Values Of Sp Research Articles

Structure of diamond and diamond like carbon thin films grown by hot-filament chemical vapour deposition technique

Micro-crystalline diamond (MCD) and diamond like carbon (DLC) thin films were deposited on silicon (100) substrates by hot-filament CVD process using a mixture of CH4 and H2 gases at substrate temperature between 400–800°C. The microstructure of the films were studied by X-ray diffraction and scanning electron microscopy. The low temperature deposited films were found to have a mixture of amorphous and crystalline phases. At high temperatures (> 750°C) only crystalline diamond phase was obtained. Scanning electron micrographs showed faceted microcrystals of sizes up to 2µm with fairly uniform size distribution. The structure of DLC films was studied by spectroscopic ellipsometry technique. An estimate of the amount of carbon bonds existing insp 2 andsp 3 form was obtained by a specially developed modelling technique. The typical values ofsp 3/sp 2 ratio in our films are between 1·88–8·02.

Estimation of hydrocarbon solubilities in hydrofluorocarbons

A new solubility parameter, SP, for hydrofluorocarbons (HFCs) has been developed ( SP=1.175 ln( np)+ 0.025 H-0.063 F-0.028α-0.018β where np depends on the molar volume and the molar refractivity; H and F are the number of hydrogens and fluorines, respectively, in the molecule; and α and β are the respective numbers of H-C-F and H-C-C-F connections). Values of SP have been used to predict if an HFC would be a good solvent for various hydrocarbons at 25 °C. Within an isomeric HFC family, the individual HFCs having the greatest solvency for hydrocarbons were those having the maximum separation of fluorines from hydrogens. Hildebrand solubility parameters, δ, are compared with the semi-empirical SP values. Syntheses for 10 new compounds are given: 3,3,4,4,5,5,6,6,7,7-decafluorononane, 1,1,1,2-tetrafluoro-2-(trifluoromethyl)-3-methylbutane, 1,1,1,2,2-pentafluoro-3-methylbutane, 1,1,1,2,2,3,3,4,4-nonafluoro-5-methylhexane, 1,1,1,2,2,3,3,4,4-nonafluoroheptane, 1,1,1,2-tetrafluoro-2-(trifluoromethyl)butane, 1,1,1-trifluoro-3-(trifluoromethyl)butane, 1,1,1,2,2,3,3,5-octafluorohexane, 1,1,1,2,2-pentahydroperfluorooctane and 1,1,1,2,2-pentahydroperfluorodecane.

Sixteenth Canadian Geotechnical Colloquium: Frost heave in soils: concepts and engineering

Frost heave in soils is analysed from a fundamental point of view to predict the development of periodic ice lens formation that is observed in frozen soils. A model of simultaneous heat and mass transfer associated with three new concepts is described and was found to exhibit many of the frost heave features observed in laboratory tests. An efficient frost heave parameter termed the segregation potential, SP, is also described and found to be an adequate input to a general formulation of heat and mass transfer for the prediction of frost heave in soils for both laboratory and field conditions. Representative values of SP depend on the stress and thermal histories of the soil deposit. The SP-based approach can be used for solving two-dimensional frost heave problems and yields stress, temperature, and ice-content distributions with time. Key words : frost heave, soils, segregation potential, simulation, thermodynamics.

Enzymatic Assay of Inorganic Phosphate with Use of Sucrose Phosphorylase and Phosphoglucomutase

We developed a new enzymatic method for the assay of inorganic phosphate (Pi) by using sucrose phosphorylase (SP; EC 2.4.1.7) and phosphoglucomutase (PGM; EC 5.4.2.2). Pi is transferred to sucrose by SP, producing alpha-D-glucose 1-phosphate (G1P) and alpha-D-fructose. G1P is transphosphorylated by PGM in the presence of alpha-D-glucose 1,6-bisphosphate to form alpha-D-glucose 6-phosphate, which is oxidized by NAD+ and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) to form 6-phosphogluconate (6PG) and NADH. Finally, the oxidation of 6PG by NAD+, catalyzed by 6-phosphogluconic dehydrogenase (EC 1.1.1.44), yields D-ribulose 5-phosphate and NADH. Thus two molecules of NADH are formed for each molecule of Pi, and the reaction is monitored at 340 nm. The Km values of SP for Pi and sucrose were 4.44 and 5.31 mmol/L, respectively. The best buffer was 1,4-piperazinediethanesulfonic acid (PIPES) at 50 mmol/L and pH 6-7. Implementing this method with a Cobas-Bio centrifugal analyzer allowed us to measure Pi accurately and precisely.

Serum levels of steroid and placental protein hormones in ectopic pregnancy

The hormonal profiles of extra-uterine pregnancies (EP) were compared with the normal intra-uterine pregnancies (IUP), and threatened abortions (TA) of good outcome. In 45 cases of EP confirmed histologically, maternal serum human chorionic gonadotropin (hCG), pregnancy specific β 1-glycoprotein (SP 1), 17β-estradiol (E 2) and progesterone (P) were measured serially before treatment by enzyme immunoassays (EIA). The same hormones were also determined in the control groups, 26 with normal IUP and 24 with TA. All four hormone levels in EP were significantly lower ( P < 0.01 – P < 0.0001) than in normal pregnancies and threatened abortions of matched gestational age except the hCG and E 2 in the fifth week of pregnancy. The mean values of E 2 and P were found in the normal levels of luteal phase or slightly over them (8th–9th and 9th–10th weeks, respectively). No increase in the hormonal profiles of the above two steroids was noticed between 5 and 10 weeks' gestation in EP. In conclusion: (a) The significantly lower values of hCG and SP 1 in EP were confirmed; (b) the serial and concurrent hormonal measurements assure the verification of EP and the differentiation from normal IUP and TA of good outcome; (c) the ectopic implantation of trophoblast critically reduces its vitability to hCG and SP 1 synthesis and it can only partially compensate for the reduction of corpus luteum function.

Assessment of Threshold and Saturation Pressure in the Baroreflex Function Curve:A New Mathematical Analysis.

The baroreflex function has been assessed with logistic function analysis, a mathematical model suitable for function curves of sigmoid shape. The nonlinear (sigmoid) relationship between carotid sinus pressure (CSP) and systemic arterial pressure (SAP) reflects threshold and saturation of the SAP responses to CSP changes. The threshold and saturation pressures (TP and SP) are often determined by gross inspection from the experimental recordings. Objective and accurate determination of TP and SP may be achieved by mathematical analysis. Kent et al. (Cardiology, Vol. 57, pp. 295-310, 1972) provided equations that estimated SP and TP to be +/- 1.317/k from the midrange CSP (k, the slope coefficient of a curve). Tan et al. (Circ. Res., Vol. 65, pp. 63-70, 1989) recently used an equation to calculate TP based on the consideration that it is about 95% of the maximal SAP. In this report, we elaborated new equations for the estimation of SP and TP, which approximate midrange pressure +/- 2/k. The accuracy of these new equations compared to other equations was tested using various sets of simulation data. In addition, experiments were conducted in anesthetized dogs with isolated carotid sinus. The open-loop CSP-SAP curves were obtained following various holding pressure (HPs) to demonstrate the phenomenon of baroreflex acute resetting. The effects of using different equations on the values of TP, SP, and delta TP/delta HP (extent of resetting) were analyzed. Both simulation and experimental data revealed that the equations of Kent et al. gave rise to values of TP and SP far different from the realistic values. The values of TP calculated by equation of Tan et al. were dependent on the maximal SAP and the slope of the function curve. The TP and SP (+/- 2/k from the midrange pressure of the sigmoid curve) obtained by our new equations were not significantly affected by the maximal SAP and the curve slope. The mathematical analysis may be particularly useful for comparison among various baroreflex curves with different maximal SAP and/or curve slope.

A single-particle model momentum distribution for 4He

The nucleon momentum distribution for 4He is obtained analytically by means of a single particle (SP) potential which contains both an attractive and a repulsive part. It is shown that the values of the momentum distribution eta sp(k) derived in this way deviate considerably at large values of the momentum k from those predicted by the harmonic oscillator model and behave like a negative power of k, becoming closer to the values obtained with many-body techniques.

Solubility product constants of covellite and a poorly crystalline copper sulfide precipitate at 298 K

The equilibrium constant at 25°C for the following reaction has been measured in NaCl media by an indirect method: CuS(cov) + H +(aq) ⇄ Cu 2+(aq) + HS −(qa), K sp = M Cu 2+ M HS − (10 +pH) where CuS(cov) designates synthetic covellite. Values of pK sp are 21.39, 21.04 and 20.95 at NaCl = 0.2, 0.7 and 1.0 M, respectively; the uncertainty in these K sp values is ±0.15. The free energy of formation of covellite, for which published values are discordant, is calculated to be −11.83±0.4 kcal/mole at 298 K (−49.50 ± 1.7 kJ/mole). This value is obtained by extrapolating the meaured pK sp values to infinite dilution with corrections for Cl − complexing. Applying similar Cl − complexing corrections, based on recent measurements by Seward, to previously published solubility data for galena yields a revised pK sp 0 for galena of 12.78. A poorly crystalline precipitate, obtained by mixing Cu 2+ and HS − solutions, yielded a reversible solubility product 3 orders of magnitude greater than that of covellite but about 3 orders of magnitude less than that of a truly amorphous phase, super-cooled liquid CuS. The poorly crystalline phase has not been studied previously. Its bulk composition was Cu 1.18S, but microprobe analysis revealed that it was a partially exsolved mixture of roughly Cu 1.11S and Cu 1.32S (similar to known blaubleibender covellites). It was kinetically unstable, and converted to covellite when thermally annealed or when exposed to polysulfide solutions. Because of its instability, a material of this nature is unlikely to account for the amorphous copper sulfide alleged to occur in the Red Sea Brine deposits. However, it is possible that on short time scales dissolved Cu in sulfidic waters is controlled by metastable, rather than stable phases, as is known to be the case with dissolved Fe.

Influence of freezing mode on frost heave characteristics

Step-freezing and ramped-freezing tests were conducted on samples using a clayey silt passing the 100 sieve with a clay size content of 29% by weight in order to emphasize the influence of various factors such as the rate of cooling, the suction at the frost front and the freezing path. The trends observed in each type of freezing test can be explained using the mechanism of ice lens formation based on changes in the characteristics of the frozen fringe during transient freezing proposed by Konrad and Morgenstern (1980). The experimental program also showed that total heave did not systematically reflect the influence of the various factors but that a consistent trend was obtained when the freezing tests were analysed in terms of the segregation potential, SP. Furthermore, similar values of SP were obtained for small cooling rates independently of the type of freezing.

Neuromodulatory actions of substance P on the muscarinic receptors of the vas deferens of the rat

The response of post-synaptic neurokinin receptors to SP were not changed by pirenzepine or N-methyl-scopolamine. Atropine led to a slight increase in the EC 50 of SP for its post-synaptic neurokinin (NK-A) receptor. In the presence of neostigmine no changes in the Emax and EC 50 values of SP for its post- and pre-synaptic receptor site were observed. Only the muscarinic receptor site were observed. Only the muscarinic receptor antagonists, atropine and NMS, elicited statistically significant increases in the Emax of SP st its pre-synaptic receptor (NK-A). Addition of 7.4–740 nM SP resulted in a decrease in the EC 50 and Emax values of ACh for its post-synaptic muscarinic receptor (M1). Conversely, 740 nM SP produced an increase in the EC 50 and Emax values of ACh at its pre-synaptic muscarinic receptor (M2). Concentrations of 7.4 and 74 nM SP did not produce statistically significant changes in the Emax of ACh for its pre-synaptic M2 receptor.

Persistence of Stream Invertebrate Communities in Relation to Environmental Variability

(1) The persistence of community structure through time was examined for benthic invertebrates at twenty-seven stream sites in southern England by comparing surveys in 1976 and 1984. (2) Persistence in species composition was assessed as Jaccard's Index (JACC) and as the number of the fifteen most abundant species in 1976 still present in 1984 (NUMB). Persistence in species ranking was assessed by Spearman's correlation coefficients at each site between species abundances in 1976 and 1984; both for total species (SPTO) and for the fifteen most abundant species in 1976 (SP15). Such methods were able to reveal genuine change. (3) There were marked changes in 8 years both in species composition and ranking. JACC lay between 0 29 and 0 58 (mode < 0 5) and NUMB between 4 and 15 (mode 11). Of the twenty-seven values of SPTO and SP 15, 21 and 24, respectively, were positive with only 7 and 5, respectively, being significantly different from zero. (4) Ordination and classification of the communities gave similar results for 1976 and 1984. Axis 1 of the ordination in both years was highly correlated with pH and Axis 2 with distance from the stream source. Samples from the same site but in different years separated out together at the first division of the classification but not at subsequent division. (5) A 'press' perturbation experiment was performed when populations of the benthic fish Cottus gobio L. were established at two previously fishless sites. Persistence in community structure did not differ from unperturbed sites. (6) Overall, persistence was greatest at low discharge, upstream sites with cool summer temperature regimes and low, stable pH. We speculate upon the relative importance of biotic and abiotic influences in the structuring of these communities.

Comparison of growth hormone (GH) sleep secretion and responses to pharmacological tests

GH secretion was studied during sleep in 37 short patients (28 males and 9 females) with height from - 2 to - 6.5 SD. No cause of growth retardation was known in anyone of them. A concommitant complete endocrine evaluation was done everytime with at least two pharmacological tests, using ornithine, arginine and/or insulin. The major GH sleep peak level (SP) was compared to the major GH pharmacological peak level (PP). SP ranged from 2.9 to 46 ng/ml (mean ± SD = 15.8 ± 11 ng/ml) and PP from 4 to 30 ng/ml (mean ± SD = 13.9 ± 8.3 ng/ml). SP and PP were correlated, r = 0.50 (p < 0.01). SP was consistantly below 10 ng/ml when PP was below 6 ng/ml. However, if individual values of SP and PP were in the same range in 23 patients (12 normal, 5 borderline and 6 blunted), they showed discrepancies in 14 : a lack of SP in spite of a normal or borderline PP in 3 or the contrary in 2, and a borderline SP in spite of a normal PP in 3 or the contrary in 6. This shows that in very short children, a normal or bordeline GH response to pharmacological stimuli does not prelude a lack or an insufficiency of GH sleep secretion. In such cases, measurement of GH sleep secretion may offer a rationale for a trial course of hGH treatment.

The solubility of calcite, strontianite and witherite in NaCl solutions at 25°C

The solubility of CaCO 3 (calcite), SiCO 3 (strontianite), and BaCO 3 (witherite) has been determined in NaCl solutions from 0.1 to 6 m at 25°C. Activity coefficients estimated from Pitzer's equations with higher order interaction terms (θ and Ψ) were used to extrapolate the results to infinite dilution. Thermodynamic values of pK sp = 8.46 ± 0.03,9.13 ± 0.03 and 8.56 ± 0.04 were found, respectively, for CaCO 3, SrCO 3 and BaCO 3 at 25°C. These results are in reasonable agreement with literature data. Since Pitzer parameters for the interactions of CO 3 2− with Ca 2+, Sr 2+ and Ba 2+ were not used, our results indicate that they are not necessary at low values of P co2 .