铁屑处理镀铬废水的动力学影响因素

本文介绍了铁屑处理镀铬废水中六价铬的反应动力学影响因素。结果表明在固－液比Ｍ／Ｖ＝１．５ｇ／ｍｌ；温度Ｔ＝２０℃；铁屑粒径Ｄ＝１．０－２．０ｍｍ；活化时间Ｔａ＝２０ｍｉｎ的条件下，Ｋ值保持稳定，反应进行得最快，出水水质达到国家排放标准。     

平原地区城市水环境问题及治理

随着我国城市建设的发展，城市水环境问题越来越突出，应通过治理污染源、降低水文效应、制定合理规划等措施，解决平原城市水环境存在的问题。     

睡眠剥夺对大鼠胃运动及相关胃肠激素影响的研究

目的观察睡眠剥夺对胃排空、胃电活动及降钙素基因相关肽(CGRP)和一氧化氮(NO)的影响。方法将192只SD大鼠随机均分为3组，即急性睡眠剥夺组(A组)、慢性睡眠剥夺组(B组)、空白对照组(C组)；每组又随机均分为2个亚组．每亚组32只大鼠，即AI、AII．BI、BII．CI、CII；每个亚组再随平均分为4个小组．每小组8只大鼠。利用放射分析法．使用放射性核素锝(^99m Tc)．采取液相胃排空的方法检测胃的排空，利用浆膜法检测胃电的变化；利用生化法和放免分析法测定大鼠血浆中的CGRP、NO含量。结果急性睡眠剥夺导致胃排空速率改变．随着睡眠剥夺时间的延长，胃的排空速率逐渐降低；胃电活动在餐前逐渐降低．而餐后无明显规律．呈现紊乱状态；随着睡眠剥夺时间的延长血浆中CGRP的水平，逐渐降低，而NO水平却逐渐升高。慢性睡眠剥夺导致胃排空速率降低．但随着睡眠剥夺时间的延长，胃的排空速率未再发生更为明显的变化．呈现低排空状态；胃电活动在餐前、餐后均无明显规律，呈现紊乱状态；血浆中CGRP的水平随着睡眠剥夺时间的延长。呈现低水平状态．但与干预时间的关系不明显；NO水平呈现相对较高状态．且与干预时间关系不明显。结论睡眠剥夺对胃运动有较为明显的影响。急性睡眠剥夺产生的影响相对显著．导致胃运动功能的降低．而且可以引起大鼠血浆中某些胃肠道激素水平的改变；慢性睡眠剥夺对胃运动也产生影响．导致其功能紊乱，而且影响作用较为持久。     

唐山地区水碘分布调查分析

目的摸清唐山地区水源水中碘的分布情况,为碘缺乏病的防治提供基础资料和科学依据。方法以乡为基本单位,每个乡选取东、南、西、北、中5个地理方位的村,每个村采集1～5水样,采用砷-铈接触法测定水碘。结果唐山地区水碘范围在0.1～116.1μg/L,中位数8.0μg/L,其中在0.1～20.0μg/L的占94.2%;沿海地区水井深度与水含碘量无相关性(P>0.01)。结论唐山为碘缺乏地区,不存在局部高碘地域。     

Sleep deprivation hastens the antidepressant action of fluoxetine

Among ten bipolar depressed patients admitted to our psychiatric ward, five patients were treated with fluoxetine alone and five subjects were treated with fluoxetine in association with total sleep deprivation (TSD) in order to evaluate the effect of the interaction between the administration of the serotonergic antidepressant compound fluoxetine and repeated cycles of TSD. Patients treated with fluoxetine plus repeated TSD showed a faster amelioration of depressive symptomatology compared with the other group. We discuss our findings hypothesizing an enhancement in dopaminergic and possibly in serotonergic transmission due to repeated TSD adding to the increase in serotonergic transmission due to fluoxetine medication.     

Blockade of serotonin-2C receptors by mesulergine reduces ocular dominance plasticity in kitten visual cortex

 We have investigated the role of serotonin-2C (5-HT_2C) receptors in modulation of ocular dominance plasticity in kitten visual cortex. A small quantity of the 5-HT_2C receptor blocker, mesulergine, was infused into the visual cortex of one hemisphere of 5- to 7-week-old kittens using osmotic minipumps, while the control hemisphere received vehicle solution. At the same time, one eyelid of the experimental animals was sutured shut. The ocular dominance distributions in the visual cortex (area 17) were assessed using extracellular recording methods after 1 week of combined mesulergine infusion and monocular deprivation. We found that the majority of the neurons remained binocularly responsive in the mesulergine-treated hemisphere, while most of the neurons recorded were either unresponsive or only weakly responsive to the deprived eye in the control hemisphere. Local infusion of mesulergine into the kitten visual cortex thus reduced the shift of ocular dominance that normally occurs in animals of these ages following monocular deprivation. The blocking effect seems to be distance-dependent and therefore dose-dependent: the farther away the recording sites were from the injection site, the fewer binocularly responsive cells were found. These results are relevant to previous findings indicating transient overexpression of 5-HT_2C receptor in visual cortex of kittens at these ages. The data suggest that the 5-HT_2C receptor system may be involved in the formation and modification of ocular dominance columns in the developing visual cortex. Received: 11 December 1995 / Accepted: 9 June 1996     

Characterization of the Oum Er Rbia (Morocco) high basin karstic water sources by using solid state nuclear track detectors and radon as a natural tracer

Uranium and thorium contents as well as radon -activities per unit volume were evaluated inside different water samples by using a method based on calculating the CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs) detection efficiencies for the emitted -particles and measuring the resulting track density rates. The validity of the SSNTD technique utilized was checked by analysing uranyl nitrate (UO₂(NO₃)₂6H₂O) standard solutions. A relationship between water radon concentration and water transmission of different water sources belonging to two regions of the Middle Atlas (Morocco) water reservoir was found. The influence of the water flow rate as well as the permeability and fracture system of the host rocks of the sources studied was investigated.     

Involvement of Serotonin in Developmental Plasticity of Kitten Visual Cortex

During a critical period of postnatal development, neuronal connections in the kitten visual cortex are susceptible to experience-dependent modifications. These modifications are facilitated by the neuromodulators noradrenaline and acetylcholine. To address the question of whether serotonin (5-hydroxytryptamine; 5-HT), the other major neuromodulator in the cerebral cortex, also plays a role in developmental plasticity, we investigated whether interference with serotoninergic transmission in the kitten visual cortex affects ocular dominance (OD) plasticity. The serotonin neurotoxin 5,7-dihydroxytryptamine or the serotonin receptor blockers ketanserin and methysergide were infused into the visual cortex of kittens undergoing monocular deprivation. We found that both methods of disrupting serotoninergic transmission reduced OD plasticity. However, to be effective, the receptor blockers ketanserin and methysergide had to be applied in combination, suggesting that coactivation of serotonin receptor subtypes of both the 5-HT₁ and 5-HT₂ families have a permissive function in OD plasticity. Since activation of 5-HT₂ receptors stimulates phosphoinositide hydrolysis, our data suggest that second messengers from the phospholipid pathway may play an important role in developmental plasticity of visual cortex.     

A model of human sleep homeostasis based on EEG slow-wave activity: Quantitative comparison of data and simulations

EEG slow-wave activity (SWA; spectral power in the 0.75–4.5 Hz band) is a function of the duration of prior waking and, thereby, an indicator of sleep homeostasis. We present a model that accounts for both the declining trend of SWA during sleep and for its variation within the successive nonrapid eye movement (non-REM) sleep episodes. The values of the model parameters were estimated by an optimization procedure in which empirical SWA of baseline nights (16 subjects, 26 nights) served as a reference. A sensitivity analysis revealed the model to be quite robust to small changes (±5%) of the parameter values. The estimated parameter values were used to simulate data sets from three different experimental protocols (sleep in the evening or sleep in the morning after prolonged waking, or extended sleep initiated at the habitual bedtime;n = 8 or 9). The timing of the REM trigger parameter was derived from the empirical data. A close fit was obtained between the simulated and empirical SWA data, and even the occasional late SWA peaks during extended sleep could be reproduced. Minor discrepancies suggest indirect or direct circadian influences on SWA. The simulations demonstrate that the concept of sleep homeostasis as proposed in the two-process model of sleep regulation can be refined to account in quantitative terms for empirical data and to predict the changes induced by the prolongation of waking or sleep.     

The influence of total sleep deprivation on urinary excretion of catecholamine metabolites in major depression

To elucidate the influence of total sleep deprivation (TSD) on catecholaminergic neurotransmission, which is assumed to be disturbed in depression, 9 depressive patients collected consecutive 24-h urine samples prior to (baseline), during (TSD) and following total sleep deprivation (post-TSD). Urine samples were analysed for total MHPG (3-methoxy-4-hydroxyphenylglycol), conjugates of MHPG (glucuronide and sulfate), excretion of HVA (homovanillic acid) and VMA (3-methoxy-4-hydroxymandelic acid). TSD increased the urinary excretion of MHPG-sulfate as a marker of the central norepinephrine metabolism and the excretion rates of VMA and HVA as indices of the peripheral catecholamine metabolism. Patients with higher VMA values prior to TSD reacted worse, and the VMA increase due to TSD was positively correlated with the response. The results demonstrate that TSD, besides acting as a stimulus on the peripheral sympathetic nervous system, influences central nervous noradrenergic neurotransmission, as reflected by the increase of MHPG-sulfate.