bluuebunny/crossref_metadata_2025 huggingface dataset:
Gradual or pulsed evolution: when should punctuational explanations be preferred?
Authors: Hunt Gene
Published: July 2008

The problem of gradual versus punctuated change within phyletic lineages can be understood in terms of the homogeneity of evolutionary dynamics. Hypotheses of punctuated change imply that the rules governing evolutionary change shift over time such that the normal dynamics of stasis are temporarily suspended, permitting a period of net evolutionary change. Such explanations are members of a larger class of models in which evolutionary dynamics are in some way heterogeneous over time. In this paper, I develop a likelihood-based statistical framework to evaluate the support for this kind of evolutionary model. This approach divides evolutionary sequences into nonoverlapping segments, each of which is fit to a separate evolutionary model. Models with heterogeneous dynamics are generally more complex—they require more parameters to specify—than uniform evolutionary models such as random walks and stasis. The Akaike Information Criterion can be used to judge whether the greater complexity of punctuational models is offset by a sufficient gain in log-likelihood for these models to be preferred.

I use this approach to analyze three case studies for which punctuational explanations have been proposed. In the first, a model of punctuated evolution best accounted for changes in pygidial morphology within a lineage of the trilobiteFlexicalymene, but the uniform model of an unbiased random walk remains a plausible alternative. Body size evolution in the radiolarianPseudocubus vemawas neither purely gradual nor completely pulsed. Instead, the best-supported explanation posited a single, pulsed increase, followed later by a shift to an unbiased random walk. Finally, for the much-analyzed claim of “punctuated gradualism“ in the foraminiferaGloborotalia, the best-supported model implied two periods of stasis separated by a period of elevated but not inherently directional evolution. Although the conclusions supported by these analyses generally refined rather than overturned previous views, the present approach differs from those prior in that all competing interpretations were formalized into explicit statistical models, allowing their relative support to be unambiguously compared.
Body size, energetics, and the Ordovician restructuring of marine ecosystems
Authors: Finnegan Seth , Droser Mary L.
Published: July 2008

Major shifts in ecological dominance are one of the most conspicuous but poorly understood features of the fossil record. Here we examine one of the most prominent such shifts, the Ordovician shift from trilobite to brachiopod dominance of benthic ecosystems. Using an integrated database of high-resolution paleoecological samples and body size data, we show that while the average local richness and relative abundance of trilobites declined significantly through the Ordovician, the estimated standing biomass of trilobites, and by implication the amount of energy that they used, remained relatively invariant. This is attributable to an increase in the average body size of trilobite species in our data set, and especially to the widespread occurrence of the exceptionally large Middle-Late Ordovician trilobite genusIsotelus. Brachiopods increase in both mean body size and relative abundance throughout the Ordovician, so that estimates of brachiopod biomass and energetic use increase substantially between the Early and Late Ordovician. Although the data set includes a range of depositional environments, similar trends are observed in both shallow subtidal and deep subtidal settings. These results suggest that diversification of the Paleozoic Fauna did not come at the energetic expense of the Cambrian Fauna. The declining relative abundance of trilobites may reflect a combination of numerical dilution and the necessary energetic trade-offs between body size and abundance.
A possible role of osteocalcin in the regulation of insulin secretion: human in vivo evidence?
Authors: Kassi Eva , Papavassiliou Athanasios G
Published: July 2008

Recent studies have indicated a novel function for skeleton unraveling its importance in the control of energy metabolism. In the present commentary, we speculate on the meaning for bone to act as a ‘rheostat’ modulating glucose metabolism, and how the primitive way of communication between bone and energy metabolism through switch on/off genes (like Ptprv) evolved to a more complicated ‘talking’ via gain/loss of hormones activity (like osteocalcin) by carboxylation/decarboxylation process.
A pricing and investment strategy for national roads
Authors: Bayliss D. , Banks N. , Glaister S.
Published: July 2008

Main road traffic has doubled in the last quarter-century and its growth continues. During this time the length of the trunk road network has been reduced by almost a fifth and motorway construction has all but halted. Combinations of additional strategic road capacity and national road pricing are examined to explore what mix of these would provide a package of measures which would ease future congestion whilst maintaining adequate levels of mobility. A combination of ‘efficient pricing’—which would replace the existing road taxation regime—and the provision of an additional 600 lane km of strategic road space a year would reduce congestion and carbon emissions whilst providing the mobility needed for a growing and successful economy. The net revenues from pricing would be more than sufficient to pay for the additional capacity and the higher charges to road users would be more than offset by improved strategic road travel conditions.
Optical characterization of autostereoscopic 3‐D displays
Authors: Järvenpää Toni , Salmimaa Marja
Published: July 2008

Abstract— Display‐measurement methods different from conventional 2‐D display measurements are needed for verifying the optical characteristics of autostereoscopic (3‐D) displays and for comparing different 3‐D display technologies. Industry is lacking standardized measurement methods, and the reported results can not always be compared. The selected set of characteristics discussed in this paper and partly defining the quality of the 3‐D experience are crosstalk, viewing freedom, and optimum viewing distance. Also, more conventional display characteristics such as luminance are discussed, since the definitions for these characteristics in 3‐D mode usually differ from those used for the 2D displays. We have investigated how these chosen 3‐D display characteristics can be objectively measured from transmissive two‐view and multiview 3‐D displays. The scope of this article is to generally define those basic characteristics as well as the different measurement methods. Most of the 3‐D characteristics can be derived from the luminance and colors versus the viewing angle. Either a conoscopic or a goniometric measurement system can be used, as long as the angular and stray‐light properties are suitable and known. The characteristics and methods are currently discussed in the display‐quality standardization forums.
Enhancement of blue‐light‐emission properties for OLED displays by using a polarized light‐recycling structure
Authors: Adachi Masaya , Aratani Sukekazu , Yanagawa Kaoru
Published: July 2008

Abstract— The blue‐light‐emission properties of organic light‐emitting‐diode (OLED) displays must be enhanced to meet the requirements for color purity and luminous efficiency because few blue‐light‐emitting materials meet these requirements. This is particularly true for polymeric and phosphorescent light‐emitting materials. To attain the required purity and efficiency, a polarized‐light‐recycling structure for blue light that is called a blue enhanced circular polarizer (BECP) has been developed. The principle of the structure and the fabricated prototype device is described and it is shown that the structure increases blue‐light intensity and color purity, improves efficiency, provides a wide color gamut, and limits ambient‐light reflection.
A Simulation Study for Planning the Development of la Victoria Field in Western Venezuela
Authors: Joe Cordero Franklin
Published: July 2008

This report presents the results of a case study and development program for the La Victoria field in south-western Venezuela. The La Victoria field was discovered in 1984. Original oil in place is approximately 210 MMSTB (334 × 106 m3 ). To date (Dec. 1989), cumulative production has been 5.3 MMSTB (8.4 × 105 m3).

Excellent reservoir characteristics shown by the Escandalosa and Navay formations, which contain most of the oil in the La Victoria field, exhibit the following unusual oil properties: 35 °API (0.85 g/cm3 ) gravity, low bubble point pressure (285 psia) (1.97 MPa), low solution GOR (136 SCF/STB) (24.5 std m3/m3) and an average oil viscosity of 1 cp (1 × 10−3 Pa.s) at 227 °F (108 °C). These anomalous values make this field one of the most prolific discovered in Venezuela. The producing mechanism is an edge water drive from an extensive, fresh water aquifer.

The development of such a field must be planned properly to achieve a maximum efficiency in its exploitation.

This paper describes the reservoir and its geology, the production history, and the reservoir simulation study used as an aid to development planning.

Results show that the La Victoria field can be developed with eighteen producers. The ultimate recovery by natural depletion, at the end of 20 years, is predicted to be 84.5 MMSTB (13.4 × 106 m3 ) (38.2% STOIP). With the proposed development plan it may be possible to maintain the oil potential production above 30,000 B/D (4,769 m3/D) during the 1990-1992 period.
Geophysical Aspects of Horizontal Well Systems
Authors: Mari J. L. , Laurent J.
Published: July 2008

Among possible characterization techniques used in horizontal wells, geophysical surveys seem to be very promising in giving a set of images of the reservoir and the surrounding layers at different scales. This paper demonstrates the usefulness of horizontal well geophysical surveys in different frequency bandwidths for reservoir studies. The paper shows several field examples. In the low frequency bandwidth, VSPs give a coarse image of the reservoir and of the layers situated below, with a vertical resolution of several 10's of m (first example). Full waveform acoustic data produce near-borehole structure images up to a distance of 15 m from the borehole with a vertical resolution of several 10's of cm (second example).

The paper points out the necessity of having very high resolution seismics (intermediate between VSP data and acoustic data) to obtain structural images up to a distance of 100 m from the borehole. An example shows the results obtained in the 1-to-5 kHz bandwidth on a test site. The field records show reflected arrivals from boundaries up to a distance of 50 m from the horizontal borehole.
A Review of Formation Evaluation Practices in Horizontal Wells
Authors: Donahue Michael T. , Nice Sid B. , Lincecum Val J.
Published: July 2008

The better return on investment that horizontal drilling techniques provide has prompted an increase of this activity worldwide. Initially, it was felt little or no data were required to evaluate the reservoirs produced through horizontal boreholes because early completion techniques consisted of simple openhole completions or placement of a slotted liner along the lateral borehole. However, because of productivity anomalies, a need for thorough evaluation techniques soon became apparent. This paper is a review of the latest techniques used to evaluate horizontal wells. Methods of instrument conveyance, formation evaluation techniques, and measurement-while-drilling applications are included.
The Fracture Intensity Log: A Proven Technique for Evaluating Fracturing in Low-Permeability Reservoirs
Authors: Sanders R. L.
Published: July 2008

The fracture intensity log provides a means for recognizing and evaluating naturally occurring fractures in the wellbore. An analysis of the fracture intensity presentation can then be used in "pipe-setting" decisions. The fracture intensity log is based upon the shear wave properties derived from acoustic full waveform logs.
Hydrocarbon Evaluation of the Delaware Sandstones Using the Shear Wave Travel Time and the Neutron Porosity
Authors: Sanders R. L.
Published: July 2008

A formation evaluation technique is being used to evaluate the Delaware sandstones of the Permian Basin for hydrocarbons. The technique consists of crossplotting the neutron porosity and the shear wave travel time. The sandstones reservoirs that are productive will exhibit a greater shear wave travel time than would be predicted from the neutron porosity. This technique is applicable to both open and cased hole conditions.
Internet Support Groups for Suicide Survivors: A New Mode for Gaining Bereavement Assistance
Authors: Feigelman William , Gorman Bernard S. , Beal Karyl Chastain , Jordan John R.
Published: July 2008

Taken among parents who sustained the loss of a child to suicide this study explores the participation of parents in Internet support groups, comparing their demographic and loss-related characteristics ( N = 104) to other parent survivors participating in face-to-face support groups ( N = 297). Contrary to expectations that Internet affiliates would be concentrated in under-served rural areas, we found similar levels of urban, suburban, small city and rural residents in both Internet and face-to-face subsamples. Bivariate and multivariate analyses suggested several important factors contributing to interest in Internet grief support including: 24/7 availability and opportunities to invest more time into this type of support group experience. Compared to their face-to-face group counterparts, Internet affiliates experienced greater suicide stigmatization from their families and other associates. Unable to find ready comfort and support from their personal communities, Internet users—and especially highly depressed survivors—sought and obtained valuable help from the Internet support resource.
Implementing a Triangulation Protocol in Bereavement Research: A Methodological Discussion
Authors: Briller Sherylyn H. , Meert Kathleen L. , Schim Stephanie Myers , Thurston Celia S. , Kabel Allison
Published: July 2008

Triangulation is a comparative strategy for examining data that strengthens qualitative and multi-method research. Despite the benefits of triangulation noted in the research methods literature, few concrete models for operationalization of protocols exist. Lack of documentation of explicit triangulation procedures is especially true in the area of bereavement research. This article describes how an interdisciplinary research team implemented a triangulation protocol in a study of the needs of bereaved parents. Triangulation enabled the integration of diverse data sources, methods, and disciplinary perspectives. These processes yielded a more meaningful typology of bereaved parents' needs than would have otherwise been possible. Extending the use of triangulation will enhance multi-faceted understandings of bereavement.
Neuroprotectionby MK-801 following cerebral ischemia in Mongolian gerbils
Authors: Radenovic Lidija , Selakovic Vesna , Andjus P.R.
Published: July 2008

Global cerebral ischemia in Mongolian gerbils is an established model in experimental research on cerebral ischemia, which is characterized morphologically by selective neuronal damage in the hippocampus, striatum, and cortex. Elevated glutamate levels are thought to be a primary cause of neuronal death after global cerebral ischemia. The purpose of this study was to investigate the potential neuroprotective effects of dizocilpine malate (MK-801), a non-competitive glutamate antagonist, in the model of 10-min gerbil cerebral ischemia. Gerbils were given MK-801(3 mg/kg i.p.)or saline immediately after the occlusion. On day 4 after reperfusion, neuronal damage was examined in the hippocampus (30 ?m)and striatum slices (5 ?m)stained with hematoxylin/eosin, fluorescent Nissl staining and membrane tracer DiI. The striatum and C3 regions of the hippocampus were analyzed by confocal microscopy. Neuroprotection was determined by quantifying the degree of cell loss, reduction of morphologically damaged cells, and the degree of preservation of recog?nizable neuroanatomical pathways after the ischemic insult. Our results demonstrate that the neuronal damage induced by sustained ischemia is related to abnormalities in glutamatergic function associated with NMDA receptors. MK-801significantly prevented neuronal loss in the tested brain structures. All of this contributes to a better understanding of the given pathophysiological process causing ischemic neuronal damage.

 This article has been corrected. Link to the correction 10.2298/ABS160524054E
Transcription factor p53 exhibits increased binding to the α2-macroglobulin gene promoter and decreased glycosylation in fetal and adult rat liver during the acute-phase response
Authors: Mihailovic Mirjana , Poznanovic G. , Dinic Svetlana , Grdovic Nevena , Vidakovic Melita , Martinovic Vesna , Bogojevic Desanka
Published: July 2008

The binding affinity of p53 for the MG promoter was assessed by DNA-affinity chromatography with the extended ?2-macroglobulin (MG) gene promoter (-852/+12) and immunoblot analysis. During the increased MG gene transcription observed in the fetus and the acute-phase (AP) response in both the fetus and the adult, p53 exhibited increased binding to the MG promoter. This increase was accompanied by decreased O-linked N-acetyl glucosamine glycosylation of p53. We suggest that the enzymatic removal of sugar moieties in vivo serves to activate the MG gene promoter binding potential of p53 and its participation in upregulated MG gene transcription.
Trans-activation of the human SOX3 promoter by MAZ in NT2/D1 cells
Authors: Kovacevic-Grujicic Natasa , Yokoyama Kazunari , Stevanovic Milena
Published: July 2008

In this study, we examine the role of three highly conserved putative binding sites for Myc-associated zinc finger protein (MAZ) in regulation of the human SOX3 gene expression. Electrophoretic mobility shift and supershift assays indicate that complexes formed at two out of three MAZ sites of the human SOX3 promoter involve ubiquitously expressed MAZ protein. Furthermore, in cotransfection experiments we demonstrate that MAZ acts as a positive regulator of SOX3 gene transcription in both undifferentiated and RA-differentiated NT2/D1 cells. Although MAZ increased both basal and RA-induced promoter activity, our results suggest that MAZ does not contribute to RA inducibility of the SOX3 promoter during neuronal differentiation of NT2/D1 cells.
Control of the of the final stage of immune-mediated diabetes by ISO-1, an antagonist of macrophage migration inhibitory factor
Authors: Stojanovic Ivana , Maksimovic-Ivanic Danijela , Al-Abed Y. , Nicoletti F. , Stosic-Grujicic Stanislava
Published: July 2008

We recently showed that attenuation of inflammatory cytokine MIF with pharmacological inhibitor ISO-1 down-regulates the immune-mediated diabetes in mice. Here we explore the effects of MIF neutralization by ISO-1 on the local inflammatory pathway of the disease. In vivo treatment of mice with ISO-1 inhibited the expression of pro-inflammatory cytokines and iNOS in the pancreatic islets. Moreover, ISO-1 affected in vitro cytokine-induced NO pro?duction by fibroblasts, endothelial cells, insulinoma cells, and pancreatic islets, and rescued ? cells from NO-dependent damage. These results suggest regulatory potential of ISO-1 at the level of the pancreas which can preserve the target tissue from autoimmune attack.
Characterization of endopeptidases from the midgut of Morimus funereus (Coleoptera: Cerambycidae) larvae
Authors: Bozic Natasa , Dojnov Biljana , Milovanovic Aleksandra , Nenadovic Vera , Ivanovic Jelisaveta , Vujcic Z.
Published: July 2008

Application of specific chromogenic substrates, use of class-specific inhibitors, and zymogram analysis enabled us to identify several peptidase classes in extracts of the midgut of Morimus funereus larvae. Zymogram analysis with gelatin as a peptidase substrate and phenylmethylsulfonyl fluoride as an inhibitor showed that serine peptidases were the most abundant endopeptidases in the midgut of M. funereus larvae. By zymogram analysis with gelatin as a peptidase substrate and 1,10-phenanthroline as an inhibitor, metallopeptidases were also detected. Analyses of serine peptidases with specific chromogenic substrates revealed dominance of elastase-like peptidases in extracts of the midgut of M. funereus larvae, with less pronounced chymotrypsin- and trypsin-like activities.
Water frogs (Rana esculenta complex) in Serbia: Morphological data
Authors: Krizmanic I.I.
Published: July 2008

The main purpose of this paper was to estimate morphometric variability of the water frog (Rana synklepton esculenta complex) population in Serbia. Altogether, 396 water frogs were collected at 15 localities in Serbia and analyzed using principal components for 18 selected indices, in addition to which correspondent analyses were conducted for 30 qualitative external morphological traits. The results showed that the population samples were heterogeneous and included three separate forms (Rana ridibunda, Rana lessonae and Rana kl. esculenta). Significant interspecific differ?ences were found between R. ridibunda and R. lessonae, which are clearly distinct from each other. Rana kl. esculenta specimens were in an intermediate position between R. ridibunda and R. lessonae, with values more similar to the R. ridibunda parent species.
Breeding site traits of European newts (Triturus macedonicus, Lissotriton vulgaris, and Mesotriton alpestris: Salamandridae) in the Montenegrin karst region
Authors: Cirovic Ruza , Radovic D. , Vukov Tanja
Published: July 2008

We recorded the occurrence of three European newt species - the smooth newt (Lissotriton vulgaris), the eastern alpine crested newt (Triturus macedonicus), and the alpine newt (Mesotriton alpestris) - in the Montenegrin karst, as well as their breeding site characteristics. In terms of long-lasting breeding site numbers and occupation rate, the most common species is the smooth newt, followed by the alpine newt and the crested newt. The examined water bodies with?out newts showed no significant differences of aquatic habitat characteristics compared to water bodies with newts. The factors that explained most of the observed variation in newt breeding site traits were the habitat category and habitat origin. The alpine newt primarily inhabits natural lakes, while the crested newt inhabits artificial breeding sites such as lithotelma and ubao. The smooth newt is less choosy and occurs in different types of natural and artificial habitats. The aquatic requirements of Montenegrin newt species do not differ substantially in many respects from requirements of the core species range populations.
Liverworts from the Moraca River basin: Taxonomic and ecological analysis
Authors: Dragicevic Snezana , Veljic M. , Marin P.D.
Published: July 2008

During the period of 1997-2007, we carried out detailed bryological research in the Moraca River basin, Montenegro. Liverworts were collected at 45 locations. Thirty-five liverworts were recorded, including representatives of 24 genera and 19 families. The most frequent liverwort was Radula complanata, which was found at 17 localities. Seventeen taxa were registered at only one location in the investigated area. Scapania aequiloba is treated as endangered, and Athalamia hyalina as critically endangered, Leiocolea collaris, L. bantriensis and L. turbinata as vulnerable species. In addition, Fossombronia caespitiformis, Lophocolea bidentata var. bidentata, Riccia cavernosa, and Tritomaria quinquedentata are here registered for the first time in the bryoflora of Montenegro.
Basic questions of economic growth mechanism
Authors: Simon György
Published: July 2008

The author elaborated and, by a world economic investigation on 131 countries, verified a growth model considering both physical and human capital, as well as time, as the event space of creative economic activity. The main components of the model are the intensity functions using which one can map the three fundamental types of technical progress and thus economic growth and development from the initial state without physical capital to our days. The model is functioning well concerning both developed and developing countries, as demonstrated by the paper with the examples of the United States and India.
Doha round of WTO negotiations and trade liberalization in Serbian agriculture
Authors: Popovic Vesna , Katic Branko , Cvetkovic Ruzica
Published: July 2008

The accession of Serbia to the WTO is expected in 2008. In negotiations process, the most difficult is to reach agreement in agriculture. This sector is very sensitive in market access for biotechnological, economical and social reasons. The level of sensitivity varies between production branches. In the course of defining the schedules of market access commitments, it is crucial to keep in mind the need of reconciliation dynamics and level of market liberalization with the obligations comprised in the EU Stabilization and Association Agreement. Export support policy also must conform to the Doha negotiations commitments.
Managing IT-related operational risks
Authors: Savic Ana
Published: July 2008

Not so long ago, information technology (IT) risk occupied a small corner of operational risk - the opportunity loss from a missed IT development deadline. Today, the success of an entire financial institution may lay on managing a broad landscape of IT risks. IT risk is a potential damage to an organization's value, resulting from inadequate managing of processes and technologies. IT risk includes the failure to respond to security and privacy requirements, as well as many other issues such as: human error, internal fraud through software manipulation, external fraud by intruders, obsolesce in applications and machines, reliability issues or mismanagement. The World Economic Forum provides best information about this problem. They rank a breakdown of critical information infrastructure among the most likely core global risks, with 10-20 % likelihood over the next 10 years and potential worldwide impact of $250 billion. Sustained investment in IT - almost $1.2 trillion or 29% of 2006 private-sector capital investment in the U.S. alone fuels growing exposure to IT risk. Greg Hughes, chief strategy officer in Symantec Corp. recently claimed "IT risk management is more than using technology to solve security problems. With proper planning and broad support, it can give an organization the confidence to innovate, using IT to outdistance competitors".
Total quality accounting
Authors: Andrijasevic Maja
Published: July 2008

The focus of competitive "battle" shifted from the price towards non-price instruments, above all, towards quality that became the key variable for profitability increase and achievement of better comparative position of a company. Under such conditions, management of a company, which, according to the established and certified system of total quality, strives towards achieving of a better market position, faces the problem of quality cost measurement and determination. Management, above all, cost accounting can help in solving of this problem, but the question is how much of its potential is being used for that purpose.
From the rights of man to the human rights: Man - nation - humanity
Authors: Zaharijevic Adriana
Published: July 2008

The insistence on the fact that human rights and the rights of man (codified in The Universal Declaration of Human Rights and Declaration of the Rights of Man and of the Citizen, respectively) are not one and the same, which could be deduced from the notion of man common to both terms, is the key thesis of this text. By developing this motive, I try to determine the following: that the notion of man, by definition inclusive and abstractly non-discriminative term, is in fact established on tacit exclusions in the time of its inception (Enlightenment revolutinary era), and it was only upon these exclusions that the term man could have signified "the free and equal". Although the parallel or simultaneous evolution and implementation of the rights of man and national rights might seem contradictory, I seek to demonstrate that this paradox is only ostensible, arguing that the notion of man is itself limited and exclusionary, and is therefore compatible with the exclusivity which is the conditio sine qua non of nation. The consequences of nationalism - World Wars, primarily - proved that the conception of liberty and equality, based on the conception of fraternity of men (white European males), and of partial democracy pretending to be universal, cannot be maintained any further. Codification of universal human rights represents a reaction to this internal discrepancy inasmuch as it is a reaction to the destructiveness of all kinds of nationalisms. The notion of life, developed in this text, corresponds to the fundamental requirement for the right to life (as the first and the most basic of all human rights), which no longer belongs to "man", but to everyone.
Culture and/or deception the dialectic of enlightenment
Authors: Velimirovic Tatjana
Published: July 2008

This text deals with Adornos dialectic critic of culture, within which it tries to clarify the relationship between earlier bourgeois culture, on the one hand, and contemporary forms of mass culture, on the other. Adornos understanding of culture enables us to comprehend many specific social forms in their dialectic relationship and their mutual determination. The text itself, first of all, examines the changes that contemporary industrial society brought in regard to critic potential of culture, namely the way in which it achieves to convert, once useless-provocative, culture into useful-impotent culture. Here is analyzed the influence of manufactural industry of high and mass culture on individual consciousness - namely upon mass consciousness - as well as the way in which individuals are being fooled for the things that are said to be offered by the culture. It is asserted that the triumph of manufacturing in cultural industry fooles men for the offer it seemingly gives, and therefore, that it has today become almost impossible to practice individuation, and therewith to hold a critical distance toward ruling forms of material and spiritual manufacturing.
Neutron activation analysis of multimetallic accumulation in dolomites
Authors: Zovko Emira , Pujic Zdravko , Cehic Zijad , Bandic Jasmina
Published: July 2008

The reason for exploring polymetallic ores, which are found in dolomite structures of the Veovaca and Borovica zone near Vares, lies in the fact that there is very little information about its chemical structure. The isolated concentrates that we analyzed from surface mines, have shown significant difference in quantity of trace elements. Deep probing of the whole area was not performed, but there are presumptions that there are roots of ore-rich dolomites in the areas of 30 - 40 km. The future concept of exploitation of these mines in the Vares zone would probably require deeper probing. There are prospects for finding higher quality deposits with significant quantities of polymetallic components. By the method of neutron activation analysis the existence of mercury in amounts of about 0.4 % was confirmed. Because of the presence of mercury, these concentrates are not appropriate for pyrometallurgy, since it may result in environment contamination.
Viscosity sinergism of hydrozypropmethyl and carboxy methyl cellulose
Authors: Katona Jaroslav , Sovilj Verica , Petrovic Lidija
Published: July 2008

Rheology modifiers are common constituents of food, cosmetic and pharmaceutic products. Often, by using two or more of them, better control of the product rheological properties can be achieved. In this work, rheological properties of hydroxypropymethyl cellulose (HPMC) and sodium carboxymethyl cellulose (NaCMC) solutions of different concentrations were investigated and compared to the flow properties of 1% HPMC/NaCMC binary mixtures at various HPMC/NaCMC mass ratios. Solutions of HPMC and NaCMC were found to be pseudoplastic, where pseudoplasticity increases with increase in the macromolecules concentration. Changes of the degree of pseudoplasticity, n as well as the coefficient of consistency, K with the concentration are more pronounced in HPMC solutions when compared to the NaCMC ones. This is mostly due to the ability of HPMC molecules to associate with each other at concentrations above critical overlap concentration, c , and greater flexibility of macromolecular chains. Binary mixtures of HPMC/NaCMC were also found to be pseudoplastic. Experimentally obtained viscosities of the mixture were proved to be larger than theoretically expected ones, indicating viscosity synergism as a consequence of HPMC-NaCMC interaction. Maximum in synergy was observed when HPMC/NaCMC mass ratio was 0.4/0.6, no matter of the shear rate applied. On the other hand, it was found that relative positive deviation, RPD decreases when shear rate is increased.
Low concentration volatile organic pollutants removal in combined adsorber-desorber-catalytic reactor system
Authors: Arsenijevic Zorana , Savcic Gordan , Rankovic Dragan , Grbic Bosko , Radic Nenad , Garic-Grulovic Radmila , Grbavcic Zeljko
Published: July 2008

The removal of volatile organic compounds (VOCs) from numerous emission sources is of crucial importance due to more rigorous demands on air quality. Different technologies can be used to treat the VOCs from effluent gases: absorption, physical adsorption, open flame combustion, thermal and catalytic incineration. Their appropriateness for the specific process depends on several factors such as efficiency, energy consumption, secondary pollution, capital investments etc. The distinctive features of the catalytic combustion are high efficiency and selectivity toward be?nign products, low energy consumption and absence of secondary polluti?on. The supported noble catalysts are widely used for catalytic incineration due to their low ignition temperatures and high thermal and chemical stability. In our combined system adsorption and desorption are applied in the spouted bed with draft tube (SBDT) unit. The annular zone, loaded with sorbent, was divided in adsorption and desorption section. Draft tube enabled sorbent recirculation between sections. Combustion of desorbed gases to CO2 and water vapor are realized in additive catalytic reactor. This integrated device provided low concentrations VOCs removal with reduced energy consumption. Experiments were conducted on a pilot unit of 220 m3/h nominal capacity. The sorbent was activated carbon, type K81/B - Trayal Corporation, Krusevac. A sphere shaped commercial Pt/Al2O3 catalyst with "egg-shell" macro-distribution was used for the investigation of xylene deep oxidation. Within this paper the investigations of removal of xylene vapors, a typical pollutant in production of liquid pesticides, in combined adsorber/desorber/catalytic reactor system is presented.
Adsorption of T-2 toxin by natural mineral adsorbents
Authors: Stojanovic Ana , Dakovic Aleksandra , Matijasevic Srdjan , Rottinghaus George , Sekulic Zivko , Stanic Tanja
Published: July 2008

The contamination of animal feed with mycotoxins represents a worldwide problem leading to economic losses in animal production. According to the Food and Agriculture Organization (FAO), 25% of the world's cereal grain production is contaminated with mycotoxins. The most common mycotoxins found in grains are the aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone and the ergopeptine alkaloids. Trichothecenes, constitute the largest group of Fusarium mycotoxins. Among others, T-2 toxin is the most acute toxic trichothecene. In this paper, adsorption of T-2 toxin by natural mineral adsorbents zeolite-clinop-tilolite and smectite minerals - bentonite and hectorite, at pH 3 was investigated. The highest adsorption index was achieved for hectorite (95%), while clinoptilolite and bentonite showed low adsorption index for T-2 toxin, 8% and 13%, respectively. Results of T-2 toxin adsorption on hectorite, at different amount of solid phase in suspension, and at pH 3, 7 and 9, showed that toxin adsorption indexes increased with increase of adsorbent concentration in suspension, at all investigated pH values. No significant differences in T-2 toxin adsorption by hectorite, at pH 3, 7 and 9 were observed.
The effects of zeolite and silica gel on synthesis of amylisobutyrate catalyzed by lipase from Candida rugosa
Authors: Stojakovic Sanja , Bezbradica Dejan , Mijin Dusan , Knezevic Zorica , Siler-Marinkovic Slavica
Published: July 2008

Lipase-catalyzed synthesis of esters has been widely investigated due to numerous advantages in comparison with the conventional chemical process catalyzed with concentrated acids since use of chemical catalysts leads to several problems. The most important disadvantages are corrosion of equipment, hazards of handling of the corrosive acids that are not reused, loss of conversion, yield and selectivity. The activity of water in reaction mixture seems to be one of the crucial factors affecting yield of enzymatic synthesis, since the excess of water promotes hydrolysis of the ester. Therefore, a significant part of related studies was focused on attempts to increase the yield of esters by efficient control of water activity. In our experimental work an attempt was made to regulate the activity of water by addition of water adsorbents in reaction mixture for synthesis of amyl isobutyrate. Two adsorbents were used: silica gel and molecular sieves (zeolites). The use of water adsorbents was optimized with respect to timing of adsorbent addition and pretreatment of adsorbent. The pretreatment of adsorbent with substrate did not increase the yield of ester. It was found that the timing of adsorbent addition is crucial factor. The addition in early phases of reaction leads to the decrease in ester yield compared to reaction without adsorbents. On the other hand, when the adsorbent was added in the late stage of reaction it exhibited beneficial influence on the yield of ester. The increase of yield was higher with silica gel (10%) than with molecular sieves (3.5%). These discrepancies can be ascribed to higher water adsorbing capacity of silica gel in systems with higher water content. Superior behavior of silica gel in ester synthesis in conjunction with simple process of regeneration recommends the use of this adsorbent for increasing the yield of lipase-catalyzed ester synthesis.
Comparation of fundamental analytical methods for quantitative determination of copper(II)ion
Authors: Acanski Marijana
Published: July 2008

Copper is a ductile metal with excellent electrical conductivity, and finds extensive use as an electrical conductor, heat conductor, as a building material, and as a component of various alloys. In this work accuracy of methods for quantitative determination (gravimetric and titrimetric methods of analysis) of copper(II) ion was studied. Gravimetric methods do not require a calibration or standardization step (as all other analytical procedures except coulometry do) because the results are calculated directly from the experimental data and molar masses. Thus, when only one or two samples are to be analyzed, a gravimetric procedure may be the method of choice because it involves less time and effort than a procedure that requires preparation of standards and calibration. In this work in gravimetric analysis the concentration of copper(II) ion is established through the measurement of a mass of CuSCN and CuO. Titrimetric methods is a process in which a standard reagent is added to a solution of an analyze until the reaction between the analyze and reagent is judged to be complete. In this work in titrimetric analysis the concentration of copper(II) ion is established through the measurement of a volume of different standard reagents: Km, Na2S2O3 and AgNO3. Results were discussed individually and mutually with the aspect of exactility, reproductivity and rapidity. Relative error was calculated for all methods.
The chemicals in laboratory have no appropriate quality
Authors: Petrovic Nevenka , Andjelic Brankica , Stankovic Suzana
Published: July 2008

Laboratory of Department for Chemical Technical Control (CTC) of the Mining and Metallurgy Institute has been accredited since January 2006. The ultimate intend of such laboratory is the international recognition of analyzing results. Due to a need of obeying all laws, regulations and standards, a description of one segment example, namely the quality of chemicals for analyzing was given in this work. Bad quality of chemicals is included into the "Black List of Chemicals". This List also includes chemicals, and comments of their bad quality.
Catalitic effect of Co on hydrogen desorption form nanostucturated magnesium hydride
Authors: Matovic Ljiljana , Milovanovic Snezana , Drvendzija Milica , Grbovic-Novakovic Jasmina
Published: July 2008

To study the influence of 3d transition metal addition on desorption kinetics of MgH2 ball milling of MgH2-Co blends was performed under Ar. Microstructural and morphological characterization, performed by XRD and SEM, show a huge correlation with thermal stability and hydrogen desorption properties investigated by DSC. A complex desorption behavior is correlated with the dispersion of the metal additive particles on hydride matrix. The activation energy for H2 desorption from MgH2-Co composite was calculated from both non-isothermal and isothermal methods to be 130 kJ/mol which means that mutually diffusion and nucleation and growth of new phase control the dehydration process.
The incorporation of Me-histidine complexes in the structure of FAU-type zeolite: Characterization of the obtained materials
Authors: Stosic Dusan , Damjanovic Ljiljana , Hercigonja Radmila , Dondur Vera , Rac Vladislav , Rakic Vesna
Published: July 2008

L-histidine, a naturally occurring amino acid, was incorporated inside the supercages of FAU type zeolite in a form of Me-complex entity (Me = Cu(II), Zn(II), Fe(III)). The preparation was done either by ion-exchange procedure, or previously prepared Me-histidine complex was incorporated into the a cages of Y zeolite by occlusion. The preparation procedure was found to be a very important factor, as well as the amount of metal complex loaded on the zeolite. The characterization of obtained samples was performed using Diffuse Reflectance Ultraviolet-Visible Spectroscopy (DRUV-Vis), 13C MAS NMR and Infrared Spectroscopy (FTIR). It was noticed that 1-hostidine interacted with the zeolitic framework, and with the extra-framework cation, as well. The results obtained by TG-DSC/MAS technique, revealed that the thermal stability of incorporated histidine was increased, in comparison with that one of pure histidine.
The influence of modification on structural, textural and adsorption properties of bentonite
Authors: Jovic-Jovicic Natasa , Milutinovic-Nikolic Aleksandra , Grzetic Ivan , Bankovic Predrag , Markovic Branislav , Jovanovic Dusan
Published: July 2008

Natural bentonite clay from the Bogovina locality in Serbia was Na-exchanged and modified using hexadecyll-trimethylammonium bromide as surfactant and organobentonite was obtained. The influence of modifications on the structural, textural and sorption properties of bentonite was investigated. It was estimated that modifications solely replace exchangeable cations in smectite layers, whereas other admixture minerals (quartz, calcite, feldspar) in bentonite remain unaffected. According to X-ray results the modification lead to changes in the smectite structure by either decreasing, for Na-bentonite, or increasing, for organobentonite, the interplanar spacing, JQOI- The appearance of three new bands in IR spectra of HDTMA-bentonite comparing to those of raw and Na-bentonite assigned to the methylene vibrations confirmed the embedding of aliphatic cations into smectite structure. In organobentonite a significant change in textural properties was observed. In particular, specific surface area dramatically decreased while originally meso and microporous material became almost completely non-porous. Despite almost insignificant specific surface area the synthesized organobentonite due to gained organophyllity of its surface exhibits exquisite adsorption properties toward investigated textile dyes having adsorption capacity approx. 2 times higher than activated carbon.
Investigation of medieval ceramics from Ras by physicochemical methods
Authors: Zindovic Natasa , Damjanovic Ljiljana , Holclajtner-Antunovic Ivanka , Mioc Ubavka , Bajuk-Bogdanovic Danica
Published: July 2008

Although early medieval Serbian ceramic is well described by the archeologists and historians, knowledge of the Balkan ceramic production is still limited. Archaeometric study of ceramics provenance, technology of preparation and used pigments as well as influence of neighboring countries and specific characteristics of different workshops has never been performed so far. The detailed knowledge of the micro-chemical and micro-structural nature of an archaeological artifact is critical in finding solutions to problems of restoration, conservation, dating and authentication in the art world. In this work we present results of systematic investigation of pottery shards from archeological site Ras. The term Ras, which signifies both the fortress and the region encompassing the upper course of Raska River, used to be the center of the medieval Serbian state. Both the ceramic body and the polychromatic glaze of the artifacts were studied by a multianalitical approach combining optical microscopy (OM), FT-IR spectroscopy and X-ray fluorescence (XRF). Mineralogical composition of pottery shards has been determined combining results obtained by FT-IR spectroscopy, after deconvolution of the spectra, and XRPD analysis. Firing temperature has been estimated based on the mineralogical composition and positions of Si-O stretching (-1000 cm-1) and banding (-460 cm-1) vibrations. Investigated samples have been classified into two groups based on the mineralogical composition, cross sections and firing temperature. Larger group consists of samples of fine-grained, homogeneous ceramics with firing temperatures bellow 800 ?C which indicates imported products. Second, smaller group consists of inhomogeneous ceramics with firing temperatures between 850 and 900 ?C produced in the domestic workshops. The obtained results will be used to build up a national database for the compositions of bodies, glazes and pigments.
Thermodynamic analysis of ternary system Ga-In-Sb
Authors: Gomidzelovic Lidija , Zivkovic Dragana , Mihajlovic Ivan
Published: July 2008

The results of thermodynamic analysis of ternary system Ga-In-Sb are presented in these work. Thermodynamic analysis was carried out by applying general solution predicting method in sections from Ga, In and Sb corner, respectively, with following ratios 1:3, 1:1, 3:1 in the temperature interval 873 to 1673 K. Based on this, excess molar Gibbs energies and activity of all components in specified temperature interval were calculated. Also, using the obtained data and MLAB software, ternary interaction parameters for Ga-In-Sb system were determined.
Influence of microstructure on the formability of Al-Mg6.8 alloy
Authors: Minov Boris , Popovic Miljana , Glisic Dragomir , Romhanji Endre
Published: July 2008

Formability of Al-Mg6.8 alloy has been evaluated experimentally in uniaxial tension and biaxial stretching. Three different structures developed after cold rolling and annealing in the range of temperature from 265 to 320 ?C: (I) recovered dual (a + ?) phase, (II) recrystallized (a + ?) dual phase, and (III) recrystallized a-Al single phase structure, were tested. Samples with recovered structure have shown a lower formability level than the samples with fully recrystallized structure. Formability level assessed through FLD and LDH value, has been a result of complex interaction between work hardening ability and strain rate sensitivity.