Plantlet Regeneration from Callus Cultures of Selected Genotype of <Emphasis Type="Italic">Aloe vera</Emphasis> L.—An Ancient Plant for Modern Herbal Industries

Aloe vera L., a member of Liliaceae, is a medicinal plant and has a number of curative properties. We describe here the development of tissue culture method for high-frequency plantlet regeneration from inflorescence axis-derived callus cultures of sweet aloe genotype. Competent callus cultures were established on 0.8% agar-gelled Murashige and Skoog’s (MS) basal medium supplemented with 6.0 mg l⁻¹ of 2,4-dichlorophenoxyacetic acid (2,4-D) and 100.0 mg l⁻¹ of activated charcoal and additives (100 mg l⁻¹ of ascorbic acid, 50.0 mg l⁻¹ each of citric acid and polyvinylpyrrolidone, and 25.0 mg l⁻¹ each of l-arginine and adenine sulfate). The callus cultures were cultured on MS medium containing 1.5 mg l⁻¹ of 2,4-D, 0.25 mg l⁻¹ of Kinetin (Kin), and additives with 4% carbohydrate source for multiplication and long-term maintenance of regenerative callus cultures. Callus cultures organized, differentiated, and produced globular embryogenic structures on MS medium with 1.0 mg l⁻¹ of 2,4-D, 0.25 mg l⁻¹ of Kin, and additives (50.0 mg l⁻¹ of ascorbic acid and 25.0 mg l⁻¹ each of citric acid, l-arginine, and adenine sulfate). These globular structures subsequently produced shoot buds and then complete plantlets on MS medium containing 1.0 mg l⁻¹ of 6-benzylaminopurine and additives. A hundred percent regenerated plantlets were hardened in the greenhouse and stored under an agro-net house/nursery. The regeneration system defined could be a useful tool not only for mass-scale propagation of selected genotype of A. vera, but also for genetic improvement of plant species through genetic transformation.     

Application de l’Analuyse par Radioactivation Neutronique et du Calcul Electronique au Dosage non Destructif de Traces de Chlore dans les Silices-alumines

A method applicable for serial determination of traces of chlorine in SiO₂−Al₂O₃ catalysts by neutron activation is described. The results are evaluated by means of a computer. The³⁸Cl activity is subtracted from the activity of the interfering components (⁵⁶Mn,²⁴Na) and this enables a direct γ-spectrometric determination. In praxis ten samples should be irradiated simultaneously and for this reason 3 standards are irradiated together with the samples to correct for the fluxus gradient. The reproducibility of the method is better than 2 per cent for 10–300 mg samples with a Cl content of 10 ppm.      

Callus induction and plant regeneration from different explants of Actinidia deliciosa

In this study, an efficient procedure was developed for callus induction and regeneration of kiwifruit (Actinidia deliciosa) using different organs of shoots developed under in vitro conditions. Effects of explants source and media (M₁, 1.0 mg l⁻¹ BA + 2.0 mg l⁻¹ 2,4-D–M₂, 1.0 mg l⁻¹ NAA + 2.0 mg l⁻¹ 2,4-D) on initiation of callus were examined in order to obtain callus for organogenesis. The best callus for plant regeneration was obtained from leaf explants on Murashige and Skoog’s medium (MS) supplemented with M₂. Formation of callus from leaf of kiwifruit (A. deliciosa) was cultured in MS medium containing different concentration of N⁶-benzylaminopurin (BA; 0.0, 1.0, 2.0, 4.0, 6.0, 8.0 mg l⁻¹) for callus proliferation and plant regeneration. Although the first shoot formation was appeared in medium containing 6.0 and 8.0 mg l⁻¹ BA, the best shoots formation was obtained in medium with 4.0 mg l⁻¹ BA.     

The determination of manganese in seawater,surface water and rainwater by neutron activation analysis

A rapid procedure for the determination of manganese in seawater, surface water and rainwater is presented. The method is based on preconcentration of manganese as the pyrrolidine-dithiocarbamate (APDC) complex on a layer of active carbon and determination of the manganese in the carbon concentrate by neutron activation analysis. Provided the blank of the carbon can be kept low the limit of determination is 50 ng Mn·l⁻¹, when a sample of 200 ml is processed.     

Halogen speciation in the rat thyroid: Simultaneous determination of bromine and iodine by short-term INAA

The study describes a mode of non-destructive simultaneous determination of bromine and iodine concentrations, by reactor instrumental neutron activation analysis (INAA) in the regime of short-term activation. Under the conditions of 1-minute activation in the neutron flux of 8.0·10¹³ n·cm⁻²·s⁻¹, it was possible to determine reliably as little as 5·10⁻⁸ g bromine and about 10⁻⁷ g iodine in matrices of a given type and of the mass of about 5 mg dry weight. We applied this method for the determination of Br and I concentrations in the whole rat thyroid gland as well as for the halogen speciation in fractions separated from this organ.     

Determination of potassium in beet by 14 MeV neutron activation analysis

The applicability of 14 MeV neutron activation analysis for the determination of K in beet has been investigated by measuring the 2.167 MeV gamma-line from the decay of³⁸gK produced in the³⁹K(n, 2n) reaction. Beet samples were treated in different solutions of KCl and HgCl₂ to study the diffusion of K⁺ ions into the beet cells. The contribution of the gamma-line to the measured peak area from³⁸Cl produced in the³⁷Cl(n, γ) reaction was found to be 1%. Results obtained by fast neutron activation analysis and by flame spectrometry have been compared, and good agreements were found.     

Voltammetric determination of 2,4-dinitrophenol and 2,5-dinitrophenol using a poly-aspartic acid modified electrode1

In pH 5.0, 0.1 mol l⁻¹ NaAc-HAc buffer solution, 2,4-dinitrophenol and 2,5-dinitrophenol exhibited sensitive and distinguishable voltammetric responses at the glassy carbon electrode modified with poly-aspartic acid. By measuring the reduction peak currents of nitro groups in different positions, dinitrophenol isomers have been determined simultaneously and quantitatively. The linear calibration ranges were 1.1 × 10⁻⁶–6.0 × 10⁻⁴ mol l⁻¹ for 2,4-dinitrophenol and 7.0 × 10⁻⁷–6.0 × 10⁻⁴ mol l⁻¹ for 2,5-dinitrophenol, with detection limits of 2.7 × 10⁻⁷ and 1.1 × 10⁻⁷ mol l-1 respectively. This method has been applied to the detection of dinitrophenols in simulation water sample, and the recovery was from 96.7 to 102.5%.     

Detection limits of Au using fast and thermal neutron activation analyses

The applicability of fast and thermal neutron activation analyses for the determination of gold in rock samples has been studied. Using a Ge/Li/ detector limit of 0.45 mg g⁻¹ was obtained for a fast neutron flux of 8.10⁷ n cm⁻².s⁻¹. With a thermal neutron flux of 6.10⁵ n cm⁻².s⁻¹ and the same detector a value of 35 μg g⁻¹ was obtained. Using a NaI/Tl/ crystal a sensitivity of 14 μg g⁻¹ was attained at the same thermal flux. This work was supported in part by the Hungarian Academy of Sciences.     

The electrochemical properties of dopamine,epinephrine and their simultaneous determination at a poly(L-methionine) modified electrode

A poly(L-methionine) modified electrode, fabricated by electrochemical immobilization of the L-methionine on a glassy carbon electrode, was used for simultaneous determination of dopamine and epinephrine through cyclic voltammetry. The electrochemical properties of dopamine and epinephrine have been investigated. This sensor gave two separated cathodic peaks at −0.282 and 0.112 V for EP and DA, respectively. A linear response was obtained in the range of 5.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol l⁻¹ for epinephrine, and 1.0 × 10⁻⁶ to 5.0 × 10⁻⁴ mol l⁻¹ for dopamine. The detection limits were 3.6 × 10⁻⁷ mol l⁻¹ and 4.2 × 10⁻⁷ mol l⁻¹ for epinephrine and dopamine, respectively. This method was successfully applied for simultaneous determination of dopamine and epinephrine in human urines. The text was submitted by the authors in English.     

The determination of uranium in biological materials by neutron activation analysis using the fission product134I

A method for the determination of uranium based on²³⁵U thermal neutron fission, has been developed and employed on samples of ashed fish tissue and seaweed. The method involves a post-irradiation ion exchange separation of iodine isotopes. The 884 keV photopeak of¹³⁴I is used for measurement. Uranium detection limits in the samples concerned have been estimated to be 1·10⁻⁸g in terms of natural uranium. The precision achieved in analysing several series of 3–5 samples was 4–10 per cent. The accuracy of the method was tested by employing an independent neutron activation procedure based on²³⁹U measurement. The accuracy of both methods was checked by analysing NBS SRM 1571 ‘Orchard Leaves’.     

Photochemical degradation of typical halogenated herbicide 2,4-D in drinking water with UV/H<Subscript>2</Subscript>O<Subscript>2</Subscript>/micro-aeration

UV/H₂O₂/micro-aeration is a newly developed process based on UV/H₂O₂. Halogenated pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) photochemical degradation in aqueous solution was studied under various solution conditions. The UV intensity, initial 2,4-D concentrations and solution temperature varied from 183.6 to 1048.7 μW·cm⁻², from 59.2 to 300.0 μg·L⁻¹ and from 15 to 30°C, respectively. The concentration of hydrogen peroxide (H₂O₂) and pH ranged from 0 to 50 mg·L⁻¹ and 5 to 9, and different water quality solutions (tap water, distilled water and deionized water) were examined in this study. With initial concentration of about 100 μg·L⁻¹, more than 95.6% of 2,4-D can be removed in 90 min at intensity of UV radiation of 843.9 μW·cm⁻², H₂O₂ dosage of 20 mg·L⁻¹, pH 7 and room temperature. The removal efficiency of 2,4-D by UV/H₂O₂/micro-aeration process is better than UV/H₂O₂ process. The photodecomposition of 2,4-D in aqueous solution follows pseudo-first-order kinetics. 2,4-D is greatly affected by UV irradation intensity, H₂O₂ dosage, initial 2,4-D concentration and water quality solutions, but it appears to be slightly influenced by pH and temperature. There is a linear relationship between rate constant k and UV intensity and initial H₂O₂ concentration, which indicates that higher removal capacity can be achieved by the improvement of these factors. Finally, a preliminary cost analysis reveals that UV/H₂O₂/micro-aeration process is more cost-effective than the UV/H₂O₂ process in the removal of 2,4-D from drinking water.     

The determination of bromine and iodine in environmental water samples by thermal neutron activation and isotope exchange

A routine-method for the determination of bromine and iodine in environmental water by neutron activation is presented. The elements are isolated by isotope exchange between the irradiated sample and a solution of Br₂ or I₂ CCl₄. The method is not sensitive to the chemical species in which the halogen is present. The lower limit of the determination is 1.0 μg Br·1⁻¹ and 0.1 μgI·1⁻¹.     

Electrochemical reduction of tartrazine at multi-walled carbon nanotube-modified pyrolytic graphite electrode

Electrochemical reduction of tartrazine on multi-walled carbon nanotube-modied pyrolytic graphite electrode is investigated. A simple, sensitive and inexpensive method for determination of tartrazine in drinks is proposed. The accuracy and reproducibility of the determination method for various known amounts of tartrazine were evaluated. This method was satisfactorily applied for the determination of tartrazine in drinks. The reduction peak currents were proportional to tartrazine concentrations over two intervals in the range from 2.0 to 70.0 mg l⁻¹ and from 70.0 to 230.0 mg l⁻¹, and the detection limit for tartrazine is 0.5 mg l⁻¹.     

A novel electrochemical method for the determination of trinitrophenol

In pH 5.5, 0.1 mol l⁻¹ HAc-NaAc buffer solution, trinitrophenol has been determined quantitatively with differential pulse voltammetry by detecting its reduction peak currents at the glassy carbon electrode. The detection sensitivity was enhanced significantly by the addition of the surfactant of cetyl pyridinium chloride, and the enhancement mechanism was also studied in detail. The linear calibration range was 8.0 × 10⁻⁷ to 2.0 × 10⁻⁴ mol l⁻¹, and the detection limit was established to be 1.9 × 10⁻⁷ mol l⁻¹. This method has been applied to the determination of trinitrophenol in water sample, and the recovery was from 97.6 to 103.5%.     

Voltammetric determination of ciprofloxacin based on the enhancement effect of cetyltrimethylammonium bromide (CTAB) at carbon paste electrode

Herein, an electrochemical method was developed for the determination of ciprofloxacin based on the enhancement effect of cetyltrimethylammonium bromide (CTAB). In pH 7.0 phosphate buffer, a poorly-defined oxidation peak is observed at carbon paste electrode (CPE) for ciprofloxacin. However, the oxidation peak current remarkably increases in the presence of low concentration of CTAB, suggesting that CTAB exhibits obvious enhancement effect to the determination of ciprofloxacin. All the experimental parameters, such as supporting electrolyte, pH value, concentration of CTAB, and accumulation time, were optimized for ciprofloxacin analysis. This new method possesses high sensitivity (detection limit is 5.0 × 10⁻⁸ mol l⁻¹), wide linearity (1.0 × 10⁻⁷−2.0 × 10⁻⁵ mol l⁻¹), rapid response, low cost and simplicity. Finally, this method was successfully employed to detect ciprofloxacin in drugs. The text was submitted by the authors in English.     

Applications of gamma-spectrometry in determining chlorine in aqueous solutions

A method is described for the radioanalytical determination of traces of chlorine in aqueous solutions without radiochemical separation or purification. Using a gamma-spectrometer with monocrystal scintillator, the sensitivity of the analysis is about 1·10⁻⁸ g of chlorine/ml, the time of analysis being 15 minutes. For the selective determination of chlorine in aqueous solutions containing a large amount of impurities, a bicrystal scintillation sum-coincidence spectrometer was employed with 120×100 mm NaI(Tl) crystals and thus the³⁸Cl cascade radiation could be used. Application of the sum-coincidence spectrometer allowed a reliable determination of 1·10⁻⁷ g of Cl/ml against a background of 1·10⁻⁵ g of Na/ml.     

Molecularly imprinted solid-phase extraction and flow-injection chemiluminescence for trace analysis of 2,4-dichlorophenol in water samples

Highly sensitive flow-injection chemiluminescence (CL) combined with molecularly imprinted solid-phase extraction (MISPE) has been used for determination of 2,4-dichlorophenol (2,4-DCP) in water samples. The molecularly imprinted polymer (MIP) for 2,4-DCP was prepared by non-covalent molecular imprinting methods, using 4-vinylpyridine (4-VP) and ethylene glycol dimethacrylate (EGDMA) as the monomer and cross-linker, respectively. 2,4-DCP could be selectively adsorbed by the MIP and the adsorbed 2,4-DCP was determined by its enhancing effect on the weak chemiluminescence reaction between potassium permanganate and luminol. The enhanced CL intensity was linear in the range from 1 × 10⁻⁷ to 2 × 10⁻⁵g mL⁻¹. The LOD (S/N = 3) was 1.8 × 10⁻⁸g mL⁻¹, and the relative standard deviation (RSD) was 3.0% (n = 11) for 1.4 × 10⁻⁶g mL⁻¹. The proposed method had been successfully applied to the determination of 2,4-DCP in river water. Figure Effect of 4-VP content on the ultraviolet spectrum of 2,4-DCP in chloroform     

The determination of vanadium in sea and surface waters

A simple and sensitive method for the determination of vanadium in sea and surface water is presented. The method is based on preconcentration of vanadium on active charcoal at a pH 3.6±0.2, followed by instrumental neutron activation analysis of the charcoal adsorbers and measurement of⁵²V (T=3.71 m). The limit of the determination, which is set by the blank value of the charcoal, is 0.01 μg V·1⁻¹. Data are given for Dutch sea and surface water.     

Determination of nitrogen,oxigen, fluorine,phosphorus, sulfur and chlorine in aluminium alloys by means of neutron activation

N, O, F, P, S, Cl can be mixed with aluminium during electrolysis, alloying operations and surface treatments. These elements allow changes in mechanical properties. We have adapted separation methods to neutron activation analysis of aluminium alloys down to the sub—ppm level. N, F, Cl, determinations need distillation. S and P separations are based on liquid extraction. O determination is carried out by instrumental method. Tracers and inactive carriers are used for separation study. Clearning of the surface is performed if necessary. 14 MeV neutron activation is applied to nitrogen, oxygen and fluorine determination. The sensitivity is about 200 imp/min/mg. Reactor neutron activation is performed for phosphorus, sulfur and chlorine analysis. The detection level is 0.1 μg/g. Interesting differences of N, O, F, and Cl contents are observed for Al−Zn or Al−Cu alloys in the range 0.1–10 μg/g.     

Determination of silver traces in air by neutron activation analysis

A non-destructive system for determination of silver traces in air particulates collected on cellulose filters is described, based on neutron activation followed by¹¹⁰Ag β⁻ counting instead of the 657.7 keV γ-ray. The determination limit (for 10% confidence limit) is estimated to be about 10⁻⁹ g. The method is easily applicable to the determination of silver in cloud seeding experiments, since the filters themselves provide a consistent and fairly uniform source and samples are collected in general far from industrial areas, where the concentration of possible interfering elements in air is reasonably low.