24 research outputs found
GeoloÅ”ki, morfoloÅ”ki i pedoloÅ”ki Äinioci teorara Smederevke
Terroir depicts a set of pedologic, microāclimatic and historical factors that have a say in deciding whether and where to practice viticulture and determines its qualitative and quantitative exploitation potential. For winemakers, it is paramount for targeting a viticulture variety. European winemakers use to guide their choices by the family tradition. Scientific breakthroughs, i.e. pedological characterization of the soil, introduced a new approach for viticulture, and drove the worldāleading wineries to turn to scientific approach in the last 30 years. In this research, we went one step further in respect to pedological approach. Since the soil itself is considered as a product of its bedrock and climate, it is logical to also include those factors that condition the properties of the soil itself in the terroir context, such as geological and morphologic factors (Burns, 2010). It is thereby, possible to perform a preliminary delineation of zones with suitable set of factors at regional scales, and direct the subsequent, more detailed soil investigations. By analyzing wider areas, it becomes possible to plan more strategically, especially when it comes to preservation of rare and indigenous vine varieties. From winemakersā perspective, indigenous vine varieties represent the true genetic potential. Smederevka, which is shyly reāintroduced, but without any planning and consulting the profession is one such example. Before the 2nd World War, Smederevka (colloquially known as āthe Yellowā) was grown predominantly in the Smederevo wine region, but with caution to the microālocation, soil composition, slope aspect, sun reflection off the water surface, etc. The quality was unparalleled in comparison to the same vine from 1950ā1990, a period marked by a highāyield, collective farming practice of the āGodominā company back in the socialism. Locality Plavinac in Smederevo (from experience) has the Smederevka vine with the best sensory characteristics, although microālocalities Zlatno Brdo (Mons Aureus) and Petrijevo are more familiar
Some aspects of health impairment in workers from an epoxy resin (araldit) plant with regard to hygienic conditions
U ovom radu data je analiza higijenskih uslova, posebno zapraÅ”enost vazduha i hemijskih profesionalnih Å”tetnosti u Odjeljenju araldita. ZapraÅ”enost vazduha (kvarcnom praÅ”inom i praÅ”inom staklenog vlakna) prelazila je MDK, a meÄu hemijskim Å”tetnostima posebno se istiÄe anhidrid ftalne kiseline koji takoÄe premaÅ”uje MDK. Predloženo je da MDK za praÅ”inu staklenog vlakna iznosi 3 mg/m3. Ispitivanjem zdravstvenog stanja 72 radnika Odjeljenja araldita naÄene su hroniÄne upalne promjene na gornjim disajnim putevima. Pored toga ustanovljena su 2 sluÄaja punktiformne pneumokonioze, 1 sluÄaj punktiformne pneumokonioze udružene sa inaktivnom tuberkulozom pluÄa, 5 sluÄajeva inaktivne tuberkuloze pluÄa i visok procenat lakih opstruktivnih smetnji (27,1%). Predložene su neke zaÅ”titne mjere koje se odnose na tehniÄku i medicinsku prevenciju.Hygienic conditions in an araldit plant were analyzed with particular regard to the concentration of dust and noxious chemical substances in the air. Dust level in the air (quartz dust and fiber glass dust) and among chemical noxious agents that of phthalic anhydride exceeded maximum permissible concentrations. It is proposed that maximum permissible concentration for the fiber glass dust be 3 mg/m3. A medical examination of 72 workers employed in the plant revealed chronic inflammatory changes in the upper respiratory airways. Besides, two cases of punctiform pneumoconiosis were found, one of them connected with inactive tuberculosis of lungs, then five cases of inactive tuberculosis of lungs and a high percentage of mild obstructive disturbances (27.1%). Several protective measures concerning technical and medical prevention are recommended
Computational studies in the AlPO4-34 system
The lattice energies of the as-synthesized fluoride-containing chabazite-like aluminophosphate (AlPO4-34F) and of the corresponding metal-substituted materials [MeAPO-34F, Me = Mn(II), Co(II), Ni(II)] have been calculated in order to investigate the Al-site preference the transition metal substitution in the AlPO4-34F. The calculations show that the transition metal ions in MeAPO-34F should preferentially occupy octahedral Al3+ sites, and kinetic reasons are suggested as an explanation for the actual preference of tetrahedral sites. The lattice energies have also been calculated for the calcined AlPO4-34F material (AlPO4-34) and the rehydrated-calcined product (AlPO4-34h). The AlPO4-34 is found to be less stable than either AlPO4-34F or AlPO4-34h, which is consistent with the fact that AlPO4-34 can only be prepared starting from AlPO4-34F
Thermal investigation of some chelate Ni(II) complexes
Several diamine-nickel(II) complexes have been prepared and the kinetic parameters of their decomposition reactions investigated. The complexes undergo a gradual thermal decomposition. First, water is lost, followed by the departure of the diamine ligands. The activation energies for the first deamination decrease in the order Ni(1,2-pd)(3)Cl-2(H2O)(2) = Ni(en)(3)Cl-2(H2O)(2) gt Ni(1,3 -pd)(3)Cl-2(H2O)(2) gt Ni(dieten)(2)Cl-2 (H2O)(2) (en = 1,2-diaminoethane; 1,2-pd = 1,2-diaminopropane; 1,3-pd = 1,3-diaminopropane; dieten = 2-diethylaminoethylamine) which is in accordance with the chelate effect. The decomposition of the complexes can be represented by a variety of solid state decomposition models depending on the particular complex, as well as on the stage of the decomposition
Isomorphous element substitution in the chabazite-like aluminophosphate framework
Thermal investigations and Fenske-Hall SCF MO calculations have been used for studying isomorphous element substitution in the chabazite-like aluminophosphate framework prepared in the presence of tetraethylammonium hydroxide as a template. The thermal measurements show that the temperature at which the template removal occurs increases as the element varies in the Si-Zn-Mn-Co series. The Fenske-Hall SCF MO calculations on model segments of the framework indicate that the trend can be related to an appropriate decrease in basicity of the oxygen atom directly bound to the element
On the thermal decompositions of the trivalent trioxalato complexes of Al, Cr, Mn, Fe and Co
The thermal decompositions of the complexes K-3[M(ox)(3)]. 3H(2)O (M=Al, Cr, Mn, Fe, Co; ox=C2O42-) were studied. Dehydration of the complexes occurs up to 200 degreesC, this being a three-step process for M=Al, Cr, Mn and Co, and a two-step process for M=Fe. Decomposition of the dehydrated complexes proceeds in several steps. For M=Al, Cr and Fe, the decomposition takes place with the evolution of CO, whereas for M=Mn and Co the decomposition of the oxalate ligand yields solid C besides CO. The temperature of CO liberation decreases in the series Cr lt Al lt Co lt Mn lt Fe. For M=transition metal, this trend can be explained by the fact that the strength of the C-C bond in the oxalate ligand decreases in the series Cr lt Co lt Mn lt Fe
The structure directing role of 1,3-diaminopropane in the hydrothermal synthesis of iron(III) phosphate
13-Diaminopropane (DAP) was used as a structure-directing agent for the hydrothermal synthesis of an organically templated iron phosphate. During crystallization at 180 degreesC, iron phosphate (FePO-DAP) with a layered structure was formed after one day. Longer crystallization yielded a mixture of FePO-DAP and leucophosphite, raising the question whether a transformation of FePO-DAP to leucophosphite occurs. or wheter DAP decomposes under hydrothermal conditions resulting in leucophosphite formation. Lattice energy, and free energy calculations strongly support the supposition that a decomposition of DAP occurs prior to the formation of leueophosphite
A kinetic study of the thermal degradation of cetyltrimethylammonium bromide inside the mesoporous SBA-3 molecular sieve
Thermal degradation of cetyltrimethylarnmonium bromide (CTMAB) inside the mesoporous SBA-3 has been studied under non-isothermal conditions. There are two distinct although partly overlapping kinetic processes, and both of them can be described by the Sestak-Berggren model. The main decomposition step proceeds with Ea = 116Ā±2 kJ/mol which is significantly lower than for the mesoporous MCM-41 and MCM-48 suggesting that the interaction between CTMAB and the silica network plays a crucial role in the removal of the surfactant from the as-synthesized material. The second decomposition step has a higher Ea value (Ea = 153Ā±5 kJ/mol) than the first step, indicating that it is primarily controlled by the size of the pore openings
The possibility of separating hydrogen fluoride from its gaseous mixture with silicon tetrafluoride
We report in this paper investigations of the conditions necessary to effect the selective absorption of hydrogen fluoride from its gaseous mixture with silicon tetrafluoride when that mixture is brought into contact with solid sodium fluoride. Thus, when an anhydrous HF-SiF4 gas mixture is brought into contact with granular NaF at room temperature only hydrogen fluoride is absorbed (giving NaFā¢HF), while silicon tetrafluoride remains in the gaseous state. In this way it is possible to separate HF from SiF4. The hydrogen fluoride may subsequently be regenerated by heating the sodium hydrogen fluoride at 350-400Ā°1. If, however, the gaseous mixture contains only small traces of water vapor then SiF4 also reacts with NaF to give Na2SiF6 in addition to NaFā¢HF. Under these circumstances it is not possible to effect a separation