Network theory approach for data evaluation in the dynamic force spectroscopy of biomolecular interactions

Investigations of molecular bonds between single molecules and molecular complexes by the dynamic force spectroscopy are subject to large fluctuations at nanoscale and possible other aspecific binding, which mask the experimental output. Big efforts are devoted to develop methods for effective selection of the relevant experimental data, before taking the quantitative analysis of bond parameters. Here we present a methodology which is based on the application of graph theory. The force-distance curves corresponding to repeated pulling events are mapped onto their correlation network (mathematical graph). On these graphs the groups of similar curves appear as topological modules, which are identified using the spectral analysis of graphs. We demonstrate the approach by analyzing a large ensemble of the force-distance curves measured on: ssDNA-ssDNA, peptide-RNA (system from HIV1), and peptide-Au surface. Within our data sets the methodology systematically separates subgroups of curves which are related to different intermolecular interactions and to spatial arrangements in which the molecules are brought together and/or pulling speeds. This demonstrates the sensitivity of the method to the spatial degrees of freedom, suggesting potential applications in the case of large molecular complexes and situations with multiple binding sites

Doping-induced quantum cross-over in Er2_2Ti2−x_{2-x}Snx_xO7_7

We present the results of the investigation of magnetic properties of the Er$_2$Ti$_{2-x}$Sn$_x$O$_7$ series. For small doping values the ordering temperature decreases linearly with $x$ while the moment configuration remains the same as in the $x = 0$ parent compound. Around $x = 1.7$ doping level we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time we present evidence of a long-range order (LRO) in Er$_2$Sn$_2$O$_7$ ($x = 2.0$) below $T_N = 130$ mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to $x = 0$. We discuss our results in the framework of a possible quantum phase transition occurring close to $x = 1.7$.Comment: accepted in PRB Rapi

Uticaj dodavanja organskog selena na proizvodne karakteristike fazana

The effect of organic selenium as feed additive contained in the feed was investigated, applied in concentrations of 0.3 and 0.4 mg Se/kg mixture on production characteristics pheasant. The study was conducted on a total of 45 common pheasant individuals Phasianus colchicus, six weeks old, divided into three equal groups of 15 individuals for 60 days. The control pheasants group was fed with a standard mixture without addition of selenium during the experiment, while the mixture of group I contained 0.15 g/kg and pheasants group II had 0.20 g/kg additives with organic selenium. The results showed that different amounts of organic selenium presence in pheasants' feed had a positive effect on analyzed productivity indicators of pheasants' growth rate, both their final body weight and weight gain (p (lt) 0.05). Among examined groups of pheasant, gained differences in average feed conversion and total production index were not statistically significant (p> 0.05). The best production results were achieved by individual II group, which also had the highest selenium content in muscle tissue of the pectoral muscles, drumstick and thigh (p (lt) 0.05).Na osnovu sprovedenih istraživanja može se zaključiti da je upotreba organskog selena kao dodatka smešama za ishranu fazana imala povoljan učinak na ispitivane proizvodne rezultate i sadržaj selena u mišićnom tkivu i jetri. Najbolje proizvodne rezultate je postigla II grupa fazana u čijoj hrani je upotrebljen organski selen u koncentraciji od 0,4 mg/kg. Nešto niže vrednosti proizvodnih pokazatelja su ostvarili fazani I grupe, čija je smeša sadržavala 0,3 mg/kg selena, dok su najniže vrednosti ispitivanih parametara ustanovljene u K grupi. Rezultati ovog istraživanja pokazuju da fazani osim statusa lovne divljači mogu imati veliki značaj u proizvodnji kvalitetnog mesa sa značajnim sadržajem antioksidanta selena koji bi doprineo prevenciji raznih oboljenja imunog sistema i poboljšanja zdravlja ljudi. Takođe, sa ekonomske tačke gledišta optimatizacijom smeša za ishranu fazana koje sadrže selen može se racionalizovati konverzija hrane i ujedno smanjiti troškovi ishrane

Copper production in Majdanpek in sixties and seventies of the 16th century

In this paper the practice of mine Majdanpek during sixties and seventies of the XVI century has been investigated with an accent on copper production. The attention has been also given to various subjects from considering copper treatment and use to forbidden activities connected to copper illegal production and trade with Persia

Proizvodnja i kvalitet mleka i mesa goveda i ovaca u uslovima održive proizvodnje

Basic principles that inform organic livestock production are reviewed in this paper, with special emphasis on milk and meat production in cattle and sheep. Research findings to date are presented on the impact of various management practices, both organic and conventional, as they effect product yield and quality. The importance of incorporating autochnochous breeds into organic milk and meat production systems is particularly emphasized. Additionally, a global overview of organic milk and meat production is given, along with an assessment of opportunities for implementing organic production systems in Serbia.U radu su prikazani osnovni principi organske proizvodnje u stočarstvu. Posebna pažnja posvećena je proizvodnji mleka i mesa goveda i ovaca. Prikazani su dosadašnji rezultati ispitivanja uticaja različitih uslova gajenja u organskoj i konvencionalnoj proizvodnji na prinos i kvalitet proizvoda. Istaknut je značaj korišćenja autohnonih rasa u organskoj proizvodnji mleka i mesa. Dat je prikaz organske proizvodnje mleka i mesa u svetu, kao i mogućnosti organizovanja organske proizvodnje u našoj zemlji

Supplementary data for the article: Izrael Živković, L. T.; Živković, L. S.; Beškoski, V. P.; Gopčević, K. R.; Jokić, B. M.; Radosavljević, D. S.; Karadžić, I. M. The Candida Rugosa Lipase Adsorbed onto Titania as Nano Biocatalyst with Improved Thermostability and Reuse Potential in Aqueous and Organic Media. Journal of Molecular Catalysis B: Enzymatic 2016, 133, S533–S542. https://doi.org/10.1016/j.molcatb.2017.06.001

Supplementary material for: [https://doi.org/10.1016/j.molcatb.2017.06.001]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/315]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3648

Candida rugosa lipase immobilized onto titania: improved thermal stability and reuse potential

Enzyme catalyzed reactions have been extensively exploited for a wide range of applications in biotechnology. In spite of a broad implementation of enzymes in different fields, some constraints referred to their cost and process stability still exists. To overcome a limit related to short catalytic lifetime of enzymes in process conditions, a spectrum of immobilization methods have been extensively studied to increase stability and enhance reuse, offer easier separation, making production economically viable.V International Conference on Radiation in Various Fields of Research : RAD 2017 : book of abstracts; June 12-16, 2017; Budva, Montenegr

Thermodynamics of a model for RNA folding

We analyze the thermodynamic properties of a simplified model for folded RNA molecules recently studied by G. Vernizzi, H. Orland, A. Zee (in {\it Phys. Rev. Lett.} {\bf 94} (2005) 168103). The model consists of a chain of one-flavor base molecules with a flexible backbone and all possible pairing interactions equally allowed. The spatial pseudoknot structure of the model can be efficiently studied by introducing a $N \times N$ hermitian random matrix model at each chain site, and associating Feynman diagrams of these models to spatial configurations of the molecules. We obtain an exact expression for the topological expansion of the partition function of the system. We calculate exact and asymptotic expressions for the free energy, specific heat, entanglement and chemical potential and study their behavior as a function of temperature. Our results are consistent with the interpretation of $1/N$ as being a measure of the concentration of $\rm{Mg}^{++}$ in solution.Comment: 11 pages, 4 figure

EKSTRAKCIJA I ANALIZA KONDENZIRANIH TANINA CASTANEA SATIVA MIIL.

Proanthocyanidins, also known as condensed tannins are widespread in woody plants, but are also found in certain forages. Castanea sativa Mill. are exploited for various purposes, but a little is known about potential of this species and possible application in diet and therapy. The parts of chestnut such as: seed, peeled seed, brown seed shell, red internal seed shell, leaves, catkin, spiny bur, as well as the new and old chestnut bark were extracted with 50% ethanol as an extragents. Contents of total phenolics and total flavonoids were measured by application of the standard colorimetric assay. The total condensed tannins content estimated was highest in red internal seed shell 15.29%CE (vanillin assay) and 3.12%CT (acid butanol assay). Also high content of total phenolic compounds and condensed tannins had extracts of catkin, brown seed shell of chestnut and new chestnut bark. Extracts of C. sativa Mill. can be a potential resource of natural tannins with possible application in diet and therapy.Proantocijanidini, poznati kao kondenzirani tanini su jako rasprostranjeni u drvenastim biljkama, a pronađeni su i u hrani. Castanea sativa Mill. se dosta koristi za različite namjene, međutim malo je poznat njegov potencijal i moguća primjena u dijeti i terapiji. Dijelovi kestena kao što su; cijeli plod, srž ploda, vanjska smeđa kora ploda, crvena unutrašnja kora ploda, list, resa, ježura, kao i nova i stara kora drveta su ekstrahirani primjenom 50% etanola kao ekstragensa. Sadržaj ukupnih fenola i flavonoida je određen primjenom standardnih kolorimetrijskih testova. Sadržaj ukupnih kondenziranih tanina je najviši u crvenoj unutrašnjoj kori 15,29%CE (vanilin test) i 3,12%CT (kiseli butanolni test). Visok sadržaj ukupnih fenolnih tvari i kondenziranih tanina je određen u ekstraktima rese, vanjske smeđe kore i nove kore drveta. Ekstrakti C. sativa Mill. mogu biti potencijalna sirovina koja sadrži prirodne tanine sa mogućom primjenom u dijeti i terapiji