脑电波节律同化效应的实验研究

本文介绍了进行脑电节律同化效应的实验系统和方法,并报道了20个受试者的统计实验结果,对节律同化效应的生理和临床意义进行了讨论.     

矩形微生物燃料电池性能的分析

测试阳极液和阴极液的pH值和电导率的变化情况, 分析微生物燃料电池(MFC)的产电过程和能量利用情况, 为改善MFC的性能提供理论依据。试验结果表明: 随着MFC的运行, 阳极液的pH值和电导率呈现下降的趋势, 阴极液的pH值和电导率呈现上升的趋势, 阴极液的pH值比阳极液的pH值大约高0.30?0.50, 阳极液和阴极液的平均电导率变化不大。MFC稳定运行时, 欧姆内阻为29.69 Ω, 极限电流为2.69 mA, 最大输出功率约为0.8 mW, 对应的内阻约为95.72 Ω。铁氰化钾的质量传输是极限电流的限制性因素。能量分析发现, MFC阳极液中91.1%的葡萄糖被其他微生物消耗, 仅有8.9%的葡萄糖用来发电; 而用来发电的葡萄糖的88.5%的能量转化为其他形式的能量, 仅有11.5%的能量转化为电能。     

关于耦合神经元活动时的能量原理

最近美国耶鲁大学的神经科学家们用实验数据表明,哺乳动物大脑皮层中神经信号的传递是一个代价昂贵的能量支出过程,而神经信号的编码是与能量代谢紧密地耦合在一起的,但是到目前为止还无法定量给出神经元活动时的能量函数。在这篇文章中,能量原理被用于神经活动和神经信息处理机制的研究,在电生理实验数据的基础上,建立神经元活动的用能量函数表示的运动方程。结果表明用能量函数表达耦合神经元的阈下电活动和动作电位,数值计算结果与用Hodgkin-Huxley方程所描述的动作电位一致。从而有可能依据能量原理从脑信息处理的角度揭示和理解大脑神经网络系统的信息表现规律。     

性类固醇激素对黄颡鱼雌雄生长二态性的影响

为了研究性类固醇激素在雌雄生长二态性中(Sexual Size Dimorphism, SSD)的作用,文章分析了性类固醇激素对雌雄生长、性腺发育和能量代谢的影响。结果显示:17β-雌二醇(17β-estradiol, E2)显著抑制黄颡鱼的生长,且E2显著促进能量在肝脏中的分配,但在摄食量上无显著影响,所以E2对黄颡鱼生长的抑制是能量分配的差异引起,而不是能量获取差异引起。17α-甲基睾丸酮(17α-Methyltestosterone, MT)显著促进雌鱼生长,但抑制雄鱼生长, MT能显著促进黄颡鱼摄食和肝脏的能量分配,显著抑制卵母细胞的发育和卵巢的能量投入。本研究发现MT通过促进摄食,抑制卵巢发育并且减少性腺发育的能量投入,从而促进雌鱼生长; E2能够显著增加雌雄鱼在肝脏中能量的投入,最终抑制雌雄生长。实验结果只能部分解释实验中观察到的生长差异现象,因此我们需要更进一步从能量的摄入、分配及消耗三方面来研究雌雄生长的二态性。     

不同作物秸秆对辣椒的化感效应

采用室内生物测定、室外盆栽的实验方法,研究了不同大田作物秸秆浸提液、腐解液及腐解物对辣椒的化感效应。结果表明:秸秆浸提液和腐解液对辣椒种子萌发的化感效应不同,浸提液抑制辣椒种子萌发,且随着浸提液浓度的增加,辣椒发芽指数、胚根长显著或极显著受到抑制,其中以大豆秸秆浸提液的抑制作用最强;秸秆腐解液对辣椒种子的萌发总体上表现为促进效应,腐解物对辣椒的株高、茎粗、鲜质量及根系活力均具有促进作用,且与腐解 物的添加量呈正比;不同秸秆腐解物的化感效应大小依次为玉米秸秆>水稻秸秆>大豆秸秆。     

电生理技术在鱼类尾部神经分泌系统研究中的应用

<正>200多年前,Galvani通过神经-肌肉兴奋性实验发现了神经系统与电活动在功能上具有本质的联系[1,2]。此后,众多研究者投入了大量的精力研发电生理设备,逐步开发出多种能够精确测量和控制神经元电活动的仪器,如:放大器、示波器、刺激器、数模/模数转换器、微电极等。现代电生理设备和技术的更新换代为研究单离子通道电     

晋东豫西旱农试验区农业生态系统能流特征

以晋东豫西旱农试验区－－山西省寿阳县宗艾镇宗艾村农业生态系统为研究对象,分析了农田、果园、林业和畜牧业等亚系统能量流动途径、人工辅助能输入、能量产出,能量结构偏差以及能量转化效率等能流特征。结果表明：（１）由于能量投入低,尽管利用效率较高,但能量产出仍处于低水平阶段。农田生态系统的有机能投入和人工辅助能总投入很低,低于１９７９年全国平均水平,但能量产投比较高,增加人工辅助能投入、提高有机能投入比例     

激光与细胞膜相互作用热、电效应的微观机理分析

在细胞膜电偶极矩液晶模型的基础上,用电动力学,量子统计及固体量子理论对激光与细胞膜相互作用的电学及热学效应微观机理进行研究,导出了激光-细胞膜相互作用的极化及其极化驰豫效应和温升效应公式,这些理论研究结果能解释一些相关实验。     

农田生态系统能量投入产出模型及其应用研究

本文在分析农田生态系统能量转化规律的基础上,建立了农田生态系统的能量投入产出模型,提出了确定能量合理投入范围的方法,并结合德清县农业生产实际对此模型和方法进行了初步应用,提出了该县农田生态系统能量投入的优化对策。     

孤束核参与刺激下丘脑室旁核的镇痛作用

本实验用电刺激鼠尾-嘶叫法测痛,观察电刺激下丘脑室旁核的镇痛效应,并采用核团损毁和核团内微量注射药物等方法分析其镇痛通路。实验结果如下:(1)电刺激下丘脑室旁核能产生明显的镇痛效应。同时,放射免疫测定发现脑干加压素含量升高。(2)损毁孤束核能取消刺激下丘脑室旁核的镇痛效应,但对基础痛阈无影响。(3)孤束核内微量注射加压素拮抗剂[d(CH_2)_5 TYr(Me)-AVP]60ng/0.6μl 和加压素抗血清0.6μl 都可明显对抗刺激下丘脑室旁核的镇痛效应。(4)直接在孤束核内微量注射加压素60ng/0.6μl,能模拟刺激下丘脑室旁核的镇痛效应。实验结果表明:电刺激下丘脑室旁核能产生镇痛效应,其机理之一可能是兴奋了下丘脑室旁核中加压素能神经元胞体,后者通过下行投射纤维在孤束核中释放加压素,影响孤束核神经元的活动,从而产生镇痛。     

Electrohydraulic lithotripsy with peroral choledochoscopy.

OBJECTIVE--To determine the efficacy of peroral electrohydraulic lithotripsy performed with an extra large duodenoscope (outside diameter 14.8 mm) and a choledochoscope with a diameter of 4.1 mm (Olympus "mother and baby" endoscope system) in the removal of very large stones from the common bile duct. DESIGN--Prospective study of patients with giant stones in the common bile duct that were resistant to extraction by conventional means. SETTING--Endoscopy unit at a university hospital. PATIENTS--Four women and one man aged 48-82 (mean 66.4 years) with a total of nine stones in their common bile ducts ranging from 2.2 to 3.6 cm in diameter. INTERVENTIONS--Peroral electrohydraulic lithotripsy was performed after intravenous sedation and under antibiotic cover. Two endoscopists took part in each procedure, coordination being achieved by means of a video monitor. The procedures were performed with a Lithotron EL-23 lithotripter and a 3 French lithotripsy probe inserted through the choledochoscope under direct vision. MAIN OUTCOME MEASURE--Complete clearance of the common bile duct confirmed by occlusion cholangiography. RESULTS--All nine stones (mean minimal diameter 2.6 cm; mean maximal diameter 3.1 cm) were successfully fragmented by electrohydraulic lithotripsy, allowing subsequent extraction with the aid of endoscopy and clearance of the common bile duct. A median of three (range two to five) sessions of endoscopic retrograde cholangiopancreatography were required to achieve complete clearance of the ducts. Patients stayed a median of eight days in hospital after lithotripsy (range eight to 14). There were no complications. CONCLUSION--Peroral electrohydraulic lithotripsy offers a safe and effective alternative for the management of patients with large stones in the common bile duct.     

Inactivation of Microorganisms by Electrohydraulic Shock

The electrohydraulic shock treatment of microorganisms was accomplished by discharging high-voltage electricity (8 to 15 kv) across an electrode gap below the surface of aqueous suspensions of the microorganisms. This treatment was effective in destroying Escherichia coli, Streptococcus faecalis, vegetative cells and spores of Bacillus subtilis, and bacteriophage specific for S. cremoris ML1. The presence of added protein in bacterial suspensions resulted in reduced bactericidal action. Water subjected to electrohydraulic treatment retained a certain amount of toxicity when copper-core electrodes were used to apply the treatment. This was caused by copper liberated from the electrode during electrohydraulic discharge.     

Effect of whole-body vibration with different frequencies and intensities on auditory evoked potentials and heart rate in man

Auditory evoked brain potentials (AEP) and electrocardiogram (ECG) were recorded from 9 healthy male subjects during sinusoidal whole-body vibration exposure (WBV) in the longitudinal (+/- az) direction with four frequencies (1 Hz, 2 Hz, 4 Hz, and 8 Hz) and two intensities as well as under non-WBV conditions. The sequences of the different experimental conditions were arranged according to a 9 X 9 Latin Square design. The sound of the electrohydraulic vibrator was masked by a constant noise level. A subtraction technique was used to eliminate vibration-synchronous activity contaminating the electroencephalogram. The AEP amplitude N1-P2 revealed systematic effects of different WBV frequencies and intensities. The amplitude decreased along with an increase in intensity (16 dB) by about 10 per cent. It diminished increasingly with a monotonic trend in the order non-WBV, WBV 8 Hz, WBV 4 Hz, WBV 2 Hz, and WBV 1 Hz. The interbeat-interval histograms computed from the ECG exhibited the highest mean values at MBV of 1 Hz, high intensity, and the lowest ones at WBV of 4 Hz, high intensity. The AEPs are reaffirmed as an informative measure for studying the WBV effect on central nervous information processing, although the modes of action are not yet fully known. Efferent influences on the acoustic input, cross-modality interaction, sensory mismatch, and changes of central nervous activation level are discussed as potential mechanisms.     

Sterilization by electrohydraulic discharges

High voltage electric discharges between two electrodes immersed in a liquid (“electrohydraulic discharges”) inactivate microorganisms suspended in the liquid. The intense pulse of UV radiation emitted from the plasma formed between the electrodes causes most of the bactericidal effects, rather than shock waves, or free radicals or other chemical species formed in the liquid medium. A method of sterilizing materials without contamination from electrode debris is described. Possible applications and limitations of the technique are outlined.     

Identification of the head-neck complex in response to trunk horizontal vibration

A method is proposed for identifying the head-neck complex (HNC) in the seated human body when it is exposed to the trunk horizontal (fore-and-aft) vibration. It is assumed that the HNC only has the anteroposterior (flexion/extension) motion in the sagittal plane. An electrohydraulic vibrator is used as a source of vibration. To generate the trunk horizontal vibration, the trunk of the seated subject is fixed to the seatback. The subjects are exposed to the random vibration at a magnitude of 1.60 ms^-2 rms (root-mean-square) for 50 s. The coherence and frequency response function are then obtained in the frequency range 0.5–3 Hz. The results show that the HNC behavior is quasilinear with a resonance frequency between 1 and 1.4 Hz. Accordingly, a two-dimensional single-inverted pendulum is considered as a model for the HNC. The frequency domain identification method is then used to estimate the unknown parameters, including the HNC viscoelastic and inertia parameters. The model is examined in a time domain using the random vibration. Good agreement is obtained between experimental and simulation results, indicating the reliability of the proposed method.     

Mechanism of the Bactericidal Action Produced by Electrohydraulic Shock

Electrohydraulic shock was shown to produce oxidation reactions which inactivated certain compounds important in cellular metabolism. Enzymes that were inactivated included lactic dehydrogenase, trypsin, and proteinases of Bacillus subtilis. Free sulfhydryl groups and reduced nicotinamide adenine dinucleotide were oxidized. Adenosine triphosphate was destroyed, but deoxyribonucleic acid was not affected. Intracellular material of Escherichia coli lost its ability to absorb at 260 mmu after electrohydraulic shock. The bactericidal mechanism involved appeared to be due to nonselective oxidation reactions produced by high-voltage discharges in water. These oxidation reactions were probably mediated by free radicals produced in the water.     

A simple unconstrained dynamic knee simulator

The design of a simple dynamic knee simulator is described. In the simulator the joint dynamics are reproduced in-vitro in a knee specimen by controlling the time-histories of the tensions in two flexible cables acting as lumped muscle group equivalents, without constraining the natural conjunct and passive motions of the specimen. The two cable tensions acting individually are used to control the active flexion/extension motion, while their simultaneous action is used to control joint compressive force. The characteristics of the electrohydraulic servo system acting under real-time microprocessor control are described. The system performance during simulation of an idealized level-walking function is evaluated.     

An electrohydraulic apparatus for the measurement of static and dynamic properties of rabbit muscles

The apparatus described in this communication enables the force-velocity relationship to be determined for whole rabbit muscles in vivo and their resistance to fatigue to be assessed at specified rates of external work. The ergometer generates constant-velocity motion, controlling a force of up to 50 N, over a range of velocity up to 500 mm/s and a distance of 20 mm. This distance corresponds to the range of shortening of the rabbit tibialis anterior muscle from full plantar flexion to full dorsiflexion of the foot, equivalent to approximately 28% fiber shortening. Activated muscles can be allowed to shorten at constant velocity from any point on their isometric force trajectory. Cyclic releases for fatigue testing can be made at rates up to 30 releases/min over a period of 6-8 h. The timing of the release and return strokes of the ergometer is under the control of a digital programmer that also synchronizes the delivery of activating stimuli to the muscle nerve and trigger signals to the recording equipment. An electrohydraulic design was chosen because it is simpler to engineer than an electromagnetic actuator, is reliable in continuous cyclic use, and can be assembled, at least in part, from available industrial components.     

Static and dynamic bending responses of the human cervical spine.

The quasi-static and dynamic bending responses of the human mid-lower cervical spine were determined using cadaver intervertebral joints fixed at the base to a six-axis load cell. Flexion bending moment was applied to the superior end of the specimen using an electrohydraulic piston. Each specimen was tested under three cycles of quasi-static load-unload and one high-speed dynamic load. A total of five specimens were included in this study. The maximum intervertebral rotation ranged from 11.0 to 15.4 deg for quasi-static tests and from 22.9 to 34.4 deg for dynamic tests. The resulting peak moments at the center of the intervertebral joint ranged from 3.8 to 6.9 Nm for quasi-static tests and from 14.0 to 31.8 Nm for dynamic tests. The quasi-static stiffness ranged from 0.80 to 1.35 Nm/deg with a mean of 1.03 Nm/deg (+/- 0.11 Nm/deg). The dynamic stiffness ranged from 1.08 to 2.00 Nm/deg with a mean of 1.50 Nm/deg (+/- 0.17 Nm/deg). The differences between the two stiffnesses were statistically significant (p < 0.01). Exponential functions were derived to describe the quasi-static and dynamic moment-rotation responses. These results provide input data for lumped-parameter models and validation data for finite element models to better investigate the biomechanics of the human cervical spine.     

The mutagenic effect of hydroxylamine onMycobacterium phlei strain PA

The mutagenic effect of 0.05m and 1m HA onMycobacterium phlei PA was investigated. To establish the mutagenic effect the inactivating effect was studied under the same experimental conditions. Hydroxylamine at a higher concentration (1m) exhibited relatively high mutagenic effect. This was indicated by about 100-fold and 10-fold higher frequency of INH^r and STM^r mutants, respectively (as compared with spontaneous mutations) and induction of auxotrophic mutants. On the other hand, the mutagenic effect of 0.05m hydroxylamine was low under the same experimental conditions. The inactivating effect of a higher HA concentration (1m under given experimental conditions) was considerably higher when using the given model microorganism than that of the lower one (0.05m under the same experimental conditions). This finding does not agree with literature data obtained in other experimental models.