The significance of the activity of glycogen debranching enzyme in glycolysis in porcine and bovine muscles

The purpose of the study was to examine the activity of glycogen debranching enzyme, GDE, in porcine and bovine muscles differing in rate of contraction and oxidative capacity. The activity of GDE, the activity of phosphorylase, total glucose content, lactate content and pH were measured from meat samples taken 35min post-mortem and ultimate pH 24 or 48h post-mortem. Both GDE and phosphorylase are needed for the complete degradation of glycogen. In porcine muscles the activities of these glycogen degrading enzymes were higher than in bovine muscles. The activities were increasing with the increasing fast twitch and glycolytic character of a muscle of a given species. However, the increase in the activity of phosphorylase was greater than the increase in the activity of GDE. It was concluded that the GDE may restrict the rate of glycolysis in fast twitch muscles.     

Extended frequency-band-decomposition sigma–delta A/D converter

Parallelism can be used to increase the bandwidths of ADC converters based on sigma–delta modulators. Each modulator converts a part of the input signal band and is followed by a digital filter. Unfortunately, solutions using bandpass sigma–delta modulators are very sensitive to the position of the modulators’ central frequencies. This paper shows the feasibility of a frequency-band-decomposition (FBD) ADC using continuous time bandpass sigma–delta modulators, even in the case of large analog mismatches. The major benefit of such a solution, called extended-frequency-band-decomposition (EFBD) is its low sensitivity to analog parameters. For example, a relative error in the central frequencies of 4% can be accepted without significant degradation in the performance (other published FBD ADCs require a precision of the central frequencies better than 0.1%). This paper will focus on the performance which can be reached with this system, and the architecture of the digital part. The quantization of coefficients and operators will be addressed. It will be shown that a 14 bit resolution can be theoretically reached using 10 sixth-order bandpass modulators at a sampling frequency of 800 MHz which results in a bandwidth of 80 MHz centered around 200 MHz (the resolution depends on the effective quality factor of the filters of the analog modulators).     

Chiral-selective growth of single-walled carbon nanotubes on stainless steel wires

Single-walled carbon nanotubes (SWCNTs) were successfully grown on calcined stainless steel wires at 700 °C using CO as the carbon source. By contrast, the raw stainless steel wires produced only necklace-like multi-walled carbon nanotubes. Photoluminescence spectroscopy studies showed that SWCNTs grown from calcined stainless steel have a narrow diameter distribution and a high chiral selectivity of (6,5) nanotubes. The pre-growth heat treatment of the stainless steel leads to formation of iron and chromium oxides. The reduction of iron oxide results in formation of Fe nanoparticles which, anchored by chromium oxide, account for the chiral-selective growth of SWCNTs.     

Carcass and meat quality traits of four different pig crosses

The study compared properties of Finnish Landrace × Yorkshire crossbred sows mated with Finnish Landrace (FL), Norwegian Landrace (NL), Norwegian Duroc × Norwegian Landrace (NDL), or Swedish Hampshire (SH) boars. The focus was to study the cross-sectional area of loin, cross-sectional area and number of muscle fibres, loin colour and pH value as well as the ratio of water to protein in the loin.The four studied crosses were quite similar having only small differences in carcass and meat quality. The carcass lean content was the lowest in NDL. The loins of FL and NL were longer than the loins of NDL and of SH. The cross-sectional area of loin was the largest in SH. The loin of FL was lighter in colour and the loin of SH was redder than the loins of the other crosses studied. The protein content was lower and the ratio of water to protein higher in loin of SH than in the other crosses.     

Toughening effect of cellulose nanowhiskers on polyvinyl acetate: Fracture toughness and viscoelastic analysis

The toughening effect of cellulose nanowhiskers (CNWs) on modified polyvinyl acetate (PVAc) was analyzed with the help of morphology, relaxation, and creep behavior. The CNWs together with bound moisture at the matrix/whisker interfaces resulted in significant improvement in resistance to crack initiation and propagation. The magnitude of plastic deformation of the nanocomposites was higher than that of the neat PVAc. The relaxation temperature decreased, while the width of the damping peak increased with increasing CNW and moisture contents. The results from creep modeling showed that the instantaneous elastic modulus first increased and then decreased with the addition of CNWs, while the time‐dependent elasticity and viscosity decreased. The results suggested that the reinforcing effect of the CNWs was overwhelmed by the plasticizing effect of the bound moisture. Furthermore, low concentrations of CNWs significantly improved the fracture toughness of PVAc at the minor cost of strength, stiffness, and creep resistance. In this article, we present a novel approach to studying the toughening effect of CNWs on polymers using fracture tests and viscoelastic modeling. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Brandschutz – Dokumentation einer Entwicklung

Fire safety – documentation of a development. Until the end of the 1970s, structural fire safety was the main objective of fire test institutes, and practical fire design was simply derived by the application of tables for the determination of fire resistance times of structural members. Starting in 1980, a new approach was initiated by Bub et al. in Germany and Europe and supported by international bodies such as CIB and scientific societies such as JCSS. Following further developments in Europe, the basics of Eurocode fire safety parts EC 1 to 6 were laid down between 1980 and 1994. Since 2006, Hosser made a significant contribution in this field with the publication of vfdb‐Leitfaden in Germany. This paper provides a brief overview of the beginning, development and significant contributions in this field during recent years.     

Binary, ternary and quaternary silicates of CaO, BaO and ZnO in high thermal expansion seals for solid oxide fuel cells studied by high-temperature X-ray diffraction (HT-XRD)

Gas-tight seals based on glasses suitable for joining of materials with high thermal expansion coefficients are for example required for solid-oxide fuel cells. If these seals are to be used at high temperatures, they can only be fabricated from glasses which enable the crystallization of phases with high thermal expansion coefficients. This paper reports on some components from systems suitable for high thermal expansion seals: binary calcium silicates, CaSiO₃, Ca₃Si₂O₇ and Ca₂SiO₄ zinc silicates, Zn₂SiO₄, ternary silicates of BaO, CaO and ZnO, BaCa₂Si₃O₉, Ca₂ZnSi₂O₇, and one quaternary silicate, Ba₂CaZn₂Si₆O_17, studied by high-temperature X-ray diffraction. Only CaSiO₃, Ca₃Si₂O₇ and BaCa₂Si₃O₉ exhibit thermal expansion coefficients in the range suitable for high thermal expansion seals of 11.2-11.8 × 10⁻⁶ K⁻¹ (100-800 °C). The thermal expansions strongly depend on the respective crystallographic axis. The coefficient of thermal expansion of a sealing glass is not only affected by the thermal expansions of the crystalline phases, but also by that of the residual glassy phase as well as by the elastic properties. The phase formation should carefully be controlled also with respect to aging.     

Glycogen debranching enzyme and some other factors relating to post‐mortem pH decrease in poultry muscles

The objective of this study was to investigate the activity of glycogen debranching enzyme (GDE, EC 3.2.1.68) in chicken pectoralis superficialis (PS) and quadriceps femoris (QF) muscle post‐mortem. In addition, some other factors relating to pH decrease, such as the activity of glycogen phosphorylase (EC 2.4.1.1) and glycolytic potential were studied. Enzyme activities, glycogen content and lactate content were measured in Ross breed broiler chicken muscles obtained 25 min after stunning. An interesting discrepancy in the activities of the two glycogen degrading enzymes, GDE and phosphorylase, between muscles was found. In light PS muscle, phosphorylase activity was higher (P < 0.001), but GDE activity was lower (P < 0.001) than in dark QF muscle. Buffering capacity and glycolytic potential were higher in PS muscle than in QF muscle. The possible need for high buffering capacity and low GDE activity in PS muscle to protect living muscle from rapid pH decrease was discussed. GDE, together with glycolytic potential, accounted for 40% of the variation in ultimate pH in QF muscle and 61% in PS muscle. Considering the low activity of GDE together with the high activity of phosphorylase found in both muscles, the results of the present study support the hypothesis that GDE may restrict the rate of glycogen degradation. Copyright © 2006 Society of Chemical Industry     

Activity of porcine muscle glycogen debranching enzyme in relation to pH and temperature

The activity of glycogen debranching enzyme (GDE) was studied in relation to pH value and temperature in porcine masseter and longissimus dorsi muscles. A glycogen limit dextrin was used as the substrate for GDE, and the enzyme was derived from raw meat extracts. In both muscles, the pH only weakly affected the activity of GDE at the pH values found in carcasses post-slaughter. However, the activity of GDE decreased strongly (P<0.001) when the temperature decreased from values of 39 and 42 °C, found just after slaughter to values of 4 and 15 °C. In both muscles the activity of GDE began to fall at temperatures below 39 °C and was almost zero when the temperature decreased to below 15 °C. Thus, the activity of GDE may control the rate of glycogenolysis and glycolysis, but does not block rapid glycolysis and pH decrease when the temperature is high. This may be important in PSE meat, where the pH decreases rapidly at high temperatures, but rapid cooling could limit the activity of GDE and thus glycogenolysis. As expected, GDE was more active in the light longissimus dorsi muscle than in the dark masseter muscle.