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382 results on '"Ward, Zachary"'

2. Sulfur Vacancy Related Optical Transitions in Graded Alloys of MoxW1-xS2 Monolayers

Author

Ghafariasl, Mahdi, Zhang, Tianyi, Ward, Zachary D., Zhou, Da, Sanchez, David, Swaminathan, Venkataraman, Terrones, Humberto, Terrones, Mauricio, and Abate, Yohannes

Subjects
Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

Engineering the electronic bandgap is of utmost importance in diverse domains ranging from information processing and communication technology to sensing and renewable energy applications. Transition metal dichalcogenides (TMDCs) provide an ideal platform for achieving this goal through techniques including alloying, doping, and creating in-plane or out-of-plane heterostructures. Here, we report on the synthesis and characterization of atomically controlled two-dimensional graded alloy of MoxW1-xS2, wherein the center region is Mo rich and gradually transitions towards a higher concentration of W atoms at the edges. This unique alloy structure leads to a continuously tunable bandgap, ranging from 1.85 eV in the center to 1.95 eV at the edges consistent with the larger band gap of WS2 relative to MoS2. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy showed the presence of sulfur monovacancy, VS, whose concentration varied across the graded MoxW1-xS2 layer as a function of Mo content with the highest value in the Mo rich center region. Optical spectroscopy measurements supported by ab initio calculations reveal a doublet electronic state of VS, which was split due to the spin-orbit interaction, with energy levels close to the conduction band or deep in the band gap depending on whether the vacancy is surrounded by W atoms or Mo atoms. This unique electronic configuration of VS in the alloy gave rise to four spin-allowed optical transitions between the VS levels and the valence bands. Our work highlights the potential of simultaneous defect and optical engineering of novel devices based on these 2D monolayers., Comment: 65 pages, 7 figures in main text. 21 figures in supplemental data

Published
2023

3. 'I'm Brazilian, Not Brazilian American': The Experiences of Second-Generation Brazilian Adolescents Preserving Their Heritage Language and Resisting Assimilation

Author

Halpern, Clarisse, Ward, Zachary Austin, and Aydin, Hasan

Abstract

Culture and heritage language (HL) preservation are crucial to developing children of immigrants' ethnic and social identity, creating a sense of belonging, and fostering family and ethnic community support. However, numerous challenges permeate the experiences of underrepresented ethnolinguistic groups like Brazilian immigrants who are largely invisible in the United States. Therefore, this study investigated the lived experiences of second-generation Brazilian adolescents with culture and HL preservation. In-depth interviews and a focus group were conducted with 13 participants. The findings highlighted the participants' embrace of their Brazilian ethnic identity and rejection of their American citizenship, and emphasized HL in affirming their identities and confronting discrimination. [Note: The issue number (1) shown on the PDF is incorrect. The correct issue number for this article is n2.]

Published
2022

9. Vector semi-inner products

Author

Rose, Kyle, Schwanke, Christopher, and Ward, Zachary

Subjects
Mathematics - Functional Analysis
Abstract

We formalize the notion of vector semi-inner products and introduce a class of vector seminorms which are built from these maps. The classical Pythagorean theorem and parallelogram law are then generalized to vector seminorms that have a geometric mean closed vector lattice for codomain. In the special case that this codomain is a square root closed, semiprime $f$-algebra, we provide a sharpening of the triangle inequality as well as a condition for equality.

Published
2021

15. Ranking the efficiency of gas hydrate anti agglomerants through molecular dynamic simulations

Author

Mohr, Stephan, Hoevelmann, Felix, Wylde, Jonathan, Schelero, Natascha, Sarria, Juan, Purkayastha, Nirupam, Ward, Zachary, Acero, Pablo Navarro, and Michalis, Vasileios K.

Subjects
Physics - Chemical Physics
Abstract

Using both computational and experimental methods, the capacity of four different surfactant molecules to inhibit the agglomeration of sII hydrate particles was assessed. The computational simulations were carried out using both steered and non-steered Molecular Dynamics (MD), simulating the coalescence process of a hydrate slab and a water droplet, both covered with surfactant molecules. The experimental work was based on rocking cell measurements, determining the minimum effective dose necessary to inhibit agglomeration. Overall, good agreement was obtained between the performance predicted by the simulations and the experimental measurements. Moreover, the simulations allowed to gain additional insights that are not directly accessible via experiments, such as an analysis of the mass density profiles, the diffusion coefficients, or the orientations of the long tails.

Published
2020
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16. Estimating the total incidence of type 1 diabetes in children and adolescents aged 0–19 years from 1990 to 2050: a global simulation-based analysis

Author

Ward, Zachary J, Yeh, Jennifer M, Reddy, Che L, Gomber, Apoorva, Ross, Carlo, Rittiphairoj, Thanitsara, Manne-Goehler, Jennifer, Abdalla, Asmahan T, Abdullah, Mohamed Ahmed, Ahmed, Abdurezak, Ankotche, Amos, Azad, Kishwar, Bahendeka, Silver, Baldé, Naby, Jain, Sunil M, Kalobu, Jean Clovis, Karekezi, Catherine, Kol, Hero, Prasannakumar, K M, Leik, Sai Kham, Mbanya, Jean Claude, Mbaye, Maïmouna Ndour, Niang, Babacar, Paturi, Vishnupriya Rao, Raghupathy, Palany, Ramaiya, Kaushik, Sethi, Bipin, Zabeen, Bedowra, and Atun, Rifat

Published
2022
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21. Association of continuous BMI with health‐related quality of life in the United States by age and sex.

Author

Ward, Zachary J., Dupuis, Roxanne, Long, Michael W., and Gortmaker, Steven L.

Subjects
WEIGHT gain, BODY weight, QUALITY of life, OBESITY, FEMALES
Abstract

Objective: The objective of this study is to estimate health‐related quality of life (HRQoL) by continuous BMI by age, sex, and demographic group in the United States. Methods: We estimated HRQoL (overall and by domain) by continuous BMI using SF‐6D (Short‐Form Six‐Dimension) data from 182,778 respondents ages 18 years and older from the repeated cross‐sectional Medical Expenditure Panel Survey (MEPS) 2008 to 2016. We adjusted for BMI self‐report bias and for potential confounding between BMI and HRQoL. Results: We found an inverse J‐shaped curve of HRQoL by BMI, with lower values for female individuals and the highest health utilities occurring at BMI of 20.4 kg/m2 (95% CI: 20.32–20.48) for female individuals and 26.5 kg/m2 (95% CI: 26.45–26.55) for male individuals. By BMI category, excess weight contributed to HRQoL loss of 0.0349 for obesity overall, rising to 0.0724 for class III obesity. By domain, pain was the largest cause of HRQoL loss for obesity (26%), followed by role limitations (22%). Conclusions: HRQoL is lower for people with excess body weight across a broad range of ages and BMI levels, especially at high levels of BMI, with pain being the largest driver of HRQoL loss. These findings highlight the importance of promoting a healthy weight for the entire population while also targeting efforts to prevent extreme weight gain over the life course. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Telehealth in Libraries: The Creation of a Novel Pre-Implementation Workbook.

Author

Ward, Zachary D., Hamann, Kasia, and DeGuzman, Pamela B.

Subjects
*MEDICAL care, *INTERNET speed, *INTERNET access, *MEDICAL personnel, *COMMUNITY organization, *PUBLIC libraries
Abstract

Telehealth services are a growing aspect of the US healthcare delivery system. Some rural patients, however, lack proper internet speed in their home to access telehealth services and need alternative telehealth access points. Public libraries can be an alternative telehealth access point due to their access to high-speed internet services; however, these programs often experience limited success due to a lack of planning with community health providers and local health organizations. This article describes a novel workbook that guides public libraries to collaborate with community stakeholders when considering the implementation of telehealth services. Development of the workbook leveraged expertise of library and public health professionals. The workbook is currently free to download and updated versions will be available as more knowledge is gained in the field. [ABSTRACT FROM AUTHOR]

Published
2024
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35. Sustainable care for children with cancer: a Lancet Oncology Commission

Author

Atun, Rifat, Bhakta, Nickhill, Denburg, Avram, Frazier, A Lindsay, Friedrich, Paola, Gupta, Sumit, Lam, Catherine G, Ward, Zachary J, Yeh, Jennifer M, Allemani, Claudia, Coleman, Michel P, Di Carlo, Veronica, Loucaides, Eva, Fitchett, Elizabeth, Girardi, Fabio, Horton, Susan E, Bray, Freddie, Steliarova-Foucher, Eva, Sullivan, Richard, Aitken, Joanne F, Banavali, Shripad, Binagwaho, Agnes, Alcasabas, Patricia, Antillon, Federico, Arora, Ramandeep S, Barr, Ronald D, Bouffet, Eric, Challinor, Julia, Fuentes-Alabi, Soad, Gross, Thomas, Hagander, Lars, Hoffman, Ruth I, Herrera, Cristian, Kutluk, Tezer, Marcus, Karen J, Moreira, Claude, Pritchard-Jones, Kathy, Ramirez, Oscar, Renner, Lorna, Robison, Leslie L, Shalkow, Jaime, Sung, Lillian, Yeoh, Allen, and Rodriguez-Galindo, Carlos

Published
2020
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43. Preventing gas hydrate plugging in deepwater wells

Author

Wylde, Jonathan, Bodnar, Scot, Mazzeo, Claudia, and Ward, Zachary

Subjects
Petroleum in submerged lands -- Management, Gas hydrates -- Prevention, Deep-sea drilling ships -- Management, Company business management, Business, Petroleum, energy and mining industries
Abstract

Low-dosage hydrate inhibitors are an alternative technology to thermodynamic inhibitors for preventing gas hydrates from restricting production from deepwater wells. Injecting the correct amount of a high-performance chemical has proven [...]

Published
2021

47. Sulfur Vacancy Related Optical Transitions in Graded Alloys of MoxW1‐xS2 Monolayers.

Author

Ghafariasl, Mahdi, Zhang, Tianyi, Ward, Zachary D., Zhou, Da, Sanchez, David, Swaminathan, Venkataraman, Terrones, Humberto, Terrones, Mauricio, and Abate, Yohannes

Subjects
SCANNING transmission electron microscopy, AB-initio calculations, ALLOYS, SPIN-orbit interactions, ELECTRON configuration
Abstract

Engineering electronic bandgaps is crucial for applications in information technology, sensing, and renewable energy. Transition metal dichalcogenides (TMDCs) offer a versatile platform for bandgap modulation through alloying, doping, and heterostructure formation. Here, the synthesis of a 2D MoxW1‐xS2 graded alloy is reported, featuring a Mo‐rich center that transitions to W‐rich edges, achieving a tunable bandgap of 1.85 to 1.95 eV when moving from the center to the edge of the flake. Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy showed the presence of sulfur monovacancy, VS, whose concentration varied across the graded MoxW1‐xS2 layer as a function of Mo content with the highest value in the Mo‐rich center region. Optical spectroscopy measurements supported by ab initio calculations reveal a doublet electronic state of VS, which is split due to the spin‐orbit interaction, with energy levels close to the conduction band or deep in the bandgap depending on whether the vacancy is surrounded by W atoms or Mo atoms. This unique electronic configuration of VS in the alloy gave rise to four spin‐allowed optical transitions between the VS levels and the valence bands. The study demonstrates the potential of defect and optical engineering in 2D monolayers for advanced device applications. [ABSTRACT FROM AUTHOR]

Published
2024
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