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Background Although healthcare worker (HCW) absenteeism due to COVID-19 exposure represents a significant challenge, there are currently no evidence-based criteria for assessing infection risk based on COVID-19 exposure type. We aimed to identify the incidence of acquiring infection following varying exposures to COVID-19 to guide safe return-to-work policies for staff in healthcare settings. Methods We analyzed prospectively collected data at an academic centre with approximately 17 000 active staff between January 1 - April 30, 2022 during a large BA.1 Omicron surge. More than 99% of staff received >2 vaccine doses. All staff self-reporting household, community, and workplace exposure to confirmed cases of COVID-19 submitted attestation to the Occupational Health department detailing the nature of the exposure, the duration, and setting. Staff were required to report all positive test results by rapid antigen or PCR testing. Results A total of 3209 staff submitted exposure reports (2493 household, 539 community, and 177 workplace). Of these, 1008 (31.4%) tested positive 2 days prior to or 14 days after the exposure (36% household; 19% community, 7% workplace). In the community exposure group, 19% tested positive due to a discrete exposure of < 4 hours and 21% tested positive with an exposure >4 hours. For household exposures and workplace exposures, these values were 25%/27% and 6%/10%, respectively (Figure 1). The median time to testing positive was 2 days for household exposures and 3 days for community and workplace exposures (Figure 2, Panels A-C). By day 4 post-exposure, more than 80% of positive results were reported (Figure 2, Panel D). Risk of testing positive differed based on baseline symptom status at the time of reporting (Table 1). Risk of infection during the peri-exposure period (2 days before reported exposure and 14 days after) according to type and duration of exposure. Background rate of infection based on regional incidence of disease due to BA.1 Omicron wave. SARS-CoV-2 Infection Risk (A - household; B - Community; C - Workplace) after exposure. Time to infection in all groups is shown in panel D. The risk of infection amongst healthcare workers reporting exposures, according to their symptom status at the time of reporting their exposures. Conclusion Our data suggests that the highest risk of acquiring SARS-CoV-2 was via household contacts, regardless of exposure duration, with workplace exposures carrying less risk. Using a cut-off of 4 hours for exposure duration to delineate risk may be of limited value. These data could help workplaces predict infection risk following exposure and guide return-to-work policies that balance the need to staff workplaces, including hospitals, with reducing risk of on-site transmission during periods of increased community transmission (Figure 3). Risk of Infection in the Context of Background Infection Background general population infection risk based on regional incidence of disease due to BA.1 Omicron wave. Disclosures All Authors: No reported disclosures.

Objective: Extracorporeal membrane oxygenation (ECMO) has been widely used in the care of patients with respiratory failure from coronavirus disease 2019 (COVID-19). We characterized bloodstream infections (BSIs) and ventilator-associated pneumonias (VAPs) in COVID-19 patients supported with ECMO, and we investigated their impact on patient outcomes. Design: Retrospective cohort study from March 1, 2020, to June 30, 2021. Setting: Academic tertiary-care referral center. Patients: Consecutive adult patients admitted for COVID-19 who received ECMO. Methods: We identified BSIs and VAPs and described their epidemiology and microbiology. Cumulative antimicrobial use and the specific management of BSIs were determined. Multivariate time-dependent Cox proportional hazards models were constructed to evaluate the impact of BSIs and VAPs on mortality, controlling for age, receipt of COVID-19–specific therapeutics, and new renal replacement therapy. Results: We identified 136 patients who received ECMO for COVID-19 pneumonia during the study period. BSIs and VAPs occurred in 81 patients (59.6%) and 93 patients (68.4%), respectively. The incidence of BSIs was 29.5 per 1,000 ECMO days and increased with duration of ECMO cannulation. Enterococci, Enterobacterales, and Staphylococcus aureus were the most common causes of BSIs, whereas S. aureus, Klebsiella species, and Pseudomonas aeruginosa comprised the majority of VAPs. Mean antibiotic use comprised 1,031 days of therapy per 1,000 ECMO days (SD, 496). We did not detect an association between BSIs or VAPs and mortality. Conclusions: BSIs and VAPs are common in COVID-19 ECMO-supported patients. Efforts to optimize their diagnosis, prevention, and management should be prioritized.

To assess the effects of faecal microbial transplant (FMT) from lean people to subjects with obesity via colonoscopy.In a double-blind, randomized controlled trial, subjects with a body mass index ≥ 35 kg/mIn the allogenic versus autologous groups, HOMA-IR and clinical variables did not change significantly, but IM and metabolites changed favourably (P 0.05): at 1 month, Coprococcus, Bifidobacterium, Bacteroides and Roseburia increased, and Streptococcus decreased; at 3 months, Bacteroides and Blautia increased. Several species also changed significantly. For metabolites, at 1 month, serum kynurenine decreased and faecal indole acetic acid and butenylcarnitine increased, while at 3 months, serum isoleucine, leucine, decenoylcarnitine and faecal phenylacetic acid decreased. Metagenomic pathway representations and network analyses assessing relationships with clinical variables, metabolites and IM were significantly enhanced in the allogenic versus autologous groups. LDL and appetite measures improved in the allogenic (P 0.05) but not in the autologous group.Overall, in those with obeisty, allogenic FMT via colonoscopy induced favourable changes in IM, metabolites, pathway representations and networks even though other metabolic variables did not change. LDL and appetite variables may also benefit.

Traditional statistical as well as artificial intelligence techniques are widely used for stock market forecasting. Due to the nonlinearity in stock data, a model developed using the traditional or a single intelligent technique may not accurately forecast results. Therefore, there is a need to develop a hybridization of intelligent techniques for an effective predictive model. In this study, we propose an intelligent forecasting method based on a hybrid of an Artificial Neural Network (ANN) and a Genetic Algorithm (GA) and uses two US stock market indices, DOW30 and NASDAQ100, for forecasting. The data were partitioned into training, testing, and validation datasets. The model validation was done on the stock data of the COVID-19 period. The experimental findings obtained using the DOW30 and NASDAQ100 reveal that the accuracy of the GA and ANN hybrid model for the DOW30 and NASDAQ100 is greater than that of the single ANN (BPANN) technique, both in the short and long term.

The coronavirus disease 2019 (COVID-19) pandemic has placed significant burden on healthcare systems. We compared

To analyze the spread of a novel sequence type (ST1478) of vancomycin-resistant Enterococcus faecium across Canadian hospitals.Retrospective chart review of patients identified as having ST1478 VRE bloodstream infection.Canadian hospitals that participate in the Canadian Nosocomial Infection Surveillance Program (CNISP).From 2013 to 2018, VRE bloodstream isolates collected from participating CNISP hospitals were sent to the National Microbiology Laboratory (NML). ST1478 isolates were identified using multilocus sequence typing, and whole-genome sequencing was performed. Patient characteristics and location data were collected for patients with ST1478 bloodstream infection (BSI). The sequence and patient location information were used to generate clusters of infections and assess for intrahospital and interhospital spread.ST1478 VRE BSI occurred predominantly in a small number of hospitals in central and western Canada. Within these hospitals, infections were clustered on certain wards, and isolates often had20 single-nucleotide variants (SNV) differences from one another, suggesting a large component of intrahospital spread. Furthermore, some patients with bloodstream infections were identified as moving from one hospital to another, potentially having led to interhospital spread. Genomic analysis of all isolates revealed close relatedness between isolates at multiple different hospitals (20 SNV) not predicted from our epidemiologic data.Both intrahospital and regional interhospital spread have contributed to the emergence of VRE ST1478 infections across Canada. Whole-genome sequencing provides evidence of spread that might be missed with epidemiologic investigation alone.

Since the publication of our original paper in vol. 7, no. 6 of this journal [1], we have detected several misprints and errors that are corrected here, in the order in which they appear in the original paper.

With the gradual depletion of primary mineral sources, there is need of secondary recurring materials to carry out metal and mineral extractions. With due advancement in research, there is a huge amount of waste generating from variable resources and disposal of those waste material is creating an alarming situation. Vanadium need in India is met through imports only. The available ores and minerals consist of some negligible amount of vanadium, processing which is a costly affair. Keeping in view the above parameters, in the present study, an attempt has been made to extract vanadium from waste red mud, releasing from Aluminum industries. It has been observed that by using stoichiometric amount of alkali solution, with appropriate temperature and time, it is possible to extract about 98% of vanadium from red mud.

In the present scenario, increasing population has put a tremendous pressure on various environmental sources. Water bodies are getting polluted due to industrial discharges leading to life threatening diseases and contaminations. In the present study, an attempt has been made to monitor the impact of various industrial waste discharges in River Rushikulya and its impact on phosphorus contamination in the available water sources. In this process, agro based waste materials are being taken as the base material to treat the contaminated water. An efficient and stable absorbent has been prepared using rice husk and Coir Pith based activated material for phosphorus removal. In this Context, various combinations of absorbents are prepared and subjected to testing for their physical, chemical and mechanical parameters including stability and recycling. The data revealed that by using an absorbent prepared with 60% rice husk and 40% Coir Pith, it is possible to remove 95% of the phosphate from the contaminated water sources.

COVID-19 is a kind of virus of the Corona family originated from Wuhan, China, and spread over more than 215 countries in the world, more than 2.3 lakhs people died, and more than 32 lakhs are affected globally till date and numbers are continuously increasing. Because of this global pandemic, citizens of the country are in a panic situation. Sentiment Analysis (SA) is a prominent field to analyze data available on social media. This research work explores SA using the Lexicon-based approach to analyze the sentiment of six different countries: India, the USA, Spain, Italy, France, and the UK. Data from March 15 to April 15, 2020 extracted from Twitter and used to identify sentiment as Negative, Neutral, or Positive using Lexicon-based and Valence Aware Dictionary for Sentiment Reasoning (VADER)-based approaches. Empirical results show that negativity exists in almost all the countries because of COVID-19. Out of six countries considered for the SA, the UK has the highest negativity of 23.03%, followed by France with 22.71%, the USA with 22.01%, and India is having negativity of 18.39% using Simple Lexicon-based approach. At the same time, it is 35.92% in France, 35.68% in the UK, and 35.38% in the USA, while India has the least negativity of 31.03% based on the VADER-based approach. Both approaches are almost producing negativity in the same order with slight variations. Furthermore, a comparative detail analysis of India has also been done based on Twitter data. The data collected before and after lockdown using a simple Lexicon-based approach, and it has been observed that negativity is increasing after lockdown and slightly decreased during lockdown 2.0. Overall implication of this research work is that however negativity exists but people are more positive toward panic situation because of COVID-19 and also fighting against COVID-19 with restrictions like lockdown, home isolation, quarantine, limited access of resources, etc.

Forecasting about the Novel coronavirus disease 2019 (COVID-19) pandemic involves high uncertainty and may be affected by measures taken by the government to fight the disease. This research explores machine learning (ML) techniques to forecast the epidemiological trend of COVID-19 in India. We used 22 ML algorithms develop forecasting models and selected the four best ones on the basis of their performance using mean absolute percentage error (MAPE). Feature extraction and feature selection techniques were also employed to improve performance with cumulative and daily data obtained from Mar. 2 to Apr. 25, 2020. Because of the linear nature of cumulative data, the model built with these time series data outperforms with an MAPE of 0.498, 0.240, and 0.430, respectively, for cases that are confirmed or recovered and deaths using the extra tree regressor compared with the model built with daily data with an MAPE of 1.377, 1.302, and 0.488, respectively. Moreover, the study confirms that the models perform well at the validation stage with an MAPE of 4.123, 5.411, and 4.553, respectively, for confirmed or recovered cases and deaths using a model built with cumulative data and an MAPE of 6.261, 7.576, and 6.273, respectively, using a model built with daily data. On the basis of selected models, a 15-day forecast for confirmed and recovered cases and deaths from COVID-19 was performed that can be validated in the near future. However, it depends on precaution measures taken by the central and state governments as well as individuals, including social distancing, self-isolation from society, restrictions in bus, rail, and air transport, school, college, and market closings or openings, the extension of the lockdown period, privileges to be given during lockdown, and other measures, as well whether guidelines issued by government from time to time were followed.

Hakka Tulou are rammed earth buildings that have survived material aging, natural weathering and earthquakes for hundreds of years. Previous paper has reported our observations and findings from nondestructive evaluations in field with focus on the integrity of the rammed earth outer walls and inner timber structures as well as the thermal comfort of living in these buildings. This paper presents the structural response of Tulou buildings under earthquake loads using material data from field and employing finite element (FE) analysis program. The material characterization included scanning electron microscopy and compression strength/modulus of rammed earth samples and wall reinforcements, revealing their high strength and durability. The FE analyses were conducted on unreinforced Huanji Tulou as per the simplified lateral force analysis procedure defined by the Code ASCE-7 under three types of wall conditions: 1) unreinforced rammed earth outer wall only, 2) reinforced rammed earth outer wall without inner wooden structures, and 3) unreinforced rammed earth outer wall with inner wooden structures. The FE modeling revealed that the existing large crack in the outer earth wall of Huanji Tulou would not have developed under a strong earthquake load if the earth walls were reinforced. Furthermore, the high volume rammed earth wall integrated with inner timber structures would have offered the building unique earthquake resistance.

Since the publication of our original paper in vol. 7, no. 6 of this journal [1], we have detected several misprints and errors that are corrected here, in the order in which they appear in the original paper.

Excited states in $^{174}\mathrm{Re}$ have been populated in fusion-evaporation reactions at the Australian National University, and $\ensuremath{\gamma}$-ray spectroscopy has been used to determine the level structure and to deduce the underlying nucleon configurations. The half-life of the bandhead of the ${K}^{\ensuremath{\pi}}={8}^{\ensuremath{-}}$ band has been measured to be 2.7(4) ns. A band built on an isomeric state of spin-parity (${14}^{\ensuremath{-}}$) and a half-life of 53(5) ns has been observed here for the first time, and has been determined to have a four-quasiparticle structure. Contrasting reduced-hindrance values for its decay are discussed in terms of deformation and configuration changes, as indicated by configuration-constrained potential energy surface calculations.

The first-excited state g factor of 26 Mg has been measured relative to the g factor of the Mg 24 ( 2 1 + ) state using the high-velocity transient-field technique, giving g = + 0.86 ± 0.10 . This new measurement is in strong disagreement with the currently adopted value, but in agreement with the sd -shell model using the USDB interaction. The newly measured g factor, along with E ( 2 1 + ) and B ( E 2 ) systematics, signal the closure of the ν d 5 / 2 subshell at N = 14 . The possibility that precise g -factor measurements may indicate the onset of neutron pf admixtures in first-excited state even–even magnesium isotopes below 32 Mg is discussed and the importance of precise excited-state g -factor measurements on sd shell nuclei with N ≠ Z to test shell-model wavefunctions is noted.

The objective was to compare postoperative urinary retention using the Babcock and Kelly clamps for retropubic midurethral sling (RPS) tensioning. This was a retrospective cohort of isolated RPS procedures from December 2010 through April 2016 by five fellowship-trained surgeons at two institutions. Slings were tensioned with a Babcock clamp by grasping a 3-mm midline fold of mesh (RPS-B) or a Kelly clamp as a spacer between the sling and suburethral tissue (RPS-K). Assessment of urinary retention included the primary outcome of postoperative catheterization and several secondary outcomes, including discharge home with a catheter, within 1 year of surgery. Analysis of covariance was used to compute the mean difference in duration of catheterization and log-binomial regression was used to calculate risk ratios (RR) and 95% confidence intervals (CI). We included 240 patients. The RPS-B group had a lower body mass index and was more likely to be menopausal, have had pelvic organ prolapse surgery, and have a lower maximum urethral closure pressure than the RPS-K group. The mean duration of catheterization was similar, as demonstrated by the crude (0.21 days [−0.30–0.71]) and BMI-adjusted (0.07 days [−0.41–0.55]) mean difference in duration of catheterization. The incidence of postoperative OAB symptoms was comparable between the groups (BMI-adjusted RR: 0.95 (0.80–1.1)), and the incidence of revision did not differ (p = 0.7). The Babcock and Kelly clamp tensioning techniques appear comparable, with a low incidence of prolonged postoperative catheterization. Most catheters were removed on the day of the surgery. It is reasonable to tension retropubic midurethral slings with either method.

Phishing E-mail is an unwanted E-mail, sent by the phishers to get the sensitive information like password, account number and credit card details from users. This research work emphasizes on constructing an ensemble Machine Learning (ML) based model to detect phishing E-mail with Remove-Replace Feature Selection Technique (RRFST). RRFST reduces features from original feature space by selecting a feature in random manner and removes it if accuracy is being unchanged or increased otherwise feature is being replaced to its original feature space. Classifiers were developed using two Decision Tree (DT) algorithms i.e. C4.5 and Classification and Regression Tree (CART) along with ensemble of these two as an efficient classification model with reduced feature subset obtained through RRFST. Empirical results indicate that proposed FST produces remarkable performance of 99.27% accuracy using ensemble of C4.5 and CART with only 11 features. Research outcome of proposed FST is also investigated with two existing FSTs: Info Gain (IG) and Gain Ratio (GR).

In this paper a maximum power point tracking (MPPT) design for a photovoltaic (PV) system using a hybrid optimization technique is proposed. For maximum power transfer, maximum harvestable power from a PV cell in a dynamically changing surrounding should be known. The proposed technique is compared with the conventional Perturb and Observe (P&O) technique. A comparative analysis of power-voltage and current-voltage characteristics of a PV cell with and without the MPPT module when connected to the grid was performed in SIMULINK, to demonstrate the increment in the efficiency of the PV module after using the MPPT module.

Opioid use, addiction, and overdose are a growing epidemic in the USA. Our objective was to determine whether the amount of opioid medication prescribed following gynecologic and pelvic reconstructive surgery is insufficient, adequate, or in excess. We hypothesized that we were overprescribing postoperative opioids. Participants who were at least 18 years old and underwent gynecologic and/or pelvic reconstructive surgery from April through August 2016 were eligible to participate. Routine practice for pain management is to prescribe 30 tablets of opioids for major procedures and ten to 15 tablets for minor procedures. At the 2-week postoperative visit, participants completed a questionnaire regarding the number of tablets prescribed and used, postoperative pain control, and relevant medical history. Fisher’s exact test was used to compare data. Sixty-five participants completed questionnaires. Half (49.1%) reported being prescribed more opioids than needed, while two (3.5%) felt the amount was less than needed. Though not significant, participants who underwent major surgeries were more likely to report being prescribed more than needed (53.5%) compared with participants who underwent minor surgeries (35.7%; p = 0.47). Though not significant, participants with anxiety were less likely to report being prescribed more tablets than needed compared with participants without anxiety (44.4% vs. 57.1%; p = 0.38). This was also true of participants with depression compared with those without (37.5% vs. 58.3%; p = 0.17), and those with chronic pain compared with those without (33.3% vs. 60.0%; p = 0.10). Our current opioid prescription practice for postoperative pain management may exceed what patients need.

Stellar carbon synthesis occurs exclusively via the $3\alpha$ process, in which three $\alpha$ particles fuse to form $^{12}$C in the excited Hoyle state, followed by electromagnetic decay to the ground state. The Hoyle state is above the $\alpha$ threshold, and the rate of stellar carbon production depends on the radiative width of this state. The radiative width cannot be measured directly, and must instead be deduced by combining three separately measured quantities. One of these quantities is the $E0$ decay branching ratio of the Hoyle state, and the current $10$\% uncertainty on the radiative width stems mainly from the uncertainty on this ratio. The $E0$ branching ratio was deduced from a series of pair conversion measurements of the $E0$ and $E2$ transitions depopulating the $0^+_2$ Hoyle state and $2^+_1$ state in $^{12}$C, respectively. The excited states were populated by the $^{12}$C$(p,p^\prime)$ reaction at 10.5 MeV beam energy, and the pairs were detected with the electron-positron pair spectrometer, Super-e, at the Australian National University. The deduced branching ratio required knowledge of the proton population of the two states, as well as the alignment of the $2^+_1$ state in the reaction. For this purpose, proton scattering and $\gamma$-ray angular distribution experiments were also performed. An $E0$ branching ratio of $\Gamma^{E0}_{\pi}/\Gamma=8.2(5)\times10^{-6}$ was deduced in the current work, and an adopted value of $\Gamma^{E0}_{\pi}/\Gamma=7.6(4)\times10^{-6}$ is recommended based on a weighted average of previous literature values and the new result. The new recommended value for the $E0$ branching ratio is about 14% larger than the previous adopted value of $\Gamma^{E0}_{\pi}/\Gamma=6.7(6)\times10^{-6}$, while the uncertainty has been reduced from 9% to 5%., Comment: Accepted for publication as a Regular Article in Phys. Rev. C on July 29 2020

The aim of this study was to demonstrate a proof-of-concept approach to rectopexy that would provide the durability of the transabdominal procedure through use of sacral rectopexy with the decreased morbidity of a perineal procedure. This was done by utilizing a transvaginal approach and developing the rectovaginal space to accommodate sacral rectopexy placement using the FlexA fresh female cadaver was acquired and placed in the high lithotomy position. The rectovaginal space was developed to accommodate the trocar of the Flex robot using blunt and sharp dissection between the posterior vaginal wall and anterior rectum. A piece of mesh was introduced into the space and using an endoscopic tacker, which was secured to the sacral promontory. The mesh was secured to the anterior rectal wall using interrupted vicryl sutures. The purse string suture was removed and the rectovaginal orifice was closed using a running vicryl suture. At the completion of the procedure, a low midline laparotomy was conducted to verify anchoring of the mesh appropriately at the sacral promontory.This proof-of-concept protocol is the first description of the FlexThis proof-of-concept approach demonstrates that transvaginal rectopexy using the Flex

Garrett et al. systematically investigated band-crossing frequencies resulting from the rotational alignment of the first pair of i13/2 neutrons (AB) in rare-earth nuclei. In that study, evidence was found for an odd-even neutron number dependence attributed to changes in the strength of neutron pairing correlations. The present paper carries out a similar investigation at higher rotational frequencies for the second pair of aligning i13/2 neutrons (BC). Again, a systematic difference in band-crossing frequencies is observed between odd-N and even-N Er, Yb, Hf, and W nuclei, but in the BC case, it is opposite to the AB neutron-number dependence. These results are discussed in terms of a reduction of neutron pairing correlations at high rotational frequencies and of the effects of Pauli blocking on the pairing field by higher-seniority configurations. Also playing a significant role are the changes in deformation with proton and neutron numbers, the changes in location of single-particle orbitals as a function of quadrupole deformation, and the position of the Fermi surface with regard to the various ω components of the neutron i13/2 shell.

The yields of 42 projectile-like fragments (PLFs) and fission fragments and 36 target-like fragments (TLFs) were measured using off-line $\ensuremath{\gamma}$-ray spectroscopy in a thin target experiment involving the $^{136}\mathrm{Xe}+^{198}\mathrm{Pt}$ reaction. The center of target beam energy was 760.5 MeV $({\mathrm{E}}_{\mathrm{c}.\mathrm{m}.}=450$ MeV). The reported yields are compared with those from previous measurements for this reaction and with predictions of the GRAZING, di-nuclear systems (DNS), and improved quantum molecular dynamics (ImQMD) models. The yields of the TLFs and PLFs are, in general, substantially smaller than those previously observed at a beam energy of 1085 MeV. Neither the GRAZING nor the DNS model correctly describes the measured TLF and PLF yields in this lower- energy reaction but the ImQMD model describes these yields adequately.

OBJECTIVE To compare mechanical bowel preparation (MBP) using oral magnesium citrate with sodium phosphate enema to sodium phosphate (NaP) enema alone during minimally invasive pelvic reconstructive surgery. METHODS We conducted a single-blind, randomized controlled trial of MBP versus NaP in women undergoing minimally invasive pelvic reconstructive surgery. The primary outcome was intraoperative quality of the surgical field. Secondary outcomes included surgeon assessment of bowel handling and patient-reported tolerability symptoms. RESULTS One hundred fifty-three participants were enrolled; 148 completed the study (71 MBP and 77 NaP). Patient demographics, clinical and intraoperative characteristics were similar. Completion of assigned bowel preparation was similar between MBP (97.2%) and NaP (97.4%). The MBP group found the preparation more difficult (P

Exposure to solar ultraviolet (UV) radiation causes photochemical damage near the exposed surface, which results in the degradation of composite reinforcing elements. To minimise the UV degradation, epoxy polymers are being applied as protective coatings to composite materials to retain properties during their design service life. In this study, the effects of UV exposure on the physical, mechanical, and thermo-mechanical properties, including the microstructure particulate-filled epoxy-based polymer coating, were investigated. The polymer coating contains up to 60% by volume of hydrated alumina powder fire retardant (FR) and fillers such as an industrial waste like fly ash (FA) and is exposed to simulated UV conditions either 1000 h or 2000 h. Physical observations showed yellowing at the surface of neat epoxy coating after UV exposure but the presence of particulate FR and FA fillers minimised fading and weight loss. Similarly, no reduction in the flexural strength was observed for polymer coating containing at least 40% fillers, indicating that the FR and FA retained the structural performance of the coating. SEM observation revealed formation of microcracks in the surface of the neat epoxy resin but a dense microstructure in particulate filled epoxy resin after exposure to UV radiation. FTIR analyses indicated that photo-degradation due to UV radiation was limited only on the thin surface of the coating. From the results of this study, a coating thickness of at least 11 mm is required for epoxy based polymer coating with 60% by volume fillers, which is 5 times thinner than neat epoxy resin, to provide 100 years of UV resistance.

Glass Fiber Reinforced Polymers (GFRP) composites have become the materials of interest in replacing steel, wood, and concrete in building and construction. However, limited understanding of degradation mechanisms under physical and chemical aging of GFRP composites is still a concern preventing the widespread implementation and use of this new and emerging material in civil infrastructure. In this work, accelerated aging data for GFRP vinyl-ester composites conditioned at varying pH (2 to 13) and temperature (−22 °C to 71 °C) were collected from laboratory testing and from literature, and compared with the natural aging data under natural environment. It focuses on interlaminar shear strength (ILSS) as this is the most significantly affected property when composites are exposed to aggressive environments. High pH environment and high temperature are found to be most detrimental to GFRP composites where loss in ILSS of up to 30% was measured within the first 80 to 100 days of aging. Arrhenius model and time shift factors were used to correlate the accelerated aging data to the degradation of composites in a neutral pH environment under natural conditions. The correlation between field (natural) and accelerated aging data showed that 30% degradation of ILSS in composites occurs within the first 3 to 10 years of service, followed by a more gradual decrease. Service knock-down factors were then established in order to take into consideration the environmental and chemical effects surrounding the design of GFRP composites over a 100-year service life.

This paper investigated the physical, mechanical, thermo-mechanical and microstructural properties of an epoxy-based resin system containing fire retardant and fly-ash under accelerated hygrothermal ageing. The particulate-filled epoxy resin was conditioned for 1000, 2000 and 3000 h at temperatures up to 60 °C and a relative humidity of 98%. Inclusion of fillers was found to decrease the moisture absorption, increase the glass transition temperature and slight reduce the mechanical properties after hygrothermal conditioning. The prediction using the Arrhenius model suggested that the particulate-filled epoxy resin will retain at least 70% of its strength after 100 years of service in the Australian environment.