水热法ZnO晶体特征研究

ZnO具有优良的综合性能使其成为极有前途的下一代光电材料，水热法是一种重要的生长ZnO晶体的方法。本文对水热法生长的面积约150mm^2的ZnO晶体进行了报道，研究了晶体不同方向的生长速度、形貌特征和光学性能。X射线摇摆曲线表明晶体的质量较好。对于光学性质的分析表明晶体生长时加入H2O2能显著提高晶体的质量。494nm附近的发光带可能与氧空位有关。520nm的发光可能与Na或者Si所形成的杂质能级跃迁有关。

Low-temperature hydrothermal growth of oriented [0001] ZnO film

Well-aligned ZnO films have been successfully prepared by using low-temperature hydrothermal approach on (0001) sapphire substrates that were pre-coated with a ZnO nano-layer by dip-coating. The characterizations of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate that the ZnO films consist of hexagonal rods that grow along the c axis based on the sapphire substrates. It is found that the size of ZnO rods can be adjusted by an aqueous solution with some methenamine. (c) 2006 Elsevier B.V. All rights reserved.

Hydrothermal growth and characterization of ZnO crystals

ZnO crystals with dimensions of 30 x 38 x 8 turn 3 have been grown by the hydrothermal method using a mixed solution of KOH, LiOH and H2O2. The growing rates for +c(0001) and -c(000 (1) over bar) were 0.17 and 0.09 mm/day, respectively. The crystal color was very light green for +c sector and dark brown for -c sector. For the +c sector, the resistivity at room temperature was 80 0 cm, the carrier concentration was about 10(4)/cm(3), and the mobility was about 100 cm(2)/Vs. The full-width at half-maximum (FWHM) of double axis X-ray rocking curve for the polished Zn face cut from +c sector was 45 arcsec. The photoluminescence (PL) spectrum and the absorption spectrum of +c part of the crystals at room temperature were also reported and discussed in this paper. (c) 2008 Elsevier B.V. All rights reserved.

THE POSSIBLE INVOLVEMENT OF TISSUE-TYPE PLASMINOGEN-ACTIVATOR IN LUTEOLYSIS OF RHESUS-MONKEY

Changes of plasminogen activators (PA) during different stages of development of the corpus luteum, and their possible physiological role in luteolysis were studied in rhesus monkeys. It was demonstrated for the first time that monkey corpus luteal cells not only produce PA, but that the function of the corpus luteum is also closely related to the activity of this enzyme system. Generally, the life span for a corpus luteum in monkey is approximately 14-16 days, its demise beginning thereafter. In the present study, we found that urokinase in the corpus luteum is higher on day 5 and day 10 after human chorionic gonadotrophin injection, while the tissue type (t) PA is mainly produced on day 13 when luteolysis may take place. Progesterone production remained high on day 5 and day 10 and decreased dramatically from day 13, indicating the important role of tPA but not urokinase (u) PA in suppressing luteal function. When purified tPA (but not uPA) monoclonal antibody was added to luteal cell culture to neutralize endogenously produced tPA activity, progesterone production in the cells was increased significantly. Interestingly, prolactin alone was capable of increasing PA production by luteal cells; prolactin together with luteinizing hormone, however, had a synergistic luteotrophic effect.

Stress enables synaptic depression in CA1 synapses by acute and chronic morphine: Possible mechanisms for corticosterone on opiate addiction

The hippocampus, being sensitive to stress and glucocorticoids, plays significant roles in certain types of learning and memory. Therefore, the hippocampus is probably involved in the increasing drug use, drug seeking, and relapse caused by stress. We have studied the effect of stress with morphine on synaptic plasticity in the CA1 region of the hippocampus in vivo and on a delayed-escape paradigm of the Morris water maze. Our results reveal that acute stress enables long-term depression (LTD) induction by low-frequency stimulation (LFS) but acute morphine causes synaptic potentiation. Remarkably, exposure to an acute stressor reverses the effect of morphine from synaptic potentiation ( similar to 20%) to synaptic depression ( similar to 40%), precluding further LTD induction by LFS. The synaptic depression caused by stress with morphine is blocked either by the glucocorticoid receptor antagonist RU38486 or by the NMDA-receptor antagonist D-APV. Chronic morphine attenuates the ability of acute morphine to cause synaptic potentiation, and stress to enable LTD induction, but not the ability of stress in tandem with morphine to cause synaptic depression. Furthermore, corticosterone with morphine during the initial phase of drug use promotes later delayed-escape behavior, as indicated by the morphine-reinforced longer latencies to escape, leading to persistent morphine-seeking after withdrawal. These results suggest that hippocampal synaptic plasticity may play a significant role in the effects of stress or glucocorticoids on opiate addiction.

A possible mode of the specific recognition of nucleic acids by proteins

Seven sets of protein target sites, which occur in several gene promoters, have been analyzed. The results suggest that there is a possible mode of specific recognition of double-helical nucleic acids by proteins, This recognition mode is related to a spe