Comparison of hydrogen hydrates with existing hydrogen storage technologies: Energetic and economic evaluations

With the development of the hydrogen economy and FCV (fuel cell vehicles), the manner of storing and delivering large quantities of hydrogen arises as a major problem, and increasing research efforts are being targeted to solve this technological issue. Nowadays several hydrogen storage methodologies are available. Technologies are being developed and/or engineered other than the classical compression and liquefaction of hydrogen, which are based on the chemical (metal hydrides, ammonia) and physical (e.g., carbon nanotubes) adsorption of H₂. Also, a novel technology is in progress, which is based on clathrate hydrates of hydrogen. The object of the present work is to evaluate the features and performances of those storing systems with the aim to determine the best available technology throughout the “hydrogen chain”. For each one of the storage solutions presented, we have compared key parameters such as: interaction energy between hydrogen and support, storage capacity, specific energy consumption (SEC). By this work, it is demonstrated that a technology based on clathrate hydrates of hydrogen, while far from being optimized, may be competitive with the other approaches.     

Inactivation effect of an 18-T pulsed magnetic field combined with other technologies on Escherichia coli

The inactivation effect of 18 T pulsed magnetic fields in combination with selected non-thermal technologies was studied on Escherichia coli ATCC 11775. The bacteria were subjected to a treatment of either ultrasound (20 kHz, 70 W, 242 μm), high hydrostatic pressure (207 MPa, 5 min), pulsed electric field (6.25 kV/cm, 5.6 ms), or anti-microbials (Nisin 77.5 mg/l, lysozyme 1 mg/ml) and 50 magnetic field pulses (18 T, 30 μs). No additional inactivation or cell damage due to exposure to the pulsed magnetic field at 42°C was observed.     

Flavonoids from Portuguese heather honey

The flavonoids present in twenty samples of Portuguese heather honey were analysed by reversed-phase HPLC. The flavonoid fraction was purified by a combination of chromatography on Amberlite XAD-2 and Sephadex LH-20 columns. The total amount of flavonoids ranged between 60 and 500 g/100g honey, values which are much smaller than those previously found for Spanish rosemary honey samples (500-2000 g/100 g honey). The main flavonoids present in Portuguese heather honey were the flavanones pinocembrin and pinobanksin and the flavones chrysin and galangin. These analyses showed that all the samples contained a similar flavonoid pattern composed of at least 22 compounds. The most characteristic substances were myricetin, myricetin 3-methyl ether, myricetin 3'-methyl ether and tricetin. These four flavonoids have in common the structural feature of having a trioxygenated ring B (3',4',5'-trioxygenation), this being an attribute not found in the flavonoids detected in any other honey sample of different plant origin analysed so far, suggesting that these substances could probably be used as markers for the botanical origin of heather honey.

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Flavonoide aus portugiesischem Heidehonig

Zusammenfassung Die Flavonoide aus portugiesischem Heidehonig wurden mit der HPLC in reversed-phase-Technik analysiert. Die Fraktionen wurden durch Adsorptionsund Gelchromatographie gereinigt, ihre Gesamtausbeute betrug 60 bis 500 g/100 g Honig. Als Hauptkomponenten wurden Pinocembrin und Pinobanksin (Flavanone) sowie Chrysin und Galangin (Flavone) identifiziert. Alle Proben erhielten ein ähnliches Muster aus mindestens 22 Flavonoiden. Charakteristisch waren Myricitin sowie dessen 3- und 3'-Methylether sowie Tricetin. Derartige Verbindungen wurden bisher in keinem anderen Honig gefunden und eignen sich möglicherweise als Herkunftsnachweis für Heidehonig.

     

Dog rose and pomegranate extracts as agents to control enzymatic browning

To demonstrate that two natural products obtained with minimal processing can be used as antibrowning agents, extracts of dog rose hips and pomegranate arils were assayed for inhibition of tyrosinase and polyphenol oxidase activity. The efficiency of antibrowning activity was evaluated in terms of absorbance and polyacrylamide gel zymograms. In addition to the in vitro studies, melanosis in foods such as artichokes, mushrooms and pear juice was evaluated. The results revealed that dog rose hip extract was more effective than pomegranate aril extract. Moreover, high performance liquid chromatography analysis showed that extracts from both sources had many potential inhibitors of polyphenol oxidase and tyrosinase activity.     

Comparison of reduction in foodborne viral surrogates by high pressure homogenization

With the increasing global spread of human noroviral infections and the emergence of highly virulent noroviral strains, novel inactivation methods are needed to control foodborne outbreaks. High pressure homogenization (HPH) is a novel method that can be applied for foodborne virus reduction in fluids being continuously processed. Our objective in the present study was to compare the titer reduction by HPH between feline calicivirus strain F9 (FCV-F9) and murine norovirus 1 (MNV-1) as surrogates for human noroviruses, and MS2 (single-stranded F-RNA coliphage) and somatic coliphage φX174 (single-stranded DNA) as indicators of fecal contamination. Duplicate experiments with each virus in phosphate-buffered saline were carried out with homogenization pressures of 0, 100, 200, 250, and 300 MPa, with exposure temperatures of 24, 46, 63, 70, and 75°C, respectively, for <2 s. FCV-F9 was found highly susceptible to HPH treatment pressures of 300 MPa, with a reduction of >4.95 log PFU/ml. Lower pressures of 250, 200, and 100 MPa resulted in reductions of 1.61, 0.60, and 0.18 log PFU/ml of FCV-F9, respectively, while MNV-1 was not reduced at these lower pressures. Coliphage φX174 showed no significant reduction at 300 MPa or lower homogenization pressures in comparison with MS2, which did show 3.3-log PFU/ml reduction at 300 MPa. Future studies using juices for industrial application of HPH to determine microbial inactivation with simultaneous retention of sensory and nutritional value of foods are needed.     

An HPLc technique for flavonoid analysis in honey

A new technique for the analysis of flavonoids in honey has been developed. This uses filtration of honey through Amberlite-XAD-2 and purification of the flavonoid fraction by Sephadex LH-20. The flavonoid fraction is then analysed by HPLC. This technique allowed the identification of 16 flavonoids in honey, namely quercetin, kaempferol, 8-methoxykaempferol, quercetin 3-methyl ether, isorhamnetin, kaempferol 3-methyl ether, quercetin 3,3-dimethyl ether, quercetin 3,7-dimethyl ether, galangin, luteolin, apigenin, genkwanin, chrysin, luteolin 7-methyl ether, pinocembrin and pinobanksin. The flavonoids present in ten samples of honey from La Alcarria have been HPLC analysed by this technique. The fact that the flavonoid patterns are very similar, suggests that samples from other areas should be examined in order to assess if this procedure could be useful as an adjunct in studies of the geographical origin of honey.     

Egg white lysozyme purification with a chitin–silica-based affinity chromatographic matrix

A composite biosorbent retaining non-covalently bound chitin in between layers of a silicon oxide matrix was assessed for lysozyme purification from undiluted egg white. The matrix can be shaped with big size and high density, thus allowing its efficient separation from the egg white after the adsorption step. The lysozyme-depleted egg white can follow its usual commercialisation route. A surface area of 142 m²/g and a total pore volume of 0.295 cm³/g were calculated from the nitrogen sorption isotherms. Its water content was 78.3%. The matrix structure is the result of the polysaccharide addition to the polymerisation mixture, which is known to influence the condensation process, leading to a material with characteristic properties. A maximum capacity of 117.1 ± 9 mg lysozyme/g and a dissociation constant of 0.73 ± 0.15 mg/mL were calculated from the Langmuir isotherm. A lysozyme purification batch process from undiluted egg white was developed, where 87% of the lysozyme was removed from the egg white and the matrix was easily recovered by a simple filtration through a strainer. The overall yield of the process was 64% with a purification factor of 20.     

Analytical formulae for electromechanical effective properties of 3–1 longitudinally porous piezoelectric materials

A unidirectional fiber composite is considered here, the fibers of which are empty cylindrical holes periodically distributed in a transversely isotropic piezoelectric matrix. The empty-fiber cross-section is circular and the periodicity is the same in two directions at an angle π/2 or π/3. Closed-form formulae for all electromechanical effective properties of these 3–1 longitudinally periodic porous piezoelectric materials are presented. The derivation of such expressions is based on the asymptotic homogenization method as a limit of the effective properties of two-phase transversely isotropic parallel fiber-reinforced composites when the fibers properties tend to zero. The plane effective coefficients satisfy the corresponding Schulgasser–Benveniste–Dvorak universal type of relations. A new relation among the antiplane effective constants from the solutions of two antiplane strains and potential local problems is found. This relation is valid for arbitrary shapes of the empty-fiber cross-sections. Based on such a relation, and using recent numerical results for isotropic conductive composites, the antiplane effective properties are computed for different geometrical shapes of the empty-fiber cross-section. Comparisons with other analytical and numerical theories are presented.