Modeling of kinetics of pertechnetate removal by amino-functionalized glycidyl methacrylate copolymer

Technetium-99 comprises a significant health risk, since edible plants can bioaccumulate and convert it to more lipophilic species that cannot be excreted through urine. Batch kinetics of pertechnetate removal from aqueous solutions by two samples of crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) functionalized with diethylene triamine (PGME-deta) was investigated at the optimum pH value of 3.0, and the initial solution activity of 325 MBq dm⁻³. PGME-deta was characterized by elemental analysis, mercury intrusion porosimetry, and scanning electron microscopy. Five kinetic models (pseudo-first, pseudo-second order, Elovich, Bangham, and intraparticle diffusion) were used to determine the best-fit equation for pertechnetate sorption. After 24 h, PGME-deta samples sorbed more than 98% of pertechnetate present, with maximum sorption capacity of 25.5 MBq g⁻¹, showing good potential for remediation of slightly contaminated groundwater.     

Investigation of the combined effect of argon addition and substrate bias on the growth of ultrananocrystalline diamond layers

In our recent project the combined effect of argon addition and substrate bias was investigated in the microwave plasma assisted chemical vapor deposition of diamond, focused on the ultrananocrystalline phase. Over the conventional qualifying techniques, i.e., Raman and SEM studies, we have led a special in-situ mass spectrometry investigation to explore the growth mechanism of UNCD, analysing the gas composition close to the surface. To achieve this aim, ion beam mass spectrometry (IBMS) was used for in-situ, real time, mass-selective analysis of the incoming species playing an important role in the MWPECVD (Microwave Plasma Enhanced Chemical Vapor Deposition) of the ultrananocrystalline diamond. In our experiments Ar, CH₄, and H₂ gases were used as source gases in a wide range of concentrations applying different values of substrate bias to deposit different phases of diamond. By the IBMS technique we can measure the fluxes of different species: C_xH_y (x = 1–2, y = 0–2) during the phases of deposition, either under the conditions of microcrystalline diamond (MCD), nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD) synthesis. As a result of it, we can compare the different mechanisms of layer formation: i.e.: whether C₁ species or C₂ mediated growth method takes place, or probably both C₁ and C₂ species propagate the diamond lattice. Based on the given tendency by comparing the IBMS data (i.e.: fluxes of surface species) with the growth rate, morphology, and Raman spectra of the layers we propose, that in the case of UNCD a similar (but not exactly the same) growth mechanism can be found as in the case of MCD i.e.: C₁ species are the most likely precursors.     

Design and test of a large-area scintillation detector for fast neutrons

A plastic scintillator array of 3.4 m² total area for the detection of neutrons in medium-energy nucleon–nucleon reactions was constructed and built. Calibration procedures for the detector were developed which allow the monitoring of gain shifts by means of muons from the cosmic radiation. Experiments were performed in order to calibrate the efficiency simulations and study the performance of the detector using the d+t→+n reaction at 14.7 MeV neutron energy and proton-induced deuteron breakup at 300 MeV.     

Improvement of wood properties by impregnation with macromonomeric initiators (macroinimers)

Scotch pine, eastern spruce, and eastern beech samples sawed longitudinally were impregnated with a new type of polymerization mixture (macroinimer and styrene), leading to crosslinked block copolymers of styrene and poly(ethylene glycol). Weight gains of 36.37–91.13% were obtained after polymerization for 2 h. Water uptake of the polymerized wood was found to be 35.13–72.07% after a water soak test of 144 h. While spruce gave the highest uptake (72.07%), beech showed the lowest value (35.13%). The specimens impregnated with the mixture of macroinimer and styrene showed a water-repellent effectiveness of 35.14–58.15% after a water soaking test of 144 h. The highest values of water-repellent effectiveness were found for spruce, while the lowest values were obtained for pine. A maximum antiswell efficiency (ASE) of 42.43% was obtained for spruce, followed in order by beech and pine, respectively. The ASE value increases with an increase in wt % gain. Improvements of 19.12% in longitudinal compression and 25% in bending strength were also achieved for spruce samples with low weight percent gain. IR spectroscopy was used for chemical characterization of the wood–polymer composite. © 1993 John Wiley & Sons, Inc.     

Associations between Oil Yield and Profile of Fatty Acids,Sterols, Squalene,Carotenoids, and Tocopherols in Seed Oil of Selected Japanese Quince Genotypes during Fruit Development

Tocopherols, phytosterols, carotenoids, and squalene are present in mature seeds of Japanese quince. Yet, little is known about the relationship between these compounds and oil yield during fruit and seed development. The profile change of lipophilic compounds during fruit and seed development in Japanese quince cultivars “Darius,” “Rondo,” and “Rasa” is investigated. It is shown here that during fruit and seed development, there is a significant reduction, three‐ to over tenfold, in the concentration of minor bioactive compounds in seed oil. It is recorded that delay between synthesis of tocopherols and oil in Japanese quince seeds during the fruit development results in a logarithmic relationship between the oil content and tocopherols concentration in the seed oil (R² = 0.980). Similar trends are observed between oil yield and phytosterols, and carotenoids (R² = 0.927 and R² = 0.959, respectively). The profile of fatty acids during the development of the seeds significantly is changed. The reduction of linoleic, palmitic, and gondoic acids levels and increment of oleic acid is noted. The oil content, profile of fatty acids, and concentration of bioactive compounds in all three genotypes of Japanese quince do not change significantly statistically during the last month of fruit development. Practical Applications: Some fruits are harvested at different degrees of maturity mainly due to a logistic issue and uneven ripening of fruits, which affects the chemical composition of whole fruit including seeds. Therefore, it would be good to know how the chemical composition is changing in plant material during development especially in the last month before harvest. Production of Japanese quince continues to rise year to year and with it the volume of generated by‐products such as seeds. This study demonstrates how it changes the oil content, profile of fatty acid, and concentration of tocopherols, squalene, phytosterols, and carotenoids in the seeds and seed oil of three Japanese quince cultivars “Rondo,” “Darius,” and “Rasa” during plant development. The provided information can be very useful for the manufactories oriented on the processing of by‐products, mainly seeds, generated by other branches of industry, for instance, fruit‐processing.     

Effect of feed restriction on metabolites in cerebrospinal fluid and plasma of dairy cows

Endocrines and metabolites in the circulation act as long-term hunger or satiety signals in the brain during negative energy balance and play an important role in the control of feed intake. These signals also occur in the cerebrospinal fluid (CSF), which surrounds the hypothalamus and brainstem: 2 major centers of feed intake regulation. Thus CSF functions as a transport medium for fuel signals between blood and brain. The CSF metabolite concentrations are mainly under control of the blood-brain barriers, which provide specific carrier molecules facilitating the entry of substances required by the brain and protect the brain from factors that could impair neuronal function. The transport of small molecules such as amino acids (AA) across the blood-brain barriers may be limited by competing AA that share a common transporter for the uptake into brain. Consequently, CSF metabolite concentrations differ from those in blood. Thus it appears likely that central (CSF) rather than peripheral (blood) metabolites act as pivotal signals for the control of feed intake. However, the contribution of putative orexigenic and anorexigenic signals in CSF of cows has not been studied so far. Therefore, the aim of this study was to elucidate associations existing between both plasma and CSF metabolites, each in response to feed restriction-induced negative energy balance. Seven German Holstein dairy cows, between 87 and 96 DIM of the second lactation (milk yield, 27.9 L/d) were fed ad libitum (AL) for 4 d and CSF from the spinal cord and blood from the jugular vein was withdrawn before morning feeding at the fifth day. Subsequently, animals were feed restricted (R) to 50% of the previous AL intake for 4 d and CSF and plasma were collected at the ninth day. Body weight, feed intake, water intake, and milk production were determined. Thirty-one AA, β-hydroxybutyric acid, cholesterol, glucose, lactate, nonesterified fatty acids, urea, and osmolality were measured in both CSF and plasma, whereas free fatty acids and volatile fatty acids were determined in plasma only. Although plasma arginine (132%), leucine (134%), lysine (117%), nonesterified fatty acids (224%), and cholesterol (112%) increased, tryptophan and carnosine decreased (-33% and -20%, respectively) in R animals as compared with AL animals. In CSF, concentrations of these metabolites were not affected after R feeding, suggesting that these identified plasma metabolites have only little potential to contribute to central feed intake regulatory signaling in cows. By contrast, in CSF, serine, threonine, and tyrosine decreased (-20, -24, and -31%, respectively) after R feeding. Therefore, these 3 AA are potential centrally acting anorexigenic signals in cows.     

Composition of the Defensive Secretion in Three Species of European Millipedes

Three European julid species, Cylindroiulus boleti, Leptoiulus trilineatus, and Megaphyllum bosniense, secrete mixtures of up to 12 different quinones. The major components in these species are 2-methoxy-3-methyl-1,4-benzoquinone and 2-methyl-1,4-benzoquinone. 2-Methoxy-5-methylhydroquinone is detected for the first time in the Class Diplopoda. 2-Hydroxy-3-methyl-1,4-benzoquinone, 2,3-dimethoxyhydroquinone, 2-methyl-3,4-methylendioxyphenol, and 2,3-dimethoxy-5-methylhydroquinone are registered for the first time in representatives of the family Julidae. The similar chemical composition of defense secretions in all analyzed European julids and Pacific spirobolids supports the idea of the chemical consistency of defensive compounds in juliform millipedes.