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Wyświetlanie 1-13 z 13
Tytuł:
On some methods in safety evaluation in geotechnics
Autorzy:
Puła, W.
Zaskórski, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/178170.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
reliability index
random field
Eurocode 7
Opis:
The paper demonstrates how the reliability methods can be utilised in order to evaluate safety in geotechnics. Special attention is paid to the so-called reliability based design that can play a useful and complementary role to Eurocode 7. In the first part, a brief review of first- and second-order reliability methods is given. Next, two examples of reliability-based design are demonstrated. The first one is focussed on bearing capacity calculation and is dedicated to comparison with EC7 requirements. The second one analyses a rigid pile subjected to lateral load and is oriented towards working stress design method. In the second part, applications of random field to safety evaluations in geotechnics are addressed. After a short review of the theory a Random Finite Element algorithm to reliability based design of shallow strip foundation is given. Finally, two illustrative examples for cohesive and cohesionless soils are demonstrated.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 2; 17-32
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of time on the bearing capacity of precast piles
Autorzy:
Gwizdała, K.
Więcławski, P.
Powiązania:
https://bibliotekanauki.pl/articles/178842.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pale fundamentowe
pale prefabrykowane
nośność pali
nośność graniczna
Eurokod 7
bearing capacity
precast pile
Eurocode 7
Opis:
One of the most popular types of foundations in layered subsoil with very differentiated soil shear strengths are precast piles. One of the reasons is the fact that we can well control the driving process during the installation of these piles. The principles of the assessment of bearing capacity and settlements of the piles given by Eurocode 7, concentrate on two main methods, i.e., Static Pile Load Tests (SPLT) and Dynamic Driving Analysis (PDA). However, the evaluation of real load-settlement curve for piles being driven in layered subsoil, where non- cohesive and cohesive soils occur alternately, is neither easy nor straightforward. In the paper, the results of both SPLT and PDA tests for objects on the highways in Poland are presented. Field investigations carried out at various time points since the installation of piles (from 7 to 90 days) revealed an increase of bearing capacity with time. The reason for this may be a change of the soil state near the piles due to their driving (displacement of piles) as well as a change of microstructure at the contact between soil and pile shaft. The results of load tests were referred to the geotechnical parameters of the subsoil, which was recognized by means of traditional borings and CPTU tests. The results of tests allow phenomena occurring with time to be assessed and bearing capacity of precast piles to be predicted.
Źródło:
Studia Geotechnica et Mechanica; 2013, 35, 4; 65-74
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The comparative study of influence of lactic and glycolic acids copolymers type on properties of daunorubicin loaded nanoparticles and drug release
Autorzy:
Nikolskaya, E.
Sokol, M.
Faustova, M.
Zhunina, O.
Mollaev, M.
Yabbarov, N.
Tereshchenko, O.
Popov, R.
Severin, E.
Powiązania:
https://bibliotekanauki.pl/articles/307136.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
nanocząsteczki
daunorubicyna
PLGA
uwalnianie kontrolowane
stała dysocjacji
nanoparticles
daunorubicin
controlled release
MCF7/MCF7 Adr
dissociation constant
Opis:
The aim of this study was to compare the physico-chemical and biological properties of polymeric nanoparticles obtained from poly(DL-lactide-co-glycolide) (PLGA) with different ratios of monomers loaded with daunorubicin (DNR). Methods: DNR-loaded nanoparticles (NPs) were prepared with use of modified simultaneous double-emulsion solvent evaporation/diffusion technique. NPs were characterized using dynamic light scattering, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, and differential scanning calorimetry and Fourier transform infrared spectroscopy. Results: NPs with DNR were differing in size and zeta potential, depending on the type of polymer. The data obtained show that total content of DNR correlates with the values of the binding constant of DNR with polymers. The release of DNR from NPs proceeds predominantly for polymers with lower binding constants. The in vitro study of NPs on the MCF-7 cells showed similar activity of particles and substances while for the anthracycline-resistant MCF-7Adr cells the cytotoxicity of the nanoparticles was 3 to 7 times higher depending on the type of copolymer. Conclusions: PLGA DNR-loaded nanoparticles can be used to overcome multidrug resistance (MDR) as well as for reducing the frequency of DNR reception due to the prolonged effect, which allows maintaining the concentration of the drug at the required level. The usefulness of binding constant calculations for obtaining nanoparticles with the maximum drug loading was proven. The rate of drug administration and the frequency of administration can be calculated based on the DNR release profiles and release parameters that depend on polymer type.
Źródło:
Acta of Bioengineering and Biomechanics; 2018, 20, 1; 65-77
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimizing of the piezo-optic interaction geometry in SrB4O7 crystals
Autorzy:
Buryy, O.
Demyanyshyn, N.
Mytsyk, B.
Andrushchak, A.
Powiązania:
https://bibliotekanauki.pl/articles/174724.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
piezo-optical effect
optical path
path difference
SrB4O7 crystals
Opis:
The optimal geometries of the piezo-optic interaction are determined for SrB4O7 crystals by the extreme surfaces method. The goal functions of optimization are the change of optical path length and optical path difference, normalized on mechanical stress and crystal thickness, and the parameters of optimization are the spherical angles determining the directions of the light beam propagation and the uniaxial pressure action. It is shown that the maximal changes of optical path length for the orthogonal polarized waves are equal to 2.09 or 1.65 B (1 B = 1 brewster = 10–12 m2/N) and the maximal change of optical path difference is equal to 2.22 B respectively in transversal geometry of the piezo-optic interaction (for λ =633nm and T =20ºC).
Źródło:
Optica Applicata; 2016, 46, 3; 447-459
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of Ti-6Al-7Nb titanium alloy nitrocarburized under glow discharge conditions
Autorzy:
Kajzer, A.
Grzeszczuk, O.
Kajzer, W.
Nowińska, K.
Kaczmarek, M.
Tarnowski, M.
Wierzchoń, T.
Powiązania:
https://bibliotekanauki.pl/articles/306236.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Ti-6Al-7Nb alloy
diffusive nitrocarburized layer
mechanical properties
electrochemical properties
Opis:
The paper presents the results of physicochemical and mechanical properties of the Ti-6Al-7Nb alloy with surface modified by formation of a diffusive nitrocarburized layer deposited in a low-temperature plasma process. The main aim of the study was to evaluate the influence of steam sterilization and exposure to Ringer’s solution on the utility properties of the alloy. Methods: Based on the study of the microstructure, roughness, wettability, resistance to pitting corrosion, ion infiltration and mechanical properties, the usefulness of the proposed method of surface treatment for clinical application was proven. Results: Deposition of the nitrocarburized layer increased the surface roughness and surface hardness, but also reduced the contact angle, and corrosion resistance with respect to the polished surfaces. The nitrocarburized layer is a barrier against the infiltration of ions to the solution and sterilization and exposure to Ringer solution have greater effect on the physicochemical properties rather than on the mechanical ones. Conclusion: It was found that sterilization, and exposure to Ringer’s solution greatly affect the change of physicochemical properties rather than mechanical properties for both nitrocarburized layers and the Ti-6Al-7Nb alloy of mechanically polished surface.
Źródło:
Acta of Bioengineering and Biomechanics; 2017, 19, 4; 181-188
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of growing grains in microstructure of the 61SiCr7 spring steel
Autorzy:
Królicka, A.
Powiązania:
https://bibliotekanauki.pl/articles/1189961.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rozmiar ziarna
rozrost ziarna
mikrostruktura
stal 61SiCr7
bainit
stal krzemowa
parametry obróbki cieplnej
grain size
grain growth
microstructure
61SiCr7 steel
bainite
Si-rich steel
heat treatment parameters
Opis:
The article presents results from determination of a grain size in microstructure of the 61SiCr7 (60C2A) spring steel. The material was selected with respect to the possibility of obtaining a nano-structured bainite without carbide precipitates. This was conducted basing on an influence of grain size on bainitic transformation time, microstructure and mechanical properties of the material type considered. The experiments indicated, that the addition of silicon caused difficulties related to revealing the grain boundaries of the austenite. Optimal parameters of heat treatment, which enable to reach the microstructure for observing grain sizes of the steel are shown. The growing grains of the tested steel was followed at five values of austenitizing temperature.
Źródło:
Interdisciplinary Journal of Engineering Sciences; 2018, 6, 1; 44--47
2300-5874
Pojawia się w:
Interdisciplinary Journal of Engineering Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The ability of S.aureus to form biofilm on the Ti-6Al-7Nb scaffolds produced by Selective Laser Melting and subjected to the different types of surface modifications
Autorzy:
Szymczyk, P.
Junka, A.
Ziółkowski, G.
Smutnicka, D.
Bartoszewicz, M.
Chlebus, E.
Powiązania:
https://bibliotekanauki.pl/articles/306293.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
SLM
micro-CT
scaffolds
Ti-6Al-7Nb alloy
orthopedics
S.aureus
ortopedia
Opis:
The Gram-positive coccus, Staphylococcus aureus, is the leading etiologic agent of limb and life-threatening biofilm-related infections in the patients following the orthopaedic implantations. The aim of the present paper is to estimate the ability of S. aureus to form biofilm on titanium alloy (Ti-6Al-7Nb) scaffolds produced by Selective Laser Melting (SLM) and subjected to the different types of surface modifications, including ultrasonic cleaning and chemical polishing. The results obtained indicate significantly the decreased ability of S.aureus to form biofilm on the surface of scaffolds subjected to the chemical polishing in comparison to the scaffolds cleaned ultrasonically. The data provided can be useful for future applications of the SLM technology in production of Ti-6Al-7Nb medical implants.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 1; 69-76
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pile load capacity – calculation methods
Autorzy:
Wrana, B.
Powiązania:
https://bibliotekanauki.pl/articles/178838.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pile load capacity calculation
Eurocode 7
α – method
β – method
direct methods based on CPTu data
Opis:
The article is a review of the current problems of the foundation pile capacity calculations. The article considers the main principles of pile capacity calculations presented in Eurocode 7 and other methods with adequate explanations. Two main methods are presented: α – method used to calculate the short-term load capacity of piles in cohesive soils and β – method used to calculate the long- term load capacity of piles in both cohesive and cohesionless soils. Moreover, methods based on cone CPTu result are presented as well as the pile capacity problem based on static tests.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 4; 83-93
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm
Autorzy:
Junka, A. F.
Szymczyk, P.
Secewicz, A.
Pawlak, A.
Smutnicka, D.
Ziółkowski, G.
Bartoszewicz, M.
Chlebus, E.
Powiązania:
https://bibliotekanauki.pl/articles/307092.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
technologia SLM
Pseudomonas aeruginosa
skafoldy
modyfikacja powierzchni
Ti-6Al-7Nb
SLM technology
scaffolds
surface modification
Opis:
In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann–Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann–Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 1; 115-120
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The mechanism of $CaCO_3$ in the gas-based direct reduction of a high-phosphorus oolitic iron ore
Autorzy:
Wu, Shichao
Li, Zhengyao
Sun, Tichang
Kou, Jue
Xu, Chengyan
Powiązania:
https://bibliotekanauki.pl/articles/1446124.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
high-phosphorus oolitic iron ore
gas-based direct reduction
magnetic separation
$Fe_3PO_7$
$CaCO_3$
Opis:
Gas-based direct reduction and magnetic separation process was applied in treating a high-phosphorus oolitic iron ore, of which phosphorus mainly occured as $Fe_3PO_7$ and apatite. The mechanism of $CaCO_3$ was investigated using XRD, SEM-EDS, and mineral phase analysis. Results showed that when no CaCO3 was added, most of the iron minerals were reduced to metallic iron, while $Fe_3PO_7$ was reduced to elemental phosphorus and mixed with the metallic iron particles. When a small amount of $CaCO_3$ was added, $CaCO_3$ preferentially reacted with $SiO_2$, $Al_2O_3$ and other components, preventing them from reacting with FeO and resulting in the increase of iron recovery. When the amount of $CaCO_3$ reached 25%, apatite was produced from the reaction of CaO and $Fe_3PO_7$, which could be later removed by grinding and magnetic separation.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 4; 117-124
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical methods applied in thickness and topography testing of passive layers on implantable titanium alloys
Autorzy:
Szewczenko, J
Jaglarz, J
Basiaga, M
Kurzyk, J
Paszenda, Z
Powiązania:
https://bibliotekanauki.pl/articles/173875.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomaterials
Ti-6Al-7Nb
passive layer
light scattering
bidirectional reflection distribution function (BRDF)
thin films optics
Opis:
The work presents the results of the applied surface pretreatment on topography and thickness of a passive layer of the anodically oxidized Ti6Al7Nb alloy. In our study were used: integrating sphere spectral measurements, bidirectional reflection distribution function (BRDF) method and optical profilometry. On the basis of the study, the passive layer thickness, roughness, waviness and the autocorrelation length were determined. The influence of voltage of anodization on topographical parameters of TiO2 has been discussed.
Źródło:
Optica Applicata; 2013, 43, 1; 173-180
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of post-process operations on the mechanical properties of titanium alloy Ti-6Al-7Nb, produced by selective laser melting
Autorzy:
Karoluk, M.
Chlebus, E.
Powiązania:
https://bibliotekanauki.pl/articles/1190025.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
selektywne spiekanie laserowe
SLM
stop tytanu
Ti-6Al-7Nb
selective laser melting
post-process operations
titanium alloy
Opis:
Even though selective laser melting (SLM) has been available for more than a decade, during few last years the interest in this technology has grown extremely. SLM technology allows to fabricate fully functional and complex metal objects, layer by layer, via selective melting of material using laser beam. However, producing object by melting thin layers of material causes conditions of fast heat removal. This phenomenon leads to equilibrium microstructures, accompanied by the residual stresses which cause the decrease of mechanical properties. The following paper presents the result of research in the field of the influence of the post-process operations, such as machining and heat treatment, on the mechanical properties of alloy Ti-6Al-7Nb build by SLM.
Źródło:
Interdisciplinary Journal of Engineering Sciences; 2015, 3, 1; 16--19
2300-5874
Pojawia się w:
Interdisciplinary Journal of Engineering Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biodegradable polymer coatings on Ti6Al7Nb alloy
Autorzy:
Szewczenko, Janusz
Kajzer, Wojciech
Kajzer, Anita
Basiaga, Marcin
Kaczmarek, Marcin
Antonowicz, Magdalena
Nowińska, Katarzyna
Jaworska, Joanna
Jelonek, Katarzyna
Kasperczyk, Janusz
Powiązania:
https://bibliotekanauki.pl/articles/306476.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Ti6Al7Nb
powłoka polimerowa
zwilżalność
odporność na korozję
uwalnianie jonów
przyczepność
biodegradable polymer coating
wettability
corrosion resistance
ion release
adhesion of polymer coatings
Opis:
The aim of the study was to determine the influence of long term exposure to Ringer’s solution of biodegradable polymer coatings containing an active substance on the Ti6Al7Nb alloy substrate on the physical and chemical properties of the coatings and the degradation process of the metal substrate. The studies used poly(L-lactide-co-trimethylene carbonate) P(L/TMC), poly(L-lactide-co-trimethylene carbonate-glycolide) P(L/TMC/G) and poly(D,L-lactide-glycolide) (PLGA) coatings applied to the anodically oxidized Ti6Al7Nb alloy by means of dipping method (1, 2 and 3 dips). The polymer coatings contained ciprofloxacin. Roughness and wettability tests were carried out on the substrate and polymer coatings, the pitting corrosion resistance of the substrate and samples with polymer coating was determined, the number of metallic ions released to the solution from the coated and uncoated samples was determined as well as the adhesion of polymer coatings. The research was supplemented by microscopic observations. The results of the research indicate different influence of exposure to Ringer’s solution on the physical and chemical properties of biodegradable polymer coatings containing ciprofloxacin and the course of the degradation process of the metal substrate.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 4; 83-92
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-13 z 13

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