Authors:Z. En, J. Brenizer, B. Hosticka, J. Gao, and D. Becker
A method utilizing plastic track detectors was developed to determine the nitrogen distribution and concentration in the presence
of boron in metals. Experiments were performed at the UVAR (cadmium ratio ≈25) and the NIST Reactor (cadmium ratio ≈3000).
The minimum detectable concentration of nitrogen at a given concentration of boron has been estimated using the detector’s
response to10B(n,α)7 Li reaction products in terms of track size distribution. The capability of the technique to detect nitrogen in the presence
of boron has been demonstrated using 316L stainless steel with a nitrogen concentration of ≈560 ppm and a boron concentration
of ≈0.86 ppm.
Authors:Z. En, J. Brenizer, B. Hosticka, and D. Becker
The paper is devoted to determination of boron and nitrogen in metallic materials by nuclear track techniques for the case of high background in radiograms. The method is based on the detection of the 10B(n,)7Li and 14N(n,p)14C reaction products with plastic track detectors exposed to a neutron flux in a close contact with the samples analyzed. When determining boron, high background can arise due to fast neutron interactions with hydrogen existing in the detector material and with matrix elements of the sample. In the case of nitrogen determination, high background is usually associated with a presence of boron in metals and alloys, alpha tracks of which strongly interfere with proton tracks from the 14N(n,p)14C reaction. The feasibility for measurement of micro-concentrations of boron as well as nitrogen determination in the presence of boron has been studied.
Authors:J. Magoshi, M. Becker, Z. Han, and S. Nakamura
Thermal properties of seed proteins, prolamines from rice, wheat and soybean were studied by differential scanning calorimetry
(DSC), thermogravimetry (TG), thermal expansion, X-ray diffraction and infrared spectroscopy. Prolamine films cast from aqueous
ethanol are amorphous in the random-coil conformation. The glass transition of prolamine is observed at 160, 172 and 150C
for rice, wheat and soybean, respectively. The amorphous prolamine films crystallize at 196, 205 and 199C for rice, wheat
and soybean, respectively. The thermal degradation of prolamine films occurs from 228, 250 and 270C for rice, wheat and soybean,
Authors:R. Lindstrom, D. Becker, J. Langland, and R. Greenberg
Apparatus is being developed for short irradiation and rapid counting at the NIST Reactor, optimized for accurate neutron activation analysis via activation products ranging in half-life from about 500 ms to 500 s. This facility is designed to irradiate a sample either in a well-thermalized neutron flux at 3·1013 n·cm–2·s–1, or in a higher flux with a larger fast and epithermal component. The design transfer time for a 1-ml rabbit is 500 ms, measured to 10 ms precision. Timing information for both irradiation and counting will be transferred automatically to the activation analysis workstation computer. The -ray spectrometer system is selected and tuned for accurate measurement at high and varying counting rates, using loss-free counting (LFC) technology. A detailed calibration and characterization of this system has been performed. Accurate measurement requires that attention be paid to the systematic and random errors to which LFC is subject, but this requirement is minor compared to the advantages of undistorted spectral shape, the ability to solve the decay equations exactly, and the wider useful range of counting rates in the spectrometer system.
Authors:P. V. Drion, A. Zarrouk, J. Sulon, O. Szenci, J. F. Beckers, Zs. Perényi, B. Remy, and J. M. Garbayo
The Pregnancy Associated Glycoproteins (PAGs) presented in this paper are largely expressed in the ruminant placenta. These proteins are classified as probably inactive members of the aspartic proteinase family. Pepsinogen, renin, cathepsin E & D and chymosine are typical members of this family, characterised by the presence of aspartic acids boarding the recognition sites. Secreted in the peripheral blood of the pregnant female from early pregnancy, these proteins can be used in serological tests for establishing different diagnoses. In the veterinary practice, these diagnoses are useful for both pregnancy confirmation and follow-up of trophoblastic function. The first aspect can help breeders in the management of reproduction, while the second one more specifically concerns clinicians and researchers wishing to establish a differential diagnosis of pathologic conditions affecting pregnancy.
Authors:P. V. Drion, O. Szenci, F. Ectors, D. Wirth, Zs. Perényi, P. Muller, and J. F. Beckers
The technology of reproduction progressed considerably during the last decade, leading to a certain availability of in vitro methods for fertilisation, oocyte maturation and embryo culture. The most spectacular manipulations are cloning and transgenesis. This review focuses on the early appearance of germinal cell precursors and the long-standing fate of gametes in mammals. The evident complexity and long-term programming of events in gametes and early embryos explain part of the difficulties encountered during the development of in vitro and in vivo methods such as multiple ovulation and embryo transfer (MOET), oestrus synchronisation, ovulation induction, superovulation, in vitro maturation and fertilisation, cryopreservation, transgenesis, nuclear transfer and cloning) and the occurrence of unexpected alterations of development, e.g. embryonic or fetal mortality, large-weight newborn syndrome and other dysregulations in imprinting or DNA transmission.
Authors:C. -H. Horte, Chr Becker, G. Kranz, E. Schiller, and J. Wiegmann
Through a combination of X-ray diffraction and thermal analysis (simultaneous TG-DTG-DTA and quasi-isothermal TG), it was shown that the molar ratio intercalation agent/kaolinite in all intercalation compounds is approximately 1. In a saturated atmosphere of the corresponding intercalation agent, the intercalation compounds are stable up to more than 150 °C.
Authors:F. Becker, J. Kurth, F. Schneider, G. Nürnberg, H. Heinrich, and W. Kanitz
The aim of this study was to prove if oxidation-reduction levels in the follicular fluid were new functional indices of follicular health and whether there was a high level of accordance with endocrinological parameters and with the growth stage as detected by ultrasound monitoring of individual follicles during the oestrous cycle in mares. Follicles were classified as growing and regressing follicles using ultrasonography. Altogether 48 follicles with a diameter from 20 to 56 mm were aspirated by transvaginal ultrasound guided follicular aspiration. Follicular concentration of oestradiol and progesterone in relation to the diameter of growing follicles showed correlations of r = 0.64 and r = 0.57, respectively. The redox potential derived index D2 varied from -448 to +431 in the collected fluids of the follicles. The accordance of the judgement of all follicles using both complexes of methods - endocrinological and ultrasonographic parameters vs. analysis of oxidation and reduction levels - reached 72.5%. This finding has shown that parameters of redox reactions do not correlate closely with the stage of follicular growth or regression as determined by in vivoscanning of ovaries or by assessment of follicular steroid concentrations. However, the measurement of redox potentials offers an opportunity to examine the whole process of metabolism in follicular cells and to forecast impairments of cellular performances. Changes of redox parameters in growing follicles enable an earlier prediction of their further development. The data demonstrate that growing and regressing follicles do not represent nonatretic, early atretic and atretic follicles, respectively.
Authors:René Becker, Sebastiaan (Bas) A.M.W. van den Broek, Pieter J. Nieuwland, Kaspar Koch, and Floris P.J.T. Rutjes
To expand the knowledge base for fundamental organic reactions in continuous flow, the α-bromination of acetophenone was successfully transformed from a known batch procedure to a continuous flow process in 99 % yield through D-optimal optimisation and subsequent scale-up of the validated optimum. Using a preparative scale system, a space–time yield of 0.26 kg/m3/s (comparable literature batch reaction 0.24 kg/m3/s) was achieved under conditions suitable for laboratory and small-scale industrial application where high yield or purity is required, e.g., when expensive substrates are used.
Authors:T. Tanaka, J. Magoshi, Y. Magoshi, S. ichi Inoue, M. Kobayashi, H. Tsuda, M. Becker, and Sh. Nakamura
The thermal properties of liquid silk from domestic and wild silkworms are investigated. Liquid silks obtained from the silk
gland of the domesticated silkworm, Bombyx mori and four wild silkworms, Samia cynthia ricini, Dictyoploca japonica, Antheraea
pernyi and Antheraea yamamai were used. The DSC curves for the liquid silk from the domestic silkworm have weak endothermic
peaks corresponding to the breaking of hydrogen bonds in the β-form or to the untangling of physical network. The DSC curves
for the wild silkworm silks, however, show clear exothermic peaks corresponding to a phase transition from the α-helix conformation
to the β-form. Liquid silk from all the different silkworms undergoes a characteristic irreversible phase transition.