Electrical activation

We have seen that molecules must be activated before they can react and that in thermal reactions they are activated by collisions with high-velocity molecules, while in photochemical reactions they are activated through displacement of the outer electrons produced by the absorption of light. Molecules in the gas phase may be activated also by electronic displacement caused by collisions with electrons or ions. This activation may be brought about directly by cathode rays, by electrical discharges of various types, or indirectly by alpha rays and X-rays, which seem to be effective chiefly through the secondary electrons and ions which they produce. 

In view of the enormous amount of electrical energy which is potentially available, it seems strange that more attention has not been paid to fundamental work on the nature of chemical activation by electrons and ions. Such research might lead, ultimately, to applications of practical value. 

The relation between electron velocity and frequency of radiation in experiments involving the emission or absorption of light is given by the fundamental relation 

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In order to remove tlie unwanted electrical activity associated witli deep-level impurities or defects, one can eitlier physically displace tlie defect away from tlie active region of tlie device (gettering) or force it to react witli anotlier impurity to remove (or at least change) its energy eigenvalues and tlierefore its electrical activity passivation). 

Stimulation of the neuron lea ding to electrical activation of the nerve terminal in a physiologically relevant manner should eUcit a calcium-dependent release of the neurotransmitter. Although release is dependent on extracellular calcium, intracellular calcium homeostasis may also modulate the process. Neurotransmitter release that is independent of extracellular calcium is usually artifactual, or in some cases may represent release from a non-neuronal sources such as gha (3). 

One of the more intriguing cardiovascular developments is cardiomyoplasty where implantable technologies are blended with another part of the body to take over for a diseased heart. One company, Medtronic, in close collaboration with surgeons, has developed a cardiomyoplasty system to accompany a technique of wrapping back muscle around a diseased heart which can no longer adequately pump. A combination pacemaker and neurological device senses the electrical activity of the heart and correspondingly trains and stimulates the dorsal muscle to cause the defective heart to contract and pump blood. Over 50 implants have been performed to date. 

Organic solvents have acute narcotic effects. Aromatic and chlorinated hydrocarbons seem to be especially effective. As stated, the combined effect of several organic solvents is usually considered to be additive. However, there is some evidence that the combined effect may in fact be synergistic. The symptoms caused by organic solvents, often called prenarcotic symptoms, resemble those caused by the use of alcohol. A decrease in reaction time and impairment in various psychological performances can be observed. Acute neurotoxicity can also be detected as abnormalities in the electroencephalogram (EEG i, which records the electrical activity of the brain. " ... 

Control and supervision systems should be designed with circuit monitoring and self-diagnostic testing to verify that the field sensors and devices are electrically active and connected. The system should alarm when an electrical fault is detected. 

Polyelectrolytes such as the ion exchange plastics form an interesting group of materials because of their ability to interact with water solutions. They have been used in medical applications involving the removal of heavy metal ions from the human body. They can be used to interact with external electric fields and change their physical properties drastically as is illustrated by the fact that some electrically active liquid crystals are polyelectrolytes of low molecular weight. 

Arrhythmia is either the result of impaired conduction or altered electrical activity. However, in all arrhythmias, conduction and intercellular communication are important since arrhythmia only occurs if the altered electrical activity in one region is transduced to the whole organ. 

Antiarrhythmic drugs can either influence electrical activity of the single cell or can interfere with the spread of activation. 

The axonal membrane is a lipid bilayer in the nerve fibre. Ionic channels and other proteins are located in the membrane to achieve electrical activity. Action potentials are generated and conducted along the membrane. 

Epilepsy is a heterogeneous group of syndromes characterized by abnormal, rhythmic electrical activity of the brain or parts of the brain. The term epilepsy is reserved for chronic diseases, while a single, isolated seizure does not justify the diagnosis of epilepsy. 

The amide local anaesthetic lidocaine may also be used as an antianhythmic for ventricular tachycardia and exra-systoles after injection into the blood circulation. Drugs with high lipid solubility such as bupivacaine cannot be used for these purposes because their prolonged binding to the channel may induce dysrhythmias or asystolic heart failure [3]. Systemically applied lidocaine has also been used successfully in some cases of neuropathic pain syndromes [4]. Here, electrical activity in the peripheral nervous system is reduced by used-dependent but incomplete sodium channel blockade. 

Metabolic diseases In the pancreatic (3-cells, KATP channel derived from >SUR1 and Kir6.2, links cellular metabolism to electrical activity and regulates insulin secretion. Mutations in SUR1 and Kir6.2 that result in loss of Katp channel function have been identified in families with familial persistent hyperinsulinemic hypoglycemia of infancy (PHHI). 

A seizure is an abnormal behavioral (often motoric) activity caused by abnormal electrical activity of the brain. Seizures can be the symptom of a chronic neurological malfunction, i.e. epilepsy, or can appear as single events, e.g. during fever in infants. 

The terms convulsion and seizure are often used interchangeably and basically have the same meaning. A seizure may be defined as a periodic attack of disturbed cerebral function. A seizure may also be described as an abnormal disturbance in the electrical activity in one or more areas of the brain. Seizures may be classified as partial (focal) or generalized. Each different type of seizure disorder is characterized by a specific pattern of events, as well as a different pattern of motor or sensory manifestation. 

An arrhythmia may occur as a result of heart disease or from a disorder that affects cardiovascular function. Conditions such as emotional stress, hypoxia, and electrolyte imbalance also may trigger an arrhythmia An electrocardiogram (ECG) provides a record of the electrical activity of the heart. Careful interpretation of the ECG along with a thorough physical assessment is necessary to determine the cause and type of arrhythmia The goal of antiarrhythmic drug therapy is to restore normal cardiac function and to prevent life-threatening arrhythmias. 

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