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Coefficient R (coefficient + r)
Kinds of Coefficient R Selected AbstractsEvaluating the transport and removal of chromate using pyrite and biotite columnsHYDROLOGICAL PROCESSES, Issue 14 2007Chul-Min Chon Abstract To remove chromate from a wastewater, a porous permeable reactive barrier system (PRBS), using pyrite and biotite, was adapted. This study included bench-scale column experiments to evaluate the efficiency of the PRBS and investigate the reaction process. The total chromium concentration of the effluent from the biotite and pyrite columns reached the influent concentration of 0·10 mM after passing through more than 150 pore volumes (PVs) and 27 PVs respectively, and remained constant thereafter. The CrVI concentration in the effluent from the biotite column became constant at about 0·08 mM, accounting for approximately 80% of the influent concentration, after passing through 200 PVs. Moreover, in the pyrite column, the CrVI concentration remained at about 0·01 mM, 10% of the input level, after passing through 116 PVs. This shows that both columns maintained their levels of chromate reduction once the CrVI breakthrough curves (BTCs) had reached the steady state, though the steady-state output concentration of total chromium had reached the influent level. The variances of the iron concentration closely followed those of the chromium. The observed data for both columns were fitted to the predicted BTCs calculated by CXTFIT, a program for estimating the solute transport parameters from experimental data. The degradation coefficient µ of the total chromium BTCs for both columns was zero, suggesting the mechanisms for the removal of chromate limit the µ of the CrVI BTCs. The CrVI degradation of the pyrite column (6·60) was much greater than that of the biotite column (0·27). In addition, the CrVI retardation coefficient R of the pyrite column (253) was also larger than that of the biotite column (125). The R values for the total chromium BTCs from both columns were smaller than those of the CrVI BTC. Whereas the total chromium BTC for the pyrite column showed little retardation (1·5), the biotite column showed considerable retardation (80). The results for the 900 °C heat-treated biotite column were analogous to those of the control column (quartz sand). This suggests that the heat-treated biotite played no role in the retardation and removal of hexavalent chromium. The parameters of the heat-treated biotite were calculated to an R of 1·2 and µ of 0·01, and these values confirmed quantitatively that the heated biotite had little effect on the transport of CrVI. These solute transport parameters, calculated by CXTFIT from the data obtained from the column tests, can provide quantitative information for the evaluation of bench- or field-scale columns as a removal technology for CrVI in wastewater or contaminated groundwater. Copyright © 2006 John Wiley & Sons, Ltd. [source] Baric and temperature dependences of kinetic coefficients in p-Cd0.7Mn0.3GeAs2 at atmospheric and high pressuresPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2009A. Yu. Abstract The pressure dependences of the resistivity , (P) and Hall coefficient R,(P) have been measured for heavily doped Cd0.7Mn0.3GeAs2 at increasing and decreasing pressure at room temperature. To investigate temperature properties of conductivity in Cd0.7Mn0.3GeAs2, the temperature dependences , (T) and R,(T) have been defined in the temperature range 77,450 K at atmospheric pressure. The pioneering measurements of magnetoresistance ,,xx (H, P)/,0(P) in Cd0.7Mn0.3GeAs2 are presented. A hysteresis of magnetoresistive effect has been found when pressure rises and falls. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Degree of Desulphurization of a Limestone/Gypsum Wet FGD Spray Tower using Response Surface MethodologyCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2007Z. Zhao Abstract The degree of desulphurization was studied using response surface methodology (RSM), which enables effect examinations of parameters with a moderate number of experiments. All experiments were conducted in a lab-scale spray tower for limestone/gypsum wet flue gas desulphurization (FGD). The model flue gas was prepared from air and SO2 gas. The SO2 concentrations in the gas phase were determined by a multi-method analyzer. The degree of desulphurization correlated well with operating parameters, including pH, L/G, T, and v, with a determination coefficient R,Sq of 0.964. Effect tests indicate that L/G has the most significant influence on the degree of desulphurization. The interactions of L/G with pH, and with v, both play important roles. The result indicates that the evolutive response surface model is helpful to describe the degree of desulphurization of the limestone/gypsum wet FGD spray tower. [source] Solute movement through intact columns of cryoturbated Upper ChalkHYDROLOGICAL PROCESSES, Issue 13 2008M. Mahmood-ul-Hassan Abstract Cryoturbated Upper Chalk is a dichotomous porous medium wherein the intra-fragment porosity provides water storage and the inter-fragment porosity provides potential pathways for relatively rapid flow near saturation. Chloride tracer movement through 43 cm long and 45 cm diameter undisturbed chalk columns was studied at water application rates of 0·3, 1·0, and 1·5 cm h,1. Microscale heterogeneity in effluent was recorded using a grid collection system consisting of 98 funnel-shaped cells each 3·5 cm in diameter. The total porosity of the columns was 0·47 ± 0·02 m3 m,3, approximately 13% of pores were , 15 µm diameter, and the saturated hydraulic conductivity was 12·66 ± 1·31 m day,1. Although the column remained unsaturated during the leaching even at all application rates, proportionate flow through macropores increased as the application rate decreased. The number of dry cells (with 0 ml of effluent) increased as application rate decreased. Half of the leachate was collected from 15, 19 and 22 cells at 0·3, 1·0, 1·5 cm h,1 application rates respectively. Similar breakthrough curves (BTCs) were obtained at all three application rates when plotted as a function of cumulative drainage, but they were distinctly different when plotted as a function of time. The BTCs indicate that the columns have similar drainage requirement irrespective of application rates, as the rise to the maxima (C/Co) is almost similar. However, the time required to achieve that leaching requirement varies with application rates, and residence time was less in the case of a higher application rate. A two-region convection,dispersion model was used to describe the BTCs and fitted well (r2 = 0·97,0·99). There was a linear relationship between dispersion coefficient and pore water velocity (correlation coefficient r = 0·95). The results demonstrate the microscale heterogeneity of hydrodynamic properties in the Upper Chalk. Copyright © 2007 John Wiley & Sons, Ltd. [source] Rainfall interception in a lower montane forest in Ecuador: effects of canopy propertiesHYDROLOGICAL PROCESSES, Issue 7 2005Katrin Fleischbein Abstract Rainfall interception in forests is influenced by properties of the canopy that tend to vary over small distances. Our objectives were: (i) to determine the variables needed to model the interception loss of the canopy of a lower montane forest in south Ecuador, i.e. the storage capacity of the leaves S and of the trunks and branches St, and the fractions of direct throughfall p and stemflow pt; (ii) to assess the influence of canopy density and epiphyte coverage of trees on the interception of rainfall and subsequent evaporation losses. The study site was located on the eastern slope of the eastern cordillera in the south Ecuadorian Andes at 1900,2000 m above sea level. We monitored incident rainfall, throughfall, and stemflow between April 1998 and April 2001. In 2001, the leaf area index (LAI), inferred from light transmission, and epiphyte coverage was determined. The mean annual incident rainfall at three gauging stations ranged between 2319 and 2561 mm. The mean annual interception loss at five study transects in the forest varied between 591 and 1321 mm, i.e. between 25 and 52% of the incident rainfall. Mean S was estimated at 1·91 mm for relatively dry weeks with a regression model and at 2·46 mm for all weeks with the analytical Gash model; the respective estimates of mean St were 0·04 mm and 0·09 mm, of mean p were 0·42 and 0·63, and of mean pt were 0·003 and 0·012. The LAI ranged from 5·19 to 9·32. Epiphytes, mostly bryophytes, covered up to 80% of the trunk and branch surfaces. The fraction of direct throughfall p and the LAI correlated significantly with interception loss (Pearson's correlation coefficient r = ,0·77 and 0·35 respectively, n = 40). Bryophyte and lichen coverage tended to decrease St and vascular epiphytes tended to increase it, although there was no significant correlation between epiphyte coverage and interception loss. Our results demonstrate that canopy density influences interception loss but only explains part of the total variation in interception loss. Copyright © 2004 John Wiley & Sons, Ltd. [source] Ulcerative colitis: Correlation of the Rachmilewitz endoscopic activity index with fecal calprotectin, clinical activity, C-reactive protein, and blood leukocytesINFLAMMATORY BOWEL DISEASES, Issue 12 2009Alain M. Schoepfer MD Abstract Background: The accuracy of noninvasive markers for the detection of endoscopically active ulcerative colitis (UC) according the Rachmilewitz Score is so far unknown. The aim was to evaluate the correlation between endoscopic disease activity and fecal calprotectin, Clinical Activity Index, C-reactive protein (CRP), and blood leukocytes. Methods: UC patients undergoing colonoscopy were prospectively enrolled and scored independently according the endoscopic and clinical part of the Rachmilewitz Index. Patients and controls provided fecal and blood samples for measuring calprotectin, CRP, and leukocytes. Results: Values in UC patients (n = 134) compared to controls (n = 48): calprotectin: 396 ± 351 versus 18.1 ± 5 ,g/g, CRP 16 ± 13 versus 3 ± 2 mg/L, blood leukocytes 9.9 ± 3.5 versus 5.4 ± 1.9 g/L (all P < 0.001). Endoscopic disease activity correlated closest with calprotectin (Spearman's rank correlation coefficient r = 0.834), followed by Clinical Activity Index (r = 0.672), CRP (r = 0.503), and leukocytes (r = 0.461). Calprotectin levels were significantly lower in UC patients with inactive disease (endoscopic score 0,3, calprotectin 42 ± 38 ,g/g), compared to patients with mild (score 4,6, calprotectin 210 ± 121 ,g/g, P < 0.001), moderate (score 7,9, calprotectin 392 ± 246 ,g/g, P = 0.002), and severe disease (score 10,12, calprotectin 730 ± 291 ,g/g, P < 0.001). The overall accuracy for the detection of endoscopically active disease (score ,4) was 89% for calprotectin, 73% for Clinical Activity Index, 62% for elevated CRP, and 60% for leukocytosis. Conclusions: Fecal calprotectin correlated closest with endoscopic disease activity, followed by Clinical Activity Index, CRP, and blood leukocytes. Furthermore, fecal calprotectin was the only marker that reliably discriminated inactive from mild, moderate, and highly active disease, which emphasizes its usefulness for activity monitoring. Inflamm Bowel Dis 2009 [source] The power of children over adults when obtaining sweet snacksINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 2 2003B. P. Roberts Summary. Background. There is evidence to suggest that the family is becoming a more democratic unit and that children are spending more on sweet snack items than ever before. A study was thus undertaken to investigate the influence of children on parental decision-making in relation to the use of sugary snacks. Methods. A cross sectional interview study; children aged 7,8 years from 20 inner-city Manchester primary schools were asked about their sweet eating, their pocket money and their perceived levels of influence or autonomy within the household. The parents of these children were also asked to fill in a questionnaire that mirrored the children's questions. Results. There was a moderate but significant correlation between the opinion of the parents and that of the children on the extent of influence (Pearson coefficient r = 0·25, P = 0·001). When the adults (n = 181) were split into age groups, , 29 years (n = 33), 30,35 years (n = 61) and , 36 years (n = 87), the study showed that the older the adult, the less the child seemed to get his or her own way. Spearman's rho = 0·16, P = 0·03 (children's view) and rho = 0·17, P = 0·02 (adult's view). The dominant factors were related to money in the children's opinion, although the adults' data suggested that older mothers (, 36 years) may be trying to limit their children's access to sweet snacks. Conclusions. Adults' efforts to limit their children's intake of sweet snacks and drinks are being undermined by earlier and earlier influences in the child's life and by access to money, which allows the child to out-manoeuvre his or her parents. This is compounded by the provision of additional income, mostly from grandparents. [source] Simultaneous determination of simvastatin and simvastatin acid in human plasma by LC-MS/MS without polarity switch: Application to a bioequivalence studyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2008Bhavin N. Patel Abstract A simple, specific and sensitive LC-MS/MS assay for simultaneous determination of simvastatin (SV) and its active ,-hydroxy acid metabolite, simvastatin acid (SVA) in human plasma was developed using a statin analog as internal standard (IS). The method was validated over a dynamic linear range of 0.20,100.00 ng/mL for SV and 0.10,50.00 ng/mL for SVA with correlation coefficient r , 0.9987 and 0.9989, respectively. The analytes and IS were extracted from 500 ,L aliquots of human plasma via liquid-liquid extraction using methyl tert -butyl ether and separated through an Aquasil C18 column (100 mm×2.1 mm, 5 ,m). Detection of analytes and IS was done by MS/MS with a turbo ion spray interface operating in positive ion and selective reaction monitoring acquisition mode. The total chromatographic run time was 3.0 min. Flash freezing of the aqueous phase was an added advantage during liquid-liquid extraction, which considerably reduced time and labour. The method was extensively validated for its accuracy, precision, recovery, stability studies and matrix effect. The method was successfully used for bioequivalence study of 40 mg SV tablet formulation in 12 human subjects under fasting condition. [source] Liver transplantation for progressive familial intrahepatic cholestasis: Clinical and histopathological findings, outcome and impact on growthPEDIATRIC TRANSPLANTATION, Issue 6 2007Sema Aydogdu Abstract:, In this study, we analyze the demographic features, clinical and histopathological findings in patients who underwent liver transplantation for progressive familial intrahepatic cholestasis. We also analyze outcome and impact of liver transplantation on growth and bone mineral content. Most of the patients were presented with jaundice mainly beginning within the first six months. At the time of initial admission; eight patients had short stature (height SD score <2), and four patients had weight SD score <2. Liver transplantation were performed at the age of 43.2 ± 27 months (range 9 to 96 mfonths), 6.5 ± 3.5 months later after the first admission. Infection, surgical complications and osmotic diarrhea associated with severe metabolic acidosis were noted in 41.4%, 16.6% and 33.3%, respectively. One patient developed posttransplant lymphoproliferative disorder. Overall; 1 year graft and patient survival was 69.2% and 75%, respectively. At the end of the 1st year only 2 patients had height SD score <2. Linear regression of height gain against increase in total body BMD measured at the time of transplantation and 1 year after liver transplantation gave a coefficient r = 0.588 (p = 0.074). No correlation was found between the height gain and age and PELD score at time of transplantation, and no difference was noted between the sexes and donor type. Liver transplantation is effective treatment modality with good outcome and little morbidity, and increases the growth acceleration in patients with PFIC associated with cirrhosis. [source] Determination of levetiracetam in human plasma by liquid chromatography/electrospray tandem mass spectrometry and its application to bioequivalence studiesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2006Deepak S. Jain The first liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the determination of levetiracetam, an antiepileptic drug, in human plasma is described. The plasma filtrate obtained after solid-phase extraction (SPE), using a polymer-based, hydrophilic-lipophilic balanced (HLB) cartridge, was submitted directly to a short column LC/MS/MS assay. There was no significant matrix effect on the analysis. For validation of the method, the recovery of the free analytes was compared to that from an optimized extraction method, and the analyte stability was examined under conditions mimicking sample storage, handling, and analytical procedures. The extraction procedure yielded extremely clean extracts with a recovery of 79.95% and 89.02% for levetiracetam and the internal standard (IS), respectively. The intra-assay and inter-assay precision for the samples at the lower limit of quantitation (LLOQ) were 6.33 and 6.82%, respectively. The calibration curves were linear for the dynamic range of 0.5 to 50,µg/mL with a correlation coefficient r,,,0.9971. The intra-assay accuracy at LLOQ, LQC, MQC, and HQC levels ranged from 81.60 to 95.40, 93.00 to 103.47, 95.97 to 104.09, and 91.15 to 95.18%, respectively, while the inter-assay accuracy at LLOQ, LQC, MQC and HQC levels varied from 80.20 to 95.40, 88.53 to 107.53, 95.97 to 108.45, and 91.15 to 112.70%, respectively. The method is rugged and fast with a total instrumental run time of 2,min. The method was successfully applied for bioequivalence studies in human subject samples after oral administration of 1000,mg immediate release (IR) formulations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Immunohistochemical expression of tumor antigens MAGE-A1, MAGE-A3/4, and NY-ESO-1 in cancerous and benign prostatic tissueTHE PROSTATE, Issue 1 2006Tvrtko Hudolin Abstract OBJECTIVE To investigate immunohistochemical expression of MAGE-A and NY-ESO-1/LAGE-1, cancer testis antigens in prostate tissues showing evidence of malignant transformation or benign hyperplasia. METHODS 112 prostate samples from patients undergoing surgery at the Urology Clinic at the Zagreb Clinical Hospital Center from 1995 to 2003 were investigated in this study. Of these, 92 carcinoma samples were obtained by radical prostatectomy, and 20 benign prostatic hyperplasia samples by transvesical prostatectomy. Three monoclonal antibodies were used for immunohistochemical staining: 77B for MAGE-A1, 57B for multi-MAGE-A and D8.38 for NY-ESO-1 expression. RESULTS Expression of MAGE-A1 was observed in 10.8% of carcinoma samples, whereas multi-MAGE-A and NY-ESO-1/LAGE-1 stained 85.9% and 84.8% of samples. Immunohistochemical staining was only detectable in the cytoplasm. A significant heterogeneity could be observed within a same tissue sample where areas with strong positivities coexisted with cancer testis antigens negative areas. Interestingly, a majority of 57B positive cases were also found to be D8.38 positive (correlation coefficient r,=,0.727 (P,<,0.01)). Cancer testis antigens expression was neither significantly correlated with PSA values nor with Gleason score. In benign prostatic hyperplasia tissues MAGE-A1 expression was detected in 5%, while 57B and D8.38 staining was observed in 15% samples, and in all cases percentages of positive cells were always <10%. CONCLUSION Our data underline the peculiar relevance of cancer testis antigens expression in prostate cancers, with potential implications regarding both diagnosis and therapy. © 2005 Wiley-Liss, Inc. [source] Vibration Analysis on Incubating Eggs and Its Relation to Embryonic DevelopmentBIOTECHNOLOGY PROGRESS, Issue 3 2003Bart J. Kemps Coucke (1998) was the first to use acoustic resonance analysis to monitor embryo development in chicken eggs. He remarked that at around 100 hours of incubation, the course of the resonant frequency and damping changed abruptly in the case of fertile eggs. He also showed that these changes were related to a physiologic event during early embryonic development. The objective of our study is to monitor the course of the vibration parameters during the early incubation of chicken eggs and to relate these changes to egg and embryo characteristics. A total of 72 Hybro eggs were incubated vertically in a small incubator at standard conditions. Several egg parameters were measured before incubation. During the early stages of incubation the vibration behavior of these eggs was monitored. The time at which the damping of the vibration suddenly changed, the diameter of the eggs and their interaction were found to be significant explanatory variables in order to predict hatching time. A correlation coefficient r of 0.72 was obtained. [source] Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass SpectrometryCHINESE JOURNAL OF CHEMISTRY, Issue 9 2007Yan Liu Abstract A determination method has been optimized and validated for the simultaneous analysis of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DC) in honey. Tetracyclines (TCs) were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction (SPE), while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile, and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 µg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% (n=18). Detection limits of 5, 5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey(2,50 ng/g) was realized by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r>0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey. [source] Spatially-localized correlation of dGEMRIC-measured GAG distribution and mechanical stiffness in the human tibial plateauJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2005Joseph T. Samosky Abstract The concentration of glycosaminoglycan (GAG) in articular cartilage is known to be an important determinant of tissue mechanical properties based on numerous studies relating bulk GAG and mechanical properties. To date limited information exists regarding the relationship between GAG and mechanical properties on a spatially-localized basis in intact samples of native tissue. This relation can now be explored by using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC,a recently available non-destructive magnetic resonance imaging method for measuring glycosaminoglycan concentration) combined with non-destructive mechanical indentation testing. In this study, three tibial plateaus from patients undergoing total knee arthroplasty were imaged by dGEMRIC. At 33,44 test locations for each tibial plateau, the load response to focal indentation was measured as an index of cartilage stiffness. Overall, a high correlation was found between the dGEMRIC index (T) and local stiffness (Pearson correlation coefficients r = 0.90, 0.64, 0.81; p < 0.0001) when the GAG at each test location was averaged over a depth of tissue comparable to that affected by the indentation. When GAG was averaged over larger depths, the correlations were generally lower. In addition, the correlations improved when the central and peripheral (submeniscal) areas of the tibial plateau were analyzed separately, suggesting that a factor other than GAG concentration is also contributing to indentation stiffness. The results demonstrate the importance of MRI in yielding spatial localization of GAG concentration in the evaluation of cartilage mechanical properties when heterogeneous samples are involved and suggest the possibility that the evaluation of mechanical properties may be improved further by adding other MRI parameters sensitive to the collagen component of cartilage. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] | ||||||||||||||||