Nucleotide breakdown products of seer fish (Scomberomorus commerson) steaks stored in O2 scavenger packs during chilled storage

Freshness of seer fish (Scomberomorus commerson) steaks packed with and without O₂ scavenger was assessed by sensory and chemical methods. O₂ scavenger used in the present study reduced the O₂ level in the pack to less than 0.01% within 24 h. Samples in air packs were sensorily acceptable only up to 12 days compared to 20 days in O₂ scavenger packs. TVB-N levels were 37 and 34 mg N₂/100 g and TMA-N levels were 16.4 and 15.2 mg N₂/100 g on the day of sensory rejection for air and O₂ scavenger packs, respectively. IMP decrease and Hx increase was significantly (P < 0.05) faster in air packed samples compared to O₂ scavenger packs. On sensory rejection day, the average K, Ki, P and H values were 63–65%, Fr value was 34% and G value was 178% for O₂ scavenger packed samples compared to 81%, 18% and 443% for air packed samples, respectively.Industrial relevanceThe O₂ scavenger is an innovative active packaging technique, which is highly effective in reducing the O₂ present inside the pack. This can be used in place of traditional vacuum packaging for extending the shelf life of fish products, which reduces the use of vacuum packaging equipments thereby making the process cost effective.     

CO2 based natural circulation loops: New correlations for friction and heat transfer

Results obtained from CFD analysis of 3-dimensional natural circulation loops (NCL) that employ carbon dioxide and water as loop fluids are presented for various isothermal wall temperatures of source and sink in the range of 278–341 K. Such a temperature range would be useful in various heat transfer applications of NCL, e.g. air conditioning, solar collectors, extraction of geothermal energy, etc. For the same wall temperature and geometrical parameters, comparison is made between CO₂ and water in terms of heat transfer rate. Water is considered at atmospheric pressure whereas CO₂ is either in subcritical (liquid) or supercritical state. Liquid CO₂ exhibits very high heat transfer rate, approximately seven times higher than water, whereas performance of supercritical CO₂ depends on the operating pressure and temperature. Effect of loop operating pressure on the system performance is also investigated. Results show that near pseudo-critical region, CO₂ yields very high heat transfer rate, approximately seven times higher than water. Results also show that, due to the presence of bends and local buoyancy effects, fluid parameters such as local velocity and temperature vary in all three dimensions. Validation of simulation results against experimental results reported in the literature with respect to modified Grashof number (Gr_m) and Reynolds number (Re) exhibit good agreement. Additionally, new correlations are proposed for Re in terms of Gr_m, friction factor (f) in terms of Re, and Nusselt number (Nu) in terms of Re and Prandtl number (Pr).     

Environmental radioactivity studies in the proposed Lambapur and Peddagattu uranium mining areas of Andhra Pradesh, India

The present work was aimed at the establishment of baseline radioactive data in the proposed Lambapur and Peddagattu uranium mining areas in the Andhra Pradesh state, India. The background concentrations of naturally occurring radioactivity in the near-surface soils of the study areas were estimated and the results were analysed. The (238)U concentration in the near-surface soil of the study area was found to vary from 100 to 176 Bq kg(-1), with a mean of 138±24 Bq kg(-1). (232)Th in the study area soils was found to vary between 64 and 116 Bq kg(-1), with a mean of 83±15 Bq kg(-1). The (40)K concentration was found to vary between 309 and 373 Bq kg(-1), with a mean of 343±20 Bq kg(-1). The mean natural background radiation levels were also measured with thermoluminescence (TL) dosimetry technique and with a μR-survey meter, in the villages of the study area. Dose rates measured by TL are found to vary from 1287 to 3363 μGy y(-1), with a mean of 2509 ± 424 μGy y(-1). The dose rates measured in the same villages with a μR-survey meter were found to be in the range of 1211-3255 μGy y(-1), with a mean of 2524 ± 395 μGy y(-1). The mean radiation levels in the study area are found to be relatively high when compared with (Indian) national and international averages. Correlations among radon, thoron and gamma dose rates were found to be poor. The pre-operational data produced in this work will be useful for comparison with future radiation levels during the proposed uranium mining operations.     

Preparation and characterization of biocompatible carbon electrodes

Electron transfer in microbial fuel cell and biosensors could be facilitated through high conductive materials with enhanced active surface area and appropriate redox potential suited to microbial metabolism. In the first strategy based on bulk doping, graphite/epoxy composite electrode (GECE) bulk was modified with six types of metal ion which were prepared through a wet impregnation procedure. In the second strategy, immobilization of redox dye on carbon cloth and graphite sheet was carried out using N,N′-dicyclohexylcarbodiimide for surface modification. Crystallinity, morphology, surface chemistry and electrochemical properties of all modified electrodes were investigated. Influence of redox behavior of electrodes suited to microbial metabolism and conducive to biofilm formation have been examined. It was observed that the Fe³⁺ doped GECE surfaces exhibited significantly high biofilm formation of 1.10(±0.18) × 10⁷ CFU/cm² as compared to other dopants. The microbial growth on the carbon cloth electrode and carbon fiber reinforced plate were found to be less (2.6(±0.97) × 10⁴, 4.8(±1.8) × 10³ CFU/cm² respectively) compared to GECEs.     

The role of functionalized carbon nanotubes in a PA6/LCP blend

Multi-walled carbon nanotubes (MWCNTs) were carboxyl-functionalized in order to improve their dispersion in a polymer matrix. The carboxyl-functionalized MWCNTs (i.e., MWCNT-COOH) were added into a blend matrix consisting of polyamide 6 (PA6) and liquid crystalline polymer (LCP) (PA6:LCP = 80:20 in weight) to make ternary composites. The effects of MWCNT-COOH on the rheological, physical, morphological, thermal, mechanical, and electrical properties of the ternary composites have been examined systematically. The dispersion of MWCNTs in the polymer matrix and their interactions with the polymers (i.e., PA6 and LCP) were found to be the most important factors affecting all properties. The functionalization of MWCNTs resulted in the significant improvement in their dispersion in the polymer matrix and largely enhanced the interactions of MWCNTs with the polymer matrix. The functionalized MWCNTs acted not only as reinforcement fillers but also as a compatibilizer that could enhance the interfacial adhesion between PA6 and LCP. Interestingly, the packing density of the polymer matrix was greatly increased by adding MWCNT-COOH.     

Optimal machining conditions for turning Ti-6Al-4V using response surface methodology

Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work
hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force (F_z) and surface roughness (R_a). In the present work, the performance of PVD/TiAlN coated carbide inserts was investigated using response surface methodology (RSM) for turning Ti-6Al-4V. The effects of process parameters such as speed (v), feed (f), depth of cut (d) and back rake angle (γ_y) on F_z and R_a were investigated.
The experimental plan used for four factors and three levels was designed based on face centered, central composite design (CCD). The experimental results indicated that F_z increased with the increase in d, f and decreased with the increase in v and γ_y, whereas Ra decreased with the increase in v and γ_y, and increased with d and v. The goodness of fit of the regression equations and model fits (R ²) for F_z and R_a were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model.     

Near-Field Scanning Nanophotonic Microscopy—Breaking the Diffraction Limit Using Integrated Nano Light-Emitting Probe Tip

We introduce a novel scanning ldquonanophotonicrdquo microscope through monolithic integration of a nanoscale LED (Nano-LED) on a silicon cantilever. We review two recent trends of incorporating miniature light sources on the scanning probes for near-field scanning optical microscopy: one is to attach fluorephores at the tip to define a small light source, while the other is to integrate an LED and a nanometer aperture into scanning probes, based on silicon microfabrication techniques. The creation of Nano-LED combines the advantages of previous two approaches: no external sources are required and the reduction of the light source size directly leads to resolution improvement. Two types of Nano-LEDs have been successfully demonstrated utilizing nanofabrication and microelectromechanical systems technologies: 1) formation of thin silicon dioxide light-emitting layer between heavily doped p + and n+ silicon layers created by a focused ion beam and 2) electrostatic trapping and excitation of CdSe/ZnS core-shell nanoparticles in a nanogap. We employed these probes into a standard near-field scanning and excitation setup. The probe successfully measured optical as well as topographic images of chromium test patterns with imaging resolutions of 400 and 50 nm, respectively. In addition, the directional resolution dependence of the acquired images suggests the size and shape of the light source. To our knowledge, these results are probably the first successful near-field images directly measured by such tip-embedded light sources. With the potential emission capability from near UV to IR and additional mass producibility, the nanophotonic microscope presents exciting opportunities in near-field optics, integrated circuit technology, nanomanufacturing and molecular imaging, and sensing in biomedicine.     

Zingiber officinale extract exhibits antidiabetic potential via modulating glucose uptake, protein glycation and inhibiting adipocyte differentiation: an in vitro study

BACKGROUND: Ginger, the rhizome of Zingiber officinale Roscoe (Zingiberaceae), a perennial herbaceous plant is native to Southern Asia. Study was aimed to evaluate antioxidant and antidiabetic potential of ginger extract and its characterization. Possible mode of action to elicit antidiabetic activity was also evaluated. METHODS AND RESULTS: Ethyl acetate extract of ginger (EAG) was evaluated for its antioxidant activity in terms of DPPH radical scavenging potential with an IC₅₀ value of 4.59 µg/ml. Antidiabetic activity of EAG was evaluated by estimating antiglycation potential (IC₅₀ 290.84 µg/ml). HPLC profiling of EAG revealed the presence of phenolic components, gingerol and shoagol as major constituents. After determining sub‐toxic concentration of EAG (50 µg/ml), efficacy of extract to enhance glucose uptake in cell lines were checked in L6 mouse myoblast and myotubes. EAG was effective at 5 µg/ml concentration in both cases. Antibody based studies in treated cells revealed the effect of EAG in expressing Glut 4 in cell surface membrane compared to control. CONCLUSION: The antidiabetic effect of ginger was experimentally proved in the study and has concluded that the activity is initiated by antioxidant, antiglycation and potential to express or transport Glut4 receptors from internal vesicles. Copyright © 2012 Society of Chemical Industry