Collision Enhanced Raman Scattering (CERS): An Ultra-High Efficient Raman Enhancement Technique for Hollow Core Photonic Crystal Fiber Based Raman Spectroscopy Gas Analyzer.

Raman enhancement techniques are essential for gas analysis to increase the detection sensitivity of a Raman spectroscopy system. We have developed an efficient Raman enhancement technique called the collision-enhanced Raman scattering (CERS), where the active Raman gas as the analyte is mixed with a buffer gas inside the hollow-core photonic-crystal fiber (HCPCF) of a fiber-enhanced Raman spectroscopy (FERS) system. This results in an enhanced Raman signal from the analyte gas. In this study, we first showed that the intensity of the 587 cm-1 stimulated Raman scattering (SRS) peak of H2 confined in an HCPCF is enhanced by as much as five orders of magnitude by mixing with a buffer gas such as helium or N2. Secondly, we showed that the magnitudes of Raman enhancement depend on the type of buffer gas, with helium being more efficient compared to N2. This makes helium a favorable buffer gas for CERS. Thirdly, we applied CERS for Raman measurements of propene, a metabolically interesting volatile organic compound (VOC) with an association to lung cancer. CERS resulted in a substantial enhancement of propene Raman peaks. In conclusion, the CERS we developed is a simple and efficient Raman-enhancing mechanism for improving gas analysis. It has great potential for application in breath analysis for lung cancer detection.

Effective Use of Sugarcane-Bagasse-Derived KOH-Activated Biochar for Remediating Norfloxacin-Contaminated Water.

Bagasse-derived biochar (SCB750) was prepared at 750 °C using Chinese sugarcane bagasse as a carbon source and then modified with KOH for the removal of the antibiotic norfloxacin (NOR) from aqueous solutions. 3K-SCB750, prepared using a solid-to-liquid mass ratio of bagasse:KOH = 1:3, was found to have the best adsorption performance for NOR. Under the conditions of pH 5, 25 °C, 2.4 g L-1 adsorbent, and 300 mg L-1 NOR, its adsorption of NOR reached equilibrium (97.5% removal) after 60 min. The adsorption behaviours were in line with the quasi-second-order kinetic and Langmuir isotherm models, respectively. The maximum theoretical adsorption capacity reached up to 157.4 mg·g-1 at 40 °C. The thermodynamic parameters showed that the adsorption of NOR onto 3K-SCB750 was a spontaneous, endothermic, and physical process. In addition, Brunauer-Emmett-Teller analysis (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy were conducted to investigate the structural and adsorption properties of 3K-SCB750. Fourier transform infrared spectroscopy (FTIR) was also applied to understand the mechanism of adsorption of NOR onto 3K-SCB750. All of the results indicated that 3K-SCB750 had a large specific surface area of 1038.8 m2·g-1, an average pore size of 1.9 nm, and hierarchical structures with random pores and cracks for efficient removal of NOR. NOR adsorption mechanisms on 3K-SCB750 were related to the pore-filling effect and electrostatic attraction. Therefore, 3K-SCB750 biochar may be used as a promising adsorbent of antibiotics in wastewaters.

A New Gas Analysis Method Based on Single-Beam Excitation Stimulated Raman Scattering in Hollow Core Photonic Crystal Fiber Enhanced Raman Spectroscopy.

We previously developed a hollow-core photonic crystal fiber (HCPCF) based Raman scattering enhancement technique for gas/human breath analysis. It enhances photon-gas molecule interactions significantly but is still based on CW laser excitation spontaneous Raman scattering, which is a low-probability phenomenon. In this work, we explored nanosecond/sub-nanosecond pulsed laser excitation in HCPCF based fiber enhanced Raman spectroscopy (FERS) and successfully induced stimulated Raman scattering (SRS) enhancement. Raman measurements of simple and complex gases were performed using the new system to assess its feasibility for gas analysis. We studied the gas Raman scattering characteristics, the relationship between Raman intensities and pump energies, and the energy threshold for the transition from spontaneous Raman scattering to SRS. H2, CO2, and propene (C3H6) were used as test gases. Our results demonstrated that a single-beam pulsed pump combined with FERS provides an effective Raman enhancement technique for gas analysis. Furthermore, an energy threshold for SRS initiation was experimentally observed. The SRS-capable FERS system, utilizing a single-beam pulsed pump, shows great potential for analyzing complex gases such as propene, which is a volatile organic compound (VOC) gas, serving as a biomarker in human breath for lung cancer and other human diseases. This work contributes to the advancement of gas analysis and opens alternative avenues for exploring novel Raman enhancement techniques.

A Modified Embedded-Atom Method Potential for a Quaternary Fe-Cr-Si-Mo Solid Solution Alloy.

Ferritic-martensitic steels, such as T91, are candidate materials for high-temperature applications, including superheaters, heat exchangers, and advanced nuclear reactors. Considering these alloys' wide applications, an atomistic understanding of the underlying mechanisms responsible for their excellent mechano-chemical properties is crucial. Here, we developed a modified embedded-atom method (MEAM) potential for the Fe-Cr-Si-Mo quaternary alloy system-i.e., four major elements of T91-using a multi-objective optimization approach to fit thermomechanical properties reported using density functional theory (DFT) calculations and experimental measurements. Elastic constants calculated using the proposed potential for binary interactions agreed well with ab initio calculations. Furthermore, the computed thermal expansion and self-diffusion coefficients employing this potential are in good agreement with other studies. This potential will offer insightful atomistic knowledge to design alloys for use in harsh environments.

One dimensional wormhole corrosion in metals.

Corrosion is a ubiquitous failure mode of materials. Often, the progression of localized corrosion is accompanied by the evolution of porosity in materials previously reported to be either three-dimensional or two-dimensional. However, using new tools and analysis techniques, we have realized that a more localized form of corrosion, which we call 1D wormhole corrosion, has previously been miscategorized in some situations. Using electron tomography, we show multiple examples of this 1D and percolating morphology. To understand the origin of this mechanism in a Ni-Cr alloy corroded by molten salt, we combined energy-filtered four-dimensional scanning transmission electron microscopy and ab initio density functional theory calculations to develop a vacancy mapping method with nanometer-resolution, identifying a remarkably high vacancy concentration in the diffusion-induced grain boundary migration zone, up to 100 times the equilibrium value at the melting point. Deciphering the origins of 1D corrosion is an important step towards designing structural materials with enhanced corrosion resistance.

Virtual interprofessional education to support medical laboratory technologists' participation in interprofessional collaborative practice within integrated healthcare models.

Interprofessional collaborative practice is a key requirement for the successful implementation of integrated healthcare models. Current interprofessional education opportunities seldom include medical laboratory technologists who oversee the production of data that informs the diagnosis, treatment, and monitoring of patients. Errors in the laboratory process mostly occur in the pre-analytical and post-analytical phases, which both involve the need for collaboration between medical laboratory technologists and other healthcare providers. In this article, we introduce and describe an innovative work-integrated virtual learning experience that provides technologists with the opportunity to fully participate in interprofessional education.

Identifying changes in e-cigarette use among a longitudinal sample of Canadian youth e-cigarette users in the COMPASS cohort study, 2017/18-2018/19.

Objectives: There are few studies describing longitudinal changes in vaping patterns among current youth e-cigarette users. The objective of this study was to identify-one-year changes in e-cigarette use patterns among a longitudinal sample of Canadian youth e-cigarette users between 2017/18 and 2018/19. Methods: The longitudinal sample included n = 4,071 current (past 30-day) e-cigarette users in grades 9-11 attending schools in four Canadian provinces. Students reported the number of days they used e-cigarettes in the past 30 days in 2017/18 and 2018/19. Based on responses, students could have escalated, reduced, stopped, or maintained their level of vaping. The prevalence of each e-cigarette use pattern was identified across demographic characteristics and regression models identified significant predictors of each use pattern. Results: Over one year, 49.2% of current youth e-cigarette users escalated, 12.8% reduced, 20.2% stopped, and 17.8% maintained their frequency of e-cigarette use. Baseline e-cigarette use frequencies varied according to use pattern. Current youth e-cigarette users with higher baseline vaping frequencies had lower odds of escalating and stopping e-cigarette use and higher odds of reducing e-cigarette use relative to maintaining the same frequency of use. Conclusions: While about half of current youth e-cigarette users increased their frequency of e-cigarette use over a 1-year period, a significant number also decreased or stopped vaping at a time when the prevalence of youth e-cigarette use increased rapidly in Canada. There is a need for longitudinal data to monitor and evaluate changes to e-cigarette use patterns that may be in response to changing public health policies.

Revealing hidden defects through stored energy measurements of radiation damage.

With full knowledge of a material's atomistic structure, it is possible to predict any macroscopic property of interest. In practice, this is hindered by limitations of the chosen characterization techniques. For example, electron microscopy is unable to detect the smallest and most numerous defects in irradiated materials. Instead of spatial characterization, we propose to detect and quantify defects through their excess energy. Differential scanning calorimetry of irradiated Ti measures defect densities five times greater than those determined using transmission electron microscopy. Our experiments also reveal two energetically distinct processes where the established annealing model predicts one. Molecular dynamics simulations discover the defects responsible and inform a new mechanism for the recovery of irradiation-induced defects. The combination of annealing experiments and simulations can reveal defects hidden to other characterization techniques and has the potential to uncover new mechanisms behind the evolution of defects in materials.

Maintaining a social license to operate for wastewater-based monitoring: The case of managing infectious disease and the COVID-19 pandemic.

Wastewater monitoring as a public health tool is well-established and the SARS-CoV-2 (COVID-19) pandemic has seen its widespread uptake. Given the significant potential of wastewater monitoring as a public health surveillance and decision support tool, it is important to understand what measures are required to allow the long-term benefits of wastewater monitoring to be fully realized, including how to establish and/or maintain public support. The potential for positive SARS-CoV-2 detections to trigger enforced, community-wide public health interventions (e.g., lockdowns and other impacts on civil liberties) further emphasises the need to better understand the role of public engagement in successful wastewater-based monitoring programs. This paper systematically reviews the processes of building and maintaining the social license to operate wastewater monitoring. We specifically explore the relationship between different stakeholder communities and highlight the information and actions that are required to establish a social license to operate and then prevent its loss. The paper adds to the literature on social license to operate by extending its application to new domains and offers a dynamic model of social license to help guide the agenda for researcher and practitioner communities.

The [13 C]octanoic acid breath test for gastric emptying quantification: A focus on nutrition and modeling.

Gastric emptying (GE) is the process of food being processed by the stomach and delivered to the small intestine where nutrients such as lipids are absorbed into the blood circulation. The combination of an easy and inexpensive method to measure GE such as the CO2 breath test using the stable isotope [13 C]octanoic acid with semi-mechanistic modeling could foster a wider application in nutritional studies to further understand the metabolic response to food. Here, we discuss the use of the [13 C]octanoic acid breath test to label the solid phase of a meal, and the factors that influence GE to support mechanistic studies. Furthermore, we give an overview of existing mathematical models for the interpretation of the breath test data and how much nutritional studies could benefit from a physiological based pharmacokinetic model approach.

Factors Associated with E-Cigarette Escalation among High School Students: A Review of the Literature.

BACKGROUND: E-cigarette use has been identified as a behaviour of concern among adolescents, and ever and daily use among this population has increased recently. The purpose of this review was to summarize the relevant studies investigating the frequency and intensity of e-cigarette use in adolescents and the factors associated with these patterns of use. METHODS: A scoping search of two databases was conducted to identify longitudinal studies examining escalating e-cigarette use among adolescents. Escalating e-cigarette use could refer to an increasing frequency or intensity of use over time. Articles were screened for relevance. Studies that met inclusion criteria were included for synthesis. RESULTS: Five articles were included for synthesis. All five articles were longitudinal studies taking place in the United States between 2013 and 2017. Age, gender, cost of e-cigarettes, use of cigarettes, polysubstance use, and e-liquid nicotine concentration were associated with escalation of e-cigarette use. CONCLUSIONS: A paucity of information exists regarding the escalation of e-cigarette use among adolescents. Given the changing popularity of devices, additional updated evidence is needed to understand the factors associated with the escalation of e-cigarette use among adolescents, which can be used to inform local and national programs and policies.

Design and performance of a molten fluoride salt-compatible optical thermophysical property measurement system.

Accurate knowledge of molten salt thermophysical properties is crucial to optimize the efficiency, safety, and reliability of molten salt based energy applications. For molten fluorides, currently of high interest for fission and fusion reactors, data regarding these properties are either poor or non-existent. Thermal diffusivity and sound speed in particular play important roles in the modeling of a reactor's steady state, transient, and accident scenarios. Fluoride salt-compatible property measurement systems have thus far been the bottleneck in accurately obtaining these properties. We present the design of an optical system optimized for molten fluoride salt thermophysical property measurement, along with characterization of its thermal performance. Demonstration of system capabilities is achieved through acquisition of sound speed and thermal diffusivity in lithium chloride (LiCl), showing excellent agreement with literature data.

Inactivation, removal, and regrowth potential of opportunistic pathogens and antimicrobial resistance genes in recycled water systems.

With two thirds of the global population living in areas affected by water scarcity, wastewater reuse is actively being implemented or explored by many nations. There is a need to better understand the efficacy of recycled water treatment plants (RWTPs) for removal of human opportunistic pathogens and antimicrobial resistant microorganisms. Here, we used a suite of probe-based multiplex and SYBR green real-time PCR assays to monitor enteric opportunistic pathogens (EOPs; Acinetobacter baumannii, Arcobacter butzlieri, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Legionella spp., Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Enteritidis, Streptococcus spp.) and antimicrobial resistance genes (ARGs; qnrS, blaSHV, blaTEM, blaGES, blaKPC, blaIMI, blaSME, blaNDM, blaVIM, blaIMP, blaOXA-48-like, mcr-1 and mcr-3) of key concern from an antimicrobial resistance (AMR), waterborne and foodborne disease perspective. The class 1 integron-integrase gene (intl1) was quantified as a proxy for multi-drug resistance. EOPs, intl1 and ARGs absolute abundance (DNA and RNA) and metabolic activity (RNA) was assessed through three RWTPs with differing treatment trains. Our results indicate that RWTPs produced high quality recycled water for non-potable reuse by removing >95% of EOPs and ARGs, however, subpopulations of EOPs and ARGs survived disinfection and demonstrated potential to become actively growing members of the recycled water and distribution system microbiomes. The persistence of functional intl1 suggests that significant genetic recombination capacity remains in the recycled water, along with the likely presence of multi-drug resistant bacteria. Results provide new insights into the persistence and growth of EOPs, and prevalence and removal of ARGs in recycled water systems. These data will contribute towards the emerging evidence base of AMR risks in recycled water to inform quantitative risk-based policy development regarding water recycling schemes.

Passivation of pyrite for reduced rates of acid and metalliferous drainage using readily available mineralogic and organic carbon resources: A laboratory mine waste study.

Acid and metalliferous drainage (AMD) is a major environmental issue resulting largely from exposure to weathering of mine wastes containing pyrite (FeS2). At-source strategies to reduce the rate of formation of AMD have potential to be more cost-effective and sustainable than post-generation downstream treatments. The objective of this study was to examine the efficacy of geochemical and microbial treatments for at-source control through pyrite surface passivation. Six kinetic leach columns (KLCs), using a mine waste containing 3.8 wt% pyrite, were subjected to various treatments: 1) untreated, 2) blended calcite, and applications of 3) calcite-saturated water, 4) lime-saturated water followed by calcite-saturated water, 5) biosolids extract water (providing a source of organic carbon to promote microbial growth) and 6) biosolids extract in calcite-saturated water. The untreated KLC leachate pH was on average 5.7 for the first 12 weeks, followed by a gradual decrease to pH 4.5 at week 52. This slow pH decrease is attributed to neutralisation released upon Mg-siderite dissolution. The leachate pH from all treated KLCs was near-neutral at the end of the tests. Pyrite was surface-passivated and leaching supressed by all treatments except for calcite-saturated water. Leaching of Mn and Zn from the untreated waste identified the potential for adverse environmental impact. No evidence was found for surface passivation of Zn- or Mn-containing minerals in the treated KLCs. Blended calcite addition and lime-saturated water followed by calcite-saturated water were most effective at reducing release of Zn and Mn, likely due to precipitation as hydroxides/carbonates.

3D Printed frames to enable reuse and improve the fit of N95 and KN95 respirators.

BACKGROUND: In response to supply shortages caused by the COVID-19 pandemic, N95 filtering facepiece respirators (FFRs or "masks"), which are typically single-use devices in healthcare settings, are routinely being used for prolonged periods and in some cases decontaminated under "reuse" and "extended use" policies. However, the reusability of N95 masks is limited by degradation of fit. Possible substitutes, such as KN95 masks meeting Chinese standards, frequently fail fit testing even when new. The purpose of this study was to develop an inexpensive frame for damaged and poorly fitting masks using readily available materials and 3D printing. RESULTS: An iterative design process yielded a mask frame consisting of two 3D printed side pieces, malleable wire links that users press against their face, and cut lengths of elastic material that go around the head to hold the frame and mask in place. Volunteers (n = 45; average BMI = 25.4), underwent qualitative fit testing with and without mask frames wearing one or more of four different brands of FFRs conforming to US N95 or Chinese KN95 standards. Masks passed qualitative fit testing in the absence of a frame at rates varying from 48 to 94 % (depending on mask model). For individuals who underwent testing using respirators with broken or defective straps, 80-100 % (average 85 %) passed fit testing with mask frames. Among individuals who failed fit testing with a KN95, ~ 50 % passed testing by using a frame. CONCLUSIONS: Our study suggests that mask frames can prolong the lifespan of N95 and KN95 masks by serving as a substitute for broken or defective bands without adversely affecting fit. Use of frames made it possible for ~ 73 % of the test population to achieve a good fit based on qualitative and quantitative testing criteria, approaching the 85-90 % success rate observed for intact N95 masks. Frames therefore represent a simple and inexpensive way of expanding access to PPE and extending their useful life. For clinicians and institutions interested in mask frames, designs and specifications are provided without restriction for use or modification. To ensure adequate performance in clinical settings, fit testing with user-specific masks and PanFab frames is required.

The ventilation of buildings and other mitigating measures for COVID-19: a focus on wintertime.

The year 2020 has seen the emergence of a global pandemic as a result of the disease COVID-19. This report reviews knowledge of the transmission of COVID-19 indoors, examines the evidence for mitigating measures, and considers the implications for wintertime with a focus on ventilation.

Analysis of nitrous oxide emissions from aerobic granular sludge treating high saline municipal wastewater.

Conventional activated sludge (CAS)-based wastewater treatment processes have the potential to emit high concentrations of nitrous oxide (N2O) during nitrification and denitrification, which can significantly impact the environmental performance and carbon footprint of wastewater treatment operations. While N2O emissions from CAS have been extensively studied, there is little knowledge of N2O emissions from aerobic granular sludge (AGS) which is now an increasingly popular secondary treatment alternative. The N2O emissions performance of AGS needs to be investigated to ensure that the positive benefits of AGS, such as increased capacity and stable nutrient removal, are not offset by higher emissions. This study quantified N2O emissions from a pilot-scale AGS reactor operated under a range of organic loading rates. A second CAS pilot plant was operated in parallel and under identical loading rates to allow for side-by-side comparison of N2O emissions from floc-based activated sludge. Under low loadings of <0.6 kg COD/m3/d the N2O emission factor from AGS and CAS were similar, at around 1.46 ± 0.1% g N2Oemitted/g ammonium loaded. A step increase in the organic loading rate increased N2O emissions from AGS more so than CAS which appeared to be attributed to the reactor feeding strategy that was required for AGS formation. The use of a separate anaerobic feeding phase which was followed by the aeration phase, resulted in extended periods of low dissolved oxygen (DO) concentrations combined with an initial high biomass ammonium loading rate, which favours N2O production and was exacerbated at higher organic loads. Conversely, the combined feeding plus aeration operation (aerobic feed) employed by the CAS system enabled a more even biomass ammonium loading rate and DO supply. This work has shown that while AGS has many operational benefits, the impacts that aeration profile, loading rate and feeding strategy have on N2O emissions must be considered.

3D Printed frames to enable reuse and improve the fit of N95 and KN95 respirators.

BACKGROUND: In response to supply shortages during the COVID-19 pandemic, N95 filtering facepiece respirators (FFRs or "masks"), which are typically single-use devices in healthcare settings, are routinely being used for prolonged periods and in some cases decontaminated under "reuse" and "extended use" policies. However, the reusability of N95 masks is often limited by degradation or breakage of elastic head bands and issues with mask fit after repeated use. The purpose of this study was to develop a frame for N95 masks, using readily available materials and 3D printing, which could replace defective or broken bands and improve fit. RESULTS: An iterative design process yielded a mask frame consisting of two 3D-printed side pieces, malleable wire links that users press against their face, and cut lengths of elastic material that go around the head to hold the frame and mask in place. Volunteers (n= 41; average BMI= 25.5), of whom 31 were women, underwent qualitative fit with and without mask frames and one or more of four different brands of FFRs conforming to US N95 or Chinese KN95 standards. Masks passed qualitative fit testing in the absence of a frame at rates varying from 48 - 92% (depending on mask model and tester). For individuals for whom a mask passed testing, 75-100% (average = 86%) also passed testing with a frame holding the mask in place. Among users for whom a mask failed in initial fit testing, 41% passed using a frame. Success varied with mask model and across individuals. CONCLUSIONS: The use of mask frames can prolong the lifespan of N95 and KN95 masks by serving as a substitute for broken or defective bands without adversely affecting fit. Frames also have the potential to improve fit for some individuals who cannot fit existing masks. Frames therefore represent a simple and inexpensive way of extending the life and utility of PPE in short supply. For clinicians and institutions interested in mask frames, designs and specifications are provided without restriction for use or modification. To ensure adequate performance in clinical settings, qualitative fit testing with user-specific masks and frames is required.