A new technique for continuous sphincter pressure measurement

A cannula and conveniently arranged ancillary apparatus designed to assist endotracheal intubation of patients with upper respiratory tract obstruction prior to tracheostomy are described.     

Heat transfer evaluation of the nasal thermistor technique

When analyzing transvalvular and venous flow velocity patterns, it is important to relate them to respiration. An accurate recording of respiratory phase can be carried out with different methods. One of these methods is the use of a thermistor, which reacts to the variation in air temperature, placed in the noise of the patient. The thermistor used has a diameter for 1.0 mm and is of standard bead type. Although small, it has a considerable long time-constant and a long time-delay. The high time-constant gives a low cutoff frequency, well below the respiratory frequency and thereby causing a large phase difference. The thermistor was analyzed with the lumped heat capacity method, where it was easy to study the influence from design parameters, time-dependent air temperature, and velocity. The analysis was extended using the finite element method and the temperature field in the thermistor and the probe was calculated as a function of space and time. These calculations confirmed the result from the lumped model. The result showed that timing of respiration was not accurately obtained with the thermistor analyzed. To improve the timing, it was necessary either to change the measuring method or to use signal processing in order to achieve faster response.     

A new type of oxygen analyzer utilizing a potentiostatic coulometric titration technique

A new type of oxygen analyzer was constructed utilizing the electrochemical oxygen pump: Pt, air/ZrO₂ (+ CaO)/Ar + H₂ + H₂0 gas mixture, Pt. Copper, indium, or tin samples were melted in a circulating Ar + H₂ gas mixture; the oxygen content was then determined within 3 minutes from the change in the electrical current passing through the oxygen pump. The analytical values were highly consistent and reliable despite the fairly low oxygen concentrations in the samples. Neither standard samples nor the establishment of blank conditions was necessary. This type of oxygen analyzer appears to be useful for determining oxygen concentrations less than 1 wt ppm.     

Computerized thermistor technique for indirect studies of esophageal blood flow

1. Intestinal atrophy contributes to the clinical difficulties of patients on parenteral nutrition. Systemic administration of epidermal growth factor reverses this effect, but there is concern over the clinical safety of intravenous administration of growth factors. We therefore investigated whether administration of luminal epidermal growth factor could reverse the atrophy induced in a rat model of parenteral nutrition when epidermal growth factor was given alone or in combination with soya bean trypsin inhibitor to reduce proteolytic digestion of the epidermal growth factor. 2. Infusion of soya bean trypsin inhibitor alone decreased intraluminal tryptic activity by about 90% but did not result in increased proliferation. Intragastric infusion of epidermal growth factor (72 micrograms/day per rat) caused a 26% increase in proliferation (determined by 2-h metaphase arrest) in the duodenum (P < 0.01) when compared with animals receiving 'control' intragastric infusion. However, intragastric epidermal growth factor had no effect on more distal regions of the bowel, probably reflecting rapid proteolysis of the epidermal growth factor by luminal proteases. In contrast, a trophic effect of luminal epidermal growth factor was seen in the duodenum (28% increase, P < 0.01) and jejunum (24% increase, P < 0.05) of animals which had received epidermal growth factor with soya bean trypsin inhibitor. This was probably due to the soya bean trypsin inhibitor decreasing the rate of degradation of epidermal growth factor by intestinal proteases, allowing biologically active epidermal growth factor to reach more distal portions of the bowel.(ABSTRACT TRUNCATED AT 250 WORDS)     

A model for the thermal properties

Thermal properties are important to several applications for powder metallurgy products. For example, liquid-phase sintered tungsten-copper composites are used in microelectronic packaging to obtain a high thermal conductivity in a low thermal expansion material. This article addresses modeling the thermal properties for composites fabricated by liquid-phase sintering. A computational cell is constructed with interlinked phases, consisting of a core of low thermal expansion material (tungsten) and a edge network of high thermal conductivity phase (copper). This structure is used to calculate the composition effects on the coefficients of thermal expansion and thermal conductivity. The results are applied to prior reports on W-Cu and used as a basis to identify several candidate high thermal conductivity systems for future development.     

Problems in timing of respiration with the nasal thermistor technique

Twelve normal control phakic eyes together with a number of other pseudophakic groups each consisting of 6 eyes were enrolled in this study of spatial and quantitative measurement of glare disabilities in the static visual field (Perimetric Glare Test) using an OCTOPUS 500E automated perimeter with an attached glare source. These groups were a 6 mm no hole lens group, a 6 mm 4 hole lens group, a 5.5 x 6.5 mm 2 hole lens group, a 5.0 x 6.0 mm no hole lens group and a diffractive multifocal group. Glare disabilities in the visual field were minimum in the control group. The 6 mm no hole lens group and the diffractive multifocal group showed no statistical significance compared the control group. Groups with the two types of ovoid lens and the 6 mm 4 hole lens group showed a statistically higher degree and a greater extent of glare disabilities in the static visual field than the control group. Careful selection of appropriate patients to receive implants of small efficient optic IOLs, such as IOLs with positioning holes and ovoid lenses, according to the preoperative pupil size under scotopic or mesopic condition and efficient lens optic size are important in order to reduce hole and edge glare. The diffractive multifocal IOLs group showed a slightly higher degree and a greater extent of glare than the control group and the 6 mm no hole monofocal lens group but the difference was very small and statistically insignificant. Therefore the effects of diffractive microstructure on glare disabilities were considered to be slight and clinically acceptable.     

Lumbar lordosis measurement. A new method versus Cobb technique

STUDY DESIGN: A historic cross-sectional study of lumbar lordosis in 199 healthy individuals aged 1-30 years. OBJECTIVE: To evaluate the magnitude and rate of the development of the normal lumbar lordotic curve with age using two methods of measurement. SUMMARY OF BACKGROUND DATA: There is no agreement among spine physicians on the range of the normal lumbar lordotic curve. In certain conditions, such as a tethered spinal cord, a change in lordotic curve may indicate or even precede the onset of neurologic symptoms. Reliable measurements of the lumbar lordotic curve may aid in the early diagnosis and management of these conditions, before irreversible neurologic change ensues. METHODS: The lumbar lordotic curve was measured by the traditional Cobb technique and by a newly designed method, tangential radiologic assessment of lumbar lordosis. The data were subjected to the Morgan-Pitman test for correlated variances to observe which of the two methods was more reliable in measuring the magnitude and rate of change in the lumbar lordotic curve. RESULTS AND CONCLUSIONS: The rate of development of the lumbar lordotic curve appears to be nonlinear, increases during first year of life and during puberty, and reaches a plateau of approximately 50 degrees at maturity. The tangential radiologic assessment of lumbar lordosis method is more reproducible and more reliable in the lumbar lordotic curve, providing a smaller range of normal values (8 degrees-16 degrees less) than the Cobb method.     

A new osteoblast cell culture system for standardized testing of biomaterials

For in vitro testing of new biomaterials cultured fibroblasts are employed. In the case of the agar diffusion test survival of cells is involved in the presence of the material to be tested. Further statements on the biological effects of a biomaterial require the use of cell cultures adapted to the tissue concerned and the underlying problem being investigated. In the present study, an osteoblast cell culture system with which implant surfaces in contact with bone can be tested as required by the relevant standards is described. Test bodies made of titanium, polystyrene or copper were used in the conventional agar diffusion test, and were also overgrown with fibroblasts or a cell line of foetal human osteoblasts. For the agar diffusion test, the test criterion was the extent of the inhibition area on staining with neutral red, while for the overgrowth, the mean cell diameter and the number of cells was employed. The phenotype of the osteoblast cell line was determined immunohistochemically by means of alkaline phosphatase or immunohistologically by means of collagen I and osteocalcin. Calcification was demonstrated using the v. Kossa stain. In the case of the osteoblasts, a differentiation of a collagen I and alkaline phosphatase-positive phenotype over an osteocalcin-positive phenotype to an increase in calcium deposition was shown. As in the case of the agar diffusion test, direct overgrowth also revealed no cytotoxic effect for titanium and polystyrene. In contrast, a cytotoxic effect consisting in a decrease in the number of cells and also a left shift in the size distribution was observed for copper. The standard deviations of the individual tests were less for overgrowth than for the agar diffusion test. The culture system for osteoblast cells thus meets the criteria of the EN/DIN 30993-5 in terms of the quality and accuracy of the results obtained. In addition to excluding direct cytotoxicity, this test system offers a new possibility of examining the influence of the material on cell growth. Consequently, it permits a repeatable examination of proliferation and differentiation of the osteoblasts on each material surface.     

A thermal processing technique for TRIP steels

An investigation was made to determine the effect of thermal cycling between martensite and reverted austenite on the structure and mechanical properties of a Fe-24 pct Ni-4 pct Mo-0.3 pct C TRIP steel. Measurements of hardness, tensile properties, X-ray line broadening, and metallographic structure indicate that repetitive cycling both strengthens the austenite and raises theM _D from below room temperature to above room temperature. It is shown that cyclical thermal processing produces mechanical properties essentially comparable with thermomechanical processing in this particular TRIP steel.     

A new technique for vapor pressure measurement applied to the Fe−Si−Mg system

Since most magnesium additions to nodular cast iron contain a ferrosilicon base, the Fe−Mg−Si system is of particular commercial interest. The purpose of this investigation was to determine the extent of the miscibility between iron and magnesium-rich liquids in the Fe−Mg−Si system and also to determine the magnesium vapor pressure relations within the miscibility envelope. Two-layer melts were equilibrated in specially developed crucibles and sampled under argon pressure up to 15 atm at 2650° and 2750°F. The liquid miscibility gap between the iron-rich and magnesium-rich liquids shows the following relations: at lower silicon levels (5 to 17 pct Si) in the iron-rich layer the magnesium solubility rises slowly from 0.85 to 3 pct. Above 17 pct Si the magnesium solubility increases rapidly, reaching 15.2 pct at 34 pct Si. In the magnesium-rich liquid the iron solubility is little changed (about 3 pct Fe) up to 10 pct Si. Beyond this point the iron solubility rises quickly to reach 21.5 pct at 33 pct Si. Magnesium vapor pressure measurements were made using a boiling technique specifically developed for this investigation. The validity of the method was checked by determining the vapor pressure of pure magnesium over a range from 3 atm to 15 atm. From the data for the two liquid melts, the activity coefficients are calculated. Additional work involving fourth components and temperature effects is described. This paper is based upon a thesis submitted byP. J. Guichelaar in partial fulfillment of the requirements of the degree of Doctor of Philosophy at the University of Michigan.     

The wick catheter technique for measurement of intramuscular pressure. A new research and clinical tool

The wick catheter technique was developed in 1968 for measurement of subcutaneous pressure and has been modified for easy intramuscular insertion and continuous recording of interstitial fluid pressure in animals and humans. Studies in dogs of the anterolateral compartment of the leg in simulation of the compartment syndrome showed the technique to be accurate and reproducible. The wick catheter technique is capable of important clinical applications in the diagnosis and treatment of acute and chronic compartment syndromes.     

大直径反应器测定焦炭热性能的研究

研究了大直径的金属反应器对检测焦炭热反应性和反应后强度数据的影响。结果表明,适当增大金属反应器的直径并不影响焦炭热性能的测量结果,而且有利于提高检测精度。     

A new technique for determining the denture tooth bond

As we learn more about hypertension, it is becoming increasingly apparent that conventional blood pressure measurements are fraught with potential error. Noninvasive ambulatory blood pressure monitoring is proving to be extremely valuable in both diagnosis and treatment. Advancing medical technology has provided small, noninvasive, reliable systems what are well tolerated by patients. The commercial availability of these systems facilitates their use in both clinical practice and in research. There have been legitimate concerns that continuous blood pressure monitoring may add considerably to the costs of diagnosing and treating hypertension. These worries, however, may be misplaced. If there are indeed as many patients being treated unnecessarily as has been suggested by many studies, then the money saved on drugs may well cover the costs of prolonged blood pressure monitoring. Moreover, many subjects can be spared unnecessary therapy. Although much work needs to be done with larger groups of patients followed over longer periods of time, the early experiences with 24-h ambulatory blood pressure monitoring have been extremely encouraging. These procedures have added to our understanding of hypertension and of the agents used in its treatment and are rapidly assuming an increasing importance in overall management.     

A new system for rapid measurement of ATP

The paper introduces a new type instrument for rapid measuring ATP. The system consists of a micromodule ATP sensor and an instrument for measuring weak light transmitted by optic fiber. The micromodule ATP sensor mainly is composed of enzyme membrane, a probe and a bundle of optic fiber. The instrument measuring weak light consists of photomultiplier, high voltage power, pulse amplifier and counter. The instrument was characterized by simple structure, small size, rapid response time (< 5s), high sensitivity (10(-12) mol/L), stable performance (measuring the same sample for 50 times, CV < 5%), long enzyme storage time (> 3 months).     

A technique for measurement of methylmalonic acid in cattle urine

Methylmalonic acid was measured in cattle urine by decarboxylating it to propionate with sulfuric acid and heat and quantifying the propionate so formed by gas-liquid chromatography. Crystalline methylmalonic acid added to cow urine was recovered quantitatively.