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The self-organization of pyramidal PbSe islands that spontaneously form during strained-layer epitaxial growth of PbSe/Pb1-xEuxTe (x = 0.05 to 0.1) superlattices results in the formation of three-dimensional quantum-dot crystals. In these crystals, the dots are arranged in a trigonal lattice with a face-centered cubic (fcc)-like A-B-C-A-B-C vertical stacking sequence. The lattice constant of the dot crystal can be tuned continuously by changing the superlattice period. As shown by theoretical calculations, the elastic anisotropy in these artificial dot crystals acts in a manner similar to that of the directed chemical bonds of crystalline solids. The narrow size distribution and excellent control of the dot arrangement may be advantageous for optoelectronic device applications. 相似文献
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Use of a rapid method of cryopreservation of bovine embryos for non-surgical transfer in transplantation practice 总被引：1，自引：0，他引：1
L Holy A Jirícek M Zák M Capeková V Dvoráková M Lopatárová 《Veterinární medicína》1985,30(10):577-584
The embryos were frozen and thawed in Cassou minipaillette by a rapid method. Embryos with cryoprotective agent (glycerol, 1.5 M) were placed directly into the freezing medium at the temperature of -6 to -7 degrees C, frozen after seedling at the temperature decrease by 0.3 to 0.5 degrees C per minute to the temperature of -32 degrees C and then transferred directly into liquid nitrogen. They were thawed in a bath warm 20 to 37 degrees C. After thawed the cryoprotective agent was evacuated in 1.1 M sucrose. The best-quality embryos were selected for freezing. Out of these 366 thawed so far, with average survival of 74.31%. The total of the 268 thawed embryos were transferred ipsilaterally, by a non-surgical method, to 190 synchronised heifers, out of which 105 (55.26%) got in calf. Rapid freezing method based on 1.5 M of glycerol and thawing at the presence of 1.1 M sucrose proved effective and suitable for practice, as not only sufficient reviviscence of embryos and their survival in womb are guaranteed, but also a substantial shortening of the freezing as well as thawing process. 相似文献
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L Holy 《Veterinární medicína》1984,29(9):513-519
Trials were performed to examine the effectiveness of 250 micrograms (1 ml) of cloprostenol (Oestrophan Spofa) implantation under the mucous membrane of the vaginal vestibule of 128 cows with a clinically pronounced corpus luteum on ovaries. Within 72 hours from administration, oestrus was observed in 112 animals (85.5%). Out of the 97 cows inseminated, 63 cows (64.94%) got in calf. The effectiveness of the luteolytic action was examined on the basis of progesterone check in milk in 56 treated cows. The submucous implantation of cloprostenol rapidly degraded the function of the corpus luteum since from the original level of 14.78 ng/ml progesterone decreased to 0.87 ng/ml within 72 hours. However, luteolysis did not affect all the corpora lutea. Hence the submucous administration of cloprostenol was found to be effective, and at the same time, highly economical, owing to a substantial reduction in the costs of reproduction control as well as the costs of production. 相似文献
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The vomeronasal organ (VNO) of mammals plays an essential role in the detection of pheromones. We obtained simultaneous recordings of action potentials from large subsets of VNO neurons. These cells responded to components of urine by increasing their firing rate. This chemosensory activation required phospholipase C function. Unlike most other sensory neurons, VNO neurons did not adapt under prolonged stimulus exposure. The full time course of the VNO spiking response is captured by a simple quantitative model of ligand binding. Many individual VNO neurons were strongly selective for either male or female mouse urine, with the effective concentrations differing as much as a thousandfold. These results establish a framework for understanding sensory coding in the vomeronasal system. 相似文献
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SK Shaheenur Islam Holy Akwar Md. Mehedi Hossain Md. Abu Sufian Md. Zakiul Hasan Shovon Chakma Tongkorn Meeyam Warangkhana Chaisowwong Veerasak Punyapornwithaya Nitish C. Debnath Eric Brum Duangporn Pichpol 《Zoonoses and public health》2020,67(6):658-672
Analysis of environmental samples obtained from the Live Poultry Markets (LPMs) of Dhaka City, Bangladesh, has revealed that the highest degree of prevalence of highly pathogenic avian influenza A (HPAI, H5N1), besides other subtypes of the LPAI virus, poses the plausible risk of transmission of these viruses between human and poultry species. The present study was conducted using the OIE risk analysis framework to assess the risk level of each pathway successively. The estimated risk parameters were integrated towards to obtain the overall risk level for each specific HPAI transmission pathway using the matrix adapted by Cristobel Zepeda accompanying other expert consultations. The relevant data obtained from published and unpublished sources, together with survey data of field observations, were used to formulate and confirm the risk pathways and their associated risks. The results revealed that the risk of the release of the HPAI virus was medium when exposure was high. Additionally, the consequence would be considered very high with a medium degree of uncertainty for all parameters. Ultimately, the overall risk for transmission was estimated as medium with a medium degree of uncertainty. The findings of this study reveal that there is a significant threat that HPAI virus transmission could occur among poultry and humans and effectively sustain within the environment of the LPMs. Our findings are primarily focused on public health considerations, the hygienic slaughter of poultry and the relevant cleaning and sanitation practices conducted in the LPMs to support evidence‐based decision‐making processes. The findings of the study have the potential to be used to formulate effective risk reduction measures and can be further adapted in low‐resource settings without major infrastructural changes required of the LPMs. All of which would reduce the risk of HPAI virus release and further lessen the degree of exposure and transmission in established LPMs. 相似文献
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L Holy 《Veterinární medicína》1987,32(11):643-653
The results are analyzed of superovulation stimulation in the donors and the non-surgical embryo transfer in cattle. After superovulation induced by means of PMSG (Bioveta, Ivanovice in Haná) 6.2 and 6.3 ova and embryos were obtained, of which 66 to 70%, i. e. 4.2 and 4.3 embryos, respectively, were applicable in transfer. When the combination of PMSG with antigonadotropin (Antisergon, Bioveta, Ivanovice in Haná) was used, the embryos had somewhat better quality and their applicability was increased. After adjustment of the time of Antisergon administration the number of recovered ova and embryos was increased to 10.3 with 82.3% applicability (8.5 embryos per superovulation/donor). After super-ovulation stimulated with Folicotropin (Léciva, Praha) the yield of ova was 12.7, and 10.1 of the embryos (79.8%) were applicable. After the use of FSH-P (Burna-Biotec) 13.8 and 10.9 embryos were obtained per one superovulation. Non-surgical embryo transfer was performed in 1321 recipients over the last two years and a half. In 1984 the conception rate was 52.4%, in 1985 the average survival increased to 58.33% and in the first half of 1986 it reached 65.5%. 相似文献
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Early and late blastocysts (D7) of excellent quality were bisected by the transzonal method. The developing semiembryos without zonal protection were transferred to synchronised recipients--heifers. After bilateral transfer of the identical pair (always one semiembryo into one uterine cornu) 79.7% of the heifers were impregnated. The total gravidity was 58.8%. After ipsilateral transfer (the halves transferred individually) gravidity was confirmed in 48.2% of the cases. The survival efficiency of the halves with respect to the number of bisected embryos was 117.6% in bilateral transfer and it decreased to 93.3% after ipsilateral transfer. Identical pregnancies of twins were recorded in 36.8% of the bilateral transfers and in ipsilateral transfers only 20% of the identical pairs survived. We demonstrated the high recuperative and regenerative ability of the bovine 7 day old blastocyst by means of transzonal bisection. This was dependent on the selection of the appropriate embryo, careful manipulation aseptic technique, biologically compatible cultivation medium and rapid transfer. It is possible to attain satisfactory semiembryo survival levels in transplantation work and by means of this a significant increase of the superovulation effect. 相似文献
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The descent and localization of eggs and embryos in individual segments of the reproductive tract of superovulated cows were studied in this work. For the induction of superovulation, serum gonadotropin (PMSG, Ivanovice in Haná) at a dose of 2,500-3,500 I.U. was used, in combination with 0.5 mg of Cloprostenol (Oestrophan, Spofa), administered 48 hours after gonadotropin treatment. The start of superovulation fell on days 9 to 12 of the sexual cycle and was conditioned by the presence of the corpus luteum (CL). After the onset of the heat, 2-3 inseminations were carried out using fresh semen. Donor cows were slaughtered 3, 4, 5, 6, and 7 days after the second insemination and isolated reproductive organs (Fig. 1) were divided into five segments (two on oviducts and three on uterine horns) by the applied ligature. In laboratory conditions superovulation response was determined accurately, the volume of ovaries was assessed according to water displacement and the segments of oviducts and uterus were rinsed with TCM 199 or PBS supplemented with FCS. 3, 4, 5, 6, and 7 days after insemination (Tab. I). 18.1 (+/- 3.55), 12.4 (+/- 0.91), 19.2 (+/- 2.86), 20 and 23 (+/- 2.44) CL on average were recorded, which corresponded to the ovulation of 64, 50, 56, 71 and 72 percent of stimulated follicles (Fig. 2). Within 3 to 7 days after insemination nearly triple enlargement of ovaries was also observed (Tab. I, Fig. 3). During the lavage of individual segments of the tubular reproductive tract, 38 per cent of eggs and embryos were detected in the uterus as early as 3 days after insemination (Tab. II). Unfertilized eggs and degenerated embryos were found in the 2nd and 3rd uterine segment, embryos at the stage of 8-16 blastomeres were localized in the 1st and 2nd segment of the uterus. Four days after insemination (Tab. III), about 64 per cent of eggs and embryos at the stage up to 16 blastomeres were found in the uterus, but embryos up to 32 blastomeres were still flushed out of the oviduct. On day 5 after insemination, 92 per cent of eggs and embryos were released into the uterus, being localized mostly in the cranial and medial part of the uterus (Tab. IV). 7.5 per cent of recovered eggs and embryos at the stage of early or compacted morulae were still detected in the oviducts.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献