Polyaniline fibres as electrodes.: Electrochemical characterisation in acid solutions

Polyaniline fibre microelectrodes prepared from a doped solution of polyaniline protonated with 2-acrylamido-2-methyl-1-propanesulphonic acid in dichloracetic acid were characterized electrochemically for the first time. Low scan rate cyclic voltammetry was used for characterisation in different acid electrolyte solutions, hydrochloric, nitric, perchloric, sulphuric and phosphoric, at low pH values with varying positive potential limits. Electrochemical impedance spectroscopy was also utilised. The electrochemical behaviour of polyaniline (PANI) fibres was found to be similar to that of PANI films obtained by electropolymerisation on metallic electrode substrates. The conduction potential window was found to be from +0.20 to +0.60 V versus SCE, with small variations in the different acid solutions as well as with pH. The standard electrochemical redox couple hexacyanoferrate(III), was found to behave quasi-reversibly in the conduction potential region and rate constants were evaluated.     

Electrochemical impedance studies of chitosan-modified electrodes for application in electrochemical sensors and biosensors

Graphite-epoxy resin composite (GrEC) electrodes were modified with chitosan (Chit) films and characterised using electrochemical impedance spectroscopy (EIS). Several film modifications were made using different crosslinking agents: glutaraldehyde (GA), glyoxal (GO), epichlorohydrin (ECH) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) together with N-hydroxysuccinimide (NHS) and the characteristics of each of them evaluated in the presence of model electroactive compounds potassium hexacyanoferrate(III) and hexaammineruthenium(III) chloride. Immobilisation of functionalised carbon nanotubes into chitosan matrices (Chit-CNT) using the same crosslinking agents was also investigated. The impedance of the electrode with the best performance (GrEC/Chit-CNT/EDC-NHS) was characterised as a sensor for dipyrone and hydroquinone and for a glucose biosensor by immobilisation of glucose oxidase (GOx) on top of Chit-CNT using GA. Modelling and equivalent circuit analysis was carried out, with emphasis on diffusion characteristics and the significant features of the spectra are discussed.     

ICT implementation in the health-care sector: effective stakeholders’ engagement as the main precondition of change sustainability

As modern information and communication technologies (ICT) now offer new possibilities for improving almost every aspect of health care, their implementation is a very relevant and fast accelerating process around Europe and internationally. The processes themselves vary greatly from scattered single initiatives of various IT solutions to large national programmes. Often treated as purely technical in nature, ICT implementation in health care should gravitate towards the “softer/complex” i.e. people-related issues end of the change. The approach taken by the Informing Healthcare programme in Wales broadens understanding on the value that engagement of stakeholders can bring to the process.

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Electrochemical, EIS and AFM characterisation of biosensors: Trioxysilane sol-gel encapsulated glucose oxidase with two different redox mediators

Sol-gel encapsulated glucose oxidase (GOx) enzyme electrodes based on carbon film resistors with chemically deposited copper hexacyanoferrate (CuHCF) or poly(neutral red) (PNR), made by electrochemical polymerisation, as redox mediator have been developed and characterised using cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy. The sol-gel was prepared using three different trioxysilanes: 3-aminopropyl-triethoxysilane (APTOS), 3-glycidoxypropyl-trimethoxysilane (GOPMOS) and methyltrimethoxysilane (MTMOS), without alcohol addition, and alcohol formed during the hydrolysis of the precursor compounds was removed. The best sensitivity, ∼60 nA mM⁻¹, for glucose and limit of detection (2-40 μM, depending on the sol-gel precursor) were obtained when PNR was used as a mediator, but the linear range (50-600 μM) was two to four times lower than that at CuHCF mediated biosensors, using an operating potential of +0.05 V at CuHCF or −0.25 V versus saturated calomel electrode (SCE) at PNR mediated electrodes. The stability of the sensor depended on the sol-gel morphology and was 2 months testing the biosensor every day, while the storability was at least 4 months in the case of GOPMOS, the sensors being kept in buffer at +4 °C.     

Chitosan–Alginate Microcapsules Provide Gastric Protection and Intestinal Release of ICAM‐1‐Targeting Nanocarriers,Enabling GI Targeting In Vivo

When administered intravenously, active targeting of drug nanocarriers (NCs) improves biodistribution and endocytosis. Targeting may also improve NC oral delivery to treat gastrointestinal (GI) pathologies or for systemic absorption. However, GI instability of targeting moieties compromises this strategy. This study explores whether encapsulation of antibody‐coated NCs in microcapsules would protect against gastric degradation, providing NC release and targeting in intestinal conditions. Nanoparticles coated with antibodies against intercellular adhesion molecule‐1 (anti‐ICAM) or nonspecific immunoglobulin G (IgG) are encapsulated in chitosan (shell) ‐ alginate (core) microcapsules. Encapsulation efficiency is >95% and NC relase from microcapsules in storage is <10%. There is minimal NC release at gastric pH (<10%) and burst release at intestinal pH (75%–85%). Encapsulated NCs afford increased protection against degradation (threefold to fourfold) and increased cell targeting (8–20‐fold) after release versus the nonencapsulated NCs. Mouse oral gavage shows that microencapsulation provides 38%–65% greater protection of anti‐ICAM NCs in the GI tract, 40% lower gastric retention, and fourfold to ninefold enhanced intestinal biodistribution versus nonencapsulated NCs. Therefore, microencapsulation of antibody‐targeted NCs may enable active targeting strategies to be effective in the context of oral drug delivery.     

Development of Integrated Capacitance Resistive Model for predicting waterflood performance: a study on formation damage

The Integrated Capacitance Resistive Model (ICRM), a linearized form of Capacitance Resistive Models (CRM), has been commonly used to match liquid production history and estimate interwell connectivity (IWC) in waterflooded reservoirs. Although this model fits cumulative production data accurately, it usually fails to estimate correct values of total production, where backward subtraction of cumulative production delivers highly overestimated or underestimated total production rates. To address this issue, a modified optimization approach is presented to minimize the error between both cumulative and total production data through two consecutive constrained objective functions. This paper validates the modified ICRM in homogeneous synthetic examples with vertical wells to show how the new approach can successfully characterize the waterflooded reservoirs. The model was also tested in damaged formations to detect its impact on the communication between wells. Finally, a correlation is proposed to explain the mathematical and physical relationship between formation damage (skin factor) and IWC of the damaged well.

Abbreviations BHP: bottom-hole pressure; CMG: computer modeling group Ltd.; COF: Consecutive objective function; CRM: capacitance-resistive model or capacitance-resistance model; CWI: cumulative water injection; ICRM: integrated capacitance-resistance model; IMEX: Implicit-explicit black oil simulator     

Effects of polyglycolic acid and polypropylene meshes on postoperative adhesion formation in mice

The purpose of this study was to investigate the effects of polyglycolic acid (PGA), an absorbable (ABS) mesh, and polypropylene (PP), a nonabsorbable (NA) mesh, on intestinal adhesion formation. Altogether 72 mice were divided into a control group of 24, an ABS mesh group of 23, and an NA mesh group of 25. All three groups were divided into two subgroups for evaluation of adhesion severity at postoperative (po) days 5 and 90. Adhesion severity was measured with adhesion grading and tissue hydroxyproline (OHP) levels. Adhesion degree was minimal (1) in all subjects on day 5. Also there was no difference in tissue OHP levels between three groups on day 5 (p > 0.05). Adhesion degree and tissue OHP levels as determinants of adhesion severity were higher in the PGA mesh group than the control group and the PP mesh group on day 90 (p < 0.001). There was no difference between the control group and the PP mesh groups (p > 0.05). Adhesion degree was higher on day 90 than on day 5 in the control group and the PGA mesh group (p < 0.05), whereas tissue OHP level was higher on day 90 than on day 5 in all three groups (p < 0.001). Also there was linear correlation between adhesion degree and tissue OHP levels (r = 0.86, p < 0.001). The study demonstrates that ABS PGA mesh has higher potential for adhesion formation than the NA PP mesh, probably related to the increased foreign body and inflammatory reactions during the absorption process of the mesh.     

Peculiarities of Starch Cationization with Glycidyltrimethylammonium Chloride

Cationic starch derivatives containing quaternary ammonium groups with high degree of substitution are prepared by reaction of starch with glycidyltrimethylammonium chloride (GTAC) in different reaction media. In aqueous solutions of GTAC along with conventional hydrolysis of epoxy groups, their interaction with chloride ions also takes place. This resulted in formation of hydroxyl ions which accelerate both the hydrolysis of GTAC epoxy groups and can act as the internal catalyst in the reaction of GTAC with starch. Therefore, even in the absence of the external catalyst, cationic starch with a high degree of substitution can be obtained. The autocatalytic reaction of GTAC with starch proceeds more rapidly at higher temperatures but with lower reaction efficiency. Both in the absence of the external catalyst and in the case when sodium alkali is used as a catalyst the reaction of starch with GTAC proceeds only when a particular quantity of “free” water is present in the system. When the NaOH as catalyst is used the reaction efficiency is about 90%. The yield of starch cationization reaction decreases when the quantity of “free” water is twice or thrice higher than required for starch modification to begin.     

Urine Molecular Biomarkers for Detection and Follow-Up of Small Renal Masses

Active surveillance (AS) is the best strategy for small renal masses (SRMs) management; however, reliable methods for early detection and disease aggressiveness prediction are urgently needed. The aim of the present study was to validate DNA methylation biomarkers for non-invasive SRM detection and prognosis. The levels of methylated genes TFAP2B, TAC1, PCDH8, ZNF677, FLRT2, and FBN2 were evaluated in 165 serial urine samples prospectively collected from 39 patients diagnosed with SRM, specifically renal cell carcinoma (RCC), before and during the AS via quantitative methylation-specific polymerase chain reaction. Voided urine samples from 92 asymptomatic volunteers were used as the control. Significantly higher methylated TFAP2B, TAC1, PCDH8, ZNF677, and FLRT2 levels and/or frequencies were detected in SRM patients’ urine samples as compared to the control. The highest diagnostic power (AUC = 0.74) was observed for the four biomarkers panel with 92% sensitivity and 52% specificity. Methylated PCDH8 level positively correlated with SRM size at diagnosis, while TFAP2B had the opposite effect and was related to SRM progression. To sum up, SRMs contribute significantly to the amount of methylated DNA detectable in urine, which might be used for very early RCC detection. Moreover, PCDH8 and TFAP2B methylation have the potential to be prognostic biomarkers for SRMs.