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Background Organ transplant recipients (OTRs) have up to 500-fold increased risk of keratinocyte skin cancer (KSC). International guidelines recommend at least annual skin cancer screening for OTRs. Objectives To explore the current skin cancer surveillance practice in UK transplant centres across all solid organs and the barriers to surveillance. Materials and methods An online survey was sent to all 59 transplant centres in the UK specialising in kidney (n = 24), pancreas (n = 10), heart and/or lung (n = 13), liver (n = 8) and intestine (n = 4) transplants. Results Fifty-one (86%) transplant centres responded. Twenty-eight (55%) centres provided skin cancer surveillance post-transplantation, of which 18 (64%) had a non-skin cancer specialist providing screening. Only 21 (41%) units performed a full skin examination. Eight units (29%) screened at least bi-annually in the first five years post-transplantation. Of the 23 (45%) centres that did not provide skin cancer surveillance, limitations included: reliance on patient-reported lesions (48%), lack of skin surveillance training (30%), lack of funding (48%), not a requirement in all patients (17%) and time restraints in the clinic (30%). Conclusion In the UK, many transplant units do not provide skin surveillance. Collaboration between skin cancer and transplant specialists would improve surveillance rates and reduce morbidity and mortality.

Circumferential deep burns on the limb lead to a constrictive, tourniquet-like effect causing critical limb ischaemia. The treatment, escharotomy, is a time-critical procedure that sometimes is required before the patient arrives at a burn centre. At present, no practical method of teaching this procedure is incorporated into formal educational courses.The feasibility of a comprehensive education package to teach upper limb escharotomy was assessed in a group of plastic and general surgery trainees in Wales. Small group workshops focused on the clinical presentation of patients requiring escharotomy. Participants then executed this on a custom-made high-fidelity simulation upper limb model. The articulated limb has subcutaneous silicone fat which bulges upon decompression and a finger-tip which turns pink indicating satisfactory reperfusion. A before and after five-point Likert scale was used to evaluate changes in participants' self-assessed confidence in the surgical management of escharotomy. Statistical significance between scores was assessed using the Wilcoxon signed-rank test.A total of 34 participants took part. Following completion of the course, general surgery trainees' confidence in executing the procedure increased from a median score of 1.00 "not confident at all" (IQR 1.00-2.00) to 4.00 "fairly confident" (IQR 4.00-5.00, p 0.01). Plastic surgery trainees' confidence increased from a median score of was 3.00 "somewhat confident" (IQR 1.75-4.00) to 4.00 "fairly confident" (IQR 3.00-4.25, p 0.01).We developed a comprehensive simulator course that has been demonstrated to improve candidate's confidence in performing escharotomy. The next stage in the course development is to confirm the results in a larger cohort. By developing this simulator course we aim to improve emergency burn care education in the UK and globally.

Introduction The severity of Covid-19 infection is associated with viral load. For infection to occur, viruses including SARS-CoV-2 must first penetrate the respiratory mucus to attach to the host cell surface receptors. Iota-carrageenan (I-C), a sulphated polysaccharide extracted from red edible seaweed, has shown efficacy against a range of viruses in clinical trials, through prevention of viral entry into respiratory host cells and in-vitro activity against SARS-CoV-2. Our aim, as an academic surgical department, was to design and implement a clinical trial to investigate whether I-C nasal and throat sprays are effective in reducing the rate and severity of Covid-19 infection. Method The study is a single centre, double-blinded randomised controlled trial. Recruitment of 480 participants aged ≥18 years without previous Covid-19 infection and who have not yet been vaccinated, commenced in December 2020. Participants are randomised to either the treatment (0.12% I-C in 0.5% saline spray) or placebo (0.5% saline spray) arm and will prophylactically apply the spray to their nose and throat while completing a daily symptom tracker for a total of 10 weeks. The primary outcome is the acquisition of Covid-19 infection. Secondary outcomes include symptom type, severity and duration, subsequent familial/household Covid-19 infection and infection with non-Covid-19 upper respiratory tract infections. Discussion Our hypothesis is that I-C sprays will reduce SARS-CoV-2 attachment to the naso- and oropharyngeal mucosal epithelial cells thus reducing the effective viral infective dose. If proven effective, the self-administered prophylactic spray would have wider utility for key workers and the general population. Trial registration number NCT04590365

Skin cancer is more common in transplant recipients, although the quoted incidence is variable. This study investigated the incidence of skin cancer in solid organ transplant recipients (OTRs) in a national cohort and the effect of pharmacotherapeutic agents Transplant patients were identified from Patient Episode Database for Wales (PEDW) using Office of Population Census and Surveys Classifications of Interventions and Procedures-4 (OPCS-4) codes. Controls were matched to cases according to age, sex and socioeconomic status. Skin cancer data were obtained from linkage with other national data sources. Incidence was calculated per 100,000 person-years at risk (PYAR). Negative binomial regression was used to calculate adjusted incidence rate ratios (IRRs) for each organ type. During 2000-2018, 2,852 Welsh patients underwent solid organ transplantation. A total of 13,527 controls were matched from the general population. The incidence of skin cancer within the OTR cohort was 1203.2 per 100,000 PYAR vs 133.9 in the matched control group. Age, male gender and azathioprine use were all associated with an increased risk of skin cancer. Contemporary immunomodulators such as tacrolimus and mycophenolate were associated with a reduction in skin cancer risk when compared to their predecessors, cyclosporin and azathioprine. The highest adjusted IRR was observed in heart transplant recipients (IRR: 10.82; 95% CI: 3.64-32.19) and the lowest in liver transplant recipients (IRR: 2.86; 95% CI: 1.15-7.13). This study highlights the need for long-term routine skin cancer surveillance for all OTRs and the importance of using contemporary immunomodulators, when possible, for risk reduction.

Background Previous studies have identified an inverse association between melanoma and smoking; however, data from population-based studies are scarce. Objectives To determine the association between smoking and socioeconomic (SES) on the risk of development of melanoma. Furthermore, we sought to determine the implications of smoking and SES on survival. Methods We conducted a population-based case-control study. Cases were identified from the Welsh Cancer Intelligence and Surveillance Unit (WCISU) during 2000-2015 and controls from the general population. Smoking and SES were obtained from data linkage with other national databases. The association of smoking status and SES on the incidence of melanoma were assessed using binary logistic regression. Multivariate survival analysis was performed on a melanoma cohort using a Cox proportional hazard model using survival as the outcome. Results During 2000-2015, 9636 patients developed melanoma. Smoking data were obtained for 7124 (73·9%) of these patients. There were 26 408 controls identified from the general population. Smoking was inversely associated with melanoma incidence [odds ratio (OR) 0·70, 95% confidence interval (CI) 0·65-0·76]. Smoking was associated with an increased overall mortality [hazard ratio (HR) 1·30, 95% CI 1·09-1·55], but not associated with melanoma-specific mortality. Patients with higher SES had an increased association with melanoma incidence (OR 1·58, 95% CI 1·44-1·73). Higher SES was associated with an increased chance of both overall (HR 0·67, 95% CI 0·56-0·81) and disease-specific survival (HR 0·69, 95% CI 0·53-0·90). Conclusions Our study has demonstrated that smoking appeared to be associated with reduced incidence of melanoma. Although smoking increases overall mortality, no association was observed with melanoma-specific mortality. Further work is required to determine if there is a biological mechanism underlying this relationship or an alternative explanation, such as survival bias. What's already known about this topic? Previous studies have been contradictory with both negative and positive associations between smoking and the incidence of melanoma reported. Previous studies have either been limited by publication bias because of selective reporting or underpowered. What does this study add? Our large study identified an inverse association between smoking status and melanoma incidence. Although smoking status was negatively associated with overall disease survival, no significant association was noted in melanoma-specific survival. Socioeconomic status remains closely associated with melanoma. Although higher socioeconomic populations are more likely to develop the disease, patients with lower socioeconomic status continue to have a worse prognosis.

The effect of hydrothermal ageing on the mechanical behaviour and fatigue response of a hybrid (bolted/bonded) aluminium alloy (AA7075) and glass fibre reinforced epoxy (GRE) hybrid composite single lap joints (SLJs) were carried out in this work. This effect was investigated using hybrid joints as a joint configuration. An adhesive layer of Araldite epoxy and mechanical fasteners of Huck bolt were attached between the adherends as primary and secondary attachments, respectively. Three types of joint were exposed to a humid environment at 50 °C for long-term immersion (20, 40, 60, 80, 100, and 120 days) periods. Composite laminates (i.e. glass fibre epoxy GRE) and metal (i.e. aluminium alloy AA7075) were used as joint adherends. Quasi-static and fatigue tests were carried out to evaluate the evolution of the mechanical performance and the damage mechanisms of hybrid joints during the ageing exposition. The dissimilar-AA7075/GRE hybrid SLJ showed the highest joint strength and the longest failure strain. Moreover, the hybrid joint with dissimilar-AA7075/GRE achieved 83% and 30.2% higher fatigue strength than similar adherends of AA7075 and GRE composites, respectively. As for the damage mechanisms, shear specimens experienced a typical bearing mode.

A Pennisetum purpureum/glass-reinforced epoxy (PGRE) hybrid composites was comprehensively characterised to assess its impact response behaviour at room temperature (RT), under moisture exposure, and elevated temperatures. The untreated, 5 and 10% alkali-treated PGRE composites were fabricated using hybridised Pennisetum purpureum/woven E-glass fibres and epoxy resin. An instrumented IMATEK IM10 drop weight impact tester was utilised to characterise the impact responses of the prepared hybrid composites. The specimens were subjected to water exposure for 50, 100, 200, and 400 h and before arranged with a low-velocity impact test. In addition, the tests were repeated at 40, 60, and 80 °C to examine the effects of elevated temperatures. The results indicate that the untreated PGRE composite yielded the highest peak load impact response at all energy levels. The stiffness of the composites found to decrease substantially with increasing temperatures, which increases the absorbed energy and peak deflection causing extensive damage to the specimens.

The FACE-Q Skin Cancer module is a patient-reported outcome measure (PROM) for facial skin cancer. It has been anglicised for the UK population and undergone psychometric testing using classical test theory. In this study, further evaluation of construct validity using Rasch measurement theory and hypothesis testing was performed.Patients were prospectively recruited to the Patient-Reported Outcome Measures In Skin Cancer Reconstruction (PROMISCR) study and asked to complete the anglicised FACE-Q Skin Cancer module. The scalability and unidimensionality of the data were assessed with a Mokken analysis prior to Rasch analysis. Response thresholds, targeting, fit statistics, local dependency, and internal consistency were examined for all items and subscales. Four a priori hypotheses were tested to evaluate the convergent and divergent validity. We additionally hypothesised that the median 'cancer worry' score would be lower in post-operative than pre-operative patients.239 patients self-completed the questionnaire between August 2017 and May 2019. Of the ten subscales assessed, five showed relative fit to the Rasch model. Unidimensionality was present for all five subscales, with most demonstrating ordered item thresholds and appropriate fit statistics. Two items in the 'cancer worry' subscale had either disordered or very close response thresholds. Subscales of the FACE-Q Skin Cancer module demonstrated convergent and divergent validity with relevant Skin Cancer Index comparators (p 0.001). Median 'cancer worry' was lower in post-operative patients (44 vs 39, p 0.001).The anglicised FACE-Q Skin Cancer module shows psychometric validity through hypothesis testing, and both classical and modern test theory.

ObjectivesTo report the volume of surgical activity and the number of cancelled surgical procedures during the COVID-19 pandemic.Design and settingAnalysis of electronic health record data from the National Health Service (NHS) in England and Wales.MethodsWe used hospital episode statistics for all adult patients undergoing surgery between 1st January 2020 and 31st December 2020. We identified surgical procedures using a previously published list of procedure codes. Procedures were stratified by urgency of surgery as defined by NHS England. We calculated the deficit of surgical activity by comparing the expected number of procedures from the years 2016-2019 with the actual number of procedures in 2020. We estimated the cumulative number of cancelled procedures by 31st December 2021 according patterns of activity in 2020.ResultsThe total number of surgical procedures carried out in England and Wales in 2020 was 3,102,674 compared to the predicted number of 4,671,338. This represents a 33.6% reduction in the national volume of surgical activity. There were 763,730 emergency surgical procedures (13.4% reduction), compared to 2,338,944 elective surgical procedures (38.6% reduction). The cumulative number of cancelled or postponed procedures was 1,568,664. We estimate that this will increase to 2,358,420 by 31st December 2021.ConclusionsThe volume of surgical activity in England and Wales was reduced by 33.6% in 2020, resulting in over 1,568,664 cancelled operations. This deficit will continue to grow in 2021.Summary boxesWhat is already known on this topicThe COVID-19 pandemic necessitated a rapid change in the provision of care, including the suspension of a large proportion of surgical activitySurgical activity has yet to return to normal and has been further impacted by subsequent waves of the pandemicThis will lead to a large backlog of casesWhat this study adds3,102,674 surgical procedures were performed in England and Wales during 2020, a 33.6% reduction on the expected yearly surgical activityOver 1.5 million procedures were not performed, with this deficit likely to continue to grow to 2.3 million by the end of 2021This deficit is the equivalent of more than 6 months of pre-pandemic surgical activity, requiring a monumental financial and logistic challenge to manage

ObjectivesTo confirm the incidence of perioperative SARS-CoV-2 infection and associated mortality after surgery.Design and settingAnalysis of routine electronic health record data from National Health Service (NHS) hospitals in England.MethodsWe extracted data from Hospital Episode Statistics in England describing adult patients undergoing surgery between 1st January 2020 and 31st October 2020. The exposure was SARS-CoV-2 infection defined by ICD-10 codes. The primary outcome measure was 90-day in-hospital mortality. Data were analysed using multivariable logistic regression adjusted for age, sex, Charlson co-morbidity index, index of multiple deprivation, presence of cancer, surgical procedure type and admission acuity. Results are presented as n (%) and odds ratios (OR) with 95% confidence intervals.ResultsWe identified 1,972,153 patients undergoing surgery of whom 11,940 (0.6%) had SARS-CoV-2. In total, 19,100 (1.0%) patients died in hospital. SARS-CoV-2 infection was associated with a much greater risk of death (SARS-CoV-2: 2,618/11,940 [21.9%] vs No SARS-CoV-2: 16,482/1,960,213 [0.8%]; OR: 5.8 [5.5 – 6.1]; pConclusionsThe low incidence of SARS-CoV-2 infection in NHS surgical pathways suggests current infection prevention and control policies are highly effective. However, the high mortality amongst patients with SARS-CoV-2 suggests these precautions cannot be safely relaxed.Summary boxesWhat is already known on this topicHigh mortality rates have been reported amongst surgical patients who develop COVID-19 but we don’t know how this compares to the concurrent surgical population unaffected by COVID-19.Strict infection prevention and control procedures have substantially reduced the capacity of surgical treatment pathways in many hospitals.The very large backlog in delayed and cancelled surgical procedures is a growing public health concern.What this study addsFewer than 1 in 100 surgical patients are affected by COVID-19 in the English National Health Service.Elective surgical patients who do develop COVID-19 are 30 times more likely to die while in hospital.Infection prevention and control procedures in NHS surgical pathways are highly effective but cannot be safely relaxed.

Summary Background Prominent ears are the most common congenital abnormality of the head and neck, occurring in 5% of the Caucasian population. Facial disfigurement can cause psychosocial distress, low self-esteem and varying levels of social isolation most notable in school-age children. Although prominent ear correction is the most frequently performed aesthetic operation in children and adolescents, to our knowledge, the relationship between prominent ears and psychological, social and educational issues has not been systematically assessed. Purpose of study To investigate the psychological, social and educational impact of prominent ears and to examine how prominent ear correction affects health-related quality of life (HRQoL). Methods A systematic review was conducted using a protocol registered with PROSPERO and in line with the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses statement. A comprehensive search of the literature was conducted using MEDLINE, EMBASE, PyscINFO, HMIC Health Management Information Consortium, Ovid Journals Database, NHS Wales Full-Text Journals and The Cochrane Database. The inclusion criteria stated that any study investigating the association between psychological, social or educational issues, or HRQoL and prominent ears or otoplasty should be incorporated. All studies were reviewed by two authors, with data extracted for the studies finally included. Findings Fourteen articles were finally included, with a total of 786 patients. Thirteen out of 14 papers analysed the post-operative effect of surgical correction of prominent ears. The most common motivating factor for surgery was bullying, with young males of school age being the worst affected. Prominent ear patients report higher levels of bullying and social problems, and lower levels of physical activity than patients with more severe facial disfigurements. Every study that assessed the psychosocial impact of surgery on prominent ears found a significant benefit to HRQoL. Conclusion and relevance Prominent ears pose severe psychological and social issues that should not be underestimated. Surgical correction has consistently been shown to significantly improve HRQoL.

Cellulose nanowhisker (NWC) was extracted by hydrolysing Pennisetum purpureum (PP) fibres with acid and alkali. They were subjected to different periods of acid hydrolysis; 30, 45, and 60 min. NWC morphology and physicochemical properties were characterised by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), particle size analyser, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis. NWC3, which underwent the longest hydrolysis time, showed the smallest width and length, under TEM. All samples presented a needle-like shape under TEM and AFM; uneven lengths and irregular shapes under FESEM; and a broad range of distribution, with the particle size analyser. All samples exhibited a good crystallinity index (CrI)—72.0 to 74.6%. The highest CrI% corresponded to 60 min of acid hydrolysis. Thermogravimetric analysis showed thermal stability between 310.72 °C and 336.28 °C. Thus, cellulose nanowhisker from PP fibres, have high potential as bio-nanocomposites.

Background Seizure recurrence after a fit has implications for both individuals and healthcare providers guiding neurologic prognosis, treatment, and driving and work restrictions. A systematic review of long-term seizure recurrence after eclampsia will help to quantify recurrence risk in this setting. Objective To evaluate the long-term recurrence of seizures after eclampsia. Search strategy After PROSPERO registration, Medline (Ovid), Embase, and Cochrane Library were searched by using the terms (eclampsia OR eclamp* OR eclamptic seizure* OR eclamptic fit*) AND (recur* OR recurrent fit* OR recurrent seizure*) for studies published up until December 2019. Selection criteria Studies describing long-term seizure recurrence after a diagnosis of eclampsia were included. Data collection and analysis Data were extracted from studies independently by two authors. Pooled prevalence was calculated and weighted based on sample size with a 95% confidence interval (CI). Main results Initially, 1754 unique studies were identified and 4 were included in the final analysis. The studies involved 1896 women, of whom 7 (0.37%) were affected by a further seizure. The weighted pooled prevalence of seizure recurrence was 0.18% (95% CI, 0.03-1.02). Conclusion The absolute rate of long-term seizure recurrence after eclampsia is extremely low and within safe limits for driving.

A dynamic mechanical analysis was undertaken to determine the influence of moisture on the mechanical properties of interwoven hemp/polyethylene terephthalate (PET) hybrid composites. Composite laminates were fabricated using vacuum infusion process; form epoxy resin reinforced with interwoven hemp and PET fibres. Woven hemp, woven PET, and interwoven hemp/PET hybrid composites were produced. The hybrid hemp/PET composites yielded the highest final residue % due to the PET fibres which improved the thermal stability. The glass transition temperatures of the woven hemp, woven PET, and interwoven hemp/PET hybrid composites were 68, 67, and 69 °C, respectively. Water absorption tests were conducted, and tensile and flexural tests were conducted on the wet and dry specimens. The water uptake of the hemp/PET hybrid composite was half that of the woven hemp composites. The tensile and flexural strengths of the interwoven hemp/PET hybrid composites were 4% and 22% greater than those of the woven hemp composites, respectively.

An automated multiaxial cyclic loading pressure testing rig was developed as an alternative to the existing short-term test procedure specified by ISO 14692 and ASTM D2992. Conventionally, 14 months are required to estimate the residual properties at the end of expected life (20–50 years). The test periods and costs associated with this long-term test are high. To resolve this, a novel rig was developed based on the ultimate elastic wall stress (UEWS) algorithm, allowing five multiaxial stress ratios to be tested. The test involved the cyclic pressurizing of the pipe with 1-min of pressure and 1-min of zero pressure. The test rig was tested under five stress ratios using glass-epoxy composite pipes with winding angles of [±45°]4, [±55°]4 and [±63°]4. The rig is capable of testing both static and cyclic pressure loading, thereby reducing the test period and related costs. The results provide a more realistic failure envelope.

Summary The structural performance of polymer composites reinforced with plant fibres when exposed to fire was experimentally evaluated and compared against an E-glass fibre laminate. Fire testing under combined one-sided radiant heating and static tensile loading revealed that flax, jute, or hemp fibre composites experience more rapid thermal softening and fail within much shorter times than the fibreglass laminate, which is indicative of vastly inferior structural performance in fire. The plant fibre composites soften and fail before the onset of thermal decomposition of the plant fibres and polymer matrix, whereas the E-glass fibres provide the composite with superior tensile properties to higher temperatures and higher applied tensile stresses. The tensile performance of the three types of plant fibre composites in fire was not identical. When exposed to the same radiant heat flux, the flax fibre composite could withstand higher tensile stresses for longer times than the hemp and jute laminates, which showed similar performance.

The absorption behaviour of water and its effect on the tensile and flexural properties of interwoven cellulosic fibres were investigated. Hybrid composites consisting of interwoven kenaf/jute and kenaf/hemp yarns were prepared by an infusion process that used epoxy as the polymer matrix. The water absorption characteristics of the fibres were obtained by immersing the composite samples in tap water at room temperature, until reaching their water content saturation point. The dry and water-immersed woven and interwoven hybrid composite samples were subjected to tensile and flexural tests. To study the effect of water penetration in the fibre/matrix interface, fractured samples were examined using field emission scanning electron microscopy (FESEM). The study shows that the mechanical and water-resistant properties of the kenaf, jute, and hemp fibres were improved through hybridization. However, as a result of water penetrating the fibre/matrix interface, longer water-immersion times reduced the tensile and flexural strength of the composites.

In this study, the fire structural properties of a basalt fibre reinforced polymer laminate under compressive loading were investigated analytically and experimentally, and compared against an E-glass fibre composite with the same fibre content, ply orientation and polymer matrix. A thermal-mechanical model was used to compute the softening rate and failure stress of basalt fibre laminates which collapse, when loaded in compression, by either global buckling or material failure when exposed to fire. Fire structural measurements involving one-sided radiant heating with axial compressive loading were also performed. The measurements revealed that the softening behaviour and failure stress of the basalt fibre laminate were inferior to those of the glass fibre composite. Furthermore, the fire reaction properties, such as heat release rate and smoke density, were also less favourable for the basalt laminate. This appears to be mainly due to the thermal absorptivity of the basalt fibre laminate being higher, which causes it to heat up at a faster rate and reach higher temperatures when exposed to a radiant heat flux.

Facial skin cancer is common, and its treatment affects patient's health-related quality of life (HRQoL), as demonstrated by patient-reported outcome measures (PROMs). In this study, we anglicise and validate the novel FACE-Q Skin Cancer Module for the UK population. Anglicisation of the FACE-Q Skin Cancer Module followed international guidance for cross-cultural adaptation. Cognitive interviews were performed, producing a reconciled and harmonised version for validation. Patients undergoing facial skin cancer excision were prospectively recruited and asked to complete the anglicised FACE-Q Skin Cancer Module, along with the Skin Cancer Index (SCI) and European Quality of Life-Five Dimensions (ED-5D) questionnaire, pre-operatively and 6-8 weeks post-operatively. Data were analysed using classical test theory. Ethical approval was obtained (REC: 16/WM/0445). One hundred and ten patients were recruited between August 2017 and July 2018. Internal consistency was high (Cronbach's alpha 0.867-0.967). All subscales had a single-factor solution using principal component analysis. Construct validity, as measured between the FACE-Q subscales and SCI subscales, was good, with >75% of a priori predictions confirmed. Pearson's r for item-total correlation was >0.80 for several items, and significant ceiling effects are shown in 7 of the 10 subscales, suggesting some item redundancy. The UK version of this well-designed PROM demonstrates good face and construct validity. There is however a degree of redundancy within the scales, and further work using Rasch analysis on a larger sample will help address this.

The effects of hydrothermal ageing on the crushing behaviour of glass fibre-reinforced epoxy (GRE) pipes are discussed. Pipes with three different winding angles (±45°, ±55°, ±63°) were manufactured by filament winding process. The pipes were then hydrothermally aged in tap water at a constant temperature of 80 °C for periods of 500, 1000, and 1500 h. Uniaxial compressive tests were conducted on the virgin and aged samples using a universal testing machine in accordance with ASTM D695 -10. The tests were also performed at temperatures ranging from room temperature (RT) at 25 °C to 45 °C and 65 °C to study the response of the pipes at elevated temperatures. Scanning electron microscopy (SEM) images were captured and the relationship between the ageing period and strength of the GRE pipes was determined. The results indicate that the strength of the GRE pipes significantly decreases with increase in the temperature and ageing period. On the contrary, the strength increases as the winding angles decrease. The compressive strength of the pipes was also predicted using a Berbinau’s based model and was found to correlate well with the earlier obtained experimental results yielding a maximum variation of less than ∼25%.

The thermal behaviour and dynamic mechanical analysis of Pennisetum purpureum/glass-reinforced hybrid composites were investigated. Hybrid composite laminates were fabricated using untreated, 5%, or 10% alkali-treated P. purpureum fibres with woven E-glass fibres and epoxy resin. The composites were manufactured using a vacuum infusion process; the volume fractions of the P. purpureum, glass fibre, and epoxy resin were 24%, 6%, and 70%, respectively. Thermogravimetric analysis (TGA) demonstrated that the amount of residue of the hybrid composites decreased as the concentration of the alkali used to treat the P. purpureum fibres increased. The glass transition temperature values of the neat epoxy, and hybrid composites with the untreated, 5%, and 10% alkali-treated P. purpureum fibres were 64, 64, 67, and 63 °C, respectively as determined by dynamic mechanical analysis (DMA). When tested at room temperature (RT), the maximum tensile and flexural strengths were recorded for the hybrid composites with the 5% alkali-treated P. purpureum fibres. At >60 °C, as the temperature approached Tg, debonding of the fibre and matrix occurred, which resulted in a reduction of the tensile and flexural strengths. The fractured surface morphologies of the samples indicated that improved fibre–matrix interfacial bonding was achieved for the 5% alkali-treated P. purpureum/glass hybrid composites.

The effects of accelerated hydrothermal ageing on the behaviour of composite tubes under multiaxial stress were experimentally investigated. A set of [±55°] 4 tubes were hydrothermally aged at 80 °C for 1500 h. An indigenous automated test rig was fabricated to accommodate five stress ratios—0H:1A, 1H:1A, 2H:1A, 4H:1A, and 1H:0A. The cyclic test involved, pressurising the tube with 1-min pressure and 1-min no-pressure cycles. The first ply failure points were determined from the axial and hoop stresses. Failure envelopes were constructed at the aforesaid five stress ratios. Fourier transform infrared results show an increase in the intensity of absorbance peaks of the OH stretching bands at the interphase. The scanning electron microscopy micrographs of aged samples show clear debonding between the epoxy resin and the glass fibres, which is a cause of failure. Moisture uptake by the epoxy leads to matrix osmotic cracking, resulting in damage.

This study proposes a novel approach to determine the fibre volume fraction in composites using vibration based non-destructive technique with a neural network. Currently, the volume fraction of a glass fibre/matrix based composite material is assessed using destructive techniques. Instead of changing or destroying the structure, a new non-destructive approach based on vibration analysis is proposed. Complete experimental protocols were developed to capture the vibration pattern. An auto-regressive model was developed as a feature extraction tool to classify the fibre volume fractions and as a pole tracking algorithm. The classification performances were within the range of 90–98%. For NDT method to be efficient, the classification results were then compared with destructive burn-out technique. The results of non-destructive test showed good agreement with those obtained through destructive test suggesting that the proposed method is an alternative to ASTM D2584-11 for determining the volume fraction of a glass fibre/matrix composite.

The effect of moisture absorption on untreated and alkaline-treated Napier grass fibre-reinforced polyester composites was evaluated. Under room-temperature immersion, the water absorption behaviour of the Napier grass fibre composites conformed to the Fickian diffusion mechanism. Compared with the untreated fibres, the treated fibres absorbed less water due to the removal of lignin and hemicelluloses. The tensile and flexural strength of the Napier grass composites decreased with increased water absorption. SEM analysis showed that the treated Napier grass fibre composites contained fewer fibre pull-outs and splits compared with the untreated composites, which supports the improved performance.

The effect of moisture absorption on the mechanical degradation of hybrid Pennisetum purpureum /glass–epoxy composites was investigated. The hybrid P. purpureum /glass–epoxy composites plates were manufactured by the vacuum infusion method using epoxy resin as a matrix. Following 50 h of water immersion, the hybrid composite specimens were tested. The moisture content reduced as the glass fibre content increased. The wet and dry hybrid composite specimens were subjected to tensile and flexural tests. The incorporation of the glass fibre into the P. purpureum –epoxy composites enhanced their tensile and flexural strength, as well as their modulus. The tensile and flexural strengths of the hybrid P. purpureum /glass–epoxy composites (24/6–70 vol%) were 43 and 60 MPa, respectively. However, the tensile and flexural properties significantly degraded under wet conditions. Using field emission scanning electron microscopy (FESEM), morphological analysis was performed to observe the fracture behaviour of the specimens and the effect of water molecules.

A multi-layer polymer metal laminate (PML) system is described, which can be used to thermally insulate lightweight structural materials, such as aluminium or carbon fibre reinforced plastic (CFRP) composite, when exposed to fire. The system comprises many thin adhesively-bonded metal foils, bonded directly to the structural substrate. When exposed to fire the PML adhesive thermally decomposes with the generation of volatiles, causing the foils to delaminate and inflate, thus greatly reducing its thermal conductivity. The expanded PML slows heat transfer from the fire into the structural substrate, resulting in lower temperatures and increased structural survivability. The fire protection effects of two different thicknesses of PML are demonstrated here for both aluminium and CFRP substrates. Fire exposure tests demonstrate that the substrate temperatures are reduced and the time to failure under load is substantially improved. The protection offered is equivalent or superior to conventional fire protection materials such as ceramic fibre mat or intumescent coatings. The advantage of the PML is that, in non-fire conditions, it contributes to the appearance and load-bearing capability of the structure without being prone to damage or water absorption. Keywords: Fire protection, Multi-layer laminate, Composites, CFRP, Aluminium, Structural survivability

The effects of Napier filler on the compressive properties of an unsaturated polyester polymer were studied at various temperatures. Polyester resins with Napier filler contents of 1, 3 and 5wt-% were prepared using three different mixing methods (hand mixing, water shaker bath and hot plate stirrer). Static uniaxial compression tests were conducted to investigate the compressive stress–strain response, failure mechanisms and damage characteristics of the neat and Napier filled polyester. The results show that the elastic modulus and compressive strength of the Napier modified polyesters were improved, without significantly reducing the failure strain, by increasing the Napier content. The samples prepared by the hot plate stirrer method yielded the highest compressive strength. The strength and Young's modulus of the Napier filled polyester decreased as the temperature increased. This result suggests that the Napier filler introduced additional mechanisms of energy absorption, improving the compressive p...

The mechanical properties of Napier grass fibre-reinforced composites were characterised. Napier grass fibres were extracted through water retting process. The effect of alkali-treatment on the tensile properties and morphology of the fibres was investigated. The fibres were alkali-treated using NaOH solutions of various concentrations and subjected to single fibre testing. The morphology of the fibres was observed using scanning electron microscopy. The 10% alkali-treated Napier grass fibres yielded the highest strength. To fabricate the polymer composites, Napier grass fibre and polyester resin were used as the reinforcing material and polymer matrix, respectively. The tensile and flexural properties of the composites were studied. In general, up to a certain threshold value, the tensile and flexural strengths of the composites increased as the fibre volume fractions increased, following which, there was a reduction in strength. The maximum tensile and flexural strengths of the composites were obtained at 25% fibre loading.

The design of composite repairs of corroded oil and gas pipelines must take into account the strength of the interface adhesion between composite and metal. A shaft-loaded blister test is a common method to measure interface fracture toughness and energy release rate. The study aimed on evaluating shaft-loaded blister tests as replacements for more complex pressure blister tests. Specimens investigated were thick fibre-reinforced plates bonded on metal disks as substrates containing a circular through-hole defect. This paper presents the influence of different punch head geometries on the resulting energy release rates and compares the results with blister tests using fluid pressure. Test and simulation results are presented and analytical solutions were derived and evaluated to establish best fitting formulations. It was shown, that significant variations between the different means of loading exist.

Pennisetum purpureum (PP) fibres were comprehensively characterised to assess their potential as reinforcing materials in polymer composites. The fibres were treated with 5, 7, 10, 12, and 15% sodium hydroxide wt.% concentration for 24 h. The fibres were subjected to single fibre tensile tests, thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The average diameter of the untreated fibres was 0.24 ± 0.02 mm, and the treated fibres had an average diameter of less than 0.21 ± 0.03 mm, yielding a 12–45% reduction in the diameter. The moisture content of the treated fibres decreased as the concentration of the alkali increased. The morphological observation demonstrated that as the alkali concentration increased, the fibre becomes more compressed due to collapse the cellular/lumen structure, the void content decreased, and its surface became rougher. The 5% alkali-treated fibre achieved an average maximum ultimate tensile stress of 141 ± 24 MPa. Young's modulus on the other hand, decreased from an average of 5.68 ± 0.14 GPa for untreated fibre to only 0.55 ± 0.17 GPa as the alkali concentrations increased from 5 to 15%. Keywords: Pennisetum purpureum fibre, Mechanical properties, Infrared spectroscopy, Thermogravimetric analysis, Natural fibre

This study investigated the effects of water ageing and low-velocity impact loadings on E-glass fibre/epoxy composite pipes subjected to monotonic internal pressure. The pipes, which consisted of six antisymmetric layers with (±55°)3 winding angles, were manufactured by the filament winding process. The specimens were cut from the pipes to the required test length. The specimens were then subjected to the ageing process by being immersed in 80 °C tap water for time intervals of 500, 1000, and 1500 h. Impact loadings of three different energy levels (5 J, 7.5 J, and 10 J) were applied, which were followed by monotonic burst tests. Scanning electron microscopy images were captured and the correlation between the ageing time and the level of impact energy on the pipes' burst strength was identified. The results indicated that the peak force and displacement increased as the impact energy increased. The monotonic burst test results revealed that the specimens that had been aged and were impacted by higher energy yielded lower burst strength. Weepage and eruption failures were observed depending on the applied impact energies. Keywords: Filament winding, GRE composite pipe, Ageing, Impact loading, Monotonic burst test

The effects of winding angle on the behaviour of glass/epoxy composite tubes under multiaxial cyclic loading were investigated. The performance of such composite tubes was studied using an indigenous automated test procedure that is compatible with the internal qualification requirements of the composite pipe manufacturers. Glass fibre reinforced epoxy (GRE) composite pipes with three winding angles, namely, [±45°]4, [±55°]4, and [±63°]4, were tested. A novel automated test rig was fabricated to accommodate five stress ratios, ranging from pure axial to pure hoop loadings. The cyclic pressure test was conducted until droplets of water were seen on the outer surface of the pipe. Failure envelopes were then constructed based on the first ply failure (FPF) points determined from the axial stress to hoop strain response at five stress ratios. Three functional failure modes, namely, tensile axial, weepage, and local leakage failures, were observed during the tests. The results indicate that each winding angle dominates a different optimum pressure loading condition, namely, [±55°]4 for pure hydrostatic loading, [±45°]4 for hoop to axial loading, and [±63°]4 for quad hoop to axial loading. The envelopes show a strong dependence on the stress ratio and winding angle. Keywords: Glass fibre reinforced epoxy (GRE), Ultimate Elastic Wall Stress (UEWS), First ply failure (FPF), Multiaxial stress ratio, Cyclic loading

Background Facial scarring can have a dramatic effect on a patient's psychological health and wellbeing and present unique management challenges. This patient population remains poorly characterised in the contemporary literature. Aims To evaluate the prevalence of, and risk factors associated with affective disorders in adult patients with facial scars. Methods A systematic review was conducted using a protocol registered with PROSPERO and in line with the PRISMA statement. A comprehensive search of the literature was conducted using PubMed, MEDLINE, EMBASE, PSYCHInfo and The Cochrane Library. Results Twenty one studies were included, with a total of 2,394 participants. Using a random effects model, the weighted pooled prevalence of anxiety was 26.1% (95% CI 17.9%-36.3%) and the weighted pooled prevalence of depression was 21.4% (95% CI 15.4%-29.0%). Studies identified female gender, past psychiatric history and violent causation as factors associated with anxiety and depression. Limitations Included studies were limited to those published in peer reviewed journals. Longitudinal trends in both anxiety and depression were limited by a short duration of follow up. Conclusions There is a high and persistent burden of affective disorders in patients with facial scars. Additional research is required to further characterise this population and develop effective management strategies.

The in vitro degradation and mechanical properties of a 3D porous Pennisetum purpureum (PP)/polylactic acid (PLA)-based scaffold were investigated. In this study, composite scaffolds with PP to PLA ratios of 0%, 10%, 20%, and 30% were immersed in a PBS solution at 37°C for 40 days. Compression tests were conducted to evaluate the compressive strength and modulus of the scaffolds, according to ASTM F451-95. The compression strength of the scaffolds was found to increase from 1.94 to 9.32MPa, while the compressive modulus increased from 1.73 to 5.25MPa as the fillers' content increased from 0wt% to 30wt%. Moreover, field emission scanning electron microscopy (FESEM) and X-ray diffraction were employed to observe and analyse the microstructure and fibre-matrix interface. Interestingly, the degradation rate was reduced for the PLA/PP20 scaffold, though insignificantly, this could be attributed to the improved mechanical properties and stronger fibre-matrix interface. Microstructure changes after degradation were observed using FESEM. The FESEM results indicated that a strong fibre-matrix interface was formed in the PLA/PP20 scaffold, which reflected the addition of P. purpureum into PLA decreasing the degradation rate compared to in pure PLA scaffolds. The results suggest that the P. purpureum/PLA scaffold degradation rate can be altered and controlled to meet requirements imposed by a given tissue engineering application.

Analytical models have been evaluated for chitosan nanocomposites reinforced by needle-like hydroxyapatite (HA) and globule-like polyhedral oligomeric silsesquioxane (POSS) particles. The particle elastic stress distribution was investigated for the case of high loads with the matrix deforming plastically and the particle pull-out energy during matrix crack propagation was modelled. Model predictions, over a range of reasonable interfacial shear stress values and particle aspect ratios, show contrasting behaviour between the two types of nanoreinforcement. In HA particles, the axial stress is distributed fairly uniformly, whereas, with POSS it is concentrated towards the centre of the particle. The radial stress at the HA particle surface was found to be uniformly distributed, whereas in POSS it increased non-linearly to a high (theoretically infinite) value with distance from the particle centre to the end. For particles bridging a travelling matrix crack, the model predicts that the pull-out energy dens...

This paper presents the stress–strain response and general lifetime damage modelling of glass fibre reinforced epoxy (GRE) composite pipes subjected to multi-ratios stress loadings at room temperature (RT). This particular modelling work was developed to predict the non-linear stress– strain response caused by the fatigue static and cyclic loading in the multiaxial ultimate elastic wall stress (UEWS) tests by considering the effects of matrix cracking within the laminates. Although the UEWS procedure is not a standard protocol used for qualification of GRE pipes, it appears to offer an option to existing procedures delineated in ASTM D2992. The ply properties initially expressed as a function of crack density was computed as a function of increasing stress and strain using shear lag approximation. In general lifetime damage model, the effects of stress developed in each ply from ultimate elastic wall stress (UEWS) test were expressed in a single quadratic term of axial and hoop stress. The term then solved to produce limits with respect to axial and hoop stress, which represented in a graphical form of failure envelope. The predictions from both models are found to be in good agreement with the data from the multiaxial UEWS tests of i55u filament wound GRE pipes. These models thus enable for the long term performance prediction of the pipes under combined loadings.

This paper describes the acoustic emission (AE) monitoring of multiaxial ultimate elastic wall stress (UEWS) tests of filament wound glass fibre-reinforced epoxy composite pipes under hydrostatic, pure axial and pure hoop loadings at room temperature. The purpose of AE monitoring is to quantitatively identify and characterise damage inception and evolution, which leading to different failure mechanisms via an analysis of AE parameters. AE parameters such as counts and energy released were plotted against time, and changes of these AE activities were monitored. A 3D correlation plot between AE amplitude and duration against time for each loading condition was produced and analysed. The AE measurement of both hydrostatic and pure axial loading suggested that matrix cracks were initiated early in the tests and possible had progressed into delamination failure just before UEWS point was reached at 200 MPa of hoop stress and 63 MPa of axial stress, respectively. No clear damage initiation and progression was o...

This paper presents the modelling of a general lifetime performance for glass fibre reinforced epoxy (GRE) composite pipes similar to the well-known Tsai-Hill interactive failure criterion. Tsai Hill criterion is based on the Von Misses distortional energy criterion which was modified to satisfy the orthotropic nature of GRE composite pipes. The effects of stress developed in each ply from ultimate elastic wall stress (UEWS) test were expressed in a single quadratic term of axial and hoop stress through laminate theory. The term then solved to produce limits with respect to axial and hoop stress, which represented in a graphical form of failure envelope. The modelled envelop shows a good agreement with experimental data from the multiaxial UEWS test of ±55° GRE composite pipes. This indicates that such model can be used to predict the long-term performance of GRE pipes under combine loadings.

One of the typical failure modes of composite repairs in oil and gas pipelines is the formation of a blister underneath the repair. Exceeding the critical pressure, and therefore the critical energy release rate ( GC) for crack propagation, will result in failure of the repair. Knowing the magnitude of the energy release rate ( G) is therefore key to understanding the interfacial debonding between a steel pipe and a composite repair. This paper describes two approaches for calculating the value of G for crack advance: (a) a purely analytical evaluation and (b) finite element analysis computation using the pressure–volume method (PVM). The design guidance by ASME and ISO standards for correct dimensioning is also presented, incorporating the most recent changes, which are derived from the work presented here.