bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of two-dimensional fluorescence spectroscopy for monitoring of the effect of dimethyl sulfoxide on the growth and viability of immobilized plant cells
Authors: Vankova Radomira , Kuncova Gabriela , Podrazky Ondrej , Gaudinova Alena , Vanek Tomas
Published: July 2008

The growth and viability of tobacco cells (Nicotiana tabacum L) immobilized in alginate or pectate were monitored during their cultivation by using two-dimensional fluorescence spectroscopy (2-D FS). The cell growth was followed via the fluorescence of amino acids in proteins. The correlation between the tryptophan fluorescence and the cell biomass inside the alginate beads was verified by comparison with the dry weight of the cells. The determination of biomass content or cell viability by measurement of the intensity of NAD(P)H fluorescence was found unsuitable. Cell viability was estimated by determination of cell esterase activity using fluorescein diacetate as a fluorogenic substrate. The fluorescence intensities of both fluorophores, tryptophan and fluorescein, were determined by scanning a 2-D FS spectrum of intact beads in front face cuvette. Using this technique the effect of organic solvent, dimethyl sulfoxide, on the growth and metabolic activities of cells within the beads was evaluated. While 4% DMSO was tolerated by cells, 6% DMSO led to the cell destruction.
Scale-up of the jetcutter technology
Authors: Pruesse Ulf , Jahnz Ulrich , Wittlich Peter , Vorlop Klaus-Dieter
Published: July 2008

The JetCutter is a new, simple and efficient technology for the high throughput encapsulation of various materials inside spherical beads. Monodisperse beads in the particle size range from approximately 0.2 mm up to several millimeters can be prepared at high throughput rates with the JetCutter. The generation of beads is not limited by the fluid viscosity. Thus, also highly viscous fluids even with high loadings of solids, can be processed, which leads to an improved stability of the resulting beads. The JetCutter technology is available in different scales and corresponding throughputs ranging from lab-scale devices (liters per day) up to large scale installations for industrial production purposes (tons per day). The application of the JetCutter for industrial purposes has been well established by geniaLab?, which currently produces more than 40 tons/year of small hydrogel beads.
Mathematical model for exergy in the system NaCl-H2O
Authors: Ninkovic Rozalija , Todorovic Milica , Miladinovic Jelena
Published: July 2008

In this work mathematical models for the exergy and relative enthalpy of the water solution of sodium-chloride and the pure crystalline sodium-chloride where derived. The environment was defined with the temperature 20 ?C, pressure 101,325 kPa and with liquid water and crystalline sodium-chloride, both having at the defined environmental conditions the value of exergy equal zero. The obtained mathematical model is valid in the temperature interval from 0 to 170?C and for the all compositions of solution, until to saturation. The derived mathematical model for the exergy is based on the Pitzer's ion interaction equation which satisfactory represents the dependence of the osmotic coefficient and the mean ionic activity coefficient on the composition of solution. The calculated values of exergy using the mathematical model were compared with the appropriate diagram for the exergy constructed using the table values of activity coefficients, osmotic coefficients and partial molar enthalpies.
Porous and adsorption properties of hydrated cement paste
Authors: Marina Biljana , Brezovska Snezana , Burevski Donco , Panova Biljana
Published: July 2008

Adsorption isotherms of benzene on hydrated cement pastes prepared by cement ground with and without the addition of grinding aids, triethanol amine (TEA) and ethylene glycol (EG) were investigated. The adsorption isotherms were interpreted by means of the Dubinin-Astakhov (DA) and Dubinin-Radushkevich-Stoeckli (DRS) equations. The microporous structure of cement gel (C-S-H) in the cement pastes, and changes in the Gibbs free energy of adsorption were determined. The mechanical properties of the cement pastes were also measured. It was evident that pastes with additives had different parameters of the DRS and DA equations: the volume and dimensions of the gel pores, the distribution of the dimensions, the characteristic energy of adsorption, and the change in the Gibbs free energy of adsorption. The mechanical properties were also different. The dispersity of the additive-containing ground cements had a favorable effect on the hydration processes. When applying TEA, it was also necessary to analyze its influence on the chemical behavior of hydration in the starting period.
Determination of the optimal conditions for obtaining potassium nitro-humate from lignite
Authors: Milicevic Zoran , Petrovic Petar
Published: July 2008

Raw lignite is enriched by humic acids by oxidation with nitric acid. The optimal conditions for producing potassium nitro-humate were defined by investigating the level of neutralization of the oxidized lignite, by means of potassium hydroxide. The increased content of humic acids and potassium in potassium nitro-humate makes it applicable as an organic-mineral fertilizer.
Classification of phosphogypsum as a waste material from the aspect of environmental protection
Authors: Rajkovic Milos
Published: July 2008

Phosphogypsum is primarily classified as a heavy waste. The classification of phosphogypsum as dangerous waste may be only maintained under the condition that phosphates with the highest content of radio nuclides are used in the production of H3PO4 by the so called "wet procedure" (Morocco, Florida), which, due to the great quantity of present radio nuclides, causes considerable environmental pollution by radon. The classification of phosphogypsum as a separate category of radioactive waste may be conditionally accepted, because phosphogypsum is not a radioactive waste. All the instructions about the collection, documentation and storage of phosphogypsum so far on disposal sites, and possible transport, also due to non-existing legal recommendations must comply with the classification of phosphogypsum as dangerous waste.
Dispersions in porous beds
Authors: Secerov-Sokolovic Radmila , Sokolovic Slobodan
Published: July 2008

Dispersions and porous media exist either in nature or in industrial applications. They have been the subject of investigations for a long time, but the complexity of the phenomenon is the major obstacle to its better understanding. Many factors influence the interface interactions, transport, accumulation and detachment of particles in a porous matrix limiting new applications. The current state of investigations which include dispersions in the liquid continuous phase, especially emulsions, liquid/solid interface interactions in porous media and some new mathematical functions were reviewed in this paper.
Study of the dechroming of tanned leather wastes
Authors: Botic Tatjana , Iliskovic Nadezda , Drljaca Dijana
Published: July 2008

According to European legislation, it is not possible to dump any chromium-containing waste in Europe. The minimization of wastes is a key element in that strategy. It involves the application of clean technologies: low and non-waste technologies. The tanning industry generates substantial quantities of chromium-containing solid waste in the form of shavings and trimmings. The recycling and reuse of those wastes must be the primary target in optimizing processes of the leather industry. The problem is in a satisfying chromium separation from collagen fibers. Common hydrolysis processes-alkaline or acidic-give gelatins containing residual chromium (III). By using an oxidation agent (H2O2) before alkaline hydrolysis, in was demonstrated that chromium from chromium-containing leather wastes can be almost fully recovered by the previous oxidation of Cr(III) to Cr(VI). This chromium can be reused in the tanning process. That would represent an economic saving. The best result of the dechroming process was a gelatin hydrolyzate with only 1.11 in respect to the initial amount.
Mass transfer from the wall of a column to the fluid in a fluidized bed of inert spherical particles
Authors: Brzic Danica , Boskovic-Vragolovic Nevenka , Grbavcic Zeljko
Published: July 2008

Mass transfer in fluidized beds is an important operation for separation processes. Two effects can be achieved by using fluidized beds in mass transfer processes increasing interface area and relative movement between the phases. These effects are both desirable because they lead to greater process rates. This paper presents an experimental investigation regarding mass transfer from the wall of a column to the fluid in a fluidized bed of inert spherical particles. The experiments were conducted in column 40 mm in diameter with spherical particles 0,8-3 mm in diameter and water as one fluidizing fluid. The method of dissolution of benzoic acid was used to provide very low mass flux. The average wall-to-fluid mass transfer coefficients were determined for two systems: single-phase fluid flow and a fluidized bed of inert particles The measurements encompassed a Reynolds number range from 100-4000 for single-phase flow and 600-4000 in fluidized beds. The mass transfer coefficients for both systems were calculated from weight loss of benzoic acid. The effects of superficial liquid velocity and particle diameter on the mass transfer coefficient were investigated. It was found that mass transfer was more intensive in the fluidized bed in comparison with single phase flow. The best conditions for mass transfer were reached at a minimum fluidization velocity, when the mass transfer coefficient had the greatest value. The experimental data were correlated in the form: jd = f(Re), where jd is the dimensionless mass transfer factor and Re the Reynolds number.
Biodiesel I: Historical background, present and future production and standards - professional paper
Authors: Skala Dejan , Glisic Sandra
Published: July 2008

Biodiesel is defined as a fuel which may be used as 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 acids (about 60%) and also poly-unsaturated fatty acids (C 18:1 and C 18:3) in a lower quantity, as well as some undesired saturated fatty acids (palmitic and stearic acids). Other raw materials have also been used in research and the industrial production of biodiesel (palm oil, sunflower oil, soybean oil, waste plant oil, animal fats, etc). The historical background of biodiesel production, installed industrial capacities, as well as the Directive 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. The second part focuses on some new concepts for the future development of technology for biodiesel production, based on the application of non-catalytic transesterification under supercritical conditions or the use of lipases as an alternative catalyst for this reaction.
Modeling of the selective pertraction of carboxylic acids obtained by citric fermentation
Authors: Cascaval Dan , Galaction Anca-Irina , Oniscu Corneliu
Published: July 2008

Facilitated pertraction was applied for the selective separation of citric, maleic and succinic acids from a mixture obtained by citric fermentation. The pertraction equipment included a U-shaped cell containing 1,2-dichloro-ethane as the liquid membrane and Amberlite LA-2 as the carrier. The experimental data indicated that maleic and succinic acids can be initially selectively separated from citric acid, followed by the selectively separation of maleic acid from succinic acid. Using statistical analysis and a second order factorial experiment, two mathematical correlations describing the influence of the main process variables on pertraction selectivity were established. For both extraction systems, the considered variables controlled the extraction process to an extent of 92.9-99.9%, the carrier concentration inside the liquid membrane exhibiting the most important influence.
Aromatization of light naphtha fractions on zeolites: 2. Model of catalyst deactivation
Authors: Ostrovski Nikolaj , Rovenskaja Svetlana , Echevski Genadij
Published: July 2008

A model of catalyst deactivation in the "Zeoforming" process was developed. The deactivation rate constants and activation energies were estimated. The role of adsorbed oligomers in the reaction and the deactivation kinetics were examined. The model is intended for further modeling and optimization of the process.
Antimicrobial effect of raw garlic (allium sativum L.) extracts, garlic powder and oil and commercial antibiotics on pathogen microorganisms
Authors: Nikolic Vesna , Stankovic Mihajlo , Nikolic Ljubisa , Cvetkovic Dragan , Skala Dejan
Published: July 2008

Garlic powder, essential oil and aqueous extracts from raw garlic and garlic powder prepared in accordance with the corresponding procedures were tested for antimicrobial activity on Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 25922, Bacillus subtilis 6633, Sarcina lutea ATCC 4391, Pseudomonas aeruginosa ATCC 9027, Salmonella enteritidis, Klebsiel la pneumoniae, Proteus vulgaris, Candida albicans ATCC 10231 and Aspergillus niger ATCC 16404; and, three pathogen microorganisms isolated from human material were also used: Staphylococcus aureus, Escherichia coli and Candida albicans. The antimicrobial activities of the preparations were compared with that of commercial antibiotics and four commercial preparation based on garlic powder and essential oil. Aqueous extracts from raw garlic, from freshly prepared powder and powder stored for 18 months at +4?had the greatest antibacterial and antimycotic activities on all the microorganisms tested. The essential oil obtained by hydro distillation and commercial preparations based on garlic essential oil showed no antimicrobial activity on the microorganisms tested. Thermal oils showed a bacteriostatic or very weak bacteriostatic effect on all the microorganisms except Pseudomonas aeruginosa. The garlic powder and commercial preparations based on the powder have a strong antimicrobial effect on all the microbes except on Pseudomonas aeruginosa.
Rapid laboratory method for the detection of chlorine in water
Authors: Savic Jasmina , Simic Slobodanka , Vukelic Nikola
Published: July 2008

The possibility of chlorine detection in water by using of amperometric sensor with dialysis membrane was investigated. The sensor consists of platinum cathode and silver anode, which were immersed in electrolyte whose pH was controlled. The calibration diagrams were constructed for different electrolytes and polarization potentials. The detection limit of 0.1 mg/dm3 was obtained, middle value of sensor sensitivity was approximatelly 14 nA/mgdm'3 and response time was less than 1 s for designed amperometric sensor in laboratory conditions.
The chemical plant management qualitative support system
Authors: Savkovic-Stevanovic Jelenka
Published: July 2008

The aim of this paper was to capture the benefits of common sense qualitative reasoning about process phenomena as displayed in the human behavior mental model. The control features of qualitative modeling and simulation were qualitative variable description and logic rules for manipulating variable values between systematic states. The additional measure of qualitative information value was introduced. This study is the first report in the literature showing the measure of qualitative information value. Qualitative simulation was applied to the fault diagnosis of a chemical system. The obtained results illustrated the goodness of the estimation of system behavior during an abnormal situation. The developed qualitative simulator for fault diagnosis generates original scenarios and can serve as a useful aid to a system operator.
Challenges for chemical sciences in the 21st century
Authors: Cekovic Zivorad
Published: July 2008

Chemistry and chemical engineering have changed very significantly in the last half century. From classical sciences they have broadened their scope into biology, medicine, physics, material science, nanotechnology, computation and advanced methods of process engineering and control. The applications of chemical compounds, materials and knowledge have also dramatically increased. The development of chemical sciences in the scientifically most advanced countries, at the end of the last century was extrapolated to the next several decades in this review and challenges for chemists and chemical engineers are described. Research, discovery and invention across the entire spectrum of activities in the chemical sciences, from fundamental molecular-level chemistry to large-scale chemical processing technology are summarized. The strong integration of chemical science and engineering into all other natural sciences, agriculture, environmental science, medicine, as well as into physics, material science and information technology is discussed. Some challenges for chemists and chemical engineers are reviewed in the following fields: i) synthesis and manufacturing of chemical products, ii) chemistry for medicine and biology, iii) new materials, iv) chemical and physical transformations of materials, v) chemistry in the solving of energy problems (generation and savings), vi) environmental chemistry: fundamental and practical challenges.
The availability of scientific information in Serbia: Trends and perspectives
Authors: Kosanovic Biljana
Published: July 2008

Most of the acquisition of foreign scientific and technical information in Serbia is carried out through KoBSON (Consortium for Coordinated Acquisition). The main goal of this article was to make a survey of all the subscribed resources and to present some statistical data about their usage. Special attention was paid to the availability of information on chemistry (SciFinder: Chemical Abstracts from 1906. to the present day) and similar disciplines. Recent activities within KoBSON as well as activities that will be launched in order to improve the efficiency of usage of the subscribed resources, are reviewed.
Total design for textile products
Authors: Zafirova Koleta
Published: July 2008

Product development is less than 20-30 years old and a relatively new area of research compared to the other classic academic disciplines. Integrated product development is a philosophy that systematically employs the teaming of functional disciplines to integrate and concurrently apple all the necessary processes to produce an effective and efficient product that satisfies customer needs. Product development might also be understood as a multidisciplinary field of research. The disciplines directly participating in product development include engineering design, innovation, manufacturing, marketing and management. A background contribution is also generated by disciplines such as psychology, social sciences and information technology. This article is an overview that introduces this philosophy to textile product development.
Technology and competition as challenges of development
Authors: Todosijevic Radmilo
Published: July 2008

Technology stimulates output and creates new demand. The introduction of new technologies usually causes an increase in investments, which creates more jobs in companies that produce capital goods. Competition occurs as a function of output quality. On the other hand, technology reduces costs by increasing efficiency in regard to output. This leads to one of three effects: the prices of the denoted products or services decrease, the wages in industries that apply new technologies increase, and profits increase. These three effects are the results of competitiveness as expressed by technology. The significant characteristics of technologies are: increase in productivity, quality improvement, cost reduction, flexibility, reliability, security, etc. They are, actually, the basic prerogatives for competitiveness. By deciding on a new technology, the general characteristics of every individual technology are assessed in order to ensure the technical and economic justification for its implementation.
Present status and future development in the world production of fibers and paper
Authors: Krgovic Milorad , Jovanovic Slobodan
Published: July 2008

During 1994 278 million tons of paper were produced worldwide, while around 330 million tons were produced in 2002. The forecast for paper production in 2010 is 420 million tons. From these data, it may be concluded that the paper production industry, which exists for around 2000 years, is still a very attractive industrial branch. This work represents the conditions in the production of the major and auxiliary raw materials for paper production, as well as paper production in the World and production forecasts until 2010. It was indicated that the fraction of secondary fibers obtained from recycled paper increases every year in regard primary fibers. In 2010 secondary fibers will be the major source of primary raw materials for paper production in the World. It was pointed out that in the last fifteen years the quantity of paper produced during one season grew rapidly. This growth was achieved by advance stock preparation of paper and increased velocity of the paper machine and the width web of the produced paper. Activities regarding environmental protection undertaken by manufacturers of paper and fibers are presented.
Hemp as a raw material for fiber and paper production
Authors: Krgovic Milorad , Mijatovic Boris , Nikolic Srecko , Borna Nadezda
Published: July 2008

The goal of this study was to prove the feasibility of fiber and paper production from hemp. Experimental tests of the properties of paper obtained from hemp woody core fibers were performed. Fibers from hemp woody core were isolated by a chemical-thermo-mechanical procedure. Sheets of paper were made from thus isolated fibers. The mechanical and optical properties of the paper sheets were also examined. The properties of paper sheets obtained from spruce and beach fibers were examined in the same way for comparison. The obtained results showed that paper produced from fiber isolated from hemp woody core by a chemical-thermo-mechanical procedure had poorer properties than the properties of paper produced from beech and spruce fibers, but it still satisfied conditions for producing low quality newspaper.
High yield CTMP fibres as a possibility of the more efficient yield of wood raw material
Authors: Klasnja Bojana , Kopitovic Spiro , Herak Stanislav
Published: July 2008

The evident shortage of wood as a raw material has become a limiting factor in the pulp and paper industry which is the greatest consumer of wood in Europe. The situation in our country is similar. During the few past years, the production of poplar and willow pulpwood was 220.000 m3 per year, which is insufficient for the planned increase in the production of sulphate pulp (175.000 tons till 2005). This paper deals with the aspects of the more efficient yield of raw material, based on the significantly higher yield of CTMP fibres, as well as with the significance of the lower adverse effect on the environment. It also analyses the conditions of production and the quality of the obtained fibres, as a possible substitute for chemical pulp and secondary fibres in papers of different quality. The main reasons for the production and use of CTMP fibres in our country are reported.
Computer integration of cardboard production
Authors: Lukic Ljubomir , Andjelkovic Zoran , Stamatovic Suzana
Published: July 2008

A company for the development of software for industrial applications "PBS" Belgrade has designed a modern information system for monitoring and controlling production in the paper industry, which is completely integrated with the technological equipment and production processes. The paper presents the complete concept of the system, from electronic communication with business partners over computer support to all the production processes in the factory, to the delivery of the products to the customers. Realized as a CIM (Computer Integrated Manufacturing) system, it enables management to have a complete overview of the condition of all the production and business activities, and ensures momentary and complete reliable information about all the parameters of the business system. Although the system was developed for the needs of the cardboard factory "Umka", with particular modifications, it could also be used in other factories of the paper and cardboard packaging industry.
Comparative possibilities of using limestone "Visocica" and dolomite "Virpazar" as fillers in paper production
Authors: Krgovic Milun , Blagojevic Nada , Blagojevic Nikola
Published: July 2008

Non-metallic mineral fillers strongly influence the characteristics and quality of paper. "Visocica" limestone and "Virpazar" dolomite were used to prepare paper samples in this study. The characteristics of such paper samples produced on a laboratory paper machine are presented. The used fillers and paper pulp were also characterized. The following paper characteristics were investigated: gramature, thickness, softness, air permeability, resistance to tearing and stretching, paper ash and retention. The experiments were performed in order to compare the influence of the physico-chemical and structural qualities of the examined carbonate type fillers on the paper properties. The results of the investigation indicated the technological reasons for using these non-metallic mineral raw materials as fillers in the paper industry regarding the mechanical paper characteristics, as well as other properties.
Energetic and exploitation characteristics of a two-phase ejecting vacuum system built in the paper machine at A.D. Komuna Skopje
Authors: Sarevski Milan , Sarevski Vasko , Ristovski Voislav , Stavrev Nikola
Published: July 2008

This work presents the concept of a two-phase ejecting vacuum system. The energetic characteristics of these systems were analyzed and compared to those with mechanical pumps with water ring and turbo compressor vacuum pumps. A method for optimizing a two-phase thermo compressor vacuum systems is presented. The analysis included the exploitation characteristics of the system developed at A.D. "Komuna" Skopje.
New drive and control concept of the paper-board machine at the board factory "Umka"
Authors: Jeftenic Borislav , Bebic Milan , Milojevic Miodrag , Belincevic Mario
Published: July 2008

This paper describes the reconstruction of the drives of a paper machine for the press and drying part of the machine during June, 2001, as well as the expansion of the paper machine with a "third coating" during July, 2002 at the board factory "Umka". The existing old drive of the press and the drying groups was realized as a 76 meter long line shaft drive. The coating section of the machine was realized with sectional drives with DC motors fed from thyristor converters. The concept of the new drive is based on standard squirrel cage induction motors, fed from frequency converters. The system is controlled by a programmable logic controller. The communication between the controller, frequency converters and control panels is realized with a profibus protocol. The Laboratory for Electric Drives, of the Faculty of Electrical Engineering, Belgrade, was contracted for the drive part of the reconstruction of the paper-board machine. The complete project, supervision of the work of the investor's own technical services and final commissioning of the drives were organized in such a way that the drives were changed during the planned periods for the repair of the machine.
Unusual kinetic behavior in cathodic H2 evolution from KF.2HF melts at mild-steel and alloy electrodes
Authors: Conway Con , Qian S.Y.
Published: July 2008

Apart from its interest as a "model" process for kinetic studies of gas-evolving electrode reactions, the cathodic hydrogen evolution reaction (her) is involved in several processes that are of importance in applied electrochemistry, e.g., as the cathodic co-reactions in the commercial production of C12 and F2, in electrolyses for production of hydrogen, in electrochemical hydrogenation and, indirectly, as the partial process in corrosion of base metals in the absence of oxygen. The present paper reports several aspects of the unusual behavior of the her that is involved as the co-reaction to electrolytic production of F2 from KF/HF melts using carbon anodes and Fe or mild-steel cathodes. Anomalous anodic polarization behavior that arises in electrolytic generation of F2 from KF/HF melts at carbon electrodes is well known. It is characterized by very high Tafel slopes associated with "CF" film formation and by sluggish F2 bubble disengagement from the electrode. Interest in such effects has, however, tended to overshadow rather similar, so-called "hyper polarization" effects that also arise in the cathodic reaction, but for different reasons. The origins and nature of such effects are described and characterized in the present paper, and comparisons are made between behavior of Hz evolution from KF.2HF and that from the aquo-system analogue, KOH.2H2O. An important aspect is the very different interfacial behavior in KF/HF or KF.2HF melts from that in the corresponding aquo-system. Effects of As-species in HF feeds is investigated in terms of electro catalysis and poisoning effects on the her.
Electrochemistry and new materials
Authors: Petrii Oleg
Published: July 2008

The prognoses of the advance and possible achievements in the field of refining materials for electrochemical devices, like any other predictions of new scientific discoveries are an extremely complicated and ungrateful task. As one classic said, "... it is always hard to predict, especially if this concerns future...".
Sorption properties of wool
Authors: Radetic Maja , Jocic Dragan , Jovancic Petar , Rajakovic Ljubinka
Published: July 2008

Strict ecological legislation, especially in highly developed countries, imposed requirements for the purification of industrial effluents and the need for efficient oil clean up after sea and inland water spills. Although numerous processes have been developed, the application of sorbents is still one of the most efficient methods to remove heavy metal ions, dyes and crude oil from water. Recently, special attention was paid to sorbents based on natural fibres. A review of studies concerning the sorption properties of wool is presented in this paper. The presence of various functional groups on the wool fibre surface contributes to the efficient sorption of heavy metal ions and dyes. A hydrophobic, scaly surface and fibre crimp strongly influence the high sorption capacity of wool for oil. Wool has great sorption potential even as a recycled material. Accordingly, it can be used as a viable substitute to commercially available synthetic sorbents that show poor biodegradab ility.
Enzymatic hydrolysis of potato starch and ethanol production
Authors: Lazic Miodrag , Raskovic Suzana , Stankovic Mihajlo , Veljkovic Vlada
Published: July 2008

The hydrolysis of potato starch using one (Termamyl or Fungamyl) and two combined (Termamyl and Supersan) commercial enzyme preparations and ethanol production from the hydrolysates obtained using the yeast Saccharomyces cerevisiae were studied. Potato tubers were previously prepared as mash or flour. The study dealt with the effects of the hydromodulus (1:1 and 1:0.5), particle size (0.1, 0.2 and 0.4 mm) as well as the type and concentration of enzyme on the enzymatic hydrolysis of potato starch. The highest dextrose equivalent (79.3%, DE) was achieved during two-enzyme hydrolysis (combination of two enzyme preparations: Termamyl 14.4 KNU/dm3 and Supersan 28.8 AGU/dm3) of starch from potato flour (particle size: 0.1-0.2 mm) at an inital starch concentration of 75 g/dm3. During the two-enzyme hydrolysis, a lower DE (61%) was achieved when potato mash was used as a starch source. Using Termamyl (14,4 KNU/dm3) and potato mash a higher DE was achieved at the hydromodulus 1:1 (51.2%) than at the hydromodulus 1:0.5 (40.9%). The highest ethanol concentration (5.0 vol%) was obtained when the hydrolyzate of potato flour from the two-enzyme process was used as a substrate for alcoholic fermentation.
Enalapril: Synthesis and properties
Authors: Mijin Dusan , Stankovic Milena , Petrovic Slobodan
Published: July 2008

Enalapril was originally synthesized by Merck Sharp and Dohme and is an angiotensin converting enzyme inhibitor. Thus, enalapril is used in the treatment of mild to severe hypertension. Enalapril is chemically (S)-1-[N-[1-(et-hoxycarbonyl)-3-phenylpropyl]-L-alanyl]-L-prolin and although the first synthesis was published in 1980, it can be obtained using different synthetic pathways. This paper describes the synthesis as well as the properties and stability of enalapril.
New extraction techniques on bioseparations: 1. Reactive extraction
Authors: Cascaval Dan , Galaction Anca-Irina
Published: July 2008

The complexity of downstream processes for biosynthetic products constitutes a particularity of industrial biotechnologies, especially because of the biosynthetic product high dilution in fermentation broth, their chemical and thermal liability and the presence of secondary products. For these reasons, new separation techniques have been developed and applied to bioseparations. Among them, reactive extraction, pertraction (extraction and transport through liquid membranes) and direct extraction from broths have considerable potential and are required for the further development of many biotechnologies. This review is structured on two parts and presents our original results of the studies on the separation of some biosynthetic products (antibiotics, carboxylic acids, amino acids, alcohols) by reactive extraction in the first part, and by pertraction and direct extraction from broths without biomass filtration in the second. For all the analyzed cases, these extraction techniques simplify the technologies by reducing material and energy consumption, by avoiding product inhibition, by increasing the separation selectivity, therefore decreasing the overall cost of the product.
Mathematical simulation of catalytic paste flow in a ram extruder
Authors: Zhensa A.V. , Kostutchenko V.V. , Petropavlovskiy I.A. , Filippin V.A. , Koltsova E.M.
Published: July 2008

A mathematical model was developed for the stage of catalyst paste preparation. The mathematical model allows the calculation of solvate film thickness and volume content of the solid phase at any moment of time. Functional dependencies were found, which correlated the solvate film thickness and volume content of the solid phase with the plastic strength and viscosity of catalyst pastes. A range of plastic strength was determined, which ensures the optimum forming properties of the pastes. The mathematical model allowed the determination of the concentrations of the components of the continuous and dispersed phases, which ensured the optimum paste forming rheological properties, which, in turn, influence the end properties of an a-FezOs catalyst. The significant role of the solvate film thickness in the forming properties of pastes was demonstrated.
Fault locator of an allyl chloride plant
Authors: Savkovic-Stevanovic Jelenka
Published: July 2008

Process safety analysis, which includes qualitative fault event identification, the relative frequency and event probability functions, as well as consequence analysis, was performed on an allye chloride plant. An event tree for fault diagnosis and cognitive reliability analysis, as well as a troubleshooting system, were developed. Fuzzy inductive reasoning illustrated the advantages compared to crisp inductive reasoning. A qualitative model forecast the future behavior of the system in the case of accident detection and then compared it with the actual measured data. A cognitive model including qualitative and quantitative information by fuzzy logic of the incident scenario was derived as a fault locator for an ally! chloride plant. The obtained results showed the successful application of cognitive dispersion modeling to process safety analysis. A fuzzy inductive reasoner illustrated good performance to discriminate between different types of malfunctions. This fault locator allowed risk analysis and the construction of a fault tolerant system. This study is the first report in the literature showing the cognitive reliability analysis method.
Essential oil composition of hypericum atomarium boiss
Authors: Gudzic Branislav , Djordjevic Sinisa , Nedeljkovic Jovan , Smelcerovic Andrija
Published: July 2008

The essential oil of Hypericum atomarium Boiss. was analysed for the first time. Seven components were identified, accounting for 83.6% of the total oil. The three most abundant components (isocaryophyllene, y-cadinene and 2.4 diisopropenyl-i-methyl-i-vinyl-cyclohexane) represented 64.5% of the oil. A high content of sesquiterpenes (79.6%) characterized the oil.
Determination of the structural and chemisorption characteristics of granulated active charcoal on the basis of coconut shell
Authors: Milenkovic Dragan , Stoiljkovic Stanisa , Ilic D.R.
Published: July 2008

Wastewater purification and the acquirement of drinking water from water streams that are in most cases recipients of various industrial plants, present a significant problem nowadays. The structural characteristics of granulated active charcoal (GAC) obtained by the carbonization of coconut shells and activated by steam are presented in this paper. The established kinetics of suspending cyanide from aqueous solution using GAC impregnated with copper(II) acetate were studied and a mathematical model estabkusged by a regression - correlation analysis.
Novelties in macromolecular synthesis
Authors: Jovanovic Slobodan , Stoiljkovic Dragoslav
Published: July 2008

In 2003 more than 240 million tons of polymeric materials were produced in the world. The average growth of polymer production in the last five years was about 5 wt.% and it is expected that this trend will continue up to 2008. The results of macromolecular synthesis research for a long period of time have a significant contribution to the continuous economical success of the polymeric materials industry. The most significant results achieved in the last several years in various fields of macromolecular synthesis research are presented in this article.
Polymerization of organized monomers
Authors: Stoiljkovic Dragoslav , Pilic Branka , Radicevic Radmila , Bakocevic Ivana , Jovanovic Slobodan , Panic Davor , Korugic-Karasz Ljiljana
Published: July 2008

The current explanations of olefin and vinyl monomer polymerization propose that monomer molecules are successively added one by one to the growing polymer chain. This may be true if the monomer molecules exist as individual species in a polymerizing system, e.g. in dilute solutions of monomer. There are cases, however, in which monomer molecules are organized: bulk liquid monomer, solid monomer, a monomer monolayer adsorbed on a support, etc. Various supra-molecular species and particles of monomer exist in such cases. In the 1960-ties, Semenov, Kargin and Kabanov proposed a theory of organized monomer polymerization. In the last 25 years, our research group has further developed and applied that theory to various polymerizing systems: the radical polymerization of compressed ethene gas, the radical polymerization of liquid methyl methacrylate, olefin polymerization by transition metals and by Al-based catalysts. An outline of the main achievements are presented in this article.
On the formation of porous structure during the synthesis of macroporous copolymers based on glycidyl methacrylate
Authors: Jovanovic Slobodan , Nastasovic Aleksandra
Published: July 2008

The results obtained during the investigation of the influence of the inert component composition and the type of copolymerization reaction on the porosity parameters of the macroporous copolymer of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGMA) [abbreviated poly(GMA-co-EG-DMA)] are presented. A mixture of cyclohexanol and aliphatic alcohol or non-ionic surfactants with hydrophilic-lipophilic balance values (HLB) of 5 or 9 was used as the inert component. The copolymerization was performed in suspension and in a cast. It was shown that poly(GMA-co-EGDMA) samples with enhanced porosity were obtained in the case of copolymerization in a cast, compared with samples obtained by suspension copolymerization. Also, it was concluded that the inert component solubility parameter cannot be used as the only criterium which determines the formation of the macro porous structure in poly(GMA-co-EGDMA).
Characterization of amyloglucosidase immobilized on the copolymer of ethylene glycol dimethacrylate and glycidyl methacrylate in simulated industrial conditions
Authors: Milosavic Nenad , Prodanovic Radivoje , Jovanovic Slobodan , Maksimovic Vuk , Vujcic Zoran
Published: July 2008

The application of amyloglucosidase immobilized on the macroporous co-polymer of ethylene glycol dimethacrylate and glycidyl methacrylate (poly (GMA-co-EGDMA)) in an enzyme reactor was shown. The higher thermostability of immobilized glucoamylases than the soluble one was demonstrated. Immobilized amyloglucosidase obtained by the periodate method shows two times higher thermo stability than the soluble form. Glucoamylases immobilized on poly (GMA-co-EGDMA) have good mechanical and chemical features in the reactor and when applied in a continuous flow reactor for 28 days no changes are observed. In this period periodate immobilized amyloglucosidase shows no decrease in activity. It showed potential for the continuous production of glucose from starch over a prolonged period of time.
Hyperbranched urethane-acrylates
Authors: Tasic Srba , Bozic Branislav , Dunjic Branko
Published: July 2008

The synthesis, characterization and UV-curing of hyperbranched urethaneacrylates (HB-UA) were investigated in this study. They were evaluated as oli-gomers in model UV curable coatings. HB-UAs were synthesized by reaction of an aliphatic hyperbranched polyester of the second generation (HBRG2) and an isocyanate adduct, obtained by the reaction of isophoronediisocyana-te and different hydroxy alkyl acrylates. Their thermal properties and viscosities depend on the degree of modification of HBRG2 and the type of hydroxy alkyl acrylate used. The introduction of a flexible alkoxylated spacer between the HBP core and acrylate end groups reduces steric hindrance by moving the cross linkable acrylate groups away from the HBP core and increase its reactivity. Due to the presence of abstractable H-atoms in the ?-position to the ether links, HB-UAs based on poly(ethylene oxide) monoacrylate are very reactive and do not show oxygen inhibition. The obtained coatings combine a high cross linking density with flexible segments between the cross links, which results in a good compromise between hardness and flexibility and have the potential to be used in different UV-curing applications.
Reversible addition fragmentation chain transfer polymerization - RAFT
Authors: Avramovic Milena , Katsikas Lynne , Dunjic Branko , Popovic Ivanka
Published: July 2008

The fundamentals of controlled radical polymerization are presented in this review. The paper focuses on reversible addition fragmentation chain transfer (RAFT) polymerization. The mechanism and specifics of this type of polymerization are discussed, as are the possibilities of synthesizing complex macro-molecular structures. The synthesis and properties of RAFT agents, of the general structure Z-C(=S)-S-R, are presented.
Influence of hydroxypropylmethyl cellulose-sodium laurylsulfate interaction on rheological properties of the solution
Authors: Saletic Jelena , Sovilj Verica , Petrovic Lidija
Published: July 2008

Interactions between the polymers and surfactants in solution have widely been investigated because of their scientific and technological importance. These interactions can be utilized to modify the physicochemical properties of system in many food products, pharmaceutical formulations, personal care products, paints, pesticides, etc. Interaction between nonionic polymer - hydroxypropylmethyl cellulose (HPMC) and anionic surfactant - sodium laurylsulfate (SDS) in solution has been investigated in this paper by rheological measurements. Rheological measurements are performed by rotational viscometer at 20?C and changes of rheological characteristics of HPMC solutions (0.5-1.5%) with increasing SDS concentrations (0-4.0%) were determined. The results of these investigations showed that viscosity of the solution is dependant on HPMC-SDS interaction. At particular SDS concentration viscosity increases, reach maximum and after that decreases until reach constant value. From the viscosity changes the characteristic concentrations of SDS, critical aggregation concentration (cac) and polymer saturation point (psp), were determined. These concentrations are in linear relationships with HPMC concentrations. Rheological properties of the solution are strong influenced by HPMC-SDS interaction and exhibits more or less pronounced pseudoplastic behavior, which changes to Newtonian one after the psp has been reached.
New extraction techniques on bioseparations: 2. Pertraction, direct extraction
Authors: Galaction Anca-Irina , Cascaval Dan
Published: July 2008

The second part of this review presents our original results on the separation of some biosynthetic products (antibiotics, carboxylic acids, alcohols) by pertraction and direct extraction from broths without biomass filtration. For the analyzed systems, the experimental conditions required for reaching maximum separation efficiency and the mathematical models describing the process have been established. For all the studied cases, these extraction techniques simplify the technologies and reduce the overall cost of the product.
Benzazole derivatives: V. The reactivity of some 2-p-tolyl-and 2-p-methylstyryl-benzimidazolium salts
Authors: Cernatescu Corina , Comanita Eugenia
Published: July 2008

The reactivity of the p-substituted methyl group in 1-methyl-2-p-tolylbenzimidazolium and 1-methyl-2-p-methylstyrylbenzimidazolium iodides with p-nitroso-dimethylaniline (p-NDMA) and aromatic aldehydes was studied. According to literature data on the steric effects produced by the bulky N-l methyl group, the 2-p-tolyl substituted salt does not react with p-NDMA. On the other hand, 2-p-methylstyryl substituted salts give condensation reactions, similarly to 1,2,3-trimethylbenzimidazolium iodides. The compounds obtained from the reaction with aromatic aldehydes can be used as dyeing substances, photosensitizers or as dienic monomers, due to the conjugated chain from C-2.
The extraction of total lipids from parsley: Petroselinum crispum (mill.) Nym. Ex. A.W. Hill) seeds
Authors: Stankovic Mihajlo , Stojanovic Nadica , Nikolic Nada , Novkovic Vesna
Published: July 2008

The kinetics of extraction of total lipids from ground parsley (Petroselinum crispum (Mill.) Nym. ex. A.W. Hill) seeds with a mixture of ethanol or methanol with non-polar organic solvents, chloroform, carbon tetrachloride, trichloroethylene and petroleum ether, at various temperatures were studied. The maceration technique with reflux was used. The kinetic parameters were determined in extraction kinetic equations, as well as the optimal operation conditions for total lipids extraction. The maximum total lipids yield under optimal conditions was 33.7 g per 100 g of dry parsley seeds. Nine lipid fractions of the total lipids were separated by thin layer chromatography among which were phospholipids, sterol, mono-, di- and triacylglycerol, free fatty acids and carbohydrates.