Lower Lifetime Research Articles

Access to cardiac PET/CT by sarcoidosis patients and cost-effectiveness analysis of cardiac PET/MR compared to the standard of care

ImportanceCardiac sarcoidosis is associated with a high mortality rate. Given multiple barriers to obtaining cardiac PET imaging, we suspect individuals with access to this imaging modality are not representative of the Sarcoid patient population, which in the United States are predominantly Black females. ObjectiveTo evaluate the demographics of patients with cardiac PET access and the cost-effectiveness of cardiac PET/MR imaging relative to standard of care. DesignThis is a retrospective, observational study. The demographic information of patients with suspected cardiac sarcoidosis and cardiac PET/CT imaging within a national registry of sarcoidosis were reviewed (n = 4561). An individual-level, continuous, time-state transition model was used for the evaluation of long-term cost-effectiveness for the combined cardiac PET/MR compared to standard of care cardiac MR followed by cardiac PET/CT. ResultsPatients who underwent cardiac PET in the national registry had 88.35% higher odds of being male (p < 0.001) and 43.82% higher odds of being White (p = 0.003) than their counterparts who did not have cardiac PET imaging. Combined cardiac PET/MR had overall lower total lifetime costs ($8761 vs $10,777) and overall improved expected quality of life-years compared to the standard of care (0.77 vs 0.69). Conclusion and relevanceThe findings suggest that patients with access to cardiac PET/CT are not representative of the patient population most likely to have cardiac sarcoidosis in this limited study evaluation. Universal insurance coverage should be considered for Cardiac PET imaging as same day cardiac PET and MR imaging has potential long-term cost and quality of life benefit.

Research of Single-Event Burnout in 1.2-kV Rated CoolSiC Trench MOSFET

This paper presents the two-dimensional (2-D) numerical simulation results of heavy-ion induced reverse drain current degradation and single-event burnout (SEB) in the 1.2-kV rated CoolSiC Trench metal-oxide-semiconductor field-effect transistor (MOSFET). The physics models employed in simulations and critical failure conditions were validated by the heavy-ion irradiation experiments of the commercially available 1.2-kV rated SiC planar-gate MOSFET devices. The CoolSiC Trench MOSFET was proven to behave comparative SEB performance compared with the SiC planar-gate MOSFET. The robustness of the CoolSiC Trench MOSFET with different single buffer layer (SBL) designs against a heavy ion was simulated. Furthermore, the SBL-CoolSiC Trench MOSFET with low carrier lifetime control was investigated. According to the simulation results, the severe degeneration failure tolerance increased to 800 V; the SEB failure tolerance could reach 900 V.

Characterisation of striations in n-type silicon wafer processed with polysilicon contacts

We analysed the electronic and optical properties of oxygen-related striations in n-type Czochralski silicon wafers that underwent polysilicon contact process using deep level transient spectroscopy and micro-photoluminescence. Band to band micro-photoluminescence spectra measured at low temperature (80 K) indicate that the dark striations with low lifetime originate from nano-scale oxygen precipitates. Deep level transient spectroscopy results indicate that such nano-scale precipitates cannot be considered as point defects and analysed with Shockley-Read-Hall recombination statistics, but must be treated as extended defects with a continuous spectrum of energies.

Costs of biomarker testing among patients with metastatic lung or thyroid cancer in the USA: a real-world commercial claims database study

ObjectiveThis real-world retrospective database study quantified the costs of biomarker testing in a US population of patients with lung or thyroid cancers.Materials and methodsThe commercial claims IBM Marketscan database, a de-identified real-world dataset, was used to identify patients diagnosed with lung or thyroid cancer between 1/2015 and 12/2019. Eligible patients were 18 years or older with two or more lung or thyroid diagnosis codes. Patients were excluded who had evidence of prior cancer diagnoses. Subgroup analyses evaluated eligible patients with metastatic disease. Descriptive statistics were used to evaluate commercial insurance plan payer and patient out-of-pocket costs for diagnostic testing overall as well as by test procedure code and payer type. Costs were adjusted to 2020 US dollars.ResultsA total of 23,633 patients with lung cancer were eligible, 13,320 of whom had metastatic disease. There were 36,867 patients with thyroid cancer, 2,241 of whom had metastatic disease. Biomarker codes were observed among 68.4/75.8% (lung/metastatic lung) and 18.2/42.3% (thyroid/metastatic thyroid). Few patients had codes for comprehensive biomarker tests (5.2/6.7% lung/metastatic lung, 0.3/2.2% thyroid/metastatic thyroid) Among those with biomarker tests, the median per-patient total payer lifetime costs of all biomarker testing were $394/$462 (lung/metastatic lung) and $148/$232 (thyroid/metastatic thyroid). Total lifetime biomarker costs for payers ranged from a median of $128 (consumer-driven health plans) to $477 (preferred provider organizations). Median lifetime patient out-of-pocket costs were $0.00 for both tumor types and all payer types except for consumer-driven health plans ($12 for thyroid and $10 for metastatic lung).ConclusionsWhile comprehensive testing adds to the cost of biomarker testing, these data suggest the relatively low lifetime cost of biomarker testing for both payers and patients. Costs for biomarker testing should not be a limitation to access among these populations with commercial insurance plans in the US.

Fluoroalkoxyaluminate-based ionic liquids as electrolytes for sodium-ion batteries

Ionic liquids (ILs) are a promising class of materials because of their unique properties such as high electrochemical stability window and intrinsic conductive nature, which are desirable in the development of high-performance electrolytes for energy storage applications. However, the strong Coulombic interactions between cation and anion, which contributes to the high viscosity of the ILs, are the main bottleneck in their applications as electrolytes. Weakly coordinated anions-based ILs are a class of electrolytes with high degree of charge delocalization, which leads to weak ionic interactions and improves the ionic transport. Here, we have performed molecular dynamics simulations and density functional theory calculations of imidazolium and ammonium-based ionic liquids in different Na+ mole fractions comprising the weakly coordinated fluoroalkoxyaluminate anion ([Al(Ohfip)4]−). The results have shown that the 0.8-scaled OPLS-AA based force field predicted the transport properties of neat systems with good accuracy. The Na+-[anion] pair structural and lifetime analysis suggest that the fluoroalkoxyaluminate promotes lower lifetimes and facilitates the mobility of Na+ in these systems. Although the cations provided similar transport and structural results for Na+, the theoretical electrochemical stability windows of the ammonium-derived ILs exhibited values above 5.0 eV, which indicates good performance for energy storage applications.

Association of fasting plasma glucose trajectory with lifetime risk of cardiovascular disease.

Few studies have used multiple measurements of fasting plasma glucose (FPG) to examine the impact of long-term FPG trajectory patterns on lifetime risk of cardiovascular disease (CVD). We aimed to identify the long-term patterns in FPG trajectories and to estimate the lifetime risk of CVD according to FPG trajectories. Individuals free of CVD at index ages 35 (n = 72,324), 45 (n = 62,049), and 55 (n = 38,113) years were included. FPG concentrations were measured in 2006, 2008, and 2010. The FPG trajectories were identified by latent mixture modeling. The modified Kaplan-Meier method was used to calculate lifetime risk of CVD. We identified five distinct FPG trajectories and named them according to FPG range and changing pattern over time: low-stable, moderate-stable, moderate-increasing, elevated-decreasing, and elevated-stable. At index age 35 years, we documented 3110 CVD events in men during 371,219 person-years of follow-up and 357 CVD events in women during 107,447 person-years of follow-up. Among all participants, the elevated-stable FPG pattern experienced the highest lifetime risk of CVD (44.8%, 95% CI: 37.8-51.9%), low-stable pattern was lowest (24.3%, 95% CI: 23.3-25.2%). At index age 55 years, although the elevated-stable and elevated-decreasing FPG patterns had similar original FPG concentrations, individuals with elevated-decreasing pattern (30.0%, 95% CI: 23.9-36.1%) had approximately one-third less lifetime risk of CVD than those with elevated-stable pattern (43.6%, 95% CI: 31.8-55.3%). FPG trajectories were significantly associated with the lifetime risk of CVD. Both decrease in FPG over time and consistently lower FPG over 4 years were associated with lower lifetime risk of CVD.

Acetylides for the Preparation of Phosphorescent Iridium(III) Complexes: Iridaoxazoles and Their Transformation into Hydroxycarbenes and N,C(sp3),C(sp2),O-Tetradentate Ligands.

The preparation of three families of phosphorescent iridium(III) emitters, including iridaoxazole derivatives, hydroxycarbene compounds, and N,C(sp3),C(sp2),O-tetradentate containing complexes, has been performed starting from dimers cis-[Ir(μ2-η2-C≡CR){κ2-C,N-(MeC6H3-py)}2]2 (R = tBu (1a), Ph (1b)). Reactions of 1a with benzamide, acetamide, phenylacetamide, and trifluoroacetamide lead to the iridaoxazole derivatives Ir{κ2-C,O-[C(CH2tBu)NC(R)O]}{κ2-C,N-(MeC6H3-py)}2 (R = Ph (2), Me (3), CH2Ph (4), CF3 (5)) with a fac disposition of carbons and heteroatoms around the metal center. In 2-methyltetrahydrofuran and dichloromethane, water promotes the C-N rupture of the IrC-N bond of the iridaoxazole ring of 3-5 to form amidate-iridium(III)-hydroxycarbene derivatives Ir{κ1-N-[NHC(R)O]}{κ2-C,N-(MeC6H3-py)}2{═C(CH2tBu)OH} (R = Me (6), CH2Ph (7), CF3 (8)). In contrast to 1a, dimer 1b reacts with benzamide and acetamide to give Ir{κ4-N,C,C',O-[py-MeC6H3-C(CH2-C6H4)NHC(R)O]}{κ2-C,N-(MeC6H3-py)}(R = Ph (9), Me (10)), which bear a N,C(sp3),C(sp2),O-tetradentate ligand resulting from a triple coupling (an alkynyl ligand, an amide, and a coordinated aryl group) and a C-H bond activation at the metal coordination sphere. Complexes 2-4 and 6-10 are emissive upon photoexcitation, in orange (2-4), green (6-8), and yellow (9 and 10) regions, with quantum yields between low and moderate (0.01-0.50) and short lifetimes (0.2-9.0 μs).

Transport characteristics and lattice dynamics with phonon topology accentuation in layered CuTlX (X: S, Se)

In recent years, numerous Cu-based compounds have attracted a great deal of interest for enhanced thermoelectric energy conversion. Here, we demonstrate that CuTlX (X: S, Se), a layered semiconductor, exhibits low lattice thermal conductivity (κ l ) and a high thermoelectric figure of merit (ZT), using density functional theory calculations and Boltzmann transport theory beyond relaxation time approximation. To evaluate the absolute values of thermoelectric coefficients, different scattering mechanisms such as acoustic deformation potential scattering, impurity phonon scattering, and polar optical phonon scattering are analysed. This low lattice thermal conductivity, which is complemented by a low group velocity and a low phonon lifetime, accounts for the remarkable thermoelectric efficiency in these compounds. In CuTlS, the contribution of the in-plane optical phonon mode to κ l results in a decrease in its value, which might be attributed to the occurrence of Dirac-like crossings with non-trivial topological characteristics, as corroborated by the non-zero Berry curvature value. Overall, the thermoelectric behavior of both compounds is favorable at ambient temperature. Specifically, the out-of-plane direction in CuTlSe presents elevated thermoelectric performance with a high value for the thermoelectric figure of merit, with 1.08 and 1.16 for holes and electrons, respectively, at 300 K at the optimal carrier density of 1019 cm−3 , which well aids in both the electron and phonon transport. We also undertook monolayer examinations of these compounds due to the existence of van der Waals interactions, which predicted strong thermoelectric performance for both carrier concentrations at 300 K. As a result, our study presents a theoretical prediction on transport phenomena that requires experimental verification and should motivate additional research into prospective thermoelectric materials in the same crystal family for device applications.

Theoretical analysis of the thermoelectric properties of penta-PdX2 (X = Se, Te) monolayer.

Based on the successful fabrication of PdSe2 monolayers, the electronic and thermoelectric properties of pentagonal PdX2 (X = Se, Te) monolayers were investigated via first-principles calculations and the Boltzmann transport theory. The results showed that the PdX2 monolayer exhibits an indirect bandgap at the Perdew-Burke-Ernzerhof level, as well as electronic and thermoelectric anisotropy in the transmission directions. In the PdTe2 monolayer, P-doping owing to weak electron-phonon coupling is the main reason for the excellent electronic properties of the material. The low phonon velocity and short phonon lifetime decreased the thermal conductivity (κ l) of penta-PdTe2. In particular, the thermal conductivity of PdTe2 along the x and y transmission directions was 0.41 and 0.83Wm-1K-1, respectively. Owing to the anisotropy of κ l and electronic structures along the transmission direction of PdX2, an anisotropic thermoelectric quality factor ZT appeared in PdX2. The excellent electronic properties and low lattice thermal conductivity (κ l) achieved a high ZT of the penta-PdTe2 monolayer, whereas the maximum ZT of the p- and n-type PdTe2 reached 6.6 and 4.4, respectively. Thus, the results indicate PdTe2 as a promising thermoelectric candidate.

A Novel Way to Fill Green Gap of GaN-Based LEDs by Pinning Defects in Nanorod Array.

Nanorod array and planar green-emission InGaN/GaN multi-quantum well (MQW) LEDs were fabricated by lithography, nano-imprinting, and top-down etching technology. The defect-pinning effect of the nanostructure was found for the first time. The ratio of the bright regions to the global area in the panchromatic CL images of green MQW samples increased from 30% to about 90% after nano-fabrication. The overall luminous performance significantly improved. Throughout temperature-dependent photoluminescence (TDPL) and time-resolved PL (TRPL) measurements, the migration and recombination of carriers in the MQWs of green LEDs were analyzed. It was proved that nanostructures can effectively prevent carriers from being captured by surrounding nonradiative recombination centers. The overall PL integral intensity can be enhanced to above 18 times. A much lower carrier lifetime (decreasing from 91.4 to 40.2 ns) and a higher internal quantum efficiency (IQE) (increasing from 16.9% to 40.7%) were achieved. Some disputes on the defect influence were also discussed and clarified.

A novel electromagnetic microactuator with a stainless steel mas-spring structure

Microactuators are one of the main components of the microelectromechanical and microfluidic systems and play a key role in their development. Many such systems, e.g. micropumps and microvalves, utilize an electromagnetic microactuator with a displacement range of a few micrometers traversed within a few seconds. Most of the electromagnetic microactuators have low lifetime and fracture toughness or low recovery speed. Microactuators with metallic mass-spring structure can overcome the mentioned disadvantages or limitations. This paper presents the design and fabrication of a novel stainless steel electromagnetic microactuator fabricated using micro-wire electrical discharge machining. The microactuator in question consists of a mass-and-spring structure made of 304 stainless steel, a permanent magnet made of NdFeB, and a microcoil. The impacts of the number of turns, distance, and electric current on the magnetic field of the microcoil and the displacement of the microactuator membrane with time have been investigated to determine the microactuator characteristics. The results indicated a displacement of about ±10 (20) μm within 7 s for an electric current of 1100 mA. This microactuator exhibits a faster response compared to the similar microactuators. Consequently, it can be used at higher operating frequencies and, thus, improves the fluid flow in micropumps.

Links between defect chemistry, conduction, and lifetime in heavily Nb doped lead zirconate titanate films

Phase pure PbZr0.52Ti0.48O3 (PZT) films with up to 13 mol. % Nb were prepared on Pt-coated Si substrates using chemical solution deposition; charge compensation for Nb was accomplished by reducing the concentration of lead in the film. For high Nb doping levels, (1) superoxidation of the PZT film surface makes the PZT/Pt interface more p-type and, hence reduces electron injection over the Schottky barrier, (2) the bulk charge transport mechanism changes from electron trapping by Ti4+ to hole migration between lead vacancies, and (3) the ionic conductivity due to migration of oxygen vacancies decreases. For ≤6 mol. % Nb, electrical degradation was controlled via field-induced accumulation of oxygen vacancies near the cathode, which, in turn, leads to Schottky barrier lowering and electron trapping by Ti4+. In phase pure 13 mol. % Nb doped PZT films, on the other hand, the increase in the leakage current during electrical degradation was dominated by hole migration between lead vacancies (2[VPb″]∼[h•]). A much lower lifetime and drastic increase in the leakage current upon electrical degradation was observed in mixed phase PNZT films, which was attributed to (1) a more electrically conductive pyrochlore phase and (2) a high concentration of lead vacancies.

Re-evaluating the health impact and cost-effectiveness of tuberculosis preventive treatment for modern HIV cohorts on antiretroviral therapy: a modelling analysis using data from Tanzania

BackgroundIsoniazid preventive therapy (IPT) can prevent tuberculosis among people receiving antiretroviral therapy (ART). HIV programmes are now initiating patients on ART with higher average CD4 cell counts and lower tuberculosis risks under test-and-treat guidelines. We aimed to investigate how this change has affected the health impact and cost-effectiveness of IPT.MethodsWe constructed a tuberculosis–HIV microsimulation model parameterised using data from a large HIV treatment programme in Dar es Salaam, Tanzania. We simulated long-term health and cost outcomes for the 211 748 individuals initiating ART between Jan 1, 2014, and Dec 31, 2020, under three scenarios: no IPT access; observed levels of IPT access (75%) and completion (71%); and full (100%) IPT access and completion. We stratified results by ART initiation year and starting CD4 cell count.FindingsObserved levels of IPT access were estimated to have averted 12 800 (95% uncertainty interval 7300 to 21 600) disability-adjusted life-years (DALYs) and saved US$23 000 (–2 268 000 to 1 388 000). Full IPT access would have averted 24 500 (15 100 to 38 300) DALYs and cost $825 000 (–1 594 000 to 4 751 000), equivalent to $23·4 per DALY averted. Lifetime health benefits of IPT were estimated to be greater for more recent ART cohorts, while lifetime costs were stable. In subgroup analyses, a higher CD4 cell count at ART initiation was associated with greater health gains from IPT (15 900 [10 300 to 22 500] DALYs averted by full IPT per 100 000 patients for CD4 count >500 cells per μL at ART initiation, versus 7400 [4500 to 11 600] for CD4 count <100 cells per μL) and lower incremental lifetime costs.InterpretationIPT remains highly cost-effective or cost-saving for recent ART cohorts. The health impact and cost-effectiveness of IPT are estimated to improve as patients initiate ART earlier in the course of infection.FundingUS National Institutes of Health.

Effects of metal impurities at the edges of cast Si ingot on crystal quality and solar cell performance

In this study, the effects of metal impurity diffusion at the edges of cast crystalline Si on crystal quality and solar cell performance were investigated and analyzed. The metal impurity diffusion resulted in a decrease of the minority carrier lifetime within Si crystal, low luminous intensity in photoluminescence (PL) images for wafers, high density leakage points in electroluminescent (EL) images and the decrease of photoelectric conversion efficiency(η) for solar cells. The study reveals that the region of low minority carrier lifetime (i.e., red-zone) in Si wafers can be narrowed down by using annealing treatment, in a temperature range of 500–600 °C. However, the annealing treatment on Si wafers had little effect on the efficiency of solar cells. A novel slicing direction for Si wafers, along to the crystal orientation (ACO), allowed the fabrication of Si wafers with non-red zone or with complete red-zone from the same side Si block. The η of the solar cells based on Si wafers with non-red zone was 1.7 % higher than that of the solar cells based on Si wafers with complete red zone. In addition to that, while being sliced from the same side Si block, the mean η of cells, based on wafers from the ACO slicing method was calculated to be 0.11 % higher than that of cells, which based on wafers from the traditional perpendicular crystal orientation (PCO) slicing method.

Bimetallic Electrocatalyst of Hyaluronate-Au@Pt for Durable Oxygen Reduction in Biofuel Cells

Biofuel cells (BFCs) have attracted great attention as battery substitutes in wearable and implantable devices. Oxygen reduction enzymes such as bilirubin oxidase, laccase, and peroxidase are used as cathodic materials in enzymatic BFCs (EBFCs). However, the low power output and short lifetime of EBFCs have limited their further commercial applications. Here, a bimetallic electrocatalyst of hyaluronate-Au@Pt (HA-Au@Pt) was synthesized to enhance the oxygen reduction reaction (ORR) performance of EBFCs by modifying the electronic structure of Pt with high oxygen reduction. HA is a biocompatible, hydrophilic, and linear polysaccharide, which can be utilized as a binder and stabilizer to enhance the dispersibility, stability, and biocompatibility of Au@Pt for wearable and implantable devices. The open circuit voltage is 0.35 V and the maximum current density is −166 μA/cm2 at −0.04 V for the optimized HA-Au@Pt electrocatalyst with 0.5 mM H2PtCl6. In comparison with other biocompatible polymers, HA in HA-Au@Pt catalysts showed excellent dispersibility and remarkable durability under the ORR condition. The power density of a glucose oxidase-based EBFC appeared to be 15.8 μW/cm2 at 0.29 V, demonstrating the feasibility of HA-Au@Pt as a promising electrocatalyst in the energy generation of EBFCs.

Nickel Cobalt Oxide Decorated Cerium Oxide Nanorods for Polysulfide Trapping and Catalytic Conversion in Advanced Lithium Sulfur Batteries

Lithium sulfur batteries (LSBs) are promising candidates for next-generation rechargeable batteries due to the active material sulfur being earth abundant, low cost and environmentally friendly element. But the most important feature of LSBs is that the theoretical capacity of sulfur is ~1645 mAh g-1 which is ~5 times higher than the conventional lithium-ion batteries. However, even with these valuable assets, LSB has not yet been commercialized due to the inherent problems of fast capacity loss resulting in low cycle lifetime. This capacity loss originates from the migration of dissolved sulfur discharge products in the electrolyte known as the notorious polysulfide shuttling effect.To deal with this issue, several research efforts have been made to trap the high order lithium polysulfides by a) physically encapsulation using high surface area carbonaceous materials and b) chemically binding the lithium polysulfides in its cathode host. Several materials are very popular to efficiently bind the lithium polysulfides such as transition metal oxides, nitrides, sulfides and have helped making significant advances to long cycle life lithium sulfur batteries. However, to make the transition to design next generation LSBs, there is a need for materials that can facilitate fast polysulfide conversion by catalytic reaction that will reduce the diffusion and agglomeration of polysulfides in the liquid organic electrolyte, resulting in high capacity and long cycle lifetime.With this strategy in mind, we have designed NiCoOx decorated on CeO2 nanorods support as cathode host material for LSBs to provide dual adsorption-catalysis synergy. The CeO2 nanorods with enriched surface defects can effectively bind the lithium polysulfides whereas the NiCoOx nanoclusters can provide highly efficient electrocatalytic sites to improve the conversion kinetics of elemental sulfur to high order lithium polysulfides to finally the lower order polysulfides. As a result, the derived LSBs exhibited excellent electrochemical performance with high capacity of 1236 mAh g-1 at 0.2C with a sulfur loading of 1.33 mg cm-2. Even with high sulfur loading 2.66 mg cm-2 the LSBs exhibits 755 mAh g-1 at 0.2C with a capacity decay of only 0.08% per cycle after 170 cycles. The battery also operates at the sulfur loading of 4 mg cm-2 and 5.33 mg cm-2 for more than 100 which is convincing considering commercialization of LSB. Key words: lithium sulfur batteries, lithium polysulfides, shuttle effect, cerium oxide, catalysis.

(Invited) Crystal Engineering of Bismuth Vanadate for Enhanced Light-Driven Water Oxidation

Photocatalytic and photoelectrochemical processes employing photoactive semiconductors are two key systems in harvesting sunlight for energy and environmental applications. Strategies have been formulated to improve the properties of the semiconductor for better performances. However, requirements to yield excellent performances are different in these two distinctive systems. Understanding of the underlying mechanism for the photoexcited charge transportation in relation to their photoactivities is of fundamental importance for rational design of high-performing photoactive materials, which may serve as a useful guideline for the fabrication of good photocatalysts or photoelectrodes toward sustainable solar fuels generation. Many photoactive semiconductors, including bismuth vanadate, are having inadequate charge transport properties such as low charge mobility, short lifetime, and slow surface kinetics. Standalone single photoactive semiconductors also faces the challenge of meeting the needs for large redox potentials with a sufficiently narrow bandgap for visible light absorption. Coupling two or more components into a photoactive composite may address some of these drawbacks by utilizing the strengths of the individual semiconductors. In this presentation, the charge transportation behavior of single component photoactive semiconductor based on bismuth vanadate, and the composite materials forming heterojunction with bismuth vanadate, will be examined and discussed (example of modulation of BiVO4 photocatalyst in Figure 1 ).1 Typically, crystal facet engineering, interfacing with non-photoactive secondary component, and narrowing the crystal size into quantum-confinement region, will be the three strategies to be shared with audience during the presentation. Preferential charge migration depending on the crystal facet has been reported in various photocatalysts. These promoted charge migration can be further boosted with spatially deposited cocatalysts on the selective redox sites. The manipulation of crystal facet allows the controlled electron transfer to induce 4-electron process (oxygen evolution) or 2-electron process (hydrogen peroxide evolution) in water oxidation. Nanosizing the bismuth vanadate into <10 nm region with distinctive yet interconnected crystal domains leads to the expansion of band structure. Conduction band of bismuth vanadate was expanded to energetic level capable of reducing proton into H2. The traditional O2-evolving bismuth vanadate is now demonstrating H2-producing properties. Figure 1: Time-resolved microwave conductivity (TRMC) spectroscopy signals measured for BiVO4 and its Power-law decay fittings.Reference1. H. Wu, R. Irani, K. Zhang, L. Jing, H. Dai, H. Y. Chung, F. F. Abdi, Y. H. Ng*, Unveiling Carrier Dynamics in Periodic Porous BiVO4 Photocatalyst for Enhanced Solar Water Splitting. ACS Energy Lett. 2021, 6, 3400-3407. Figure 1

Simulation of Cathode Catalyst Durability Under Fuel Cell Vehicle Operation - the Effect of Temperature

Fuel cell vehicles (FCVs) emerge to be promising candidates to produce clean power for the transportation sector in order to tackle climate change issues. Although the commercialization of polymer electrolyte membrane fuel cells (PEMFCs) has progressed in the past few decades, there are still obstacles to address, including high cost and limited hydrogen infrastructure. For heavy duty transportation applications, the PEMFC durability is also not yet proven, and extrapolating from lab data to real-world field operating conditions remains a significant challenge [1].In this work, the cathode catalyst degradation in PEMFCs is studied to make an estimation of fuel cell durability in the FCV application. The well-known Butler-Volmer approach is utilized to model platinum dissolution and redeposition, platinum oxidation and platinum ion formation during the fuel cell operation [2]. First, the model is calibrated with the results presented by Ferreira et al. [3] at 80℃; the calibrated model is then validated with Kocha’s results [4] to demonstrate the model’s capability of generating reliable results at different temperatures. In order to realistically predict the cathode degradation pattern and lifetime, the real-life fuel cell operating conditions should be obtained. Therefore, a drive cycle recorded based on a real-life transit bus operation in the city of Victoria is utilized to calculate the input fuel cell voltage profile. The procedure to calculate fuel cell operating voltage profile using the drive cycle has been thoroughly explained by Ahmadi and Kjeang [5]. This procedure employs Newton’s second law to calculate the required cell power density considering the air flow drag force counteracting the vehicle thrust. Finally, polarization curves representing the fuel cell performance are used to calculate the fuel cell voltage profile with the determined required cell power density. Polarization curves measured under a range of temperatures are employed to adequately reflect the effect of temperature on the fuel cell performance. The cell active area is considered to be 500 cm2 and the stack is assumed to contain 225 cells, representing a nominal stack power of 74 kW at 80℃. The fuel cell operation and degradation are simulated at three different temperatures: 60, 70, and 80℃. The change of remaining electrochemically active surface area (ECSA) with time is calculated as the output of the model.Temperature highly affects the electrochemical reactions of platinum dissolution in several ways. First, it affects the Tafel slope in the platinum dissolution reaction. Second, it substantially impacts on platinum degradation reaction rate constant [6]. The Arrhenius approach is taken in this study to apply the effect of temperature on the reaction rate constants. Fuel cell voltage loss over time is determined by assuming simple Tafel kinetics. The cathode lifetime is calculated at 0.6 A/cm2 and is estimated by considering 10% voltage drop as the failure criterion. Fig. 1 shows the simulated change of remaining ECSA over time and the resulting fuel cell lifetime for the three different cell temperatures. The results indicate that the cathode lifetime increases 168% when the cell temperature drops from 80℃ to 60℃ due to a significantly lower platinum degradation rate at 60℃. The results show relatively low cathode catalyst lifetimes for a transit bus. The reason is attributed to the bus drive cycle used as the model input. The drive cycle contains a great portion of deceleration and idling time which leads to a fuel cell operation close to open circuit voltage (OCV), thus experiencing a high degradation rate.In this regard, the present modeling framework could become a useful tool for fuel cell and FCV developers to predict lifetime for new products and systems prior to commercial release. Scientifically, the present model can also be used to further explore key influencing factors on fuel cell durability and develop more durable cell, stack, and system designs for a targeted FCV application. Acknowledgements This research was supported by the Natural Sciences and Engineering Research Council of Canada, Canada Research Chairs, and Simon Fraser University Community Trust Endowment Fund.

Lifetime Predicted Risk of Atherosclerotic Cardiovascular Disease Among an Urban Cohort

Introduction: Although atherosclerotic cardiovascular disease (ASCVD) results have significantly improved in recent years, ASCVD continues to be the world's leading cause of morbidity and mortality. Therefore, in the present study, lifetime risk of ASCVD was calculated in an urban cohort. White-collar employees have higher risk of developing cardiovascular disease events because of their work profile. Aim and Objectives: To calculate lifetime predicted risk of ASCVD among study cohort and to explore factors contributing to the disparities of cardiovascular risks. Materials and Methods: This was community-based cross-sectional study. The baseline data were collected during the period 2016–2019 from Rajkot city, and their lifetime predicted risk of ASCVD was calculated using ASCVD risk calculator. Crude and adjusted prevalence ratio was calculated. Results: The study revealed that 69.25% and 6.37% of participants had low and intermediate lifetime predicted risk of ASCVD, respectively, while the remaining 16.12% and 8.25% had borderline and high risk, respectively. Conclusion: This study indicates that increased lifetime predicted risk of ASCVD was associated with increasing age, male, stress, elevated blood pressure, high level of body mass index, and central obesity among participants.

Lifetime Earnings in the United States over Six Decades

Between the 1957 and 1983 labor market entry cohorts, median lifetime earnings declined by 10–19 percent for men and increased by 22–33 percent for women, albeit relative to very low median lifetime earnings for the early cohorts. The difference between newer and older cohorts comes from differences in median earnings at the time of labor market entry. Inequality in lifetime earnings has increased significantly within each gender group, but the closing lifetime gender gap has kept overall lifetime inequality flat. The increase among men is largely attributable to subsequent cohorts entering the labor market with progressively higher levels of inequality. (JEL D15, J16, J31, J32)