An Apparatus to Obtain a Pure Annihilation Peak

Abstract

A timing discrimination set‐up was developed and the discrimination method was applied to the annihilation gamma ray peak of the ²²Na radioisotope. The annihilation peak was discriminated from the superimposed photon spectrum generated by the Compton effect, backscattering, and background in the 0.5 MeV energy region. A NaI(Tl) inorganic scintillation detector was used to detect the annihilation gamma rays of the radioisotope. Energy resolution of 9.1% was obtained for the discriminated annihilation peak. The developed spectrometer has achieved the discrimination of the annihilation counts and the photo peak counts superimposed on them.     

Design and Optimization of an Electrochemical Equipment for the Synthesis and Evaluation of Conducting Polymers

Abstract

A potentiostat system, focused towards the synthesis and evaluation of conducting polymers, was developed. This equipment consists of two main modules: the acquisition and control module, activated by means of a microcontroller which is connected through serial port to a computer, and the potentiostatic module, specially designed for handling the signals from the synthesis and characterization processes of the polymers. The user environment was programmed with Visual Basic 6. The resolution of the system AD/DA is of 12 bits; this allows sensibilities of 1 nA in current measurements. The achieved potential sweep is between ?2 and +2 V. By means of this equipment, ClO₄ ^?doped polypyrrole (PPy) and biphthalate doped PPy films were synthesized. The conducting polymers were synthesized by potential square waves. The thicknesses of the polymeric films were determined throughout the polymerization charge. The error percentage in the polymerization charge recorded by the developed potentiostat, relative to a commercial potentiostat, was about 6%. The ability to store the charge of the biphthalate PPy (biphthalate) films in potassium biphthalate aqueous solution was determined by cyclic voltammetry at various scan rates.     

Resonance Rayleigh Scattering of K2Zn3[Fe(CN)6]2 Nanoparticles and its Application for the Determination of Vitamin C

Abstract

In Britton-Robinson buffer medium, (pH 4.43), potassium ferricyanide (K₃[Fe(CN)₆]) could react with vitamin C (VC) to produce potassium ferrocyanide (K₄[Fe(CN)₆]), which further reacted with Zn²⁺ to form potassium zinc hexacyanoferate K₂Zn₃[Fe(CN)₆]₂ nanoparticles. The shapes and diameters of the K₂Zn₃[Fe(CN)₆]₂ nanoparticles have been observed with transmission electron microscopy, which showed the shapes of these nanoparticles was cubic and their average sizes were about 50 nm in the presence of 2.0 × 10^?5 mol L^?1 VC. The characteristics of resonance Rayleigh scattering (RRS) spectra of this reaction have been studied. The optimum reaction condition for the determination of VC has been investigated. It was found that the RRS intensity of the system at the RRS peak of 363.4 nm was proportional to the VC concentration in the range of 4.0?80.0 µmol L^?1, and the detection limit (3σ) for VC was 0.075 µmol L^?1. A novel and simple RRS method for the determination of VC based on the formation of K₂Zn₃[Fe(CN)₆]₂ nanoparticles has been established.     

Development of a Setup for the Discrimination of β+ and γ Rays

Abstract

A β⁺–γ discrimination set‐up was developed and applied to the ²²Na radioisotope. The radioisotope emits positrons (β⁺) and these positrons create γ rays by annihilating with electrons. These annihilation γ rays were used here, and the discrimination between these positrons and γ rays was investigated by the coincidence measurement between time signals and the energy signals. The detection system presented here uses a 3 inch (diameter) by 3 inch (length) NaI(Tl) inorganic scintillation detector for γ detection and 3 inch (diameter) by 3 inch (length) plastic scintillation detector for β⁺ detection.     

Improving the MCA Spectra of BC‐400 Plastic Scintillation Detectors at Room Temperature

Abstract

In the presented work, the leading edge timing and constant fraction discrimination timing techniques were applied to beta rays emitted from a ¹³⁷Cs radioactive source through the developed spectrometers in order to improve the beta energy spectrum of the source. The energy spectra, with and without the techniques, were obtained with a BC‐400 plastic scintillation detector. The obtained spectra were compared with each other for the elimination of spurious pulses, which rise from background, backscattering, scattering, and any radiations other than the source, on the multichannel analyzer output.     

Wear Behavior of Al/CMA-Type Al3Mg2 Nanocomposites Fabricated by Mechanical Milling and Hot Extrusion

In the current research, the wear behavior of an aluminum matrix nanocomposite material prepared via mechanical milling and hot extrusion was investigated. The sample powders were milled at different milling times up to 15 h to produce nanostructure powders. Mechanical milling was used to prepare nanocomposite samples by the addition of 10 wt% of Al₃Mg₂ nanoparticles into the Al matrix. A pin-on-disk setup was used to evaluate the wear properties of the hot-extruded samples under dry condition. Hardness values were used for further explanation of the observed results. Scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDS) analyzer was used to analyze the worn surfaces. The results revealed a lower friction coefficient and a lower wear rate for the unmilled nanocomposite sample in contrast to a commercial pure Al one. The same pattern was also observed in the milled nanocomposite samples with respect to the base matrix.     

Determination of R‐Deprenyl using a Maltodextrin‐Based Enantioselective,Potentiometric Membrane Electrode

Abstract

The enantioselective, potentiometric membrane electrode (EPME) based on maltodextrin with dextrose equivalence (DE) 16.5–19.5 is proposed for the assay of R‐deprenyl. The linear concentration range for the proposed electrode is 10^?10?10^?3 mol L^?1. The slope of the electrode is 53.1 mV per decade of concentration. The detection limit is 3.6×10^?11 mol L^?1. The proposed electrode could be reliably employed for the assay of R‐deprenyl raw material and its pharmaceutical formulation, Lentogesic tablets.     

Comparison of some physical techniques for detection of spoilage in apple juice inoculated with Saccharomyces cerevisiae: Optical and photothermal methods

Abstract

Several physical techniques were used to study the extent of spoilage in apple juice deliberately inoculated with yeast (concentration of Saccharomyces cerevisiae ranged from 25 cells mL^?1 to 2.5 × 10⁶ cells mL^?1, respectively) and their performance compared in terms of detection limit achieved. The optical methods used in this investigation rely on the measurement of either absorption [as is the case for classical spectrophotometry (SP) and the so called optothermal window (OW), a variant of a photothermal method], or scattering [examples are turbidimetry (TB), laser scattering (SC), and laser speckle fluctuation (SF)]. It is shown that the presence of yeast increases both optical absorption and scattering. The most favorable detection limit (25 cells mL^?1) and a highest (nearly 10⁴) dynamic range, combined with a good linearity, were obtained with the experimental set‐up for SC. In addition, the extent of correlation between different methods was determined using two markedly different reference substances, i.e., (i) the mixture of apple and blackcurrant juices, representing a strongly absorbing sample, and (ii) diluted (dilution factor of 10³) milk as a strong scatterer. Finally, one has monitored the progress of a spontaneous spoilage process in the inoculated juices stored at 5°C under aerobic conditions.     

Development and machinability evaluation of MgO doped Y-ZTA ceramic inserts for high-speed machining of steel

ABSTRACT

In current high productivity manufacturing era, it is necessary to develop non-conventional newer tool materials. Here, an attempt has been made for developing MgO doped zirconia-toughened alumina (Mg-ZTA) using powder metallurgy process route. The 3 mol% yttria stabilized zirconia (YSZ) (10 wt%), alumina (Al₂O₃) (90 wt%) with varying percentage of magnesium oxide (MgO) (0–1 wt%) are mixed to study the phase transformation and uniaxially pressed into square inserts with 0.8 mm nose radius and sintered at 1,600ºC for 1 h in pressure less condition. The maximum hardness of 17.04 GPa, fracture toughness of 5.09 MPa m^1/2 and flexural strength of 502 MPa, respectively, has been reached at 0.6 wt% of MgO due to more metastable tetragonal phase. The performance of the insert has been evaluated by machining AISI 4340 steel (radius 75 mm) in lathe. The performance with respect to flank wear, cutting force and surface roughness is quite impressive at different cutting speed even after 20 min of machining. It can be inferred that MgO doped ZTA insert can be used for medium to high-speed machining in current manufacturing scenario and is very promising to replace carbide or coated carbide inserts in coming days.     

Rapid and Sensitive Determination of Nucleic Acids by Enhanced Resonance Light Scattering Spectroscopy of Tetraphenyl Porphyrin Cobalt(II)Chloride

Abstract

A novel probe, tetraphenyl porphyrin Cobalt(II)chloride (CoTPPCl), was first developed for the determination of nucleic acids at a nanogram level by a resonance light scattering (RLS) technique. Under optimum conditions, the weak RLS signal of CoTPPCl was enhanced greatly by nucleic acids at 444.0 nm; the enhanced RLS intensity is proportional to the concentration of nucleic acids in the range of 0.05–3.5 mg L^?1 for calf thymus DNA and 0.03–4.2 mg L^?1 for fish sperm DNA. The detection limits (3δ) are 3.5 ng mL^?1 for calf thymus DNA and 4.5 ng mL^?1 for fish sperm DNA, respectively. The results show that determination of nucleic acids with CoTPPCl as a probe is much more sensitive than with α, β, γ, δ‐ tetrakis[4‐(trimethylammoniumyl)phenyl]porphine (TAPP). Synthetic samples and plasmid DNA extracted from K‐12‐HB101 colt were determined with satisfactory results.     

PVC Membrane Sensor for Potentiometric Determination of Atropine in Some Pharmaceutical Formulations

Abstract

The construction and general performance of a novel potentiometric membrane sensor for determination of atropine has been developed. It is based on the formation of the ion association complex of the atropinium cation with phosphotungstate counter anion as electroactive material dispersed in a PVC matrix, β‐Cyclodextrin and o‐nitrophenyl octyl ether serve as a plasticizer. The sensor shows a fast, stable, near Nernstian response for 1×10^?2 M to 1×10^?6 M atropine at 25°C over the pH range of 3–8 with a cationic slope of 51±0.5 mV/decade. The lower detection limit is 8×10^?7 M and the response time is 20–45 sec. Selectivity coefficients of atropine, relative to a number of interfering substances, were investigated. There are negligible interferences caused by most of the studied cations, anions, and pharmaceutical excipients. The direct determination of atropine shows an average recovery of 98.6% and a mean relative standard deviation (RSD) of 1.6% at 100 µg/mL. The results obtained by determination of atropine in some formulations (atropine injection and eye drops) are favorably comparable with those obtained by the British Pharmacopoeia method. The developed membrane electrode has been used as end point indicator electrode for some potentiometric titrations.     

SENSITIVE L-CYSTEINE AMPEROMETRIC SENSOR BASED ON A GLASSY CARBON ELECTRODE MODIFIED BY MnO2 NANOPARTICLES

A sensitive amperometric sensor for the determination of L-cysteine was fabricated by electrodeposition of modified MnO₂ nanoparticles on a glassy carbon electrode. The morphology of the nanoparticles was characterized by scanning electron microscopy. Cyclic voltammetry was applied to investigate the mechanism of film formation and the electrochemical properties of the MnO₂ nanoparticle-modified electrode. The results of electrochemical experiments showed that the modified electrode had a favorable catalytic ability for the electrochemical oxidation of L-cysteine. Under optimized conditions, the MnO₂ nanoparticle-modified electrode exhibited a linear dependence on the concentration of L-cysteine from 1.0 × 10^?6 to 6.4 × 10^?4 M, and a detection limit of 8.0 × 10^?7 M (signal/noise = 3). The modified electrode was highly resistant towards typical inorganic salts and some biomolecules. In addition, the sensor was applied for the determination of L-cysteine in human serum with high accuracy, demonstrating its potential for practical applications.     

Spectrophotometric Determination of Silicon in Rice and Alloy Steel Samples

Abstract

In the medium of 0.128 mol/L nitric acid and 0.450 mol/L sulfuric acid, silicon(IV) and ammonium molybdate form molybdosilicate blue blue complex in the presence of ascorbic acid. The maximum absorption wavelength of the complex locates at 810 nm. The apparent molar absorptivity is ε_810 nm = 3.18 × 10⁴ L · mol^?1 · cm^?1. Beer's law is followed over the range of 0 ～ 1.0 µg/mLof silicon(IV). The present method has been successfully applied to the determination of silicon in rice and alloy steel samples.     

Simultaneous Determination of Six Trace Elements in Plant Medicines by Derivative Adsorption Waves in Conjunction with a Microwave Technique

Abstract

Complex adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) in substrate solution (pH=9.26) of diacetyldioxime‐ammonia‐ammonium chloride‐sodium citrate‐gelatin‐sodium sulfite were studied and a new method for determination of the six trace elements in aqueous solutions was developed. The results show that there are sensitive adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) complexes at about ?0.45, ?0.61,?0.78, ?1.07, ?1.23, and ?1.38 V, respectively. The method is easy to operate and is able to determine these trace elements in aqueous solutions rapidly and simultaneously. When the signal‐to‐noise ratio equals 3, the detection limits of copper, lead, cadmium, nickel, cobalt, and zinc are 3.2×10^?4, 4.8×10^?3, 1.9×10^?3, 1.7×10^?5, 2.1×10^?6, and 1.0×10^?3 µg/cm³. Good linear relationships exist between the concentrations and the current peaks when copper, lead, cadmium, nickel, cobalt, and zinc concentrations are within 6.5×10^?4～10⁰, 9.3×10^?3～10, 4.1×10^?3～10, 3.2×10^?5～10^?1, 4.0×10^?6～10^?2, and 2.1×10^?3～10 µg/cm³, respectively. In conjunction with a microwave assimilation technique, the method has been used in the rapid and simultaneous determination of these trace elements in some plant medicines with satisfactory results.     

Construction of an Optical Sensor for Cobalt Determination Based on Methyltrioctylammonium Chloride Immobilized on a Polymer Membrane

Abstract

An optical sensor has been designed for the determination of cobalt by spectrophotometry. The sensing membrane is made by immobilizing methyltrioctylammonium chloride on a triacetylcellulose membrane. In the presence of Co(II) and thiocyanate ions, the colorless membrane changes to blue. The response time of the optode was about 7 min. The sensor can readily be regenerated with 0.02 mol L^?1 sodium oxalate solution. This optode is stable and can be stored under water for more than a month without reagent leaching. The calibration curve was linear in the range of 8.5×10^?6–1.3×10^?4 mol L^?1 of Co(II) ion with a limit of detection 5.9×10^?6 mol L^?1. The relative standard deviations for seven replicate measurements of 3.4×10^?5 and 1×10^?4 mol L^?1 of Co(II) were 1.58 and 1.10%, respectively. The sensor was successfully applied to the determination of cobalt in food samples and vitamin B₁₂ ampoule.     

Electrochemical Behavior of Uric Acid at a Meso‐2,3‐Dimercaptosuccinic Acid Self‐Assembled Gold Electrode

Abstract

The fabrication and electrochemical characteristics of a meso‐2,3‐dimercaptosuccinic acid (DMSA) self‐assembled monolayer modified gold electrode were investigated. The DMSA self‐assembled electrode can enhance the electrochemical stability of uric acid (UA) and the electrochemical reaction of UA on the DMSA electrode has been studied by cyclic voltammetry and electrochemical quartz crystal microbalance. Some electrochemical parameters, such as diffusion coefficient, standard rate constant, electron transfer coefficient, and protons transfer number have been determined for the electrochemical behavior on the DMSA self‐assembled monolayer electrode. The electrode reaction of UA is an irreversible process which is controlled by the diffusion of UA with two electrons and two protons transfer at the DMSA/Au electrode. In phosphate buffer (pH 5.0), the peak current is proportional to the concentration of UA in the range of 8.0×10^?5?1.0×10^?2 mol L^?1 and 8.0×10^?5?8.0×10^?3 mol L^?1 for the cyclic voltammetry and differential pulse voltammetry methods with the detection limits of 1×10^?6 and 8×10^?7 mol L^?1, respectively. This method can be applied to the determination of the UA concentration.     

New approach to metamerism measurement on halftone color images

There is often a phenomenon depending on dominant tones which results in the end users dissatisfaction with halftone color reproduction. This phenomenon is known as “metamerism” and it is the subject of research for many scientists.The metamerism on halftone color images with different dominant tones (blue, red, green and yellow) was researched in this paper, at the light sources D₅₀, D₆₅ and daylight. The results of the objective and visual evaluation were presented on the basis of colorimetric measurement of the grey balance patch, by the means of MacAdam ellipsoids in three dimension CIE L^*a^*b^* system. Both the metamerism index MI and the ellipsoid volume have also been calculated.This paper confirms that the metamerism of the halftone color images can be estimated by measuring CIE L^*a^*b^* values of the grey balance patch and by calculating MacAdam ellipsoids.     

On‐Line Preconcentration System for Cobalt Determination in Bee Honey Using Flow Injection‐Flame AAS

Abstract

A methodology for the on‐line preconcentration and determination of cobalt by flame atomic absorption spectrometry (FAAS) coupled with flow injection (FI) in bee honey samples is proposed. For the retention of cobalt, 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol (5‐Br‐PADAP) complexing reagent, and Amberlite XAD‐7 resin were used, at pH 9.5. The Co‐(5‐Br‐PADAP) complexes were completely removed from the column with ethanol. An enrichment factor (EF) of 50‐fold for a sample volume of 50 mL was obtained. The detection limit (DL) for the preconcentration of 50 mL of aqueous solution was 0.18 µg L^?1. The precision for 10 replicate determinations at the 10 µg L^?1 cobalt levels was 3.6% relative standard deviation (RSD), calculated with peak heights obtained. The calibration graph using the preconcentration system for cobalt was linear with a correlation coefficient of 0.9997 at levels near the DL, up to at least 300 µg L^?1. The method was successfully applied to determination of total cobalt in honey samples.     

Rapid and Highly Sensitive Method for Protein Determination in Biological Samples with m‐Nitrophenylfluorone‐Mo(VI) Complex as a Spectral Probe

Abstract

A simple, rapid, highly sensitive, and selective method for detecting protein in biological samples has been developed, which is based on the interaction between protein and m‐nitrophenylfluorone‐Mo(VI) complex as a spectral probe. The optimum condition for the reaction is investigated. Bovine serum albumin (BSA) obeys Beer's law up to 10 µg · mL^?1, having a molar absorption coefficient of 8.51×10⁶ L · mol^?1 · cm^?1 at 535 nm. Many amino acids and metal ions do not interfere. The results of determination for biological samples are comparable to those obtained by the Bradford method. Meanwhile, the binding number is also determined.     

Flow Injection Chemiluminescence Analysis of Diphenhydramine Hydrochloride and Chlorpheniramine Maleate

Abstract

A new chemiluminescence (CL) method, using flow injection, is described for the determination of diphenhydramine hydrochloride and chlorpheniramine maleate. The method is based on the restraining effects on the CL reaction of luminol‐potassium ferricyanide in alkaline solutions. The various experimental parameters affecting the chemiluminescence intensity were studied carefully and incorporated into the procedure. The method allows the determination of 1.0–100 µg mL^?1 diphenhydramine hydrochloride and 0.1–10.0 µg mL^?1 chlorpheniramine maleate. The detection limits of the method are 0.3 µg mL^?1 for diphenhydramine hydrochloride and 0.02 µg mL^?1 for chlorpheniramine maleate. The method was successfully applied to the determination of diphenhydramine hydrochloride and chlorpheniramine maleate in pharmaceutical preparations.