The question of high- or low-temperature glass transition in frozen fish. Construction of the supplemented state diagram for tuna muscle by differential scanning calorimetry     

Orlien V  Risbo J  Andersen ML  Skibsted LH 《Journal of agricultural and food chemistry》2003,51(1):211-217

The thermal behavior of fresh tuna muscle, rehydrated freeze-dried tuna muscle, and tuna sarcoplasmic protein fraction was studied by three types of differential scanning calorimetry (DSC): conventional DSC, alternating DSC, and sensitive micro-DSC. The relationship between glass transition temperature, T(g), and water content was established. Only a low-temperature glass transition was detected for fresh tuna and freeze-dried tuna rehydrated to high water contents, whereas for sarcoplasmic protein fraction both a low-temperature and an apparent high-temperature glass transition were detected for samples of high water content. Construction of the supplemented state diagrams for whole tuna muscle and for tuna sarcoplasmic protein fraction confirmed the low-temperature transition to be glass transition of the maximally freeze-dehydrated phase. The apparent upper transition of sarcoplasmic protein fraction was shown not to be a glass transition but rather to originate from the onset of melting of ice, and the temperature of this event should be denoted T(m)'. The glass transition temperature and the concentration of the maximally freeze dehydrated tuna muscle are -74 degrees C and 79% (w/w), respectively.  相似文献   

An analytical method for the analysis of tulathromycin, an equilibrating triamilide, in bovine and porcine plasma and lung   总被引：2，自引：0，他引：2  

Gáler D  Hessong S  Beato B  Risk J  Inskeep P  Weerasinghe C  Schneider RP  Langer C  LaPerle J  Renouf D  Bessire A  Español E  Rafka R  Ragan C  Boettner W  Murphy T  Keller D  Benchaoui H  Nowakowski MA 《Journal of agricultural and food chemistry》2004,52(8):2179-2191

Tulathromycin is a novel member of the triamilide class of antibiotics that was developed as a safe and effective single-dose treatment of bovine and porcine respiratory disease. An accurate and precise analytical method was developed for the extraction and measurement of tulathromycin in livestock plasma and lung homogenates. Analytes were solid-phase extracted onto a weak cation exchanger after aqueous dilution of samples and addition of heptadeutero-tulathromycin as an internal standard. Following HPLC with a narrow bore C8 column, quantitative detection of tulathromycin was accomplished by monitoring the transition of a doubly charged precursor ion to a singly charged product ion by tandem mass spectrometry using a triple quadrupole mass spectrometer. Procedures were validated for a dynamic range of 0.1 to 25 ng on column. Observed accuracies were between 90 and 110% of nominal and precision (RSD) varying 7% or less. Response and stability experiments showed that deuterated tulathromycin did not parallel the chemical behavior of tulathromycin. Applicability of the method to livestock studies was tested with plasma and lung samples from cattle and swine dosed with tulathromycin at multiple doses. The results demonstrated that the analytical method performed well in a range of sample concentrations spanning over 3 orders of magnitude and provided dose-exposure relationships for cattle and swine.  相似文献   

Effect of temperature and glassy states on the molecular mobility of solutes in frozen tuna muscle as studied by electron spin resonance spectroscopy with spin probe detection     

Orlien V  Andersen ML  Jouhtimäki S  Risbo J  Skibsted LH 《Journal of agricultural and food chemistry》2004,52(8):2269-2276

The mobility of solutes in frozen food systems (tuna muscle, sarcoplasmic protein fraction of tuna muscle, and carbohydrate-water) has been studied using the temperature dependence of the shape of electron spin resonance (ESR) spectra of the spin probe 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL). The spin probe was incorporated into the tuna meat from an aqueous solution of TEMPOL or by contact with a layer of TEMPOL crystals. The melting/freezing of freeze-concentrated solutes in frozen tuna meat was observed to take place over a range of temperatures from -25 to -10 degrees C. Lower temperatures gave ESR powder spectra due to the decreased mobility of the spin probe, and the temperature dependence of the mobility of the spin probe did not show abrupt changes at the glass transition temperatures of the systems. The mobility of nonglass forming solutes is concluded to be decoupled from the glass forming components. Similar behavior was also observed for TEMPOL in frozen, aqueous carbohydrate systems. The temperature dependence of the mobility of TEMPOL in the frozen systems was analyzed using the Arrhenius equation, and the logarithm of the Arrhenius preexponential factor tau(a) was found to be linearly correlated with the activation energy for all of the tuna and carbohydrate samples, indicating a common molecular mechanism for the observed mobility of TEMPOL in all of the systems. The linear correlation also suggests that the observed mobility of TEMPOL in the frozen aqueous systems is dominated by enthalpy-entropy compensation effects, where the mobility of TEMPOL is thermodynamically strongly coupled to the closest surrounding molecules.  相似文献   

Characterization of Cry34Ab1 and Cry35Ab1 insecticidal crystal proteins expressed in transgenic corn plants and Pseudomonas fluorescens     

Gao Y  Schafer BW  Collins RA  Herman RA  Xu X  Gilbert JR  Ni W  Langer VL  Tagliani LA 《Journal of agricultural and food chemistry》2004,52(26):8057-8065

Cry34Ab1 and Cry35Ab1 proteins, identified from Bacillus thuringiensis strain PS149B1, act together to control corn rootworms. Transgenic corn lines coexpressing the two proteins were developed to protect corn against rootworm damage. Large quantities of the two proteins were needed to conduct studies required for assessing the safety of this transgenic corn crop. Because it was technically infeasible to obtain sufficient quantities of high purity Cry34Ab1 and Cry35Ab1 proteins from the transgenic corn plants, the proteins were produced using a recombinant Pseudomonas fluorescens (Pf) production system. The two proteins from both the transgenic corn and the Pf were purified and characterized. The proteins from each host had the expected molecular mass and were immunoreactive to specific antibodies in enzyme-linked immunosorbent assay and Western blot analysis. Data from N-terminal sequencing, tryptic peptide mass fingerprinting, internal peptide sequencing, and biological activity provided direct evidence that the Cry34Ab1 and Cry35Ab1 proteins produced in Pf and transgenic corn were, respectively, comparable or equivalent molecules. In addition, neither protein had detectable glycosylation regardless of the host.  相似文献   

Spatial variability of enzyme activities in a 100-year old long-term field experiment     

Livia?B?hme  Frank?B?hmeEmail author  Uwe?Langer 《Biology and Fertility of Soils》2004,40(3):153-156

We attempted to clarify the importance of obtaining representative soil samples for microbiological purposes by comparing results from composite samples and individual cores taken at a depth of 30 cm from four different treatments at the Static Fertilisation Experiment in Bad Lauchstädt, Germany. As enzyme activities can be related to microbiological activities, we analysed alkaline phosphatase, -glucosidase and protease activities from the composite and individual samples. When comparing both kinds of samples, protease activity was found to be the most and -glucosidase activity the least variable parameter. Comparing just the individual cores, the greatest variation was found for alkaline phosphatase and the lowest variation for -glucosidase activity; however, the latter enzyme activity also showed significantly different values. Thus, care should be taken when sampling in the field for microbial purposes.

Frank BöhmeEmail: Phone: +49-345-5585420Fax: +49-345-5585449

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Sialic acid-containing milk proteins show differential immunomodulatory activities independent of sialic acid     

Mikkelsen TL  Bakman S  Sørensen ES  Barkholt V  Frøkiaer H 《Journal of agricultural and food chemistry》2005,53(20):7673-7680

The immunomodulatory activities of four sialic acid-containing milk proteins (kappa-casein, glycomacropeptide, lactoferrin, and proteose peptone-3 component) were determined, and the role of sialic acid was evaluated. Two in vitro models were used: murine splenocyte proliferation, where the effect on LPS-, Con A-, and PHA-stimulated proliferation was studied, and cytokine production in LPS-stimulated murine dendritic cells (DC). All four proteins inhibited LPS-induced splenocyte proliferation, though to different degrees, and independently of sialic acid. kappa-Casein strongly inhibited PHA-induced proliferation and had a weak inhibitory effect on Con A-induced proliferation, whereas lactoferrin stimulated Con A-induced proliferation. kappa-Casein, glycomacropeptide, and lactoferrin differentially affected cytokine production by DC: kappa-casein significantly inhibited production of TNF-alpha, IL-10, -12, -6, and -1beta, independent of sialic acid, whereas less-marked effects of glycomacropeptide and lactoferrin were seen. These findings thus point to important immunosuppressive effects of some milk proteins and indicate that they may function via different mechanisms.  相似文献   

Transient interface sharpening in miscible alloys     

Erdélyi Z  Sladecek M  Stadler LM  Zizak I  Langer GA  Kis-Varga M  Beke DL  Sepiol B 《Science (New York, N.Y.)》2004,306(5703):1913-1915

We observed that diffuse interfaces sharpen rather than broaden in completely miscible ideal binary systems. This is shown in situ during heat treatments at gradually increasing temperatures by scattering of synchrotron radiation in coherent Mo/V multilayers containing initially diffuse interfaces. This effect provides a useful tool for the improvement of interfaces and offers a way to fabricate better x-ray or neutron mirrors, microelectronic devices, or multilayers with giant magnetic resistance.  相似文献   

Angiogenesis inhibition and tumor regression caused by heparin or a heparin fragment in the presence of cortisone   总被引：28，自引：0，他引：28  

J Folkman  R Langer  R J Linhardt  C Haudenschild  S Taylor 《Science (New York, N.Y.)》1983,221(4612):719-725

Heparin or a heparin fragment administered with cortisone inhibited angiogenesis, caused regression of large tumor masses, and prevented metastases. Oral administration of heparin resulted in the release of non-anticoagulant heparin fragments in the serum which, in the presence of cortisone, had similar anti-angiogenic and antitumor effects. Of all the heparin fragments tested, the most potent inhibition of angiogenesis in the presence of cortisone was provided by a hexasaccharide with a molecular weight of about 1600.  相似文献   

Implementation of the semiclassical quantum Fourier transform in a scalable system     

Chiaverini J  Britton J  Leibfried D  Knill E  Barrett MD  Blakestad RB  Itano WM  Jost JD  Langer C  Ozeri R  Schaetz T  Wineland DJ 《Science (New York, N.Y.)》2005,308(5724):997-1000

We report the implementation of the semiclassical quantum Fourier transform in a system of three beryllium ion qubits (two-level quantum systems) confined in a segmented multizone trap. The quantum Fourier transform is the crucial final step in Shor's algorithm, and it acts on a register of qubits to determine the periodicity of the quantum state's amplitudes. Because only probability amplitudes are required for this task, a more efficient semiclassical version can be used, for which only single-qubit operations conditioned on measurement outcomes are required. We apply the transform to several input states of different periodicities; the results enable the location of peaks corresponding to the original periods. This demonstration incorporates the key elements of a scalable ion-trap architecture, suggesting the future capability of applying the quantum Fourier transform to a large number of qubits as required for a useful quantum factoring algorithm.  相似文献   

Relative validity of the pre-coded food diary used in the Danish National Survey of Diet and Physical Activity     

Knudsen VK  Gille MB  Nielsen TH  Christensen T  Fagt S  Biltoft-Jensen A 《Public health nutrition》2011,14(12):2110-2116

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