Investigation on CAST, CAPN1 and CAPN3 porcine gene polymorphisms and expression in relation to post-mortem calpain activity in muscle and meat quality

This study aimed to detect variability in CAST, CAPN1 and CAPN3 porcine genes and to investigate the effect of CAST and CAPN1 polymorphisms on the activity of native and autolyzed μ-calpain and m-calpain, measured from 1 to 72 h post-mortem in Longissimus dorsi (LD) muscle of 30 pigs. Effects of polymorphisms on meat quality parameter such as pH, color and drip loss were also evaluated. Samples carrying CAST EU137105:g.76,872AA genotype showed higher autolyzed μ-calpain activity 24 and 72 h post-mortem, as well as lower drip loss values. Expression of CAST, CAPN1 and CAPN3 was assessed in LD muscles divergent for shear force. Higher CAST and CAPN3 expression was found in LD with high shear force (P<0.2), confirming a direct role for calpastatin but not for calpain 3 in meat tenderization. In conclusion, CAST gene affected post-mortem activation time of calpain and drip loss.     

Effect of organic complexation on copper accumulation and toxicity to the estuarine red macroalga Ceramium tenuicorne: a test of the free ion activity model

Current water quality criteria (WQC) regulations on copper toxicity to biota are still based on total dissolved (<0.4 μm membrane filter) copper concentrations with a hardness modification for freshwaters. There are however ongoing efforts to incorporate metal speciation in WQC and toxicity regulations (such as the biotic ligand model-BLM) for copper and other metals. Here, we show that copper accumulation and growth inhibition of the Baltic macroalga Ceramium tenuicorne exposed to copper in artificial seawater at typical coastal and estuarine DOC concentrations (similar to 2-4 mg/L-C as fulvic acid) are better correlated to weakly complexed and total dissolved copper concentrations rather than the free copper concentration [Cu2+]. Our results using a combination of competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) measurements and model calculations (using visual MINTEQ incorporating the Stockholm Humic Model) show that copper accumulation in C. tenuicorne only correlates linearly well to [Cu2+] at relatively high [Cu2+] and in the absence of fulvic acid. Thus the FIAM fails to describe copper accumulation in C. tenuicorne at copper and DOC concentrations typical of most marine waters. These results seem to indicate that at ambient total dissolved copper concentration in coastal and estuarine waters, C. tenuicorne might be able to access a sizable fraction of organically complexed copper when free copper concentration to the cell membrane is diffusion limited.     

Mechanical behavior of fuel cell membranes under humidity cycles and effect of swelling anisotropy on the fatigue stresses

The mechanical response of proton exchange membranes in a fuel cell assembly is investigated under humidity cycles at a constant temperature (85 °C). The behavior of the membrane under hydration–dehydration cycles is simulated by imposing a humidity gradient from the cathode to the anode. Linear elastic, plastic constitutive behavior with isotropic hardening and temperature and humidity dependent material properties are utilized in the simulations for the membrane. The evolution of the stresses and plastic deformation during the humidity cycles are determined using finite element analysis for two clamping methods and various levels of swelling anisotropy. The membrane response strongly depends on the swelling anisotropy where the stress amplitude decreases with increasing anisotropy. These results suggest that it may be possible to optimize a membrane with respect to swelling anisotropy to achieve better fatigue resistance, potentially enhancing the durability of fuel cell membranes.     

Manganese dipyridoxyl diphosphate: MRI contrast agent with antioxidative and cardioprotective properties?

Manganese dipyridoxyl diphosphate (MnDPDP) is a contrast agent for magnetic resonance imaging (MRI) of the liver. Aims of the study were to examine if MnDPDP possesses superoxide dismutase (SOD) mimetic activity in vitro, and if antioxidant protection can be demonstrated in an ex vivo rat heart model. Superoxide (*O-2) and hydroxyl radicals (*OH-) were generated in xanthine oxidase and Fenton reactions. Spin adducts with 5,5-dimethyl-1-pyrroline-N-oxide were detected by electron spin resonance spectroscopy. Contractile function and enzyme release were monitored in rat hearts during hypoxia-reoxygenation. Low microM concentrations of MnDPDP and its metabolite Mn dipyridoxyl ethylene-diamine (MnPLED) dismutated *O-2, but showed no activity in Fenton or catalase reactions. MnDPDP 30 microM improved contractile function and reduced enzyme release in rat hearts during reoxygenation. It is concluded that MnDPDP and MnPLED possess SOD mimetic activities and may thereby protect the heart in oxidative stress.     

IP-address lookup using LC-tries

There has been a notable interest in the organization of routing information to enable fast lookup of IP addresses. The interest is primarily motivated by the goal of building multigigabit routers for the Internet, without having to rely on multilayer switching techniques. We address this problem by using an LC-trie, a trie structure with combined path and level compression. This data structure enables us to build efficient, compact, and easily searchable implementations of an IP-routing table. The structure can store both unicast and multicast addresses with the same average search times. The search depth increases as Θ(log log n) with the number of entries in the table for a large class of distributions, and it is independent of the length of the addresses. A node in the trie can be coded with four bytes. Only the size of the base vector, which contains the search strings, grows linearly with the length of the addresses when extended from 4 to 16 bytes, as mandated by the shift from IP version 4 to IP version 6. We present the basic structure as well as an adaptive version that roughly doubles the number of lookups/s. More general classifications of packets that are needed for link sharing, quality-of-service provisioning, and multicast and multipath routing are also discussed. Our experimental results compare favorably with those reported previously in the research literature     

Field test corrosion experiments in Denmark with biomass fuels. Part 1: Straw‐firing

In Denmark, straw and other types of biomass are used for generating energy in power plants. Straw has the advantage that it is a “carbon dioxide neutral fuel” and therefore environmentally acceptable. Straw combustion is associated with corrosion problems which are not encountered in coal‐fired plants. The type of corrosion attack can be directly ascribed to the composition of the deposit and the metal surface temperature. A series of field tests have been undertaken in the various straw‐fired power plants in Denmark, namely Masnedø, Rudkøbing and Ensted. Three types of exposure were undertaken to investigate corrosion: a) the exposure of metal rings on water/air cooled probes, b) the exposure of test tubes in a test superheater, and c) the exposure of test tubes in existing superheaters. Thus both austenitic steels and ferritic steels were exposed in the steam temperature range of 450–600°C. The corrosion rates were assessed by precision measurements of material loss and internal corrosion. The corrosion products and course of corrosion for the various steel types were investigated using light optical and scanning electron microscopy. Corrosion mechanisms are discussed in relation to temperature and deposit composition.     

Efficient production of truncated thermostable xylanases from Rhodothermus marinus in Escherichia coli fed-batch cultures

A cultivation strategy for the production of two truncated thermostable recombinant xylanases (Xyn1deltaN and Xyn1deltaNC) was developed. Fed-batch cultivations of Escherichia coli strain BL21(DE3) with a controlled exponential glucose feed led to high specific production of the recombinant proteins. Addition of complex nutrients (e.g. Tryptone Soya Broth (TSB)) to the media were shown to increase both the specific growth rate during the production phase and the production per cell. The final cell-mass concentration depended on the time of induction in relation to both the feed-start and the expected time at which the cultivation had to be terminated due to oxygen transfer limitations or cell lysis. The gene used for the genetic constructions (encoding Xyn1deltaN and Xyn1deltaNC) was originally isolated from Rhodothermus marinus. Recombinant protein expression was controlled by the T7 lac-promoter and induced in the fed-batch phase at low glucose concentrations by the single addition of either lactose or isopropyl-thio-beta-d-galactoside (IPTG). In lactose-induced cells, the production of recombinant xylanase was delayed for approximately 30 min in comparison with those induced with IPTG, but the specific product levels were comparable at 3 h after induction. At this time, approximately 35% of the intracellular protein content was constituted by recombinant xylanase. Under the cultivation conditions used, production of the shorter deletion derivative (Xyn1deltaNC) led to nonspecific leakage and cell lysis, starting 1.5 or 2 h after induction with IPTG or lactose, respectively. At 3 h after induction, 50% of the produced protein (Xyn1deltaNC) was found in the culture medium. This was not the case for the longer protein (Xyn1deltaN), where only 10% of the xylanase leaked into the medium.     

Influence of low molecular weight lactic acid derivatives on degradability of polylactide

The presence of low molecular weight lactic acid derivatives in films enhanced the degradability of polylactide in a biotic medium. Two different biotic and abiotic series were investigated. The films used for the first abiotic and biotic series (a‐1 and b‐1 films) initially contained some lactic acid and lactoyl lactic acid, while the films used for the second abiotic and biotic series (a‐2 and b‐2 films) did not originally contain them. The b‐1 films decreased in molecular weight during 3 weeks in the biotic medium, while no molecular weight decrease was seen in the a‐1 films aged in a corresponding abiotic mineral medium. The molecular weight for the a‐2 and b‐2 films without lactic and lactoyl lactic acid remained almost constant. Scanning electron microscopy micrographs showed a larger amount of bacteria and fungi growing on the surface of b‐1 films compared to b‐2 films; thus, the presence of easily assimilated lactic acid and lactoyl lactic acid in the films improved the initial growth of microorganisms on the film surfaces. Gas chromatography and mass spectrometry analysis showed that lactic acid and lactoyl lactic acid were rapidly assimilated from the films aged in a biotic medium. New degradation products (e.g., ethyl ester of lactoyl lactic acid, acetic acid, and propanoic acid) were formed during aging in a biotic medium. Acetic acid and propanoic acid were formed as intermediate degradation products during the initial stages, but they were no longer detected after prolonged aging. The concentration of the ethyl ester of lactoyl lactic acid increased with aging time. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 228–239, 2000     

PY‐GC/MS an effective technique to characterizing of degradation mechanism of poly (L‐lactide) in the different environment

The biotic and abiotic degradation of poly (L‐lactide) (PLLA) has been studied with pyrolysis gas chromatography mass spectrometry (Py‐GC‐MS). A mixed culture of compost micro‐organisms was used as the biotic medium. Size‐exclusion chromatography (SEC), gas chromatography‐mass spectrometry (GC‐MS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were utilized to monitor the degradation and degradation mechanism. Differences in pH, molecular weight, surface structure, and degradation mechanisms were noted between sample aged in biotic and abiotic medium. Using fractionated Py‐GC‐MS at 400 and 500°C, acetaldehyde, acrylic acid, lactoyl acrylic acid, two lactide isomers, and cyclic oligomers up to the pentamer were identified as thermal decomposition products of PLA as well as some other not completely identified products. The ratio of meso‐lactide to L‐lactide was lower in the sample aged in the biotic media than the abiotic media. This is a result of the preference of the micro‐organisms for L‐form of lactic acid and lactoyl lactic acid rather than the D‐form that in turn influences the formation and the amounts of meso and D,L‐lactide during the pyrolysis. Based on SEM micrographs, it was shown that degradation in the biotic medium proceeded mainly via a surface erosion mechanism, whereas bulk erosion was the predominant degradation mechanism in the abiotic medium. The SEC and Py‐GC‐MS data indicate that degradation was faster in the biotic than in the abiotic sample. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2369–2378, 2000