Binary and Ternary Deep Eutectic Solvents for Methylene Green Electropolymerization on Multiwalled Carbon Nanotubes: Optimization, Characterization and Application.

Choline chloride (ChCl) based binary and ternary deep eutectic solvents (DES) were evaluated for methylene green electropolymerization with oxalic acid (OA) and ethylene glycol (EG) as hydrogen bond donors. Binary DES ChCl:OA in molar ratios 1:1 and 2:1 and ChCl:EG 1:2 and ternary DES (tDES) in different molar ratios and percentages of water were evaluated. The highest polymer growth was in ChCl:OA:EG-tDES with added water, that had a lower viscosity and higher ionic conductivity when associated with HCl as dopant. This enhanced the formation of more cation radicals and, consequently, more polymer formation. The PMG/MWCNT/GCE-tDES sensor was successfully applied to the simultaneous determination of 5-aminosalicylic acid (5-ASA) and acetaminophen (APAP) by differential pulse voltammetry in the concentration range 2 µM - 200 µM, with detection limits of 0.37 µM and 0.49 µM for 5-ASA and APAP, respectively. The sensor demonstrated good repeatability, reproducibility and stability, and was successfully applied in pharmaceutical formulations.

No Difference in Revision Rates or Patient-Reported Outcome Measures Between Surgical Approaches for Total Hip Arthroplasty Performed for Femoral Neck Fracture: An Analysis of 5,025 Primary Total Hip Arthroplasties From the New Zealand Joint Registry.

BACKGROUND: Total hip arthroplasty (THA) for femoral neck fracture (FNF) can be performed through different surgical approaches. This study compared the revision rates and patient-reported outcome measures by surgical approach. METHODS: Data from the New Zealand Joint Registry were analyzed for patients undergoing primary THA for FNF from January 2000 to December 2021. A total of 5,025 THAs were performed for FNF; the lateral approach was used in 2,499 (49.7%), the posterior in 2,255 (44.9%), and the anterior in 271 (4.3%). The primary outcome measure was the all-cause revision rate. Secondary outcome measures included revision rates for: dislocation, aseptic femoral component loosening, periprosthetic fracture, and infection. Oxford Hip Scores (OHS) were also collected. Age, sex, body mass index, American Society of Anesthesiologists score, femoral head size, dual mobility use, femoral fixation, and surgeon experience were assessed as potential confounding variables. RESULTS: There was no difference in the revision rates between lateral and posterior (P = .156), lateral and anterior (P = .680), or posterior and anterior (P = .714) approaches. There was no difference in the reasons for revision between the lateral and posterior approaches or 6-month OHS (P = .712). There was insufficient data to compare the anterior approach. CONCLUSIONS: There is no difference in the overall revision rates, reasons for revision, or OHS between the lateral and posterior surgical approaches for THA performed for FNF. Insufficient data on the anterior approach is available for an accurate comparison. LEVEL OF EVIDENCE: Level III.

The effect of age on emotion processing in individuals with mood disorders and in healthy individuals.

Introduction: Emotion processing is an essential part of interpersonal relationships and social interactions. Changes in emotion processing have been found in both mood disorders and in aging, however, the interaction between such factors has yet to be examined in detail. This is of interest due to the contrary nature of the changes observed in existing research - a negativity bias in mood disorders versus a positivity effect with aging. It is also unclear how changes in non-emotional cognitive function with aging and in mood disorders, interact with these biases. Methods and results: In individuals with mood disorders and in healthy control participants, we examined emotional processing and its relationship to age in detail. Data sets from two studies examining facial expression recognition were pooled. In one study, 98 currently depressed individuals (either unipolar or bipolar) were compared with 61 healthy control participants, and in the other, 100 people with bipolar disorder (in various mood states) were tested on the same facial expression recognition task. Repeated measures analysis of variance was used to examine the effects of age and mood disorder diagnosis alongside interactions between individual emotion, age, and mood disorder diagnosis. A positivity effect was associated with increasing age which was evident irrespective of the presence of mood disorder or current mood episode. Discussion: Results suggest a positivity effect occurring at a relatively early age but with no evidence of a bias toward negative emotions in mood disorder or specifically, in depressed episodes. The positivity effect in emotional processing in aging appears to occur even within people with mood disorders. Further research is needed to understand how this fits with negative biases seen in previous studies in mood disorders.

Designing and validating a research questionnaire - Part 2.

Validity and reliability refer to the accuracy and consistency of a research tool. In the previous article in this series, we examined the development of a research questionnaire. In this article, we discuss the methods of determining the validity and reliability of a research questionnaire.

Modeled underwater sound levels in the Pan-Arctic due to increased shipping: Analysis from 2013 to 2019.

The loss of Arctic sea ice is one of the most visible signs of global climate change. As Arctic sea ice has retreated, Arctic marine shipping has increased. The Pan-Arctic's unique underwater acoustic properties mean that even small increases in ship traffic can have a significant effect on the ambient soundscape. This study presents the first long-term, basin-scale model of shipping noise in the Pan-Arctic with a focus on a few select sub-regions. The Arctic Ship Traffic Database from the Protection of the Arctic Marine Environment is used in this study to model the locations and source levels from ships operating in the Pan-Arctic between 2013 and 2019. The acoustic footprint of these ships is explored temporally for the entire basin as well as for the select large maritime ecosystems of the Barents Sea, the Northern Bering-Chukchi Sea, and Baffin Bay. From 2013 to 2019, modeled shipping noise propagating underwater broadly increased between 5-20 dB across the Pan-Arctic, but more specific results in sub-regions are presented and discussed.

Effect of surgeon-specific feedback on surgical outcomes: a systematic review of the literature.

BACKGROUND: Surgeon-specific outcome reporting provides an opportunity for quality assurance and improved surgical results. It is becoming increasingly prevalent and remains contentious amongst surgeons. The purpose of this systematic review was to evaluate the extent to which published literature supports the concept that feedback of surgeon-level outcomes reduces morbidity and/or mortality. No systematic reviews have previously been completed on this subject. METHODS: Medline and Embase were systematically searched for studies published prior to the 1st of January 2022. Feedback was defined as a summary of clinical performance over a specified period of time provided in written, electronic or verbal format. Studies were required to provide surgeon-specific feedback to multiple individual consultant surgeons with the primary purpose being to determine if feedback improved outcomes. Primary outcome(s) needed to relate to surgical outcomes as opposed to process measures only. All surgical specialties and procedures were eligible for inclusion. RESULTS: Seventeen studies were included in the review, traversing a wide range of specialties and procedures. Sixteen were non-randominsed and one randomized. Fifteen were before and after studies. The balance of the non-randomized studies support the concept that provision of surgeon-specific feedback can improve surgical outcomes, while the single randomized study suggests feedback may not be effective. CONCLUSIONS: This systematic review supports the use of surgeon-level feedback to improve outcomes. The strength of this finding is limited by reliance on before and after studies, further randomized studies on this subject would be insightful.

A Facile Synthesis Route to AuPd Alloys for the Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid.

Synthesis of 2,5-furandicarboxylic acid (FDCA) can be achieved via catalytic oxidation of 5-hydroxymethylfurfural (5-HMF), in which both base and catalyst play important roles. This work presents the development of a simple synthesis method (based on a commercial parent 10 wt.% Pd/C catalyst) to prepare the bimetallic AuPd alloy catalysts (i. e., AuPd/C) for selective 5-HMF oxidation to FDCA. When using the strong base of NaOH, Pd and Au cooperate to promote FDCA formation when deployed either separately (as a physical mixture of the monometallic Au/C and Pd/C catalysts) or ideally alloyed (AuPd/C), with complete 5-HMF conversion and FDCA yields of 66 % vs 77 %, respectively. However, NaOH also promoted the formation of undesired by-products, leading to poor mass balances (<81 %). Comparatively, under weak base conditions (using NaHCO3 ), an increase in Au loading in the AuPd/C catalysts enhances 5-HMF conversion and FDCA productivity (due to the enhanced carbonyl oxidation capacity) which coincides with a superior mass balances of >97 %. Yet, the excessive Pd content in the AuPd/C catalysts was not beneficial in promoting FDCA formation.

Rheumatoid interstitial lung disease in Canterbury, Aotearoa New Zealand - A retrospective cohort study.

BACKGROUND: Rheumatoid arthritis associated interstitial lung disease (RA-ILD), is an important extra-articular manifestation of rheumatoid arthritis (RA). The frequency, risk factors, and prognosis of RA-ILD are incompletely understood. AIMS: To determine the prevalence and incidence, clinical characteristics and risk factors for development, and outcomes of persons with RA-ILD in the population of the Canterbury District Health Board (CDHB) catchment area. METHODS: Individuals aged ≥ 18 years with RA, resident in the CDHB catchment area between 1 January 2006 and 31 December 2008 (Period One), and 1 January 2011 to 31 December 2013 (Period Two) were identified by medical record review and followed until 30 June 2019. Individuals with RA-ILD as defined by pre-specified criteria were identified. The association between demographic and clinical characteristics and RA-ILD development and mortality was examined using Cox-proportional hazards models. RESULTS: The prevalence of RA-ILD per 100,000 was 10.97 (95 % CI 7.53,14.42) for Period One, and 14.74 (95 % CI 10.84,18.63) for Period Two. Among individuals evaluated for risk factors for RA-ILD development, the estimated cumulative incidence of ILD at 10 years was 4.47 % (95 % CI 3.14, 6.14). After adjusting for age, rheumatoid factor positivity (HR 3.73, 95 % CI, 1.32,10.56), extra-articular manifestations other than RA-ILD (HR 4.48, 95 % CI 2.36,8.48), and subcutaneous rheumatoid nodules (HR 4.66, 95 % CI 2.34, 9.26) were associated with increased risk of developing RA-ILD. The standardised mortality ratio for RA-ILD was 3.90 (95 % CI 2.55,5.72) compared to the general population. Extent of ILD on CT chest was associated with mortality (HR for >20% vs. < 20 % 4.47, 95 % CI 1.67,11.96). CONCLUSIONS: Clinically evident RA-ILD occurred in approximately 5 % of individuals with RA. Mortality was increased almost fourfold compared to the general population. Radiologic extent was the most important prognostic factor.

Impact of Porous Silica Nanosphere Architectures on the Catalytic Performance of Supported Sulphonic Acid Sites for Fructose Dehydration to 5-Hydroxymethylfurfural.

5-hydroxymethylfurfural represents a key chemical in the drive towards a sustainable circular economy within the chemical industry. The final step in 5-hydroxymethylfurfural production is the acid catalysed dehydration of fructose, for which supported organoacids are excellent potential catalyst candidates. Here we report a range of solid acid catalysis based on sulphonic acid grafted onto different porous silica nanosphere architectures, as confirmed by TEM, N2 porosimetry, XPS and ATR-IR. All four catalysts display enhanced active site normalised activity and productivity, relative to alternative silica supported equivalent systems in the literature, with in-pore diffusion of both substrate and product key to both performance and humin formation pathway. An increase in-pore diffusion coefficient of 5-hydroxymethylfurfural within wormlike and stellate structures results in optimal productivity. In contrast, poor diffusion within a raspberry-like morphology decreases rates of 5-hydroxymethylfurfural production and increases its consumption within humin formation.

Fluorinated Mn(III)/(II)-Porphyrin with Redox-Responsive 1 H and 19 F Relaxation Properties.

A new fluorinated manganese porphyrin, (Mn-TPP-p-CF3 ) is reported capable of providing, based on the Mn(III)/Mn(II) equilibrium, dual 1 H relaxivity and 19 F NMR response to redox changes. The physical-chemical characterization of both redox states in DMSO-d6 /H2 O evidenced that the 1 H relaxometric and 19 F NMR properties are appropriate for differential redox MRI detection. The Mn(III)-F distance (dMn-F =9.7-10 Å), as assessed by DFT calculations, is well tailored to allow for adequate paramagnetic effect of Mn(III) on 19 F T1 and T2 relaxation times. Mn-TPP-p-CF3 has a reversible Mn(II)/Mn(III) redox potential of 0.574 V vs. NHE in deoxygenated aqueous HEPES/ THF solution. The reduction of Mn(III)-TPP-p-CF3 in the presence of ascorbic acid is slowly, but fully reversed in the presence of air oxygen, as monitored by UV-Vis spectrometry and 19 F NMR. The broad 1 H and 19 F NMR signals of Mn(III)-TPP-p-CF3 disappear in the presence of 1 equivalent ascorbate replaced by a shifted and broadened 19 F NMR signal from Mn(II)-TPP-p-CF3 . Phantom 19 F MR images in DMSO show a MRI signal intensity decrease upon reduction of Mn(III)-TPP-p-CF3 , retrieved upon complete reoxidation in air within ~24 h. 1 H NMRD curves of the Mn(III)/(II)-TPP-p-CF3 chelates in mixed DMSO/water solvent have the typical shape of Mn(II)/Mn(III) porphyrins.

Rising Kawasaki disease incidence in New Zealand: analysis of national population incidence and outcomes 2000-2017.

OBJECTIVE: The recent epidemiology of Kawasaki disease (KD) in New Zealand (NZ) is unknown. Our aim was to describe the incidence, seasonal variation, long-term outcomes and mortality for KD in NZ. DESIGN: Retrospective national database analysis. SETTING: New Zealand. PATIENTS: First hospitalisation and deaths diagnosed with KD. MAIN OUTCOME MEASURES: Data were extracted for all hospital admissions in NZ coded as KD (International Classification of Diseases (ICD)-9 and ICD-10) from the National Minimum Dataset 1 January 2000 to 31 December 2017. Age, sex, ethnicity and associated diagnoses were available to review. Intervention rates for immunoglobulin administration were also analysed. RESULTS: Over the study period, there were 1008 children with initial hospitalisation for KD. The mean age was 39.8 months (SD 37) and 592 (59%) were boys. The annual incidence rate of KD has increased from 12.2 to 19.5 per 100 000 children <5 years old (0.46 case increase per year; 95% CI 0.09 to 0.83). Children of Asian and Pacific Island ethnicities had the highest incidence (51.2 and 26.1/100 000, respectively). The highest growth in incidence was among East Asian children. The case mortality rate was low (12 of 1008, 1.2%); however, Maori were over-represented (6 of 12 deaths). CONCLUSIONS: There is evidence of increasing KD hospitalisation in NZ, similar to recent studies from Northeast Asia and Australia. KD incidence data were available for retrospective review from a national database, but data on complications and outcomes were incomplete. Notification for KD and an active national surveillance system are recommended to improve care. Future work should focus on factors contributing to poorer outcomes in Maori.

Incorporating faecal haemoglobin measurement using the faecal immunochemical test (FIT) in the referral, triage and prioritisation pathway for patients with colorectal symptoms.

Incorporating faecal haemoglobin (FHb) measurement using the faecal immunochemical test (FIT) in the investigation pathway for patients with colorectal symptoms may improve access to colonoscopy for those at greatest risk of significant disease. AIM: To derive a colorectal symptom pathway incorporating standard clinical and FIT data to guide referral, triage, and prioritisation of cases in New Zealand. METHOD: Diagnostic accuracy of FIT to rule out colorectal cancer (CRC) was determined by meta-analysis. Thereafter, the risk of CRC after FIT was estimated for common clinical presentations by Bayesian methodology, using a specifically collated retrospective cohort of symptomatic cases. A symptom/FIT pathway was developed iteratively following multi-disciplinary engagement. RESULTS: Eighteen studies were included in meta-analysis. The sensitivity and specificity for CRC were 89.0% (95%CI 87.0-90.9%) and 80.1% (95%CI 77.7-82.4%) respectively, at a FHb threshold of >10mcg haemoglobin per gram stool, and 95.7% (95%CI 93.2-97.7%) and 60.5% (95%CI 53.8-67.0%) respectively, at the limit of detection. The final pathway was 97% sensitive for CRC, compared with 90% for the current direct access criteria, and requires 47% fewer colonoscopies. Estimated prevalence of CRC among those declined investigation was 0.23%. CONCLUSION: Incorporating FIT in the new patient symptomatic pathway as presented appears feasible, safe, and allows for resources to be targeted to those at greatest risk of disease. Further work is needed to ensure equity for Maori if this pathway were introduced nationally.

Survey of New Zealand Arthroplasty Surgeons on Surgeon-Level Outcome Reporting.

BACKGROUND: Surgeon-specific outcome monitoring has become increasingly prevalent over the last 3 decades. The New Zealand Orthopaedic Association monitors individual surgeon performance through 2 mechanisms: arthroplasty revision rates derived from the New Zealand Joint Registry and a practice visit program. Despite remaining confidential, surgeon-level outcome reporting remains contentious. The purpose of this survey was to evaluate the opinions of hip and knee arthroplasty surgeons in New Zealand on the perceived importance of outcome monitoring, current methods used to evaluate surgeon-specific outcomes, and potential improvements identified through literature review and discussion with other registries. METHODS: The survey consisted of 9 questions on surgeon-specific outcome reporting, using a five-point Likert scale, and 5 demographic questions. It was distributed to all current hip and knee arthroplasty surgeons. There were 151 hip and knee arthroplasty surgeons who completed the survey, a response rate of 50%. RESULTS: Respondents agreed that monitoring arthroplasty outcomes is important and that revision rates are an acceptable measure of performance. Reporting risk-adjusted revision rates and more recent timeframes were supported, as was including patient-reported outcomes when monitoring performance. Surgeons did not support public reporting of surgeon-level or hospital-level outcomes. CONCLUSION: The findings of this survey support the use of revision rates to confidentially monitor surgeon-level arthroplasty outcomes and suggest that concurrent use of patient-reported outcome measures would be acceptable.

Intermediates during the Nucleation of Platinum Nanoparticles by a Reaction with Ethylene Glycol: Operando X-ray Absorption Spectroscopy Studies with a Microfluidic Cell.

Using operando X-ray absorption spectroscopy in a continuous-flow microfluidic cell, we have investigated the nucleation of platinum nanoparticles from aqueous hexachloroplatinate solution in the presence of the reducing agent ethylene glycol. By adjusting flow rates in the microfluidic channel, we resolved the temporal evolution of the reaction system in the first few seconds, generating the time profiles for speciation, ligand exchange, and reduction of Pt. Detailed analysis of the X-ray absorption near-edge structure and extended X-ray absorption fine structure spectra with multivariate data analysis shows that at least two reaction intermediates are involved in the transformation of the precursor H2PtCl6 to metallic platinum nanoparticles, including the formation of clusters with Pt-Pt bonding before complete reduction to Pt nanoparticles.

Humin Formation on SBA-15-pr-SO3H Catalysts during the Alcoholysis of Furfuryl Alcohol to Ethyl Levulinate: Effect of Pore Size on Catalyst Stability, Transport, and Adsorption.

Herein, the alcoholysis of furfuryl alcohol in a series of SBA-15-pr-SO3H catalysts with different pore sizes is reported. Elemental analysis and NMR relaxation/diffusion methods show that changes in pore size have a significant effect on catalyst activity and durability. In particular, the decrease in catalyst activity after catalyst reuse is mainly due to carbonaceous deposition, whereas leaching of sulfonic acid groups is not significant. This effect is more pronounced in the largest-pore-size catalyst C3, which rapidly deactivates after one reaction cycle, whereas catalysts with a relatively medium and small average pore size (named, respectively, C2 and C1) deactivate after two reaction cycles and to a lesser extent. CHNS elemental analysis showed that C1 and C3 experience a similar amount of carbonaceous deposition, suggesting that the increased reusability of the small-pore-size catalyst can be attributed to the presence of SO3H groups mostly present on the external surface, as corroborated by results on pore clogging obtained by NMR relaxation measurements. The increased reusability of the C2 catalyst is attributed to a lower amount of humin being formed and, at the same time, reduced pore clogging, which helps to maintain accessible the internal pore space.

Novel Amperometric Mercury-Selective Sensor Based on Organic Chelator Ionophore.

A novel amperometric sensor for the direct determination of toxic mercury ions, Hg2+, based on the organic chelator ionophore N, N di (2-hydroxy-5-[(4-nitrophenyl)diazenyl]benzaldehyde) benzene-1,2-diamine (NDBD), and multiwalled carbon nanotubes (MWCNT) immobilized on a glassy carbon electrode surface was developed. The parameters influencing sensor performance including the ionophore concentration, the applied potential, and electrolyte pH were optimized. The sensor response to Hg2+ was linear between 1-25 µM with a limit of detection of 60 nM. Interferences from other heavy metal ions were evaluated and the sensor showed excellent selectivity towards Hg2+. The method was successfully applied to the determination of mercury ions in milk and water samples.

Bimetallic Aluminum- and Niobium-Doped MCM-41 for Efficient Conversion of Biomass-Derived 2-Methyltetrahydrofuran to Pentadienes.

The production of conjugated C4-C5 dienes from biomass can enable the sustainable synthesis of many important polymers and liquid fuels. Here, we report the first example of bimetallic (Nb, Al)-atomically doped mesoporous silica, denoted as AlNb-MCM-41, which affords quantitative conversion of 2-methyltetrahydrofuran (2-MTHF) to pentadienes with a high selectivity of 91 %. The incorporation of AlIII and NbV sites into the framework of AlNb-MCM-41 has effectively tuned the nature and distribution of Lewis and Brønsted acid sites within the structure. Operando X-ray absorption, diffuse reflectance infrared and solid-state NMR spectroscopy collectively reveal the molecular mechanism of the conversion of adsorbed 2-MTHF over AlNb-MCM-41. Specifically, the atomically-dispersed NbV sites play an important role in binding 2-MTHF to drive the conversion. Overall, this study highlights the potential of hetero-atomic mesoporous solids for the manufacture of renewable materials.

Relationship between baseline cognition and 18-month treatment response in bipolar disorder.

BACKGROUND: To date, few studies have examined baseline cognitive function as a predictor of clinical outcome following treatment in bipolar disorder (BD). The aim of this analysis was therefore to examine the relationship between baseline cognitive function and treatment outcome in a sample of young adults with BD receiving Interpersonal Social Rhythm Therapy (IPSRT) or Specialist Supportive Care (SSC) with adjunctive pharmacotherapy. METHODS: Eighty-six BD patients underwent baseline cognitive testing and completed 18 months of IPSRT or SCC. Univariate analyses examined the relationship between baseline cognitive function (global and individual cognitive domains) and change in mood symptom burden, and psychosocial functioning, from baseline to treatment-end. RESULTS: Baseline global cognition was not predictive of change in mood symptom burden over 18 months of treatment. However, poorer baseline psychomotor speed performance was associated with less improvement in mood symptom burden at treatment-end. Neither baseline global cognition nor individual cognitive domain scores were associated with change in psychosocial functioning. LIMITATIONS: Due to the exploratory nature of the study, correction was not made for multiple comparisons. Data was obtained from a relatively small sample and has been the subject of prior analysis, thereby increasing the likelihood of chance findings. CONCLUSION: Although global cognition was not associated with outcome, when examining individual domains, poorer baseline psychomotor speed predicted less change in mood symptom burden following 18-months of psychotherapy and pharmacotherapy. This suggests that pre-treatment measures of psychomotor speed may help to identify those who require additional, and more targeted, intervention. Further large-scale research is required.

Burnout, stress and intentions to leave work in New Zealand psychiatrists; a mixed methods cross sectional study.

BACKGROUND: Demand for mental health services in New Zealand and internationally is growing. Little is known about how psychiatrists are faring in this environment. This study aimed to investigate wellbeing of psychiatrists working in the public health system in New Zealand, identify the main risk factors for work-related stress, gauge perceptions of how workload has changed over time, assess job satisfaction and whether individuals intend or desire to leave their work. METHODS: Psychiatrists working in New Zealand who were also members of the Association of Salaried Medical Specialists were invited to participate in an online survey. Main outcome measures were degree of burnout and stress experienced at work. Supplementary measures included perceived workplace demands and levels of support. Predictor variables included perceptions of changes to workloads over time, degree of job satisfaction and intentions to leave work. Logistic regression assessed characteristics associated with burnout and job satisfaction as well as intentions to leave work. Free text comments were analysed thematically alongside quantitative trends. RESULTS: 368/526 responded (70% response rate). 34.6% met the criteria for burnout and 35.3% scored with high work stress. There were no significant patterns of association with demographic variables but significant correlation with all but one predictor variable; having experienced a change to the demands of the on-call workload. 45% agreed they would leave their current job if able and 87% disagreed that they are working in a well-resourced mental health service. Respondents emphasised the impact of growing workloads and expressed concerns about their ability to provide optimal care in these circumstances. CONCLUSIONS: High burnout appears to affect one in three psychiatrists in New Zealand. Many attribute their feelings of burnout to demand for their services. These findings may assist with better workforce planning for psychiatry and emphasises potential consequences of demand for and poor resourcing of mental health services for the retention and wellbeing of doctors in psychiatry worldwide.

Electrochemical Impedance Spectroscopy in the Characterisation and Application of Modified Electrodes for Electrochemical Sensors and Biosensors.

Electrochemical impedance spectroscopy is finding increasing use in electrochemical sensors and biosensors, both in their characterisation, including during successive phases of sensor construction, and in application as a quantitative determination technique. Much of the published work continues to make little use of all the information that can be furnished by full physical modelling and analysis of the impedance spectra, and thus does not throw more than a superficial light on the processes occurring. Analysis is often restricted to estimating values of charge transfer resistances without interpretation and ignoring other electrical equivalent circuit components. In this article, the important basics of electrochemical impedance for electrochemical sensors and biosensors are presented, focussing on the necessary electrical circuit elements. This is followed by examples of its use in characterisation and in electroanalytical applications, at the same time demonstrating how fuller use can be made of the information obtained from complete modelling and analysis of the data in the spectra, the values of the circuit components and their physical meaning. The future outlook for electrochemical impedance in the sensing field is discussed.