COLLABORATIVE TESTING – IMPLICATIONS ON KNOWLEDGE RETENTION

Long-term monitoring of students’ achievements (5th to 8th grade, Branislav Nušić Primary School, Belgrade, Serbia) on Serbian Language and Computer Science tests, led authors to the conclusion that achievements, in most cases, are lower than expected. Test scores are inconsistent with the level of proficiency students are showing at school, during classes, when knowledge is not formally evaluated or is assessed in a different way. It is also noted that the knowledge that students demonstrate on tests usually does not keep. The lack of functional knowledge is confirmed by students’ weak achievements on the Primary School Final Exam.The authors have noticed that process of testing in both subjects causes discomfort in students, a decline of confidence, uncertainty and fear that they will not be successful enough. The authors have searched for a new type of testing that would have a positive impact on students’ achievements, prolong knowledge retention and provide the freedom of communication that encourage peer learning and encourage self-testing and auto-correction.The authors assumed that deficiencies of traditional testing could be overcome by introducing collaborative testing. Through action research, authors have concluded that collaborative testing contributes to the knowledge retention. Students achieve better results on tests. Testing becomes part of the learning process. The students are in a position to assess their knowledge and to act in order to advance. By developing the social aspects of education, progress of other students becomes one’s own progress, and responsibility is handed over to the learner at the fullest extent.&nbsp

Reproductive cycle in the common wall lizard (Podarcis muralis) from Belgrade

We studied male and female one-year reproductive, fat body and liver cycle of the common wall lizard (Podarcis muralis muralis) from the urban and suburban localities of Belgrade. The minimum size at which females attain sexual maturity was between 49.78 and 51.25 mm of the snout-vent length. Vitellogenesis started at the end of March. The size and number of vitellogenic follicles varied considerably during the season. Increase in the female size leads to a significant increase in number but not in size of vitellogenic follicles. Females with oviductal eggs were found from late May to late July. Two clutches with mean size of 3.5 ± 0.31 were laid in 1994. We found a significant positive correlation between female size and oviductal clutch size, while partial correlation between SVL and mean egg volume, as well as between clutch size and mean egg volume was insignificant. Relative oviductal clutch mass had the mean value of 0.17 ± 0.01, and was not correlated with female size. Testicles and epididymides exhibited maximal weight during April-June, and minimum in late July. The increase in male SVL lead to a significant increase in testicular and epididymal mass. Viable spermatozoa were produced from March to July. Fat bodies and liver of males were the smallest during the mating period while female fat bodies and liver decreased in weight during vitellogenesis. Mass of fat bodies and liver were significantly positively correlated with SVL in both sexes.U ovom radu je praćen jednogodišnji reproduktivni ciklus zidnog guštera (Podarcis muralis) na teritoriji grada Beograda. Minimalna veličina tela na kojoj ženke postaju polno zrele je bila između 49.78 i 51.25 mm. Vitelogeneza počinje krajem marta, dok broj i veličina vitelusnih folikula značajno varira tokom reproduktivne sezone. Veličina ženki je pozitivno korelisana sa brojem, ali ne i sa veličinom vitelusnih folikula. Ženke s oviduktalnim jajima su nalažene od kraja maja do kraja jula. Tokom ispitivane sezone 1994. godine postojala su dva legla, sa prosečnom veličinom od 3.50 ± 0.31 jaja. Ustanovljena je značajna pozitivna korelacija između veličine ženki i veličine legla, dok parcijalna korelacija između veličine ženki i prosečne zapremine jaja, kao i između veličine legla i prosečne zapremine jaja nije bila značajna. Prosečna relativna masa oviduktalnog legla je bila 0.17 ± 0.01 i nije bila u korelaciji sa veličinom tela ženki. Kod analiziranih mužjaka testisi i epididimisi su imali najveću masu u periodu april-juni, a najmanju krajem jula. Porast mase testisa i epididimisa je u direktnoj vezi sa veličinom tela mužjaka. Vijabilni spermatozoidi su nalaženi od marta do jula. Masa masnih tela i jetre kod mužjaka je bila najmanja u vreme parenja, dok se masa masnih tela kod ženki smanjivala tokom vitelogeneze. Značajna pozitivna korelacija između veličine tela i mase masnih tela i jetre je uočena kod oba pola.nul

Perovskite solar cells: Recent development and perspectives

Efikasnost konverzije energije hibridnih organsko-neorganskih perovskitnih solarnih ćelija (PSC) dostigla je vrednost uporedivu sa komercijalno dostupnim silicijumskim solarnim ćelijama. Glavni izazovi za njihovu komercijalizaciju su nestabilnost i toksičnost.The energy conversion efficiency of hybrid organic-inorganic perovskite solar cells (PSCs) has reached a value comparable to commercially available silicon solar cells. The main challenges for their commercialization are instability and toxicity

Reproductive cycle in the common wall lizard (Podarcis muralis) from Belgrade

We studied male and female one-year reproductive, fat body and liver cycle of the common wall lizard (Podarcis muralis muralis) from the urban and suburban localities of Belgrade. The minimum size at which females attain sexual maturity was between 49.78 and 51.25 mm of the snout-vent length. Vitellogenesis started at the end of March. The size and number of vitellogenic follicles varied considerably during the season. Increase in the female size leads to a significant increase in number but not in size of vitellogenic follicles. Females with oviductal eggs were found from late May to late July. Two clutches with mean size of 3.5 ± 0.31 were laid in 1994. We found a significant positive correlation between female size and oviductal clutch size, while partial correlation between SVL and mean egg volume, as well as between clutch size and mean egg volume was insignificant. Relative oviductal clutch mass had the mean value of 0.17 ± 0.01, and was not correlated with female size. Testicles and epididymides exhibited maximal weight during April-June, and minimum in late July. The increase in male SVL lead to a significant increase in testicular and epididymal mass. Viable spermatozoa were produced from March to July. Fat bodies and liver of males were the smallest during the mating period while female fat bodies and liver decreased in weight during vitellogenesis. Mass of fat bodies and liver were significantly positively correlated with SVL in both sexes.U ovom radu je praćen jednogodišnji reproduktivni ciklus zidnog guštera (Podarcis muralis) na teritoriji grada Beograda. Minimalna veličina tela na kojoj ženke postaju polno zrele je bila između 49.78 i 51.25 mm. Vitelogeneza počinje krajem marta, dok broj i veličina vitelusnih folikula značajno varira tokom reproduktivne sezone. Veličina ženki je pozitivno korelisana sa brojem, ali ne i sa veličinom vitelusnih folikula. Ženke s oviduktalnim jajima su nalažene od kraja maja do kraja jula. Tokom ispitivane sezone 1994. godine postojala su dva legla, sa prosečnom veličinom od 3.50 ± 0.31 jaja. Ustanovljena je značajna pozitivna korelacija između veličine ženki i veličine legla, dok parcijalna korelacija između veličine ženki i prosečne zapremine jaja, kao i između veličine legla i prosečne zapremine jaja nije bila značajna. Prosečna relativna masa oviduktalnog legla je bila 0.17 ± 0.01 i nije bila u korelaciji sa veličinom tela ženki. Kod analiziranih mužjaka testisi i epididimisi su imali najveću masu u periodu april-juni, a najmanju krajem jula. Porast mase testisa i epididimisa je u direktnoj vezi sa veličinom tela mužjaka. Vijabilni spermatozoidi su nalaženi od marta do jula. Masa masnih tela i jetre kod mužjaka je bila najmanja u vreme parenja, dok se masa masnih tela kod ženki smanjivala tokom vitelogeneze. Značajna pozitivna korelacija između veličine tela i mase masnih tela i jetre je uočena kod oba pola.nul

ZnO/RuO2 nanostructured composites with enhanced bifunctional photo-electro catalytic activity toward water splitting

The demand for affordable and accessible catalysts to replace the expensive and scarce resourced platinum group metals (PGMs) has become increasingly vital. Since they combine different properties such as electrochemical activities, chemical and photochemical stability, non-toxicity, etc. ZnO-based materials have been examined for potential applications in electronics, optoelectronics, sensing in environmental applications as well as catalysis. This study focused on cost reduction of PGM materials by introducing RuO2 as a substitute for Ru and decreasing the amount of RuO2 through the incorporation of abundant and versatile ZnO. A composite of ZnO/RuO2 in a 10:1 molar ratio was synthesized using a microwave processing of a prepcipitate. To enhance its catalytic properties, the composite was subsequently annealed at 300 and 600 C. The physicochemical characteristics of the ZnO/RuO2 composites were analyzed using X-ray powder diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Furthermore, the electrochemical activity of the samples was assessed through linear sweep voltammetry in both acidic (0.1 M H2SO4) and alkaline (0.1 M NaOH) electrolytes. Remarkably, the ZnO/RuO2 composites exhibited excellent bifunctional catalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both types of electrolytes

The importance of cross-reactivity in grass pollen allergy

According to the data obtained from in vivo and in vitro testing in Serbia, a significant number of patients have allergic symptoms caused by grass pollen. We examined the protein composition of grass pollens (Dactylis glomerata, Lolium perenne and Phleum pratense) and cross-reactivity in patients allergic to grass pollen from our region. The grass pollen allergen extract was characterized by SDS-PAGE, while cross-reactivity of single grass pollens was revealed by immunoblot analysis. A high degree of cross-reactivity was demonstrated for all three single pollens in the sera of allergic patients compared to the grass pollen extract mixture. Confirmation of the existence of cross-reactivity between different antigenic sources facilitates the use of monovalent vaccines, which are easier to standardize and at the same time prevent further sensitization of patients and reduces adverse reactions

ZnO@RuO2 composites: Cost-effective trifunctional electrocatalysts for enhanced OER, HER, and ORR activities in water electrolysis

Affordable catalysts for use in water electrolysis and fuel cells as clean energy sources pose a significant challenge. Currently, platinum group metal catalysts are both expensive and difficult to obtain. In this research, an attempt is made to address this issue by investigating methods to reduce costs. Specifically, the use of RuO2 instead of Ru and the incorporation of a substantial amount of easily available ZnO, which has various applications, are explored. A composite of ZnO@RuO2 in a 10:1 molar ratio was synthesized using microwave processing of a precipitate. To enhance its catalytic properties, the composite was subsequently annealed at 300 and 600 °C. A detailed analysis of the crystal structure, morphology, optical and (photo)electrocatalytic properties of the processed 10ZnO@RuO2 catalyst particles was conducted. The catalytic activity of the prepared composites toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 0.1 M NaOH and 0.1 M H2SO4 was investigated using linear sweep voltammetry (LSV). The measurements were taken both in the dark and under illumination after 60 minutes of exposure. To determine the intrinsic HER and OER activity of the studied catalyst, the LSV data were normalized by the electrochemical surface area (ECSA). Finally, the oxygen reduction reaction (ORR) activity of the catalysts was tested in both alkaline and acidic electrolytes

Karakterizacija Intor:Swiss soja albino miševa donetog u Institut za virusologiju, vakcine i serume - Torlak početkom XX veka

The Institute of Virology, Vaccines and Sera Torlak was established in 1927, while the first vaccine was produced in the Institute in 1930. Vaccines production implies using experimental animals, including mice, in in-process controls. The laboratory mice which have been in use in Torlak Institute from the very beginning belong to Swiss albino outbred stock. This stock, which has been in use for more than 80 years contains a large number of mice maintained at all times, was recently named Intor:Swiss. Biological characteristics of Intor:Swiss stock, are presented in this paper for the first time. Taking into account the presented characteristics, the Institute Torlak's Swiss mice are suitable for use in pharmaceutical studies, vaccine development research and basic research, as well as in toxicological studies. The publication of data on the Intor:Swiss mice represents a contribution to the international scientific community, since it offers the possibility for obtaining an additional outbred mouse stock for research.Institut za Virusologiju, vakcine i serume Torlak, osnovan je 1927., a prva vakcina u Institutu proizvedena je 1930. Proizvodnja vakcina je složen proces koji između ostalog podrazumeva i korišćenje eksperimentalnih životinja u kontroli samog procesa. Laboratorijski miševi koji su od samog početka bili u upotrebi u Institutu Torlak, pripadaju Swiss albino outbred soju. Ova kolonija je u upotrebi više od 80 godina i sve vreme se sastoji od velikog broja jedinki što omogućava očuvanje genetske raznolikosti, pa samim tim i outbred karakteristika. Ovi miševi su odnedavno registrovani pod imenom Intor:Swiss, i njihove biološke osobine su u ovom radu prikazane po prvi put. Swiss miševi Instituta Torlak pogodni su za upotrebu u farmaceutskim studijama, za razvojno istraživanje vakcina, osnovna istraživanja i toksikološka ispitivanja. Zbog svega navedenog Intor:Swiss miševi predstavljaju još jedan pogodan animalni model za ispitivanje lekova i vakcina

Voltammetric and theoretical studies of the electrochemical behavior of cephalosporins at a mercury electrode

The adsorption and electroreduction behavior of cefpodoxime proxetil, cefotaxime, desacetylcefotaxime, cefetamet, ceftriaxone, ceftazidime, and cefuroxime axetil at a mercury electrode surface were studied using cyclic (CV), differential pulse (DPV) and adsorptive stripping differential pulse (AdSDPV) voltammetry. The quantitative structure property relationship (QSPR) study of the seven cephalosporins adsorption at the mercury electrode was based on density functional theory DFT-B3LYP/6-31G(d,p) calculations of molecular orbitals, partial charges and electron densities of the analytes. The DFT-parameters and QSPR model explain well the process of adsorption of the examined cephalosporins. The QSPR study defined that cephalosporins with lower electron density on the nitrogen atom of the N-O bond, higher number of hydrogen bond-accepting groups, and higher principal moment of inertia should express high adsorption on the mercury electrode

Calculation of the fraction of pseudo-capacitance and electric double layer capacitance in carbon-based electrochemical capacitors.

Novi materijali za primenu u elektrohemijskim kondenzatorima razvijaju se u različitim pravcima: ugljenične nanocevi, grafen, aktivirani ugljenici, templirani porozni ugljenici, a sve sa ciljem poboljšanja njihovih karakteristika kroz povećanje kapaciteta dvojnog električnog sloja i/ili pseudokapacitivnih faradejskih procesa. Cilj ovog rada bio je određivanje kapaciteta za seriju ugljeničnih materijala metodom ciklične voltametrije pri različitim brzinama polarizacije, kao i razdvajanje doprinosa dvojnog električnog sloja i pseudokapacitivnosti ukupnoj vrednosti kapaciteta elektrohemijskih kondenzatora. Ispitivani materijali uključuju: karbonizovani nanostrukturni polianilin (C-PANI), karbonizovani polianilin dopiran 2,2-difenil-1-pikrilhidrazilom (C-DPPH) i aktivni ugalj (AC). Njihove karakteristike ispitane su u 6M KOH i 0,5M H2SO4, a kapacitivna svojstva pomenutih materijala uspešno su razdvojena primenom Trasatijeve (Trasatti) i Danove (Dunn) metode. Pokazano je da aktivni ugalj, bez obzira što nema najveću vrednost specifičnog kapaciteta u svim elektrolitima, ipak ima najveću retenciju kapaciteta i da bi bio najpogodniji za primenu kao elektrodni materijal u odnosu na ispitivane materijale.New materials for use in electrochemical capacitors are being developed in different directions: carbon nanotubes, graphene, activated carbon, templated porous carbon, all with the aim of improving their properties by increasing the capacitance of the double electric layer and/or pseudocapacitive faradaic processes. The aim of this work was to determine the capacitance of a series of carbon materials using cyclic voltammetry at different polarization rates, as well as to separate the contribution of the electric double layer capacitance and pseudo-capacitance to the total value of the capacitance. Materials that were tested include: carbonized nanostructured polyaniline (C-PANI), carbonated polyaniline doped with 2,2-diphenyl-1-picrylhydrazyl (C-DPPH) and activated carbon (AC). Their characteristics were tested in 6M KOH and 0.5M H2SO4, and the capacitance properties of the mentioned materials were successfully separated using Trasatti and Dunn methods. It has been shown that among the tested materials, activated carbon has the highest capacity retention, and it would be the best suited for use as electrode material, although it doesn't have the highest specific capacitance value in all electrolytes