Best Operational Conditions Research Articles

Limitation of experimental capabilities for interfacial studies

Solar energy technologies involve components and devices whose operation depend critically on various interfaces. To obtain optimum performance from these devices it is essential to be able to analyze in some detail the characteristics of these interfaces. In principle, there now exist enough experimental techniques to determine essentially every parameter that might need to be known about the surface of a solid or the S-S interface. In practice, we are clearly not yet at that stage. The reason is not for lack of experimental techniques or theoretical approaches but primarily because of the limitations of these approaches. The variety of techniques at present available indicates that improvement will probably come from alterations in existing techniques rather than in the development of new ones. For characterizing solar interfaces, in situ measurements are critically necessary and, because very few probes are available for making relevant measurements, considerable effort should be devoted to developing in situ probes. The most popular tool for determining the elemental composition at S-G and S-S interfaces is AES in which the electrons resulting from radiotionless de-excitation of atoms are energy analyzed. Almost all peaks in an Auger spectrum can be unambiguously identified. However, there are various limitations. The sensitivity level under good normal operating conditions is usually in the 0.1%–1% range of the surface (1 nm) region. Insulating surfaces often become charged, causing severe and irreproducible shifts in the spectrum of detected elements. Many materials are subject to electron beam effects which can cause irreversible rapid change in the surface being studied. For example, the preferential removal of oxygen is observed from many metal oxides, even from apparently very stable materials such as alumina. Another useful approach is to use an ion beam as a probe for surface elemental composition, leading to the techniques of SIMS and ISS. The major limitation of ion probes is the destruction of the substrate, either for the analysis (SIMS) or because of ion bombardment (ISS). The chemical nature of the various elements is also of interest, e.g. whether the detected silicon signal is derived from elemental silicon, SiO, SiO 2, part of another silicon compound or some combination of these. For some materials, AES can answer some of these questions, but not in every case. In principle, XPS (also called ESCA) can answer these questions, but in practice the valence state may not be identifiable. In addition to knowledge about the two-dimensional surface lateral spatial distribution of components at the interface, precise knowledge of where individual surface atoms are located relative to each other, i.e. specific surface structure, might be required. Answers to the latter question might result from using LEED, EXAFS, EELS etc. However, to make these experimental techniques useful requires the addition of considerable non-trivial theoretical calculations. The questions of crystallinity can usually be answered by LEED. Unless detailed current-voltage curves are obtained and combined with elaborate theoretical analysis, only limited structural information can be gleaned from the data. The morphology of the surface is of interest. Here, SEM is clearly the popular technique being used. It can provide considerable information up to the limit of resolution of the instrument, which is usually about 10 nm under good operating conditions. However, care must be taken in the interpretation of SEM images or photographs to avoid reaching false conclusions. In all the approaches mentioned above, the power density effects of the beam probes must always be taken into account and can often be a severe limiting factor. Specific details about limitations of the popular techniques as well as observations about other techniques are considered.

Temperature Dependence of the Hydrogen Maser Wall Shift in the Temperature Range 295-395 K

Possible ways to improve the hydrogen maser accuracy are stated. Use of a special bulb, made of quartz, allowing simulation of two different mean diameters is proposed. It is experimentally proved that it allows one to achieve very good operating conditions in the temperature range 300-395 K. Measurement, with this bulb, of the temperature dependence of a FEP 120 teflon coating is reported. A change of FEP 120 properties is observed at a temperature of 360 K. This is confirmed by operating a hydrogen maser with a classical spherical bulb. A null of the mean phase shift per collisions occurs at a temperature of 385 K. Good precision of wall shift measurements made with the special bulb, in the temperature range 300-360 K allowed one to achieve an accuracy of 6 × 10-13 and to determine the unperturbed hydrogen hyperfine transition frequency fH with a precision of 7 × 10-13. The result is fH = 1420405 751.773 ± 0.001 Hz.

KETAMINE FOR PEDIATRIC CARDIAC ANESTHESIA

Eighty-five patients ranging from 12 h to 7 years of age were included in this study. In the first group 35 cases received ketamine, gallamine and oxygen for surgery on the great vessels. Ketamine provided satisfactory analgesia and amnesia. Heart rate did not change significantly. Gallamine gave additional safety in the prevention of bradycardia. One hundred per cent oxygen increased oxygen saturation and made more oxygen available for the tissues. The combination secured favorable conditions even in cases of sevre right to left shunt. Seven patients developed some degree of bradycardia, requiring treatment. All but one responded to epinephrime infusion. The one who did not improve died on the table. There were 6 additional deaths during the first 48 postoperative hours. Fifty infants and children received pentobarbital and morphine premedication and ketamine, pancuronium, nitrous-oxide oxygen anesthesia for open heart surgery. Cardiovascular stability with good operating conditions characterized the course of anesthesia. The increase in systolic and diastolic blood pressures and heart rate was small after induction. Further changes in these parameters during anesthesia were statistically insignificant. Perfusion pressure during cardio-pulmonary bypass was well maintained. The addition of 50 per cent nitrous oxide to inhaled oxygen significantly potentiated the duration of hypnosis and analgesia proved by ketamine. Mechanical ventilation was facilitated in both groups by the analgesia extending well into the postoperative period. There were 6 deaths in the first 48 postoperative hours in this group. The state of consciousness at the end of anesthesia and postoperative conditions of all 85 patients were comparable with that found with other agents. The techniques described provided suitable alternatives to the anesthetic management pediatric cardiac surgery.

Method of Choice

Recently I read two articles that dealt with selection of anesthesia for one particular operation; each author called his system of choice. The two methods were different: one author prescribed three or four agents; the other, five. I have done the same thing (just as well, I think) with one or two agents. Why each author called his technique a method of choice was hazy; both claimed to provide good operating conditions, and that was all. Neither paper offered statistical comparisons with other methods or counting of cases; nothing that might have been measured was measured. Clearly, the words method of choice had no justification, serving only to irritate the reader. There are few methods of choice, unless laid down in documented studies by serious workers. The use of the words method of choice without statistical study and proved significance, and without justification, is deplorable. All too often,

Use of methohexitone, fentanyl and nitrous oxide for short surgical procedures.

An anaesthetic technique for unpremedicated patients undergoing minor surgery is described. After the administration of atropine and fentanyl, anaesthesia was induced with methohexitone and maintained with nitrous oxide supplemented when necessary by further small doses of methohexitone. This technique provided good operating conditions and was free from major complications. Recovery was rapid and pleasant.

Evaluation of 350 sciatic blocks in rheumatoid foot surgery.

Sciatic block with Mepivacaine (3-4 mg/kg) revealed successful in 91.9% of 340 rheumatoid patients with Keller/Clayton operation. In unsufficient blocks (8.1%) supplementary anesthesia by femoral nerve block, reblocking the sciatic nerve or local anesthetics secondarily gave good operating conditions. In three cases it was necessary to use additional spinal anesthesia. The concomitant sympathetic block gives an immediate cessation of sweating and a long lasting evaluation of skin temperature.

Anaesthesia in patients with phaeochromocytoma.

The authors' technique of balanced neuroleptanaesthesia with droperidol, fentanyl, nitrous oxide, pancuronium and nitroprusside is outlined. It is suggested that this is the anaesthetic method of choice for the surgical removal of catecholamine secreting tumours since it is associated with good operating conditions and an uneventful post-operative period.

Building vibrations

The rapidly advancing technology of the electronic industry has gone beyond the state of the art of Building Designer. Smaller and smaller geometries in the semiconductor field have necessitated more and more high‐powered magnifications. At present, telescopes with magnifications of 500 to 600 are standard practice. Operators of telescopic equipment working at this magnification are required to align geometries, and vibrations must be kept to a level which will not be noticeable so as to disturb the operators. In as much as it is impossible to remove all vibration that can be caused by such sources as traffic, building mechanical equipment, elevators, footfalls, manufacturing equipment, etc., it has become necessary to attempt to develop maximum amplitudes of structural motion that will still allow good operating conditions.

Preventive Health Maintenance for Executives

Although management personnel recognize the value of keeping physical plants in good operating condition, the realization that often they do not likewise understand their responsibility in keeping human resources in proper operating condition is disturbing. Executives need to evaluate their own physical fitness and follow a plan in order to protect the firm9s investment in its human resources. To these ends, the authors discuss preventive maintenance for human resources and hypokinetic diseases and obesity and present a self-evaluation technique for determining physical fitness.

CLINICAL EXPERIENCE WITH SUBANESTHETIC KETAMINE

Forty thermally injured patients received 150 intramuscular (I.M.) administrations of sub-anesthetic ketamine for debridement and dressing changes. Satisfactory analgesia lasting approximately 15 minutes, complete amnesia, and good operating conditions were achieved. Tolerance to ketamine developed in all patients receiving more than two exposures. Recovery was prompt, with resumption of oral alimentation in approximately 1 hour. Side effects were minimal, and no major complications occurred.

Clinical experience with subanesthetic ketamine

Forty thermally injured patients received 150 intramuscular (I.M.) administrations of sub-anesthetic ketamine for debridement and dressing changes. Satisfactory analgesia lasting approximately 15 minutes, complete amnesia, and good operating conditions were achieved. Tolerance to ketamine developed in all patients receiving more than two exposures. Recovery was prompt, with resumption of oral alimentation in approximately 1 hour. Side effects were minimal, and no major complications occurred.

A NEW TECHNIQUE FOR MICRO-LARYNGEAL SURGERY IN INFANTS

General anesthesia for microsurgery on the larynx in infants poses many problems if one is to provide good operating conditions for the surgeon and adequate safety for the infant. In the technique presented here the infants were anesthetized with inhalational agents, then a 16-gauge plastic catheter was placed between the cords. With the infant paralyzed the lungs were ventilated with close to 100 percent oxygen by intermittently blowing oxygen at high pressure from the catheter. Anesthesia and paralysis were maintained with intravenous agents. The surgeon operated with a virtually unobstructed field. The child was adequately ventilated and the possibility of inhalation of blood or debris was minimized, as was the likelihood of the spread of neoplastic conditions down the trachea.

Clinical Experience With Subanesthetic Ketamine

Forty thermally injured patients received 150 intramuscular (I.M.) administrations of sub-anesthetic ketamine for debridement and dressing changes. Satisfactory analgesia lasting approximately 15 minutes, complete amnesia, and good operating conditions were achieved. Tolerance to ketamine developed in all patients receiving more than two exposures. Recovery was prompt, with resumption of oral alimentation in approximately 1 hour. Side effects were minimal, and no major complications occurred.

A new technique for micro-laryngeal surgery in infants.

AbstractGeneral anesthesia for microsurgery on the larynx in infants poses many problems if one is to provide good operating conditions for the surgeon and adequate safety for the infant. In the technique presented here the infants were anesthetized with inhalational agents, then a 16‐gauge plastic catheter was placed between the cords. With the infant paralyzed the lungs were ventilated with close to 100 percent oxygen by intermittently blowing oxygen at high pressure from the catheter. Anesthesia and paralysis were maintained with intravenous agents. The surgeon operated with a virtually unobstructed field. The child was adequately ventilated and the possibility of inhalation of blood or debris was minimized, as was the likelihood of the spread of neoplastic conditions down the trachea.

Experiences with a technique of neuroleptanalgesia for bronchography.

The use of a mixture of 2 mg phenoperidine and 5 mg droperidol as an adjunct to topical anaesthesia for bronchography, with or without prior bronchoscopy, is reported in 100 adult patients. Given slowly over 2 to 10 minutes this produces good operating conditions in the majority of patients. However, if parenteral pethidine or diazepam are used as premedication, patients may be too drowsy to co-operate with changes in posture. In the absence of excessive sedation respiratory depression will respond to the simple expedient of asking the patient to breathe. It is recommended that atropine alone be given as premedication, perhaps with oral diazepam in apprehensive patients. Despite the good operating conditions most patients remembered the procedure and half of them found it to be unpleasant.

WAYS TO IMPROVE OF THE AGRICULTURAL COMPLEX ENGINEERING SYSTEM FOR AGRICULTURAL MACHINERY MAINTENANCE

The need of agricultural producers in services of the engineering system providing technical service throughout all life cycle of agricultural machines can be considered as economically reasonable and necessary engineering activity in agroindustrial complex. The implementation of technological processes of maintenance and recovery parameters of the technical condition of agricultural equipment with appropriate quality is possible only subject to the availability of specialized enterprise engineering systems in agro-industrial complex intelligent technological equipping a specific item. For keeping agricultural equipment in good operating condition and parameters of its technical condition it is necessary to use the full range of repair and service impacts that damage tolerant repair and maintenance. The work suggests measures to improve the engineering and technical system (ITS) in the agro-industrial complex of Russia. It is shown that at present the system is characterized by a weakening in the quantity and quality of the fleet of agricultural machines, which negatively affects the material and technical support of agricultural producers. To positive change of the situation it is proposed as a first-priority measure - the creation of innovative centers for high-quality repair of equipment and its components. Examples of planning of such centers with appropriate resource-saving environmentally oriented utilization of agricultural machinery are given.

Elective Circulatory Arrest During Neurosurgery for Basilar Artery Aneurysms

The results of surgical treatment of basilar artery aneurysms have been poor compared to those after treatment of intracranial aneurysms in other locations. In order to facilitate the neurosurgical approach to this lesion, moderate hypothermia has been combined with circulatory arrest. Arrest was induced by open-chest ventricular fibrillation in five patients. Repeated intermittent cardiac massage for one minute following three to four minutes of arrest maintained tissue nutrition while still providing the neurosurgeon with good operating conditions. Careful monitoring of the patients' vital functions together with accurate correction of the blood pH changes resulted in rapid cardiovascular recovery following anesthesia and surgery.

Elective circulatory arrest during neurosurgery for basilar artery aneurysms

The results of surgical treatment of basilar artery aneurysms have been poor compared to those after treatment of intracranial aneurysms in other locations. In order to facilitate the neurosurgical approach to this lesion, moderate hypothermia has been combined with circulatory arrest. Arrest was induced by open-chest ventricular fibrillation in five patients. Repeated intermittent cardiac massage for one minute following three to four minutes of arrest maintained tissue nutrition while still providing the neurosurgeon with good operating conditions. Careful monitoring of the patients' vital functions together with accurate correction of the blood pH changes resulted in rapid cardiovascular recovery following anesthesia and surgery.

A PIG Ion Source of (He3)++ for the Van de Graaff Accelerator

A PIG type ion source for the Van de Graff accelerator has been developed for the production of (He3)++ ion. Under good operating conditions, (He3)++ ion current amounts to 3% (about 9 µA) of the (He3)+ ion current. The main emphasis in design in to produce the strong magnetic field in the arc chamber.

GENERAL OROTRACHEAL ANESTHESIA FOR BRONCHOSCOPY.

Bronchoscopy was made under general orotracheal anesthesia by introducing into the trachea a cuffed No. 4 or 5 Magill endotracheal tube followed by the bronchoscope. Intermittent positive pressure respiration with nitrous oxide and oxygen was used. The technique ensured good operating conditions without time limit. PCO2 in arterialized capillary blood was analysed in seven patients during the procedure; in some samples there was a minor rise in CO2 tension.