Ispitivanje kinetike sušenja krompira u laboratorijskim uslovima

Chemistry is in its nature a fundamental science, but nowadays its results are increasingly used in practice. In such a way, many syntheses of important nutrition and industrial compounds (chemical technology), or destruction of harmful substances (chemical ecology) have been developed. The analytic part of chemistry (analytical chemistry) has found a significant usage even in optimization of technological processes of food technology. One of the oldest ways of food preservation is drying (dehydration). The basis of this process of preservation is to vaporize water, to dry enough the product, in order to stop the activity of enzymes and possibility of microorganisms’ development. Water in agricultural products is not free but bound to dry matter. Therefore, for its vaporizing it is necessary to bring enough heat. The part of the brought heat is used for vaporizing water, but one part of it becomes the energy for activation of several chemical reactions that decrease the nutritive values and the quality of future food. Therefore, the important engineering problem emerges: determination of optimal conditions for drying. For optimization of technological process of drying, it is necessary to do mathematical modeling of dependence of water vaporizing speed from environmental conditions beforehand. The aim of this paper is to determine potato pieces drying kinetics in laboratory dryer, in order to determine the optimal conditions for its industrial dehydration. It was established that in the first quarter of the time of drying evaporated 28.3% of total evaporation of water, and then in order by quarters: 53%, 14.1% and 4.6%, respectively. The greatest speed of drying was realized at moisture of potatoes about 50%.Hemija jeste, po svojoj prirodi, fundamentalna nauka, ali su danas njena saznanja sve više primenjena u praksi. Tako su razvijene mnoge sinteze važnih prehrambenih i industrijskih jedinjenja (hemijska tehnologija), ili razgradnja štetnih supstanci (hemijska ekologija). Analitički deo hemije (analitička hemija) našla je značajnu primenu čak i u optimizaciji tehnoloških postupaka tehnologije hrane. Jedan od najstarijih načina konzervisanja namirnica je sušenje (dehidracija). Osnova ovog postupka konzervisanja je da se voda ispari, da se proizvod dovoljno isuši, kako bi se sprečila aktivnost enzima i mogućnost razvoja mikroorganizama. Voda u poljoprivrednim proizvodima nije slobodna već je vezana za suvu materiju. Zato je za njeno isparavanje potrebno dovesti dovoljno toplote. Deo dovedene toplote se koristi za isparavanje vode, ali jedan njen deo postaje energija aktivacije za niz hemijskih reakcija koje umanjuju nutritivnu vrednost i kvalitet buduće hrane. Stoga se postavlja važan inženjerski problem: odrediti optimalne uslove sušenja. Za optimizaciju tehnološkog postupka sušenja neophodno je prethodno izvršiti matematičko modeliranje zavisnosti brzine isparavanja vode od uslova sredine. Cilj ovog rada je da utvrdi kinetiku sušenja komada krompira u laboratorijskoj sušari, kako bi se zatim utvrdili optimalni uslovi za njegovu industrijsku dehidraciju. Utvrđeno je da u prvoj četvrtini vremena sušenja ispari 28,3% ukupno isparene vode, a zatim redom po četvrtinama: 53%, 14,1% i 4,6%. Najveća brzina sušenja ostvarena je pri vlažnosti krompira od oko 50%

Kinetika sušenja i kvalitet jabuke sorti Granny Smith, Idared i Jonagold

Apple is nutritionally valuable and present as fresh fruit in human nutrition throughout the year. Also apple is a raw material in food processing, primarily in the production of juices, nectars, refreshing soft drinks, marmalades, jams, compotes, apple cider vinegar and dried fruits. In the last decade on the world market there is a great interest in dried apple products (commercially called apple chips). During preservation by drying the technological process aimed at the final product of optimal quality is required. The subject of this paper is the kinetics of the apple cv. Granny Smith, cv. Idared and cv. Jonagold drying in laboratory dehydrator for the purpose of pinpointing at which level of humidity the maximum speed of evaporation is achieved and at which level of humidity apple slices begin to change in colour and geometric shape. Parameters of the drying process were the same for all three cultivars, 3hrs at air temperature of 70oC and 5hrs at air temperature of 50o. The amount of evaporated water is expressed in relative and absolute units of measure. The purpose of this paper is to determine which one of the three tested cultivars provides the best properties for drying, i.e. in terms of oxidation of polyphenolic compounds to find the cultivar which will provide that the final product is technologically and organoleptically the most acceptable. The results showed that the sample cv. Granny Smith expressed the least oxidation of polyphenolic compounds (browning), curved edges and shrivelled apple slices. After that the sample cv. Jonagold followed. The sample cv. Idared showed the worst results. Following the drying kinetics of all three samples, it can be concluded that the cultivars Granny Smith and Jonagold were achieving the lower maximum speed of evaporation, unlike the cultivar Idared. The cultivars Granny Smith and Jonagold have attained consistent drying and in this way the technological process was finished with a smaller temperature stress for plant tissue, resulting in a much better quality of the final product.Nutritivno vredni plodovi jabuke se koriste kao stono voće tokom cele godine, ali i kao sirovina u prehrambenoj industriji za proizvodnju sokova, nektara, osvežavajućih bezalkoholnih pića, marmelada, džemova, kompota, jabukovog sirćeta i sušenih plodova. Poslednjih decenija na svetskom tržištu postoji veliko interesovanje za sušene proizvode od jabuke (marketinški nazvane čips od jabuke). Pri konzervisanju sušenjem od tehnološkog postupka se zahteva da obezbedi gotov proizvod optimalnog kvaliteta. U radu je izučavana kinetika sušenja jabuke sorti Granny Smith, Idared i Jonagold u laboratorijskom dehidratoru sa ciljem da se uoči pri kojim sadržajima vlage dolazi do postizanja maksimalne brzine isparavanja i pri kojoj vlažnosti kolutovi jabuke počinju da menjaju boju i geometrijski oblik. Parametri procesa sušenja su isti za sve tri sorte, 3 h na temperaturi vazduha od 70oC i 5 h na temperaturi vazduha od 50oC. Količina isparene vode je izražena u relativnim i apsolutnim jedinicama mere. Cilj rada je da se utvrdi koja od ispitivane tri sorte pruža najbolje mogućnosti za sušenje, tj. da se sa aspekta oksidacije polifenolnih jedinjenja pronađe sorta koja omogućava da gotov proizvod bude tehnološki i organoleptički najprihvatljiviji. Rezultati su pokazali da je uzorak sorte Granny Smith pored najmanje izražene oksidacije polifenolnih jedinjenja (tamnjenje) imao i najmanje izraženo povijanje ivica i smežuravanje kolutova, potom sledi sorta Jonagold, a najlošije rezultate je pokazao uzorak sorte Idared. Prateći kinetiku sušenja sva tri uzorka zaključuje se da su sorte Granny Smith i Jonagold postigle manje maksimalne brzine isparavanja, za razliku od sorte Idared. Sorte Granny Smith i Jonagold su imale ravnomerno sušenje i na taj način tehnološki postupak se vršio sa manjim temperaturnim stresom za biljno tkivo što je rezultiralo mnogo boljim kvalitetom gotovog proizvoda

Environmental sustainability and corporate social responsibility of business schools: is there evidence of transdisciplinary effects?

This study analyses the relationship of environmental sustainability and the corporate social responsibility (CSR) of business schools by using the partial least squares structural equation modelling (PLS-SEM) empirical approach on a sample of 338 students from South East Europe. In support of the extant theory of responsible management education, emphasizing the transdisciplinary relationship between the Ethics, CSR, and Sustainability (ERS) domains, we found a direct relationship between environmental sustainability and CSR of business schools. However, we empirically verified a path of indirect effects at the institutional level, starting with the idealism of individual students, leading to the CSR institutional involvement of a business school, mediated by its environmental involvement. Provided that the idealistic individuals might be driving the functioning of the individual responsible management education and its domains, we propose the existence of a potential halo effect (’ERS halo effect’), which has already been described and verified in the corporate sector. We believe that its dynamics, based on the biased assessment of a single business school ERS domain, with its outcomes reflected in the other domains, should be further explored in different institutional and cultural environments

Odnos dužine strane prema dužini pomoćne baze u paralaktičkoj poligonometriji

Odnos dužine strane prema dužini pomoćne baze u paralaktičkoj poligonometriji

Differential activation of JNK in rat hippocampus following acute and/or chronic stressors.

c-Jun N-terminal kinase (JNK) is activated by phosporylation in response to cellular stressors and extracellular signals and plays a role in the activation of glucocorticoid receptor (GR) and contributes to the stress-induced apoptosis. Therefore, the expression protein pattern of the active forms of cytosolic phospho- JNK (P-JNK) and inactive JNK in hippocampus of rats exposed to 21daily isolation as chronic stressor, sole and in combination with 2hrs acute stressors of immobilization (IM) or cold (4oC), were followed by Western blot. Concentration of serum corticosterone was monitored. We found significant increase in the levels of P-JNK following acute IM. Decreased levels of P-JNK following chronic isolation and when isolation preceded the application of acute IM were found, compared to its level after acute IM. Data suggest that diminished expresion of PJNK level following chronic isolation in hippocampus, might be involved in deregulation of intracellular GR negative feedback control as well as stress-induced apoptosis.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Typology of humor in Serbia oral prose

Студија Типологија хумора у српској усменој прози бави се комплексним феноменом хумора, указујући на његову обредну, историјско-цивилизацијску, социо- психолошку, културолошку и естетску димензију. Основ хумора (комичног и смешног) анализира се у обредном и магијском контексту и у вези с природом и људском потребом да њоме овлада. Такође, и у контексту савременог живота у којем комично означава и црнохуморну (трагикомичну), апсурдну визију света, која га и удаљава од његових првобитних обредно-магијских корена. Проблем који се намеће односи се на дефинисање појма хумора у теоријско- методолошком смислу, јер постоје знатне разлике у приступима и научним тумачењима. У овој студији хумор се карактерише као општа категорија у оквиру које комично и смешно представљају елементе његовог естетског и појавног изражавања, при чему се сва три појма користе без значајних значењских дистинкција...The paper Typology of humor in Serbian oral prose deals with complex phenomenon of humor, pointing to its ritual, historical and civilizational, sociopsyhological, cultural and aesthetic dimension. The basis of humor ( comic and funny ) is analysed in ritual and magical context and it is connected with nature and people need to master it. In context of modern life in which comic means black comedy (tragycomic), absurd vision of the world, which moves him away from his original ritual and magical roots. Problem that arises refers to the definition of the term humor in theoretical and methodology sense, because there are significant differences in approaches and scientific interpretations.In this paper humor is characterized as a general category in which comic and funny represent elements of its aesthetical expression and manifestation, all three terms being used without significant semantic distinctions..

Phenomenon of Transparency: Cityscape Transformations Mapping Research Issues

The aim of this article is to propose methodological layers, developed during PhD research, which explore the impact of transparency in relation to the transformations of the city. First two parts of the process investigate the impact of transparency by decoding (in) visible cityscape transformations, towards mapping the fragments of intersections between individual atmospheres. After merging static and dynamic activity states of the phenomenon of transparency, the fourth layer shifts perception by zooming in and out – from the city as a whole, towards its individual spatial values and specific aspects. Analysis ends with (de)fragmentation reading via drawing as a critical tool for resolving spatial conflicts. Layer by layer, the proposed methodology determines the influence of the phenomenon of transparency on architectural design process, and its importance for rethinking and understanding the problems and potentials of cityscape transformations