Good Coefficient Of Variation Research Articles

Studies on Impact Resistance of Self-Compacting Concrete with mechanically treated Recycled Coarse Aggregate

Self-compacting concrete (SCC) is an extraordinary type of concrete that is extremely flowable and spreads into the formwork without the need of external vibration. In order to attain self-compatibility SCC obliges extensively surplus quantity of fine particles as compared to conventional concrete. Recycled Coarse Aggregate (RCA) obtained by crushing of old concrete is used in the investigational analysis. Nan-Su method is used to design the SCC mixes A and B (M35 and M45). The current experimental study aims to evaluate the impact energy of Recycled Coarse Aggregate (RCA) based self- compacting concrete by replacing with Natural Coarse Aggregate (NCA) (25%, 50%, 75%, and 100%) in unprocessed and processed states for various number of revolutions (500R, 1000R, 1500R, 2000R). Tests were carried out with a constant mass of hammer (16.38 kg). The impact energy determined for the Mixes A and B is compared with respect to replacement level and processing of RCA. The impact energy calculated is maximum for mix-A (1500 and 2000 revolutions) and mix-B (2000 revolutions) at 75% and 100% replacement of RCA respectively. From the experimental results of obtained Coefficient of Variation (CoV) with respect to processing of aggregate, in both the mixes it is observed that RCA in unprocessed state and processed state (1500R) has good Coefficient of Variation. Comparing the results of Coefficient of Variation with respect to replacement level of aggregate it has a very good CoV at 25% replacement level of RCA for both the mixes.

Accumulation and Determination of Phenylethanolamine A Residue in Hair of Swine and Sheep.

The present study proposed the use of liquid chromatography-tandem mass spectrometry to detect the novel β-agonist phenylethanolamine A (PEA) in incurred hair samples of swine and sheep and to assess its accumulation for residue monitoring. The method showed good percent recoveries ranging from 93.2% to 102% and good coefficient of variation at <15%. The experiment was conducted in swine (24 treated and 4 controls) and sheep (3 treated and 1 control). PEA concentration was determined in hair during the treatment. High residue concentrations were present in hair as early as Day 24 (14.8±3.6 and 25.8±7.6 ng/g) and Day 21 (23.4±6.6 ng/g) for swine and sheep; these residues persisted until withdrawal on Days 14 and 21. Results showed high PEA accumulation in hair, thereby indicating the use of hair as a matrix in the control of PEA abuse in farm animals.

Quantitative analysis of low-abundance serological proteins with peptide affinity-based enrichment and pseudo-multiple reaction monitoring by hybrid quadrupole time-of-flight mass spectrometry

Multiple reaction monitoring (MRM) is commonly used for the quantitative analysis of proteins during mass pectrometry (MS), and has excellent specificity and sensitivity for an analyte in a complex sample. In this study, a pseudo-MRM method for the quantitative analysis of low-abundance serological proteins was developed using hybrid quadrupole time-of-flight (hybrid Q-TOF) MS and peptide affinity-based enrichment. First, a pseudo-MRM-based analysis using hybrid Q-TOF MS was performed for synthetic peptides selected as targets and spiked into tryptic digests of human serum. By integrating multiple transition signals corresponding to fragment ions in the full scan MS/MS spectrum of a precursor ion of the target peptide, a pseudo-MRM MS analysis of the target peptide showed an increased signal-to-noise (S/N) ratio and sensitivity, as well as an improved reproducibility. The pseudo-MRM method was then used for the quantitative analysis of the tryptic peptides of two low-abundance serological proteins, tissue inhibitor of metalloproteinase 1 (TIMP1) and tissue-type protein tyrosine phosphatase kappa (PTPκ), which were prepared with peptide affinity-based enrichment from human serum. Finally, this method was used to detect femtomolar amounts of target peptides derived from TIMP1 and PTPκ, with good coefficients of variation (CV 2.7% and 9.8%, respectively), using a few microliters of human serum from colorectal cancer patients. The results suggest that pseudo-MRM using hybrid Q-TOF MS, combined with peptide affinity-based enrichment, could become a promising alternative for the quantitative analysis of low-abundance target proteins of interest in complex serum samples that avoids protein depletion.

Reproducibility of Neonate Ocular Circulation Measurements Using Laser Speckle Flowgraphy.

Measuring the ocular blood flow in neonates may clarify the relationships between eye diseases and ocular circulation abnormalities. However, no method for noninvasively measuring ocular circulation in neonates is established. We used laser speckle flowgraphy (LSFG) modified for neonates to measure their ocular circulation and investigated whether this method is reproducible. During their normal sleep, we studied 16 subjects (adjusted age of 34–48 weeks) whose blood flow could be measured three consecutive times. While the subjects slept in the supine position, three mean blur rate (MBR) values of the optic nerve head (ONH) were obtained: the MBR-A (mean of all values), MBR-V (vessel mean), and MBR-T (tissue mean), and nine blood flow pulse waveform parameters in the ONH were examined. We analyzed the coefficient of variation (COV) and the intraclass correlation coefficient (ICC) for each parameter. The COVs of the MBR values were all ≤10%. The ICCs of the MBR values were all >0.8. Good COVs were observed for the blowout score, blowout time, rising rate, falling rate, and acceleration time index. Although the measurement of ocular circulation in the neonates was difficult, our results exhibited reproducibility, suggesting that this method could be used in clinical research.

Confirmatory method for the determination of nitroimidazoles in milk by liquid chromatography - tandem mass spectrometry

Abstract A multiresidue method for the determination of seven nitroimidazoles and their hydroxy metabolites in milk was developed. Milk samples were extracted with acetonitrile and cleaned up on strong cation-exchange solid phase extraction cartridges. Evaporated to dryness first, the extracts obtained were then reconstituted in 0.1% formic acid and injected onto a liquid chromatography-tandem mass spectrometer (LC-MS/MS). The separation of analytes was achieved on gradient mode using a C18 column and a mobile phase consisting of 0.1% formic acid in acetonitrile and 0.1% formic acid in water. Multiple reaction monitoring mode was set for the MS/MS with positive electrospray ionisation. For quantification, the isotope dilution method was used with isotopically labeled analogues of the target analytes. The method was evaluated entirely in accordance with EU Commission Decision 2002/657/EC and all validation criteria were in the required ranges. The method can easily detect and confirm metronidazole, dimetridazole, ronidazole, ipronidazole, and their hydroxy metabolites below the recommended concentration level of 3 μg/kg. The decision limits and detection capabilities ranged from 0.11 μg/kg to 0.22 μg/kg and from 0.19 μg/kg to 0.37 μg/kg respectively. The overall recoveries were between 96.6% and 105.2% with a good coefficient of variation, less than 8.7% under within-laboratory reproducibility conditions.

Photometric Determination of Cu&lt;sup&gt;2+&lt;/sup&gt; Ion Using Octabromo-tetrakis(4-methylpyridyl)porphine

Octabromo-tetrakis(4-methylpyridyl)porphine (OBTMPyP), an octabromonated compound with 4 pyrole rings of tetrakis(4-methylpyridyl)porphine, selectively forms a complex with Cu2+ ions at pH 2.0. When 3.6×10(-5) mol/L OBTMPyP was added to the reaction mixture, the calibration curve showed good linearity for Cu2+ ions ranging from 0.01-2.2 µg (addition of 1.0 mL). A good coefficient of variation (Cu2+ ions=1.5 µg (addition of 1.0 mL), n=10, 0.8%) was obtained. The molar absorption coefficient (ε) based on Cu2+ ions was 8.5×10(4) L/mol•cm. This value was 6-fold greater than that determined with a clinical chemical analysis kit using the bathocuproine sulfonic acid method, which is a well-known method for spectrophotometric determination of the Cu2+ ion concentration. A deproteination method was successfully applied in the clinical analysis kit for determination of Cu2+ ion concentrations in control serum I, and the values determined using this method and the bathocuproine sulfonic acid method were almost the same.

Intra- and inter-session reliability of vertical jump performance in healthy middle-aged and older men and women

Despite its widespread use in performance assessment, the reliability of vertical jump in an ageing population has not been addressed properly. The aim of the present study was to assess intra- and inter-day reliability of countermovement jump in healthy middle-aged (55–65 years) and older (66–75 years) men and women. Eighty-two participants were recruited and asked to perform countermovement jumps on two different occasions interspersed by 4 weeks. The middle-aged groups exhibited excellent absolute reliability for flight height, jump height, peak force, peak power, peak force/body mass, and peak power/body mass, with coefficients of variation ranging from 2.9% to 7.2% in men and from 3.6% to 6.9% in women and moderate-to-high intraclass correlations (0.75 to 0.97 in men; 0.77 to 0.95 in women). The older groups displayed good coefficients of variation (4.2% to 10.8% in men and 3.4% to 9.5% in women), but the intraclass correlations were low-to-high (0.43 to 0.84 in men; 0.42 to 0.93 in women). Overall, intra-session reliability was higher than inter-session reliability. Peak power was by far the most consistent variable, whereas flight and jump height had the most marked variability. The minimum detectable change varied from 10.5% to 33%, depending on the variable examined, suggesting important implications for intervention studies.

UPLC-ESI-MS/MS analysis of Sudan dyes and Para Red in food

An analytical method for the simultaneous determination of Sudan dyes (Sudan Red G, Sudan I, Sudan II, Sudan III, Sudan Red 7B and Sudan IV) and Para Red in food by ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI-MS/MS) was developed. Samples were extracted with acetonitrile, and water added into the extract. The supernatant was analysed by UPLC-MS/MS after refrigeration and centrifugation. The sample was separated on an Acquity BEH C18 column, and detected by MS/MS with the multiple reaction monitoring mode. Matrix calibration was used for quantitative testing of the method. The linear matrix calibrations of Sudan dyes and Para Red were 2–50 and 10–250 ng g−1, respectively, and the regression coefficients were >0.9945. The recoveries were 83.4–112.3% with good coefficients of variation of 2.0–10.8%. The limits of detection were between 0.3 and 1.4 ng g−1 for the six Sudan dyes, and between 3.7 and 6.0 ng g−1 for Para Red. The limits of quantification were between 0.9 and 4.8 ng g−1 for the six Sudan dyes, and between 12.2 and 19.8 ng g−1 for Para Red.

Aspectos analíticos del analizador de gases Cobas ® b 221 (Roche Diagnostics)

Introduction and objectives The Cobas ® b 221 (Roche Diagnostics) is an automatic analyser for blood gas measurement in whole blood, with a wide range of parameters: pH, pO 2, pCO 2, co-oximetry, electrolytes, bilirubin, glucose, lactate and urea. The aim of this study is the assessment of imprecision and to investigate the agreement of the results between the Cobas ® b 221 and other analysers in order to introduce the Cobas ® b 221 as a blood gas analyser in the STAT section of the clinical laboratory. Material and methods For the intra- and inter-day imprecision study, three quality control levels provided by the manufacturer were evaluated. For the transferability study, 130 arterial blood samples and 100 venous blood samples were tested and a comparison between the results provided by the Cobas ® b 221 system and the ABL800 FLEX, Cobas 6000 and ADVIA 120 analysers was made. In the statistical study, parametric and non parametric tests were applied. For the regression analysis and for the evaluation of the concordance of results the Passing-Bablock method and the Bland-Altman method respectively were used. Results In the intra- and inter-day imprecision study, good coefficients of variation were obtained for all the studied parameters. Good correlation coefficients were observed in the correlation study (r>0.90, P<0.001). In the regression study, for most of the cases, a systematic and proportional error was found, which was due to the fact that the original slope and intercept did not include number one nor zero respectively. Moreover, differences between the statistically significant means ( P<0.001) were observed. From the statistical point of view, these data may indicate that the results would not be transferable. Nevertheless, low standard estimation errors (S y/x) and differences between the means lower than the clinically acceptable values were found together with minor systematic errors (mean of the differences between two methods) in the Bland-Altman plots as well as narrow and acceptable concordance limits. From the clinical point of view, these results indicate that the observed differences were not significant, except for glucose, for which, once the values measured with the Cobas ® b 221 analyser using the regression straight line are corrected, transferable results could be obtained. Conclusion Considering the results obtained together with other feasibility features of the Cobas ® b 221 analyser, we conclude that, in spite of the statistically significant differences between the results measured by the Cobas ® b 221 system and the comparison analysers, the differences found for the investigated parameters are not important from a clinical point of view and therefore, we consider that the Cobas ® b 221 blood gas analyser can be adapted to the daily routine of the STAT section in the clinical laboratory.

Multiresidue method for the determination of nitroimidazoles and their hydroxy-metabolites in poultry muscle, plasma and egg by isotope dilution liquid chromatography–mass spectrometry

A multiresidue analytical procedure for the determination of four nitroimidazoles (metronidazole, dimetridazole, ronidazole, ipronidazole) and their hydroxy-metabolites in poultry muscle, plasma and egg is presented. The procedure is based on ion-exchange solid phase extraction with acetonitrile as an extractant followed by liquid chromatography-mass spectrometry. The separation of analytes was performed on a C18 column using a mobile phase of 0.1% formic acid in acetonitrile and 0.1% formic acid in water with gradient elution. The electrospray ionization was used to obtain the protonated molecules [M+H](+) and two product ions were monitored for each compound. For the quantification stable isotope-labelled analogues of the analytes were used as internal standards. The whole procedure was evaluated according to EU Commission Decision 2002/657/EC requirements. Specificity, decision limit (CCalpha), detection capacity (CCbeta), recovery and precision were determined during validation process. The overall recoveries ranged between 93 and 103% with a good coefficient of variation, less than 14.0% under within-laboratory reproducibility conditions. CCalpha and CCbeta were 0.05-0.44 and 0.08-0.90microgkg(-1) depending on analyte and matrix.

An animal exposure system using ultrasonic nebulizer that generates well controlled aerosols from liquids.

Various aerosol generators have been developed for animal inhalation experiments and the performance tests of measuring instruments and respirators. It has been, however, difficult to generate aerosols from an aqueous solution or suspension keeping the concentration and particle size distribution constant for a long time. Resolving such difficulties, the present study developed an animal exposure system that generates well-controlled and stable aerosols from liquids. The exposure system consists of an aerosol generator using ultrasonic nebulizer, a mixing chamber and an exposure chamber. The validity of this system was confirmed in the generation of NiCl2 and TiO2 aerosol from solution and suspension, respectively. The concentration levels of NiCl2 aerosol were kept at 3.2 mg/m3 and 0.89 mg/m3 for 5 hours with good coefficients of variation (CVs) of 2.5% and 1.7%, respectively. For TiO2 aerosol, the concentration levels of 1.59 mg/m3 and 0.90 mg/m3 were kept for 5 hours with small CVs of 1.3% and 2.0%, respectively. This exposure system could be sufficiently used for inhalation experiments with even high toxic aerosols such as NiCl2 because a momentary high concentration possibly affects results and an extremely stable concentration is required.

A comparison of the neurothesiometer and biothesiometer for measuring vibration perception in diabetic patients

The Neurothesiometer is a new device designed to replace the Biothesiometer in screening for diabetic peripheral neuropathy by measuring vibration perception threshold (VPT). It was compared with the Biothesiometer in 85 diabetic patients, mean age 61 (range 21–82) years and mean duration of diabetes 12 (1–26) years, attending routine diabetes and foot screening clinics. VPT correlated with age and duration of diabetes ( r = 0.46 and r = 0.42, respectively P < 0.01), with both devices. The Biothesiometer VPT was 29.9 ± 15.2 V (mean ± S.D.) compared with 26.2 ± 13.4 V with the Neurothesiometer ( P = NS) and there was a close correlation between the two devices r = 0.93 P < 0.001. The within patient coefficient of variation was 8.6% for the Biothesiometer and 8.1% for the Neurothesiometer. The Neurothesiometer gives results that are in close agreement with the Biothesiometer and has a good coefficient of variation in routine clinical use. It is a self contained, battery operated device, which, although more expensive than its predecessor, is well suited to diabetes screening programmes and would be particularly useful to epidemiological surveys in the community.

Determination of total cholesterol in serum by flow injection analysis with immobilized enzymes

Several photometric and fluorimetric methods are proposed for the determination of cholesterol by use of enzymes immobilized on controlled-pore glass and the normal and stopped-flow injection modes, achieving linear ranges of the calibration curves between 26–776 μmol/l and 5–265 μmol/l with excellent regression coefficients and good coefficients of variation. The methods have been applied to the determination of this analyte in serum with excellent results.

Determination of DNA content by static cytofluorimetry in nuclei released from fixed plant tissue

Nuclei were extracted by crushing formaldehyde-fixed plant tissue, and smeared on slides with chick erythrocytes as internal standards, stained with the DNA-specific fluorochrome DAPI and measured by static cytofluorimetry. The ratios between the fluorescence of 2 C pea nuclei and of the internal standards corresponded to the ratio of the respective DNA contents reported in the literature; peaks with very good coefficient of variation (5–10%) were obtained and the mean fluorescence of 4 C nuclei was very close to twice that of the 2 C nuclei; percent distribution in G1 or G2 of nuclei from different tissues ofHelianthus andPisum were in full accordance with cytophotometric data in the literature. These results confirm the reliability of this method of DNA quantification, which is simpler and quicker in comparison with cytophotometric techniques.