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F Value (f + value)
Selected AbstractsA protocol to estimate the release of anthropogenic hydrocarbons from contaminated soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Raymond C. Loehr Abstract An operational protocol, appropriate for a tier 1 or tier 2 type relative risk evaluation of a site that has polycyclic aromatic hydrocarbon (PAH) or petroleum hydrocarbon impacted soils, was developed to estimate the fraction of anthropogenic hydrophobic hydrocarbons that will be released rapidly from such soils. The development of this protocol used over 400 datasets from 40 different field samples to establish and verify the operational protocol. The datasets resulted from four-month kinetic desorption studies of these field samples. Based on the chemicals evaluated, the protocol has greatest application to two, three, and four ring-PAH and to diesel range aliphatic hydrocarbons. The protocol is a simple batch desorption analysis that uses established methods and is conducted for 7 d. The protocol results were verified with specific correlation relationships (r2 = 0.81 to 0.96) to estimate the rapidly releasing fraction (F value) that is obtained in a full, four-month chemical release evaluation. [source] CHANGES IN TEXTURAL CHARACTERISTICS OF PANEER IN READY-TO-EAT CANNED PANEER CURRY DURING STORAGEJOURNAL OF TEXTURE STUDIES, Issue 2 2006K. JAYARAJ RAO ABSTRACT Paneer is an Indian soft cheese obtained by coagulating hot milk using citric acid or vinegar, pressing the hot coagulum and cooling by dipping in chilled water. In this study, paneer curry with a water activity (Aw) of 0.95 and a pH of 5.0 was prepared using ingredients like tomatoes, onions, cream, milk powder, curds and different spices, then canned at an F value of 0.80 (lethality). The product was stored at 15, 30 and 45C, and change in textural characteristics during storage was studied. Cohesiveness and chewiness increased, but hardness decreased. These changes were attributed to continued changes in texture initiated by frying of paneer and canning process. These were also linked to Maillard browning which progressed during storage as measured by hydroxymethylfurfural content. These changes were found to be slower vis-à-vis those observed in the product, which was sterilized at conventional F value of 15.0 (control) (Aw = 0.98 and pH 5.2). [source] Dose-dependent pharmacokinetics and first-pass effects of mirodenafil, a new erectogenic, in ratsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 6 2009Young H. Choi Abstract The pharmacokinetics of mirodenafil and its two metabolites, SK3541 and SK3544, after intravenous (5, 10, 20 and 50,mg/kg) and oral (10, 20 and 50,mg/kg) administration of mirodenafil, and the first-pass effect of mirodenafil after intravenous, oral, intraportal, intragastric and intraduodenal (20,mg/kg) administration of mirodenafil were evaluated in rats. The pharmacokinetics of mirodenafil and SK3541 were dose-dependent after both intravenous and oral administration of mirodenafil due to the saturable hepatic metabolism of mirodenafil. After oral administration of mirodenafil, approximately 2.59% of the oral dose was not absorbed, the F value was approximately 29.4%, and the hepatic and gastrointestinal first-pass effects of mirodenafil were approximately 21.4% and 54.3% of the oral dose, respectively. The low F value of mirodenafil in rats was mainly due to considerable hepatic and gastrointestinal first-pass effects in rats. The equilibrium plasma-to-blood cell partition ratios of mirodenafil were independent of the initial blood mirodenafil concentrations of 1,10,µg/ml; the mean values were 1.08,1.21. The plasma binding values of mirodenafil to rat plasma was 87.8%. Copyright © 2009 John Wiley & Sons, Ltd. [source] Conformation analysis and molecular mobility of ethylene and tetrafluoroethylene copolymer using solid-state 19F MAS and 1H , 19F CP/MAS NMR spectroscopyMAGNETIC RESONANCE IN CHEMISTRY, Issue 7 2004Keitaro Aimi Abstract The changes in the conformation and molecular mobility accompanied by a phase transition in the crystalline domain were analyzed for ethylene (E) and tetrafluoroethylene (TFE) copolymer, ETFE, using variable-temperature (VT) solid-state 19F magic angle spinning (MAS) and 1H , 19F cross-polarization (CP)/MAS NMR spectroscopy. The shifts of the signals for fluorines in TFE units to higher frequency and the continuing decrease and increase in the T1,F values suggest that conformational exchange motions exist in the crystalline domain between 42 and 145 °C. Quantum chemical calculations of magnetic shielding constants showed that the high-frequency shift of TFE units should be induced by trans to gauche conformational changes at the CH2CF2 linkage in the E,TFE unit. Although the 19F signals of the crystalline domain are substantially overlapped with those of the amorphous domain at ambient probe temperature (68 °C), they were successfully distinguished by using the dipolar filter and spin-lock pulse sequences at 145 °C. The dipolar coupling constants for the crystalline domain, which can be estimated by fitting the dipolar oscillation behaviors in the 1H , 19F CP curve, showed a significant decrease with increasing temperature from 42 to 145 °C. This is due to the averaging of 1H19F dipolar interactions originating from the molecular motion in the crystalline domain. The increase in molecular mobility in the crystalline domain was clearly shown by VT T1,F and 1H , 19F CP measurements in the phase transition temperature range. Copyright © 2004 John Wiley & Sons, Ltd. [source] Inbreeding Coefficients for X-linked and Autosomal Genes in Consanguineous Marriages in Spanish Populations: The Case of Guipúzcoa (Basque Country)ANNALS OF HUMAN GENETICS, Issue 2 2009R. Calderón Summary Inbreeding patterns over the past two centuries have been studied more extensively in Spain and Italy than anywhere else in Europe. Consanguinity studies in mainland Spain have shown that populations settled along the Cantabrian cornice share inbreeding patterns that distinguish them from other populations further south. A visual representation of spatial variations of two key inbreeding variables is presented here for the first time via contour maps. This paper also analyzes time trends of mean inbreeding coefficients for X-linked (Fx) and autosomal genes (F) (1862,1995) together with variations in Fx/F ratios in Guipúzcoa, the most autochthonous Spanish Basque province. Because close cousin marriages are a mark of identity of the study population, we evaluated the contribution of uncle-niece/aunt-nephew (M12) and first cousin (M22) marriages to Fx and F values and compared the frequencies of M12 and M22 pedigree subtypes and their corresponding Fx/F ratios to those found in other Spanish populations. The mean Fx and F inbreeding levels in Guipúzcoa for the 134-year period analyzed were 1.51 × 10,3 and 1.04 × 10,3, respectively, and the Fx/F ratio was seen to be very stable over time. Our findings show that major similarities exist for close consanguineous marriage subtypes between Basque and non-Basque Spanish populations, despite significant geographic variability in terms of first cousin pedigrees. The distortion seems to be caused by Guipúzcoa. The Fx/F ratios for first cousins in Spanish populations were higher than expected (1.25), with values ranging from 1.34 to 1.48. The findings of the present study may be useful for advancing knowledge on the effects of the interaction between biology and culture and for exploring associations between mating patterns and the prevalence of certain diseases. [source] Mitochondrial phylogeography of the European sprat (Sprattus sprattus L., Clupeidae) reveals isolated climatically vulnerable populations in the Mediterranean Sea and range expansion in the northeast AtlanticMOLECULAR ECOLOGY, Issue 17 2008P. V. DEBES Abstract We examined the genetic structure of the European sprat (Sprattus sprattus) by means of a 530-bp sequence of the mitochondrial control region from 210 fish originating from seven sampling localities of its distributional range. Phylogeographical analysis of 128 haplotypes showed a phylogenetic separation into two major clades with the Strait of Sicily acting as a barrier to gene flow between them. While no population differentiation was observed based on analysis of molecular variance and net nucleotide differences between samples of the Baltic Sea, the North Sea and the Bay of Biscay nor between the Black Sea and the Bosporus, a strong population differentiation between these samples and two samples from the Mediterranean Sea was found. Further, the biggest genetic distance was observed within the Mediterranean Sea between the populations of the Gulf of Lyon and the Adriatic Sea, indicating genetic isolation of these regions. Low genetic diversities and star-like haplotype networks of both Mediterranean Sea populations point towards recent demographic expansion scenarios after low population size, which is further supported by negative FS values and unimodal mismatch distributions with a low mean. Along the northeast Atlantic coast, a northwards range expansion of a large and stable population can be assumed. The history of a diverse but differentiated Black Sea population remains unknown due to uncertainties in the palaeo-oceanography of this sea. Our genetic data did not confirm the presently used classification into subspecies but are only preliminary in the absence of nuclear genetic analyses. [source] Genetic diversity and phylogeographic analysis of Pinus leiophylla: a post-glacial range expansionJOURNAL OF BIOGEOGRAPHY, Issue 9 2009Abril Rodríguez-Banderas Abstract Aim, Mexico is a centre of diversity for species of the genus Pinus, most of which have restricted geographical distributions. An exception is Pinus leiophylla Schiede and Deppe, which is widely distributed throughout most of Mexico's mountainous regions. We attempt to reconstruct the phylogeographic history of this species, in order to determine if its current broad distribution is associated with major events of environmental change that occurred during the Quaternary. Location, Coniferous forests in Sierra Madre Occidental, Eje Volcánico Transversal and Sierra Montañosa del Norte de Oaxaca, Mexico. Methods, A total of 323 individuals of both P. leiophylla var. leiophylla and P. leiophylla var. chihuahuana sampled from 22 populations were screened for variation at six paternally inherited chloroplast DNA microsatellite markers (cpSSR). In addition to haplotypic diversity estimates and neutrality tests, the following clustering methods were employed: principal components analysis (PCA), analysis of molecular variance (AMOVA), spatial analysis of molecular variance (SAMOVA), haplotype network and a technique similar to Croizat's panbiogeographical method of individual and generalized tracks. Results, The combination of mutations at the six microsatellites yielded a total of 92 different haplotypes. The percentage of shared haplotypes between varieties (P. leiophylla var. leiophylla and P. leiophylla var. chihuahuana) was only 2.2%. The average haplotypic diversity for the species was H = 0.760. PCA and SAMOVA indicate the presence of four main genetic clusters. The estimated divergence time between the two most frequent haplotypes was between 75,000 and 110,000 years. Significantly large negative Fs values suggest that most of the sampled populations are currently expanding. Individual and generalized tracks identified three potential zones that may have harboured ancestral populations of P. leiophylla and from which the expansion of this species started, as well as two secondary contact zones between the two varieties. Main conclusions, The results indicate that one of the three potential areas hypothesized to have harboured ancestral populations of P. leiophylla may be related to the origin of P. leiophylla var. chihuahuana, while the other two may be related to the origin of P. leiophylla var. leiophylla. The current broad distribution of P. leiophylla is probably associated with its strong colonization ability. [source] A Novel Temperature-Compensated Microwave Dielectric (1,x)(Mg0.95Ni0.05)TiO3,xCa0.6La0.8/3TiO3 Ceramics SystemINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2009Chun-Hsu Shen The microstructure and microwave dielectric properties of a (1,x)(Mg0.95Ni0.05)TiO3,xCa0.6La0.8/3TiO3 ceramics system have been investigated. The system was prepared using a conventional solid-state ceramic route. In order to produce a temperature-stable material, Ca0.6La0.8/3TiO3 was added for a near-zero temperature coefficient (,f). With partial replacement of Mg2+ by Ni2+, the dielectric properties of the (1,x)(Mg0.95Ni0.05)TiO3,xCa0.6La0.8/3TiO3 ceramics can be promoted. The microwave dielectric properties are strongly correlated with the sintering temperature and the composition. An excellent Q × f value of 118,000 GHz can be obtained for the system with x=0.9 at 1325°C. For practical application, a dielectric constant (,r) of 24.61, a Q × f value of 102,000 GHz, and a temperature coefficient of resonant frequency (,f) of ,3.6 ppm/°C for 0.85(Mg0.95Ni0.05)TiO3,0.15Ca0.6La0.8/3TiO3 at 1325°C are proposed. A parallel-coupled line band-pass filter is designed and simulated using the proposed dielectric to study its performance. [source] Microstructure and Microwave Dielectric Properties of xCa(Al0.5Nb0.5)O3+(1,x)SrTiO3 Solid SolutionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Mingzhe Hu The crystal structure evolution and microwave (MW) dielectric properties of xCa(Al0.5Nb0.5)O3+(1,x)SrTiO3 (xCAN+(1,x)ST, 0,x,1.0, ) dielectric ceramics were investigated. X-ray diffraction patterns illustrated that a single perovskite solid solution could be formed between the two end members; however, minor amount of pyrochlore phase was also detected in the composition range of 0.5,x,0.9. With the increase of x value, the crystal structure gradually evolved from a simple Pm3m cubic to a monoclinic P21/n space group with the octahedral tilting and the B-site ordering structure transition subsequently developed. The MW dielectric properties of xCAN+(1,x)ST solid solutions were elaborately investigated and correlated to their crystal structures. The microscopic structure-related thermal parameters in the xCAN+(1,x)ST solid solution were analyzed in terms of the Claussius,Mossotti equation to reveal the original contributors in temperature coefficients. Temperature coefficient-compensated ceramic could be obtained in the xCAN+(1,x)ST system in the range of 0.5 Low-Loss Microwave Dielectrics in the Spinel-Structured (Mg1,xNix)Al2O4 Solid SolutionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010Cheng-Liang Huang Solid solutions of (Mg1,xNix)Al2O4 (x=0,1) have been prepared using the solid-state reaction method and their dielectric properties were measured at microwave frequencies. Formation of single-phase spinel-structured solid solutions was confirmed by X-ray diffraction analysis throughout the entire compositional range, and the measured lattice parameters varied linearly from 8.0810 Å at x=0 (MgAl2O4) to 8.0445 Å at x=1 (NiAl2O4) leading to a linear decrease in the unit cell volume from 527.71 to 520.59 Å3. The ionic polarizability obtained, however, increased with the increase of x to a maximum at x=0.25 and decreased thereafter. It shows only a small variance in the ,r with Ni substitution for Mg and a maximum ,r of 8.21 was achieved for (Mg0.75Ni0.25)Al2O4 in response to the highest ionic polarizability and relative density. However, the Q×f value can be significantly promoted up to a maximum value of 130 000 GHz (measured at 15.4 GHz) at x=0.25. In addition, substitution of Mg by Ni also helps to decline the ,f value from ,65 ppm/°C at x=0 to ,53.5 ppm/°C at x=0.25. [source] Microwave Dielectric Properties of A-Site Modified Ba(Co0.7Zn0.3)1/3Nb2/3O3 by La3+JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Jian Jiang Bian The sintering behavior, ordering state, and microwave dielectric properties of Ba1,xLa2x/3(Zn0.3Co0.7)1/3Nb2/3O3 Ceramics (0,x,0.06) were investigated in this paper. The X-ray diffraction (XRD) results show that all samples exhibit a single perovskite phase except for the sample with x,0.03. The sinterability is slightly improved by La doping. The long range order (LRO) degree on B-site is greatly increased with the increase of x value up to x=0.015 and then slightly decreased with the further increase of x due to the increasing amount of second phases. The dielectric constant at microwave frequency decreases slightly with the increase of x when x<0.015 and increases slightly with further increasing x for the samples sintered at 1375°C/10 h. The Q×f value increases with x up to x=0.015 and then decreases with further increase of x, which is consistent with the variation trend of LRO degree. The ,f value decreases slightly with the increase of x up to 0.006, then increases greatly with the further increase of x. An optimized dielectric properties of ,r=34, Q×f=63 159, GHz and ,f=5.21 ppm/°C were obtained for the x=0.01 sample sintered at 1425°C/10 h. [source] Microwave Dielectric Properties of Sintered Alumina Using Nano-Scaled Powders of , Alumina and TiO2JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2007Cheng-Liang Huang The microstructure and the microwave dielectric properties of nano-scaled , alumina (,-Al2O3) ceramics with various added amounts of nano-scaled TiO2 have been investigated. The sintering temperature of nano-scaled , alumina can be effectively lowered by increasing the TiO2 content. The Q×f values of nano-scaled , alumina could be tremendously boosted by adding an appropriate amount of TiO2. However, introducing excessive TiO2 into the alumina ceramics would instead lead to a decrease in the Q×f values. The phases of TiO2 and Al2TiO5 co-existed at 1350°C, and the maximum Q×f value appeared right after the eradication of TiO2 phase at 1400°C. Consequently, increasing the TiO2 content to 0.5 wt% yielded a Q×f value of 680 000 GHz (measured at 14 GHz) for nano-scaled , alumina prepared at 1400°C for duration of 4 h. In addition, a very low loss tangent (tan ,) of 2 × 10,5 was also obtained at 14 GHz. The ,f value is strongly correlated to the compositions and can be controlled through the existing phases. In fact, ,f could be adjusted to near zero by adding 8 wt% TiO2 to , alumina ceramics. A dielectric constant (,r) of 10.81, a high Q×f value of 338 000 GHz (measured at 14 GHz), and a temperature coefficient of resonant frequency (,f) of 1.3 ppm/°C were obtained for nano-scaled , alumina with 8 wt% TiO2 sintered at 1350°C for 4 h. Sintered ceramic samples were also characterized by X-ray diffraction and scanning electron microscopy. [source] Intramolecular structural relaxation in excited hetarylazole cationsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2005Valery V. Volchkov Abstract Neutral quinolyl-and pyridyl-substituted hetarylazoles and their protonated (ethylated) cations with anomalously high Stokes shifts were investigated. Fluorescence measurements at different temperatures and pressures confirmed the viscosity-dependent activation relaxation of the latter. Fluorescence kinetic analyses at various temperatures showed that in the range 293,77,K, the k,f values of cations increase 2,8-fold whereas those of neutral molecules change only 0.3,1.5-fold. The low-temperature time-resolved emission spectra of 1a, 1H+ and 5a were found to be consistent with the model: A,A*,B*, where A* is the local excited planar and B* is the relaxed twisted state of the molecule. Copyright © 2004 John Wiley & Sons, Ltd. [source] Explicit Calculation of the Friction Factor for Non-Newtonian Fluids Using Artificial Neural NetworksASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2005W. H. Shayya An explicit procedure based on artificial neural networks (ANN) was developed for calculating the friction factor (f) for Herschel-Bulkley fluids under laminar and turbulent flow conditions in closed pipes. The Regula-Falsi method was used as an iterative procedure to estimate the f values for a range of flow behavior indexes (n), Reynolds numbers (Re), and Hedstrom numbers (He). In developing the ANN model, the input parameters Re and He and the output parameter f were transformed using a logarithmic scale to the base 10, while the input parameter n was taken on a linear scale. An ANN configuration with 16 neurons in each of two hidden layers was found to be optimal. However, a simpler ANN model with eight neurons in one hidden layer also produced reasonably good predictions. These values were in close agreement with those obtained using the numerical technique. The developed ANN model may offer significant advantages when dealing with flow problems that involve repetitive calculations of the friction factor such as those encountered in the hydraulic analysis of viscous non-Newtonian fluids in pipe networks. [source]
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