Authors:K. V. Kocheva, G. I. Georgiev, V. K. Kochev, K. Olšovská, and M. Brestič
The potentials of an electrochemical and a physical technique for detection of physiological differences in three wheat cultivars under optimal growth conditions were outlined in the study. Electrolyte leakage kinetics was established by continuous measurements of conductivity of solutions in which leaf pieces were incubated for 24 hours. Impedance spectra were obtained from intact leaves at frequency range from 7 to 2010 Hz and 250 mV measuring voltage applied between two gold plated silicon substrates serving as electrodes. The obtained spectra were approximated by a model employing two ARC elements connected in series. Parameters of the previously described diffusion model based on time course conductivity measurements were inversely correlated with electrical impedance spectroscopy data, thus the genotype with highest ion leakage (cultivar Prelom) exhibited lowest impedance magnitude. It was concluded that the two methods were able not merely to distinguish the three studied cultivars but also to rank them in the same order based on their electrical properties.
Based on continuous measurements of the atmospheric electric potential gradient (PG) in the Geophysical Observatory at Nagycenk (Hungary), selected data of the interval 1993-2003 have been analysed. The analyses were particularly aimed at the confirmation of global signatures found by a previous study using PG data of a shorter period. The present results have proved that the seasonal variation of PG (generally showing a winter maximum and a summer minimum at land stations) might really be modified at Nagycenk by a secondary maximum appearing in summer-time of certain years. Further analyses have also been carried out by using data derived from measurements with two different apparatus, however, covering a shorter period. Moreover, a connection between the occasional summer peaks of PG and the occurrences of warm El Niño periods might also be suggested on the basis of results derived from selected PG data and appropriate MEI Indices showing the time history of the ENSO phenomenon for the interval 1993-2003.
Theoretical and experimental analysis of the diaphragm diffusion method for study of the state of trace elements in aqueous
solutions is presented. It is shown that the method has substantial advantages over other diffusion methods and over conventional
use of dialysis, particularly when nucleopore or other membranes with small internal surface area are employed. These advantages
include rather short experimental time, not exceeding tens of minutes, lower adsorption losses and lower shift of equilibria
among various forms of the trace element studied. A new method for the continuous measurement of and for the evaluation of
diffusion is suggested, which enables calculation of the abundance of colloidal forms of the element. Verification of the
method is carried out for a particular case using trace radiocerium.
Theoretical and experimental analysis of the open-ended capillary diffusion method for study of the state of trace elements
in aqueous solutions is presented. It is shown by theoretical considerations that the use of the discontinuous capillary method
of diffusion and the evaluation of single measurements using the classical Anderson-Saddington equation yields incorrect diffusion
coefficients if two or more forms of the trace element with significantly different diffusion characteristics are simultaneously
present in the solution. A new method for the evaluation of diffusion is suggested, which enables calculation of the abundance
of two different forms of a trace element. The method employs a continuous measurement of diffusion combined with computer
analysis of the data obtained. Verification of the method is carried out for a particular case using trace radiocerium. The
effect of adsorption on the diffusion measurement and interpretation is discussed.
Authors:Ferenc Ender, Diána Weiser, Botond Nagy, Csaba László Bencze, Csaba Paizs, Péter Pálovics, and László Poppe
Biotransformation of l-phenylalanine (l-1a) and five unnatural substrates (rac-1b–f) by phenylalanine ammonia-lyase (PAL) was investigated in a novel microfluidic device (Magne-Chip) that comprises microliter volume reaction cells filled with PAL-coated magnetic nanoparticles (MNPs). Experiments proved the excellent reproducibility of enzymecatalyzed biotransformation in the chip and the excellent reusability of the enzyme layer during 14 h continuous measurement (>98% over 7 repetitive measurements with l-1a). The platform also enabled fully automatic multiparameter measurements with a single biocatalyst loading of about 1 mg PAL-MNP. Computational fluid dynamics (CFD) calculations were used to study the flow field in the chambers and the effect of unintended bubble formation. Optimal flow rate for l-1a reaction and specific activities for rac-1b–f under these conditions were determined.
Authors:A. Hutter, R. Larsen, H. Maring, and J. Merrill
Continuous measurements of atmospheric222Rn were made for the past three years by the Environmental Measurements Laboratory (EML) at the Atmosphere/Ocean Chemistry Experiment site located at Tudor Hill, Bermuda and at the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory Mauna Loa Observatory. The222Rn analyzer is based on the two-filter tube method. At the Bermuda site, monthly median222Rn concentration range from 50 to 700 mBq m–3, and the concentrations vary seasonally, with a maximum in the winter and a minimum in the summer. The concentrations are significantly elevated when local winds traverse the island. At MLO, monthly median222Rn concentrations range from 100 mBq m–3 during the fall months to 400 mBq m–3 during the spring months. The springtime maximum values correspond to periods of rapid transport in the free troposphere from the Asian continent, corroborated by backward air mass trajectories. The222Rn data are also used to help decipher local daily upslope/downslope conditions present at MLO. This study illustrates the value of atmospheric222Rn monitoring, when screened through the filter of local meteorology, in studying the transport of continental air to the oceans, as well as the dynamics of local meteorological effects.
A very low level temperature derivative apparatus is described. It is able to give a true and continuous measurement of heating or cooling rate from room temperature up to 900° with a detection threshold as low as 30μ°Cs−1. This apparatus can be used for derivative thermal analysis and as slope temperature generator.
There is an increasing need in industry, arising from both economic and environmental considerations, to reduce costs and improve product quality through the use of automation. The use of on-line analysis instrumentation provides plant operators with a means for continuous measurement and rapid response. This can result in better control of process efficiency, product quality and resource utilization, all of which produce significant economic and environmental benefits. On-line measurement of bulk elemental composition is important in many industrial applications and is best achieved with highly penetrating neutron-gamma techniques. This paper presents recent work by CSIRO Minerals on the development and implementation of such a technique, NITA (neutron inelastic-scattering and thermal-capture analysis). NITA is distinct from the more common PGNAA (prompt neutron gamma activation analysis) technique in its use of fast neutron sources to generate inelastic scattering reactions, and in its consequent ability to excite gamma-rays from industrially important elements such as carbon and oxygen. The paper will compare the features of NITA and PGNAA analysers and will discuss applications of NITA in industry, including the on-line analysis of composition in pyrometallurgical applications and the on-conveyor belt monitoring of cement raw meal and coal.
Authors:Marianna Papp, János Balogh, Krisztina Pintér, Szilvia Fóti, Péter Koncz, Marian Pavelka, Eva Darenova, and Zoltán Nagy
Az utóbbi évtizedben zajló kutatások kimutatták, hogy a talajok CO2-kibocsátása jelentős napi és szezonális változékonyságot mutat. A manuális mérőrendszerekkel azonban ez nehezen követhető nyomon. Éppen ezért megjelent az igény a nagyobb időbeli felbontású automata mérőrendszerekre, több gyártó készítette el saját fejlesztésű műszerét. Ezeknek a rendszereknek a hátránya, hogy drágák és többnyire zárt rendszerben működnek, ahol a bonyolult kamranyitó-záró mechanika csökkentheti a működésbiztonságot. További hátrányt jelent a kamrák meglehetősen nagy mérete, ami miatt gyepállományokban nehezen alkalmazhatók.Az általunk kifejlesztett nyílt rendszerű mérőeszköz alkalmasnak bizonyult ezen problémák kiküszöbölésére: a kisméretű kamrák (d = 5 cm) könnyen elhelyezhetők a növények között, nyílt rendszerben nem szükséges kamranyitó-záró mechanikát építeni, és a rendszer olcsón kivitelezhető.A kifejlesztett 10 kamrás mérőrendszer kalibrálását laboratóriumi körülmények között végeztük el, valamint összehasonlítottuk terepi mérések segítségével egy nemzetközileg is hitelesnek számító mérőrendszerrel. A kapott eredmények szerint a kifejlesztett mérőrendszer alkalmas hosszú időtartamú automata-mérésekre, segítségével nagy mennyiségű adat nyerhető.