Effect of solvents on the dynamic viscoelastic behavior of poly(methyl methacrylate) film prepared by solvent casting

Poly(methyl methacrylate) films were prepared by dissolving the polymer in chloroform, toluene and tetrahydrofuran, with identical concentrations of 200 mg/mL, and drop casting the solutions on Teflon surface at room temperature. The thermal, thermomechanical and structural properties have been investigated by differential scanning calorimetry, dynamic mechanical analyzer, and Fourier transform infrared spectroscopy, respectively. The dynamic mechanical behavior of the films has been measured over a temperature range of 30–150 °C, using sinusoidal stress with a frequency of 2 Hz. The samples prepared from tetrahydrofuran showed the highest storage modulus, indicating a higher polymer chain entanglement in that solvent, whereas the samples prepared from chloroform showed the lowest storage modulus. The samples prepared from chloroform, which showed the weakest mechanical properties, also showed the lowest glass transition temperature, which is evidence of the plasticization and solvent retention mechanism of chloroform. The spectroscopic analysis confirmed the solvent-polymer interactions giving rise to the above mentioned effects.     

Structural investigation and dielectric studies on Mn substituted Pb(Zr0.65Ti0.35)O3 perovskite ceramics

Polycrystalline samples of manganese substituted lead zirconium titanate (PZMT) with general formula Pb(Zr_0.65−xMn_xTi_0.35)O₃ ceramics have been synthesised by high temperature solid state reaction technique. X-ray diffraction (XRD) patterns were recorded at room temperature to study the crystal structure employing Rietveld technique. All the patterns could be refined to R3c space group with rhombohedral symmetry. Bond lengths and angles have been calculated from refined parameters. Microstructural properties of the materials were analysed by scanning electron microscope (SEM) and compositional analysis were carried out by energy dispersive spectrum (EDS) measurements. All the materials exhibit ferroelectric to paraelectric transition. The Curie temperature (T_c) increases with the Mn concentration. We have observed that dielectric constant decreases and AC conductivity increases with the frequency. The correlation between lattice parameters and T_c for the present samples has been observed.     

Selective growth of silica nanowires using an Au catalyst for optical recognition of interleukin-10

The vapor-liquid-solid (VLS) growth procedure has been extended for the selective growth of silica nanowires on SiO(2) layer by using Au as a catalyst. The nanowires were grown in an open tube furnace at 1100?°C for 60?min using Ar as a carrier gas. The average diameter of these bottom-up nucleated wires was found to be 200?nm. Transmission electron microscopy analysis indicates the amorphous nature of these nanoscale wires and suggests an Si-silica heterostructure. The localized silica nanowires have been used as an immunoassay template in the detection of interleukin-10 which is a lung cancer biomarker. Such a nanostructured platform offered a tenfold enhancement in the optical response, aiding the recognition of IL-10 in comparison to a bare silica substrate. The role of nanowires in the immunoassay was verified through the quenching behavior in the photoluminescence (PL) spectra. Two orders of reduction in PL intensity have been observed after completion of the immunoassay with significant quenching after executing every step of the protocol. The potential of this site-specific growth of silica nanowires on SiO(2) as a multi-modal biosensing platform has been discussed.     

Thermal and high hydrostatic pressure inactivation of myrosinase from green cabbage: A kinetic study

Myrosinase, a family of enzymes which coexist with glucosinolates in all Brassica vegetables, catalyses the hydrolysis of glucosinolates to yield compounds that can have beneficial effects on human health. In this study, the thermal and pressure inactivation of myrosinase from green cabbage was kinetically investigated. Thermal inactivation started at 35 °C and inactivation kinetics was studied in the temperature range 35-55 °C. Thermal inactivation of green cabbage myrosinase followed the well known consecutive step model. Pressure inactivation started at 300 MPa, even at 10 °C, and the consecutive step model effectively described pressure inactivation in the range 300-450 MPa at 10 °C. The combined effects of applying various pressures and temperatures on myrosinase inactivation kinetics were studied in the ranges 35-50 °C and, 100-400 MPa. The inactivation followed first-order kinetics at all of the applied combinations. This study demonstrates that myrosinase from green cabbage is highly susceptible to both thermal and high pressure processing. Furthermore, it is also noted that myrosinase stability during processing appears to vary widely between different Brassica species.     

The possibility of lowering oil content of potato chips by combining atmospheric frying with postfrying vacuum application

Four protocols involving the application of low pressures, either toward the end of frying or after frying, were investigated with the aim of lowering the oil content of potato chips. Protocol 1 involving frying at atmospheric pressure followed by a 3 min draining time constituted the control. Protocol 2 involved lowering of pressure to 13.33 kPa, 40 s before the end of frying, followed by draining for 3 min at the same pressure. Protocol 3 was the same as protocol 2, except that the pressure was lowered 3 s before the end of frying. Protocol 4 involved lowering the pressure to 13.33 kPa after the product was lifted from the oil and holding it at this value over the draining time of 3 min. Protocol 4 gave a product having the lowest oil content (37.12 g oil/100 g defatted dry matter), while protocol 2 gave the product with highest oil content (71.10 g oil/100 g defatted dry matter), followed by those obtained using protocols 1 and 3 (68.48 g oil/100 g defatted dry matter and 52.50 g oil/100 g defatted dry matter, respectively). Protocol 4 was further evaluated to study the effects of draining times and vacuum applied, and compared with the control. It was noted that over the modest range of pressures investigated, there was no significant effect of the vacuum applied on the oil content of the product. This study demonstrates that the oil content of potato chips can be lowered significantly by combining atmospheric frying with draining under vacuum.     

A Comparative Study of the Characteristics of French Fries Produced by Deep Fat Frying and Air Frying

Air frying is being projected as an alternative to deep fat frying for producing snacks such as French fries. In air frying, the raw potato sections are essentially heated in hot air containing fine oil droplets, which dehydrates the potato and attempts to impart the characteristics of traditionally produced French fries, but with a substantially lower level of fat absorbed in the product. The aim of this research is to compare: (1) the process dynamics of air frying with conventional deep fat frying under otherwise similar operating conditions, and (2) the products formed by the 2 processes in terms of color, texture, microstructure, calorimetric properties, and sensory characteristics. Although, air frying produced products with a substantially lower fat content but with similar moisture contents and color characteristics, it required much longer processing times, typically 21 min in relation to 9 min in the case of deep fat frying. The slower evolution of temperature also resulted in lower rates of moisture loss and color development reactions. Differential scanning calorimetry (DSC) studies revealed that the extent of starch gelatinization was also lower in the case of air fried product. In addition, the 2 types of frying also resulted in products having significantly different texture and sensory characteristics.     

Characteristics of Some Fiber Incorporated Cake Preparations and their Dietary Fiber Content

The dietary fibers were mainly isolated from seed hull of field beans (Phaseolus vulgaris), waste pulp of pineapple (Ananas camosus) as well as from whole wheat flour and, the fiber yields were 16.8, 2.0 and 7.0g/100g, respectively. These isolated fibers were included in sponge cake preparation by partially replacing all-purpose flour (maida) by 5% (w/w). Cakes and cake batter were evaluated for pH change, specific gravity, volume, moisture content, and color. The sensory characteristics and volume of the cakes were not altered with the inclusion of isolated fiber in the cake. The sensory quality evaluation showed that the fiber incorporated cakes were acceptable similar to the cake without added fiber. Incorporation of various fibers in the cake preparation increased the total dietary fiber content of the product by 4-6%.     

Poly (o‐anisidine)‐MWCNT nanocomposite: Synthesis,characterization and anticorrosion properties

Poly (o‐anisidine) (POA) ‐ Multi‐walled carbon nanotube (MWCNT) nanocomposites were synthesized by simple in‐situ chemical oxidative technique. Synthesized nanocomposites were characterized for their structure, morphology, thermal and electrical properties. Spectral studies indicated the presence of interactions between poly (o‐anisidine) and the surface of MWCNTs. Conductivity of 2.82 × 10⁻² S cm⁻¹ was obtained for POA‐MWCNT nanocomposite sample containing 21.2% wt. of POA. POA‐MWCNT nanocomposites thus synthesized were incorporated into epoxy based coating formulation and its anticorrosion property was studied. The coatings were also characterized by physicochemical as well as physicomechanical studies. The aim of this study was to develop a facile method for the eco‐friendly synthesis of fillers having better dispersing properties for coating having superior corrosion protective properties. POLYM. COMPOS., 36:1477–1485, 2015. © 2014 Society of Plastics Engineers     

Vacuum-assisted freeze concentration of sucrose solutions

Freeze concentration in a one-step configuration has emerged as an interesting alternative to conventional processes in terms of both the construction and operation of the equipment. For vacuum-assisted freeze concentration reported in this study, vacuum was used as the driving force to remove the concentrated solution from the ice matrix. By applying a vacuum (80 kPa), the efficiency of the freeze concentration was significantly improved over atmospheric conditions showing an evident advantage in terms of the process time (which was one-third of the time required for atmospheric treatments), and a higher recovery of solute, approximately 0.5 kg of sucrose obtained per 1 kg of initial sucrose compared to recovery values ranging from 0.16 to 0.3 kg/kg for atmospheric treatments. A better performance of vacuum-assisted freeze concentration may be attributed to the structure of the frozen phase which acted as a porous solid matrix allowing the flow of the concentrated solution.