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Parameters Determined (parameter + determine)
Selected AbstractsFrom Micro to Meso: an exercise in determining hydraulic conductivity of fractured sandstone cores from detailed characterization of the fracturesGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2006Salima Baraka-Lokmane SUMMARY Hydraulic conductivities of fractured sandstone bore cores of 0.1 m in diameter are calculated using detailed characterization of the fracture geometry parameters determined using a resin casting technique. The accuracy of the measurements was about 0.25,1.25 ,m with the image size used. The values of the effective fracture apertures vary between 10 ,m and 50 ,m. For modelling purposes the samples are sectioned serially, perpendicular to the flow direction along the cylinder axis. The hydraulic conductivity of individual slices is estimated by summing the contribution of the matrix (assumed uniform) and each fracture (depending on its length and aperture). Finally, the hydraulic conductivity of the bulk sample is estimated by a harmonic average in series along the flow path. Results of this geometrical upscaling compare favourably with actual conductivity measured in hydraulic and pneumatic experiments carried out prior to sectioning. This study shows that the determination of larger-scale conductivity can be achieved, based on the evaluation of fracture geometry parameters (e.g. fracture aperture, fracture width and fracture length), measured using an optical method, at least at the laboratory scale. [source] Prediction of the non-ideal detonation performance of commercial explosives using the DeNE and JWL++ codesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005S. Esen Abstract The non-ideal detonation performance of two commercial explosives is determined using the DeNE and JWL++ codes. These two codes differ in that DeNE is based on a pseudo-one-dimensional theory which is valid on the central stream-tube and capable of predicting the non-ideal detonation characteristics of commercial explosives as a function of the explosive type, rock properties and blasthole diameter. On the other hand, JWL++ is a hydrocode running in a 2-D arbitrary Lagrangian,Eulerian code with CALE-like properties and can determine the flow properties in all stream lines within the reaction zone. The key flow properties (detonation velocity, pressure, specific volume, extent of reaction and reaction zone length) at the sonic locus on the charge axis have been compared. In general, it is shown that the flow parameters determined using both codes agree well. The pressure contours determined using the JWL++ are analysed in detail for two explosives at 165 mm blastholes confined in limestone and kimberlite with a view to further investigate the explosive/rock interface. The DeNE and JWL++ codes have been validated using the measured in-hole detonation velocity data. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of leptin on motility, capacitation and acrosome reaction of human spermatozoaINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 6 2009H. W. R. Li Summary Leptin is a polypeptide hormone with important roles in reproduction. It has been detected in human seminal plasma as well as on human ejaculated spermatozoa. This study aimed at studying the possible role of leptin in regulating human sperm functions. Immunofluorescent staining was used to study the expression of leptin and its receptor. The correlation between the concentration of leptin and soluble leptin receptor (ObRs) in seminal plasma as measured by enzyme-linked immunosorbant assay and sperm motility parameters measured by computer-assisted sperm analyais (CASA) was determined. The effects of recombinant leptin on human sperm motility, capacitation and acrosome reaction as measured by chlortetracycline staing were also studied. Leptin immunoreactivity was demonstrated at the equatorial and neck regions of human spermatozoa, whereas that of ObRs was shown up on the tail. After Percoll separation, spermatozoa with high density had more intense leptin immunoreactivity compared with those with low density. No significant correlation was found between seminal plasma concentration of leptin/ObRs and sperm motility parameters. After incubation with recombinant human leptin for either 3 h or overnight, there was no change in all the CASA motility parameters determined and percentages of capacitated and acrosome-reacted spermatozoa. We concluded that leptin does not have a significant effect on motility and capacitation/acrosome reaction in human ejaculated mature spermatozoa. Its role in male reproduction is yet to be determined. [source] Solid-solid reactions in series: A modeling and experimental studyAICHE JOURNAL, Issue 9 2009A. K. Suresh Abstract Reactions among particulate solid phases are important and abundant in many materials, chemical, and metallurgical process industries. Many of these are reaction networks, and not single-step reactions as normally assumed. There is no theoretical framework available for the analysis of such systems, and single-reaction models derived from the gas,solid literature continue to be used. Formation of cement clinker in the rotary cement kiln is a prime example of the genre, in which mechanistic aspects play an important role in determining energy efficiency and the composition and nature of the phases that form. In the present study, we formulate a model within the ambit of the "shrinking core" class of models, for reactions in series among solid phases. The model shows the presence of one or two moving fronts in the reacting particle, depending on the relative rates of the processes involved. A single Thiele-type parameter controls the model behavior, at once describing the relative rates of the intermediate formation and consumption processes, and the diffusion-reaction competition for the product formation step. The model has been shown to reduce to the well known single reaction models at the limits of low and high values of the Thiele parameter. Experimental data have been obtained on the calcia-alumina system, an important one in cement manufacture, in the temperature range 1150,1250°C. The model has been fitted to these data and the kinetic parameters determined. The comparison bears out the salient features of the theory, and shows that a degree of diffusion limitation exists for the intermediate conversion step under these conditions. The diffusivity values estimated are in the range of 10,19 to 10,18 m2/s and agree with values found in the literature for similar systems. The rate constant for the intermediate conversion step is of the order of 10,6 s,1. This being among the first such determinations, this value awaits confirmation from other studies. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Pharmacokinetics of difloxacin in pigs and broilers following intravenous, intramuscular, and oral single-dose applicationsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2008H. Z. DING Pharmacokinetics of difloxacin, a fluoroquinolone antibiotic, was determined in pigs and broilers after intravenous (i.v.), intramuscular (i.m.), or oral (p.o.) administration at a single dose of five (pigs) or 10 mg/kg (broilers). Plasma concentration profiles were analyzed by a compartmental pharmacokinetic method. Following i.v., i.m. and p.o. doses, the elimination half-lives (t1/2,) were 17.14 ± 4.14, 25.79 ± 8.10, 16.67 ± 4.04 (pigs) and 6.11 ± 1.50, 5.64 ± 0.74, 8.20 ± 3.12 h (broilers), respectively. After single i.m. and p.o. administration, difloxacin was rapidly absorbed, with peak plasma concentrations (Cmax) of 1.77 ± 0.66, 2.29 ± 0.85 (pigs) and 2.51 ± 0.36, 1.00 ± 0.21 ,g/mL (broilers) attained at tmax of 1.29 ± 0.26, 1.41 ± 0.88 (pigs) and 0.86 ± 0.4, 4.34 ± 2.40 h (broilers), respectively. Bioavailabilities (F) were (95.3 ± 28.9)% and (105.7 ± 37.1)% (pigs) and (77.0 ± 11.8)% and (54.2 ± 12.6)% (broilers) after i.m. and p.o. doses, respectively. Apparent distribution volumes(Vd(area)) of 4.91 ± 1.88 and 3.10 ± 0.67 L/kg and total body clearances(ClB) of 0.20 ± 0.06 and 0.37 ± 0.10 L/kg/h were determined in pigs and broilers, respectively. Areas under the curve (AUC), the half-lives of both absorption and distribution(t1/2ka, t1/2,) were also determined. Based on the single-dose pharmacokinetic parameters determined, multiple dosage regimens were recommended as: a dosage of 5 mg/kg given intramuscularly every 24 h in pigs, or administered orally every 24 h at the dosage of 10 mg/kg in broilers, can maintain effective plasma concentrations with bacteria infections, in which MIC90 are <0.25 ,g/mL and <0.1 ,g/mL respectively. [source] Pharmacokinetics of sarafloxacin in pigs and broilers following intravenous, intramuscular, and oral single-dose applicationsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2001H. Z. Ding Pharmacokinetics of sarafloxacin, a fluoroquinolone antibiotic, was determined in pigs and broilers after intravenous (i.v.), intramuscular (i.m.), or oral (p.o.) administration at a single dose of 5 (pigs) or 10 mg/kg (broilers). Plasma concentration profiles were analysed by a noncompartmental pharmacokinetic method. Following i.v., i.m. and p.o. doses, the elimination half-lives (t1/2,) were 3.37 ± 0.46, 4.66 ± 1.34, 7.20 ± 1.92 (pigs) and 2.53 ± 0.82, 6.81 ± 2.04, 3.89 ± 1.19 h (broilers), respectively. After i.m. and p.o. doses, bioavailabilities (F) were 81.8 ± 9.8 and 42.6 ± 8.2% (pigs) and 72.1 ± 8.1 and 59.6 ± 13.8% (broilers), respectively. Steady-state distribution volumes (Vd(ss)) of 1.92 ± 0.27 and 3.40 ± 1.26 L/kg and total body clearances (ClB) of 0.51 ± 0.03 and 1.20 ± 0.20 L/kg/h were determined in pigs and broilers, respectively. Areas under the curve (AUC), mean residence times (MRT), and mean absorption times (MAT) were also determined. Sarafloxacin was demonstrated to be more rapidly absorbed, more extensively distributed, and more quickly eliminated in broilers than in pigs. Based on the single-dose pharmacokinetic parameters determined, multiple dosage regimens were recommended as: a dosage of 10 mg/kg given intramuscularly every 12 h in pigs, or administered orally every 8 h in broilers, can maintain effective plasma concentrations with bacteria infections, in which MIC90 are <0.25 ,g/mL. [source] The influence of chain-ends on the thermal and rheological properties of some 40/60 PES/PEES copolymersPOLYMER ENGINEERING & SCIENCE, Issue 8 2009Lorenzo Abate Four random, differently ended (Cl, NH2, OH, and COO,), polyethersulfone/polyetherethersulfone (PES/PEES) copolymers were studied to investigate the influence of chain ends on thermal and rheological behaviors. The number average molar mass (Mn , 9500 g·mol,1) and the PES/PEES ratio (40/60) of all copolymers investigated were checked by 1H NMR spectra. Thermal degradations were carried out in the scanning mode and initial decomposition temperatures (Ti) and activation energy values of degradation (Ea) were obtained. Glass transition temperature (Tg) was determined by differential scanning calorimetry and complex viscosity (,*) by rheological measurements in isothermal heating conditions (T = 270°C). All parameters determined were largely affected by copolymer chain ends and decreased according to the same order, OH > NH2 > Cl > COO,. The results were discussed and interpreted. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] A Gadolinium-Binding Cyclodecapeptide with a Large High-Field Relaxivity Involving Second-Sphere WaterCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2009Célia Abstract A new cyclodecapeptide incorporating two prolylglycine sequences as ,-turn inducers and bearing four side chains with acidic carboxyl groups for cation complexation has been prepared. Structural analysis in water by 1H,NMR spectroscopy and CD shows that this template adopts a conformation suitable for the complexation of lanthanide ions Ln3+, with its carboxyl groups oriented on the same face of the peptide scaffold. Luminescence titrations show that mononuclear Ln,PA complexes are formed with apparent stability constants of log,,110,6.5 (pH,7). The high-field water relaxivity values arising from the Gd,PA complex at 200,500,MHz have been interpreted with molecular parameters determined independently. The experimentally determined water relaxivities are undoubtedly 30,% higher than the expected values for this complex with two inner-sphere (IS) water molecules and a medium-range rotational correlation time (,R=386,ps (±10,%)). This led us to propose the existence of a large second-sphere (2S) contribution to the relaxivity caused by the interaction of water molecules with the hydrophilic peptide ligand by hydrogen-bonding. [source] | |||||||||||||