Complexation and toxicity of copper and the free metal bioassay technique

The concentrations of free and total copper toxic to Daphnia and guppies were determined in inorganic media with and without addition of various concentrations of β-alanine, glycine, glutamic acid or Tris. Free copper concentrations were determined using a cupric ion electrode. Stability constants calculated for each of the detected complexes compared favourably with previously published values, with the possible exception of the Cu(OH)₂ complex. Free copper concentrations in solutions equally toxic to Daphnia were observed to vary greatly, primarily because of the toxicity of copper amino acid complexes to this organism. The copper/amino acid complexes were, nevertheless, less toxic than the free copper ions. The copper/β-alanine complex was observed to be less toxic to guppies than to Daphnia, indicating a difference in sensitivity to different copper complexes in different organisms. Copper/Tris complexes were found to be only slightly toxic to both Daphnia and guppies. A bioassay technique for determining free copper concentrations by comparing copper toxicity before and after addition of Tris was tested and verified. Although free metal concentrations can be determined from properly conducted bioassays, the variation in free metal concentration in equally toxic solutions demonstrates that free metal concentrations cannot be calculated by simply comparing metal toxicity in a test solution with toxicity of the same metal in a standard solution with known free metal concentration, unless it is known that no complexes are present in the test solution which can form toxic complexes with the metal.     

Luteinizing hormone response to gonadotrophin-releasing hormone in normal women undergoing ovulation induction with urinary or recombinant follicle stimulating hormone

Oestradiol enhances pituitary sensitivity to gonadotrophin-releasing hormone (GnRH) in normal women, while in women undergoing ovulation induction the putative factor gonadotrophin surge attenuating factor (GnSAF) attenuates the response of luteinizing hormone (LH) to GnRH. To study the relationships between oestradiol and GnSAF during ovulation induction, 15 normally ovulating women were investigated in an untreated spontaneous cycle (control, first cycle), in a cycle treated with daily i.m. injections of 225 IU urinary follicle-stimulating hormone (FSH) (Metrodin HP, uFSH cycle) and in a cycle treated with daily s.c. injections of 225 IU recombinant FSH (Gonal-F, rFSH cycle). Treatment with FSH started on cycle day 2. The women during the second and third cycle were allocated to the two treatments in an alternate way. One woman who became pregnant during the first treatment cycle (rFSH) was excluded from the study. In all cycles, an i.v. injection of 10 microg GnRH was given to the women (n = 14) daily from days 2-7 as well as from the day on which the leading follicle was 14 mm in diameter (day V) until mid-cycle (n = 7). The response of LH to GnRH at 30 min (deltaLH), representing pituitary sensitivity, was calculated. In the spontaneous (control) cycles, deltaLH values increased significantly only during the late follicular phase, i.e. from day V to mid-cycle, at which time they were correlated significantly with serum oestradiol values (r = 0.554, P < 0.01). Initially during the early follicular phase in the uFSH and the rFSH cycles, deltaLH values showed a significant decline which was not related to oestradiol (increased GnSAF bioactivity). Then, deltaLH values increased significantly on cycle day 7 and further on day v with no change thereafter up to mid-cycle. On these two days, deltaLH values were correlated significantly with serum oestradiol values (r = 0.587 and r = 0.652 respectively, P < 0.05). During the pre-ovulatory period, deltaLH values in the FSH cycles were significantly lower than in the spontaneous cycles. Significantly higher serum FSH values were achieved during treatment with uFSH than rFSH. However, serum values of oestradiol, immunoreactive inhibin, and deltaLH as well as the number of follicles > or = 12 mm in diameter did not differ significantly between the two FSH preparations. These results suggest that in women undergoing ovulation induction with FSH, oestradiol enhances pituitary sensitivity to GnRH, while GnSAF exerts antagonistic effects. The rFSH used in this study (Gonal-F) was at least as effective as the uFSH preparation (Metrodin-HP) in inducing multiple follicular maturation in normally cycling women.     

PHEM T 材料MBE 生长及其应用

我们对PHEMT材料中应变沟道InGaAs层生长条件进行了优化,并采用了LT-GaAs中缺陷扩散的阻挡层.功率PHEMT器件结果为在栅长Lg=1.0μ时,跨导g\-m≥400 ms/mm,BV\-\{DS\}>1 5V,BV\-\{GS\}>10V表明该材料有较好的性能.作为材料的缓冲层,结果表明器件性能优良 ,是国内最好结果.