Increase In Ion Concentration Research Articles

PH Switchable Electrochemical and Optical Properties of Polyoctylthiophene – Pyrene Composites

AbstractPolyoctylthiophene electrochemical and optical properties are dependent on the polymer oxidation state, generally requiring presence of doping ions. In this work polyoctylthiophene composites with pyrene or aminopyrene have been prepared and studied using optical and electrochemical methods. It is shown that in the composite formed pyrene molecules act as molecular dopant for the conducting polymer, resulting in a system of partially oxidized polythiophene backbone, yet of high lipophilicity. On the other hand, composite of aminopyrene with polyoctylthiophene is characterized with pH dependent electrochemical and optical properties. The difference arises mostly from the protonation/ deprotonation reaction occurring for aminopyrene embedded in polyoctylothiophene. Nanoparticles of polythiophene‐aminopyrene show turn‐on emission dependence on increase of hydrogen ions concentration in solution in a wide pH range from 12 to 5. For low pH high emission activity is observed for nanoparticles, whereas for films high lipophilicity and low electrochemical activity pointing to presence of semiconducting polymer in the system for protonated aminopyrene. For high pH, when deprotonation of aminopyrene is observed, the system is characterized with low optical, yet high electrochemical activity and low lipophilicity. The electrochemical activity of polyoctylthiophene‐aminopyrene composite can be reversibly switched simply by solution pH change.

Blood Metal Ion Release After Primary Total Knee Arthroplasty: A Prospective Study.

ObjectivesTo investigate the course of in vivo blood metal ion levels in patients undergoing primary total knee arthroplasty (TKA) and to investigate potential risk factors associated with metal ion release in these patients.MethodsTwenty‐five patients with indication for TKA were included in this prospective study. Whole blood metal ion analysis was performed pre‐operatively and at 1 week, 6 weeks, 3 months, 6 months, and 12 months postoperatively. Clinical scores were obtained using the American Knee Society Score (AKSS) and the Oxford Knee Score (OKS) at each follow‐up and patientsʼ activity levels were assessed by measuring the mean annual walking cycles at 12 months follow‐up. Anteroposterior and lateral radiographs of the operated knee were evaluated postoperatively and at 12‐month follow‐up with regard to implant position and radiological signs of implant loosening. Correlation analysis using multivariate linear regression was performed to investigate the influence of different variables (age, gender, functional scores, number of walking cycles, and body mass index [BMI]) on blood cobalt ion concentrations.ResultsMean metal ion levels of cobalt, chromium, molybdenum, and titanium were 0.28 μg/L (SD, 0.14), 0.43 μg/L (SD, 0.49), 0.62 μg/L (SD, 0.45), and 1.96 μg/L (SD, 0.98), respectively at 12‐month follow‐up. Mean cobalt ion levels significantly increased 1‐year after surgery compared to preoperative measurements. There was no statistically significant increase of mean metal ion levels of chromium, titanium, and molybdenum at 1‐year follow‐up. Overall, metal ion levels were low and no patient demonstrated cobalt ion levels above 1 μg/L. Postoperative radiographs demonstrated well‐aligned TKAs in all patients and no signs of osteolysis or implant loosening were detected at 1‐year follow‐up. Both the AKSS and OKS significantly improved during the course of the study up to the final follow‐up. Multivariate regression analysis did not show a statistically significant correlation between the tested variables and blood cobalt ion concentrations.ConclusionA statistically significant increase of mean cobalt ion concentration at 1‐year follow‐up was found in this cohort of patients with well‐functioning TKA, although overall blood metal ion levels were relatively low. Despite low systemic metal ion concentrations seen in this cohort, the local effects of increased metal ion concentrations in the periprosthetic environment on the long‐term outcome of TKA should be further investigated.

Theoretical investigation of electroviscous flows in hydrophilic slit nanopores: Effects of ion concentration and pore size

Nanopores with various shapes are well developed in unconventional reservoirs, and the transport phenomena of solutions in these reservoir rocks are ubiquitous but have not yet been fully understood. This article investigates the flow characteristics of solutions in hydrophilic slit nanopores through the combination of a modified Poisson–Boltzmann (MPB) model and the modified Navier–Stokes (NS) equation. To account for the nanoconfinement effects on ion concentration and fluid viscosity, an electrochemical potential term is used in the MPB model and a varying viscosity model (VVM) is introduced in the NS equation. The model rationality is first confirmed, and then the influences of ion concentration and pore size on the transport capacities of solutions in nanopores are illuminated. In addition, the hydrodynamic features of liquids in nanopores and the limitations of this coupled model are discussed as well. The results show that the dimensionless apparent permeability of the slit increases with an increase in ion concentration and pore size. The relative contributions of the electroviscous effect (EVE) and VVM to the total flow resistance reveal different varying trends as ion concentration or pore size increases, which is greatly related to the surface charge density and the sign of the charged wall. Additionally, although the effects of EVE and VVM resulting from the nanoconfinement are considered, average velocities of fluids in nanopores exhibit a linear correlation with the pressure gradient, which cannot be used to explain the nonlinear flow mechanism occurring in tight reservoirs. Furthermore, we also compare the velocity difference between the classical PB and MPB models. We hope that the findings in this work can help improve our understanding of the characteristics of liquid flow in tight reservoirs and provide vital practical implications for diverse engineering applications.

The inflammatory pseudotumor formed after metal-on-metal hip arthroplasty

Due to its advantages of low wear, high stability and flexibility, the new generation metal-on-metal hip prosthesis is favored by many patients with hip diseases, especially young patients. However, in recent years, several studies have indicated that adverse reactions to metal debris (ARMD) caused the formation of inflammatory pseudotumor, which ultimately led to a higher revision rate after metal-on-metal hip arthroplasty. This aroused the widespread concern from doctors and patients. Moreover, revision surgery for metal-on-metal hip arthroplasty in the setting of inflammatory pseudotumor is faced with a great risk of failure because of the large defects of bone and surrounding soft tissue and difficulty in removing the original prosthesis and the fixing of the modified prosthesis. Therefore, the use of such products is restricted with caution in their choice. We summarized the recent developments in the research in the risk factors, diagnosis and treatment of inflammatory pseudotumor after metal-on-metal hip arthroplasty. The risk factors for the formation of inflammatory pseudotumor around the hip prosthesis mainly include the increase of metal ion concentration, the position of prosthesis implantation and the patient's own factors. The diagnosis mainly depends on physical examination, imaging examination, laboratory examination, arthroscopy and histological examination. The treatment strategies for clinical symptomatic and asymptomatic patients are also varies. Through the detailed analysis, evaluation and summary of the above contents, we may provide guidance for the selection of hip prosthesis, and lay the foundation for further exploration of the mechanism of inflammatory pseudotumor caused by ARMD.

Modulation of the catalytic activity of a metallonuclease by tagging with oligohistidine

Peptide tags are extensively used for affinity purification of proteins. In an optimal case, these tags can be completely removed from the purified protein by a specific protease mediated hydrolysis. However, the interactions of these tags with the target protein may also be utilized for the modulation of the protein function. Here we show that the C-terminal hexahistidine (6 × His) tag can influence the catalytic activity of the nuclease domain of the Colicin E7 metallonuclease (NColE7) used by E. coli to kill competing bacteria under stress conditions. This enzyme non-specifically cleaves the DNA that results in cytotoxicity. We have successfully cloned the genes of NColE7 protein and its R447G mutant into a modified pET-21a DNA vector fusing the affinity tag to the protein upon expression, which would be otherwise not possible in the absence of the gene of the Im7 inhibitory protein. This reflects the inhibitory effect of the 6 × His fusion tag on the nuclease activity, which proved to be a complex process via both coordinative and non-specific steric interactions. The modulatory effect of Zn2+ ion was observed in the catalytic activity experiments. The DNA cleavage ability of the 6 × His tagged enzyme was first enhanced by an increase of metal ion concentration, while high excess of Zn2+ ions caused a lower rate of the DNA cleavage. Modelling of the coordinative effect of the fusion tag by external chelators suggested ternary complex formation instead of removal of the metal ion from the active center.

Adsorption of triclosan onto different aged polypropylene microplastics: Critical effect of cations

Adsorption of organic contaminants onto aged microplastics (MPs) may be important in understanding their transport potential and ecological risks in aquatic environment. Cations of Na+ and Ca2+ are common electrolytes in water, which can greatly influence the adsorption behavior of MPs by impacting the electrostatic interaction between MPs and organic contaminants. The results of this study showed that aged isotactic polypropylene (iPP) MPs exhibited higher adsorption capacity to triclosan (TCS) than pristine ones, and the sorption affinity was enhanced with the increase of ionic concentrations. The crucial influence of cations on the adsorption behavior of aged MPs mainly depended on the changed properties of TCS and interactions between MPs and TCS. Salting out effect induced the precipitation of TCS from water and facilitated the partition of TCS onto MPs in high salinity water. Besides, compressing electrostatic double layer of MPs via squeezing out effect and bridging effect between functional groups of aged MPs and contaminants may also be significant factors in the sorption process. These findings will be helpful for understanding the role of cations on the transport of pollutants, the fate of MPs and their associated environmental risks in aquatic ecosystems.

Optical properties and theoretical study of Mn doped ZnAl2O4 nanoparticles with spinel structure

Zn1-xMnxAl2O4 (x = 0, 0.10, 0.20, 0.30 and 0.40) nanoparticles were synthesized by hydrothermal method, and the effects of Mn doping on the microstructure, morphology, binding energy and optical property of the samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), x-ray photoemission spectroscopy (XPS), ultraviolet–visible (UV–Vis) spectroscopy, photoluminescence spectra (PL) and fourier transform infrared spectroscopy (FT-IR). And the energy band structure of various defects in ZnAl2O4 structure were calculated by means of the first-principles calculations. The experimental results show that Zn1-xMnxAl2O4 nanoparticles possess cubic spinel structure without other impurity phases. The morphology of the samples exhibits irregular spherical or ellipsoid particles with uniform particle size. EDX Mapping display that Zn, Al, O and Mn elements are uniformly distributed without any enrichment phenomenon throughout the sample. Mn ions successfully used as doping agent replaced Zn2+ and entered ZnAl2O4 matrix. Combined with the calculated results of the first principle calculations, the substitution of Mn introduced new energy levels, which level make the intensity of PL spectra decrease and occur quenching phenomenon. XPS spectra demonstrate that the doped Mn ions mainly occupy the tetrahedral sites. UV–vis spectra indicate with the increase of Mn ion concentration, the band gap of the doped sample decrease with the increase of Mn content and exhibit red shift. FT-IR show that all Mn2+ ions substituted for Zn2+ ions without changing ZnAl2O4 spinel structure.

Enhancement of Electrical and Optical Properties of Sodium Bromide Doped Carboxymethyl Cellulose Biopolymer Electrolyte Films

Biodegradable ion conducting solid polymer electrolyte films of carboxymethyl cellulose (CMC) doped with sodium bromide (NaBr) with various weight percentages were prepared by a solution casting technique. Their structural, optical and electrical properties were studied by various experimental techniques in order to understand the impact of the sodium metal salt on the biopolymer CMC’s properties. The optical parameters namely the optical bandgap energy and the refractive index, showed a significant variable variation with the metal salt concentration. The maximum dc conductivity was found to be ∼5.15 × 10−4 S cm−1 at room temperature for the sample with 20 wt% of NaBr content in the CMC matrix. The ionic conductivity and dielectric constant in general, increased with increase in metal salt content, affirming the increase in ion concentration. The calculated transference number showed that the conductivity was mainly due to ions. The increase in conductivity was due to an increase in degree of amorphousness of the polymer upon doping, as analyzed by their XRD spectra.

Effects of lead ions on germination, initial growth, and physiological characteristics of Lolium perenne L. species and its bioaccumulation potential.

The present study was conducted to investigate the responses of Lolium perenne L. species to lead ions. To do this, the effects of lead ions at five levels: control (blank), 250, 500, 750, and 1000 mg/kg or mg/L (depending on germination in the soil or petri dish) on the germination, initial growth, and physiological characteristics of Lolium perenne were investigated. The results showed that the difference between various lead concentrations was statistically significant at 1% confidence level in all of the germination, vegetative, and physiological characteristics. In addition, the results of translocation and stress factors indicated that there was a significant difference between the control treatment and the concentrations of 250, 500, 750, and 1000 mg/L of lead ions. Results show that the mean value of stress, which was 0.3196 in the control value, reached 0.4154 at the concentrations 1000 mg/L. Different levels of lead ions had significant effect on the estimated characteristics including germination percentage, seed vigor, germination index, chlorophyll a, chlorophyll b, carotenoids, root, and shoot. The average germination percentage in the control was 46.66%, which decreased by 5% at the highest lead concentration. In addition, the average of seed vigor, which was 34.06 in the control conditions, decreased to 0.72 at the highest lead concentration. Also, the chlorophyll a dropped from 0.5261 mg/g in the control conditions to 0.3149 mg/g. On the other hand, increase in lead ion concentration affected the physiological characteristics of Lolium perenne species. Results suggest that Lolium perenne is capable of accumulating lead and is well tolerant to lead in soil. Therefore, it is concluded that it can be used for sowing on lands which are polluted to this heavy metal (up to the concentration of 1000 mg/kg).

Synthesis of multi-functionalized Fe3O4-NH2-SH nanofiber based on chitosan for single and simultaneous adsorption of Pb(II) and Ni(II) from aqueous system

A multi-functionalized poly ether sulfone (PES)/ chitosan (CS)/Fe3O4-NH2-SH nanofiber was applied for single and simultaneous removal of Pb(II) and Ni(II) ions from water systems. The structure of nanofibers was evaluated using FTIR, FESEM, BET, BJH, TGA, EDX and XPS analyses. The characterization results showed that the structure of nanofibers was well maintained after adsorption process. The simultaneous effects of solution pH, adsorbent dosage and Fe3O4-NH2-SH content were studied using response surface methodology (RSM). The predicted optimum conditions were identified for both Pb(II) and Ni(II) ions. Furthermore, the influence of contact time, initial ion concentration and temperature were investigated to evaluate the adsorption kinetics, isotherms and thermodynamics, respectively. Kinetic data fitted well to the double-exponential model for both Pb(II) and Ni(II) ions. Also, the results of isotherm investigation showed that a monolayer adsorption onto the PES/CS/Fe3O4-NH2-SH nanofiber was dominant. The maximum adsorption capacity of CS/PES/Fe3O4-NH2-SH was 282.4 mg/g for Pb(II) ions and 95.3 mg/g for Ni(II) ions. The regeneration test of nanofiber adsorbent displayed that the adsorption capacity did not changed significantly after 4 desorption steps. In binary system, the adsorption capacity decreased with the increase of competitive ion concentration. The selectivity of different metal ions followed the order of Pb(II) > Cu(II) > Ni(II) > Co(II) > Zn(II).

Application of PVDF-[BMIM][PF6] blends as the active material in screen-printed interdigital capacitors for temperature sensing

This work shows a method to fabricate interdigital capacitors having tunable sensitivity to temperature and stable behavior pointing to the application of ionic liquids (ILs) as fundamental building blocks in capacitive devices for temperature sensing in proximity conditions. Polyvinylidene fluoride (PVDF) in blend with 1-Butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) has been deposited by drop-casting from a N,N-dimethylformamide solution to be utilized as dielectric material in screen-printed interdigitated capacitors. Capacitance and conductance trends versus temperature have been analyzed and compared to bare PVDF dielectrics. The inclusion of [BMIM][PF6] in PVDF-IL blends increases the AC capacitance of the device and its sensitivity to the temperature in the examined range (+20 °C to +110 °C). AC measurements performed at 100 kHz have shown good electrical stability for PVDF-IL blends also when measured in ambient atmosphere. As a drawback, an increase in [BMIM][PF6] concentration resulted also in an increase in AC conductance which exhibits an Arrhenius activation with temperature. Such behavior has been attributed to the increase in ion concentration and ionic mobility with temperature. The work also shows the presence of a limit value for the activation energy of AC conductance for higher concentrations of the ionic liquid.

Colloidal biliquid aphron demulsification using polyaluminum chloride and density modification of DNAPLs: optimal conditions and common ion effect.

Dense non-aqueous phase liquids (DNAPLs) entrapped and pooled in aquifers serve as a long term source of groundwater contamination because of their low solubility and high density. Density modification displacement (DMD) with colloidal biliquid aphrons (CBLAs) is a promising approach to prevent DNAPL downward migration during surfactant-based remediation processes. CBLA demulsification and quick release of internal light organic matter is the key to density modification of DNAPLs. In this work, it is reported for the first time that polyaluminum chloride (PAC) could destabilize CBLAs efficiently. The optimum conditions for demulsification of CBLAs by PAC were obtained; the effects of several specific ions in groundwater on demulsification of CBLAs by PAC were investigated. The results indicated that the CBLA was completely demulsified by PAC within 10 minutes and released light organic matter. It recorded the highest demulsification efficiency when the addition ratio (VPAC/VCBLA) was 2 : 1, concentration of PAC was 0.7 g L-1 and the PVR of CBLAs was 8. Most cations (sodium, magnesium and calcium ions) had inhibitory effects on demulsification of CBLAs by PAC with increasing ion concentration, but iron ions had no effect on it. Sulfate anions showed a stronger inhibitory effect on demulsification of CBLAs by PAC compared to chloride ions. With PAC as the demulsifier, CBLAs could be demulsified efficiently, irreversibly modifying the density of trichloroethylene in 5 minutes.

Optical properties of Cr doped ZnAl2O4 nanoparticles with Spinel structure synthesized by hydrothermal method

Zn1−xCrxAl2O4 (x = 0, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by hydrothermal method and heat treatment technology, and the effects of Chromium doping ratios on the microstructure, morphology, element distribution, binding energy and optical property of the samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray energy dispersive spectroscopy (XEDS), x-ray photoemission spectroscopy (XPS), ultraviolet-visible (UV–vis) spectroscopy, photoluminescence spectra (PL) and fourier transform infrared spectroscopy (FT-IR). The experimental results show that Zn1−xCrxAl2O4 nanoparticles possess cubic spinel structure without other impurity phases. The average crystallite size decrease and the lattice parameter increase with the increase of Cr doping concentration. The morphology of the samples exhibits irregular spherical or ellipsoid particles with uniform particle size. XEDS spectra display Cr3+ successfully used as doping agent replaced Zn2+ and entered ZnAl2O4 matrix. XPS spectra demonstrate that the doped Cr ions mainly occupy the tetrahedral sites in Zn0.95Cr0.05Al2O4 sample. UV–vis spectra indicate the band gap of the doped sample decrease and exhibit red shift with the increase of Cr ion concentration. The intensity of FT-IR spectra for Zn1−xCrxAl2O4 samples decreases slowly and occurs red shift. PL spectra show the intensity decrease and occur luminescence quenching phenomenon for Cr doped sample.

Tunable plasmonics of hollow raspberry-like nanogold for the robust Raman scattering detection of antibiotics on a portable Raman spectrometer.

It is important to develop novel sensors for the simple, rapid, and quantitative detection of residual antibiotics in food, considering their potential threats to human health. Herein, we report the successful fabrication of raspberry-like nanogold (R-like Au) structures with rough surfaces and partially hollow structures for the rapid and sensitive detection of antibiotics in duck meats on a portable Raman spectrometer. The R-like Au with tunable plasmonic wavelengths was fabricated by a two-step method. Ag particles as seeds were substituted by Au particles through a replacement reaction; moreover, the surface plasmon resonances (SPRs) of R-like Au red-shifted with the increase in the Au ion concentration. The R-like Au with a diameter of about 120 nm that matched well with the 785 nm laser on the portable Raman spectrometer was used as an excellent surface-enhanced Raman spectroscopy (SERS) active platform for detecting two kinds of antibiotics, namely, nitrofurantoin (NFT) and nitrofurazone (NFZ), in spiked duck meats. Both of them have sufficient sensitivity (0.05-10 mg L-1), good linear relationship (R2 > 0.99) and high recovery in quantitative SERS analysis. The platform is simple without the need for complex pretreatment of the food samples or use of large scale Raman spectrometers, promising easy implementation for the on-site analysis of residuals of antibiotics in food.

Liquid-liquid extraction of Co(II) from nitrate solution using TOA

Cobalt has widespread industrial applications but if present in excess amounts it may cause several noxious effects. Liquid-liquid extraction process can be useful in cleaning the environment from harmful chemical pollutants. Solvent extraction of cobalt using cobalt nitrate as the feed solution and trioctylamine (TOA) as the extractant in toluene was carried out where the effects of nitric acid concentration, equilibration time, concentration of the extractant and cobalt ions had been investigated. The percentage extraction of Co(II) decreased upon increasing the concentration of acid. A time of 15 min was needed to achieve the extraction equilibrium. Highest percentage extraction of cobalt was achieved using 0.1 M TOA which is 99%. Cobalt loading increased with increase in metal ion concentration. Presence of nitrate ions had almost no significance in the extraction process. The loaded organic phase was stripped using different stripping agents and 99.15% back extraction was achieved with 0.1 mol/L (NH4)2CO3. The extraction mechanism was proposed from the FTIR and slope measurement.

Adsorption of Lead (II) and Copper (II) Ions from Mono Synthetic Aqueous Solutions Using Bio-Char from <i>Ficus natalensis</i> Fruits

Many science-based institutions in most developing countries use heavy metal containing salts in practical teaching sessions. The commonly used chemicals are the salts of lead (II) and copper (II) and the wastes generated end up into the environment when untreated. Thus, a study was done to remove lead (II) and copper (II) ions from mono synthetic aqueous solution using bio-char from Ficus natalensis fruits (FNF). This was done at varied pH, contact time, temperature, bio-char dosage level, salinity and metal ion concentration using the batch approach. The residual metal concentrations were determined using the atomic absorption spectrophotometer. The optimum pH for the adsorption of copper (II) and lead (II) ions was found to be 4.0 and 5.0 respectively. The maximum percentage adsorption of copper (II) and lead (II) by the FNF bio-char was established at 60 minutes contact time, 47.5&degC and 0.4 g adsorbent dose. Increase in the metal ion concentration and the presence of interfering ions in the aqueous solution lead to decrease in the percentage adsorption. The highest adsorption capacity was found to be 161.29 mg/g and 1250 mg/g for copper (II) and lead (II) ions respectively. The thermodynamic parameters indicated the feasibility of the adsorption of copper (II) and lead (II) on the bio-char of FNF. Thus, bio-char from FNF may be used as an adsorbent in waste management where copper (II) and lead (II) ions are present at a concentration range of between 5 and 100 mg/l.

Sorption properties of polymeric beads and films containing tetraoctyl diglycolamide towards europium (III) ions

The article presents results obtained during investigation of Eu(III) ion removal from aqueous solutions using triacetate cellulose films and styrene-divinylbenzene copolymer beads containing tetraoctyl diglycolamide (TODGA). A simple method for manufacturing films containing up to 50 % w/w TODGA is provided. Solution acidity effect on the removal rate of Eu(III) ions was studied. Maximum removal of Eu(III) ions was obtained in nitric acid solutions with concentrations of 1-6 mol/l. Additionally, increase in the europium removal rate is also observed at pH > 2 for beads and in the pH range of 2 to 4 for films. In the former case increase in the removal rate is explained by increase in the nitrate ion concentration in the solution and Eu(NO3)3(TODGA)3 complex formation, and in the latter case – by decrease in TODGA protonation rate with рН growth. Observed trends indicate a high similarity in surface sorption mechanisms between the materials studied. Sorption equilibrium of Eu(III) ions onto the styrene-divinylbenzene copolymer beads impregnated with TODGA is adequately fitted to Langmuir sorption isotherm. The maximum sorption capacity of this material for Eu(III) removal from solutions with nitric acid concentration of 1 mol/l is 7.4 mg/g. It has been found that the maximum removal rate of Eu(III) ions by the triacetate cellulose films is achieved for TODGA content in the films ≥ 40 % w/w. The possibility of selective europium sorption from natural water using both beads and films is shown. Although cations present in natural water do not bind to sorbents studied, there is still slight deterioration in sorption properties when moving from model solutions to natural water. Complete desorption of Eu(III) ions from the film surface is achieved by washing three times with an EDTA solution, рН = 6.8. Prepared films can be reused for Eu(III) ion removal.

Fretting manifestations in total hip prosthesis

This paper analyses the fretting and fretting wear phenomena to the classical and modular hip prostheses. Theoretical and experimental manifestations are studied, at the interface of the femoral stem with the bone cement mantle, at the taper junction between the femoral stem and the femoral head of the prosthesis, as well as at the tapering of the femoral neck adapter’s connections with the stem and the femoral head. The aim of the paper is to highlight the modularization implications of the femoral component of the Total Hip Prosthesis, especially its tribological implications (fretting wear of modular junctions, fatigue and corrosion by fretting) which can contribute to wear and increasing ion concentrations of the metal in the blood, and the possibility of the femoral shaft fracture at the femoral head junction. Theoretical approach described, allows the “Archard” law implementation to predict the fretting wear. Experimental laboratory studies focused on the analysis of the tribological phenomena occurring at the taper junctions between the femoral head and neck, as well as the neck and femoral stem, highlighting the relevant qualitative tribological aspects. For this purpose, experimental junctions were fabricated and tested on a universal MTS mechanical machine, equipped with a fatigue testing device.

Complementary responses of stream fish and benthic macroinvertebrate assemblages to environmental drivers in a shale-gas development area

Shale-gas production could impact freshwater quality through contamination of the physical and chemical habitat (e.g., fracturing fluids, untreated or treated effluent) or development-related impacts. Despite environmental concerns, information is lacking to support biomonitoring as a diagnostic tool to assess impacts of shale-gas production. We characterized water quality and biota in areas of high shale gas potential (Early Carboniferous bedrock in New Brunswick, Canada) and surrounding geologic areas, and we assessed patterns in benthic macroinvertebrate (BMI) and fish assemblages. Early Carboniferous stations differed primarily based on water chemistry, and BMI were associated with a gradient in conductivity and temperature across geologic classes. Concordance analysis indicated similar classification of stations by both organism groups, though fish were more related to turbidity and nutrients. Concordance among fish and BMI was strongest at high conductivity, Early Carboniferous stations. These results suggest that geology plays a strong role in driving abiotic habitats and biotic communities of streams, even at small spatial scales. Furthermore, they suggest BMI and fish can provide complementary information for biomonitoring in shale-gas development areas, with BMI responding to increased ion concentrations from surface water contamination, and fish responding to changes in nutrients and turbidity resulting from development.

An Electrically Actuated, Carbon-Nanotube-Based Biomimetic Ion Pump.

Single-walled carbon nanotubes (SWCNTs) are well-established transporters of electronic current, electrolyte, and ions. In this work, we demonstrate an electrically actuated biomimetic ion pump by combining these electronic and nanofluidic transport capabilities within an individual SWCNT device. Ion pumping is driven by a solid-state electronic input, as Coulomb drag coupling transduces electrical energy from solid-state charge along the SWCNT shell to electrolyte inside the SWCNT core. Short-circuit ionic currents, measured without an electrolyte potential difference, exceed 1 nA and scale larger with increasing ion concentrations through 1 M, demonstrating applicability under physiological (∼140 mM) and saltwater (∼600 mM) conditions. The interlayer coupling allows ionic currents to be tuned with the source-drain potential difference and electronic currents to be tuned with the electrolyte potential difference. This combined electronic-nanofluidic SWCNT device presents intriguing applications as a biomimetic ion pump or component of an artificial membrane.