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The role of lamellate phospholipid bilayers in lubrication of joints

Pawlak Z., Urbaniak W., Gadomski A., Yusuf K.Q., Afara I.O., Oloyede A.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 4

101-106

EN

This study aims to determine the effect of progressive loss of the surface active phospholipids on the characteristics, and hence tribological function of articular cartilage. In accordance to Hill's hypothesis, 3-7 lipid bilayers at pH 7.4 operate as the solid lubricant in the cartilage-cartilage interface during physiological function. These bilayers are known to be depleted during cartilage degeneration. This study models this loss of phospholipid bilayers, studying experimentally both wet and dry cartilage surfaces, measuring surface wettability, and friction coefficient under a constant stress of 1.2 MPa. The results demonstrate that the friction coefficient increases gradually with loss of the phospholipid bilayers, and gains in value with decrease in wettability.

2

Lead Leachability from Shooting Range Soils

Rauckyte T., Żak S., Pawlak Z., Oloyede A.

Ecological Chemistry and Engineering. A

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2009

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Vol. 16, nr 4

419-426

EN

Lead contamination of soil in shooting ranges creates an environmental problem. Samples of soil were analyzed for total lead (T-[Pb]) and extracted lead (TCLP-[Pb]) using toxicity characteristic leaching procedure (TCLP). Total content of lead in soil samples varied from 640 to 4600 ppm. The TCLP test indicated that lead in most of soil samples exceeded the 5 ppm, a critical level of EPA regulation for solid and hazardous waste. The ratios of leaching lead (TCLP-[Pb]) to total lead (T-[Pb]) in soil samples ranged from 1.9 % to 5.2 %. The TCLP extracts from soil samples indicated lead concentration levels of 5 to 45 times over the US EPA regulatory level of 5 ppm and this was characterized as a toxic waste.

PL

Problem środowiskowy stanowi zanieczyszczenie na terenie strzelnic gleby ołowiem. Analiz próbki gleby na zawartość ołowiu ogółem i ekstrahowanego, wykorzystując metodę ługowania TCLP. Ogólna zawartość ołowiu w próbkach glebowych wahała się od 640 do 4600 ppm. Test TCLP wskazał, że, w większości próbek glebowych przewyższył 5 ppm, co dla stałych/trwałych niebezpiecznych oznacza poziom krytyczny według regulacji EPA. W próbkach gleby stosunek ługowanego ołowiu do ołowiu ogółem waha się od 1,9 % do 5,2 %. Ekstrakty TCLP z próbek glebowych wykazały poziom stężenia ołowiu od 5 do 45 razy przewyższający poziom 5 ppm, określony przez amerykańską regulację EPA i gleby z terenu strzelnic oceniono jako toksyczne.

3

Oil, grease and used petroleum oil management and environmental economic issues

Pawlak Z., Rauckyte T., Oloyede A.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 26, nr 1

11-17

EN

Purpose: This paper undertakes to answer the question of how used petroleum oil and grease enter groundwater or to the drain becoming both environmental and economic problems to utility companies. Design/methodology/approach: Laboratory methodology was based on modern instrumentation validated further with experimental investigation. Petroleum-contaminated soil samples were analyzed for oil and grease (O/G) content, total petroleum hydrocarbons (TPH), and volatile aromatic compounds: benzene, toluene, ethylbenzene, and xylenes (BTEX) and naphthalene. Gas chromatography-Mass Spectrometry (GC/MS) was used to analyse BTEX and naphthalene analytes. Findings: The results show that total petroleum hydrocarbon fraction (TPH) accounted for oil and grease (O/G) and the ratio of [TPH]/[O/G] ranged from 12% to 50%. The results of volatile organic fraction (BTEX) accounted for only a small part of total TPH and the ratio of [BTEX]/[TPH] ranged below 1%. The concentration of four samples for TPH test exceeded the regulatory limit of 500 ppm for hydrocarbons. The gas chromatography-flame ionization detector (GC-FID) method appear to offer the best basis for standard TPH test in soil and groundwater verification of site cleanup. Research limitations/implications: In the future it will be possible to apply the procedures to other more complicated cases e.g. used oil containing more than 1000 ppm total halogens, which is regulated as hazardous waste. Practical implications: Promising directions for adaptation of appropriate pre-treatment standard processes for recycling programs, pollution prevention and reduction of maintenance cost. Originality/value: The gas chromatography-flame ionization detector (GC-FID) methods appear to offer the best hope for standard TPH test in soil and groundwater verification of site cleanup. Implementation of management standards and a permit policy for O/G and used oil generators will be issued to each facility.

4

A biochemical model for characterising the surface-active phospolipid bilayer of articular cartilage relative to acid-base equilibrium

Pawlak Z., Kotynska J., Figaszewski Z., Gadomski A., Gudaniec A., Oloyede A.

Archives of Materials Science and Engineering

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2008

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Vol. 29, nr 1

24-29

EN

Purpose: This paper, addresses the question of how changes in acid - base equilibrium influence change in the charge density of the phospholipid bilayer on articular cartilage surfaces during lubrication. Design/methodology/approach: Liposomes have been used to mimic biological phospholipid membranes on articular cartilage surface where proteins are bounded, ions are transported, energy is transducted, and cellular processes take place. The charge density of the membrane was determined as a function of pH and electrolyte concentration from the microelectrophoretic method. Liposome membrane was prepared as an aqueous solution of NaCl under various pH conditions. Microelectrophoresis was used to examine the local acid-base equilibrium of the electrolytes with the membrane surface, which can be considered to model the phospholipids interface in articular cartilage. Findings: The adsorbed ions (H+, OH-, Na+, Cl-) which are present in the electrically charged solutions of liposome membrane comprising phosphatidycholine (PC), were found to exhibit pH-responsive quasi-periodic behavior. Research limitations/implications: We have established that the acid-base dissociation behavior in phospholipid bilayers of articular cartilage is a key to understanding biolubrication processes. For example,previous investigators found that the formation of the multilayer of polyisopeptide/hyaluronic acid depends on surface properties such as film thickness, surface friction, surface wetability; wetness and swelling behavior. Future work should consider the adsorption of polyelectrolyte ions, e.g., the glycoprotein lubricin and hyaluronan, on the liposome membrane surface in the presence of H+ and OH- ions. Originality/value: A novel model of the joints’ phospholipid bilayers has been created using liposome membrane This model can be applied in the investigation of polyelectrolyte ions such as lubricin, in articular cartilage. We have demonstrated that the acid-base processes on charged surfaces is a key mechanism in facilitating lubrication in human joints.

5

Impact of the charge density of phospholipid bilayers on lubrication of articular cartilage surfaces

Pawlak Z., Kotynska J., Figaszewski Z. A., Oloyede A., Gadomski A., Gudaniec A.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 23, nr 1

47-50

EN

Purpose: We attempt to answer the question how some changes in acid - base equilibrium have an impact on the charge density of a phospholipid bilayer formed during lubrication occurring at articular cartilage surfaces. Design/methodology/approach: Liposomes have been used to mimic biological phospholipid membranes on articular cartilage surface where proteins are bounded, ions are transported, energy is transducted, and cellular processes are taking place. The charge density of the membrane was determined as a function of pH and electrolyte concentration from the microelectrophoretic method. Liposome membrane has been prepared as an aqueous solution of NaCl under various pH conditions. Microelectrophoresis was used to examine the local acid-base equilibrium of the electrolytes with the membrane surface, which can be considered to be an interface of phospholipids in articular cartilage. Findings: The effects of the adsorption of ions (H+, OH- ; Na+, CI-), which are present in solution upon electric charge of the liposome membrane assembled of phosphatidycholine (PC), have also been found to exhibit pH-responsive (quasi-periodic) behavior. Research limitations/implications: We hypothesized that the acid-base dissociation behavior in phospholipid bilayers of articular cartilage is a key to understanding biolubrication processes. For example, similar previous investigators found that the behavior of a multilayer made of polyisopeptide/hyaluronic acid depends on some of the surface properties such as film thickness, surface friction, surface wetness and swelling conditions. Future work should consider the adsorption of polyelectrolyte ions, e.g., the glycoprotein lubricin and hyaluronan, at the liposome membrane surface involved, assumed that besides the H+ and OH- ions, the polyelectolyte ions were also engaged. Originality/value: This liposome membrane is a model for phospholipid bilayers and will be applied for the investigation of polyelectrolyte ions, e.g. lubricin, in articular cartilage conditions. We demonstrate that knowledge on the acid-base processes on charged surface is the key to understanding phenomena occurring at interfaces in human joints lubrication, thus pointing to the biolubrication as a charged interface-controlled process.