Early serum biomarkers of ischemic stroke

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Numerical Modelling of Y Joints of Trusses Made of Steel Hollow Sections

The use of welded structural hollow sections in civil engineering is relatively new. Constructing and dimensioning joints of steel trusses made of welded structural hollow sections requires a more specified approach, compared to traditional joints, achieved by gusset plates. Stress and local deformations at the contact between elements are non-linear and very complex. In this paper, the FEM modelling of the Y-joint was performed, accounting for the non-linear behaviour of steel. The ultimate bearing capacities of the joint were determined numerically, by applying different failure criteria. The results showed very good agreement with the experimental data

Global Analysis of Steel Constructions with Semi-Rigid Connections

In this paper, original extension of classic deformation method for global elastic analysis of steel construction with semi-rigid connections is developed. The original calculation for steel frame structures with semi-rigid connections as a function of rotational rigidity of connection, a realistic parameter for determination of both tension and deformation fields of connection as well as entire construction, has been derived in detail. Due to its generality, simplicity and straight-forward calculation, the method developed in this paper is convenient for both computational utilization and hand calculations. For introduced rotational rigidity of realistic connections, the expressions for determination of bending moments at ends of semi-rigidly connected elements have been derived as well as conditional equations for determination of deformation-unspecified values at static load by first-order theory. The obtained results are illustrated in detail on a numerical example. Their comparison with the results of FEM analysis was provided

COMPARATIVE ANALYSIS OF USING DEGREE OF RIGIDITY AND ROTATIONAL STIFFNESS OF CONNECTIONS IN STRUCTURAL DESIGN

Using classical formulation of stiffness method, impact of semi-rigid connections on the stresses and strains can be analyzed by the degree of rigidity or by rotational stiffness of connections. In this paper, functional dependence between the degree of rigidity and rotational stiffness of connections is formulated and the comparative analysis of these two approaches in the analysis of semi-rigid connections behavior of members in real structures, is implemented

Klinička ispitivanja restauracija cervikalnih nekarijesnih lezija

The therapy of non-caries cervical lesions is an important problem in restorative dentistry, for the ambiguous aetiology, clinical diagnoses and for the selection of restorative procedure. Aim: The aim of this work was to clinically check the efficiency of non-caries cervical lesions restoration depending on materials used for restorative fillings. Materials and methods: Clinical researches covered 62 teeth of different morphology group at the patients of both gender and of different age. The restoration of gingival lesions, with no previous preparation, was done with composite adhesive system SINGLE BOND/Valux Plus (3M) (30 teeth) and with campomer DYRACT AO (Dentsplay) (32 teeth). The fillings were estimated on the checkups which took place on 3,6 and12 months applying modified criteria according to Ridge and Cvar. Results: The acquired results showed that after 3 to 6 months there were no changes at none of examined parameters and all the fillings got maximal mark A. 12 months latter, in the two cases with composite filling, the marginal adaptation got the mark B (607%). The marginal adaptation at two teeth restored with compomers got the mark B (6.3%) Postoperative sensitiveness phenomenon, marginal discoloration and secondary caries weren’t registered in none of the cases after the observation period of 12 months. Conclusion: For the restoration of non-caries cervical lesions, composite materials with suitable adhesive system and the new generation of compomers could be used.Terapija nekarijesnih cervikalnih lezija je značajan problem u restaurativnoj stomatologiji, zbog nejasne etiologije, kliničke dijagnoze ali i izbora restaurativne procedure. Cilj: Cilj ovog rada je bio da se klinički proveri efikasnost restauracija nekarijesnih cervikalnih lezija zuba u zavisnosti od korišćenih materijala za restaurativne ispune. Materijal i metod: Klinička ispitivanja su obuhvatila 62 zuba različitih morfoloških grupa kod pacijenata oba pola i različite starosti. Restauracija gingivalnih lezija, bez prethodne preparacije, urađena je kompozitnim adhezivnim sistemom SINGLE BOND/Valux Plus (3M) (30 zuba) i kompomerom DYRACT AP (Dentsplay) (32 zuba). Ispuni su procenjivani na kontrolnim pregledima posle 3, 6 i 12 meseci primenom modifikovanih kriterijuma po Ridge-u i Cvar-u. Rezultati: Dobijeni rezultati su pokazali da posle 3 i 6 meseci nije bilo promena na ispunima ni kod jednog ispitivanog parametra i svi ispuni su ocenjeni maksimalnom ocenom A. Posle 12 meseci, u dva slučaja ispunjenih kompozitima, ivična adaptacija je ocenjena ocenom B (6,7%). Ivična adaptacija je i u dva zuba restaurisanih kompomerima ocenjena ocenom B (6,3%). Pojava postoperativne osetljivosti, ivične diskoloracije i sekundarnog karijesa nije registovana ni u jednom slučaju posle observacionog perioda od 12 meseci. Zaključak: Za restauraciju nekarijesnih cervikalnih lezija mogu se koristiti kompozitni materijali sa odgovarajućim adhezivnim sistemima i novije generacije kompomera

Mogućnost prevencije postoperativne osetljivosti u zuba restaurisanih kompozitnim ispunima

Introduction: Postoperative sensitivity is a common problem in patients after placement of resin-based composite (RBC) restorations. Aim: The of this study was to evaluate clinical efficacy of oxalate desensitizer BisBlock in the prevention of postoperative sensitivity after placement of RBC restorations. Materials and Methods: This clinical study was conducted at Belgrade University School of Dentistry Department of Restorative Dentistry and Endodontics. The study comprised 31 patients, both sexes, aged 18 - 32. In each patient, two class II cavities were prepared in premolars (62 cavities) and restored with RBCs. One restored tooth in each patient was treated with BisBlock (experimental group) while another served as control. In the restorative procedure, Single Bond (3M ESPE) was used as the adhesive and teeth were restored with Valux Plus (3M ESPE) RBC. Sensitivity evaluation was performed at day 1, day 4 and day 7 after restoration and comprised sensitivity on thermal and osmotic stimuli as well as sensitivity during mastication. Results: The obtained results revealed statistically significant decrease of postoperative sensitivity in experimental (3.23%) than control group (16.14%). .Uvod: Postoperativna osetljivost je čest problem kod pacijenata nakon postavljanja kompozitnih ispuna na zubima. Cilj ovog istraživanja je bio da se proveri klinička efikasnost oksalatnog desenzibilizatora BisBlock u prevenciji postoperativne osetljivosti posle postavljanja kompozitnih ispuna na bočnim zubima. Materijal i metod: Kliničko istraživanje je sprovedeno na Klinici za Bolesti zuba Stomatološkog fakulteta Univerziteta u Beogradu. U istraživanje je uključen 31 pacijent, osoba oba pola, uzrasta od 18 do 32 godine. Kod svakog pacijenta su urađena dva kaviteta druge klase na premolarima (62 kaviteta) i restaurisani kompozitnim ispunima. Jedan restaurisani zub svakog ispitanika je tretiran BiSBlock-m (ekperimentalana grupa) dok je drugi poslužio kao kontrolna grupa. U restaurativnoj proceduri kao adhezivno sredstvo je korišćen Single Bond (3M ESPE) a zubi su restaurisani kompozitnim materijalom Valux plus(3M ESPE). Procena osetljivosti je vršena posle prvog, četvrtog i sedmog dana od restauracije, ispitivanjem osetljivosti na termičke i osmotske nadražaje i ispitivanjem osetljivosti na pritisak u toku mastikacije. Rezultati: Dobijeni rezultati su pokazali da je upotrebom desenzibilizatora BisBlock-a došlo do statisticki značajnog smanjenja pojave postoperativne osetljivosti kod eksperimentalne (3.23%.) u odnosu na kontrolnu grupu (16.14%).

Cyber-Physical Manufacturing Metrology Model (CPM3) for Sculptured Surfaces - Turbine Blade Application

Cyber-Physical Manufacturing (CPM) and digital manufacturing represent the key elements for implementation of Industry 4.0 framework. Worldwide, Industry 4.0 becomes national research strategy in the field of engineering for the following ten years. The International Conference USA-EU-Far East-Serbia Manufacturing Summit was held from 31st May to 2nd June 2016 in Belgrade, Serbia. The result of the conference was the development of Industry 4.0 Model for Serbia as a framework for New Industrial Policy - Horizon 2020/2030. Implementation of CPM in manufacturing systems generates " smart factory". Products, resources, and processes within smart factory are realized and controlled through CPM model. This leads to significant advantages with respect to high product/process quality, real-time applications, savings in resources consumption, as well as, lower costs in comparison with classical manufacturing systems. Smart factory is designed in accordance with sustainable and service-oriented best business practices/models. It is based on optimization, flexibility, self-adaptability and learning, fault tolerance, and risk management. Complete manufacturing digitalization and digital factory are the key elements of Industry 4.0 Program. In collaborative research, which we carry out in the field of quality control and manufacturing metrology at University of Belgrade, Faculty of Mechanical Engineering in Serbia and at Department of Mechanical Engineering, University of Texas, Austin in USA, three research areas are defined: (a) Digital manufacturing - towards Cloud Manufacturing Systems (as a basis for CPS), in which quality and metrology represent integral parts of process optimization based on Taguchi model, and (sic) Cyber-Physical Quality Model (CPQM) - our approach, in which we have developed and tested intelligent model for prismatic parts inspection planning on CMM (Coordinate Measuring Machine). The third research area directs our efforts to the development of framework for Cyber-Physical Manufacturing Metrology Model (CPM3). CPM3 framework will be based on integration of digital product metrology information through metrology features recognition, and generation of global/local inspection plan for free-form surfaces; we will illustrate our approach using turbine blade example. This paper will present recent results of our research on CPM3

Examination of scanner precision by analysing orthodontic parameters

Background: 3D modelling in orthodontics is becoming an increasingly widespread technique in practice. One of the significant questions already being asked is related to determining the precision of the scanner used for generating surfaces on a 3D model of the jaw. Materials and methods: This research was conducted by generating a set of identical 3D models on Atos optical 3D scanner and Lazak Scan laboratory scanner, which precision was established by measuring a set of orthodontic parameters (54 overall) in all three orthodontic planes. In this manner we explored their precision in space, since they are used for generating spatial models - 3D jaws. Results: There were significant differences between parameters scanned with Atos and Lazak Scan. The smallest difference was 0.017 mm, and the biggest 1.109 mm. Conclusion: This research reveals that both scanners (Atos and Lazak Scan), which belong to general purpose scanners, based on precision parameters can be used in orthodontics. Early analyses indicate that the reference scanner in terms of precision is Atos

Friction stir welding of aluminium alloys - T joints

The paper presents results of research on the possibility of producing T-joints of aluminium alloys without defect by friction stir welding process. Friction stir welding process is applied in welding T-joints of aluminium alloys 5052-H32 and 5754-H111. These relatively new welding tech-nologies produce high quality welded joints, where strength of the joint can reach the strength of the base material. Visual and macrostructural examination and microhard-ness measuring of the welded T-joints are processed

Friction stir welding of aluminium alloys - T joints

The paper presents results of research on the possibility of producing T-joints of aluminium alloys without defect by friction stir welding process. Friction stir welding process is applied in welding T-joints of aluminium alloys 5052-H32 and 5754-H111. These relatively new welding tech-nologies produce high quality welded joints, where strength of the joint can reach the strength of the base material. Visual and macrostructural examination and microhard-ness measuring of the welded T-joints are processed