Genetic diversity of ivory shell (Babylonia areolata) in Taiwan and identification of species using DNA-based assays

For better traceability of seafood products in Taiwan, we need to effectively test product quality during the processes of identification of seafood species. The aim of this study was to analyse gene diversity and the methods of identification of high-value seafood, ivory shell (Babylonia areolata), on the Penghu Island in Taiwan using molecular marker technology and to build a relevant molecular database. Thirty-three samples of B. areolata and the samples of 5 other Babylonia species, including Babylonia feicheni, Babylonia spirata spirata, Babylonia perforata and Babylonia formosae formosae, from cultivation and from the wild were tested using the inter-simple sequence repeat (ISSR) method, mitochondrial DNA analysis, PCR-single-strand conformation polymorphism (PCR-SSCP) and PCR-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that the primers ISSR3, ISSR7 and ISSR13 of the ISSR method and cytochrome C oxidase subunit 1 (coxI) gene analysis have a good discriminatory power in inter-species and intra-species tests. In conclusion, ISSR, PCR-DGGE and PCR-SSCP with coxI analysis can be used for the screening and identification of B. areolata species. Furthermore, these molecular methods could be useful for the identification of other types of seafood.     

Carotenoids in crabs from marine and fresh waters of India

Quantitative and qualitative distribution of carotenoids in meat and shell of major marine crab (Charybdis cruciata) and fresh water crab (Potamon potamon) from Indian waters was assessed. The total carotenoid content was low in both species of crabs analysed, highest being 11.0 μg/g in shell of marine crab. Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) of carotenoid extracts indicated that the marine crab contained astaxanthin and its esters as major carotenoids and zeaxanthin was major carotenoid in fresh water crab extract. Astaxanthin and its esters contributed 67.6 and 65.5 g/100 g of total carotenoids in meat and shell of marine crab. The zeaxanthin content (g/100 g) in the carotenoid extract of meat and shell of fresh water crab was 42.0 and 74.8 of total carotenoids. The carotenoid extracts from both the crabs had higher level of unsaturated fatty acids. Oleic acid (C18:1) and palmitoleic acid (C16:1) were the predominant unsaturated fatty acid in carotenoid extract from meat of marine and fresh water crab, respectively. In the carotenoid extract from shell, eicosenoic acid (C20:1) in marine crab and linolenic acid (C18:3) in fresh water crab were the major unsaturated fatty acids.     

Engineered clostridial [FeFe]-hydrogenase shows improved O2 tolerance in Chlamydomonas reinhardtii

Hydrogenase intolerance to oxygen remains a critical hurdle on the road to photosynthetic hydrogen production for sustainable energy demands. Although the engineering of the intrinsic oxygen tolerance mechanism of hydrogenase using mutagenesis is an ambitious approach, recent in-vitro studies reported a novel and improved synthetic [FeFe]-Hydrogenase variants. To corroborate these findings in-vivo, we expressed either an engineered variant or its cognate wild type enzyme in the chloroplast genome of Chlamydomonas reinhardtii. We characterized their activity using a customized photosynthetic hydrogen production in-vivo assay to test whether the improved variant could maintain a greater fraction of its activity following oxygen exposure. We found that the mutated variant exhibited a superior oxygen tolerance while persevering its photosynthetic performance in terms of hydrogen production yield. Importantly, we show for the first time that this approach can potentially address the inherent O₂ sensitivity of [FeFe]-Hydrogenases for photosynthetic hydrogen production.     

Nutritional properties and phenolic content of a bakery product substituted with a mango (Mangifera indica) ‘Ataulfo’ processing by-product

Wheat flour and cane sugar were partially substituted (50 and 75%) by a mango-processing by-product (MPB) as an added-value food ingredient in muffins. Their sensory analysis, chemical composition, antioxidant activity and in vitro starch hydrolysis properties were studied. Sensory analysis showed statistically significant difference (p < 0.05) between control and muffins 75% MPB substituted level (p < 0.05) with the highest score. Proximate analysis revealed that muffins substituted with MPB had significantly (p < 0.05) higher moisture, ash, soluble, insoluble and total indigestible fraction contents but lower total soluble carbohydrates and available starch contents than a non-substituted (control) muffin. Total soluble polyphenol (TSP) content increased about three times (from 1.86 to 5.36 g GAE/100 g dw) with MPB substitution. Chlorogenic, caffeic, gallic, hydroxycinnamic and ferulic acids were identified as major TSP. Muffins with MPB, exhibited better antioxidant properties (104.0 to 108.5 μmol TE/g dw for DPPH assay and 34.1 to 19.1 mmol TE/g dw for FRAP assay) than the control formulation. The presence of high phenolic and insoluble indigestible fraction contents, which may be responsible of the lower rate of starch hydrolysis observed in muffins prepared with MPB, might modulate the postprandial glucose response in vivo. MPB may be used as an ingredient in foods with add-value with potential health-promoting features, besides providing a solution to the environmental problems associated with the disposal of mango by-products.     

Determination of the potential of cyanobacterial strains for hydrogen production

Hydrogen (H₂) is a renewable, abundant, and nonpolluting source of energy. Photosynthetic organisms capture sunlight very efficiently and convert it into organic molecules. Cyanobacteria produce H₂ by breaking down organic compounds and water. In this study, biological H₂ was produced from various strains of cyanobacteria. Moreover, H₂ accumulation by Synechocystis sp. PCC 6803 was as high as 0.037 μmol/mg Chl/h within 120 h in the dark. The wild-type, filamentous, non-heterocystous cyanobacterium Desertifilum sp. IPPAS B-1220 was found to produce a maximum of 0.229 μmol/mg Chl/h in the gas phase within 166 h in the light, which was on par with the maximum yield reported in the literature. DCMU at 10 μM increased H₂ production by Desertifilum sp. IPPAS B-1220 by 1.5-fold to 0.348 μmol H₂/mg Chl/h. This is the first report on the capability of Desertifilum cyanobacterium to produce H₂.     

Study of interactions in carbon nanotubes systems by using Raman and SERS spectroscopy

We present results obtained on carbon nanotube systems by means of Raman scattering and surface enhanced Raman scattering (SERS). Such systems consist of single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs), or polymer/nanotubes composites. In particular, we have focused our studies on the interactions taking place in these compounds which lead to an upshift of the radial breathing mode (RBM) in the case of SWNTs, either when they are arranged in bundles or embedded in polymers. Similar calculations has allowed us to interpret the low frequency Raman modes observed in purified MWNTs. We show that they come from the RBM of individual tubes. From intensity calculations performed to simulate Raman spectra, we demonstrate the importance of two experimental parameters, namely the diameter of internal tubes and the number of shells which constitute the MWNTs, such parameters being extracted experimentally from high resolution transmission electron microscopy images.     

First-principle study of the effects of Nb and Ti doping on the dehydrogenation properties of Ca(BH4)2

The electronic structures of Ca(BH₄)₂ and Ca(BH₄)₂-M (M = Ti or Nb) are studied by first principles density functional theory calculations, and the dehydrogenation mechanism of Ti, Nb doping is also intensively investigated. The formation energy of dopants suggests that both Ti, Nb tend to occupy the interstitial sites. The electronic structure analysis indicates that the interactions of Nb (Ti) and atoms in [BH₄] groups generate intermediate phases which are conducive to the decomposition of Ca(BH₄)₂. The electronegativity calculation and Bader analysis also indicate Nb and Ti have good catalytic behaviors. By analyzing electron localized functions, the calculations indicate that [BH₄] groups restructure after Ti or Nb is doping, and the catalytic function of Ti is weaker than that of Nb. The calculated results are consistent with catalytic dehydrogenation experiments of Ca(BH₄)₂.     

Tribological properties of selected PVD coatings when slid against ductile materials

In this paper, a physical vapour deposited (PVD) deposited TiB₂ coating is compared in dry sliding with commercial PVD titanium nitride (TiN), titanium aluminium nitride (TiAlN) and titanium carbonitirde (TiCN) as to frictional properties and tendency of counter material pick-up. The aim is to investigate if the superior behaviour of the TiB₂ coating experienced in severe sliding applications against aluminium alloys can be extended to other materials with a similarly poor tribological characteristics.A new tribological test for sliding contact has been used. The test configuration involves two crossed elongated cylindrical test specimens which are forced to slide axially against each other at a constant sliding speed and a gradually increasing normal load, while recording the friction. The evaluation is performed by correlating the friction history with the width, topography and composition of the sliding tracks as detected by optical and scanning electron microscopy.Coated cemented carbide (CC) test cylinders have been slid against cylinders of a Ti alloy (Ti–6Al–4V), an Al alloy (Al 7075) and Inconel 718. It was shown that the TiB₂ surface displayed superior friction and anti-sticking properties, when tested against the aluminium alloy. Against the Ti and Inconel alloys no major difference between the coatings could be found. Instead, it is concluded that the friction coefficient is determined by the plastic properties of the counter material since a complete transfer layer instantly builds up on the coating.It proved possible to estimate the friction force from the width of the sliding tracks, the Vickers hardness of the counter material and simple plastic considerations. This estimation also verifies the unexpectedly low friction of all coatings against the Ti alloy.     

Superstructures exhibited by oxides of the aurivillius family, (Bi2O2)2+ (An−1BnO3n+1)2−

Bi₅Ti₃FeO₁₅ and Bi₇Ti₃Fe₃O₂₁ which are n=4 and n=6 members of the family of oxides of the general formula (Bi₂O₂)²⁺(A_n−1B_nO_3n+1)²⁻ show unusual superstructures, possibly due to cation ordering.     

NUMERICAL SIMULATION OF THE EFFECTS OF WEIGHT SYSTEM ON THE HYDRODYNAMIC BEHAVIOR OF 3-D NET OF GRAVITY CAGE IN CURRENT

In this article, a model of 3-D net is set up by using lumped mass method. Model test results made by Lader and Enerhaug are cited to verify the numerical model. The aim of this paper is to investigate the effects of weight system on the hydrodynamic behavior of 3-D net of gravity cage in current. Using the 3-D net model, with different styles and masses of weight system, hydrodynamic behavior of gravity cage net in current is simulated. In this article, two styles of common weight system are used, which include: (1) sinker system , (2) bottom collar-sinker system. Under each style, three different masses of weight system are adopted. The numerical results indicate that the bottom collar-sinker system is practically feasible in improving the cage net volume deformation. Results of this study will give references for better knowledge of hydrodynamic behavior of gravity cage.