U radu su predstavljeni rezultati terenskog istraživanja na uzorku predstavnika službi za potporu poljoprivredi na području Jadranske Hrvatske. Predstavnici su službe na nacionalnoj i regionalni ...razini, udruge i znanstvena zajednica. Cilj je bio istražiti mišljenja predstavnika o općoj promjeni klime i njihov stav prema utjecaju i posljedicama klimatskih promjena, te provjeriti postojanje signifikantnih razlika prema lokaciji i tipu službe. Predstavnici se uglavnom slažu s izjavama o općoj promjeni klime i izjavama o utjecaju i posljedicama klimatskih promjena. Utvrđeno je nekoliko značajnih razlika u mišljenju i stavu predstavnika službi s obzirom na lokaciju. Prema dobivenim rezultatima predlaže se daljnja edukacija predstavnika službi za potporu poljoprivredi.
Cilj rada je ocijeniti povjerenje poljoprivrednika u stručne službe i izvore informacija nužnih u prilagodbi i ublažavanju posljedica klimatskih promjena. U radu se dodatno ocijenio utjecaj ...sociodemografskih obilježja i obilježja gospodarstva na povjerenje poljoprivrednika prema određenim službama i izvorima informacija. Rezultati pokazuju kako poljoprivrednici imaju najveće povjerenje u ostale poljoprivrednike, obrazovne i znanstvene institucije i specijalizirane poljoprivredne trgovine. Razina obrazovanja ispitanika, lokacija gospodarstva, završeno obrazovanje u području poljoprivrede, udio poljoprivrede u prihodima i godine bavljenja poljoprivredom pokazale su se značajnim s obzirom na povjerenje u pojedine službe i izvore informacija.
Electrostatic potential at the inner plane of the hematite aqueous interface, i.e., surface potential, was measured by means of a single-crystal hematite electrode. Acidic solutions were titrated ...with base and then back-titrated with acid. Surface potentials were evaluated from electrode potentials by setting the zero value at the isoelectric point. In the case of fast titrations the equilibration time was approximately 10 min, and significant hysteresis was obtained, more pronounced at higher electrolyte concentrations. Hysteresis disappeared in slow titration runs when the equilibration time was extended up to 120 min, and also when ultrasound was applied. Hysteresis was observed in the pH region close to neutrality, where the concentrations of potential-determining H
+ and OH
− ions are low. Equilibration was fast in acidic and basic regions. These results are explained on the basis of the kinetics of surface reactions, supported by the following rate of single-crystal electrode equilibration. It is concluded that the equilibration rate at the interface is specific for a given system and is not a general phenomenon. As several systems may undergo fast equilibration, such data may be regarded as equilibrium data and interpreted by the surface complexation model. In other cases, one should perform kinetic tests and apply extended equilibration times.
Surface potential at hematite aqueous interface was measured with a single-crystal electrode. Hysteresis was obtained in the acid–base titrations curves and disappeared in extremely slow titration runs.
Standard states and equilibrium in ionic micellar systems Kallay, Nikola; Glušac, Tomislav; Preočanin, Tajana ...
Colloids and surfaces. A, Physicochemical and engineering aspects,
09/2009, Letnik:
347, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
A theoretical treatment of ionic micelle formation based on the Mass Action Law (
i.e. on the Molecular Concept) is presented. In the expression for the thermodynamic equilibrium constant micelles ...were considered as molecular entities. Therefore, the activities,
i.e. the concentrations and activity coefficients, of all the interacting solute species, including the micellar molecules, were introduced. The standard state of the charged micellar molecules was taken to correspond to that of ions dissolved in a hypothetical solution containing one mole per litre of entities at the ideal condition of zero ionic strength. Experimental approach to the ideal state was not feasible, because extrapolation to infinite dilution would have changed the composition of micellar species (aggregation and association numbers) and would even have led to their disappearance below the critical micellization concentration. The application of the Debye–Hückel and Gouy–Chapman theories for evaluation of the activity coefficients of ionic micellar species was discussed. The equilibrium of micelle formation was examined in dodecyltrimethylammoniumbromide, cetyltrimethylammoniumbromide, and sodiumdodecylsulphate solutions.
Equilibrium at the solid-liquid interface is the subject of numerous experimental and theoretical investigations. Several different models describing the structure of the electrical interfacial layer ...(EIL) and the mechanism of surface reactions are suggested in the literature. At present it seems impossible to decide which of them describe the real situation best. One of the routes towards the solution of this problem is the development of new experimental methods and simultaneous interpretation of different sets of data (e.g., adsorption data, Y0 data, s0 data, z-potential data, etc.). Interpretation based on such an approach may eventually enable differentiation between models and a better choice of appropriate ones. Another route is to refine or develop a new, more realistic and less approximate, theoretical concept. This article presents a review of such efforts (EIL structure, electroneutrality condition, surface potential measurements, capacitors within EIL, enthalpy of surface reactions, colloid stability, etc.), with special emphasis on the role of Nikola Kallay in this field, to whom this article is dedicated on the occasion of his 65th birthday.
