Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Determinants of kidney transplant candidates' decision to accept organ donor intervention transplants and participate in post-transplant research: A conjoint analysis

Deceased organ donor intervention research aims to increase organ quality and quantity for transplantation. We assessed the proportion of kidney transplant candidates who would accept "intervention organs," participate in organ intervention research, and factors influencing acceptance. Kidney transplant candidates were presented 12 hypothetical scenarios, which varied three attributes, donor age, predicted waiting time to receive another organ offer, and research risk to the organ. Candidates were also randomly assigned to one of two conditions varying recipient risk. For each scenario, candidates agreed to accept the intervention organ or remain waitlisted. We fit a multivariable logit model to determine the association between scenario attributes and the acceptance decision. Of 249 participants, most (96%) accepted intervention organs under some or all conditions. Factors independently associated with candidates' greater likelihood of accepting an intervention organ included: low risk to the kidney from the intervention (OR 20.53 [95% Confidence Interval (CI), 13.91-30.29]); younger donor age (OR 3.72 [95% CI, 2.83-4.89]), longer time until the next organ offer (OR 3.48 [95% CI, 2.65-4.57]), and greater trust in their transplant physician (OR 1.03 [95% CI, 1.00-1.06]). Candidates with a lower likelihood of acceptance had been waitlisted longer (OR 0.97 per month [95% CI, 0.96-0.99]) and were Black (OR 0.21 [95% CI, 0.08-0.55]). Most candidates would accept an intervention organ, which should encourage transplant leaders to conduct deceased donor organ intervention trials.

Perspectives of hematology oncology clinicians about integrating palliative care in oncology

Patients with hematologic malignancies receive palliative care (pc) less frequently and later than patients with solid tumours. We compared survey responses of hematology oncology clinicians with other oncology clinicians to better understand their challenges with providing primary pc or using secondary pc. Patients' negative perceptions of pc and limited time or competing priorities were challenges for all clinicians. Compared with other oncology clinicians, more hematology oncology clinicians perceived pc referral criteria as too restrictive (40% vs. 22%, p = 0.021) and anticipated that integrating pc supports into their practice would require substantial change (53% vs. 28%, p = 0.014). This study highlights barriers that may need targeted interventions to better integrate pc into the care of patients with hematologic malignancies.

A Study of Concerns of Families of Potential Donation After Circulatory Death Donors and Recommendations for Raising Donation Rates

CONTEXT

The request process for donation after circulatory death (DCD) and family concerns about DCD differ in significant ways from the process for, and family concerns about, donation after brain death (DBD). In addition, donation rates for DCDs are typically lower than for DBDs. Although there has been a great deal of research on how the concerns of DBD families impact donation, limited research exists on family concerns and decision-making in the DCD request process.

OBJECTIVE

To determine the concerns of families approached for DCD and explore how those might be addressed to increase DCD donation rates.

DESIGN, SETTING, AND PARTICIPANTS

Written request response forms were completed by organ procurement and family services coordinators from 4 organ procurement organizations in 4 different states. They were filled out as soon as possible after speaking with families about DCD.

MAIN OUTCOME MEASURES

Responses were marked on a 12-item instrument, and anecdotal observations and detailed comments about family concerns, donor registration status, and decisions made were noted.

RESULTS

Family concerns that block DCDs differ in many ways from those that block DBDs. These concerns arise from stresses peculiar to the DCD situation and must be addressed for these types of donations to increase.

PURPOSE OF THE STUDY

The purposes of the study are to identify family concerns about donating organs that are specific to DCD and that may differ from DBD and to distinguish how those concerns might be addressed in ways that increase the likelihood of donation.

Solid organ donation after death in the United States: Data-driven messaging to encourage potential donors

US deceased donor solid organ transplantation (dd-SOT) depends upon an individual's/family's altruistic willingness to donate organs after death; however, there is a shortage of deceased organ donors in the United States. Informing individuals of their own lifetime risk of needing dd-SOT could reframe the decision-making around organ donation after death. Using United Network for Organ Sharing (UNOS) data (2007-2016), this cross-sectional study identified (1) deceased organ donors, (2) individuals waitlisted for dd-SOT (liver, kidney, pancreas, heart, lung, intestine), and (3) dd-SOT recipients. Using US population projections, life tables, and mortality estimates, we quantified probabilities (Pr) of (1) becoming deceased organ donors, (2) needing dd-SOT, and (3) receiving dd-SOT. Lifetime Pr (per 100 000 US population) for males and females of becoming deceased organ donors were 212 and 146, respectively, and of needing dd-SOT were 1323 and 803, respectively. Lifetime Pr of receiving dd-SOT was 50% for males, 48% for females. Over a lifetime, males were 6.2 and females 5.5 times more likely to need dd-SOT than to become deceased organ donors. Organ donation is traditionally contextualized in terms of charity toward others. Our analyses yield a new tool, in the form of quantifying an individual's own likelihood of needing dd-SOT, which may assist with reframing motivations toward deceased donor organ donation.

Transplant candidates' perceptions of informed consent for accepting deceased donor organs subjected to intervention research and for participating in posttransplant research

Deceased donor organ intervention research holds promise for increasing the quantity and quality of organs for transplantation by minimizing organ injury and optimizing function. Such research will not progress until ethical, regulatory, and legal issues are resolved regarding whether and how to obtain informed consent from transplant candidates offered intervention organs given time constraints intrinsic to distribution. This multi-center, mixed-methods study involved semi-structured interviews using open- and closed-ended questions to assess waitlisted candidates' preferences for informed consent processes if offered an organ after undergoing intervention. Data were analyzed thematically. Sixty-one candidates participated (47% participation rate). Most were male (57%), white (61%), with a mean age of 56 years. Most candidates (79%) desired being informed that the organ offered was an intervention organ before accepting it, and were likely to accept an intervention organ if organ quality was good (defined as donor age 30) (81%), but fewer candidates would accept an intervention organ if quality was moderate (ie, donor age 50) (26%). Most perceived informed consent important for decision-making, while others considered it unnecessary given medical necessity to accept an organ and trust in their physician. Our findings suggest that most candidates desire an informed consent process before accepting an intervention organ and posttransplant data collection.

Pediatric sacral nerve stimulator explanation due to complications or cure: a survival analysis

INTRODUCTION

Historically, there have been few treatment options for children with severe refractory bladder and bowel dysfunction (BBD). Sacral neuromodulation (SNM) continues to show promising results in this challenging pediatric population with recalcitrant lower urinary tract symptoms. At the authors institution, they have begun offering explantation to those with persistent improvement after >6 months of having device turned off. The authors hypothesized that (1) SNM explantation for cure increases with extended follow-up and (2) those explanted for cure would have improved symptoms and quality of life when compared to those explanted for complication.

MATERIALS & METHODS

The authors retrospectively reviewed all consecutive patients aged <18 years who underwent SNM placements at their institution (2012-2017). They excluded those without the second stage procedure. Reasons for device explantation were categorized as cure (resolution of symptoms with the device turned off for at least 6 months) or a complication (e.g. infection, need for magnetic resonance imaging, or pain). Non-parametric tests and survival analysis were used for analysis to account for differential follow-up time. Of those explanted, surveys were electronically sent to assess BBD severity and overall quality of life.

RESULTS

Of 67 children who underwent a first stage procedure, 62 (92.5%) underwent a second stage procedure. 61 met inclusion criteria (68.9% female, 29.5% with previous filum section, median age at implantation 10.3 years). During follow-up (median 2.3 years), 12 patients (19.7%) had the SNM exchanged/revised because of lead fracture/breakage and return of urinary symptoms. To date, 50 patients remain with their SNM implanted, and 11 have been explanted. Adjusting for follow-up time, the risk of explantation was 6.5% at 2 years (2.2% for cure, 4.3% for complications) (Figure 1). Explantation increased to 24.5% at 3 years (16.5% for cure, 8.0% for complications) and 40.4% at 4 years (32.4% for cure, 8.0% for complications). Questionnaires were collected on patients after explant (median 2.2 years), with improvement in those explanted for cure compared to complication (Figure 2).

DISCUSSION

Sacral neuromodulation explantation for cure is a novel concept previously not described in the literature. Limitations of this study include the relatively small numbers and lack of objective data in the cohort that remains with SNM device implanted.

CONCLUSION

Sacral neuromodulation is a safe, viable option for the pediatric patient with refractory bladder dysfunction. Furthermore, SNM explantation for cure is an option with increasing likelihood after 2 years.

Mortality of civilian patients with suspected traumatic haemorrhage receiving pre-hospital transfusion of packed red blood cells compared to pre-hospital crystalloid

Background

Major haemorrhage is a leading cause of mortality following major trauma. Increasingly, Helicopter Emergency Medical Services (HEMS) in the United Kingdom provide pre-hospital transfusion with blood products, although the evidence to support this is equivocal. This study compares mortality for patients with suspected traumatic haemorrhage transfused with pre-hospital packed red blood cells (PRBC) compared to crystalloid.

Methods

A single centre retrospective observational cohort study between 1 January 2010 and 1 February 2015. Patients triggering a pre-hospital Code Red activation were eligible. The primary outcome measure was all-cause mortality at 6 hours (h) and 28 days (d), including a sub-analysis of patients receiving a major and massive transfusion. Multivariable regression models predicted mortality. Multiple Imputation was employed, and logistic regression models were constructed for all imputed datasets.

Results

The crystalloid (n = 103) and PRBC (n = 92) group were comparable for demographics, Injury Severity Score (p = 0.67) and mechanism of injury (p = 0.73). Observed 6 h mortality was smaller in the PRBC group (n = 10, 10%) compared to crystalloid group (n = 19, 18%). Adjusted OR was not statistically significant (OR 0.48, CI 0.19–1.19, p = 0.11). Observed mortality at 28 days was smaller in the PRBC group (n = 21, 26%) compared to crystalloid group (n = 31, 40%), p = 0.09. Adjusted OR was not statistically significant (OR 0.66, CI 0.32–1.35, p = 0.26). A statistically significant greater proportion of the crystalloid group required a major transfusion (n = 62, 60%) compared to the PRBC group (n = 41, 40%), p = 0.02. For patients requiring a massive transfusion observed mortality was smaller in the PRBC group at 28 days (p = 0.07).

Conclusion

In a single centre UK HEMS study, in patients with suspected traumatic haemorrhage who received a PRBC transfusion there was an observed, but non-significant, reduction in mortality at 6 h and 28 days, also reflected in a massive transfusion subgroup. Patients receiving pre-hospital PRBC were significantly less likely to require an in-hospital major transfusion. Further adequately powered multi-centre prospective research is required to establish the optimum strategy for pre-hospital volume replacement in patients with traumatic haemorrhage.

Lay health educators within primary care practices to improve cancer screening uptake for South Asian patients: challenges in quality improvement

BACKGROUND

Cancer screening uptake is known to be low among South Asian residents of Ontario. The objective of this pilot study was to determine if lay health educators embedded within the practices of primary care providers could improve willingness to screen and cancer screening uptake for South Asian patients taking a quality improvement approach.

MATERIALS AND METHODS

Participating physicians selected quality improvement initiatives to use within their offices that they felt could increase willingness to screen and cancer screening uptake. They implemented initiatives, adapting as necessary, for six months.

RESULTS

Four primary care physicians participated in the study. All approximated that at least 60% of their patients were of South Asian ethnicity. All physicians chose to work with a preexisting lay health educator program geared toward South Asians. Health ambassadors spoke to patients in the office and telephoned patients. For all physicians, ~60% of South Asian patients who were overdue for cancer screening and who spoke directly to health ambassadors stated they were willing to be screened. One physician was able to track actual screening among contacted patients and found that screening uptake was relatively high: from 29.2% (colorectal cancer) to 44.6% (breast cancer) of patients came in for screening within six months of the first phone calls. Although physicians viewed the health ambassadors positively, they found the study to be time intensive and resource intensive, especially as this work was additional to usual clinical duties.

DISCUSSION

Using South Asian lay health educators embedded within primary care practices to telephone patients in their own languages showed promise in this study to increase awareness about willingness to screen and cancer screening uptake, but it was also time intensive and resource intensive with numerous challenges. Future quality improvement efforts should further develop the phone call invitation process, as well as explore how to provide infrastructure for lay health educator training and time.

Perovskite BiFeO3 thin film photocathode performance with visible light activity

Perovskite materials are now an important class of materials in the application areas of photovoltaics and photocatalysis. Inorganic perovskites such as BiFeO3 (BFO) are promising photocatalyst materials with visible light activity and inherent stability. Here we report the large area sol-gel synthesis of BFO films for solar stimulated water photo oxidation. By modifying the sol-gel synthesis process we have produced a perovskite material that has p-type behaviour and a flat band potential of ∼1.15 V (versus NHE). The photocathode produces a density of -0.004 mA cm(-2) at 0 V versus NHE under AM1.5 G illumination. We further show that 0.6 μmol h(-1) of O2 was produced at an external bias of -0.5 V versus Ag/AgCl. The addition of a non-percolating conducting network of Ag increases the photocurrent to -0.07 mA cm(-2) at 0 V versus NHE (at 2% Ag loading) with an increase to 2.7 μmol h(-1) for O2 production. We attribute the enhancement in photoelectrochemical performance to increased light absorption due light scattering by the incorporated Ag particles, improved charge transfer kinetics at the Ag/BFO interface and reduced over potential losses. We support these claims by an observed shift in flat band and onset potentials after Ag modification through UV-vis spectroscopy, Mott-Schottky plots and j-v curve analysis.

Shared decision making for infants born at the threshold of viability: a prognosis-based guideline

OBJECTIVE

Making prenatal decisions regarding resuscitation of extremely premature infants, based on gestational age alone is inadequate. We developed a prognosis-based guideline.

STUDY DESIGN

We followed a five step approach and used the AGREE II framework: (1) systematic review and critical appraisal of published guidelines; (2) identification of key medical factors for decision making; (3) systematic reviews; (4) creation of a multi-disciplinary working group and (5) external consultation and appraisal.

RESULT

No published guideline met high-quality appraisal criteria. Survival, neurodevelopmental disability, quality of life of child and parents, and maternal mortality and risk of long-term morbidity were identified as key for quality decision-making. Eighteen stakeholders (including parents) advocated for the incorporation of parents' values and preferences in the process.

CONCLUSION

A novel framework, based on prognosis, was generated to guide when early intensive and palliative care may both be offered to expectant parents. Pre-implementation assessment is underway to identify barriers and facilitators to putting in practice.

Primary care physicians' perceptions about and confidence in deciding which patients to refer for total joint arthroplasty of the hip and knee

OBJECTIVE

The purpose of this study is to examine the perceptions of primary care physicians (PCPs) regarding indications, contraindications, risks and benefits of total joint arthroplasty (TJA) and their confidence in selecting patients for referral for TJA.

DESIGN

PCPs recruited from among those providing care to participants in an established community cohort with hip or knee osteoarthritis (OA). Self-completed questionnaires were used to collect demographic and practice characteristics and perceptions about TJA. Confidence in referring appropriate patients for TJA was measured on a scale from 1 to 10; respondents scoring in the lowest tertile were considered to have 'low confidence'. Descriptive analyses were conducted and multiple logistic regression was used to determine key predictors of low confidence.

RESULTS

212 PCPs participated (58% response rate) (65% aged 50+ years, 45% female, 77% >15 years of practice). Perceptions about TJA were highly variable but on average, PCPs perceived that a typical surgical candidate would have moderate pain and disability, identified few absolute contraindications to TJA, and overestimated both the effectiveness and risks of TJA. On average, PCPs indicated moderate confidence in deciding who to refer. Independent predictors of low confidence were female physicians (OR = 2.18, 95% confidence interval (CI): 1.06-4.46) and reporting a 'lack of clarity about surgical indications' (OR = 3.54, 95% CI: 1.87-6.66).

CONCLUSIONS

Variability in perceptions and lack of clarity about surgical indications underscore the need for decision support tools to inform PCP - patient decision making regarding referral for TJA.

Plasmon enhanced visible light photocatalysis for TiO2 supported Pd nanoparticles

A photocatalyst consisting of nanostructured Pd photochemically deposited on 20 nm TiO2 displays a reaction half-life for rhodamine b decolourisation of 0.5 minute compared to the 9.4 minutes for unmodified P25 under identical reaction conditions. We associate this increased decolourisation rate to the increase in solar light harvesting which we have measured at 8% due to a significant red shift in the absorption profile of the catalyst. We relate the increased absorption of light with a visible active plasmon effect that is associated with the Pd nanostructures on the TiO2. This overall red-shift in the light harvesting for the catalyst leads to photocatalytic activity for excitations up to 600 nm.

Reduction of noise in the neonatal intensive care unit using sound-activated noise meters

OBJECTIVES

To determine if sound-activated noise meters providing direct audit and visual feedback can reduce sound levels in a level 3 neonatal intensive care unit (NICU).

DESIGN/METHODS

Sound levels (in dB) were compared between a 2-month period with noise meters present but without visual signal fluctuation and a subsequent 2 months with the noise meters providing direct audit and visual feedback.

RESULTS

There was a significant increase in the percentage of time the sound level in the NICU was below 50 dB across all patient care areas (9.9%, 8.9% and 7.3%). This improvement was not observed in the desk area where there are no admitted patients. There was no change in the percentage of time the NICU was below 45 or 55 dB.

CONCLUSIONS

Sound-activated noise meters seem effective in reducing sound levels in patient care areas. Conversations may have moved to non-patient care areas preventing a similar change there.

Examining the effects of a targeted noise reduction program in a neonatal intensive care unit

OBJECTIVES

To determine whether implementation of a noise reduction policy followed by the addition of direct audit and feedback reduces noise levels in a tertiary-level neonatal intensive care unit (NICU).

STUDY DESIGN

Noise level data was collected in three phases: (1) baseline (preintervention), (2) immediately postimplementation of our noise reduction policy, (3) postunveiling of direct audit and feedback mechanism.

SETTING

A level 3 NICU in Ontario, Canada.

INTERVENTIONS

Noise reduction policy and a direct audit and feedback mechanism.

MAIN OUTCOME MEASURES

Average noise level.

RESULTS

The baseline level of noise in our unit consistently exceeds guidelines with an average baseline noise of 49 dB (±1.4). Our intervention resulted in a significant reduction in noise levels for one of the four areas in our NICU [-1.06 dB (-1.52, -0.6)], with a trend towards reduction in a second area (-0.21 dB (-0.6, 0.18)). Unexpectedly, two other areas experienced a significant increase in noise (2.05 dB (1.18, 2.94); 0.85 dB (0.11, 1.59)).

CONCLUSIONS

The baseline noise in the NICU consistently exceeds guidelines, but reductions in noise levels are achievable. Nonetheless, more work is needed to find the optimal NICU design and noise reduction strategy.

Effluent Storage and Biomat Occurrence among Septic System Absorption Field Architectures in a Typic Fragiudult

On-site wastewater treatment systems (OWTSs) are commonly used by households in areas of low population density to treat household wastewater and recycle it back to the environment. However, new absorption field products of differing architecture types have recently become available. A 3-yr field study was conducted in Bethel Heights, northwest Arkansas to assess several newer architecture types (i.e., chambers, polystyrene-aggregate, and gravel-less pipe) relative to the traditional pipe-and-gravel design under wet- and dry-soil conditions. Thirteen products of four different architecture types were installed in 46-cm-deep trenches in a Captina silt loam (fine-silty, siliceous, active, mesic Typic Fragiudult). Products were evaluated based on in-trench solution storage measured with an electronic water-level sensor approximately weekly from January 2009 through January 2012. Between May 2010 and January 2012, the thickness of any biomat formation was measured approximately weekly by insertion of a wooden dowel through in-trench monitoring ports. Architecture type alone did not affect ( > 0.05) in-trench solution storage. However, solution storage among individual products differed under wet- and dry-soil conditions ( < 0.05). When present, biomat thickness differed significantly ( < 0.05) among all four architecture types, ranging from 1.4 to 6.2 cm thick on average in the pipe-and-aggregate and polystyrene-aggregate types, respectively. Regression analyses showed that biomat thickness increased in three products, did not change in nine products, and decreased in one product over time. Results showed that several currently approved alternative products had similar in-trench solution storage but that several alternative products also had greater solution storage than that of the traditional pipe-and-gravel system. With no observed effluent surfacing, the soil morphology approach appears to be adequate and appropriately environmentally conservative for assigning typical single-family loading rates to alternative OWTS products and to the traditional pipe-and-gravel system.

Non-ST-elevation myocardial infarction following foam ultrasound-guided sclerotherapy

The objective of the study was to describe a very rare complication of foam ultrasound-guided sclerotherapy (FUGS). An unusual case of persisting chest discomfort following FUGS in a 61-year-old woman led to a diagnosis of non-ST-elevation myocardial infarction. The patient was found to have a patent foramen ovale (PFO). The differential diagnoses of paradoxical embolism, gas embolism or vasospasm are discussed, with reference to relevant literature. A hypothesis of post sclerotherapy release of endothelin-1 (in a patient with a known PFO) leading to sustained coronary artery spasm causing sufficient myocardial damage to be reflected in elevated troponin levels is suggested.

Any episode of chest tightness or pain following FUGS should be considered as possibly cardiac in origin. Sustained symptoms warrant admission to hospital for troponin monitoring and ECG assessment.

2008 Niday Perinatal Database quality audit: report of a quality assurance project

INTRODUCTION

This quality assurance project was designed to determine the reliability, completeness and comprehensiveness of the data entered into Niday Perinatal Database.

METHODS

Quality of the data was measured by comparing data re-abstracted from the patient record to the original data entered into the Niday Perinatal Database. A representative sample of hospitals in Ontario was selected and a random sample of 100 linked mother and newborn charts were audited for each site. A subset of 33 variables (representing 96 data fields) from the Niday dataset was chosen for re-abstraction.

RESULTS

Of the data fields for which Cohen's kappa statistic or intraclass correlation coefficient (ICC) was calculated, 44% showed substantial or almost perfect agreement (beyond chance). However, about 17% showed less than 95% agreement and a kappa or ICC value of less than 60% indicating only slight, fair or moderate agreement (beyond chance).

DISCUSSION

Recommendations to improve the quality of these data fields are presented.

The photochemical growth of silver nanoparticles on semiconductor surfaces--initial nucleation stage

Questions surrounding the nucleation mechanism for nanostructures that are grown on semiconductors, such as lead zirconate titanate, using photochemical techniques have ranged from 'What is the nucleation process?' to 'Is it possible to produce homogeneous nanoscale patterns?' Here we demonstrate that nucleation occurs at discrete locations on the surface of the substrate that are indicative of a disruption of the local Stern layer due to a local defect or electric field in the substrate. The band diagram for the system is such that when a cluster forms it is possible for electrons to migrate into the silver metal and so replace the surface positive charge, associated with the positive domain of the ferroelectric, with a local negative charge. Once the initial cluster starts to form, the rate of growth of an individual cluster increases due to a restructuring of the Stern layer and increased probability of reaction of an electron with the cations in solution. We show that the nucleation density does not change significantly from the initial nucleation density, and that approximately 15% of the particles that form on the surface are 50% larger than the other particles. The reasons for no significant change in nucleation density stem from the concentration of available disrupted locations in the Stern layer, and variations in the growth rate are discussed in terms of the local electric field and defect influences.