Gradual Loss of Partial Denture Retentive Forces

Djelomična proteza može se fiziološki ispravno prilagoditi fundamentu samo na osnovi poznavanja biostatike stomatognatoga sustava. Velik broj čimbenika utječe hoće li neka sila biti u funkciji fiziološke stimulacije ili će prouzročiti patološke promjene potpornoga tkiva. Ovim istraživanjem namjerava se utvrditi početna vrijednost retencijskih sila lijevanih kvačica, ankera i magneta, te njihov postupni gubitak sile nakon određenoga broja ciklusa vađenja i stavljanja retencijskih elemenata. Mjerenja su provedena u Zavodu za materijale Fakulteta za strojarstvo i brodogradnju Sveučilišta u Zagrebu. Ispitivani uzorci izrađeni su od materijala i gotovih elemenata prema podatcima proizvođača. Odgovaraju kriterijima koje zahtijeva DIN 13912 i DIN 13906-1 i ostalim internacionalnim standardima. Uređajem za mjerenje retencijske sile može se ciklički uključivati i isključivati retencijske elemente i kontinuirano prikupljati mjerne podatke. Ovim mjerenjima istraživao se postupni gubitak sila ispitivanih retncijskih elemenata. Dobivene vrijednosti kvalitativne raščlambe ispitivanih retencijskih elemenata prikazane su grafički i u tablicama. Tijekom ispitivanje došlo se do spoznaje da vrijednost retencijske sile kvačica i ankera postupno opada, a da se sila magnetskih slitina ne mijenja. Temeljni čimbenik koji bitno utječe na veličinu retencijske sile jest trošenje i zamor materijala. Spojnica uz nazočnost sline ima manju silu retencije, ali zbog smanjena trošenja nastat će i sporije smanjenje retencijske sile.A partial denture can be oppropriately accommodated physiologically on the denture base only with good understanding of the stomatognathic system biostatics. A force can either act as a physiological stimulus or can lead to pathological alterations in supporting tissue, wich depends on a great number of factors. The aim of the study was to determine the initial retentive force values of cast clasps, anchors and magnets as wel as their gradual loss of force after a certain number of retentive elements, extraction and insertion cycles. Measurement were carried out at the Materials Department, School Engineering and Naval Architecture, University of Zagreb. The examined specimens were made of materials and ready-made elements in accordance with the manufacturer’s declaration. They satisfy the DIN 13912 and DIN 13906-1 criteria and comply with other international standards. The device for retentive force measurement can periodically both include and exclude retentive elements thus continually collecting measurement data. Gradual loss of the examined retentive element forces was analysed by these measurings. The obtained values of the examined retentive elements qualitative analysis are presented in graphs and tables. In the course of analysis it was dicovered that the retentive force value of both clasps and anchors gradually decreases whereas the magnetic force of the alloys remains unchanged. The key factors which have a great impact on the retnetive force value are wear and material fatigue. A clasp in a wet environment (saliva) has less retentive force, but due to decreased wear the retnetive force decrease will progress more slowly

Maps of secular resonances in the NEO region

Context. From numerical simulations, it is known that some secular resonances may affect the motion of near-Earth objects (NEOs). However, the specific location of the secular resonance inside the NEO region is not fully known, because the methods previously used to predict their location can not be used for highly eccentric orbits and when the NEOs cross the orbits of the planets. Aims. In this paper, we aim to map the secular resonances with the planets from Venus to Saturn in the NEO region, even for high values of the eccentricity. Methods. We used an averaged semi-analytical model that can deal with orbit crossing singularities for the computation of the secular dynamics of NEOs, from which we can obtain suitable proper elements and proper frequencies. Then, we computed the proper frequencies over a uniform grid in the proper elements space. Secular resonances are thus located by the level curves corresponding to the proper frequencies of the planets. Results. We determined the location of the secular resonances with the planets from Venus to Saturn, showing that they appear well inside the NEO region. By using full numerical N-body simulations we also showed that the location predicted by our method is fairly accurate. Finally, we provided some indications about possible dynamical paths inside the NEO region, due to the presence of secular resonances.Comment: Accepted for publication in A&

Tehnike računarske inteligencije u modeliranju i identifikaciji indikatora ponašanja brane

Indikatori ponašanja brane su relevantne veličine, čijim se praćenjem utvrđuje da li je stvarno stanje brane u eksploataciji u saglasnosti sa onim što je predviđeno i očekivano u fazi projektovanja. Veličine koje se prate treba da se kreću u nekom unapred definisanom opsegu koji garantuje stanje stabilnosti brane. U ovoj disertaciji su predloženi različiti pristupi modeliranja i parametarske identifikacije indikatora ponašanja brane, poput horizontalnih pomeranja i nivoa vode u pijezometrima, tehnikama računarske inteligencije. Prvi pristup je da se linearno preslikavanje uzročnih veličina u indikatore ponašanja, koje se koristi kod višestruke linearne regresije, zameni nelinearnim. Drugi pristup, predložen u ovom radu, zasniva se na primeni postupka parametarske identifikacije nelinearnih sistema. Horizontalna pomeranja i nivoi vode u pijezometrima su nelinearne, složene funkcije uzročnih veličina, pa je za njihovo modeliranje korišćena NARX (Nonlinear Auto Regresive eXogenous- nelinearni auto-regresioni model sa spoljašnjim ulazom) struktura, kojom je opisana široka klasa nelinearnih dinamičkih procesa. Predloženi pristupi formiranja modela primenjeni su za modeliranje i parametarsku identifikaciju horizontalnih pomeranja tačaka brane Bočac, kao i nivoa vode u pijezometrima brana Đerdap II i Prvonek. Nelinearni modeli zasnovani na tehnikama računarske inteligencije implementirani su korišćenjem programskog jezika Java i programskog paketa Matlab. Tehnike računarske inteligencije korišćene u ovom radu su višeslojni perceptron, RBF (RBF - Radial Basis Function – radijalna osnovna funkcija) neuronska mreža i ANFIS (ANFIS - Adaptive-Network-Based Fuzzy Inference System - fazi sistem za zaključivanje zasnovan na adaptivnoj mreži). Nedostajući podaci u skupu merenja mogu biti uzrok problema u okviru procesa učenja i loših performansi dobijenih modela. U cilju nadomeštanja nedostajućih podataka korišćene su tehnike iz domena matematičke statistike. Prisustvo autlajera u mernim podacima ima veliki uticaj na predviđanja podataka koji nedostaju, pa je njihovo prisustvo posebno analizirano. Takođe je analiziran i problem optimizacije ulazno-izlaznih modela, koji podrazumeva određivanje broja prediktora i dimenzije regresionog vektora, kao i broja parametara neuronskih mreža i neuro-fazi sistema. Performanse modela, formiranih na osnovu predloženog koncepta, poređeni su sa rezultatima dobijenim drugim metodama modeliranja istih indikatora ponašanja prikazanim u relevantoj literaturi objavljenoj u poslednjih nekoliko godina. Na osnovu rezultata zaključeno je da je moguće kreirati i obučiti modele zasnovane na tehnikama računarske inteligencije koji će sa velikom preciznošću predviđati bitne indikatore ponašanja brane.The dam behavior indicators are relevant factors whose monitoring indicates whether the actual operational state of the dam is in accordance with what is expected and anticipated in the design phase. Such indicators should move in a predefined range, in order to guarantee stability of the dam. This dissertation proposes different approaches to modeling and parametric identification of the dam behavior indicators, such as radial displacements or piezometric water levels, using the techniques of artificial intelligence. The first approach is to replace linear mapping of causal variables into behavior indicators, which is used in multiple linear regression, with nonlinear. The second approach proposed in this paper is based on applying the method of parametric nonlinear system identification. Radial displacements and piezometric water levels are nonlinear, complex functions of causal variables, so for their modeling NARX (Nonlinear Auto Regresive eXogenous), which is employed to describe a wide class of nonlinear dynamic systems, is used. These proposed approaches are used for modeling and parametric identification of radial displacements of dam Bočac, and piezometric water levels of dams Iron Gate II and Prvonek. Nonlinear models based on artificial intelligence techniques have been implemented using the Java programming language and MATLAB. Artificial intelligence techniques used in this work are the multilayer perceptron, RBF (Radial Basis Function) neural network and ANFIS (Adaptive-Network-Based Fuzzy Inference System). The presence of missing data in a set of measurements may be causing problems in the learning process and the poor performance of the obtained models. In order to predict the missing data, the techniques of mathematical statistics have been used. Outliers present in a set of measurements have a big effect on the prediction of missing data, and their presence is specifically analyzed. The problem of optimizing the inputoutput model, which involves determining the number of predictors and dimensions of the regression vector, and the number of parameters of neural networks and neuro-fuzzy systems, is also analyzed. The performance of the models, formed on the basis of the proposed concept, are compared with those obtained by other methods of modeling the same behavioral indicators presented in relevant accompanying literature published in the last few years. Based on the results, it was concluded that it is possible to create and train models based on computational intelligence techniques to predict with great accuracy the essential dam behavior indicators

Supplementary data for the article: Dimitrijević, T.; Novaković, I.; Radanović, D.; Novaković, S. B.; Rodić, M. V.; Anđelković, K.; Šumar-Ristović, M. Synthesis, Spectral and Structural Characterization and Biological Activity of Cu(II) Complexes with 4-(Diethylamino)Salicylaldehyde and α-Diimines. Journal of Coordination Chemistry 2020, 73 (4), 702–716. https://doi.org/10.1080/00958972.2020.1740212

Supplementary material for: [https://doi.org/10.1080/00958972.2020.1740212]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/4025

The effect of the polyphenols of natural origin and the synthetic potassium channel openers on contractility of the isolated uterus

Prirodni polifenoli su zastupljeni u velikom broju biljnih vrsta. Kao posebni izvori rezveratrola moglo bi se izdvojiti grožđe i vino, kao njegov produkt, a naringenina grejpfrut, njegov sok, hmelj i pivo. Tokom poslednje decenije rezveratrol se našao u žiži naučne i šire javnosti kao supstanca koja usporava starenje, ima antikancerogena, antiinflamatorna, kardioprotektivna svojstva. Kao moguća mesta dejstva pokazan je veliki broj ćelijskih struktura, stoga je rezveratrol označen kao "jedan molekul - mnogo meta". Između ostalog, pokazano je da rezveratrol dovodi do relaksacije glatkih mišića mnogobrojnih krvnih sudova kao i glatkih mišića žučne kese. Kalijumovi kanali su direktno ili indirektno ukljućeni u mehanizam dejstva rezveratrola. Za razliku od njega, naringenin, pripada manje proučavanoj grupi, flavonoidima. Njegov mehanizam inhibicije kontrakcija glatkih mišića uterusa još uvek nije proučen. Pored velikog interesovanja za rezveratrol, njegov uticaj na kontraktilnost glatke muskulature uterusa nije izučavan. Stoga su ciljevi ove studije bili da ispitimo moguće inhibitorno dejstvo rezveratrola i naringenina na nekoliko eksperimentalnih modela negravidnog i gravidnog uterusa i da definišemo ulogu kalijumovih kanala u tim mehanizmima dejstva. Nepoželjna kontraktilnost uterusa je uzrok poremećaja kao što su dismenoreja, kod negravidnog, a prevremeni porođaj, kod gravidnog uterusa. Do danas, ni jedan od ovih problema nije farmakološki rešen. Dismenoreja se uglavnom tretira nesteroidnim antiinflamatornim lekovima, koji nisu uspešni kod svih pacijenata i imaju izrazite neželjene efekte. Dodatno, prevremeni porođaj je uzrok morbiditeta novorođenčati u 50 % slučajeva. Malo je dokaza da lekovi koji se koriste za suzbijanje prevremenih kontrakcija zaista efikasni. Prevremeni porođaj je češći i ozbiljniji problem u grupi pacijenkinja iz progrma in vitro oplodnje. Shodno tome, idealno sredstvo za prevenciju i lečenje neželjene kontraktilnosti uterusa još uvek nije pronađen..

The supramolecular arrangement in the Ni(II) complexes of isothiosemicarbazide

The molecules of two complexes [Ni(ITSC)2(H2O)2](tere)·2H2O and [Ni(ITSC)2(NO3)2] (ITSC = S-methylisothiosemicarbazide; tere = terephthalate) tend to associate trough the hydrogen bonding interactions into the characteristic 2D blocks separated by the S-methyl moieties. The different coordination mode of the isothiosemicarbazide comparing to thiosemicarbazide (TSC) prevents the formation of the complementary hydrogen bonds with dicarboxylate important for selfassambly of TSC complexes, however in these ITSC the terephthalate anion has role in connection of the blocks and transformation of the 2D into the 3D supramolecular structure. The similar crystal arrangement is found in two earlier reported complexes of Ni(II) with ITSC.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Comparison of two views regarding the nature of the X-H…phenyl interaction

There are two approaches in the analysis of the nature of the X-H…phenyl interactions. One is based on the assumption that atoms, bonds and the π plane belonging to the phenyl ring, are the points which can be involved in the interaction. The other states that center of the phenyl ring is the point acceptor. In this paper we compare two views using the directionality of the X-H vector and length/angle correlations relative to both assumed point acceptors. The results suggest that on the basis of this methodology there is no clear answer regarding the nature of the acceptor site in the phenyl ring.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Transition metal complexes with Girard reagents and their hydrazones

This is the first review dealing with the coordination chemistry of metal complexes with Girard's reagents and their hydrazones. The short introduction points out to chemical properties and significance of these organic compounds. The next section briefly describes synthetic methods for preparing complexes with Girard's reagents, as well as modes of coordination of these ligands. The last two extensive sections review the preparation, stereochemistry and structural characteristics of metal complexes with Girard's hydrazones, including some newer non-hydrazonic derivatives of Girard's reagents, also.[Acknowledgments. Projekat Ministarstva nauke Republike Srbije, br. 172014

3-Anilino-1-ferrocenylpropan-1-one

In the title ferrocene derivative, [Fe(C5H5)(C14H14NO)], the dihedral angle between the mean planes of the phenyl ring and the substituted cyclo­penta­dienyl ring is 84.4 (1)°. The mol­ecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing