Growth of Sb2S3 Nanowires Synthesized by Colloidal Process and Self-Assembly of Amorphous Spherical Sb2S3 Nanoparticles in Wires Formation

Ivana Lj. Validži,Nadica D. Abazovi,Miodrag Mitric 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.6

We report the organic synthesis and growth of antimony sulfide (Sb2S3) amorphous nanospheres to nanowires via a simple, colloidal synthetic method. Amorphous Sb2S3 nanospheres self-assembly in wires formation was dispersed in isopropyl alcohol. With increased heating time, Sb2S3 nanospheres grew into Sb2S3nanowires, probably involving both mechanisms of Ostwald-ripening and spherical nanoparticle self-organization through oriented-attachment of individual nanoparticles. Also, the as-synthesized Sb2S3 nanowires with different heating times (0, 5 and 10 min.) from the moment of appearance of the Sb2S3 precipitate were analyzed. The observed nanowires become longer with increased heating time and are around 100nm in diameter and 10-20 μm in length. UV-Vis absorption spectroscopy reveals that the optical band-gap energy of the Sb2S3 nanowires is independent of the heating times and is found to be ~1.5-1.6 eV. The optical band-gap energy found for amorphous Sb2S3 nanospheres was also ~1.5 eV. The structure of Sb2S3samples was refined down to R-factors of 10.82, 11.76 and 12.08%. The refinement showed that Sb2S3powder belongs to the orthorhombic type with space group Pbnm (no. 62) and that Sb2S3 nanowires grow along the [010] direction.

pH-Sensitive Hydrogels Based on (Meth)Acrylates and Itaconic Acid

Simonida Lj. Tomić,Marija M. Babić,Katarina M. Antić,Jovana S. Jovašević Vuković,Neda B. Malešić,Jovanka M. Filipović 한국고분자학회 2014 Macromolecular Research Vol.22 No.11

Novel hydrogels based on 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and different poly(alkylene glycol) (meth)acrylates (PAGM) (P(HEMA/IA/PAGM)) were synthesized. We investigated the influenceof different PAGM components, with acrylic or methacrylic acid residues in the main chain and ethylene glycol (EG)and/or propylene glycol (PG) units in pendant chains of varying length, on the nature and inherent properties ofP(HEMA/IA/PAGM) copolymeric hydrogels. Swelling studies revealed pH sensitive behavior of P(HEMA/IA/PAGM)samples. Hydrogel structure and morphology were characterized by Fourier transform infrared (FTIR) spectroscopyand scanning electron microscopy (SEM), which confirmed their chemical structure and differences in pore size. The shear modulus values for P(HEMA/IA/PAGM) hydrogels were close to that of PHEMA, but slightly lower thanthe value for P(HEMA/IA). Cephalexin (CEX) drug release profiles from P(HEMA/IA/PAGM) samples showed amarked dependence on the PAGM component. The presence of IA also influenced the release rate of CEX, leadingto a faster release when IA was combined with the more hydrophilic PAGM component. An in vitro assay of P(HEMA/IA/PAGM) cytotoxicity showed good cell viability. The results obtained indicate that P(HEMA/IA/PAGM) hydrogelproperties were significantly dependent on the PAGM component, meaning that the type of side chains can be usedto tune the characteristics of such biomaterials. These properties make P(HEMA/IA/PAGM) copolymeric hydrogelsapplicable in biomedical and biotechnological fields and controlled drug delivery.

HADAMARD AND DRAGOMIR-AGARWAL INEQUALITIES, HIGHER-ORDER CONVEXITY AND THE EULER FORMULA

Dedic, Lj.,Pearce, C.E.M.,Pecaric, J. Korean Mathematical Society 2001 대한수학회지 Vol.38 No.6

We obtain bounds relating to Eulers formula for the case of a function with higher-order convexity properties. These are used to derive estimates of the error involved in the use of the trapezoidal formula for integrating such a function.

Accuracy of incidental dynamic analysis of mobile elevating work platforms

Miomir LJ. Jovanović,Goran N. Radoičić,Vladimir S. Stojanović 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.5

This paper presents the results of a study into the dynamic behaviour of a support structure of a mobile elevating work platform. The vibrations of the mechanical system of the observed structure are examined analytically, numerically, and experimentally. Within the analytical examination, a simple mathematical model is developed to describe free and forced vibrations. The dynamic analysis of the mechanical system is conducted using a discrete dynamic model with a reduced number of vibrational degrees of freedom. On the basis of the expression for the system energy, and by applying Lagrange's equations of the second kind, differential equations are derived for system vibrations, frequencies are determined, and the laws of forced platform vibration are established. At the same time, a nonlinear FEM model is developed and the laws of free and forced vibration are determined. The experimental and numerical part of the study deal with the examination of the real structure in extreme conditions, taking into account: the lowest eigenfrequency, forced actions that could endanger the general stability, the maximal amplitudes, and the acceleration of the work platform. The obtained analytical and numerical results are compared with the experiments. The experimental verification points to the adverse behaviour of the platform in excitation cases – swaying. In such a situation, even a relatively small physical force can lead to unacceptably high amplitudes of displacement and acceleration – exceeding the usual work values.

Effect of Radial Head Prostheses Design on Radiocapitellar Joint Stability

문준규,LJ Berglund,Z Domire,KN An,SW O’Driscoll 대한견주관절의학회 2009 대한견주관절학회 학술대회논문집 Vol.2009 No.5

Some common fixed point theorems for weakly compatible mappings

Ć,irić,, Lj.B.,Ume, J.S. Elsevier 2006 Journal of mathematical analysis and applications Vol.314 No.2

<P><B>Abstract</B></P><P>Jungck's [G. Jungck, Compatible mappings and common fixed points, Int. J. Math. Math. Sci. 9 (1986) 771–779] notion of compatible mappings is further extended and used to prove some common fixed point theorems for weakly compatible non-self mappings in complete convex metric spaces. We improve on the method of proof used by Rhoades [B.E. Rhoades, A fixed point theorem for non-self set-valued mappings, Int. J. Math. Math. Sci. 20 (1997) 9–12] and Ahmed and Rhoades [A. Ahmed, B.E. Rhoades, Some common fixed point theorems for compatible mappings, Indian J. Pure Appl. Math. 32 (2001) 1247–1254] and obtain generalization of some known results. In particular, a theorem by Rhoades [B.E. Rhoades, A fixed point theorem for non-self set-valued mappings, Int. J. Math. Math. Sci. 20 (1997) 9–12] is generalized and improved.</P>

Finite-time Stability for a Linear Discrete-time Delay Systems by using Discrete Convolution: an LMI Approach

Sreten B. Stojanovic,Dragutin Lj. Debeljkovic,Milan A. Misic 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.4

The problem of finite-time stability for a class of linear discrete-time systems with state delay is studied. The Lyapunov-Krasovskii-like functional which is based on discrete convolutions of delayed state vector andtime-dependent discrete vector functions is used. In order to obtain much less conservative results, new sufficientcondition is derived in form of linear matrix inequalities. Numerical example is given to demonstrate the effectivenessof the proposed stability criterion. It was shown that the obtained results are less conservative than someexisting ones in the literature. A computer simulation was performed for the analysis of the dynamical behaviourof this system.

Rheology of alumina suspensions stabilized with Tiron

J. J. Gulicovski,Lj. S. Cerovic,S. K. Milonjic 한국유변학회 2008 Korea-Australia rheology journal Vol.20 No.2

Pressure filtration technique was used to obtain defect-free microstructure of green cast ceramic bodies. Stable alumina suspensions of desired rheology (<5 Pa s at 1 s-¹) containing 60 - 80 mass. % solid loading were prepared in the alkaline region (at pH~9) with an optimum amount of 0.5 dmb % of Tiron added. Acidic region (at pH 4) enabled the preparation of 60 mass. % suspensions with addition of 1.5 dmb % of Tiron. The best quality slip was processed from an 80 mass.% suspension with 63% of theoretical density. The homogeneity of particle packing and the absence of defects in microstructure were proven by narrow pore size distribution (ranging from 32 to 64 nm, with up to 85% abundance), confirming advantages of the wet consolidation route.

Non-linear incidental dynamics of frame structures

Goran N. Radoičić,Miomir LJ. Jovanović,Dragan Z. Marinković 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.6

A simulation of failures on responsible elements is only one form of the extreme structural behavior analysis. By understanding the dynamic behavior in incidental situations, it is possible to make a special structural design from the point of the largest axial force, stress and redundancy. The numerical realization of one such simulation analysis was performed using FEM in this paper. The boundary parameters of transient analysis, such as overall structural damping coefficient, load accelerations, time of load fall and internal forces in the responsible structural elements, were determined on the basis of the dynamic experimental parameters. The structure eigenfrequencies were determined in modal analysis. In the study, the basic incidental models were set. The models were identified by many years of monitoring incidental situations and the most frequent human errors in work with heavy structures. The combined load models of structure are defined in the paper since the incidents simply arise as consequences of cumulative errors and failures. A feature of a combined model is that the single incident causes the next incident (consecutive timing) as well as that other simple dynamic actions are simultaneous. The structure was observed in three typical load positions taken from the crane passport (range-load). The obtained dynamic responses indicate the degree of structural sensitivity depending on the character of incident. The dynamic coefficient KD was adopted as a parameter for the evaluation of structural sensitivity.

Rheology of alumina suspensions stabilized with Tiron

Gulicovski, J.J.,Cerovic, Lj.S.,Milonjic, S.K. The Korean Society of Rheology 2008 Korea-Australia rheology journal Vol.20 No.2

Pressure filtration technique was used to obtain defect-free microstructure of green cast ceramic bodies. Stable alumina suspensions of desired rheology (<5 Pa s at $1\;s^{-1}$) containing 60-80 mass. % solid loading were prepared in the alkaline region (at $pH{\approx}9$) with an optimum amount of 0.5 dmb % of Tiron added. Acidic region (at $pH{\approx}4$) enabled the preparation of 60 mass. % suspensions with addition of 1.5 dmb % of Tiron. The best quality slip was processed from an 80 mass.% suspension with 63% of theoretical density. The homogeneity of particle packing and the absence of defects in microstructure were proven by narrow pore size distribution (ranging from 32 to 64 nm, with up to 85% abundance), confirming advantages of the wet consolidation route.