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1.
de Medeiros Bastos G Brenner RH Willke FW Neves JP de Oliveira JF Bragança JF Machado SA Porciúncula PM Gonçalves PB 《Theriogenology》2004,62(5):847-853
The objective was to develop a program for inducing estrus (followed by insemination) of suckled beef cows under nutritional stress (poor body condition). A total of 123 cows, from 60 to 75 days postpartum, were classified according to their body condition score (BCS; range from 1 to 5, in increments of 0.5) and allocated into two groups. On Day 0 (without regard to stage of the estrous cycle), cows (n = 59) in the hormone induction (HI) treatment group were given an intravaginal device (IVD) containing 250 mg of medroxiprogesterone acetate (MAP) and an i.m. injection of 2.5 mg estradiol benzoate (EB). On Day 6, these cows were given 500 IU eCG i.m. and calves were weaned for 96 h. The IVD were removed on Day 7. Cows detected in estrus by 45 h after IVD removal were inseminated 12 h after standing estrus; cows not in estrus by 45 h after IVD removal received an i.m. injection of 100 microg gonadorelin (GnRH) and were inseminated 16-18 h later. In the control group (C), cows (n = 64) only had their calves weaned at Day 6 (for 96 h), with estrus detection and AI from Days 6 to 11. Overall, the BCS ranged from 2.0 to 3.0. In the treatment group, estrus and pregnancy rates in cows with BCS 2.0 (20 and 30%, respectively) was lower (P < 0.05) than those with BCS 3.0 (50 and 66.6%, respectively), but did not differ (P > 0.05) from BCS 2.5 (23.3 and 47.6%). In C group, only 2 of 66 cows were detected in estrus and bred (neither was pregnant). In conclusion, the program for induction of ovulation using MAP, EB, eCG and GnRH increased the pregnancy rate in beef cows in poor body condition, enabling AI to be done in a 63-h interval. 相似文献
2.
Ali C Akyildiz Lambert Speelman Harald van Brummelen Miguel A Gutiérrez Renu Virmani Aad van der Lugt Anton FW van der Steen Jolanda J Wentzel Frank JH Gijsen 《Biomedical engineering online》2011,10(1):25
Background
Rupture of the cap of a vulnerable plaque present in a coronary vessel may cause myocardial infarction and death. Cap rupture occurs when the peak cap stress exceeds the cap strength. The mechanical stress within a cap depends on the plaque morphology and the material characteristics of the plaque components. A parametric study was conducted to assess the effect of intima stiffness and plaque morphology on peak cap stress. 相似文献3.
Microbial production of itaconic acid: developing a stable platform for high product concentrations 总被引:1,自引:0,他引:1
Anja Kuenz Yvonne Gallenmüller Thomas Willke Klaus-Dieter Vorlop 《Applied microbiology and biotechnology》2012,96(5):1209-1216
Biotechnologically produced itaconic acid (IA) is a promising organic acid with a wide range of applications and the potential to open up new application fields in the area of polymer chemistry, pharmacy, and agriculture. In this study, a systematic process optimization was performed with an own isolated strain of Aspergillus terreus and transferred from a 250-mL to a 15-L scale. An IA concentration of 86.2?g/L was achieved within 7?days with an overall productivity of 0.51?g/(L?h), a maximum productivity of 1.2?g/(L?h), and a yield of 86?mol%. A cultivation of other well-known A. terreus strains with the developed process showed no significant differences. Based on this, a process is developed providing a high final IA concentration independent of the used strain combined with high reproducibility. 相似文献
4.
High-level production of 1,3-propanediol from crude glycerol by <Emphasis Type="Italic">Clostridium butyricum</Emphasis> AKR102a 总被引:1,自引:0,他引:1
Wilkens E Ringel AK Hortig D Willke T Vorlop KD 《Applied microbiology and biotechnology》2012,93(3):1057-1063
The aim of this study was to optimize a biotechnological process for the production of 1,3-propanediol (1,3-PD) based on low-quality
crude glycerol derived from biodiesel production. Clostridium butyricum AKR102a was used in fed-batch fermentations in 1-L and 200-L scale. The newly discovered strain is characterized by rapid
growth, high product tolerance, and the ability to use crude glycerol at the lowest purity directly gained from a biodiesel
plant side stream. Using pure glycerol, the strain AKR102 reached 93.7 g/L 1,3-PD with an overall productivity of 3.3 g/(L*h).
With crude glycerol under the same conditions, 76.2 g/L 1,3-PD was produced with a productivity of 2.3 g/(L*h). These are
among the best results published so far for natural producers. The scale up to 200 L was possible. Due to the simpler process
design, only 61.5 g/L 1,3-PD could be reached with a productivity of 2.1 g/(L*h). 相似文献
5.
3-hydroxypropionaldehyde (3HPA) is a promising versatile substance derived from the renewable feedstock glycerol. It is a product of glycerol metabolism in Lactobacillus reuteri. Because of toxic effects, the biotechnological production is poor. In this work the biocatalyst lifetime and product formation could be drastically increased. In the established two-step process already applied, cells are grown in the first step under anaerobic conditions, and in the second step the immobilised or suspended biocatalyst is used for 3HPA-production under strict anaerobic conditions. In the first step it was possible to reach a biomass concentration of 5.5g CDW/L (OD(600)≈23.4). In the second step, normally, 3HPA accumulates to a toxic concentration and the reaction stops in less than 60min because of the interaction of 3HPA with cell components. To prevent this, the toxic product is bound to the newly found scavenger carbohydrazide to form the hydrazone. For the first time it was possible to recycle the immobilised biocatalyst for at least ten cycles (overall life time>33hours) in a repeated batch biotransformation with an overall production of 67g 3HPA. The optimal pH-value was between 6.8 and 7.2 at an optimal temperature of 40-45°C. In a single batch biotransformation with suspended resting cells it was possible to produce 150g/L 3HPA as carbohydrazone at an overall productivity of 10.7gL(-1)hours(-1). In a single fed-batch biotransformation at 45°C 138g/L glycerol was converted into 108g/L 3HPA with an overall productivity of 21.6gL(-1)hours(-1). This is the highest 3HPA concentration and productivities reported so far for the microbial production of 3HPA from glycerol. 相似文献
6.
Itaconic acid (IA) is an unsaturated dicarbonic organic acid. It can easily be incorporated into polymers and may serve as a substitute for petrochemical-based acrylic or methacrylic acid. It is used at 1-5% as a co-monomer in resins and also in the manufacture of synthetic fibres, in coatings, adhesives, thickeners and binders. The favoured production process is fermentation of carbohydrates by fungi, with a current market volume of about 15,000 t/a. Due to the high price of about US$ 4/kg, the use of IA is restricted. At present, the production rates do not exceed 1 g l(-1) h(-1), accompanied by product concentrations of about 80 g l(-1). New biotechnology approaches, such as immobilisation techniques, screening programmes and genetic engineering, could lead to higher productivity. Also, the use of alternative substrates may reduce costs and thus open the market for new and increased applications. 相似文献
7.
Frank JH Gijsen Francesco Migliavacca Silvia Schievano Laura Socci Lorenza Petrini Attila Thury Jolanda J Wentzel Anton FW van der Steen Patrick WS Serruys Gabriele Dubini 《Biomedical engineering online》2008,7(1):23
Background
The process of restenosis after a stenting procedure is related to local biomechanical environment. Arterial wall stresses caused by the interaction of the stent with the vascular wall and possibly stress induced stent strut fracture are two important parameters. The knowledge of these parameters after stent deployment in a patient derived 3D reconstruction of a diseased coronary artery might give insights in the understanding of the process of restenosis. 相似文献8.
Forbes SH; Hogg JT; Buchanan FC; Crawford AM; Allendorf FW 《Molecular biology and evolution》1995,12(6):1106-1113
We compared genotypes at eight (AC)n microsatellite loci in domestic sheep
(Ovis aries) and wild Rocky Mountain bighorn sheep (O. canadensis). The
domestic sheep had greater genetic variation, higher allele-size variances,
and larger allele sizes than the wild sheep. Accumulating evidence from
higher taxonomic comparisons shows that these parameters are biased if
microsatellite loci are selected in one taxon and used in another. Our
results demonstrate similar biases between congeneric species. We compared
standard measures of genetic variation, differentiation, and distance
within and between species (H, D, FST) to newer measures based on
allele-size variance (SW, SB, RST). The size-based distances better
detected species-level divergence, but standard measures better
distinguished allopatric populations. Empirical calibration of these
measures at the subspecies level is needed to establish their useful
ranges.
相似文献
9.
Olfactory sensitivity in tsetse flies: a daily rhythm 总被引:3,自引:0,他引:3
The diurnal tsetse Glossina morsitans morsitans bites especially in early
morning and late afternoon; around midday feeding is at a low. In
laboratory apparatus that measures the amount of locomotion under constant
conditions over the photophase, the flies display a similar patterning of
activity levels. The profile of daily rhythms for G. morsitans reported in
the literature includes a number of motor and sensory motor systems that
fluctuate cophasically. Lacking is a study on the patterning of the senses'
response levels. In this paper we present the first instance of a daily
modulation in the sense of smell. We stimulated the antennae with
concentration series of host-derived odours and measured the spiking rate
of cells at different times during the photophase. The
concentration-response curves suggest that the sensitivity of antennal
olfactory cells flows in parallel with the other daily rhythms. This was
also reflected in electroantennograms (EAGs). The electroantennography was
extended to G. fuscipes fuscipes, whose level of spontaneous locomotor
activity--instead of following a U- shaped pattern--rises gradually over
the photophase. Again, the EAGs appeared to parallel the species' locomotor
activity. What we believe happens is that the organism tones down the
sensitivity of its odour receptors during periods of anticipated inactivity
for reasons of economy.
相似文献
10.