The Effect of Buckwheat Hull Extract on Lipid Oxidation in Frozen‐Stored Meat Products

This study investigated the effect of antioxidants on lipid stability of frozen‐stored meat products. Buckwheat hull extract was used to enrich fried meatballs made from ground pork. During 180‐d storage of meat products, lipid oxidation (peroxide and 2‐thiobarbituric acid reactive substances [TBARS] value) was periodically monitored. The results were compared with butylated hydroxytoluene (BHT). The addition of antioxidants decreased lipid oxidation in stored meatballs. The highest ability to control peroxide and TBARS values was demonstrated for buckwheat hull extract. Moreover, buckwheat hull extract showed a higher 2,2‐diphenyl‐1‐picrylhydrazyl free radical scavenging activity as well as higher Fe(II) ion chelating ability, as compared with BHT. The total content of phenolic compounds are highly correlated to the individual polyphenols in extract of buckwheat hull, among which the following were assayed: 3,4‐dihydroxybenzoic acid, 4‐hydroxybenzoic acid, gallic acid, isovanillic acid and p‐coumaric acid, and flavonoids: isoorientin, quercetin, quercetin 3‐d ‐glucoside, rutin, and vitexin. These results indicate that plant extracts can be used to prolong shelf life of products by protecting them against lipid oxidation and deterioration of their nutritional quality.     

Reduced and total glutathione and cysteine profiles of citrus fruit juices using liquid chromatography

A liquid chromatography assay for the determination of different species of glutathione and cysteine in fruit juices is described. The method is based on derivatization of thiols with 2-chloro-1-methylquinolinium tetrafluoroborate followed by chromatographic separation and UV-absorbance detection and quantitation. The method is linear in wide range of concentrations with a regression coefficient better than 0.99. The detection limits for glutathione and cysteine were 0.1 and 0.05 μmol L⁻¹, respectively. Analytical recovery and the imprecision for both analytes were in the ranges 99.1–101.3% and 2.0–9.0%, respectively. The method was successfully applied to analysis of orange and grapefruit juices for reduced and total glutathione and cysteine.     

Assessment of alkali–silica reaction damage through quantification of concrete nonlinearity

A newly developed nondestructive evaluation technique, Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS), is applied to concrete specimens in an ongoing assessment of aggregate alkali reactivity during standard concrete prism testing. NIRAS measures the nonlinearity in a specimen caused by the inception and growth of microcracks throughout the sample and debonding at the aggregate/cement interface. NIRAS is used to exploit the nonlinear effect of excitation amplitude dependent resonance frequency changes, which are related to nonlinearity measurements of concrete samples cast with aggregates of varying reactivity. To relate microstructural changes to changes in nonlinearity and expansion, sample characterization is performed with uranyl-acetate staining. The results demonstrate the utility of NIRAS for not only assessing the potential for ASR under standardized test conditions, but for more general damage characterization in concrete and assessment of “job mixtures.” NIRAS can distinguish reactive from nonreactive aggregates without ambiguity, as supported by sample characterization results.     

Properties of refrigerated ground beef treated with potassium lactate and sodium diacetate

BACKGROUND: Ground meat is product that perishes easily and therefore various preservatives are applied to prolong its shelf life. The aim of this study was to investigate the effect of potassium lactate and sodium diacetate (Protec K‐DI preparation) on general proteolytic activity, protein degradation, texture, colour and water‐holding capacity of vacuum‐packaged ground beef. RESULTS: The activity of endogenous proteolytic enzymes, and hence the rate of protein hydrolysis changed significantly (P < 0.05) during refrigerated storage. The proteolysis was more intensive in the meat with the preservative than in a control sample. According to the results of SDS‐PAGE, the level of myosin in ground beef decreased with increasing storage time, whereas the preservative did not have a significant effect (P > 0.05) on these changes. However, its impact was the most significant in the case of tropomyosin and troponin T content, as well as changes of 30 kDa protein content. The preservative as well as the increase in storage time influenced an increase in content of polypeptides, peptides and some amino acids in the samples, and had an inhibiting effect on unfavourable changes in ground beef hardness. The preservative addition allowed the meat to maintain desired meat colour, and the main pigment during refrigerated storage was oxymyoglobin (MbO₂). CONCLUSION: Results showed that the Protec K‐DI preparation can be useful in minced meat production as a good stabiliser of colour and texture despite the increase observed in proteolytic activity after the preservative addition. Copyright © 2007 Society of Chemical Industry     

Mechanical properties of magnetorheological elastomers under shear deformation

In this paper, urethane magnetorheological elastomers (MREs) consisting of carbonyl-iron particles in a polyurethane matrix were studied. The volume fraction of particles was equal to 11.5%. Three types of ferromagnetic particles were used, with average particle size ranging from 1 to 70 μm. The elastic (storage) modulus G′ was measured as a function of angular frequency ω and strength of magnetic field. The measured G′ values were approximated with empirical model. The highest magnetorheological effect has been found for samples with 6–9 μm carbonyl-iron powder. The highest increase in the yield stress is observed for samples with particles aligned at 30° to the magnetic field lines. It has been found that rheological properties strongly depend on the MRE microstructure, in particular on the size/shape of particles and their arrangement. By optimizing the particles size, shape and alignment, the stiffness of MREs has been increased under applied magnetic field.     

Tunneled-cuffed catheter implanted into the accessory hemiazygos vein because of occlusion of the left innominate vein

Hemodialyzed patients are at risk of multiple catheterizations. Nephrologists performing such procedures need to be familiar with congenital and acquired vascular abnormalities. We describe a successful insertion and use of a cuffed-tunneled catheter in a patient with unusual anatomy of the central venous system. Computed tomography angiography revealed thrombosis of the right subclavian vein and bilateral occlusion of innominate veins. The left internal jugular and subclavian veins joined to form a large vessel that drained through the accessory hemiazygos and azygos veins into the superior vena cava. The catheter was implanted through the left internal jugular vein into the accessory hemiazygos vein. The presented case demonstrates that the catheter can be implanted into distended collateral, especially when no other location is possible.     

Hydrogel membranes based on genipin-cross-linked chitosan blends for corneal epithelium tissue engineering

Novel polymeric hydrogel scaffolds for corneal epithelium cell culturing based on blends of chitosan with some other biopolymers such as hydroxypropylcellulose, collagen and elastin crosslinked with genipin, a natural substance, were prepared. Physicochemical and biomechanical properties of these materials were determined. The in vitro cell culture experiments with corneal epithelium cells have indicated that a membrane prepared from chitosan-collagen blend (Ch-Col) provided the regular stratified growth of the epithelium cells, good surface covering and increased number of the cell layers. Ch-Col membranes are therefore the most promising material among those studied. The performance of Ch-Col membranes is comparable with that of the amniotic membrane which is currently recommended for clinical applications.     

Patterning of carbon nanotube structures by inkjet printing of catalyst

The controlled deposition of carbon nanotubes (CNTs) has many potential applications in areas such as microfluidics and field emission arrays. The use of inkjet printing to deposit catalyst offers numerous advantages for these, particularly the ability to print arbitrary patterns at low cost. We use inkjet technology to deposit iron salts, which act as a catalyst from which CNTs are subsequently grown by chemical vapour deposition. In this study, we study the effect of the iron salt concentration on ink viscosity, as well as the printing quality using optical and electron microscopy. We find that the iron salt concentration has a significant effect on the pattern quality and, most importantly, allows for the production of controllable ring-like shapes with feature size smaller than that achievable by the print-head alone. These shapes are the result of a variation of the coffee-stain effect, and could be useful particularly in fabricating microfluidic devices. We show that iron salts are suitable CNT catalysts for deposition by inkjet printing, and that their concentration is crucial both for print quality as well as for the production of novel patterns by making use of the drying behaviour of the ink.     

Nicotine, cotinine, and myosmine determination using polymer films of tailor-designed zinc porphyrins as recognition units for piezoelectric microgravimetry chemosensors

Two electropolymerizable zinc porphyrins with receptor sites tailor-designed for selective recognition of the nicotine, cotinine, or myosmine alkaloids were synthesized. These were 5-(2-phenoxyacetamide)-10,15,20-tris(triphenylamino)porphyrinato zinc(II) 1 and 5-(2,5-phenylene-bis(oxy)diacetamide)-10,15,20-tris(triphenylamino)porphyrinato zinc(II) 2 featuring one and two pendant amide side "pincers", respectively, and three triphenylamine substituents at the meso positions of the porphyrin macrocycles capable of electrochemical polymerization. Thin polymerfilms of these porphyrins served for recognition and the piezoelectric microgravimetry (PM) for analytical signal transduction of a new chemical sensor devised for determination of these alkaloids. The films were deposited by potentiodynamic electropolymerization on the 10 MHz quartz resonators of the electrochemical quartz crystal microbalance (EQCM) without affecting the electronic structure of the porphyrin macrocycles. Under favorable flow injection analysis (FIA) conditions, the alkaloid analytes were determined at the concentration level of 0.1 mM with high sensitivity and selectivity. Affinity toward the analytes of the polymer of 2 was higher than that of 1 due to the higher binding ability offered by two pendant pincers of the former. Because of the selective receptors and PM applied under FIA conditions, the developed procedure offered an alternative to the time-consuming and relatively expensive high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), and gas chromatography mass spectrometry (GC-MS) methods of detection and quantification of these alkaloids.     

Power handling capabilities of superconducting YBCO thin films: Thermally induced nonlinearity effects

We have measured the microwave power dependence of the surface impedance Z_s of YBa₂Cu₃O_x thin films up to very high microwave power levels. Films with different crystal qualities, including one with a bicrystal Josephson junction, were investigated. The experiments included both frequency-domain and pulsed time-domain measurements using a 14 GHz TE₀₁₁ dielectric cavity. Our results demonstrate that the dissipation of heat, generated by rf currents in the superconducting film, contributes to the observed nonlinearities in the surface resistance. The relative extent of this contribution is determined primarily by the film quality. A simple Fabry-Perot resonator model, combined with a cavity heat transfer model, was used to analyze the effects of such nonlinearities on the electromagnetic response of the dielectric cavity to a pulsed input signal.