Exposure to ambient fine particulate matter (PM) is a leading risk factor for the global burden of disease. However, uncertainty remains about PM sources. We use a global chemical transport model (GEOS-Chem) simulation for 2014, constrained by satellite-based estimates of PM to interpret globally dispersed PM mass and composition measurements from the ground-based surface particulate matter network (SPARTAN). Measured site mean PM composition varies substantially for secondary inorganic aerosols (2.4-19.7 μg/m), mineral dust (1.9-14.7 μg/m), residual/organic matter (2.1-40.2 μg/m), and black carbon (1.0-7.3 μg/m). Interpretation of these measurements with the GEOS-Chem model yields insight into sources affecting each site. Globally, combustion sectors such as residential energy use (7.9 μg/m), industry (6.5 μg/m), and power generation (5.6 μg/m) are leading sources of outdoor global population-weighted PM concentrations. Global population-weighted organic mass is driven by the residential energy sector (64%) whereas population-weighted secondary inorganic concentrations arise primarily from industry (33%) and power generation (32%). Simulation-measurement biases for ammonium nitrate and dust identify uncertainty in agricultural and crustal sources. Interpretation of initial PM mass and composition measurements from SPARTAN with the GEOS-Chem model constrained by satellite-based PM provides insight into sources and processes that influence the global spatial variation in PM composition.

Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM2.5) are important for understanding potential health impacts, prioritizing air pollution mitigation strategies, and enabling global chemical transport model development. PM2.5 filter samples (N ~ 800 from 19 locations) collected from a globally distributed surface particulate matter sampling network (SPARTAN) between January 2013 and April 2019 were analyzed for particulate mass and trace metals content. Metal concentrations exhibited pronounced spatial variation, primarily driven by anthropogenic activities. PM2.5 levels of lead, arsenic, chromium, and zinc were significantly enriched at some locations by factors of 100–3000 compared to crustal concentrations. Levels of metals in PM2.5 and PM10 exceeded health guidelines at multiple sites. For example, Dhaka and Kanpur sites exceeded the US National Ambient Air 3-month Quality Standard for lead (150 ng m−3). Kanpur, Hanoi, Beijing and Dhaka sites had annual mean arsenic concentrations that approached or exceeded the World Health Organization’s risk level for arsenic (6.6 ng m−3). The high concentrations of several potentially harmful metals in densely populated cites worldwide motivates expanded measurements and analyses.

Crystalline and nanocrystalline NiSi 2 were studied as negative electrode materials in Li cells. Crystalline NiSi 2 was found to be inactive toward lithiation/delithiation. However, it was found that NiSi 2 becomes active toward lithium when made nanocrystalline by ball milling. X-ray diffraction peaks from nanocrystalline NiSi 2 disappear after the first lithiation process, confirming its electrochemical activity. In subsequent cycles, the voltage curve of nanocrystalline NiSi 2 is similar to that of amorphous Si, excepting that there is significant depression of the lithiation potential, which may arise from internal stress.

Phenolic resin was evaluated as a binder material for Li-ion battery negative electrodes containing Si-based alloys. Phenolic resin was found to have a large first lithiation capacity of about 1200 mAh/g, which is suspected to result from the full reduction of the phenolic resin to form a hydrogen containing carbon. The decomposition products formed during the first lithiation have a reversible capacity of about 400 mAh/g and have excellent properties as a binder for alloy-based negative electrodes. The excellent performance of the phenolic resin combined with its low cost make it very attractive for use as a binder in alloy containing negative electrodes for Li-ion batteries. Furthermore the use of binders that decompose during lithiation represents a new concept in the design of high performance binder materials. As the drive to increase the capacity and energy density of Li-ion batteries continues, much work is focused on finding better electrode materials. Much attention has been given to Si and Si-based alloys because of the obvious benefits of the high theoretical capacity of Si. However, this high capacity comes with a price: the large volume changes during charge/discharge cycling that lead to electrode failure.1 To deal with this problem, many researchers are developing advanced binders. Such binders do not limit the volume expansion experienced during lithiation, but maintain structural integrity and electrical connection to the alloy particles during cycling.2-4 It has been shown that good binders for alloy materials provide good adhesion to the active materials and to the current collector, and also provide complete coverage of the alloy particle surfaces.2 It is suspected that by completely covering the surface of the alloy particles, binders can form an "artificial SEI" layer to reduce electrolyte decomposition reactions.2 Examples of binders that exemplify these properties and result in good cycling performance in alloy negative electrodes include poly(carboxylic acid)s and their alkali metal salts, including carboxymethyl cellulose (CMC), 5-10 poly(acrylic acid) (PAA) 4,[11][12][13] and alginate. 14 Other studies have shown that conductive polymers can also be used as excellent binders for alloy negative electrodes. 15,16 Aromatic polyimides (aro-PI) have been shown to be an excellent binder for alloy negative electrodes. 17,18 Recently, we have shown that aro-PI has a very large first lithiation capacity of 1943 mAh/g, corresponding to a 34 electron reduction process.19 This reduction capacity is consistent with the charge required to fully decompose the aro-PI to a hydrogen containing carbon. The resulting decomposition products also had similar electrochemical properties as hydrogen containing carbon, with a reversible capacity of 874 mAh/g, leading to added electrode capacity. Alloy negative electrodes using aro-PI binder had excellent cycling performance. It was suspected that if a hydrogen containing carbon was formed during the first lithiation, it could provide a conductive framework, ena...

Introduction Financial literacy correlates with less debt and better retirement planning. Medical students, residents, and physicians often have poor financial literacy and large amounts of debt. We measured baseline financial literacy and whether it improved with the administration of a financial literacy course. Methods We created the Medical Mini-MBA,a six-week financial literacy course that targeted gaps in financial literacy among medical students and residents. Weekly topics included personal finance, investing, real estate and mortgage, physician billing and payment models, income and tax, and choosing a medical specialty. A 46-question financial literacy assessment was delivered to participants before and after the course. Results Of the 276 who participated in the course, 179 (64.86%) participated in the study. Participants who completed the course improved their financial literacy score by 10.10/46.00±5.12 (n=93, p<0.001). Self-assessment of financial literacy was positively correlated with financial literacy exam scores (r=0.366, p<0.001). Demographics such as gender, geography, education level, and first-degree relatives who are/were physicians had no effect on financial literacy scores. Conclusions The Medical Mini-MBA improved financial literacy at a Canadian medical school. Implementation of the coursemay equip medical students and residents for financial decisions. It avoids financial conflicts of interest and can supplement the medical curriculum.