Synthesis, characterization and selectivity of catalysts for hydrogenation of vegetable oils

U ovom radu proučavani su višekomponentni katalitički sistemi u kojima su aktivna komponenta (metalni Ni) i pogodni metali (Mg, Ag i Cu) naneseni na pripremljeni nosač (aktivirani dijatomit), kao i njihova primena u svojstvu katalizatora u procesu parcijalne hidrogenizacije jestivih biljnih ulja. Polazni materijal korišćen za sintezu nosača katalizatora predstavljao je sirovi dijatomit domaćeg porekla (ležište dijatomita Baroševac, istočni deo Kolubarskog ugljenog basena). Modifikacijom svojstava sirovog dijatomita hemijskom i termičkom obradom dobijen je nosač katalizatora sa visokim sadržajem silicijum dioksida. Ispitivanja teksturalnih svojstava i granulometrijskog sastava su pokazala da dijatomitni nosač ima makroporoznu strukturu i povoljan granulometrijski sastav, odgovarajući za dobijanje nikl katalizatora koji se koriste u procesima parcijalne hidrogenizacije biljnih ulja. Izvršena je sinteza nekoliko uzoraka katalizatora precipitacijom jedinjenja nikla i odgovarajućih metala iz vodenih rastvora njihovih nitratnih soli na pripremljeni dijatomitni nosač korišćenjem natrijum karbonata (PDI katalizatori) i uree (DPU katalizatori) u svojstvu precipitanta. Obavljeni su obimni eksperimenti koji su obuhvatili ispitivanja uticaja uslova sinteze prekursora PDI- i DPUNi/ D katalizatora na stepen redukcije. Proučavanjem uticaja SiO2/Ni molskog odnosa i brzine zagrevanja na stepen redukcije prekursora PDI-Ni/D katalizatora utvrđeno je da manji SiO2/Ni m.o. i manje brzine zagrevanja povećavaju stepen redukcije. Ispitivanja uticaja DP vremena na stepen redukcije prekursora DPU-Ni/D katalizatora su pokazala da kraća DP vremena omogućavaju veći stepen redukcije. Fizičko-hemijska svojstva prekursora PDI- i DPU-Ni/D katalizatora okarakterisana su primenom sledećih metoda: (1) standardna kvantitativna hemijska analiza; (2) rendgenostrukturna (XRD) i infracrvena (IR) spektroskopija; (3) Hg-porozimetrija i N2-fizisorpcija; (4) temperaturno-programirana redukcija (TPR); (5) H2-hemisorpcija; (6) skenirajuća elektronska mikroskopija (SEM) i energo disperziona spektroskopija (EDS); (7) difuziono-refleksiona spektroskopija ultravioletne i vidljive oblasti (DR UV-Vis); i (8) fotoelektronska spektroskopija X-zraka (XPS). Rezultati rendgenostrukturnih (XRD) ispitivanja neredukovanih prekursora PDI- i DPU-Ni/D katalizatora su pokazali da se pored Ni2+ faze baznog nikl karbonata (PDI-Ni/D prekursori) i turbostratičnog nikl hidroksida (DPU-Ni/D prekursori) u prekursorima nalaze i Ni hidrosilikati nastali interakcijom aktivnog metala i nosača. Analizom XRD difraktograma redukovano-pasiviziranih prekursora, kao i in situ XRD-H2 difraktograma određene su veličine kristalita aktivnog metalnog nikla i metala modifikatora (Ag). Utvrđeno je da su veličine kristalita nikla manje od veličine kristalita srebra. Rezultati ispitivanja neredukovanih prekursora Ni/D katalizatora infracrvenom spektroskopijom (IR) su potvrdili prisustvo Ni2+ faza baznog karbonata i hidrosilikata i ukazali da je distribucija obrazovane Ni2+ faze više usmerena prema Ni hidrosilikatima nego prema baznom Ni karbonatu (PDI-Ni/D prekursori). Pokazano je da kod DPU-Ni/D prekursora priroda DP Ni2+ faze zavisi od DP vremena. Rezultati ispitivanja porozne strukture neredukovanih prekursora katalizatora metodom Hg-porozimetrije su pokazali da su ukupna intruziona zapremina pora, zapremina makropora, srednji prečnik pora i ukupna poroznost prekursora manji nego kod dijatomitnog nosača usled popunjavanja pora nosača metalnim solima aktivnog metala i odgovarajućih metala modifikatora. Utvrđeno je da sa porastom sadržaja srebra dolazi do povećanja zapremine makropora...Multicomponent catalytic systems consisting of active component (metallic Ni) and appropriate metals (Mg, Ag, Cu) deposited onto a prepared support (activated diatomite) were investigated, as well as their application as catalysts in the process of partial hydrogenation of edible oils. Starting material used for the synthesis of the catalyst support was raw diatomite from domestic sources (Baroševac diatomite deposit, eastern zone of the Kolubara coal basin). Raw diatomite properties were modified through chemical and thermal treatment resulting in a catalyst support with high silicon oxide content. Investigation of the textural properties and granulometric composition showed that the obtained catalyst support has macroporous structure and convenient granulometric composition appropriate for the obtention of Ni containing catalysts for the partial hydrogenation of vegetable oils. Synthesis of several catalyst samples was performed by the precipitation of Ni compounds and appropriate metals from aqueous solutions of their nitrate salts onto the prepared diatomite support, using sodium carbonate (PDI catalysts) and urea (DPU catalysts) as precipitants. Thorough experiments were carried out in order to investigate the influence of the PDI- and DPU-Ni/D catalyst precursor synthesis conditions on the degree of reduction. Investigation of the influence of the SiO2/Ni molar ratio and heating rate on the degree of reduction of the PDI-Ni/D catalyst precursor showed that lower SiO2/Ni molar ratio and lower heating rate increase the reduction degree. Investigation of the dependence of the degree of reduction on the DP time indicated that shorter DP times enable higher reduction degree. Physico - chemical characterization of the PDI- and DPU-Ni/D catalyst precursors was performed using the following methods: (1) standard quantitative chemical analysis; (2) X-ray diffraction (XRD) and infrared (IR) spectroscopy; (3) Hg-porosimetry and N2-physisorption (4) temperature-programmed reduction (TPR); (5) H2-chemisorption; (6) scanning electron microscopy (SEM) and energy dispersed spectroscopy (EDS); (7) diffuse reflectance UV-Vis spectroscopy (DR UV-Vis); and (8) X-ray photoelectron spectroscopy (XPS). Results of the XRD analysis of non-reduced PDI- and DPU-Ni/D catalyst precursors showed that, beside Ni2+ phases in the form of basic nickel carbonate (PDI-Ni/D precursors) and turbostratic nickel hydroxide (DPU-Ni/D precursors), there are also Ni hydrosilicates, originating in the interaction between the active metal and catalyst support. Analysis of XRD diffractograms of the reduced and passivated precursors and in situ XRD-H2 diffractograms was used for the size determination of metallic nickel and modifier metal (Ag) crystallites. Results of the investigation of non-reduced precursors of the Ni/D catalysts using IR spectroscopy confirmed the presence of Ni2+ phases of basic carbonate and hydrosilicates and indicated that the Ni hydrosilicate phase prevail comparing to that of Ni carbonate (PDI-Ni/D precursors). It was shown that in the DPU-Ni/D catalyst precursors the nature of Ni2+ phase depends on the DP time..

Uticaj varijeteta višnje na hemijske i senzorne karakteristike rakije višnjevače

The chemical and sensorial characteristics of cherry brandy produced from five cherry varieties (Oblacinska, Celery's 16, Rexle, Heiman's Ruby and Heiman's Conserve) grown in Serbia were studied. Gas chromatography and gas chromatography-mass spectrometry analysis of these distillates led to the identification of 32 components, including 20 esters, benzaldehyde, 6 terpenes and 5 acids. The ethyl esters of C(8)-C(18) acids were the most abundant in all samples. The benzaldehyde content was quantified by high performance liquid chromatography with UV detection. The average benzaldehyde concentration in the samples ranged between 2.1 and 24.1 mg L(-1). The total sensory scores of the cherry brandies ranged between 17.30 to 18.05, with the cherry brandy produced from the Celery's 16 variety receiving the highest score (18.05).Ispitivane su hemijske i senzorske karakteristike rakije višnjevače proizvedene iz pet varijeteta višnje (Oblačinska, Celery's 16, Rexle, Heiman's Ruby i Heiman's Conserve) gajenih u Srbiji. Metodama gasne hromatografije i kombinacijom gasne hromatografije i masene spektrometrije u ekstrakatima identifikovana su 32 jedinjenja, 20 estara, benzaldehid, 6 terpena i 5 kiselina. Etil-estri C8-C18 kiselina su najobilniji u svim uzorcima. Sadržaj benzaldehida je određivan metodom tečne hromatografije uz UV detekciju. Prosečna količina benzaldehida u ispitivanim uzorcima bila je između 2,1 i 24,1 mg L-1. Ocene senzorskog ispitivanja rakija višnjevača su u rasponu od 17,30 do 18,05, dok je najbolje ocenjena (18,05) rakija proizvedena od varijeteta Celery's 16

DNK protektivna aktivnost triterpena izolovanih iz medicinske gljive Fomitopsis betulina

Eleven 31-methylenlanostane triterpenoids, i.e., seven 21- and four 26-oic acids, as well as a lupane triterpenoid betulin, isolated from the fruiting bodies of the mushroom Fomitopsis betulina, were tested for in vitro protective effect on chromosome aberrations in peripheral human lymphocytes using cytochalasin-B blocked micronucleus (CBMN) assay. Most of the tested compounds showed a beneficial effect by reducing DNA damage of human lymphocytes more effectively than amifostine, a radioprotective agent, used as a positive control. All the tested compounds decreased MN frequency in the concentration dependent manner, with the concentration of 2.0 µg mL-1 being the most effective – with increase of the concentration the activity slightly decreases. The structure–activity relationship (SAR) studies indicated that the lanostanes containing a conjugated 7,9 (11)-diene system exhibit lower activity than Δ8-analogues. It was also demonstrated that the DNA protective activities within the Δ8-lanostane-26-oic acid group are affected by the substitution in position 3 pattern. In the Δ8 series the oxygenation at C-12 or 16 as well as 21- or 26-oic acid functionality proved beneficial for in vitro protective effect on chromosomal aberrations. Betulin exhibited the lowest protective activity, but it is still comparable to that of amifostine.Једанаест 31-метиленланостанских тритерпеноида, то јест седам 21- и четири 26- ланостанских киселина, као и лупански тритерпеноид бетулин изолованих из плодонос- них тела гљиве Fomitopsis betulina тестирани су in vitro на заштитни ефекат на аберације хромозома у периферним хуманим лимфоцитима. Примењен је тест мерења учес- талости микронуклеуса индукованих применом инхибитора цитокинезе, цитохалазина Б. Испитивања су показала да већина тестираних једињења показује значајан протек- тивни ефекат на ДНК хуманих лимфоцита, већи него комерцијални радиопротективни агенс аминофостин. У опсегу концентрација 1, 2 и 4 μg mL-1 сва испитивана једињења су смањивала учесталост микронуклеуса (MN), при чему је најефиканија била концентра- ција од 2,0 μg mL-1. Са повећањем концентрације (4 μg mL-1) активност се благо смањује. Студије односа структуре и активности (SAR) показале су да ланостани који садрже кон- југовани 7,9-(11)-диенски систем имају нижу активност од _8-аналога. Такође је пока- зано да на заштитне активности ДНК унутар групе _8-ланостан-26-киселина утиче суп- ституција у положају 3. У _8-серији присуство кисеоничних функција на C-12 или C-16, као и C-21 или C-26 карбоксилних група повећава in vitro протективни ефекат на на ДНК хуманих лимфоцита. Међу испитиваним једињењима тритерпен бетулин (лупанска серија) је показао најмањи протективни ефекат сличан са протективним ефектом ами- фостина

Influence of forward scattering on prediction of temperature and radiation fields inside the pulverized coal furnace

Radiation is dominant mode of heat transfer in all types of combustion systems. Radiative heat transfer is described by radiative transfer equation, which indicates the importance of radiative properties of medium. Increase of radiation intensity due to emission of radiation is directly proportional to absorption coefficient of medium, and to scattering coefficient due to inscattering. In-scattering of radiation depends also on scattering phase function. Radiative properties of dispersed phase of pulverized coal flame are mainly determined by flyash particles, particle diameter of which is in the range from 0,1 to 50,0 μm. For particles of that size and for near infrared spectral interval, scattering phase function of single particle changes its form from almost isotropic to almost forward. Sensitivity of numerical simulations of pulverized coal furnaces to type of radiation scattering is the main objective of investigation. Tangentially fired dry bottom pulverized coal furnace of 210 MWe boiler has been chosen for numerical simulations. Numerical simulations have solved chemically reacting two phase particle gas flow with radiative heat transfer. Radiative heat transfer has been modelled using six-flux model. Radiative properties have been determined for absorbing, emitting and scattering medium. Scattering coefficients of the six-flux model have been determined for forward and isotropic scattering phase function. Grid indipendent results of numerical simulations have been obtained. Numerical simulations have been verified by comparison with results of measurements. Sensitivity of numerical simulations to type of radiation scattering has been investigated through comparison of temperature field, total radiation fluxes field, field of incident wall fluxes and absorbed heat by furnace walls. Although it has been shown that absorbed heat by furnace walls is bigger in case of isotropic scattering, result of investigation has shown that numerical simulations are almost insensitive to type of radiation scattering

Influence of forward scattering on prediction of temperature and radiation fields inside the pulverized coal furnace

Radiation is dominant mode of heat transfer in all types of combustion systems. Radiative heat transfer is described by radiative transfer equation, which indicates the importance of radiative properties of medium. Increase of radiation intensity due to emission of radiation is directly proportional to absorption coefficient of medium, and to scattering coefficient due to inscattering. In-scattering of radiation depends also on scattering phase function. Radiative properties of dispersed phase of pulverized coal flame are mainly determined by flyash particles, particle diameter of which is in the range from 0,1 to 50,0 μm. For particles of that size and for near infrared spectral interval, scattering phase function of single particle changes its form from almost isotropic to almost forward. Sensitivity of numerical simulations of pulverized coal furnaces to type of radiation scattering is the main objective of investigation. Tangentially fired dry bottom pulverized coal furnace of 210 MWe boiler has been chosen for numerical simulations. Numerical simulations have solved chemically reacting two phase particle gas flow with radiative heat transfer. Radiative heat transfer has been modelled using six-flux model. Radiative properties have been determined for absorbing, emitting and scattering medium. Scattering coefficients of the six-flux model have been determined for forward and isotropic scattering phase function. Grid indipendent results of numerical simulations have been obtained. Numerical simulations have been verified by comparison with results of measurements. Sensitivity of numerical simulations to type of radiation scattering has been investigated through comparison of temperature field, total radiation fluxes field, field of incident wall fluxes and absorbed heat by furnace walls. Although it has been shown that absorbed heat by furnace walls is bigger in case of isotropic scattering, result of investigation has shown that numerical simulations are almost insensitive to type of radiation scattering

Accumulation and seasonal variation of toxic and trace elements in tissues of Cyprinus carpio from semi-intensive aquaculture ponds

The aim of this study was to assess the accumulation and seasonal variations of 20 toxic and trace elements in the abdominal and dorsal muscle (DM), liver and gut contents (GCs) of Cyprinus carpio, and in the sediments and zooplankton from semi-intensive aquaculture ponds during a six-month production season (from May to October). Sediments showed the highest concentrations of the measured elements, followed by zooplankton, fish GCs and livers, while the lowest levels were present in fish muscles. Correspondence analysis revealed that the elemental composition of the fish GCs was mostly similar to that of the sediment and zooplankton. The element concentrations of carp liver and muscles were more similar to each other. Overall, the results indicate that fish liver was the main target organ accumulating Cu, Se and Zn, regardless of their initial amounts in the environment. A seasonal decrease of a range of elements in fish liver (Al, Co, Fe, Li, Mn, Ni, Pb and Sr) was evident towards the end of the investigation period. In addition, the fish DM showed a seasonal accumulation of Sr and Li. However, toxic elements i.e. As, B, Ba Hg and V did not show such a seasonal variation, and were evenly distributed between fish liver and muscles. The concentrations of some elements, such as As, in fish tissues were similar or even higher than in literature data from polluted sites, but none of them exceeded the maximum acceptable concentrations prescribed by Serbian legislation or by FAO or EU regulation

Deep Learning Based SWIR Object Detection in Long-Range Surveillance Systems: An Automated Cross-Spectral Approach

SWIR imaging bears considerable advantages over visible-light (color) and thermal images in certain challenging propagation conditions. Thus, the SWIR imaging channel is frequently used in multi-spectral imaging systems (MSIS) for long-range surveillance in combination with color and thermal imaging to improve the probability of correct operation in various day, night and climate conditions. Integration of deep-learning (DL)-based real-time object detection in MSIS enables an increase in efficient utilization for complex long-range surveillance solutions such as border or critical assets control. Unfortunately, a lack of datasets for DL-based object detection models training for the SWIR channel limits their performance. To overcome this, by using the MSIS setting we propose a new cross-spectral automatic data annotation methodology for SWIR channel training dataset creation, in which the visible-light channel provides a source for detecting object types and bounding boxes which are then transformed to the SWIR channel. A mathematical image transformation that overcomes differences between the SWIR and color channel and their image distortion effects for various magnifications are explained in detail. With the proposed cross-spectral methodology, the goal of the paper is to improve object detection in SWIR images captured in challenging outdoor scenes. Experimental tests for two object types (cars and persons) using a state-of-the-art YOLOX model demonstrate that retraining with the proposed automatic cross-spectrally created SWIR image dataset significantly improves average detection precision. We achieved excellent improvements in detection performance in various variants of the YOLOX model (nano, tiny and x)

Sinteza CaO nanešenog na Al2O3 od prekursora kalcujum acetata i njegova primena u transesterifikaciji suncokretovog ulja

Transesterification of sunflower oil was carried out over CaO loaded onto γ-Al2O3 as heterogeneous base catalysts. The solid base catalysts were syn­thesized by the modified wet impregnation of calcium acetate monohydrate onto neutral γ-Al2O3, calcined at different temperatures in an inert atmosphere and characterized by FESEM, XRPD and FTIR techniques. The catalyst con­taining 5.5 wt. % CaO supported on γ-Al2O3 calcined at 700°C exhibited the highest FAME yield at mild reaction conditions (60°C, atmospheric pressure, methanol-to-oil molar ratio of 9:1 and 0.51% of active species-CaO by weight of oil). The best CaO/γ-Al2O3 catalyst showed a similar or lower catalytic activity than some other CaO-based catalysts at a smaller amount of the catalyst (at least two times less than in other studies).Transesterifikacija jestivog suncokretovog ulja izvršena je korišćenjem CaO nanešenog na γ-Al2O3 kao heterogenog baznog katalizatora. Katalizator je si-ntetisan korišćenjem modifikovane metode mokre impregnacije gde je kalcijum acetat monohidrat kao precursor nanešen na neutralnu γ-Al2O3. Karakterizacija katalizatora je urađena korišćenjem sledećih metoda: FESEM, XRPD i FTIR. Na katalitičku aktivnost, a samim tim i prinos metil estara masnih kiselina, utiču morfologija i sastav katalizatora pripremljenog kalcinacijom na različitim temperatu­rama. U reakciji transesterifikacije suncokretovog ulja pri umerenim reakcionim uslovima (60°C, molski odnos metanola:ulja 9:1 i količina CaO 0,51% u odnosu na masu ulja) katalitički najaktivniji je katalizator sa 5,5 mas. % CaO nanešenih na nosač i kalcinisan na 700°C. U poređenju sa literaturnim rezultatima drugih katalizatora baziranih na CaO, primenjenim u sličnim reakcionim uslovima CaO/ γ-Al2O3 je pokazao sličnu ili nižu katalitičku aktivnost. Razlog tome je zato što je u ovom radu korišćena najmanje dva puta manja količina katalizatora po eksperimentu u odnosu na istraživanja sa kojima je vršeno poređenje

Joined statistical – thermodynamic expression for entropy and Hook’s law in the analysis of states of elongated ligament biostructure

Analytic joined statistical - thermodynamic expression for entropy as a function of state for measuring disorder of the corresponding micro state and the mechanical parameters which feature in Hooke’s law on elasticity as a measure of macro state was used in the situation of isothermal elongation of viscoelastic ligament biostructure simultaneously with external force of constant intensity to determine the change of entropy and the resultant reactive elastic force in the function of relative elongation. The sample used for the analysis and testing of the original joined theory shown with adequate equations is tested on linear biostructure approximating the data of Lig. collatelare fibulare which strengthens the lateral side of the knee joint. The obtained results for the tested linear biostructure according to which the minimal value of the difference in dS corresponds to the state of maximal entropy and the minimal value of elastic force indicates the acceptable level of elongation at which a reversible process is still possible, with low probability. This leads to the conclusion that, according to the results obtained here, the biostructure under examination can withstand the elongation which is approximately equal to twice the initial length L0. The relation between the friction force Ftr and the elasticity force Fe for the initial state is 1.0417, which indicates that the friction force is to a certain extent higher than the elastic force. With elongation this ratio changes in favour of the friction force and becomes more prominent with advanced age

Calcium oxide as a promising heterogeneous catalyst for biodiesel production: Current state and perspectives

The present paper is an overview of the recent progress in the development of various CaO-based catalysts suitable for biodiesel production. The mechanism, kinetics and optimization of transesterification reaction over these catalysts are first considered. Then, the practical application of CaO-based catalysts is discussed with a special stress on leaching and reusability of these catalysts. Also, various continuous reactor systems currently in use for biodiesel production are appraised. In addition to it, purification of crude biodiesel and the ecological aspects of using CaO-based catalysts are considered. Finally, the potentials of CaO-based catalysts for heterogeneous catalysis for biodiesel production are emphasized to assess the future perspectives of their use. This review might help in selecting suitable CaO-based catalysts and the optimum reaction conditions for biodiesel production