bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of Rashig rings and the rheological properties of the liquid phase on the pressure drop at the bottom of a reciprocating plate column
Authors: Aleksic Mirko , Veljkovic Vlada , Bankovic-Ilic Ivana , Lazic Miodrag , Skala Dejan
Published: July 2008

The pressure drop at the column bottom, filled with a Newtonian (distilled water) or non-Newtonian (aqueous solution of carboxymethylcellulose, sodium salt, CMC, 1 %) liquid, in the presence of Rashig rings, made of aluminum (0.8 cm in diameter), regularly distributed in the interplate spaces (volume content of the solid phase: up to 3.2 %) was studied. The average and total pressure drop at the column bottom increased with increasing vibration speed and content of the solid particles, but decreased with increasing superficial gas velocity, indepentently of the rheological properties of the liquid phase. The pressure drop at the column bottom filled with the non-Newtonian liquid was found to be higher than that in the case of distilled water.
Effect of fillers on parameters of dry and swollen polymer matrix networks
Authors: Stojceva-Radovanovic Blaga , Markovic Gordana , Marinovic-Cincovic Milena , Babic Dragan , Nedeljkovic Jovan
Published: July 2008

The effect of nano- and micro- particle size of SiO2 on dry and swollen parameter network of the polymer matrix blends of acrylontrile-butadiene (NBR) and chlorosulphonated polyethylene (CSM) such as: volume and mass degree of swelling Rv and Rw; volume fraction of NBR-CSM polymer matrix in swollen gel V2 elasticity modulus G; interaction parameter between NBR-CSM polymer matrix and solvent ? and crossiinking density ?, was tested. The influence of nano-and micro- particle size of SiO2 on physical and mechanical properties, as well as effectiveness volume ratio of filiers in NBR-CSM polymer matrix at 300% elongation was tested using Einstein-Quth-Gold equation. The Kraus equation for swelling test of NBR-CSM polymer matrix containing nano- and micro- particle size of SiO2. Test results have shown that a greater interaction of nano-particie size of SiO2 with NBR-CSM polymer matrix, and possible chemical bonding, than the one of micro-silica was a consequence of a greater contact area. This results in better physical and mechanical properties.
Complexometric determination, Part II: Complexometric determination of Cu2+-ions
Authors: Rajkovic Milos
Published: July 2008

A copper-selective electrode of the coated wire type based on sulphidized copper wire was applied successfully for determining Cu(II) ions by complexometric titration with the disodium salt of EDTA (complexon III). By the formation of internal complex compounds with the Cu(II) ion, the copper concentration in the solution decreases, and all this is followed by a change of potential of the indicator system Cu-DWISE (or Cu-EDWISE)/SCE. At the terminal point of titration, when all the Cu(II) ions are already utilized for the formation of the complex with EDTA, there occurs a steep rise of potential, thus enabling us, through the first or second derivative to note the quantity of copper that is present in the solution. Copper-selective electrode showed a responsivity towards titration with EDTA as a complexing agent, with the absence of "fatigue" due to a great number of repeated measurings. Errors occurring during quantitative measurements were more a characteristic of the overall procedure which involve, because of the impossibility of the complete absence of subjectivity, a constant error, and the reproducibility of the results confirmed this fact. The disodium salt of EDTA appeared as a very efficient titrant in all titrations and with various concentrations ot Cu(II) ions in the solution, with somewhat weaker response at lower concentrations in the solution.
The effect of acrylic resin functionality on the curing process and properties of acrylic-hexamethoxymethylmelamine coatings
Authors: Prendzov Slobodan , Prendzova Magdalena
Published: July 2008

In this paper the effect of the functionality of synthesized thermosetting acrylic resins (with hydroxy and carboxy groups) and the cure temperature on the process of crosslinking and properties of the coatings was investigated. Methylated melamine resin, characterized by 1H and C NMR was used as the crosslinking agent. The degree of crosslinking was studied by infrared spectroscopy by determining the conversion of functional groups and the sol fraction. On the basis of the results obtained it was found that compositions with lower functionality of the acrylic resin had a higher conversion of functional groups, during which cocondensation reactions occurred (acrylic melamine crosslinks) in a wide temperature crosslinking range. Consequently better control of the coating properties was achieved. The degree of crosslinking was in good correlation to the sol fraction content and the resin hardness.
Epoxy coatings electrodeposited on aluminium and modified aluminium surfaces
Authors: Lazarevic Zorica , Miskovic-Stankovic Vesna , Kacarevic-Popovic Zorica , Drazic Dragutin
Published: July 2008

The corrosion behaviour and thermal stability of epoxy coatings electrodeposited on modified aluminum surfaces (anodized, phosphatized and chromatized-phosphatized aluminium) were monitored during exposure to 3% NaCl solution, using electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA). Better protective properties of the epoxy coatings on anodized and chromatized-phosphatized aluminum with respect to the same epoxy coatings on aluminum and phosphatized aluminum were obtained: higher values of Rp and Rct and smaller values of Cc and Cd, from EIS, and a smaller amount of absorbed water inside the coating, from TGA. On the other hand, a somewhat lower thermal stability of these coatings was obtained (smaller values of the ipdt temperature). This behavior can be explained by the less porous structure of epoxy coatings on anodized and chromatized-phosphatized aluminum, caused by a lower rate of H2 evolution and better wet ability.
Influence of both the composition of impregnation solution and impregnation method on copper(II), chromium(VI) and silver(I) deposition on activated carbon
Authors: Ivanovic Slavica , Zivanovic Aleksandar , Bosnjakov Gordana
Published: July 2008

The composition of a solution for impregnating activated carbon (AC) for use in a gas filter was investigated. The solution components were tetraaminocop-per(II) complex, chromium(VI), silver(l) and carbonate ions. Two methods of impregnation were investigated: ion adsorption from aqueous solution in excess and the incipient wetness method. Copper, chromium and silver con-tents on AC Were determined by atomic absorption spectrometry. The largest copper contents (4.38 and 5.00 % (w/w for two AC samples) were achieved at: c([Cu(NH3)4]2+) = 1.0 mol/L; M(Cu) i M(Cr) = 3.75: 1; M(Cu) i M(Ag) = 62: 1 and M(Cu): M(CO3) = 2: 1, using two fold impregnation by the incipient wetness method with 2.4 mL of solution per 3 g AC. The contents of chromium and silver on the same AC samples Were 1.06 and 0.0098 % for the first and 1.14 and 0.009 % for the second AC. A larger Cr content (1.57 %) was achieved from an impregnation solution in excess (c([Cu(NH3)4]2+) = 1.25 mol/L; M(Cu) i M(Cr) = 3: 1; without Ag). The largest Ag content (0.17 %) was obtained using two fold impregnation by the incipient wetness method (c([Cu(NH3)4]2+) = 0.8 mol/L; M(Cu): M(Cr) = 3.75: 1<; M(Cu) i M(Ag) ( 80: 1 and M(Cu) i M(CO3) = 1 i 1.32). Larger metal contents were obtained using two fold impregnation by the incipient wetness method. Further work is needed on the determination of the influence of carbonate ions both on the solution stability and metal deposition on AC.
Determination of platinum in Adam's catalyst
Authors: Andjelic Brankica , Petrovic Nevenka , Jovanovic Milka
Published: July 2008

Adams's catalyst PtO2 x H2O has an important application in the chemical industry. The method for determination of platinum in Adam's catalyst has been elaborated. It includes the combination of cupellation and gravimetry methods. Considering that platinum oxide is practically insolvent in mineral acids, the sample is alloyed with lead by cupellation method and the separated balls solution procedure has been tested. The ball, platinum and lead alloy, is soluble in mineral acid. The platinum was settled by amonium chloride from solution, and obtained deposit treated by amonium acetate with addition of ethanol for lead removing. The retained platinum was determined by atomic absorption spctrophotometry method in the filtrate (after the platinum separation) and the final result of platinum content corrected. It was shown how the combined gravimetric and AAS-Pt determination methods might be used for solving determination of Pt content in practically unsoluble sample of catalyst. Applied procedure enables testing the catalyst quality and proving its characteristics required for chemical industry.
A study of n-alkane type biomarkers in coal
Authors: Milicevic Zoran , Petrovic Milena , Petrovic Petar
Published: July 2008

The isolation of saturated hydrocarbons from free bitumen coal and also from bound bitumen coal in the region of Kosovo is descriled in this study. n-Alkanes from C17-C21 to C33-C35, with A7-C29 being dominant, were identified by gaschromatographic analysis of the free bitumen. This distribution indicated the terrestrial origin of the coals and a low level of carbonification. The decreasing values of the CPI of the bound bitumen (1.08-2.77), composed to the CPI values of the free bitumen (2,04-3,90) and a shift of the dominant n-alkane (A7-C29 -> A7-C23) are a result of the higher "maturity" level of the n-alkanes in bound bitumen.
Detergent zeolite complex "Alusil", Zvornik
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed the basis technological and machine projects for a detergent zeolite complex, on the basis of which a pilot plant with an initial capacity of 5,000 t/y was constructed in 1983 within Birac-Zvornik production complex. Additional projects were done afterwards and the starting capacity increased to 200,000 t/y in 1988. This plant became the biggest producer of detergent zeolite in the world. These projects were manufactured on the basis of specific technology developed in the laboratories of the IGPC.Several goals were realized by designing a detergent zeolite production complex. This technology was an innovation, because a new approach in detergent zeolite production was developed. The product meets all quality demands, as well as environmental regulations. The detergent production process is fully automatized and the product has uniform quality. There is no waste material in detergent zeolite production, because all products with unsatisfactory quality are returned to the process. The production process can be controlled manually, which is necessary during stanrt-up, and repairs.
White filler production plant "Alusil", Zvornik
Authors: Stankovic Mirjana , Pezo Lato , Lazic Nada
Published: July 2008

Experts of the IGPC developed a white filler production technology in the laboratories, and then started production at the "Alusil", Zvornik complex. This plant was constructed in 1987 with a capacity of 20,000 t/y. The product meets all quality demands, as well as environmental regulations. There is no waste material in white fillers production, because all filtrates are kept in closed cycles. Production process is fully automatized, with minimal need for human intervention. The production process can be controlled manually, which is necessary during start - up, and repairs.
Wet hydrate dissolution plant
Authors: Stankovic Mirjana , Kovacevic Branimir , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate dissolution plant. Main goal was increasing the detergent zeolite production capacity. The technological cycle of NaOH was closed, and no effluents emitted, and there is no pollution. Wet hydrate dissolution is now fully continuous, which is important for maintaining zeolite production quality, as well as for simplifying production. The wet hydrate production process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start-up, and repairs. By installing additional process equipment (centrifugal pumps and dissolving reactors) technological bottlenecks were overcome, and by adjusting NaOH tanks and dissolving reactors, the capacities of the process equipment was fully utilized.
Detergent zeolite filtration plant
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed basic projects for detergent zeolite filtration plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with a capacity of 75,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production, from 50,000 to 100,000 t/y. The main goal was to increase the detergent zeolite production capacity. The technological cycle of the filtrate was closed, and no effluents emitted, and there is no pollution. The detergent zeolite filtration process is fully continuous, by which a significant improvement in zeolite production was achieved, both in unification of quality of the product and in simplifying production. This process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start-up, and repairs. By installing additional process equipment (centrifugal pumps, a vacuum system and belt filter) technological bottlenecks were overcome by adjusting the work of centrifugal pumps and belt filter, and also by optimizing the capacities of process equipment.
Increasing the capacity of an evaporation unit
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed a basic technological project for an evaporation unit for detergent zeolite production at "Zeolite Mira", Mira, Italy. The evaporation unit was for a capacity of 15,000 t/h of evaporated water per hour from 26,000 t/h of 11 % NaOH solution.The gained product meets all quality regulation, as well as environmental regulations. The evaporation process is fully automatized, and the product has uniform quality. There is no waste material in detergent zeolite production, because all products with unsatisfactory quality are returned to the process. The production process can be controlled manually, which is necessary during start-up, and repairs. A fully closed cycle of filtrate was achieved by installing an evaporation unit. 11% NaOH solution is produced in detergent zeolite filtration, which is dangerous waste. It is evaporated to 26% NaOH solution and afterwards returned to the wet hydrate dissolution plant. In this way environmental protection is achieved, as well as a highly economical process.
Effects of Rashig rings placed in interplate spaces and the rheological properties of the liquid phase on power consumption in a gassed reciprocating plate column
Authors: Aleksic Mirko , Veljkovic Vlada , Bankovic-Ilic Ivana , Lazic Miodrag , Skala Dejan
Published: July 2008

The power consumption in a gassed reciprocating plate column with Rashig rings placed in interplate spaces increases with both increasing vibration intensity and content of solid particles but decreases with increasing the superficial gas velocity, regardless of the rheological properties of the liquid phase. Under the same operating conditions, the power consumption is higher when the column is filled with a non-newtonian liquid than with distilled water.
Strategic management of technology in phytopharmacy
Authors: Dugalic Sretenka
Published: July 2008

The paper deals with the: 1. Meaning, characteristics and developing possibilities of phytotherapy; 2. Dimensions of markets and technologies in managing phytotherapic assortment. By observing the final results, which were obtained by means of representative sources and other research of phytotherapeutics products, it can be expected applicable to a broader range in practice with input to marketing ideas. The models, presented here, are meant to be innovative applications in the medical marketing concept, by the results of broad spending in the food service industry (domain of dietetics) in the manufacture of food for children, in the manufacture of 'medical cosmetics' and cosmetic-druggist assortments (products for hygiene, shampoos soaps, creams and buble baths).
Conventional and contemporary methods for water treatment: From wastewater to ultra pure water
Authors: Rajakovic Vladana , Rajakovic Ljubinka
Published: July 2008

In this paper modern methods and techniques for water purification are described. Good water quality and the rational use of water are an absolute need of the new millennium. The quality of life depends on water quality. Although it is an ecological priority to prohibit the contamination of water, it is a responsibility for environmental engineers and chemists to develop and apply effective methods for water purification. Beside well-known methods and techniques, it is necessary to create new methods for water purification and treatment. Water recycling is especially important. Plants with membrane separation technologies enable savings in fresh water with high efficiency. Methods for monitoring and controlling processes and water protection should be developed simultaneously with the development of techniques for the methods for purification.
Development of analytical control in the water-steam cycle in thermal power plants
Authors: Rajakovic Ljubinka , Kerecki Jovan
Published: July 2008

In order to maintain high reliability indices in thermal power plants and to realize the expected lifetime of these plants, high water quality should be accomplished. Also, an insight in the working tools of the analyst in thermal power plants and into the types of problems, which help in solving daily tasks, is given. This review considers the implementation of standard control parameters crucial for the indication of water quality in all segments of a water-steam system. A concept of modernization of the system for analytical control and monitoring in the water-steam cycle is suggested.
The influence of fibrous bed bulk density on the bed properties
Authors: Secerov-Sokolovic Radmila , Stanimirovic Olja , Sokolovic Slobodan
Published: July 2008

The mean properties of seven different fibrous materials and the properties of their different bed bulk densities were investigated. The morphology of the surface, size and geometry were measured by optical microscopy. The bed porosity was measured by the weighing method. The experimental bed permeability, in a high range of bulk density, was calculated from the values of the sanitary water pressure drop at a constant temperature of 15?C, since the data followed Darcy's law. The Reynolds number for a fibrous bed was calculated using a relation from the literature. The Reynolds number was less than 1 for all ranges of fluid velocity. Three empirical relations for fibrous bed permeability were used and compared with the experimental data. It was determined that the empirical data depended on the fiber diameter and fraction of solid in the bed. The relative error linearly increased with increasing fiber diameter.
Novel trends in electrocatalysis: Extended Brewer hypo-hyper-d-interionic bonding theory and selective interactive grafting of composite bifunctional electrocatalysts for simultaneous anodic hydrogen
Authors: Neophytides S.G. , Zafeiratos S.H. , Jaksic M.M.
Published: July 2008

Novel Trends in Electrocatalysis: Extended Brewer Hypo-Hyper-d-lnterionic Bonding Theory and Selective Interactive Grafting of Composite Bifunctional Electrocatalysts for Simultaneous Anodic Hydrogen and CO OxidationThe Extended Brewer Interactive Interionic Bonding Theory (EBIIBT) has been developed to show the equivalence of interatomic and interionic bonding features, and for their mutual combinations, as well as its effect upon electrocatalytic properties for the hydrogen electrode reactions (HELR). The equivalence of interionic hypo-hyper-d-interelectronic interaction in both metallic and any other ionic state and its effect upon electrocatalytic properties for hydrogen electrode reactions (HELR) has been proved and inferred. TG (Thermal Gravimetry) analysis of TPR (Temperature Programmed Reduction) of mixed hypc-hyper-d-electronic oxides of transition elements was broadly employed to prove the EBIIBT effect as reflected in dramatically decreased individual temperatures of their mutual reduction into intermetallic phases. The same interionic Brewer (and/or intermetallic) bonding effect has been confirmed both by UPD of hyper-d-upon hypo-d-electronic substrates and vice versa, and by the shift of bonding peaks in XPS analysis.
Development of a new national innovation system
Authors: Domazet Dragan
Published: July 2008

The paper describes a reference model of the national innovation system of Serbia planned to be gradually developed. The model presented is not complete, but is sufficient to illustrate its usage. The development of a national innovation system may be achieved by implementing a phased and segmented approach. This means that parts of the innovation system that are related to specific industrial sectors may be developed separately according to national priorities. Also, the system may be improved and expanded in later phases of its development. The approach suggested is demonstrated in the case of the innovation system of the software industry. The necessary programs and measures for supporting the development of the software industry are listed. Once these programs and measures are implemented, the software industry in Serbia may be able to reach global competitiveness.
The characteristics of novel dosage forms
Authors: Milic-Askrabic Jela , Petrovic Slobodan
Published: July 2008

The objective of pharmaceutical-technological development is to find a procedure of transforming an active substance (a drug) into a drug dosage form which is not only acceptable for application, but also enables the active substance to be released following administration, pursuant to therapy objectives. The aim is that the concentration of the active substance in the action location rapidly reaches a therapeutic level and maintains an approximately constant level in the course of a particular time, according to the established therapeutic goal. The primary objective is to present the active ingredient (drug) in the form and concentration/quantity that enables the corresponding therapeutic response, i.e. to control the site and rate of medicinal substance release from the drug, as well as the rate at which it reaches the membranes and surfaces to which it is absorbed, while applying a common method of administration. The procedures used to achieve this goal are becoming highly complex and demanding and are aiming at sophisticated drug delivery systems and functional packaging material. Development from the existing drug molecule, through the conventional drug dosage form, to a new system of drug "delivery" (novel delivery system), can improve the drug (active substance) characteristics significantly in view of compliance (acceptability by the patient), safety and efficiency. The paper presents an overview of the most important examples of pharmaceutical forms with controlled release and advanced drug "carriers".
Correlation between the structure and biological activity of some coordination compounds of isatin Schiff bases
Authors: Radovanovic Blaga , Konstantinovic Sandra
Published: July 2008

The complexes of Co(ll), Ni(ll), Cu(ll) and Zn(ll) with isatin Schiff bases were synthetised and their structures established by using elemental analysis, as well as by measuring the molar conductivity, AA, FTIR, UV/VIS and 1H NMR and applying TG analysis.Isatin Schiff bases show different antimicrobial activity due to the different nature of the carbonyl and amino components as well as its substituent. The complexes have an enhanced activity compared to the ligands due to the transition metal involved in the coordination. It is also evident that the complexes have different antimicrobial activity, which is related to the nature and typeof coordinated metal.
Enzymes: The possibility of production and applications
Authors: Petronijevic Zivomir
Published: July 2008

Enzymes are biological catalysts with increasing application in the food pharmaceutical, cosmetic, textile and chemical industry. They are also important as reagents in chemical analysis, leather fabrications and as targets for the design of new drugs. Keeping in mind the growing need to replace classical chemical processes by alternative ones, because of ever growing environmental pollution, it is important that enzyme and other biotechnological processes are economical. Therefore, price decrease and stability and enzyme preparation efficiency increase are required more and more. This paper presents a short review of methods for yield increase and the improvement of the quality of enzyme products as commercial products, as well as a review of the possibilities of their application.
The application of disperse systems in environmental engineering
Authors: Povrenovic Dragan
Published: July 2008

This paper presents the experimental results of spouted and spout-fluid bed investigations and their application in waste treatment in the food industry and the fluid-mechanical investigations of a co-current spouted bed with the aim of its application in water treatment, with immobilized microorganism systems. The Investigated systems were applied in animal blood and plasma drying, as a possible ecological solution in the meat-processing industry and brewery yeast drying. These waste materials are very dangerous pollutants for natural recipients. The concept of a co-current spouted bed as a basis for microbiological water treatment in the nitrification process of ammonium nitrogen is presented in the second part of this paper.
Conducting polymer materials
Authors: Jovanovic Slobodan , Nestorovic Gordana , Jeremic Katarina
Published: July 2008

Conducting polymers represent a very interesting group of polymer materials Investigation of the synthesis, structure and properties of these materials has been the subject of considerable research efforts in the last twenty years. A short presentating of newer results obtained by investigating of the synthesis, structure and properties of two basic groups of conducting polymers: a) conducting polymers the conductivity of which is the result of their molecular structure, and b) conducting polymer composites (EPC), is given in this paper. The applications and future development of this group of polymer materials is also discussed.
Immobilization of invertase and glucoamylase on a macroporous copolymer of etyleneglycoldimethacrylate and glycidyl methacrylate and potential applications in biotechnology
Authors: Prodanovic Radivoje , Milosavic Nenad , Jovanovic Slobodan , Vujcic Zoran
Published: July 2008

The optimal conditions for the immobilization of invertase and glucoamylasewere found via their carbohydrate moiety on a macroporous copolymer of ehtyleneglycoldimethacry late and glycidylmethacrylate. Almost all of the added enzyme was bound to the polymer by increasing the time of incubation of the oxidized enzyme with polymer. A specific activity of 5500 U/g for invertase was obtained and 1100 U/g for glucoamylase. The specific productivity for invertase in a packed bed reactor was 3.5 kg/lh and for glucoamylase 1.9 kg/lh. During continuous use in a packed bed the reactor operational half life for invertase was 290 days, while no decrease in activity was observed for glucoamylase. In 50% (v/v) ethanol the immobilized enzymes were five to ten times more stable, and more than 200 times more stable in 25% (v/v) dioxane. The immobilized enzymes retained all activity in petroleum ether after 3 days of incubation. Because of their higher stability over native enzymes, and the large surface area of the polymer immobilized glucoamylase and invertase could be more useful for glycoside synthesis in non-aqueous solvents than native ones.
Study of the catalytic selectivity of an aqueous two-component polyurethane system by ftir spectroscopy
Authors: Stamenkovic Jakov , Cakic Suzana , Nikolic Goran
Published: July 2008

The difficulty in formulating a two component waterborne polyurethane, is the isocyanate-water side reaction, which can lead to gassing/foaming, loss of isocyanate functionality, low gloss and a reduced pot life. To compensate for this side reaction, these formulations usually contain a large excess of isocyanate. Tin compounds, especially dibutyltin dilaurate, are widely used in coatings as catalysts for the isocyanate/hydroxyl reaction. Because of the high aquatic toxicity of some organotin compounds, there has been an attempt to ban organotin compounds from all coating applications. As a general rule, organotin catalysts are not selective, they catalyze the reaction of isocyanates with both hydroxyl groups and water and also catalyze the hydrolysis of ester groups. One novel approach to control the water side reaction is the use of catalysts which selectively catalyze the isocyanate-polyol reaction and not the isocyanate-water reaction. The selectivity of a variety of metal catalysts (metal octoates, metal acetylacetonates and mangan chelates with mixed ligands) to catalyze the preferred reaction was measured using the FTIR method.
In vitro evaluation of the controlled release of antibiotics from liposomes
Authors: Boltic Zorana , Petkovska Menka , Obradovic Bojana , Nedovic Viktor , Bugarski Branko
Published: July 2008

Results of this study have shown significantly prolonged release of selected antibiotic from liposome dispersion as compared to free antibiotic solution of the same initial concentration. Two models of non-steady one-dimensional diffusion were successfully applied to the experimental data and the antibiotic diffusion coefficients were estimated. In addition, the mass transfer resistance of the membrane was shown to be insignificant confirming the suitability of the applied experimental system. Since liposomes are known as systems with slower drug release, then, when it comes to their incorporation in the final form of a preparation for further experiments in vivo, the system of choice would be liposomes with an encapsulated antibiotic drug. The established experimental system could be extended to other liposome formulations with respect to the release rate of the active components.
Mechanical characterization of calcium pectinate hydrogel for controlled drug delivery
Authors: Chung Jin , Zhibing Zhang
Published: July 2008

Calcium pectinate beads, a paniculate hydrogel system, is an attractive drug carrier for oral delivery. In this study, a poorly water-soluble model drug indomethacin was incorporated into calcium pectinate beads made of different pectin concentrations, which were produced by an extrusion method. The effect of pectin concentration on bead size, circularity, swelling behavior, and mechanical properties, as well as in vitro drug release profile was investigated. The mechanical properties of calcium pectinate beads were determined by a micromanipulation technique. The drug release profile was measured using a standard British Pharmacopoeia method. It was found that the beads made of higher pectin concentration in general had a less permeable matrix structure and greater mechanical rigidity, although they swelled more after hydration. However, such an effect was not significant when the pectin concentration was increased to above 8%. Micromanipulation measurements showed that there was significant relaxation of the force being imposed on single hydrated beads when they were held, but this phenomenon did not occur on dry beads, which means that the force relaxation was dominated by liquid loss from the beads. The rate of the force relaxation was determined, and has been related to the release rate of the model drug entrapped in the calcium pectinate beads.
Fluidization control in the wurster coating process
Authors: el Mafadi , Hayert Murielle , Poncelet Denis
Published: July 2008

Paniculate coating process in a fluidized bed involves different sub processes including particle wetting, spreading and also consolidation or drying of the coating applied. These sub processes are done simultaneously to particle fluidization and motion. All the parameters of fluidization are known to affect the coating quality. That is why the motion of particles in the Wurster coating process has been observed and described step by step. These observations have achieved a general understanding of phenomena which take place inside the bed during fluidization and have allowed the development of an easy method for optimizing all the parameters affecting this operation.
Analysis of the hydrodynamic parameters of external loop air lift bioreactors
Authors: Milivojevic Milan , Dudukovic Aleksandar , Obradovic Bojana , Spasic Aleksandar , Bugarski Branko
Published: July 2008

In this study we analyzed the effects of the hydrodynamic conditions and properties of the working fluid on the operation of external loop air lift bioreactors. In particular, the effects of design and operating parameters (e.g. reactor geometry, design of the gas sparger, superficial gas velocity, flow regime) as well as the fluid properties (liquid viscosity and addition of surfactants) on the liquid superficial velocity and gas hold-up were defined. Several correlations found in the literature based on theoretical models of fluid flow, as well as several semi-empirical and empirical correlations were tested and the applicability of all the proposed correlations was verified on the available experimental data. The most accurate correlations for the prediction of the gas hold up, liquid circulation velocity and slip velocity in each bioreactor operating regime were identified.
Application of plasma technology for the modification of polymer and textile materials
Authors: Radetic Maja , Petrovic Zoran
Published: July 2008

Plasma treatment is based on the physico-chemical changes of the material surface and as an ecologically and economically acceptable process it can be an attractive alternative to conventional modifications. The possibilities of plasma technology application to the modification of polymer and textile materials are discussed. Different specific properties of the material can be achieved by plasma cleaning, etching, functionalization or polymerization. The final effects are strongly influenced by the treatment parameters (treatment time, pressure, power, gas flow), the applied gas and nature of the material. The plasma treatment of polymers is predominantly focused on cleaning and activation of the surfaces to increase adhesion, binding, wettability, dye ability and printability. Current studies deal more with plasma polymerization where an ultra thin film of plasma polymer is deposited on the material surface and, depending on the applied monomer, different specific properties can be obtained (i.e. chemical and thermal resistance, abrasion resistance, antireflexion, water repellence, etc.). Plasma application to textiles is mostly oriented toward wool and synthetic fibres, though some studies also consider cotton, hemp, flax and silk. The main goal of plasma treatment is to impart a more hydrophilic fibre surface and accordingly increase wettability, dye ability, printability and particularly, shrink resistance in the case of wool. Recent studies have favored technical textiles, where plasma polymerization can offer a wide range of opportunities.
A study on the kinetics of ozone decomposition in waters of different quality
Authors: Takic Ljiljana , Lazic Miodrag , Veljkovic Vlada , Pejanovic Srdjan
Published: July 2008

The kinetics of ozone decomposition in waters of different quality, namely distilled water, tap water previously treated with ozone, tap water not treated with ozone and raw water from an accumulation lake, were studied in a batch stirred reactor at different temperatures (18-28?C). The dissolved ozone concentration was measured by the iodometric titration method. It was determined that an empirical kinetic equation of the form: dc(O3)/dt= k0 + k1c(O3) fitted the experimental data better than a first-order reaction rate equation. The apparent reaction rate constants in the case of ozone decomposition in distilled water were shown to be a function of temperature in accordance with the Arrhenius equation.
Modeling of mixing in stirred bioreactors 4. mixing time for aerated bacteria, yeasts and fungus broths
Authors: Cascaval Dan , Galaction Anca-Irina , Oniscu Corneliu , Ungureanu Florina
Published: July 2008

The mixing time for bioreactors depends mainly on the rheoiogicai properties of the broths, the biomass concentration and morphology, mixing system characteristics and fermentation conditions. For quantifying the influence of these factors on the mixing efficiency for stirred bioreactors, aerated broths of bacteria (P. shermanii), yeasts (S. cerevisiae) and fungi (P. chrysogenum, free mycelia and mycelial aggregates) of different concentrations have been investigated using a laboratory bioreactor with a double turbine impeller. The experimental data indicated that the influence of the rotation speed, aeration rate and stirrer positions on the mixing intensity strongly differ from one system to another and must be correlated with the microorganism characteristics, namely: the biomass concentration and morphology. Moreover, compared with non-aerated broths, variations of the mixing time with the considered parameters are very different, due to the complex flow mechanism of gas-liquid dispersions. By means of the experimental data and using a multiregression analysis method some mathematical correlations for the mixing time of the general form: tm = a1*Cx2+a2*Cx+a3*IgVa+a4-N2+a5-N+a6/a7*L2+a8*L+a9 were established. The proposed equations offer good agreement with the experiments, the average deviation being ?6.7% - ?9.4 and are adequate for the flow regime Re < 25,000.
Biodiesel II: A new concept of biodiesel production - transesterification with supercritical methanol
Authors: Skala Dejan , Glisic Sandra , Lukic Ivana , Orlovic Aleksandar
Published: July 2008

Biodiesel is defined as a fuel that might be used as a pure biofuel or at high concentration in mineral oil derivatives, in accordance with specific quality standards for transport applications. The main raw material used for biodiesel production is rapeseed, which contains mono-unsaturated (about 60%) and also, in a lower quantity, poly-unsaturated fatty acids (C 18:1 and C 18:3), as well as some amounts of undesired saturated fatty acids (palmitic and stearic acids). Other raw materials have also been used in the research and industrial production of biodiesel (palm-oil, sunflower-oil, soybean-oil, waste plant oil, animal fats, etc). The historical background of the biodiesel production, installed industrial capacities, as well as Directives of the European Parliament and of the Council (May 2003) regarding the promotion of the use of biofuels or other renewable fuels for transport are discussed in the first part of this article (Chem. Ind. 58 (2004)). The second part focused on some new concepts and the future development of technology for biodiesel production based on the use of non-catalytic transesterification under supercritical conditions. A literature review, as well as original results based on the transesterification of animal fats, plant oil and used plant oil were discussed. Obtained results were compared with the traditional concept of transesterification based on base or acid catalysis. Experimental investigations of transesterification with supercritical methanol were performed in a 2 dm3 autoclave at 140 bar pressure and at 300?C with molar ratio of methanol to triglycerides of about 41. The degree of esterification strongly depends on the density of supercritical methanol and on the possibility of reaction occurring in one phase.
Treatment of the liquid phase from the red mud disposal site of the aluminium plant in podgorica
Authors: Kadovic Milena , Klasnja Mile , Blagojevic Nada , Vasiljevic Rajko , Jacimovic Zeljko
Published: July 2008

The aim of this paper was to investigate the quality of the liquid phase (water) from the red mud disposal site of the Aluminium Plant in Podgorica. Based on theoretical knowledge and experimental results, the water from the red mud disposal site was refined, so that it could sluice in the recipient (Moraca River). Refining of the water achieved the following: 1) reduction of environment pollution and 2) reduction of natural water consumption, which contributed to the preservation of a major environmental resource. The technological treatment of water from the disposal site was based on the selection of the optimal reagent for neutralization, separation of the solid products from that process and sluicing of the treated water into the recipient. The results obtained will be useful in the protection of potable well-water located in vicinity, south of the Aluminium Plant in Podgorica.
Investigation of the influence of cementation of chromium onto aluminium on the characteristics of non-printing elements of an offset printing plate
Authors: Zivkovic Predrag , Ilic Nenad , Popic Jovan , Jovanovic Slobodan , Popov Konstantin
Published: July 2008

The possibility of the electro less deposition of chromium onto aluminum was investigated in order to improve non-printing element properties. It was determined that the electrochemical deposition of trivalent chromium was possible from alkaline solutions. The presence of chromium was confirmed by the EDAX procedure in three different laboratories. The influence of chromium on the wet ability of the nonprinting elements of the printing form was examined by drop spreading. Specimens were examined by pouring distilled water in drops onto the surface of the specimen. The picture of the drop was taken by a digital camera from two directions, in order to measure the diameter of the spreaded drop (a measuring gauge was recorded together with the drop) and contact angle. The chromium-treated samples showed increased wettability compared with the non-chromium-treated samples. Improvement of the non-printing elements was confirmed during a printing test that was performed under real printing conditions. The purity of the prints made by two types of printing forms was analyzed in two ways: based on densitometric measurements and based on statistical analysis of the scanned print. Both methods of analysis of the control prints showed that the control prints made from chromium-treated specimens were purer than the prints made from the non-chromium-treated specimens. Considering that all the conditions of making the printing forms and the printing conditions, except the electro less deposition procedure were the same, it could be concluded that the electro less deposited layer of chromium improved the printing properties of the offset printing form because of the increased wettability.
Anionic surface binders
Authors: Aljaz-Rozic Mateja , Hocevar Nezka
Published: July 2008

The MELAMIN Chemical Factory in Kocevje manufactures synthetic resins and binders for the paper industry. Binders based on AKD (alkyl ketene dimer) are produced which are used for binding paper and cardboard in the range of neutral and partially basic pH. Cationic and, lately, anionic binders are mostly used for the bulk binding of paper and board. The possibility of using AKD binders on paper or board surfaces is presented. In this case partially cationic AKD binders may be applied. When optical whiteners are used, the application of AKD binders is recommended. In the case of paper it is possible to substitute acrylate binders by AKD binders. The best results are obtained when the paper is first partly treated in bulk and subsequently surface treated.
Tunable synthetic approaches for the optimization of nanostructured fuel cell catalysts: An overview
Authors: Bönnemann H. , Nagabhushana K.S.
Published: July 2008

Highly active nanostructured pluri-metal catalysts for fuel cell applications can be obtained by designing synthetic protocol where the particle size, metal composition and morphology can be readily tailored. Tunable synthesis relates to combining the various synthetic methodologies available for generating nanostructured metal catalysts with desired catalytic properties. Herein, we discuss some of these synthetic methodologies which were developed to combine the advantages of each pathway in generating efficient fuel cell catalysts and to learn how the composition and morphology of the metals be fine tuned.
On the materials issues for pefc applications
Authors: Savadogo Oumarou
Published: July 2008

Current limitations related to the development of effective, durable and reliable MEA components for PEFC applications are addressed. Advancements made in the development of materials (catalysts, high temperature membranes, bipolar plates, etc.) for PEFC are shown. The effect of the catalyst on PEFC performances based on cells fed by hydrogen, direct methanol, direct propane, or direct acetal fuels are presented. The progress in cell performance and cathode research are discussed. Perspectives related to CO tolerance anodes are indicated. The effect of the membranes on the cell performance are shown and parameters which may help the development of appropriate membranes depending on the fuel are suggested. Openings for the future in materials processing and development for PEFC mass production are discussed. The development of New Materials is the key factor to meet those requirements. The aim of this paper is to present challenges related to the development of new materials for PEFC applications and perspectives related to components cost issues are discussed.
Rationalization of water consumption in paper industry
Authors: Zarkovic Darja , Krgovic Milorad , Rajakovic Ljubinka
Published: July 2008

The subject of this paper was to consider the possibilities of economical paper production with rationalization of water consumption. In accordance with the principles of viable development. The pulp & paper industry has had to face global market needs and strict regulation concerning the environment. The basic motive was to provide consistent and high product quality, which is competitive on the market. The pulp & paper industry is one of the largest consumers and pollutants of natural resources. In that light, the rationalization of raw material, water, energy and chemicals consumption with minimization of environmental impact is essential. The European directive on environmental protection obliges producers of pulp & paper to decrease the volume of wastewater and to increase the efficiency treatment. Pulp and paper industry in Serbia and Montenegro will also be faced with the demands for environmental protection. Numerous examples of water consumption rationalization and improvement of water quality in the pulp & paper industry could be found in different literature sources. It is necessary to increase water system closure and implement up-to-date treatment methods. The possibilities for water consumption rationalization, in a real system the paperboard mill UMKA, were examined.