Optimum Working Range Research Articles

Testing for Green Compression Strength and Permeability Properties on the Tailing Sand Samples Gathered from Ex Tin Mines in Perak State, Malaysia

Permeability and green compression strength are among the important mechanical properties and considered much in the sand casting mould preparation. These molding sand properties play a vital role in determining the optimum moisture content for making green sand casting mould. Tailing sand is the residue mineral from tin extraction, which contains between 94% and 99.5% silica and in abundance in Kinta Valley of state of Perak, Malaysia. In this research work, samples of tailing sands were gathered from four identified ex tin mines located at the Perak State, Malaysia. They were investigated by the standards and testing procedures prescribed by the American Foundrymen Society (AFS). Sand specimens of size Ø50 mm×50 mm in height from various sandwater ratios bonded with 4% clay were compacted on applying three ramming blows of 6666 g each by using a Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using Ridsdale-Dietert universal sand strength machine and permeability number with Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured using moisture analyzer. Samples with moisture content ranging from 3 to 3.5% were found to have optimum working range with effective green compression strength and permeability.

Testing for Green Compression Strength and Permeability Properties on the Tailing Sand Samples Gathered from Ex Tin Mines in Perak State, Malaysia

Permeability and green compression strength are among the important mechanical properties and considered much in the sand casting mould preparation. These molding sand properties play a vital role in determining the optimum moisture content for making green sand casting mould. Tailing sand is the residue mineral from tin extraction, which contains between 94% and 99.5% silica and in abundance in Kinta Valley of state of Perak, Malaysia. In this research work, samples of tailing sands were gathered from four identified ex tin mines located at the Perak State, Malaysia. They were investigated by the standards and testing procedures prescribed by the American Foundrymen Society (AFS). Sand specimens of size Ø50 mm×50 mm in height from various sandwater ratios bonded with 4% clay were compacted on applying three ramming blows of 6666 g each by using a Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using Ridsdale-Dietert universal sand strength machine and permeability number with Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured using moisture analyzer. Samples with moisture content ranging from 3 to 3.5% were found to have optimum working range with effective green compression strength and permeability.

An optofluidic prism tuned by two laminar flows

This paper presents a tunable optofluidic prism based on the configuration of two laminar flow streams with different refractive indices in a triangular chamber. The chambers with 70° and 90° apex angles are designed based on simulation results, which provide the optimum working range and avoid recirculating flows in the chambers. In addition, a hydrodynamic model has been developed to predict the tuning of the prisms by the variation in the flow rates. Prisms with different refractive indices are realized using benzyl alcohol and deionized (DI) water as the inner liquids, respectively. The mixture of ethylene glycol and DI water with an effective refractive index matched to that of the microchannel is used as the outer liquid. The apex angle of the prism is tuned from 75° to 135° by adjusting the ratio of the two flow rates. Subsequently, the deviation angle of the output light beam is tuned from -13.5° to 22°. One of the new features of this optofluidic prism is its capability to transform from a symmetric to an asymmetric prism with the assistance of a third flow. Two optical behaviours have been performed using the optofluidic prism. First, parallel light beam scanning is achieved with a constant deviation angle of 10° and a tuning range of 60 μm using the asymmetric prism. The detected output light intensity is increased by 65.7%. Second, light dispersion is experimentally demonstrated using 488-nm and 633-nm laser beams. The two laser beams become distinguishable with a deviation angle difference of 2.5° when the apex angle of the prism reaches 116°.

Direct hapten coated immunoassay format for the detection of atrazine and 2,4-dichlorophenoxyacetic acid herbicides

A novel immunoassay format employing direct coating of small molecular hapten on microtiter plates is reported for the detection of atrazine and 2,4-dichlorophenoxyacetic (2,4-D). In this assay, the polystyrene surface of microtiter plates was first treated with an acid to generate –NO 2 groups on the surface. Acid treated plates were further treated with 3-aminoprpyltriethoxysilane (APTES) to functionalize the plate surface with amino groups for covalent linkage to small molecular hapten with carboxyl groups. The modified plates showed significantly high antibody binding in comparison to plates coated with hapten–carrier protein conjugates and presented excellent stability as a function of the buffer pH and reaction time. The developed assay employing direct hapten coated plates and using affinity purified atrazine and 2,4-D antibodies demonstrated very high sensitivity, IC 50 values for atrazine and 2,4-D equal to 0.8 ng mL −1 and 7 ng mL −1, respectively. The assay could detect atrazine and 2,4-D levels in standard water samples even at a very low concentration upto 0.02 and 0.7 ng mL −1 respectively in the optimum working range between 0.01 and 1000 ng mL −1 with good signal reproducibility ( p values: 0.091 and 0.224 for atrazine and 2,4-D, respectively). The developed immunoassay format could be used as convenient quantitative tool for the sensitive screening of pesticides in samples.

The signal characteristics of reflected spectra of fiber Bragg grating sensors with strain gradients and grating lengths

Among the numerous types of fiber optic sensors, FBG sensors are currently the most actively studied sensors due to their good multiplexing capabilities. The demodulation method of FBG sensors is based on detecting the wavelength shift of their sensor peaks. Properties such as strain, temperature, etc. can be measured simply by detecting them. However, the signal stability of FBG sensors can be influenced by strain gradients induced by structural geometry or cracks on the surface when FBG sensors are embedded into or attached on the structure. In this study, the signal characteristics of reflected spectra of FBG sensors were verified under strain gradients and the correlation between the grating length of FBG sensors and strain gradients were investigated quantitatively. From the experimental results, the optimum working range of the FBG sensors, where FBG sensors could be used without split of the sensor peak, was shown when they were under strain gradients.

Flow Injection Analysis Spectrophotometric Determination of Palladium

A simple and specific method for flow injection analysis (FIA) spectrophotometric determination of Pd is described. The method is based on color reaction of Pd(II) with organic reagent, i.e., N‐phenylbenzimidoylthiourea (PBITU) over acidity range, 0.2–2.0 M HCl in the 10% (v/v) ethanolic solution. The value of apparent molar absorptivity of the yellow colored complex in the term of Pd is 1.20 × 104 L mol−1 cm−1 at λmax 345 nm. The detection limit (causing more absorbance than 3s) of the method is 80 ng mL−1 of Pd. The optimum working range was 0.25–10.0 µg mL−1 of Pd with slope, intercept, and correlation coefficient of 0.059, 0.006, and +0.99, respectively. The RSD of the method was ±1.1% for six replicate measurements at level of 2.0 µg mL−1 of Pd. The sample throughput of the method is 120 samples hr−1. The composition of the complex is discussed. The method is specific for the determination of Pd as none of the tested ions interfered. The method has been applied for the determination of Pd in the catalytic materials.

Construction and analytical characterization of Prussian-Blue-based carbon paste electrodes and their assembly as oxidase enzyme sensors.

This paper reports on the development and characterization of Prussian Blue-modified carbon paste electrodes. New methods of matrix modification with Prussian Blue are reported. Two different carbon pastes have been prepared, using mineral oil or solid paraffin, thus obtaining different types of sensors whose behavior toward the electrochemical reduction of hydrogen peroxide has been fully characterized. Results obtained with Prussian Blue-modified electrodes showed a long operational lifetime, an excellent stability in a wide range of pH (3-9), a high sensitivity, and a fast response time. In addition, the coupling of solid carbon paste modified with Prussian Blue and the enzymes glucose oxidase and choline oxidase led to the assembling of biosensors that showed an optimum working range at alkaline pH.

Analysis of high-purity reagents using automatic on-line column preconcentration-separation and electrothermal atomic absorption spectrometry

A fully automatic flow-injection on-line column preconcentration and separation procedure for electrothermal atomic absorption spectrometry is described for the determination of cadmium and lead in high-purity reagents. A microcolumn with 9 μL of solid sorbent, introduction of air prior to elution, and use of methanol as the eluent made it possible to elute the sorbed analyte quantitatively with only 80 μL of solvent. The total eluate volume was transferred into the graphite tube which was pre-heated to 80°C using a flow rate of 0.08 mL min−1 which allowed the solvent to evaporate in part during eluate introduction. The efficiency of the total procedure was 0.63 and 0.65, and the enrichment factor was 62 and 64 for cadmium and lead, respectively, compared with the direct introduction of 30 μL of an aqueous solution. The sample throughput was 13 h−1 for a sample loading time of 60 s and the detection limits (3 σ) were 0.7 and 4.5 ng L−1 for cadmium and lead, respectively. The relative standard deviation of the entire procedure in the optimum working range was typically around 3% (n=6). A number of high purity (suprapure) and analytical grade (pro analysi) reagents were analyzed, and spiking experiments resulted in recoveries of 97–104%.

Computational studies of submicron probing of polymer surfaces. I

The atomistic details of the interaction of an atomic force microscopic (AFM) probe with a polymer surface are examined by using the molecular-dynamics method. It is found that the perturbation of the AFM probe can produce a deformation of the local structure of the polymer surface. The dynamics study reveals how the structural changes evolve during the surface probing experiment, and whether the deformations result in permanent or reversible structural damage upon removing the probe. The effects of probe features (radius of curvature) and load force on the surface deformation(s) and image resolution are investigated in both a constant-force and constant-height AFM mode. Load forces between 10−8 and 10−11 N were determined to be an optimum working range for nondestructive AFM probing of polymer surfaces, and consequently for well-resolved surface image production.

Determination of the optimum working range in spectrophotometric procedures

A brief introduction to the topics of covariance and variance is given in this paper. An abstract vectorial space, the “precision pattern space” is introduced in order to find the general expression for the law of random error propagation. A new approach to the determination of the optimum working range in spectrophotometric procedures has been developed. The method involves the use of the calibration curve and the application of the Laplacian operator to concentration. The general expression reported for the relative error in concentration tends towards the classical photometric error expression in limiting cases.

Palladium nitrate-magnesium nitrate modifier for graphite furnace atomic absorption spectrometry. Part 2. Determination of arsenic, cadmium, copper, manganese, lead, antimony, selenium and thallium in water

If the palladium nitrate-magnesium nitrate modifier is applied to the analysis of water, a common set of conditions for the determination of As, Cu, Mn, Pb, Sb and Se can be used. For Cd and Tl lower pyrolysis and atomisation temperatures are required. Twenty-one possible interferents were investigated at maximum concentrations between 1 and 500 mg l–1 and only two were found to have an effect greater than ±10%. The determination of Tl was affected by sodium chloride at concentrations above 100 mg l–1, hence the addition of Li is recommended to control this interference. Five mg l–1 of Fe decreased the Se signal by about 15% when deuterium-arc background correction was used but had no influence in an instrument with Zeeman-effect background correction. For an instrument with continuum source background correction it was also necessary to determine Cu using the secondary resonance line at 327.4 nm because of spectral interference due to Pd at the primary resonance line. Precision was about 1% in the optimum working range and between 2 and 5% at 0.05 A s. Detection limits (2.33 σ) were 1.2 µg l–1 for As, 0.02 µg l–1 for Cd, 0.3 µg l–1 for Cu, 0.45 µg l–1 for Mn and Pb, 1.2 µg l–1 for Sb, 0.6 µg l–1 for Se and 0.8 µg l–1 for Tl.

Cold vapor atomic absorption spectrometric determination of mercury using sodium tetrahydroborate reduction and collection on gold

Sodium tetrahydroborate(III) is equivalent to or better than tin(II) chloride as a reducing agent for mercury in cold vapor atomic absorption spectrometry using collection on gold. Concentrations of copper, silver, nickel, iodide, antimony, arsenic, bismuth and selenium typically found in water or waste water do not interfere. Prerequirements for satisfactory performance are that the gold is at a temperature below 100‡C during collection of mercury and that the gas from the reaction flask is washed with sodium hydroxide and dried with magnesium perchlorate. All determinations were carried out in 5 mol l−1 hydrochloric acid and in the presence of 200 mg l−1 iron(III). Detection limits (3σ) of 0.15 ng absolute, and of 15 ng l−1 or 3 ng l−1, using 10 ml or 50 ml solution, respectively, are obtained. The analytical curve is linear to 40 ng, and the relative standard deviation in the optimum working range is better than 2%.

Bis(4-hydroxypent-2-ylidene)diaminoethane as a reagent for copper

A rapid, simple extractive spectrophotometric method for the determination of copper, based on the formation of a purple complex between the metal and bis(4-hydroxypent-2-ylidene) diaminoethane is described. The properties of the reagent and some of its colour reactions with other metal ions are reported. The copper complex has an absorption maximum at 540 nm and its molar absorptivity in chloroform is 1.36 × 10 3 1.mole −1.cm −1. Beer's law is valid up to 384 μg/ml with an optimum working range of 36–334 μg/ml. Job's method and the molar ratio method indicate 1:2 (metal/ ligand) composition for the complex. The effects of pH, time, temperature, order of addition of reagents, reagent concentration, and interference from various ions are reported. The method is applied to the direct determination of copper in copper-base alloys in the presence of zinc and some other metals without prior separation.

Modified Method for Carbadox in Feeds: Collaborative Study

The official first action method for carbadox in swine feed, 42.C01-42.C04, was modified in 2 respects. First, the samples were leached overnight at room temperature instead of boiled for 1 hr. This change avoided problems with overheating and excessive evaporation. Second, the dilution scheme for samples spiked with carbadox standard solution was changed to give absorbance values that were within the optimum working range of all types of spectrophotometers. The modified procedure was collaboratively studied by 21 laboratories. The repeatability standard deviation (sigma0) and reproducibility standard deviation (sigmax) were sigma0 = 0.00029% and sigmax = 0.00056% (8.9% of grand mean) for feeds containing 0.00617% carbadox; and sigma = 0.0012% and sigmax = 0.0019% (9.3% of grand mean) for feeds containing 0.0198% carbadox. The between-laboratory variance ratio was significant for feeds containing 0.0198% carbadox. The mean per cent of intent values for feeds containing 0.00617% carbadox and 0.0198% carbadox were 102% and 104%, respectively. In general, the statistical results were comparable to those previously obtained for the official first action method. Consequently, the modified procedure is not recommended as a replacement for the official first action method.

Determination of the optimum working range from a calibration curve for colorimetric analysis with an “autoanalyzer”

A study has been made of the types and distribution of errors in determining the optimum working range from a calibration curve for automated analysis. Three error equations are derived for the fitting of a linear, quadratic or cubic curve, involving a thorough statistical analysis of the data. The errors from a set of silica and alumina standards, requiring a quadratic and cubic fit respectively, compare favourably with replicate analyses of standard rocks done on a previous occasion.

Optimum working range for the study of hemoproteins by reflectance spectroscopy

Optimum working range for the study of hemoproteins by reflectance spectroscopy

Determination of selenium by the ring oven technique

A simple semi-quantitative fluorometric method for selenium analysis has been developed which employs the reagent 2,3-diaminonaphthalene and the ring oven technique. By this procedure selenium can be determined to 10 ppb; the optimum working range is 20–80 ppb. The concentration of selenium is ascertained by visual observation of the rings under long wavelength UV light.

Dosage en phase gazeuse du molybdène dans l'hexafluorure d'uranium par spectroscopie d'absorption atomique

A procedure for the determination of molybdenum hexafluoride in uranium hexafluoride by atomic absorption spectrometry, without any hydrolysis, is described. Gaseous uranium hexafluoride is introduced into a premix burner and molybdenum determined from a calibration curve obtained with synthetic mixtures of uranium hexafluoride and molybdenum hexafluoride. The optimum working range is between 10 and 50 ppm of molybdenum in uranium. The detection limit obtained is 2 ppm.