Review on the application of nanobiosensors in food analysis

Nano-biosensors could be defined as biosensors, which are combined with nanotechnology by using several techniques. This strategy could be seen as a key to yielding device which exhibits rapid responses combined with very high sensitivities. In recent years as consumer demand traceability and legislators and account- ability in the food chain distribution has increased, the need for rapid and verifiable methods of food quality assurance has grown rapidly. Sensing technologies for food analysis including optical, chromatographic, colorimetric, etc. are employed. Biosensors allow the detection of analyte's wide spectrum in complex sample matrices, and have shown great promise in areas such as food analysis, environmental monitoring and bioprocess. Biosensors can be divided into six groups which depend on the method of signal transduction: magnetic, optical, electrochemical, mass, thermal and micromechanical sensors. The aim of this paper is to present the directions of the development of nano-biosensors and their useability to detect a range of biological and chemical compounds in the food industry market.     

The effect of reactor temperature gradient on microstructures of sodium borosilicate glass powders produced by ultrasonic spray pyrolysis technique

Sodium borosilicate glass powders were produced by ultrasonic spray pyrolysis technique for three different reactor temperature gradients and the effect of the reactor temperature gradient on the microstructures of the powders produced was investigated. A three-zone ultrasonic spray pyrolysis system reactor in which the temperatures of each zone could be controlled separately was designed for this purpose. When the drying speed is high, early shell formation was observed in the aerosol droplets due to the difference of the drying speed between inner and outer parts and hollow powders were produced. In order to produce dense powder particles, shell formation on the aerosol droplet should be prevented, therefore drying speed should be decreased. The powders produced were glass-structured, spherical shaped and with smooth surfaces. The density of the hollow powder particle was 1.9 g/cm³ while the density of the dense particle was 2.5 g/cm³.     

Polymerization of epoxidized soybean oil with maleinized polybutadiene

Epoxidized soybean oil (ESO) triglycerides were reacted with maleinized polybutadiene (MMPBD) to give plant‐oil‐based thermoset polymers. MMPBD samples were of two different molecular weights [high‐molecular‐weight maleinized polybutadiene (MMPBD‐H), maleate content = 10%, number‐average molecular weight (M_n) = 9000, and low‐molecular‐weight maleinized polybutadiene (MMPBD‐L), maleate content = 15%, M_n = 5000]. To increase the crosslink density of the product, a free‐radical initiator, benzoyl peroxide, was added to this mixture to further crosslink MMPBD through its double bonds. The characterizations of the products were done by dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, and IR spectroscopy. The ESO–MMPBD polymers were crosslinked rigid infusible polymers. ESO–MMPBD‐H–1 : 1 and ESO–MMPBD‐L–1 : 1 showed glass‐transition temperature values at −23, 78 and −17, 64°C, respectively, whereas the storage moduli of the two polymers at 25°C were 13 and 16 MPa, respectively. The storage moduli of the polymers remained the same or decreased with the addition of a free‐radical initiator. The storage moduli also decreased with increasing ESO concentration above a 1 : 1 epoxy‐to‐anhydride molar ratio. The surface hardness increased dramatically, and the equilibrium swelling ratio decreased with the addition of free‐radical initiator. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Photovoltaic textile structure using polyaniline/carbon nanotube composite materials

In this paper, an investigation of flexible electrodes for photovoltaic textile structures utilizing polymer‐based organic materials is presented. The composite structure consisting of a blend of water dispersible carbon nanotube:polyaniline (CNT:PANI) components with poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was applied to be used as the hole collecting electrode in photovoltaic textile applications. Both photovoltaic textiles and conventional solar cells were fabricated by using a blend of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT):(6,6)‐phenyl C61‐butyric acid methyl ester (PCBM). All devices were characterized by measuring current versus voltage characteristics under AM 1.5 conditions. The nanoscale morphology of the photovoltaic structures was investigated using scanning electron microscopy and atomic force microscopy.     

DEVELOPMENT OF SYNERGISTIC HEAT STABILIZERS FOR PVC FROM ZINC BORATE-ZINC PHOSPHATE

The importance of flame-retardant and smoke-suppressed poly(vinyl chloride) (PVC) compositions is increasing gradually in the polymer industry since PVC releases smoke and toxic gases (hydrogen chloride, HCl) during heating at temperatures above 140°C with the result of dehydrochlorination reaction. In this study, the synergistic effects of zinc borate (ZB)-zinc phosphate (ZP) on the thermal stability of PVC were investigated using thermal techniques. The induction and stability time values of PVC plastigels were obtained at 140° and 160°C. The results revealed that PVC plastigels having only ZP and ZB retarded dehydrochlorination of PVC compared with the unstabilized sample. However, the plastigels with both ZB and ZP had a superior synergistic effect on char formation of PVC. Since the induction periods of the samples having both ZB and ZP were higher than those of the unstabilized samples having only ZB or only ZP, the synergistic effect was observed.     

Highly selective ion-imprinted particles for solid-phase extraction of Pb ions

The Pb²⁺-imprinted (PHEMAC-Pb²⁺) particles were prepared by bulk polymerization as a solid-phase extraction (SPE) adsorbent. N-methacryloyl-(l)-cysteine (MAC) was used as functional monomer to have a well-shaped molecular geometry between MAC monomer and Pb²⁺ ions that provide molecular recognition based on well fitted cavities for Pb²⁺ ions after removal of template ions. The PHEMAC-Pb²⁺ particles were characterized and the applicability of these particles was investigated for the solid-phase extraction of Pb²⁺ ions from aqueous solutions and environmental samples. The PHEMAC-Pb²⁺ particles with a size range of 50–200 µm have a rough surface and macropores in bulk structure. The adsorption capacity of the PHEMAC-Pb²⁺ particles is relatively low (2.01 mg/g). However, the high selectivity towards competitive ions (Cd²⁺, Ni²⁺ and Cu²⁺) promises the PHEMAC-Pb²⁺ particles an alternative SPE adsorbent in literature. The relative selectivity coefficients of PHEMAC-Pb²⁺ particles for Pb²⁺/Ni²⁺, Pb²⁺/Cd²⁺ and Pb²⁺/Cu²⁺ were almost 71, 117 and 192 times greater than that of non-imprinted (PHEMAC) particles, respectively. Moreover, the reusability of the PHEMAC-Pb²⁺ particles was tested for several times and no significant loss in adsorption capacity was observed. The accuracy of the proposed procedure was also verified by the determination of Pb²⁺ ions in the certified reference material, LGC 6137 Estuarine sediment.     

Nitric Oxide Signalling in Descending Vasa Recta after Hypoxia/Re-Oxygenation

Reduced renal medullary oxygen supply is a key factor in the pathogenesis of acute kidney injury (AKI). As the medulla exclusively receives blood through descending vasa recta (DVR), dilating these microvessels after AKI may help in renoprotection by restoring renal medullary blood flow. We stimulated the NO-sGC-cGMP signalling pathway in DVR at three different levels before and after hypoxia/re-oxygenation (H/R). Rat DVR were isolated and perfused under isobaric conditions. The phosphodiesterase 5 (PDE5) inhibitor sildenafil (10⁻⁶ mol/L) impaired cGMP degradation and dilated DVR pre-constricted with angiotensin II (Ang II, 10⁻⁶ mol/L). Dilations by the soluble guanylyl cyclase (sGC) activator BAY 60-2770 as well as the nitric oxide donor sodium nitroprusside (SNP, 10⁻³ mol/L) were equally effective. Hypoxia (0.1% O₂) augmented DVR constriction by Ang II, thus potentially aggravating tissue hypoxia. H/R left DVR unresponsive to sildenafil, yet sGC activation by BAY 60-2770 effectively dilated DVR. Dilation to SNP under H/R is delayed. In conclusion, H/R renders PDE5 inhibition ineffective in dilating the crucial vessels supplying the area at risk for hypoxic damage. Stimulating sGC appears to be the most effective in restoring renal medullary blood flow after H/R and may prove to be the best target for maintaining oxygenation to this vulnerable area of the kidney.     

Diagnosis,Classification and Management of Mast Cell Activation Syndromes (MCAS) in the Era of Personalized Medicine

Mast cell activation (MCA) is seen in a variety of clinical contexts and pathologies, including IgE-dependent allergic inflammation, other immunologic and inflammatory reactions, primary mast cell (MC) disorders, and hereditary alpha tryptasemia (HAT). MCA-related symptoms range from mild to severe to life-threatening. The severity of MCA-related symptoms depends on a number of factors, including genetic predisposition, the number and releasability of MCs, organs affected, and the type and consequences of comorbid conditions. In severe systemic reactions, MCA is demonstrable by a substantial increase of basal serum tryptase levels above the individual’s baseline. When, in addition, the symptoms are recurrent, involve more than one organ system, and are responsive to therapy with MC-stabilizing or mediator-targeting drugs, the consensus criteria for the diagnosis of MCA syndrome (MCAS) are met. Based on the etiology of MCA, patients can further be classified as having i) primary MCAS where KIT-mutated, clonal, MCs are detected; ii) secondary MCAS where an underlying IgE-dependent allergy or other reactive MCA-triggering pathology is found; or iii) idiopathic MCAS, where neither a triggering reactive state nor KIT-mutated MCs are identified. Most severe MCA events occur in combined forms of MCAS, where KIT-mutated MCs, IgE-dependent allergies and sometimes HAT are detected. These patients may suffer from life-threatening anaphylaxis and are candidates for combined treatment with various types of drugs, including IgE-blocking antibodies, anti-mediator-type drugs and MC-targeting therapy. In conclusion, detailed knowledge about the etiology, underlying pathologies and co-morbidities is important to establish the diagnosis and develop an optimal management plan for MCAS, following the principles of personalized medicine.     

Multi-objective multi-armed bandit with lexicographically ordered and satisficing objectives

Machine Learning - We consider multi-objective multi-armed bandit with (i) lexicographically ordered and (ii) satisficing objectives. In the first problem, the goal is to select arms that are...