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Chemometric techniques such as partial least-squares (PLS) regression have been applied with huge success to a wide array of chemical problems including multicomponent analysis of analytes in complex mixtures. Despite this, there are few examples of laboratory pedagogical exercises that involve students in the acquisition of chemical data from infrared spectroscopic-based instrumentation, followed by quantitative chemometric analysis using PLS. In this article, we present a computational activity that introduces undergraduate students in an instrumental analysis laboratory setting to data acquisition using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy followed by data analysis using PLS. The first part of the activity involved students creating mixture designs of binary terpene components consisting of p-cymene and limonene. These mixtures were then analyzed using an ATR-FTIR spectrometer, where students became familiarized with the instrument and were shown how to characterize and differentiate the aforementioned terpenes using their generated FTIR spectra. The second part of the activity involved preprocessing the acquired FTIR spectral data from the first part followed by the simultaneous quantitative determination of the prepared terpenes using PLS. On the basis of student surveys, it can be concluded that this convenient and inexpensive activity was ultimately successful in introducing students to the use of chemometrics for quantitative analysis of terpenes using an ATR-FTIR. This easy-to-do two-week activity can be used as a standalone for instrumental analysis laboratory classes and can even be integrated in advanced courses in applied spectroscopy and chemometrics.

The SIR model is a differential equations based model of the spread of an infectious disease that compartmentalises individuals in a population into one of three states: those who are susceptible to a disease (S), those who are infected and can transmit the disease to others (I), and those who have recovered from the disease and are now immune (R). This "Classroom Note" describes how to initiate teaching the SIR model with two concrete physical simulations to provide students with first-hand experience with some of the nuanced behaviour of how an infectious disease spreads through a closed population. One simulation physically models disease spread by the exchange of fluids, using pH to simulate infection. A second simulation incorporates randomness through the use of a probability game to keep track of the state of each individual at each time step. Both simulations invite students to ask questions about what factors influence disease spread. The concrete experience from the physical simulations enables students to make connections to the abstract mathematical representation of the SIR model and discuss the sources of stochasticity present in the spread of an infectious disease.

At its simplest, paint pouring is the mixing of paints with lower density and viscosity liquids and then pouring them onto a surface for an aesthetic artifact. Using active art as a teaching tool, middle school students were engaged in a paint pouring activity to study the influence of the interdisciplinary combination of chemistry and art topics on student understanding of density, viscosity, and creativity. It is accepted that hands-on activities increase the understanding of complex topics because students are able to apply these topics to real-world applications. Survey analysis (N = 124) of a pre- and post-event survey with 14 Likert scale questions broken into the following categories: density, science and creativity, viscosity, and art. The pre- and post-surveys included three multiple-choice questions indicating that student's understanding of the importance of density and viscosity in art increased after completing the activity. Of the 14 Likert scale questions, 11 showed an increased self-reported understanding of the scientific concepts and enthusiasm for art after engaging in the paint pouring exercise. Three responses did not increase, as the students already wanted to complete a paint pour and recognized paint pouring as an art activity. It was also observed that, after completing the exercise, students were receptive to how science and art can be integrated. Correct student responses to the multiple choice all increased in the post-survey, providing evidence for the self-reported increased student understanding of density and viscosity.

Herein, two simulated electrochemistry experiments, namely, the (i) electrochemical series, using an electronic half-cell module, and (ii) citrus fruit battery series are demonstrated for undergraduate chemistry students. The demonstration can be performed for in-person and remote students by connecting the electronic half-cell module to a computer. Remote students can participate in the demonstration on the Internet and interact with the instructor and other students. This experiment does not require the use of metal and metal ion solutions for the construction of citrus fruit batteries and electrochemical series. Therefore, this demonstration is environmentally green, because no chemical waste is produced at the end of the demonstration.

In this laboratory experiment, students explore the aquatic photochemical fate of ranitidine and cimetidine, two common pharmaceutical pollutants found in wastewater. It provides an engaging environmental context for students to develop knowledge of reaction kinetics and photochemistry as well as skill in using analytical instrumentation. This versatile experiment consists of two basic modules, three optional advanced modules, and additional add-ons that may be performed in various combinations to meet the unique learning objectives of general, analytical, physical, and environmental chemistry courses and science outreach activities. It may be performed as a traditional lab experiment or as an entirely remote exercise with an increased focus on data analysis and interpretation using provided example data sets. All of the photolysis experiments are carried out by preparing solutions of ranitidine or cimetidine in various matrices, irradiating the samples, and periodically removing subsamples for HPLC analysis of the compound of interest. Pseudo-first order kinetic plots are then generated to determine rate constants that are used to draw conclusions about photolysis pathways or to calculate additional kinetic parameters. In the two basic modules, cimetidine is found to degrade appreciably only when irradiated in the presence natural organic matter (NOM), indicating an indirect, photosensitized degradation pathway. In contrast, ranitidine degrades in pure buffer and in the presence of NOM with comparable rate constants, highlighting the predominant role of direct photolysis. In the advanced modules, students calculate ranitidine direct photolysis quantum yields and examine the significance of singlet oxygen as a photochemically produced reactive intermediate. The two basic modules may be completed in two 3 hour lab periods, while the advanced modules require additional time. This experiment requires only an HPLC instrument, inexpensive chemicals, and common glassware and lab equipment if performed in person and a personal computer if performed remotely.

This work describes a semester-long learning module designed to equip students with the analytical and practical skills necessary to be successful in an interdisciplinary polymer research environment. This learning module combines laboratory experiments involving both synthesis and materials characterization with lectures in polymer theory, and encourages chemists and engineers to learn alongside one another. Specifically, students learn air-free Schlenk technique to facilitate the atom transfer radical polymerization (ATRP) of a series of homo- and copolymers made from n-butyl methacrylate (BMA) and methyl methacrylate (MMA) monomers. Students analyze these polymers using techniques that traverse the interdisciplinary spectrum--including Gel Permeation Chromatography (GPC), Proton-Nuclear Magnetic Resonance (1H NMR) spectroscopy, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Dynamic Mechanical Analysis (DMA)--and learn about the theory and mathematics behind the measurements. Ultimately, this hands-on experience in polymer material design bridges the structure--property relationships taught by classical and applied polymer theory.

Despite its vital importance in our lives, chemistry is inadequately represented in most museums. Issues such as safety, replenishing and disposal of chemicals, supervision required, and cost are constraints that have limited the number and size of chemistry exhibits. Taking into account the constraints, a 21-station interactive and inexpensive chemistry exhibit has been designed, constructed, and installed in the Great Valley Museum on the Modesto Junior College West Campus. The exhibit is intended to stimulate interest in chemistry, demonstrate and emphasize the importance of chemistry in our lives, and provide a meaningful and enjoyable educational experience with chemistry. The centerpiece of the exhibit involves the identification of 11 elements from observations of relative density, electrical conductivity, magnetic properties, color, and luster. Descriptions of the 21 stations are included in this paper.

Changes in the availability of a subset of aerosol known as ice-nucleating particles (INPs) can substantially alter cloud microphysical and radiative properties. Despite very large spatial and temporal variability in INP properties, many climate models do not currently represent the link between (i) the global distribution of aerosols and INPs and (ii) primary ice production in clouds. Here we use the UK Earth System Model to simulate the global distribution of dust, marine-sourced, and black carbon INPs suitable for immersion-mode freezing of liquid cloud droplets over an annual cycle. The model captures the overall spatial and temporal distribution of measured INP concentrations, which is strongly influenced by the world's major mineral dust source regions. A negative bias in simulated versus measured INP concentrations at higher freezing temperatures points to incorrectly defined INP properties or a missing source of INPs. We find that the ability of the model to reproduce measured INP concentrations is greatly improved by representing dust as a mixture of mineralogical and organic ice-nucleating components, as present in many soils. To improve the agreement further, we define an optimized hypothetical parameterization of dust INP activity (ns(T)) as a function of temperature with a logarithmic slope of −0.175 K−1, which is much shallower than existing parameterizations (e.g. −0.35 K−1 for the K-feldspar data of Harrison et al., 2019). The results point to a globally important role for an organic component associated with mineral dust.

We present mass spectroscopic in situ data from rocket flights of two improved ion mass spectrometers in the mesosphere and lower thermosphere region. The instruments were optimized to detect large ions with a mass-to-charge ratio (m/z, mass) of up to m/z 2000 and 20 000 respectively, for analysis of meteor smoke particles. The flights were performed in the framework of the polar mesospheric winter echo (PMWE) campaigns, initiated and coordinated by the Leibniz Institute of Atmospheric Physics (IAP), to investigate polar mesospheric winter radar echoes in Andøya (Norway) in 2018 and 2021. Both flights were successful and allowed the mass number and chemical composition of charged meteor smoke particles to be investigated. We found a complex and diverse composition of positively and negatively charged molecules and particles within our mass range in a region that is notoriously difficult to get mass spectroscopic data from. While at altitudes below 85 km we observed negatively charged particles of up to several thousands of atomic mass units, above this altitude we found possible building blocks of these large particles that form right after their ablation from the parent meteorite material. In the first flight we detected no positively charged particles above m/z 100 and a difficult-to-interpret signal for negatively charged particles beyond our mass range of m/z 2000. In the second flight, however, we detected positively charged particles between around m/z 180 and 350 and a number of different negatively charged particles up to m/z 5500. Due to the very large mass range of m/z 20 000 used in the second flight and the subsequent lower mass resolution, unambiguous mass identification is not possible. A particular interesting pattern was found at 80.8 km of a compound that seems to double its mass around m/z 225, 450, 900 and 1800. Comparing our findings to proposed meteor smoke particle compounds by other authors, our observations would be consistent with magnetite, fayalite and forsterite. However, other possible compounds cannot be excluded.

Graphene's unique combination of exceptional mechanical, electronic, and thermal properties makes this material a promising candidate to enable next-generation technologies in a wide range of fields, including electronics, energy, and medicine. However, educational activities involving graphene have been limited due to the high expense and complexity associated with fabricating and characterizing graphene. Here, we demonstrate an economical, safe, and simple technique to synthesize multilayer graphene films via chemical vapor deposition in 30-45 min in a classroom setting. Raman spectroscopy indicates that the graphene is of high quality, scanning electron microscopy shows that the films are continuous over large areas, and oxidation studies demonstrate graphene's high impermeability. The films are also transferred to insulating, optically transparent substrates, which enables measurement of the high electrical conductivity of graphene and direct visualization of several layers of atoms. This graphene synthesis has been successfully implemented in diverse settings with students ranging in education level from 5th grade to undergraduate. In addition to reinforcing fundamental concepts at the core of chemical education, this experiment introduces students to cutting-edge nanotechnology research.

New particle formation (NPF) involving organic compounds has been identified as an important process affecting aerosol particle number concentrations in the global atmosphere. Laboratory studies have shown that highly oxygenated organic molecules (HOMs) can make a substantial contribution to NPF, but there is a lack of global model studies of NPF with detailed HOM chemistry. Here, we incorporate a state-of-the-art biogenic HOM chemistry scheme with 96 chemical reactions to a global chemistry–climate model and quantify the contribution to global aerosols through HOM-driven NPF. The updated model captures the frequency of NPF events observed at continental surface sites (normalized mean bias changes from −96 % to −15 %) and shows reasonable agreement with measured rates of NPF and sub-20 nm particle growth. Sensitivity simulations show that compared to turning off the organic nucleation rate, turning off organic initial growth results in a more substantial decrease in aerosol number concentrations. Globally, organics contribute around 45 % of the annual mean vertically integrated nucleation rate (at 1.7 nm) and 25 % of the vertically averaged growth rate. The inclusion of HOM-related processes leads to a 39 % increase in the global annual mean aerosol number burden and a 33 % increase in cloud condensation nuclei (CCN) burden at 0.5 % supersaturation compared to a simulation with only inorganic nucleation. Our work predicts a greater contribution of organic nucleation to NPF than previous studies due to the semi-explicit HOM mechanism and an updated inorganic NPF scheme. The large contribution of biogenic HOMs to NPF on a global scale could make aerosol sensitive to changes in biogenic emissions.

Abstract A Pro‐Gly‐typed cyclopeptide, cyclosenegalin A, was firstly isolated from Annona senegalensis and Annona scleroderma. In this study, we reported synthesis the cycloheptapeptide with a combination of solid‐ and solution‐phase synthetic methods. This study also compared the effectiveness of β‐turn inducer type I and II in cyclosenegalin A to facilitate the cyclization process. The synthesis of cyclosenegalin A were prepared using two different sequences of linear peptides for cyclization. First sequence employed β‐turn type I inducer (Ser‐Ala‐Val‐Thr) as turning point and second sequence employed β‐turn type II inducer (Thr‐Pro‐Gly‐Leu). The successful cyclization was obtained using the linear sequence of NH2‐Ala‐Val‐Thr‐Pro‐Gly‐Leu‐Ser‐OH with β‐turn type II. The final product was obtained in 8.2 % yield with PyBOP/DIEA act as coupling agent. The synthetic cyclosenegalin A were characterized with HR‐ToFMS, 1H NMR, 13C NMR, HSQC, HMBC, TOCSY, and ROESY. The synthetic product was also evaluated for its antimicrobial activity.

A multivitamin tablet and liquid are analyzed for the elements calcium, magnesium, iron, zinc, copper, and manganese using atomic absorption spectrometry. Linear calibration and standard addition are used for all elements except calcium, allowing for an estimate of the matrix effects encountered for this complex sample. Sample preparation using standard lab chemicals and equipment allows for this experiment to be easily incorporated into undergraduate analytical laboratory courses. (Contains 1 table and 2 figures.)

Abstract Surface templating by electrostatic surface potentials is the least invasive way to design large-scale artificial nanostructures. However, generating sufficiently large potential gradients remains challenging. Here, we lay the groundwork for significantly enhancing local electrostatic fields by chemical modification of the surface. We consider the hexagonal boron nitride (h-BN) nanomesh on Rh(111), which already exhibits small surface potential gradients between its pore and wire regions. Using photoemission spectroscopy, we show that adding Au atoms to the Rh(111) surface layer leads to a local migration of Au atoms below the wire regions of the nanomesh. This significantly increases the local work function difference between the pore and wire regions that can be quantified experimentally by the changes in the h-BN valence band structure. Using density functional theory, we identify an electron transfer from Rh to Au as the microscopic origin for the local enhancement of potential gradients within the h-BN nanomesh.

Background: This research employs response surface methodology, specifically Central Composite Design (CCD), to optimize the process parameters for the effective production of biodiesel. Jatropha oil was utilized as the raw material to minimize expenses. A nanocatalyst was utilized as a solid catalyst, developed from CaCO3 via waste snail shells, offering advantages such as recyclability and improved catalytic activity during a transesterification process. The developed nanocatalyst was analyzed using various techniques, including dynamic light scattering (DLS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, and Fourier-transform infrared (FTIR). The BET analysis revealed a surface area of 5.1m2/g and the Barrett-Joyner-Halenda (BJH) analysis provided insights into the pore volume and diameter of the synthesized nano-CaO, showing values of 0.002556 cc/g and 1.1 nm, respectively, indicating the presence of both microspores and active sites on the external surface of the nano-CaO catalyst. Biodiesel conversion was controlled by adjusting factors like the methanol to oil ratio, catalyst weight, reaction time, reaction temperature, and agitation speed. A quadratic model was established to explore the correlation between the independent variables and the biodiesel conversion rate. The results showed a maximum biodiesel conversion rate of 96.73% under the optimal conditions: methanol to oil ratio (6:1), catalyst weight (1.4 wt%), reaction time (60 min), reaction temperature (55 °C), and agitation speed (250 rpm). These parameters were determined through 32 experimental trials. The RSM technique yielded impressive results with a determined coefficient of determination (R2) of 0.9834, adjusted R2 of 0.8503, predicted R2 of 0.8309, and a coefficient of variance (CV) 0.75%. Based on the analysis of variance (ANOVA) findings, the model exhibits a high level of significance (p

We investigate the use of atmospheric oxygen (O2) and carbon dioxide (CO2) measurements for the estimation of the fossil fuel component of atmospheric CO2 in the UK. Atmospheric potential oxygen (APO) – a tracer that combines O2 and CO2, minimizing the influence of terrestrial biosphere fluxes – is simulated at three sites in the UK, two of which make APO measurements. We present a set of model experiments that estimate the sensitivity of APO simulations to key inputs: fluxes from the ocean, fossil fuel flux magnitude and distribution, the APO baseline, and the exchange ratio of O2 to CO2 fluxes from fossil fuel combustion and the terrestrial biosphere. To estimate the influence of uncertainties in ocean fluxes, we compare three ocean O2 flux estimates from the NEMO–ERSEM, the ECCO–Darwin ocean model, and the Jena CarboScope (JC) APO inversion. The sensitivity of APO to fossil fuel emission magnitudes and to terrestrial biosphere and fossil fuel exchange ratios is investigated through Monte Carlo sampling within literature uncertainty ranges and by comparing different inventory estimates. We focus our model–data analysis on the year 2015 as ocean fluxes are not available for later years. As APO measurements are only available for one UK site at this time, our analysis focuses on the Weybourne station. Model–data comparisons for two additional UK sites (Heathfield and Ridge Hill) in 2021, using ocean flux climatologies, are presented in the Supplement. Of the factors that could potentially compromise simulated APO-derived fossil fuel CO2 (ffCO2) estimates, we find that the ocean O2 flux estimate has the largest overall influence at the three sites in the UK. At times, this influence is comparable in magnitude to the contribution of simulated fossil fuel CO2 to simulated APO. We find that simulations using different ocean fluxes differ from each other substantially. No single model estimate, or a model estimate that assumed zero ocean flux, provided a significantly closer fit than any other. Furthermore, the uncertainty in the ocean contribution to APO could lead to uncertainty in defining an appropriate regional background from the data. Our findings suggest that the contribution of non-terrestrial sources needs to be better accounted for in model simulations of APO in the UK to reduce the potential influence on inferred fossil fuel CO2 using APO.

For a year, the U.S. Department of Labor's Secretary's Commission on Achieving Necessary Skills (SCANS) commissioners and research team talked with employers, managers, and frontline business workers about skills needed on the job. Certificates reflecting mastery of SCAN competencies, if valued by employers, will change students' perceptions of education-coursework relationships. (MLH)

Distance measurement plays a key role in many fields of science and technology, including robotics, civil engineering, and navigation systems. This paper focuses on analyzing the precision of a measurement system using stereo camera distance measurement technology in the context of measuring two objects of different sizes. The first part of the paper presents key information about stereoscopy, followed by a discussion of the process of building a measuring station. The Mask R-CNN algorithm, which is a deep learning model that combines object detection and instance segmentation, was used to identify objects in the images. In the following section, the calibration process of the system and the distance calculation method are presented. The purpose of the study was to determine the precision of the measurement system and to identify the distance ranges where the measurements are most precise. Measurements were made in the range of 20 to 70 cm. The system demonstrated a relative error of 0.95% for larger objects and 1.46% for smaller objects at optimal distances. A detailed analysis showed that for larger objects, the system exhibited higher precision over a wider range of distances, while for smaller objects, the highest accuracy was achieved over a more limited range. These results provide valuable information on the capabilities and limitations of the measurement system used, while pointing out directions for its further optimization.

Metal-organic frameworks (MOFs) are crystalline materials that are composed of an infinite array of metal nodes (single ions or clusters) linked to one another by polyfunctional organic compounds. Because of their extraordinary surface areas and high degree of control over the physical and chemical properties, these materials have received much attention in the recent literature for industrial applications, such as gas storage. As the applications of MOFs are significant, the underlying concepts for their design and synthesis may be used in the upper-level undergraduate laboratory as a vehicle for promoting student understanding of a wide variety of chemical concepts. These include targeted synthesis, crystallography, and adsorption theory of gases. This laboratory experiment involves the synthesis and full characterization of three MOFs that are derived from inexpensive materials, followed by surface area calculations, and in the case of one material, postsynthetic modification. Owing to the high focus on solid-state characterization, we believe this course will also provide students with a foundation in characterization methods they would not normally encounter in a typical inorganic chemistry laboratory course. (Contains 2 figures and 1 scheme.)

Luminescent carbon dots (CDs) are emerging carbon nanomaterials whose tunable and exceptional optoelectronic properties have found applications as alternatives to traditional fluorophores and metal-based catalysts. Further, they can be easily prepared from biomass and using green solvents. Biomass sources of CDs, however, often result in the formation of thousands of products, which are difficult to separate. In this study CDs were synthesized using a urea-choline chloride deep eutectic solvent and shrimp shell-derived chitin as raw materials through a low-temperature solvothermal treatment. This was followed by a facile liquid-liquid extraction with acetone to improve the optical properties and narrow the size distribution of the CDs. The acetone-extracted CDs (ACDs) showed good performance in photocatalytic degradation of the aquatic pollutant, malachite green. They also show good potential in monitoring various toxic water pollutants through the quenching effect of selected pesticides, antibiotics, heavy metals, and anions on the fluorescence of ACDs. Key words: luminescent nitrogen-doped carbon dots, deep eutectic solvent, solvothermal synthesis, bio-based carbon dots, acetone extraction, malachite green decolourization, Introduction Carbon dots (CDs) refer to a class of carbon-based nanomaterials that exhibit exceptional electrical, optical, and mechanical properties in addition to good biocompatibility low cytotoxicity, and solvent dispersibility. (1) [...]

This study evaluates tropospheric columns of methane, carbon monoxide, and ozone in the Arctic simulated by 11 models. The Arctic is warming at nearly 4 times the global average rate, and with changing emissions in and near the region, it is important to understand Arctic atmospheric composition and how it is changing. Both measurements and modelling of air pollution in the Arctic are difficult, making model validation with local measurements valuable. Evaluations are performed using data from five high-latitude ground-based Fourier transform infrared (FTIR) spectrometers in the Network for the Detection of Atmospheric Composition Change (NDACC). The models were selected as part of the 2021 Arctic Monitoring and Assessment Programme (AMAP) report on short-lived climate forcers. This work augments the model–measurement comparisons presented in that report by including a new data source: column-integrated FTIR measurements, whose spatial and temporal footprint is more representative of the free troposphere than in situ and satellite measurements. Mixing ratios of trace gases are modelled at 3-hourly intervals by CESM, CMAM, DEHM, EMEP MSC-W, GEM-MACH, GEOS-Chem, MATCH, MATCH-SALSA, MRI-ESM2, UKESM1, and WRF-Chem for the years 2008, 2009, 2014, and 2015. The comparisons focus on the troposphere (0–7 km partial columns) at Eureka, Canada; Thule, Greenland; Ny Ålesund, Norway; Kiruna, Sweden; and Harestua, Norway. Overall, the models are biased low in the tropospheric column, on average by −9.7 % for CH4, −21 % for CO, and −18 % for O3. Results for CH4 are relatively consistent across the 4 years, whereas CO has a maximum negative bias in the spring and minimum in the summer and O3 has a maximum difference centered around the summer. The average differences for the models are within the FTIR uncertainties for approximately 15 % of the model–location comparisons.

A key functionality for cleansing wipes is their efficiency in removing dirt and microbial contamination from the skin to safe or non-detectable levels, traditionally determined using the gravimetric method, which has been reported to be prone to experimental errors. This study evaluates the efficiency of a water-based cleansing wipe, WaterWipes® (WaterWipes, UC, Drogheda, Ireland), for removing synthetic faecal matter (FecloneTM, SiliClone Creations LLC, Havertown, PA, United States) and Escherichia coli (NCTC 10538) from volunteers’ skin, the former using a dermal analytical device called the Antera 3DTM camera (Miravex Ltd., Dublin, Ireland), and the latter using standard microbiological methods. FecloneTM was applied to participants’ forearms and the Antera 3DTM camera captured detailed images of the skin surface before and after wiping. The Antera 3DTM camera approach was found to be effective in measuring cleaning efficiency, with the wipe removing all detectable traces of the FecloneTM applied. The total pore area (mm2), pore count, and total pore volume (mm3) in test participants post-wiping were observed to be reduced on average by 39.05%, 34.39%, and 39.98%, respectively. The wipe removed 99.99% of E. coli (NCTC 10538) applied, as measured using the microbial plate count method. In conclusion, the Antera 3DTM camera method was observed to be effective in evaluating removal of topically applied FecloneTM.

This paper discusses the iteration of a seismic retrofit solution for shear-deficient end regions of 19 reinforced concrete (RC) moment-resisting frame (MRF) T-beams located in a 12-story RC MRF building in downtown Los Angeles, California. Local strengthening with externally bonded (EB) fiber-reinforced polymer (FRP) fabric was chosen as the preferred retrofit strategy due to its cost-effectiveness and proven performance. The FRP-shear-strengthening scheme for the deficient end-hinging regions of the MRF beams was designed and evaluated through large-scale cyclic testing of three replica specimens. The specimens were constructed at 4/5 scale and cantilever T-beam configurations with lengths of 3.40 m or 3.17 m. The cross-sectional geometry was 0.98 × 0.61 m with a top slab of 1.59 m in width and 0.12 m in thickness. Applied to these specimens were three different retrofit configurations, tested sequentially, namely: (a) unanchored continuous U-wrap; (b) anchored continuous U-wrap with conventional FRP-embedded anchors at the ends; and (c) fully closed external FRP hoops made of discrete FRP U-wrap strips and FRP through-anchors that penetrate the top slab and connect both ends of the FRP strips, combined with intermediate crack-control joints. The strengthening concept with FRP hoops precluded the premature debonding and anchor pullout issues of the two more conventional retrofit solutions and, despite a more challenging and labor-intensive installation, was selected for the in-situ implementation. The proposed hooplike EB-FRP shear-strengthening scheme enabled the deficient MRF beams to overcome a 30% shear overstress at the end-yielding region and to develop high-end rotations (e.g., 0.034 rad [3.4% drift] at peak and 0.038 rad [3.8% drift]) at strength loss for a beam that, otherwise, would have prematurely failed in shear. These values are about 30% larger than the ASCE 41 prescriptive value for the Life Safety (LS) performance objective. Energy dissipation achieved with the fully closed scheme was 108% higher than that of the unanchored FRP U-wrap and 45% higher than that of the FRP U-wrap with traditional embedded anchors. The intermediate saw-cut grooves successfully attracted crack formation between the strips and away from the FRP reinforcement, which contributed to not having any discernable debonding of the strips up to 3% drift. This paper presents the experimental evaluation of the three large-scale laboratory specimens that were used as the design basis for the final retrofit solution.

Postural imbalance is a leading cause of injury in older adults. Our study investigated the effectiveness of virtual reality (VR)-based interventions on balance ability in this population. Here, we examined 21 older, healthy adults (75.8 ± 5.2 years old). Participants performed 6 weeks of balance training, twice per week for 30 min; the experimental group donned an Oculus VR headset during the training while control participants did not. To assess balance ability, a force platform measured displacement of the center of pressure (COP) during quiet standing in double-leg, tandem, and single-leg stances with eyes closed pre- and post-assessment. COP measurements included mediolateral (ML) and anterior–posterior (AP) directions for root mean square (RMS), peak-to-peak displacement (MAXD), total excursion (TE), and 95% confidence area ellipse (AE) parameters. Post-training assessments showed improvements (significant decreases) in the COP parameters. Control group COP parameters improved in various stances ranging from a 3% to 40% decrease on average. The VR group improved MAXD, TE, and 95% AE ranging from a 5% to 47% decrease, on average, across various stances post- compared to pre-training. VR-based exercise training programs may encourage older adults to engage in mobility exercises, leading to a reduced risk of falls or injuries.

In the summer of 2018, Europe experienced an intense heatwave which coincided with several persistent large-scale ozone (O3) pollution episodes. Novel satellite data of lower-tropospheric column O3 from the Global Ozone Monitoring Experiment-2 (GOME-2) and Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite showed substantial enhancements in 2018 relative to other years since 2012. Surface observations also showed ozone enhancements across large regions of continental Europe in summer 2018 compared to 2017. Enhancements to surface temperature and the O3 precursor gases carbon monoxide and methanol in 2018 were co-retrieved from MetOp observations by the same scheme. This analysis was supported by the TOMCAT chemistry transport model (CTM) to investigate processes driving the observed O3 enhancements. Through several targeted sensitivity experiments we show that meteorological processes, and emissions to a secondary order, were important for controlling the elevated O3 concentrations at the surface. However, mid-tropospheric (∼ 500 hPa) O3 enhancements were dominated by meteorological processes. We find that contributions from stratospheric O3 intrusions ranged between 15 %–40 %. Analysis of back trajectories indicates that the import of O3-enriched air masses into Europe originated over the North Atlantic, substantially increasing O3 in the 500 hPa layer during summer 2018.