酸酯的流动性能及其影响因素，实验表明聚丙撑碳酸酯为假塑性流体，它的表观粘度随着温度升高而降低，流动活化能随着剪切速率增加而变小，并得到了表观粘度与粘均分子量之间的定量关系．     

Effect of ethylene-co-vinyl acetate-glycidylmethacrylate and cellulose microfibers on the thermal,rheological and biodegradation properties of poly(lactic acid) based systems

The properties and biodegradation behavior of blends of poly(lactic acid) (PLA) and ethylene-vinyl acetate-glycidylmethacrylate copolymer (EVA-GMA), and their composites with cellulose microfibers (CF) were investigated. The blends and composites were obtained by melt mixing and the morphology, phase behavior, thermal and rheological properties of PLA/EVA-GMA blends and PLA/EVA-GMA/CF composite films were investigated as a function of the composition. The disintegrability in composting conditions was examined by means of morphological, thermal and chemical analyses to gain insights into the post-use degradation processes. The results indicated a good compatibility of the two polymers in the blends with copolymer content up to 30 wt.%, while at higher EVA-GMA content a phase separation was observed. In the composites, the presence of EVA-GMA contributes to improve the interfacial adhesion between cellulose fibers and PLA, due to interactions of the epoxy groups of GMA with hydroxyls of CF. The addition of cellulose microfibers in PLA/EVA-GMA system modifies the rheological behavior, since complex viscosity increased in presence of fibers and decreased with an increase in frequency. Disintegration tests showed that the addition of EVA-GMA influence the PLA disintegration process, and after 21 days in composting conditions, blends and composites showed faster degradation rate in comparison with neat PLA due to the different morphologies induced by the presence of EVA-GMA and CF phases able to allow a faster water diffusion and an efficient PLA degradation process.     

Polymer nanoparticles: their effect on rheological,thermal, and mechanical properties of linear low‐density polyethylene (LLDPE)

Rheological, thermal, and mechanical properties of polymer particle/LLDPE blends were studied in this paper. The blends were prepared individually by incorporating nanoparticles of polystyrene (nPS) of ～60 nm and polymethyl methacrylate (nPMMA) of ～50 nm with different wt% loading (i.e., 0.10–0.5%). It was shown from the experimental results that rheological, thermal and mechanical properties were increased as polymer particles blended with LLDPE. Blends with 0.25 wt% loading of nPS and 0.5 wt% loading of nPMMA exhibited better rheological, thermal, and mechanical properties compared with that of other wt% loadings. The improvements in properties were due to the close packing of LLDPE chains as recorded by improvement in crystallinity of LLDPE with addition of nPS and nPMMA as shown by SEM. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of thermal degradation on rheological properties for poly(3-hydroxybutyrate)

Thermal degradation at processing temperature and the effect on the rheological properties for poly(3-hydroxybutyrate) have been studied by means of oscillatory shear modulus and capillary extrusion properties, with the aid of molecular weight measurements. Thermal history at processing temperature depresses the viscosity because of random chain scission. As a result, gross melt fracture hardly takes place with increasing the residence time in a capillary rheometer. Moreover, it was also found that the molecular weight distribution is independent of the residence time, whereas the inverse of the average molecular weight is proportional to the residence time. Prediction of average molecular weight with a constant molecular weight distribution makes it possible to calculate the flow curve following generalized Newtonian fluid equation proposed by Carreau as a function of temperature as well as the residence time.     

Characterization and electrochemical applications of a carbon with high density of surface functional groups produced from beer yeast

Carbon materials enriched with nitrogen and oxygen surface functional groups were obtained by pyrolyzing strained beer yeast at 750 °C under an inert atmosphere. Physical and surface properties of the carbon obtained were characterized by X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Raman spectrometry, and X-ray photoelectron spectroscopy. Results show that the carbon possesses an amorphous structure, a spherical morphology, and a high density of surface functional groups. Electrochemical properties were evaluated by cyclic voltammetry, a galvanostatic charge–discharge technique, and electrochemical impedance spectroscopy. The carbon has 989.65 mAh·g⁻¹ of initial discharge capacity and a stable cycle performance for a Li–C cell. A specific capacitance of 120 F·g⁻¹ was obtained for a single carbon electrode and good cycle performance was achieved for a symmetrical supercapacitor fabricated using this carbon. These carbons derived from strained beer yeast have promising applications in energy storage and conversion systems.     

Multiwalled carbon nanotubes reinforced poly (ether‐ketone) nanocomposites: Assessment of rheological,mechanical, and electromagnetic shielding properties

This study investigates the effect of multiwalled carbon nanotubes (MWCNTs) content on rheological, mechanical, and EMI shielding properties in Ka band (26.5‐40 GHz) of poly (ether‐ketone) [PEK] prepared by melt compounding using twin screw extruder. Transmission electron microscopy (TEM) and field emission gun scanning electron microscopy (FEG‐SEM) studies were adopted to identify dispersion of nanotubes in PEK matrix. TEM and SEM images showed uniform dispersion of MWCNTs in PEK/MWCNT composites even at loading of 5 wt%. The rheological studies showed that the material experiences viscous (fluid) to elastic (solid) transition at 1 wt% loading beyond which nanotubes form continuous network throughout the matrix which in turn promotes reinforcement. Additionally, Van‐Gurp Palmen plot (phase angle vs complex modulus) and values of damping factor further confirm that the material undergoes viscous to elastic transition at 1 wt% loading. This reinforcement effect of nanotubes is reflected in enhanced mechanical properties (flexural strength and flexural modulus). Flexural strength and flexural modulus of PEK showed an increment of 17% upon incorporation of 5 wt% of MWCNTs. Total shielding effectiveness (SE_T) of −38 dB with very high shielding effectiveness due to absorption (SE_A ~ −34 dB) was observed at 5 wt% loading of MWCNTs in PEK matrix in the frequency range of 26.5‐40 GHz (Ka band).     

Poly(lactic acid)/organoclay nanocomposites: Thermal,rheological properties and foam processing

In this study, polymer nanocomposites based on poly(lactic acid) (PLA) and organically modified layered silicates (organoclay) were prepared by melt mixing in an internal mixer. The exfoliation of organoclay could be attributed to the interaction between the organoclay and PLA molecules and shearing force during mixing. The exfoliated organoclay layers acted as nucleating agents at low content and as the organoclay content increased they became physical hindrance to the chain mobility of PLA. The thermal dynamic mechanical moduli of nanocomposites were also improved by the exfoliation of organoclay; however, the improvement was reduced at high organoclay content. The dynamic rheological studies show that the nanocomposites have higher viscosity and more pronounced elastic properties than pure PLA. Both storage and loss moduli increased with silicate loading at all frequencies and showed nonterminal behavior at low frequencies. The nanocomposites and PLA were then foamed by using the mixture of CO₂ and N₂ as blowing agent in a batch foaming process. Compared with PLA foam, the nanocomposite foams exhibited reduced cell size and increased cell density at very low organoclay content. With the increase of organoclay content, the cell size was decreased and both cell density and foam density were increased. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 689–698, 2005     

Crystallization,mechanical, thermal and rheological properties of polypropylene composites reinforced by magnesium oxysulfate whisker

Polypropylene(PP) composites containing magnesium oxysulfate whisker(MOSw) or lauric acid(LA) modified MOSw(LAMOSw) were prepared via melt mixing in a torque rheometer. The heterogeneous nucleating effect of LAMOSw was clearly observed in polarized light microscopy(PLM) pictures with the presence of an abundance of small spherulites. MOSw exhibited no nucleation effect and formed a few spherulites with large size. Compared with PP/MOSw composites, PP/LAMOSw exhibited better impact strength, tensile strength and nominal strain at break, ascribing to three possible reasons:(i) more β-crystal PP formed,(ii) better dispersity of LAMOSw in PP matrix and(iii) the plasticizing effect of LA. The results of dynamic mechanical thermal analysis(DMTA) indicated that brittleness of the PP matrix at low temperature was improved by the addition of LAMOSw, while the interfacial interactions between MOSw and PP matrix were actually weakened by LA, as evidenced by the higher tanδ values over the entire range of test temperatures. In terms of the rheological properties of the composites, both the η* and G′ at low frequencies increase with the addition of MOSw or LAMOSw, indicating that the PP matrix was transformed from liquid-like to solid-like. However, a network of whiskers did not form because no plateau was found in the G′ at low frequencies. With low filler content, LAMOSw produced a stronger solid-like behavior than MOSw mainly due to the better dispersion of the LAMOSw in PP matrix. However, for highly-filled composites, the η* of PP/LAMOSw at low frequencies was smaller than that of PP/MOSw composite, since the particleparticle contact effect played a major role.     

Mechanical properties of polyamide-12 layered silicate nanocomposites and their relations with structure

The mechanical properties of polyamide-12/Cloisite 30B (PA12/C30B) nanocomposites prepared by melt compounding were studied as a function of clay volume fraction φ under various processing conditions. All measured mechanical characteristics, Young's modulus, yield stress, strain at break and stress at break, exhibit a transition at φ_p1%, identified with a percolation threshold. Also, the linear and non-linear mechanical properties appeared to depend on the degree of exfoliation of the structure, which can be tuned by the processing conditions. The three-phase Ji's theoretical model was used to predict Young's modulus as a function of clay concentration, focusing on the influence of the degree of exfoliation. Experimental yield stress data were fitted to Pukanszky's model and discussed in terms of PA12/C30B interfacial adhesion.     

Crystallization,rheological, and mechanical properties of PLLA/PEG blend with multiwalled carbon nanotubes

Functionalized multiwalled carbon nanotubes (FMWCNTs) were introduced into poly(L‐lactide)/polyethylene glycol (PLLA/PEG) blend and the effects of FMWCNTs on crystallization behaviors, rheological, and mechanical properties of PLLA/PEG/FMWCNTs were investigated. The results show that FMWCNTs exhibit good distribution in the nanocomposites and absorb some PEG to agglomerate around them. The crystallization behavior of PLLA in the nanocomposites is greatly dependent on the content of FMWCNTs. At low content of FMWCNTs, the addition of FMWCNTs improves the crystallization behavior of PLLA by enhancing the crystallization temperature and accelerating the crystallization rate, whereas at high content of FMWCNTs, the crystallization of PLLA is restricted to a certain degree. Rheological properties show the formation of the network structure of FMWCNTs at high content, which is the main reason for the retarded crystallization behavior of PLLA due to the network structure providing restriction to mobility and diffusion of PLLA chains to crystal growth fronts. The mechanical properties show that FMWCNTs exhibit reinforcement effect for plasticized PLLA. Copyright © 2010 John Wiley & Sons, Ltd.     

Recent progress in coordination chemistry,photo-physical properties,and applications of pyridine-based Cu(I) complexes

Abstract

Copper(I) [Cu(I)] complexes offer cheap and alternative materials for several real-life applications. Pyridine (Py), bipyridine (Bpy), and related analogues have strong donating ability with propensity to ease functionalization via modern synthetic protocols. A large number of Cu(I) complexes/clusters/polymers bearing functionalized Py-based ligands have emerged with rich coordination chemistry, fascinating structures, and intriguing photo-physical properties. This article sheds light on recent advances in the coordination chemistry and photophysical properties of Cu(I) complexes/clusters/polymers and their applications in the areas of optoelectronics (OE) (light emitting devices [LEDs] and dye-sensitized solar cells [DSSCs]) and sensing (aliphatic and aromatic gases).     

Superhard boron suboxide (B6O): Crystal structure,synthesis, properties,applications, and materials based thereon

A review of reported data on the crystal structure, synthesis, and properties of boron suboxide B₆O, which is a superhard material (hardness of up to 55 GPa, as measured in single crystals), and composites based on it is presented. Methods for the synthesis of B₆O with a icosahedral structure and for the growing of crystals at high temperature and high pressure are described. The mechanical and operational characteristics of composite materials based on B₆O are summarized; the resistance of B₆O to oxidation is analyzed, and the properties of B₆O–diamond and B₆O–B₄C composite materials are described.     

Mechanical and rheological properties of poly(ethylene-co-ethyl acrylate) as a function of carbon black content

Carbon black (CB) filled poly(ethylene-co-ethyl acrylate) (EEA-CB) is used as conductive phase in conductive polymer composites (CPC). Electrical conductivity of CPC obtained from blends of immiscible polymers results from CB particles localization within the material, which depends on composition and processing conditions. It is particularly important to control viscosity of such systems as this parameter determines both the phase morphology and conductive pathway structure. The small scale, at which CB particle aggregation/dispersion phenomena occur within CPC, makes direct observations difficult. But the effect of carbon black particles/polymers interactions is clearly visible by means of rheological measurements. A strong reinforcing effect of CB on CPC in both solid and liquid states has been noticed. This phenomenon has been analyzed using classical models as a function of temperature and CB content. The results confirm the necessity of CPC rheology control especially during the process to achieve good reproducibility of electrical properties.