The Effect of the CO32- to Ca2+ Ion activity ratio on calcite precipitation kinetics and Sr2+ partitioning

Background  

A proposed strategy for immobilizing trace metals in the subsurface is to stimulate calcium carbonate precipitation and incorporate contaminants by co-precipitation. Such an approach will require injecting chemical amendments into the subsurface to generate supersaturated conditions that promote mineral precipitation. However, the formation of reactant mixing zones will create gradients in both the saturation state and ion activity ratios (i.e., ). To better understand the effect of ion activity ratios on CaCO₃ precipitation kinetics and Sr²⁺ co-precipitation, experiments were conducted under constant composition conditions where the supersaturation state (Ω) for calcite was held constant at 9.4, but the ion activity ratio was varied between 0.0032 and 4.15.     

Effects of BPA and DES on longchin goby (Chasmichthys dolichognathus) in vitro during the oocyte maturation

This study was performed in order to assess whether bisphenol (BPA) and diethylstilbestrol (DES) had agonistic or antagonistic effects on oocyte maturation using marine fish. We tested the effects of these chemicals on in vitro maturation, germinal vesicle breakdown (GVBD), assay using oocytes from the longchin goby, Chasmichthys dolichognathus. During the maturation process, low concentrations of BPA and DES triggered GVBD depending on the stage of oocyte development; BPA at 0.044 nM and DES at 0.037, 0.37, and 3.73 nM induced GVBD in 0.82-0.88 mm diameter oocytes (germinal vesicle located near the center of oocytes). In 0.76-0.80 mm diameter oocytes (fully vitellogenic oocytes), BPA induced GVBD at relatively higher concentrations (4.38, 43.8, and 438 nM). In 0.86-0.90 mm diameter oocytes, BPA and DES had no observable effect on GVBD at the concentrations tested. Oocytes with diameters between 0.82 and 0.88 mm appeared to be more sensitive to these chemicals. Moreover, our results showed that BPA and DES did not inhibit GVBD.     

有关地震区划的综合模型

引言本世纪中叶以来,随着科技、经济和社会的发展,城市已产生了引人注目的变化。人口和基础设施的增加,以及居民社会和经济条件的显著变化成为当今城市的典型特征。最近数10年地震造成的数以千计的严重伤亡事故和数以百万美元计的经     

Statistical Properties of SGR 1806-20 Bursts

We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary Explorer. We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.76, and 1.67, respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with a peak at 103 s. There is no correlation between the burst intensity and either the waiting times until the next burst or the time elapsed since the previous burst. In all these statistical properties, SGR 1806-20 bursts resemble a self-organized critical system, similar to earthquakes and solar flares. Our results thus support the hypothesis that the energy source for soft gamma repeater bursts is crustquakes due to the evolving, strong magnetic field of the neutron star, rather than any accretion or nuclear power.     

英国西北陆缘的漂移沉积物

英国西北陆缘漂移沉积物的长期记录是通过地震反射资料及钻孔和短芯资料来综合研究的。这些资料表明英国西北陆缘的底层流开始活动时间为晚始新世早期,即在罗卡尔海槽和哈顿－－罗卡尔盆地的一个主要沉降期之后。地震反射剖面反映了上始新统下部坳陷和侵蚀面以及被中－－上新生界沉积物上超的较老地层。后者主要由深海等深流沉积物组成,其保存形态为丘状、长条状和宽阔席状及与波状沉积物相关的漂移沉积物。这些漂流物序列的地震地     

SEDIMENT TRAPPING BY VEGETATIVE FILTER STRIPS

lINTR0DUCTI0NSoilerosionisamaj0rcauseoflanddegradationandwaterpolluti0n.Vegetativefilterstrips(VFS)havebeensuccessfollyandwidelyusedintheUSAf0rremovingsediment(Dillahaetal.,l989;Line,l991;CooperandLipe,l992;R0binsonetal.,l996),s0lids,andnutrientsfromcultivatedland(Magetteetal.,1989)andfeedlots(Y0ungetal.,l978;l980;Edwardsetal.,l983,Edwardsetal.,1997;DickeyandVanderh0lm,l98l),f0rfiIteringrun0fffromdairy(Livingst0nandHegg,l981)andswineproducti0nareas(Sieversetal.,l975;Chaubeyetal.,l9…