Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies.

It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies

Environmental impact assessment of surface mining

W pracy przedstawiono doświadczenia autorów w ocenie przedsięwzięć z obszaru górnictwa zasobów mineralnych. Są one przedstawione na podstawie dwóch przykładów. Pierwszy dotyczy mniejszych przedsięwzięć wydobycia piasku, które są rozmieszczone na terenie całej Republiki Czeskiej. Drugi aspekt podejmuje problematykę oceny wpływu na środowisko przedsięwzięć zwiększenia wydobycia węgla brunatnego, w już istniejących kopalniach (w południowych i południowo-zachodnich Czechach).The paper summarizes up author´s experience with the environmental impact assessment process in the branch of surface mining of raw materials. Experience is demonstrated in two case studies. The first case study is from branch smaller plans - extraction of stone and sand. The paper deals hereafter with impacts of mining of brown coal (large plans) on environment. The assessment of environmental impacts of brown coal mine will be demonstrated in assessing of effects of one of the biggest brown coal mine in the Czech Republic, which is situated in northern part of Bohemia

Możliwości technologii zgazowania i pirolizy w dziedzinie odzyskiwania energii z odpadów

The article summarizes possibilities of energy recovery from waste (first of all from municipal waste and tyres). Attention is given to technologies which can be, besides classical grate boilers, used for energy recovery from waste. These include gasification and pyrolysis units. There are emission values that were measured on the pyrolysis equipment of a new construction. The equipment is being prepared for practical use at present. The equipment more or less fulfils both emission limits valid in the Czech Republic and the emission standards of the European Union. The conclusion of this contribution is devoted to the current and future situation in the area of energy recovery from waste in the Czech Republic.Artykuł podsumowuje możliwości odzysku energii z odpadów (przede wszystkim z odpadów komunalnych i opon).Uwagę zwrócono na technologie, inne niż klasyczne stosowane kotły rusztowych, stosowane do odzysku energii z odpadów. Należą do nich instalacje zgazowania i pirolizy. Przedstawiono wartości emisji , które zostały zmierzone w urządzeniu do pirolizy nowej konstrukcji. Aktualnie instalacja jest przygotowana do wdrożenia praktycznego. Instalacja spełnia limity emisji zarówno w Czechach jak i normy emisji Unii Europejskiej. Celem artykułu było kierunków rozwoju technologii odzysku energeii z odpadów w instalacjach w Republice Czeskiej

The zeta potential of laolin suspensions measured by electrophoresis and electroacoustics

Zeta potenciál zředěných a koncentrovaných kaolinových disperzí byl pozorován metodou elektroforézy a elektroakusticky. Vliv přídavku soli (KCl), a polymerního materiálu (Triton X-100) a anionického tenzidu (Sodium dodecylsulfátu, SDS) na vlastnosti suspenze byl studován elektroforetickými metodami. Elektroakustické metody byly použity pro měření zeta potenciálu pro nejvyšší možné koncentrace kaolinu v suspenzi a byl pozorován také vliv zřeďování. Vliv stárnutí čerstvě připravených vzorků a izoelektrický bod kaolinu byly také studovány. Použitím obou technik bylo zjištěno, že pro tento typ disperzí nebyl detegován izoelektrický bod, jenom maximum v hodnotě zeta potenciálu pro suspenzi kaolinu. Tato maxima byla pozorována také po přídavku Triton X-100 a SDS. Se zvyšující se koncentrací KCl a SDS ve vodní suspenzi se tato maxima posouvají více do kyselé oblasti, přičemž v přítomnosti Triton X-100 se poloha maxima zeta potenciálu nemění a zůstává konstantní. Elektroakustickými technikami bylo zjištěno, že čerstvě připravené koncentrované suspenze vyžadují kolem 6 hodin pro ustálení hodnoty zeta potenciálu. Zřeďování koncentrovaných suspenzí vedlo ke snížení zeta potenciálu tím, že ionty se vážou na desorbovaný povrch, čímž stlačují povrchový náboj. Maxima zeta potenciálu zůstala nezměněna také po zahřátí prášku v žíhací peci při teplotě 200°C (pro odstranění organických zbytků), což naznačuje nejmožnější vysvětlení vzniklých maxim jako důsledek izomorfní substituce.The zeta potentials of kaolin dilute and concentrated suspensions were monitored using the techniques of electrophoresis and electroacoustics, respectively. The effect of addition of salt (KCl), a polymer material (Triton X-100), and an anionic surfactant (sodium dodecyl sulphate, SDS) on the suspension properties was investigated by electrophoresis. Electroacoustics was employed for the measurement of zeta potentials for the highest possible kaolin content in suspension and the effect of dilution. The effect of aging of a freshly prepared sample and kaolin isoelectric point was also studied. Using both techniques it was noted that there was no isoelectric point, just a maximum value in the magnitude of the kaolin suspension zeta potential. These maxima were observed also in the presence of Triton X-100 and SDS. An increase of the concentration of KCl and SDS in suspension shifted the maxima towards more acidic values, while in the presence of Triton X-100 the position of the zeta potential maxima remained constant. Electroacoustic techniques revealed that a freshly prepared concentrated suspension requires about six hours to equilibrate to achieve a steady zeta potential. Diluting the concentrated suspensions led to decrease of the zeta potential as ions bound to the surface desorbed and screened the surface charge. The zeta potential maxima remained unchanged even after heating the powder in an oven at 200 degrees C (to remove any organic material) thereby suggesting that the most likely explanation for the maxima is isomorphic substitution

Plasma surface modification of polyethylene

Oxidative (oxygen and air) RF-plasma treatment of HDPE was found as an effective tool for improving wettability, as well as for increasing its surface micro-hardness. The latter plasmas generate wide range of reactive species in the system, which undergo consecutive chemical reactions, creating thus several oxygen based functionalities at the interface (carbonyl, carboxyl, ether, peroxide etc.) as were detected by ATR FTIR and XPS analysis. An increased negative surface charge of plasma treated polyethylene (PE) confirms the presence of functional ionogenic groups containing oxygen. Simultaneously, the vigorous increase of the surface roughness was found as a result of the successful plasma etching.EC - HPMT-GH-00- 00206-0