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J. Jaroszewicz

Abstract

A free vibration analysis of homogeneous and isotropic circular thin plates with nonlinear thickness variation and clamped edges is considered. The limited independent solutions of differential Euler equation were expanded in the power series based on the properties of integral equations. The analytical frequency equations as power series were obtained using the method of successive approximations.

Open access

K. Szlązak, J. Jaroszewicz, B. Ostrowska, T. Jaroszewicz, M. Nabiałek, M. Szota and W. Swieszkowski

Abstract

An optimal method for composites preparation as an input to rapid prototyping fabrication of scaffolds with potential application in osteochondral tissue engineering is still needed. Scaffolds in tissue engineering applications play a role of constructs providing appropriate mechanical support with defined porosity to assist regeneration of tissue. The aim of the presented study was to analyze the influence of composite fabrication methods on scaffolds mechanical properties. The evaluation was performed on polycaprolactone (PCL) with 5 wt% beta-tricalcium phosphate (TCP) scaffolds fabricated using fused deposition modeling (FDM). Three different methods of PCL-TCP composite preparation: solution casting, particles milling, extrusion and injection were used to provide material for scaffold fabrication. The obtained scaffolds were investigated by means of scanning electron microscope, x-ray micro computed tomography, thermal gravimetric analysis and static material testing machine. All of the scaffolds had the same geometry (cylinder, 4×6 mm) and fiber orientation (0/60/120°). There were some differences in the TCP distribution and formation of the ceramic agglomerates in the scaffolds. They depended on fabrication method. The use of composites prepared by solution casting method resulted in scaffolds with the best combination of compressive strength (5.7±0.2 MPa) and porosity (48.5±2.7 %), both within the range of trabecular bone.

Open access

Wioleta Radziszewska and Joanna Jaroszewicz

Abstract

Over the last several years, Poland has experienced dynamic development of linear infrastructure, mainly regarding national roads. The changes are reflected in the condition of the market of land located in the vicinity of newly constructed roads. The location of a property in the vicinity of an express road junction offers more convenient access to the labour market or sales market. On the other hand, possible negative effects include increased noise and pollution, as well as spatial continuum disturbance.

The objective of the study is the analysis of the effect of national roads on the development and dynamics of changes in prices of land in their vicinity. The estimation of the dynamics of such changes permits the determination of the stage of implementation of investments involving the highest variations of property prices. The analysis was conducted based on the following criteria: class of national roads (motorway or main express road) and the size of the urban centre located on route. The study involved the application of the Geographic Information Systems technology ArcGIS ESRI, data from the register of property prices and values, and cadastre information included on websites iGeoMap and Geoportal.

Open access

Janusz Jaroszewicz, Zuzanna Marcinkowska and Krzysztof Pytel

Abstract

The main objective of 235U irradiation is to obtain the 99mTc isotope, which is widely used in the domain of medical diagnostics. The decisive factor determining its availability, despite its short lifetime, is a reaction of radioactive decay of 99Mo into 99mTc. One of the possible sources of molybdenum can be achieved in course of the 235U fission reaction. The paper presents activities and the calculation results obtained upon the feasibility study on irradiation of 235U targets for production of 99Mo in the MARIA research reactor. Neutronic calculations and analyses were performed to estimate the fission products activity for uranium plates irradiated in the reactor. Results of dummy targets irradiation as well as irradiation uranium plates have been presented. The new technology obtaining 99Mo is based on irradiation of high-enriched uranium plates in standard reactor fuel channel and calculation of the current fission power generation. Measurements of temperatures and the coolant flow in the molybdenum installation carried out in reactor SAREMA system give online information about the current fission power generated in uranium targets. The corrective factors were taken into account as the heat generation from gamma radiation from neighbouring fuel elements as well as heat exchange between channels and the reactor pool. The factors were determined by calibration measurements conducted with aluminium mock-up of uranium plates. Calculations of fuel channel by means of REBUS code with fine mesh structure and libraries calculated by means of WIMS-ANL code were performed.

Open access

K. Mroczek, K. Szlązak, E. Jodkowska, J. Jaroszewicz, W. Swięszkowski and K.J. Kurzydłowski

Abstract

A progressive bacteria invasion on tooth tissues leads to pulp inflammation, microabscesses of the pulp, destruction and in consequence inflammation of periapical tissues. Therefore the aim of endodontic treatment is three dimensional debridement of a root canal from the vent in pulp chamber to the physiological narrowing. Therefore the aim of the study is analysis of root canal configuration, number of canals, presence of lateral canals and canal delta with the group of first permanent molars. At the same time the accuracy of the radiological examination (x-ray images) is estimated due to comprehension of X-ray images performed before teeth preparation with root canal system and after observation of transversal cuts by means of light microscopy and microtomography. This establishment is presented through the differences in conventional radiological image and clinical assessment.

Open access

B. Ostrowska, J. Jaroszewicz, E. Zaczynska, W. Tomaszewski, W. Swieszkowski and K.J. Kurzydlowsk

Abstract

Fabrication of scaffolds for tissue engineering (TE) applications becomes a very important research topic in present days. The aim of the study was to create and evaluate a hybrid polymeric 3D scaffold consisted of nano and microfibers, which could be used for bone tissue engineering. Hybrid structures were fabricated using rapid prototyping (RP) and electrospinning (ES) methods. Electrospun nanofibrous mats were incorporated between the microfibrous layers produced by RP technology. The nanofibers were made of poly(L-lactid) and polycaprolactone was used to fabricate microfibers. The micro- and nanostructures of the hybrid scaffolds were examined using scanning electron microscopy (SEM). X-ray microtomographical (μCT) analysis and the mechanical testing of the porous hybrid structures were performed using SkyScan 1172 machine, equipped with a material testing stage. The scanning electron microscopy and micro-tomography analyses showed that obtained scaffolds are hybrid nanofibers/microfibers structures with high porosity and interconnected pores ranging from 10 to 500um. Although, connection between microfibrous layers and electrospun mats remained consistent under compression tests, addition of the nanofibrous mats affected the mechanical properties of the scaffold, particularly its elastic modulus. The results of the biocompatibility tests didn’t show any cytotoxic effects and no fibroblast after contact with the scaffold showed any damage of the cell body, the cells had proper morphologies and showed good proliferation. Summarizing, using RP technology and electrospinning method it is possible to fabricate biocompatible scaffolds with controllable geometrical parameters and good mechanical properties.

Open access

K.K. Żur, J. Jaroszewicz and Ł. Dragun

Abstract

In the paper the influence function and the method of partial discretization in free axisymmetric vibration analysis of multilayered circular plates of constant and linearly variable thickness were presented. The effects of shear deformation and rotary inertia for the core as well as the facings were neglected. An analytical investigation based on the classical plate theory was made for the multilayered plate which satisfies Sokołowski’s condition. Discretization of mass and replacing stiffness of a fixed circular plate were presented. Formulas of influence matrix and Bernstein-Kieropian’s estimators for different steps of discretization were defined. The influence of variable distribution of parameters on the value of double estimators of natural basic and higher frequency of a sandwich circular plate was investigated.