Cement fixed hip prosthesis polymer bearing wear and measurement of it using computerized method

Lonkan tekonivelten käyttö on yleistynyt Suomessa ja maailmalla huomattavasti, asennusmäärien ollessa jatkuvasti kasvussa. Tämä johtuu sekä väestön ikääntymisestä että keskimääräisen eliniän jatkuvasta kasvusta. Lonkan tekonivelleikkausten yleistyminen johtaa väistämättä merkittäviin taloudellisiin kustannuksiin. Tekonivelen liukuparin ja sen kulumasta syntyvien kulumapartikkeleiden biologinen vaste vaihtelee merkittävästi materiaaliryhmittäin. Erityisesti viimeisen vuosikymmenen aikana liikunnallisesti aktiivisille potilaille on asennettu metalli-metalli liukuparillisia lonkan tekoniveliä. Kyseisten implanttien kulumapartikkelit ovat osoittautuneet elimistölle erittäin haitallisiksi. Tämä on johtanut metalli-metalli liukuparisten implanttien käyttökieltoon Suomessa ja maailmalla. Metalli-polymeeri, keraami-polymeeri ja keraami-keraami liukupariset tekonivelet kuluvat myös, mutta niiden kulumapartikkeleiden biologisen vasteen on todettu olevan merkittävästi lievempi. Työn kirjallisuusosassa on esitetty syyt lonkan tekonivelleikkauksille, esitelty lonkan anatomiaa sekä käyty läpi alan kirjallisuudesta löytyvää lonkan mekaanista kuormitustietoa. Lisäksi on esitelty yleiset liukuparimateriaalit ja niiden ominaisuudet. Lääkäreitä on kerätty yleisiä suosituksia eri liukuparien asentamisesta erityyppisille potilaille. Työn kokeellisessa osassa mitattiin metalli-polymeeriliukuparisten lonkan tekonivelten kulumaa EBRA-menetelmällä (Einzel Bild Röntgen Analyse), sekä kuvattiin liukupintoja pyyhkäisyelektronimikroskoopilla (SEM). Työn aikana seurattiin myös lukuisia tekonivelleikkauksia, jotta implantologian kliininen puoli tulisi tutuksi. Mittaustulosten perusteella liukupinnassa havaittiin vuosittain suurimmillaan noin 0,25 mm lineaarinen kuluma. Tulokset ovat yhtenevät alan kirjallisuudesta löytyvien tulosten kanssa, eikä tämän tutkimuksen perusteella voida esittää syitä siihen, että metalli-polymeeriliukupariset tekonivelet olisivat sopimattomia lonkan tekonivelsovelluksiin. Tässä työssä tarkastellaan erityisesti kulumamittausjärjestelmien tarkkuutta, joka on usein sivuutettu alan kirjallisuudessa. Koska lähes kaikki kulumamittaukset on tehty tavallisista AP-röntgenkuvista (Anterior-Posterior) mittaustarkkuus huomioimatta, ovat tulokset huomattavasti epätarkempia kuin alan julkaisuissa esitetään. Tässä työssä perustellaan syyt mittausten epätarkkuudelle sekä käsitellään vaihtoehtoisia mittausmenetelmiä. Yhteenvetona voidaan todeta, että työssä on osoitettu EBRA-menetelmän sopivan lonkan tekonivelten kulumamittauksiin, mutta vain jos mittaukseen liittyvät epätarkkuudet otetaan riittävällä tavalla huomioon. Lopuksi todetaan lonkan tekonivelen toiminnan riippuvan merkittävästi asennosta johon se on asennettu.Installation rate of prosthetic implants in Finland and worldwide has been and is still increasing. This is due to population aging and increase in lifespan. These factors lead to significant costs. Biological reaction to the wear and wear particles from prosthetic implants depends significantly on the materials used in the bearing couple. Within the last decade a lot of metal-on-metal bearing couple hip prostheses have been installed to physically active patients. Wear particles from these bearing couples have been found to be harmful to the patients. Due to this metal-on-metal hip prostheses have been banned from use. Metal-on-polymer, ceramic-on-polymer and ceramic-on-ceramic bearing couples also generate wear particles under loading, but the biological effects of these particles are significantly less severe. In the literature part of this work the reasons leading to total hip replacements, anatomy and biomechanics of the hip as well as loads in the hip joint reported in the literature have been displayed. By interviewing doctors general guidelines of selecting the materials used in total hip replacements for different patients has been established. In the experimental part of the work wear measurements using EBRA-method (Einzel Bild Röntgen Analyse) from metal-on-polymer bearing couple are reported. Scanning electron microscope (SEM) pictures from bearing surfaces are provided as well. During the work multiple surgeries were followed to understand the clinical side of the implantology. Wear measurements show that the metal-on-polymer bearing couple suffers from maximum of 0,25 mm linear wear yearly. Results found are in line with those from the literature. Based on this study there is no evidence to claim that metal-on-polymer bearing couple prostheses would be insufficient in total hip replacement prostheses. This work concentrates in the errors found in the wear measurements that have been ignored in many parts in the literature. Since majority of the wear measurements found from literature are done from AP-radiographs (Anterior-Posterior) without taking in account errors in the measurements, the results in these publications are not as accurate as the publishers report. In this work reasons for the errors in the measurements are documented and alternative ways of measuring the wear are given. It can be concluded that EBRA-method is valid tool for measuring wear in metal-on-polymer bearing couples as long as the errors affecting the measurements are taken in account. It must be noted that functionality of the prosthetic hip depends significantly from the position that it is installed to

Aikuisen ADHD:n tunnistaminen ja merkitys

ADHD on kehityksellinen tarkkaavuuden, toiminnanohjauksen ja impulssikontrollin säätelyn vaikeus, joka usein jatkuu läpi elämän heikentäen työ- ja toimintakykyä. ADHD johtaa tavallisesti alisuoriutumiseen opinnoissa ja työelämässä. Tyypillisiä ongelmia ovat heikentynyt työteho, lisääntyneet sairauspoissaolot ja suurentunut työtapaturmariski. Työterveyshuolto on keskeisessä asemassa työelämässä olevien potilaiden tunnistamisessa ja tutkimuksiin ohjaamisessa. Lääkehoidolla on osoitettu olevan hyvä teho aikuispotilaiden keskeisiin oireisiin sekä työ- ja toimintakykyyn. Hoito on erittäin kustannustehokasta ja voidaan yhdistää psykososiaalisiin hoitomuotoihin.Peer reviewe

Laatusiemenen tuotannon ja käytön tehostaminen: tiedoista tekoihin LAATUSIEMEN 2012-2015

Luken kirjat, raportit, oppaat ja esitteet. Loppuraportti201

Polyacrylonitrile-encapsulated amorphous zirconium phosphate composite adsorbent for Co, Nd and Dy separations

Recycled Nd and Dy from the end-of-life NdFeB permanent magnet is an important supplement for the increasing demand of rare-earth elements. Thus, there is an urgent need to develop an environmentally friendly recycling method. Amorphous zirconium phosphate exhibits selective separation properties towards the ternary Co-Nd-Dy system, however, its powdery form limits development of scaled-up applications. We present an efficient amorphous ZrP/Polyacrylonitrile (am-ZrP/PAN) composite ion exchanger for uptake and separation of Nd, Dy and Co. The am-ZrP/PAN composite was synthesized and its structural, morphologic and acidic properties were investigated by various methods. X-ray tomography revealed rather evenly distributed am-ZrP in the PAN polymer matrix. The selectivity and ion-exchange kinetics of the am-ZrP/PAN composite were determined in relation to the individual elements. Due to dimethylformide (DMF) intercalation into the interlayer of ZrP, the uptake of Co, Nd and Dy increased 50% compared with that of the pristine am-ZrP. Column separation of Co, Nd and Dy from the Co-Nd-Dy ternary system was assessed by varying the feed concentration, loading degree, temperature, running speed and elution agent (HNO3) concentration. Finally, gradient elution was employed for Co, Nd and Dy separation from a simulated ternary leachate. Fractions with 87.9% pure Co, 96.4% pure Nd and 40% pure Dy were collected through a single-column operation.Peer reviewe

Selective detection of morphine in the presence of paracetamol with anodically pretreated dual layer Ti/tetrahedral amorphous carbon electrodes

We investigated the effect of anodic treatment of titanium/tetrahedral amorphous carbon electrodes on the electrochemical detection of morphine and paracetamol. The anodic treatment caused both oxidation of the carbon and, more importantly, exposure and oxidation of the underlying Ti layer. This treatment anodically shifted the oxidation potential of paracetamol while that of morphine remained unaffected. The resulting electrode also showed better selectivity than a ta-C electrode without Ti. After anodic treatment at 2.5 V, selective detection of morphine with a physiologically meaningful detection limit of 9.8 nM and a linear range of 0.1-10 mu M was obtained in the presence of 100 mu M paracetamol.Peer reviewe

Effect of Liquid Electrolyte Soaking on the Interfacial Resistance of Li7La3Zr2O12 for All-Solid-State Lithium Batteries.

The impact of liquid electrolyte soaking on the interfacial resistance between the garnet-structured Li7La3Zr2O12 (LLZO) solid electrolyte and metallic lithium has been studied. Lithium carbonate (Li2CO3) formed by inadvertent exposure of LLZO to ambient conditions is generally known to increase interfacial impedance and decrease lithium wettability. Soaking LLZO powders and pellets in the electrolyte containing lithium tetrafluoroborate (LiBF4) shows a significantly reduced interfacial resistance and improved contact between lithium and LLZO. Raman spectroscopy, X-ray diffraction, and soft X-ray absorption spectroscopy reveal how Li2CO3 is continuously removed with increasing soaking time. On-line mass spectrometry and free energy calculations show how LiBF4 reacts with surface carbonate to form carbon dioxide. Using a very simple and scalable process that does not involve heat-treatment and expensive coating techniques, we show that the Li-LLZO interfacial resistance can be reduced by an order of magnitude

New electrochemically improved tetrahedral amorphous carbon films for biological applications

Carbon based materials have been frequently used to detect different biomolecules. For example high sp3 containing hydrogen free diamond-like carbon (DLC) possesses many properties that are beneficial for biosensor applications. Unfortunately, the sensitivities of the DLC electrodes are typically low. Here we demonstrate that by introducing topography on the DLC surface and by varying its layer thickness, it is possible to significantly increase the sensitivity of DLC thin film electrodes towards dopamine. The electrode structures are characterized in detail by atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM) as well as by transmission electron microscopy (TEM) combined with electron energy loss spectroscopy (EELS). With cyclic voltammetry (CV) measurements we demonstrate that the new improved DLC electrode has a very wide water window, but at the same time it also exhibits fast electron transfer rate at the electrode/solution interface. In addition, it is shown that the sensitivity towards dopamine is increased up to two orders of magnitude in comparison to the previously fabricated DLC films, which are used as benchmarks in this investigation. Finally, it is shown, based on the cyclic voltammetry measurements that dopamine exhibits highly complex behavior on top of these carbon electrodes.The authors T.L, V.P., S.S., T.P., and J.K., would like to acknowledge the National Agency for Technology and Innovation (grant number 211488) and Aalto University (grant number 902380) for the financial support

Electrochemical reactions of catechol, methylcatechol and dopamine at tetrahedral amorphous carbon (ta-C) thin film electrodes

The electrochemical reactions of dopamine, catechol and methylcatechol were investigated at tetrahedral amorphous carbon (ta-C) thin film electrodes. In order to better understand the reaction mechanisms of these molecules, cyclic voltammetry with varying scan rates was carried out at different pH values in H2SO4 and PBS solutions. The results were compared to the same redox reactions taking place at glassy carbon (GC) electrodes. All three catechols exhibited quasi-reversible behavior with sluggish electron transfer kinetics at the ta-C electrode. At neutral and alkaline pH, rapid coupled homogeneous reactions followed the oxidation of the catechols to the corresponding o-quinones and led to significant deterioration of the electrode response. At acidic pH, the extent of deterioration was considerably lower. All the redox reactions showed significantly faster electron transfer kinetics at the GC electrode and it was less susceptible toward surface passivation. An EC mechanism was observed for the oxidation of dopamine at both ta-C and GC electrodes and the formation of polydopamine was suspected to cause the passivation of the electrodes.Authors wish to acknowledge the financial support by the Finnish Parkinson Foundation (T.P.), the Finnish Funding Agency for Innovation (grant number 211488) (T.P., S.S. and T.L.), the Academy of Finland (grant number 285015) (T.L.) and MINECO project CTQ2013-44083-P (J.F.M.)