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Management of patients with isolated ventricular septal defect (VSD) requires information regarding pulmonary artery pressure (PAP). The purpose of this study was to evaluate the individual predictive value of noninvasive methods for assessment of PAP and to determine if any combination of techniques significantly improved their predictive power. We reviewed the clinical history, electrocardiogram, and echocardiogram of 31 patients (age 1.9 ± 1.73 years) who underwent catheterization for isolated VSD. Noninvasive data were compared for patients with mean PAP <20 mmHg (group 1) and those with mean PAP ≥20 (group 2) at catheterization. Fourteen (45%) patients were in group 1 and 17 (55%) in group 2. Doppler estimation of VSD gradient, right ventricular hypertrophy by echocardiogram, interventricular septal orientation, and VSD size had predictive value for elevated mean PAP (p< 0.01). All patients (n= 6) with normal findings in all four variables had normal PAP. All patients (n= 12) with at least three of four abnormal findings had elevated PAP. Six patients in group 1 had at least one variable that incorrectly predicted high PAP, whereas 3 patients with normal findings on three of the four variables nevertheless had elevated PAP. No single noninvasive variable accurately predicted PAP in all cases. However, normal findings for all four significant variables did predict normal PAP and suggest that cardiac catheterization is unnecessary in that setting. However, any other combination of normal and abnormal findings for the four significant variables did not reliably predict PAP and such patients may require catheterization to directly measure PAP.

1.As the result of carbonitriding the hardness of high speed samples increases an average of HV 200–300.2.The optimum carbonitrided case thickness, 0.02–0.03 mm, is reached in 10–15 min for R6M5, R18F, R12F2K8M3, and R12F3 steels and in 20–25 min for R6M5K5 and R9M4K8 steels.3.After carbonitriding cutting tool life increases by three to four times.4.The carbonitriding process does not require complex equipment and makes it possible to obtain a high rate of heating and to decrease thermal stresses and warping of the tool.

The authors give the results of an investigation of full-scale slide bearings made of material based on PTFE in vacuum under conditions which are realized in ordinary engineering. They show that unfilled PTFE possesses insufficient wear resistance, and that very hard mineral fillers cause a marked rise in the coefficient of friction owing to frictional heating.

The study of glucose uptake by rat epididymal fat has demonstrated that the effect occurs at concentrations above 10µ units per ml; it then increases progressively up to a concentration of 100,000µ units per ml. Within a range of concentration from 50 to 100,000µ units per ml, there is a linear relationship between the logarithm of the insulin concentrations in the medium and its effect; the correlation co-efficient is +0.889. A regression equation was calculated which gave a mean error for the determination of the insulin concentration of 1.78. Thus, this method is not only simple, but is also sufficiently precise for the determination of insulin concentrations in an incubation medium.

Conclusions 1.When plastic deformation accumulates in EI612 austenite steel, the relaxation is speeded up and in pearlitic 20Kh1M1F1 steel the resistance to relaxation increases continuously and the decrease in stresses is slowed down, almost to the point of total utilization of the ductility (0.90–0.95%).2.Failure when the stresses are relaxed or during combined relaxation-creep tests is due to exhaustion of the ductility. The degree of approach to failure under conditions of relaxation of smooth specimens can be described by the quantity ?pl/df, which may be used as a criterion for the damage. The ductility for any time is 1 - ?pl,/df.3.During relaxation the time prior to failure calculated by summation of the relative period over which the stresses act is equivalent to the time prior to failure in long-term rupture tests.

1.Creep tests over periods of 25000–114000 h under stresses equal to or somewhat higher than the theoretical creep limit showed that a constant creep rate is really a variable creep rate. Therefore, the second creep period can be characterized only by some average creep rate.2.The “constant” creep rate and the length of the second period result from the particularities of structural processes occurring in the steel. In heat-resistant steel under low stresses the plastic deformation accumulated up to the beginning of the third period is 0.2–0.5% regardless of the value of the minimum creep rate. The time preceding this degree of deformation determines the length of the second creep period.3.One must consider the creep limit to be the stress which induces a certain degree of deformation after a given period of time at a given temperature. The theoretical creep limit determined from the constant creep rate of 1·10-5 %/h is an undependable characteristic of the resistance of a part to creep during its working life.

Insulin activity of the blood in female and newborn rabbits was determined at the immediate post-partum period by the method of glucose uptake by the isolated epididymis fat of rats. In control animals the insulin activity of the blood in female rabbits was 809 µ U/ml. Upon administration of alloxan on the 12th day of prenancy in a dose of 200 mg/kg,diabetes was compensated by the time of delivery in almost all the rabbits; the insulin activity of the blood was increased (1057 µ U/ml). In rabbits which received a similar dose of alloxan on the 22nd day of pregnancy, the insulin activity of the blood after delivery was 1225 µ U/ml and in newborn rabbits 1214 µ U/ml. Consequently, alloxan diabetes, existing for a brief period of time and compensated by the time of delivery, may cause hyperfunction of the insular apparatus of the fetus only if it existed at the moment of functioning of the fetal insular apparatus, i.e. at the end of pregnancy.

The process of friction and wear in the presence of vibration has been investigated on the range of relatively high loads and vibration amplitudes. It is shown that the use of Teflon-based composites completely eliminates damage to the contact surfaces as a result of fretting corrosion.

Insulin was extracted from blood plasma on strong sulfacationic ion-exchange resin, trade mark SDV-3, 60–80 mesh, swelling coefficient 3.0 in hydrogen form. Bio-assay for insulin activity was performed by rat epididymal fat pad technique. Insulin activity as assayed in maternal venous and umbilical venous blood at birth and mean error values of insulin activity were 226±26.3 and 223±25.7 µU/ml respectively. There was no difference between insulin activity of maternal venous, retroplacental and umbilical venous blood either in mean values or individually. Since placenta is impermeable to insulin it is presumed that at birth insular function of fetus is relatively high and roughly equal to that of adult women at the end of pregnancy.

A fraction of urine isolated by means of ion-exchange chromatography caused enhanced uptake of glucose by rat diaphragm and epididymal fat pad, and intensified respiration of the latter. Concentrated solutions of the fraction induced hypoglycemic convulsions in mice. The yield of activity in the urine rose following administration of glucose to healthy individuals. The activity was not abolished by treatment with acids, but was abolished by alkali treatment, and by heating at 100°, as well as by thiols. On these criteria, it is concluded that the urinary fraction examined contained insulin.

The plasma insulin was fractionated on strong sulfocationites: IR-120 in sodium form and SDV-3 in hydrogen form; the insulin bio-assay was carried out according to the glucose uptake of rat epididymal fat pad. The results were expressed as extra glucose uptake, in mg/g/3 h. In 12 nonpregnant fasting females of child-bearing age the activity of free insulin was 1.391±0.282 and that of bound insulin-3, 162±2.267 mg/g/3 h. In 18 women at 24–36 weeks of pregnancy the values were 2.724±0.410 and 2.983±0.342 mg/g/3h respectively. At the time of delivery in 12 women the content of free insulin in maternal venous blood was 9.948±0.313 and that of bound insulin-1.434±0.352; in the blood of umbilical vein the values were 2.030±0.470 and 2.597±0.476 mg/g/3 h respectively. The increased level of free insulin in pregnancy is significant (P<0.02). There was a positive correlation of bound insulin in pregnancy is significant (p<0.02). There was a positive correlation of bound insulin levels in maternal and fetal blood (r=0.440; p=0.05) and a negative and not significant correlation of free insulin levels (r=0.404; P>0.05). The latter fact points to the insulin impermeability of placenta.

Results are given from studies on sets of pairs which have a coefficient of friction below 0.1 at medium specific loads and low rates of relative slippage. It is shown that this may be accomplished by using materials with different chemical structures in the pair, for example, Teflon and low-density polyethylene, or a self-lubricating material, for example oil-impregnated modified wood in a pair with a polymeric counterbody.