Gave Correlation Coefficients Research Articles

Genotypic response of chickpea (Cicer arietinum L.) cultivars to drought stress implemented at pre- and post-anthesis stages and its relations with nutrient uptake and efficiency

Uptake of mineral nutrients in chickpea cultivars might be an important response in drought tolerance. An experiment under controlled conditions was carried out to study the genotypic response of 11 chickpea (Cicer arietinum L.) cultivars to drought and its relations with N, P, K, Ca, Mg, Fe, Zn, Mn and B uptake and uptake efficiency. Plants were grown either optimal or drought stress implemented at pre- (early drought stress, EDS) and post-anthesis (late drought stress, LDS) stages. Growth reduction of the cultivars as a response to drought significantly differed. The results of the study indicated that EDS had less detrimental effects on growth and nutrient uptake than LDS conditions. In general, drought tolerant chickpea cultivars accumulated more N, P, K, Ca, Zn, Mn and B in both drought stress treatments except for Zn and Mn uptake in LDS treatment. The total nutrient uptake efficiency of the cultivars were also very significantly correlated with the growth reduction ration (GR) both in EDS and LDS treatments giving correlation coefficients (r) of –7859 and –0.7678, p < 0.01, respectively.

Quantitative Estimation of Reservoir Sedimentation from Three Typhoon Events

Study of soil erosion in the reservoir watershed, the main source of reservoir sedimentation that affects the reservoir's lifespan and capacity, is of vital importance for watershed management. Due mainly to the lack of data, empirical formulas are commonly used to estimate reservoir sedimentation. However, these estimations are far from accurate. Field measurements data of discharge and suspended sediment were collected during three typhoon events in Shihmen Reservoir watershed, Taiwan. Temporal variations of water surface elevation, discharge, and concentration of suspended sediment were measured. A numerical model, Hydrological Simulation Program Fortran HSPF, developed by the USEPA was adopted to simulate the sediment yield. However, as calibration and verification data are not always available and the parameter-calibration process is complicated and tedious for novice users of the model, an artificial neural network ANN model was proposed. Significant amount of the synthetic data from the calibrated HSPF model were first generated to train the ANN model, which in turn was used to estimate the sediment yield. Comparisons of the sediment yield using both the HSPF and ANN model give correlation coefficients of 0.96 for training and 0.93 for validation. Without the complicated parameter calibration process, the ANN model was faster and easier to use than the HSPF model.

Effect of the Location of the Inlet and Outlet Structures on Short-Circuiting: Experimental Investigation

The location of the inlet and outlet structures in a treatment plant (e.g., waste stabilization pond) may affect its hydraulic efficiency by increasing short-circuiting. Therefore, in this paper, the effect of the location of inlet and outlet structures was investigated in three laboratory channels of different lengths. Nine different combinations of inlet and outlet locations were considered for each channel under varying rates of flow. Results showed that the placement of the inlet and outlet structures close to the surface and the bottom of the pond, respectively, gave the minimum value of short-circuiting. This location was, therefore, judged to be the optimum among the nine combinations considered. The short-circuiting index was found to increase both with the dispersion number and the actual flow velocity, giving correlation coefficients of 0.3186 to 0.9258 and 0.8057 to 0.9972, respectively. Although minimization of short-circuiting will result in higher hydraulic efficiency, it may not necessarily result in higher effluent quality unless the temporal and vertical fluctuations of the water column are also considered.

An improved liquid chromatographic method with electrochemical detection for direct determination of serotonin in microdialysates from Caudate-putamen and pineal gland regions of rat brain

A liquid chromatography method coupled with electrochemical detection has been developed for the direct measurement 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in brain microdialysates. The separation conditions have been optimized to detect only the 5-HT and 5-HIAA in dialysates and elute the other monoamines and their metabolites in the void. Linear regression analysis of chromatographic peak area as a function of concentration in the range 5–1000 pg/mL gave correlation coefficients over 0.995. Sample stability and an assay validation for precision and accuracy were also performed. The limit of detection (S/N = 3) for 5-HT was 12 femtomol/mL. The method has been applied to simultaneously measure extracellular 5-HT and 5-HIAA in brain microdialysates from the pineal gland and caudate-putamen of awake and freely-moving rats under basal conditions.

Image analysis of skin scaling using D‐Squame® samplers: comparison with clinical scoring and use for assessing moisturizer efficacy

The severity of scaling disorders can be evaluated objectively using the D-Squame technique coupled with image analysis. The parameters of scaling derived using this approach need to be clinically relevant and should have greater discrimination than visual grading. Improvements to an existing method that fulfil these requirements are presented. Three scaling parameters were calculated using image analysis of digitized video-captured images of obliquely lit D-Squame samples. These parameters were compared to clinical scores of scaling made by five observers from photographs of the same areas sampled with D-Squame. In addition, two clinical studies were carried out to assess moisturizer effects on different degrees of xerosis, and to compare two different moisturizer preparations. The three scaling parameters gave correlation coefficients, r, between 0.6 and 0.75 when compared with global clinical scores of scaling. Significant reductions in all parameters were observed with 2 weeks of moisturizer use on lower leg skin with marked xerosis compared to an untreated control. The same moisturizer had a similar effect on milder xerosis of the forearm, and showed a greater decrease than a moisturizer with lower glycerol content. Increases in skin hydration, as measured with a corneometer, were also seen in both clinical studies, and corresponded well with D-Squame results. Differences in the degrees of scaling between these two anatomical sites were also detected with this technique. In a previous publication, the same technique was shown to be repeatable and reproducible; in the current article its correlation with clinical observations of scaling or flaking skin has been demonstrated.

Physical model for the downhole orbital vibrator (DOV) - II. Rotary correlation wavelets and time-lapse seismics

SUMMARY The downhole orbital vibrator (DOV) acts as a rotating acoustic point force coupled to the borehole fluid. Operated as a Vibroseis source modulated over rotational frequencies 50- 350 Hz, the DOV can generate crosswell seismic signals at well separations up to 800 m in oilfield sediments. Source-wavelet stability and crosswell seismic traveltime resolution are estimated from an ensemble of 13 000 wavelets recorded at a crosswell seismic facility with 300 m source-sensor separation. DOV auto-correlation source wavelets Si cross-correlated against the ensemble mean wavelet Smn give correlation coefficients γ i = SiS mn having mean γ mn ≈ 99.97 per cent and standard deviation γ rms ≈ 0.03 per cent. S wavelets give observed traveltimes τ i with normalized standard deviation �τ rms/τ mn ≈ 0.03 per cent. This level of seismic monitoring source stability and crosswell traveltime resolution offers considerable promise for accurate, cost-effective time-lapse seismic imaging of active geofluid reservoirs. Application of stable DOV waveform production to time-lapse seismic imaging is, how- ever, affected by the dual-wavelet nature of rotary motion cross-correlations. In general, DOV cross-correlation signals mix time-symmetric (even) wavelets χ cc(t) ∼ cos(ω(t)t) � cos(ω(t)t) ∼ χ cc(−t) and time-antisymmetric (odd) wavelets χ cs(t) ∼ cos(ω(t)t) � sin(ω(t)t) ∼ − χ cs(−t), wheredenotes correlation, ω(t) describes the modulation of rotational frequency, and time-reversal t ↔− t equates to interchanging clockwise/counter-clockwise (cw/ccw )D OV rotations. Cross-correlating sensor motion along source-sensor axis x with source motion along axis g mixes wavelet symmetries as χ g(t) ∼ cosφχ cc(t) + sinφχ cs(t) where cos φ = g · x and angle φ orients the DOV relative to the source-sensor axis. DOV orientation uncertainty �φ affects the sensor wavelet apparent traveltime as �τ ≈ 1.3(�φ/2π )T min, T min the period of peak modulation frequency. Since source orientation un- certainty can generate apparent traveltime uncertainty as large as 1-2 ms, time-lapse seismics cannot effectively ignore DOV orientation. Traveltime resolution can be improved to order 0.1 ms without knowing DOV orientation if traveltimes are computed using even/odd wavelets composed by summing/differencing cw/ccw wavelets. Prospects for time-lapse resolution im- prove if observers can orient the DOV. A DOV equipped with a collar of rotation-phase point detectors surrounding the rotating mass permits observer selection of the monitor sensor, hence controlling effective source orientation. DOV orientation can be guided by an on-board biaxial tiltmeter (for borehole tilt δ along an axis making angle φ with DOV sensor orientation, biaxial tilts T 1 and T 2 fix φ as T 1 =− cos φtan δ and T 2 = sin φtan δ). Numerical simulation of full-sensitivity time-lapse reservoir monitoring suggests it is feasible to resolve migrating oil/water substitution volumes of characteristic dimension 20 m with crosswell transmission data over ≈600-800 m offsets, or in backscatter data at offsets ≈100-200 m using a DOV and sensor array operating in a single well.

A simplified flow cytometry method of CD4 and CD8 cell counting based on thermoresistant reagents: Implications for large scale monitoring of HIV‐infected patients in resource‐limited settings

To validate a simplified flow cytometry assay for CD4 and CD8 T cell counting based on monoclonal antibodies which are made resistant to high temperatures (simplified thermoresistant assay (STRA)). The STRA employs FITC-conjugated anti-CD4 and anti-CD8 monoclonal antibodies, predispensed into test tubes and chemically treated to be resistant to high temperatures. Five correlation studies were performed in three different laboratories on a total of 560 blood samples from HIV-1 infected patients. Each study correlated the STRA with either double or single platform assays currently available. Accelerated stability tests on the FITC-conjugated monoclonal antibodies were performed to assess the resistance of the STRA to high temperatures. Comparison of STRA with both single platform and double platform assays gave correlation coefficients ranging 0.957-0.987 for CD4+ T cells and 0.946-0.968 for CD8+ T cells. In all correlation studies there was a perfect data overlapping in the low-pathological interval of CD4+ T cells (0-400 cells/ml). The FITC-conjugated CD4 and CD8 monoclonal antibodies maintained intact binding activity and fluorescence brightness after storage for 4 weeks at 45 degrees C and can be stored for up to 8 years in regular conditions (+4 degrees C). The STRA correlates well with both single-platform and double-platform flow-cytometry assays currently used to assess CD4+ T cells. The test procedure is simple, rapid, and easy to perform. The reagents can be stored under unfavorable environmental conditions for long period of time. These features should facilitate access to flow cytometry testing in resource-poor settings.

Optical system for measurement of internal pear quality using near-infrared spectroscopy

An optical system based on Fourier transform near-infrared spectroscopy for nondestructive measurement of internal quality in intact fruit was developed. This system consisted of a light source, interferometer, fiber optical sensor, InGaAs detector, data collection card, and fruit holder. Quantification tests for sugar content (SC) and titratable acidity (TA) of 248 pear samples were carried out by using the multivariate calibration technique of partial least squares (PLS). The calibration model for SC and TA gave correlation coefficients of determination of 0.867 and 0.793, standard errors of calibration of 0.256 and 0.020, and standard errors of prediction of 0.320 and 0.019, respectively. Experimental results show that this optical system could be directly applied to fast quantification analysis for internal quality of fruits.

Using optical NIR sensor for on-line virgin olive oils characterization

Near-infrared transmittance spectroscopy was applied to on-line control quality and characterization of virgin olive oils. The transmittance spectrum (log 1/ T) was obtained through dispersal equipment, scanning the samples between 750 and 2500. A 1 mm optical path length flow cell and holding 120 μl was employed. Calibration models for: acidity value (AV), bitter taste (k225) and fatty acid composition (FAME), were previously developed in the laboratory using partial least squares (PLS) regression. A total of 190 virgin olive oil samples, gathered during the usual harvesting time of three olive crop seasons, were used. The validation set gave correlation coefficients and standard error of prediction of 0.999 and 0.35, 0.936 and 0.058, 0.998 and 0.604, 0.992 and 0.674% for AV, k225, fatty acid oleic and fatty acid linoleic, respectively. These PLS models, prior to a slope/bias correction, were used to monitor on-line values of these parameters during the processing of virgin olive oils in real olive mills. Samples of oils were obtained for chemical analysis. Application of NIR transmittance spectroscopy on-line to virgin olive oil production line, has allowed to detect, at real-time, the changes produced in the characteristics of the oils during their production. The results indicate similarity between information both NIR and reference laboratory methods.

High-performance liquid chromatographic and spectrofluorometric determination of α-tocopherol in a natural plant: Ferula hermonis (Zalooh root)

A high-performance liquid chromatographic (HPLC) method for the determination of α-tocopherol in a natural plant ( Ferula hermonis–Zalooh roots) is reported. The method includes saponification of samples and extraction of α-tocopherol with a mixture of acetonitrile and methanol (1:1 v/v). However, the presence of α-tocopherol in Zalooh is confirmed with HPLC-UV and fluorescence detection. A spectrofluorometric and the internal addition standard methods are also used to quantify the α-tocopherol in the plant. An internal standard method is based on a known concentration of α-tocopherol that is added in every sample that is analyzed. Alpha-tocopherol levels as determined in samples by HPLC with UV and fluorescence detection ( ≈ 5 ± 0.5 mg / g ) did not differ significantly from the levels determined by Shimadzu spectrofluorometer ( 4.9 ± 0.5 mg / g ). However, the amount of tocopherol determined by both techniques in Zalooh roots was relatively very high. Standards were checked for linearity giving correlation coefficients that were higher than 0.99 in the concentration range of 1 and 6 μmol L −1.

Detection and quantitation of curcumin in mouse lung cell cultures by matrix-assisted laser desorption ionization time of flight mass spectrometry

A method to detect and quantify curcumin and two curcuminoid metabolites in biological matrices, including mouse serum and mouse lung cell cultures, was developed. Standard curves between 0.04 and 10.00 nmol curcumin were prepared in serum, giving correlation coefficients of 0.94–0.99. Alcoholic extraction, concentration, and addition of dilute hydrochloric acid to stabilize the curcumin were essential to the reproducibility of the protocol. Untreated and curcumin-treated mouse lung fibrotic and nonfibrotic cell cultures were analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry utilizing this method. Curcumin uptake was calculated to be 7.0–11.6% for the saline-treated cells and 7.4–11.9% for the bleomycin-treated cultures. Curcumin was not detected in untreated cells. Two additional peaks ( m/ z = 399 and 429) were observed in the curcumin-treated cells. These may be curcumin-derived products resulting from HCl treatment of the tissue samples.

Association Between the Rates of Multiple Maternities

We analyze the association between the rates of multiple maternities. Correlation analysis is suitable if there are at least monotonic relationships between the variables. A decreasing tendency can be observed in the rates of multiple maternities in Sweden and in its 25 counties for the period 1751-1960 and the effect of external variables can be assumed to be monotonic. After 1960, the rates of multiple maternities show marked increases, mainly caused by ovulation stimulants and the introduction of other artificial reproduction techniques. We transformed the triplet and quadruplet rates according to Hellin's law in order to obtain rates on the same scale as the twinning rate. The time trends for the multiple maternities in Sweden as a whole were quite similar. The regional differences in the twinning rates could not be satisfactorily explained by maternal age. Alternative attempts to eliminate the effect of other time-dependent factors were to study partial correlation coefficients when the time was kept fixed and the correlation coefficients based on cross-sectional regional data. Both the ordinary and the partial correlation coefficients showed strong regional variation. Cross-sectional analyses gave correlation coefficients similar to the partial correlation coefficients for Sweden as a whole. The variations in the correlation coefficients between the twinning and the triplet rates seem to be caused by other time-dependent factors and the effects of these factors show strong regional variation. After elimination of such factors, the correlation between the twinning and the triplet rates is moderate.

Comparative evaluation of palm oil color measurement using a prototype palm oil colorimeter

AbstractThe color of refined palm oil and palm oil products is conventionally measured using the manually operated Lovibond® Tintometer. In the present study, one manual/visual and three automatic colorimeters for the measurement of vegetable oil color were used for color measurements of refined palm oil. All colorimeters used were commercially available instruments except for an automatic palm oil colorimeter developed specifically for the measurement of palm oil color. The color values obtained from all four instruments were compared using the visually obtained readings as reference values. Results showed that all three automatic instruments gave correlation coefficients of greater than 0.9300 for red color measurements. In addition, the Student t‐test showed no difference between the analysis of red color using the visual method and the palm oil colorimeter. This investigation concludes that, although it is extremely difficult to reduce the lack of precision in color measurement of palm oil, a properly designed and calibrated automatic instrument may still be the better choice because reproducibility and repeatability are required in all standard test methods. The palm oil colorimeter offers a ready and relatively inexpensive solution to the problem of color matches based on visual observations.

Analysis of benzyldimethyldodecylammonium bromide in chemical disinfectants by liquid chromatography and capillary electrophoresis

Two novel analytical methodologies using capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were developed and compared for the determination of benzyldimethyldodecylammonium bromide (BAB) in commercial compound chemical disinfectants. The LC analysis was performed with a Kromasil C 18 ( 200 mm ×4.6 mm, 5 μm) column and a mobile phase of A:B=80:20 (A: acetonitrile, B: 4 mmol/L octanesulfonic sodium—0.02 mol/L acetic sodium, adjusted with acetic acid to pH 5.2) at a flow rate of 1.0 mL/min. Detection was by ultraviolet absorption at 262 nm. The CE analysis was performed in a bare fused-silica capillary with 75 μm i.d. and total length of 46.4 cm with a buffer solution of 50% acetonitrile −50 mmol/L NaH 2 PO 4 , pH 2.24. The applied voltage was 20 kV. Detection was by ultraviolet absorption at 214 nm. Under optimized conditions, the HPLC retention time and CE migration time for BAB was 9.18 and 5.08 min, respectively. Calibration curves of peak area versus concentration gave correlation coefficients of 0.9996 for HPLC and 0.9994 for CE. The detection limits for HPLC and CE were 1.6 mg/L and 0.2 mg/L, respectively. Average recoveries at three concentration levels (50, 100, 200 mg/L for HPLC; 20, 40, 100 mg/L for CE) were 99.94±1.5, 99.64±1.3 and 99.61±0.4% for HPLC and 120.47±2.6, 102.06±8.7 and 103.05±3.0% for CE, respectively. Although both methods were shown to be suitable for the determination of BAB in commercial disinfectant compounds, CE provided analysis with less solvent purchase/disposal and better column efficiency, whereas HPLC provided superior precision.

Analysis of benzyldimethyldodecylammonium bromide in chemical disinfectants by liquid chromatography and capillary electrophoresis

Two novel analytical methodologies using capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were developed and compared for the determination of benzyldimethyldodecylammonium bromide (BAB) in commercial compound chemical disinfectants. The LC analysis was performed with a Kromasil C 18 ( 200 mm×4.6 mm, 5 μm) column and a mobile phase of A:B=80:20 (A: acetonitrile, B: 4 mmol/L octanesulfonic sodium—0.02 mol/L acetic sodium, adjusted with acetic acid to pH 5.2) at a flow rate of 1.0 mL/min. Detection was by ultraviolet absorption at 262 nm. The CE analysis was performed in a bare fused-silica capillary with 75 μm i.d. and total length of 46.4 cm with a buffer solution of 50% acetonitrile −50 mmol/L NaH 2PO 4, pH 2.24. The applied voltage was 20 kV. Detection was by ultraviolet absorption at 214 nm. Under optimized conditions, the HPLC retention time and CE migration time for BAB was 9.18 and 5.08 min, respectively. Calibration curves of peak area versus concentration gave correlation coefficients of 0.9996 for HPLC and 0.9994 for CE. The detection limits for HPLC and CE were 1.6 mg/L and 0.2 mg/L, respectively. Average recoveries at three concentration levels (50, 100, 200 mg/L for HPLC; 20, 40, 100 mg/L for CE) were 99.94±1.5, 99.64±1.3 and 99.61±0.4% for HPLC and 120.47±2.6, 102.06±8.7 and 103.05±3.0% for CE, respectively. Although both methods were shown to be suitable for the determination of BAB in commercial disinfectant compounds, CE provided analysis with less solvent purchase/disposal and better column efficiency, whereas HPLC provided superior precision.

Ligand adsorption of adenine and adenosine on poly(vinyl chloride) bound cobalt(II)–carboxylated diaminoethyl complex

Abstract Ligand adsorption of adenine and adenosine has been studied by using cobalt(II)–poly(vinyl chloride) carboxylated diaminoethyl (PVC–CDAE) resin. Column runs were conducted to study the performance of the ligand exchanger. The adsorption of adenine and adenosine from solutions of different initial concentrations onto resin was measured using by breakthrough technique at 25 °C. The ligand concentration was chosen to be 0.0125–0.2 mmol l−1. The characteristics of the adsorption process were investigated by using Scatchard plot analysis (q/C versus q). And the adsorption behaviour of these ligands on cobalt(II)–PVC–CDAE is expressed by the Langmuir and Freundlich isotherms. The adsorption data with respect to all ligands provide an excellent fit to the Freundlich isotherm, giving correlation coefficients in the range of 0.95–0.99 for the Freundlich isotherm. On the contrary, when the Langmuir isotherm model was applied to these data, a good fit was not obtained for the high ligand concentrations.

Comparative evaluation of 11 scoring functions for molecular docking.

Eleven popular scoring functions have been tested on 100 protein-ligand complexes to evaluate their abilities to reproduce experimentally determined structures and binding affinities. They include four scoring functions implemented in the LigFit module in Cerius2 (LigScore, PLP, PMF, and LUDI), four scoring functions implemented in the CScore module in SYBYL (F-Score, G-Score, D-Score, and ChemScore), the scoring function implemented in the AutoDock program, and two stand-alone scoring functions (DrugScore and X-Score). These scoring functions are not tested in the context of a particular docking program. Instead, conformational sampling and scoring are separated into two consecutive steps. First, an exhaustive conformational sampling is performed by using the AutoDock program to generate an ensemble of docked conformations for each ligand molecule. This conformational ensemble is required to cover the entire conformational space as much as possible rather than to focus on a few energy minima. Then, each scoring function is applied to score this conformational ensemble to see if it can identify the experimentally observed conformation from all of the other decoys. Among all of the scoring functions under test, six of them, i.e., PLP, F-Score, LigScore, DrugScore, LUDI, and X-Score, yield success rates higher than the AutoDock scoring function. The success rates of these six scoring functions range from 66% to 76% if using root-mean-square deviation < or =2.0 A as the criterion. Combining any two or three of these six scoring functions into a consensus scoring scheme further improves the success rate to nearly 80% or even higher. However, when applied to reproduce the experimentally determined binding affinities of the 100 protein-ligand complexes, only X-Score, PLP, DrugScore, and G-Score are able to give correlation coefficients over 0.50. All of the 11 scoring functions are further inspected by their abilities to construct a descriptive, funnel-shaped energy surface for protein-ligand complexation. The results indicate that X-Score and DrugScore perform better than the other ones at this aspect.

Rapid assessment of physico-chemical properties of gelatine using near infrared spectroscopy

The aim of the present study was to investigate the feasibility of near infrared (NIR) spectroscopy for rapid assessment of the Bloom value, viscosity, pH and moisture content of commercial edible gelatines. NIR spectra from both dry gelatine samples and freshly made gels (matured for 30 min) were calibrated against the four parameters. The lowest prediction errors for Bloom value and pH were obtained from the gel spectra, while dry gelatine spectra provided the lowest prediction errors for viscosity and moisture content. However, all four parameters could be predicted from dry gelatine spectra with cross-validated correlation coefficients between 0.80 and 0.86. All calibration models gave correlation coefficients in the region 0.80–0.92.

Regression Analysis for Predicting AU Triumph Tall Fescue Forage Quality from Chemical Composition Data in North Alabama

Lema, M., Knox, N. and Walker, L. 2002. Ṙegression analysis for predicting AU Triumph tall fescue forage quality from chemical composition data in North Alabama. J. Appl. Anim. Res., 22: 81–90. Statistical models may be better alternatives for forage quality estimation as chemical analysis, near infrared reflectance spectroscopy (NIRS) and in vitro digestion are in most instances time-consuming, expensive and hard to obtain and some times utilize hazardous chemicals. A study was conducted to calibrate AU Triumph tall fescue (Festuca arundinacea Shreb) forage quality (WDMD, NDF, ADF and CP contents) predictive equations from chemical analysis data. AU Triumph tall fescue pasture samples collected over a 2-year period were analyzed for crude protein (CP), acid-detergent fiber (ADF), neutral-detergent fiber (NDF), ether extract (EE), acid-detergent lignin (ADL), cellulose (CEL), ash and in vitro dry matter digestibility (IVDMD). Quadratic, cubic and logarithmic relations between independent variables and quality parameter were considered and the data subjected to stepwise regression and correlation analysis. The best fitting equation to predict IVDMD and CP contained only NDF (IVDMD-154.97–1.41 NDF, R2=0.92, RMSE=1.99; CP=41.39–0.51 NDF, R2=0.87, RMSE=0.90) while the best equation to predict NDF contained only EE (NDF=86.80–19.03 EE + 2.98 EE2, R2=0.92, RMSE=1.34). Ash and CEL were the best predictors of ADF (ADF=0.47 + 0.14 Ash + 0.96 CEL, R2=0.99, RMSE=0.04). Model validation using independent samples gave correlation coefficients of validation ranging from 0.86 to 0.97. The results show that tall fescue forage quality parameters (TVDMD, NDF, ADF and CP) can be estimated with high accuracy using simple equations requiring one or two chemical determinations. These equations provide convenient alternatives to chemical analysis for estimating tall fescue forage quality in North Alabama.

Development and validation of a reversed-phase liquid chromatographic method for the assay of lidocaine in aqueous humour samples

A simple, fast and reliable reversed-phase liquid chromatographic method was developed for the assay of lidocaine in human aqueous humour samples. The samples were analysed without any preliminary treatment on a C8 column with UV detection at 225 nm. The mobile phase consisted of methanol/sodium dihydrogen phosphate (30 mM) containing sodium pentansulphonate (10 mM) adjusted to pH 2.5 with phosphoric acid (50:50 v/v). Validation of the method showed it to be precise, accurate and linear over the concentration range of analysis with a limit of detection of 0.2 μg ml −1. The limit of quantitation was 2.5 μg ml −1 with a relative standard deviation of 2.5%. Linear regression analysis in the range 2.5–60 μg ml −1 gave correlation coefficients higher than 0.999. No interference from three commonly co-administered drugs was observed. The method developed was applied to the analysis of lidocaine in aqueous humour samples in order to evaluate and compare the efficacy of two different forms of administration of lidocaine for topical anaesthesia in cataract surgery.