Wyniki wyszukiwania - Biblioteka Nauki

1

The degradation of metal implants

100%

Świeczko-Żurek B. , Krzemiński M.

Advances in Materials Science

|

2008

|

tom Vol. 8, nr 1(15)

179-183

EN

The presence of metal implants in the human body causes some dangers, which result from introducing another object into organism. There may occur a biocorrosion, which causes different modifications of implant surface.

2

Degradation of a TiAl-base alloy in hot salt environments

80%

Godlewska E. , Jajko B. , Mitoraj M.

Advances in Materials Science

|

2007

|

tom Vol. 7, nr 2(12)

108-114

EN

The investigated material was a two-phase (gamma+alfa2) titanium aluminide alloy (Ti-46Al-8Nb) with a fully lamellar structure. The specimens were contaminated either with Na2SO4 or NaCl or a mixture of the two salts, and subjected to thermal cycling in air at 700°C, 800°C or 900°C. The progress of degradation was followed by recording mass variations after consecutive 20-hour cycles. The overall duration of each test was 300 hours. The post-test examination included morphology, chemical and phase composition of the corrosion products, extent and type of alloy degradation. After the test, Ti and Al concentrations in the near-surface layer of the alloy were lower than in the bulk. The depletion zone was the widest in the case of specimens contaminated with sodium chloride. Numerous macrodefects were visible in this region. The Ti-46Al-8Nb alloy demonstrated poor resistance to hot corrosion.

3

Research on possibilities of application of nondestructive testing in degradation evaluation of materials used in infrastructure working under the influence of agressive hydrogen environment

80%

Paradowski K. , Manaj W. , Spychalski L. , Zagórski K. , Lubińska D. , Kukla D. , Płowiec J. , Kurzydłowski K. J.

Advances in Materials Science

|

2007

|

tom Vol. 7, nr 2(12)

276-283

EN

Widely applied materials, used in construction of installations exposed to influence of hydrogen environment, are low-alloy Cr-Mo steels. Unfavorable effect of hydrogen on metals is described as hydrogen stress corrosion or hydrogen embrittlement. The process, in extreme cases, leads to a significant decrease of utilitarian properties of construction materials. In true conditions, a consequence of hydrogen degradation may be a failure, brought about by a los s of construction's integrity. Usage of modem inspection techniques constituting non-destructive testing methods enables monitoring and evaluation of degradation degree of materials, out of which the equipment was built, in a way that does not effect a change of their properties and utili-tarian functions. The presented in the paper research results, obtained under laboratory conditions, are a base for creation of a non-destructive tests methodology that enables performing inspections in true conditions and allows for a better interpretation of results obtained.

4

Environmental degradation of titanium biomaterials: mechanisms, effects, testing and evaluation

80%

Zieliński A. , Sobieszczyk S.

Advances in Materials Science

|

2007

|

tom Vol. 7, nr 2(12)

189-201

EN

The possible causes and mechanisms of degradation of titanium biomaterials used as long term implants for some joints are discussed. The effects of presence of metallic implant in human body are reviewed. The current testing procedures and their imperfections are shown. The evaluation procedure of biomaterials is proposed.

5

Ageing phenomena in structural adhesion

80%

Shanahan M. E. R.

Advances in Materials Science

|

2007

|

tom Vol. 7, nr 2(12)

159-166

EN

Structural adhesion is becoming more and more prevalent in various industrial applications, notably in transport. Apart from the many advantages of adhesive bonding (weight-saving, stress reduction, possibility to join dissimilar materials, etc…), it must nevertheless be noted that certain disadvantages exist, inc1uding ageing in deleterious liquid environments, particularly water. This note gives a brief overview of aspects of ageing, with particular attention to kinetic features.

6

Degradation of composites based on raw materials for orthopedic equipment

80%

Szaraniec B. , Morawska-Chochół A. , Stodolak-Zych E.

Engineering of Biomaterials

|

2012

|

tom Vol. 15, no. 116-117 spec. iss.

147

EN

Eco-composites based on natural raw materials such as polylactide and plant fibres (e.g. flax, hemp, jute) show many important features which enable them to be used as potential materials for biomedical engineering. Availability of the raw materials and low costs of production, capability to enhance mechanical parameters and also controlled time of degradation in the environment allow considering them as materials for rehabilitation equipment, orthopedic supplies or materials for medical packages. Such materials due to the presence of the natural fibres provide higher comfort during their utilization and then they undergo safe biodegradation which is non-harmful for the environment [1,2]. The work presents attempts on fabrication of composites based on polylactide (PLA, Ingeo 3051D, Nature works, USA) reinforced with short flax and jute fibres. The fibres were mechanically comminuted to the length of 1-2 mm. Preparation of PLA/fibres mixture took part in two stages. The first one consisted in drying of the polymer granulate and the fibrous filler at 60 degrees of Celsius for 2 h. The second stage the granulate/fibres mixture was homogenized using vertical screw injection moulding machine (Multiplas). The obtained mixture was mechanically comminuted with a laboratory grinder (Testchem). Volume fraction of the fibres was nit higher then 5 %. The granulates were used to prepare PLA/natural fibres composites in the form of paddle-shaped samples (according to PN-EN ISO 527) by the injection method. The injection took place at 165 degrees of Celsius and pressure of 80 kg/cm2. The samples were subjected to hydrolytic degradation tests (incubation in distilled water at 37 degrees of Celsius, 15 weeks) and biological degradation (composting in an eco-composter, TERMO-410 with the addition of Radvit activator which contains composting bacteria and selected fungi cultures which support biodegradation and accelerate degradation of organic wastes, 15 weeks). The effect of the degradation environment on the composite material was determined on the basis of changes of its mechanical properties (tensile strength, Young's modulus) using an universal testing machine (Zwick 1453). The degradation process was monitored by FT-IR spectroscopy of the composite samples (transmission method, BioRAD 60FT). Changes related to the polymer chain degradation were assessed on the basis of viscosimetric measurements (Hoppler method). The carried out investigations proved, that during both the composting and the incubation in water a gradual degradation of the material takes place. Its visual effect was decrease of the tensile strength of the composites for about 70% for PLA/5% jute and for c.a. 10% for PLA/5% hemp and their Young's modulus for about 25 % for PLA/5% jute and for c.a. 10% for PLA/5% hemp. The changes were caused by decrease of molecular weight (Mn) of the polymer matrix from 100 to 28 kDa for PLA/5% hemp, and from 136 to 48 kDa for PLA/5% jute. The change of the polymer structure was faster in the case of degradation in water environment. This effect was related to facilitated migration of medium (water) inside the material and possibility of washing out and transport of products of the polymer chain disintegration. Additionally, the present fibrous phase which is characterized by high water absorbability may became a reservoir of both the medium and the degradation products. Biodegradation in the compost heap was slower and it was an example of synergic effect of hydrolytic degradation and biodegradation caused by the microorganisms. This process could be observed on the FT-IR spectra recorded during degradation in the compost heap, where longer composting time led to increasing disproportion between bands indicating increasing fraction of hydroxyl, carboxyl and carbonyl groups in relation to groups characteristic for PLA chain. In the case of biodegradation the process progress is related to such variable factors as: amount and type of the bacteria and fungi cultures, humidity and temperature. In conclusion, it may be stated that the proposed PLA/natural fibres composite materials are an alternative solution for many fields of biomedical engineering especially for rehabilitation and orthopedic provision.

7

Degradacja gleb na terenach rolniczych

80%

Boroń K.

Przegląd Geodezyjny

|

2007

|

tom R. 79, nr 8

12-14

PL

Praca przedstawia definicje degradacji gleb, podawane przez różnych autorów. W pracy przeanalizowano przyczyny i formy degradacji gleb terenów rolniczych. Opracowanie wyjaśnia rolę czynników przyrodniczych i antropogenicznych, wpływających na procesy degradacji gleb. Podkreślono także rolę niewłaściwej praktyki rolniczej w procesie degradacji gleb.

EN

The paper presents set of soil degradation definitions according to some authors. The reasons and the forms of soil degradation of agricultural lands were under analysis. The paper was focusing on a natural and anthropogenic factors, influencing soil degradation processes. The role of inappropriately agricultural practice in soil degradation was emphasized.

8

Degradation of the polymer prosthetic material in model body fluids

80%

Heimowska A. , Brzeska J. , Morawska M. , Gorska M.

Towaroznawcze Problemy Jakości. Polskie Towarzystwo Towaroznawcze

|

2017

|

nr 2

9

Effect of electrospinning conditions on PLA fibers morphology and UV degradation

80%

Kosowska K. , Procner M. , Szatkowski P.

Engineering of Biomaterials

|

2017

|

tom Vol. 20, no. 143 spec. iss.

60

10

Preparation and Photocatalytic Properties of a Kind of Loaded Photocatalyst of Nanoscale CuO/ZnO Composite

80%

Zhang D. F.

Polish Journal of Chemistry

|

2009

|

tom Vol. 83, nr 11

2009-2019

EN

The nanoscale CuO/ZnO composite photocatalysts were prepared via the wet chemical route. The detailed structural and physico-chemical properties of the obtained products were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy, FT-IR spectroscopy and fluorescence spectra. The vis i ble-light photocatalytic activity of CuO/ZnO nanocomposite was evaluated by employing the photodegradation of dye molecules (methyl orange, MO) as a probe reaction in aqueous solution. The effects of various parameters such as catalyst dosage and pH value of suspension on photocatalytic degradation efficiency of MO were investigated. The results indicate that the photocatalytic activity of CuO/ZnO nanocomposite is much better than that of commercial TiO2 photocatalyst and the photocatalytic ability of nanocomposite is almost not decreased after a four-cycle degradation of MO.

11

Degradability of organic-inorganic cellulose acetate butyrate hybrids in sea water

80%

Wojciechowska P. , Heimowska A. , Foltynowicz Z. , Rutkowska M.

Polish Journal of Chemical Technology

|

2011

|

tom 13

|

nr 2

29-34

EN

Environmental degradability of novel organic-inorganic cellulose acetate butyrate hybrids obtained via solgel process was investigated. The degradation of hybrids was studied under marine exposure conditions in the Baltic Sea for a period of 25 weeks. The influence of characteristic parameters of sea water on the degree of degradation monitored by changes of weight and optical microscopy was discussed. The degraded samples were also examined by FT-IR spectroscopy. It has been established that the CAB/silica hybrids are more susceptible to biodegradation in sea water environment than pure cellulose acetate butyrate.

12

Biodegradable plastics

80%

Kozłowski M. , Kozłowska A.

Prace Naukowe Instytutu Inżynierii Ochrony Środowiska Politechniki Wrocławskiej. Konferencje

|

2006

|

tom Vol. 81, nr 12

25-30

PL

Omówiono aktualny stan w zakresie produkcji, zastosowań oraz perspektyw rozwojowych tworzyw polimerowych ulegających degradacji w środowisku naturalnym. Omówiono rodzaje tych tworzyw, technologie otrzymywania i właściwości w porównaniu do wielko tonażowych tworzyw sztucznych. Przedstawiono wybrane wyniki własnych badań oraz inicjatywy badawcze Unii Europejskiej na przykładzie projektu BIOCOMP.

EN

Consumption of polymeric materials have increased worldwide for approximately 5 fold within recent 30 years (up to ca. 240 Mt) and this trend is expected to continue during following years. There should be 2 to 3 fold increase in plastics consumption, mainly due to increasing demand for plastics in developing countries. In parallel the amount of plastic waste will grow, demanding sound waste management in order to protect environment, health and living standards. Current practice for plastic waste management includes recovery and landfilling. Considering that sustainable development is the only viable social and economic model, one should reduce landfilling as much as possible. The European Union is planning to stop that practice in the year 2030.

13

Fabrication and physicochemical properties of pectin/chitosan scaffolds

80%

Kulikouskaya V. , Lazouskaya M. , Agabekov V.

Engineering of Biomaterials

|

2018

|

tom Vol. 21, no. 146

2--7

EN

Scaffolds from chitosan and its combinations with other polymers are widely used for tissue engineering application. This is due to the favourable biological properties of chitosan such as antimicrobial activity, biocompatibility, biodegradability, cell adhesion and proliferation, etc. The aim of the study was the creation of 3D porous scaffolds based on pectin/chitosan polyelectrolyte complexes and study the influence of components ratio on their physico-chemical properties, as well as degradation behaviour in solutions modelling the media of the human body. Porous “sponge-like” polysaccharide films were produced using freeze-drying technique from gel-like pectin-chitosan polyelectrolyte complexes. The weight ratio of chitosan:pectin in complexes was varied in the range from 1:1 to 1:2. Obtained samples were characterized by infrared spectroscopy and scanning electron microscopy. It has been shown that pectin-chitosan films turned out to have sponge-like structure with highly interconnected pores with the size about 50-300 μm. It has been determined that all samples regardless of the chitosan:pectin ratio possess high swelling properties. The degradation profile of scaffolds in different media was studied. It has been determined that the largest weight loss is observed in water and reaches more than 80% after 1 day, while in NaCl and PBS solutions weight loss is approximately 50-60% after 25 days. For samples with different chitosan:pectin weight ratio, weight loss slightly rise with increasing amount of pectin. It has been shown that mesenchymal stem cells adhered to the surface of obtained pectin:chitosan porous scaffolds in viable state. Hence, it can be served as a potential material for tissue engineering applications.

14

Analysis of Biodegrability of Degradable/Biodegradable Plastic Material in Controlled Composting Environment

80%

Adamcová D. , Vaverková M. D. , Mašíček T. , Břoušková E.

Journal of Ecological Engineering

|

2016

|

tom Vol. 17, nr 4

1--10

EN

We have obtained eight degradable/biodegradable materials based on starch (certified compostable), sample 4–7, HDPE mixed with totally degradable plastic additive (TDPA), sample 2 and polyethylene with the addition of pro-oxidant additive (d2w), sample 1. Composition of sample 3 has not been reported. The materials have been tested as to the rate and character of their degradability/biodegradability in controlled composting conditions. Experiment explored also the effect of degradation/biodegradation of plastic bags on compost quality. The material of the original samples was subjected to assessment using the Nicolet 6700 FT-IR spectrometer, the outcome thereof was obtaining infrared spectra of the samples. For further specification the original samples were tested using the thermogravimetrical analysis. The texture of the foils at different stages of degradation is presented in the Scanning Electron Microscope (SEM) photographs. Plastic bags certified as compostable have degraded in laboratory conditions and their degradation had no impact on the quality and features of compost. Selected samples (4, 6) showed significant erosion on surface when subjected to the SEM analysis. Samples labeled (by their producers) as 100% degradable (samples 1, 2, 3) did not show any visual signs of degradation and the process of degradation had no impact on the quality and features of compost. Only one of the samples (sample 1) showed certain erosion of surface when submitted for the SEM analysis.

15

Core/Clad Phosphate Glass Fibres Containing Iron and/or Titanium

80%

Ahmed I. , Shaharuddin S. S. , Sharmin N. , Furniss D. , Rudd C.

Biomedical glasses

|

2015

|

tom 1

|

nr 1

EN

Phosphate glasses are novel amorphous biomaterials due to their fully resorbable characteristics, with controllable degradation profiles. In this study, phosphate glasses containing titanium and/or iron were identified to exhibit sufficiently matched thermal properties (glass transition temperature, thermal expansion coefficient and viscosity) which enabled successful co-extrusion of glass billets to form a core/clad preform. The cladding composition for the core/clad preforms were also reversed. Fe clad and Ti clad fibres were successfully drawn with an average diameter of between 30~50 μm. The average cladding annular thickness was estimated to be less than 2 μm. Annealed core/clad fibres were degraded in PBS for a period of 27 days. The strength of the Fe clad fibres appeared to increase from 303 ± 73 MPa to 386 ± 45 MPa after nearly 2 weeks in the dissolution medium (phosphate buffered solution) before decreasing by day 27. The strength of the Ti clad fibres revealed an increase from 236 ± 53 MPa to 295 ± 61 MPa when compared at week 3. The tensile modulus measured for both core/clad fibres ranged between 51 GPa to 60 GPa. During the dissolution study, Fe clad fibres showed a peeling mechanism compared to the Ti clad fibres.

16

Degradation processes in II−VI-compounds-based electron-beam-pumped lasers and creation of material with uniquely high optical strength

80%

Borkovskaya L. V. , Dzhumaev B. R. , Korsunskaya N. E. , Papusha V. P. , Pekar G. S. , Signaevsky A. F.

Opto-Electronics Review

|

1999

|

tom Vol. 7, No. 2

139-143

EN

The processes of gradual degradation as well as the destruction processes of high power electron beam pumped lasers have been studied. The main reason of gradual degradation has been shown to be the increase in dislocation density due to thermoelastic stresses caused by both electron beam treatment and own laser radiation. The types of macrodefects that are responsible for laser screen destruction have been identified. CdS crystals obtained by the method developed by us were shown to have the highest optical strength.

17

Degradacja kwasu moczowego

80%

Świsłocka R.

Zeszyty Naukowe Politechniki Białostockiej. Matematyka, Fizyka, Chemia

|

1998

|

tom Z. 18

111-122

PL

Podjęto badania dotyczace degradacji kwasu moczowego w wodzie metodą pomiaru zaniku badanej substancji. Zbadano również rozkład badanego kwasu w wodach naturalnych oraz wykazano możliwość wykorzystania nadtlenku wodoru i wody chlorowej do usuwania go z wód.

EN

We try to determine degradation of uric acid in water by substance foding method. We also determined useability of hydrogen peroxide and chlorine water for removing uric acid from water.

18

Stability-indicating high-performance thin-layer chromatographic method for analysis of terbinafine in pharmaceutical formulations

80%

Ahmad S. , Jain G. K. , Faiyazuddin M. , Iqbal Z. , Talegaonkar S. , Sultana Y. , Ahmad F. J.

Acta Chromatographica

|

2009

|

tom Vol. 21, no. 4

631--639

EN

A new, simple, selective, precise, robust and stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been established for analysis of terbinafine hydrochloride (TH) in the bulk drug and in pharmaceutical formulations. Separation was achieved on aluminium plates precoated with silica gel 60F 254 , with toluene-ethyl acetate-formic acid 4.5:5.5:0.1 ( v/v ) as mobile phase. Densitometric analysis was performed at 284 nm. Compact bands of TH were obtained at R F 0.31 ± 0.02. Linearity ( r 2 = 0.9985), limit of quantification (35 ng per band), recovery (97.6−101.6%), and precision (≤2.19) were satisfactory. The method was applicable for routine analysis and accelerated stability testing of TH in pharmaceutical drug-delivery systems. Because the method can effectively separate the drug from its degradation products, it can be used as a stability-indicating method.

19

Fracture of metals: the effect of microstructure degradation.

80%

Kurzydłowski K.

Prace Naukowe Instytutu Materiałoznawstwa i Mechaniki Technicznej Politechniki Wrocławskiej. Konferencje

|

2007

|

tom Vol. 65, nr 11

47-54

EN

Engineering materials are susceptible to environmental degradation. In industrial practice, the degradation is always a negative phenomenon. In bioengineering, the degradation may be undesirable (e.g. corrosion of metallic implants, wear of artitlcial joint implant) or desirable (biodegradable devices and tissue engineering). In both cases, the knowledge of the kinetics of degradation is crucial for safe use of materials. The methods for predicting remaining life commonly used in industrial practice will be presented in the context of metals. Non destructive techniques for monitoring degradation will be discussed and some ideas about their application proposed.

PL

Materiały mają swój duży udział w rozwoju cywilizacji przemysłowej. Szeroka wiedza na temat mikrostruktury i właściwości materiałów jest gromadzona w oparciu o badania z zakresu inżynierii materiałowej. Znajomość materiałów jest szczególnie istotna w sektorze przemysłowym, w tym w transporcie (lotnictwo) i przemyśle energetycznym (elektrownie jądrowe ), które to gałęzie wymagają długotrwałego, ciągłego działania przy zachowaniu wysokich standardów bezpieczeństwa. Analiza zjawiska pękania jest bardzo ważna dla oceny wytrzymałości materiałów. Wiele badań prowadzonych jest w celu rozwoju metod pomiaru i oceny odporności na pękanie metali. Do analizy rzeczywistych struktur i właściwości elementów w warunkach pracy, szczególnie polecane są metody nieniszczące. Wyniki ciągłego monitorowania mogą być następnie użyte do przewidywania procesów pękania nowoczesnymi metodami symulacji komputerowej.

20

Reakcja tkanek miękkich na produkty degradacji biomateriałów węglowych - badania histochemiczne

80%

Menaszek E. , Zamorska L. , Żołnierek M. , Błażewicz M.

Inżynieria Biomateriałów

|

2003

|

tom R. 6, nr 29

23-26

PL

Procesy regeneracji tkanek miękkich w obecności implantów biomateriałów węglowych trzech typów badano przy użyciu metod histochemicznych. Biomateriały w postaci proszku, wszczepione do tkanki mięśniowej szczura nie powodowały upośledzenia czynności komórek wyrażających się aktywnością enzymów głównego szlaku metabolicznego oraz procesów regeneracji tkanek.

EN

The regeneration processes of soft tissue in the presence of carbon biomaterials implants of three types were investigated using histochemical methods. Biomaterials in the form of powder, implanted into the rat muscle did not cause a disadvantage of cells functions expressed by the activity of main enzymes of metabolic pathway and by the tissue regeneration processes.