Interplay of Landau Quantization and Interminivalley Scatterings in a Weakly Coupled Moiré Superlattice.

Double-layer quantum systems are promising platforms for realizing novel quantum phases. Here, we report a study of quantum oscillations (QOs) in a weakly coupled double-layer system composed of a large-angle twisted-double-bilayer graphene (TDBG). We quantify the interlayer coupling strength by measuring the interlayer capacitance from the QOs pattern at low temperatures, revealing electron-hole asymmetry. At high temperatures when SdHOs are thermally smeared, we observe resistance peaks when Landau levels (LLs) from two moiré minivalleys are aligned, regardless of carrier density; eventually, it results in a 2-fold increase of oscillating frequency in D, serving as compelling evidence of the magneto-intersub-band oscillations (MISOs) in double-layer systems. The temperature dependence of MISOs suggests that electron-electron interactions play a crucial role and the scattering times obtained from MISO thermal damping are correlated with the interlayer coupling strength. Our study reveals intriguing interplays among Landau quantization, moiré band structure, and scatterings.

Epitaxy of wafer-scale single-crystal MoS2 monolayer via buffer layer control.

Monolayer molybdenum disulfide (MoS2), an emergent two-dimensional (2D) semiconductor, holds great promise for transcending the fundamental limits of silicon electronics and continue the downscaling of field-effect transistors. To realize its full potential and high-end applications, controlled synthesis of wafer-scale monolayer MoS2 single crystals on general commercial substrates is highly desired yet challenging. Here, we demonstrate the successful epitaxial growth of 2-inch single-crystal MoS2 monolayers on industry-compatible substrates of c-plane sapphire by engineering the formation of a specific interfacial reconstructed layer through the S/MoO3 precursor ratio control. The unidirectional alignment and seamless stitching of MoS2 domains across the entire wafer are demonstrated through cross-dimensional characterizations ranging from atomic- to centimeter-scale. The epitaxial monolayer MoS2 single crystal shows good wafer-scale uniformity and state-of-the-art quality, as evidenced from the ~100% phonon circular dichroism, exciton valley polarization of ~70%, room-temperature mobility of ~140 cm2v-1s-1, and on/off ratio of ~109. Our work provides a simple strategy to produce wafer-scale single-crystal 2D semiconductors on commercial insulator substrates, paving the way towards the further extension of Moore's law and industrial applications of 2D electronic circuits.

Electron/infrared-phonon coupling in ABC trilayer graphene.

Stacking order plays a crucial role in determining the crystal symmetry and has significant impacts on electronic, optical, magnetic, and topological properties. Electron-phonon coupling, which is central to a wide range of intriguing quantum phenomena, is expected to be intricately connected with stacking order. Understanding the stacking order-dependent electron-phonon coupling is essential for understanding peculiar physical phenomena associated with electron-phonon coupling, such as superconductivity and charge density waves. In this study, we investigate the effect of stacking order on electron-infrared phonon coupling in graphene trilayers. By using gate-tunable Raman spectroscopy and excitation frequency-dependent near-field infrared nanoscopy, we show that rhombohedral ABC-stacked trilayer graphene has a significant electron-infrared phonon coupling strength. Our findings provide novel insights into the superconductivity and other fundamental physical properties of rhombohedral ABC-stacked trilayer graphene, and can enable nondestructive and high-throughput imaging of trilayer graphene stacking order using Raman scattering.

Quantum oscillations in field-induced correlated insulators of a moiré superlattice.

We report an observation of quantum oscillations (QOs) in the correlated insulators with valley anisotropy of twisted double bilayer graphene (TDBG). The anomalous QOs are best captured in the magneto resistivity oscillations of the insulators at v = -2, with a period of 1/B and an oscillation amplitude as high as 150 kΩ. The QOs can survive up to ∼10 K, and above 12 K, the insulating behaviors are dominant. The QOs of the insulator are strongly D dependent: the carrier density extracted from the 1/B periodicity decreases almost linearly with D from -0.7 to -1.1 V/nm, suggesting a reduced Fermi surface; the effective mass from Lifshitz-Kosevich analysis depends nonlinearly on D, reaching a minimal value of 0.1 me at D = ∼ -1.0 V/nm. Similar observations of QOs are also found at v = 2, as well as in other devices without graphite gate. We interpret the D sensitive QOs of the correlated insulators in the picture of band inversion. By reconstructing an inverted band model with the measured effective mass and Fermi surface, the density of state at the gap, calculated from thermal broadened Landau levels, agrees qualitatively with the observed QOs in the insulators. While more theoretical understandings are needed in the future to fully account for the anomalous QOs in this moiré system, our study suggests that TDBG is an excellent platform to discover exotic phases where correlation and topology are at play.

Giant Correlated Gap and Possible Room-Temperature Correlated States in Twisted Bilayer MoS_{2}.

Moiré superlattices have emerged as an exciting condensed-matter quantum simulator for exploring the exotic physics of strong electronic correlations. Notable progress has been witnessed, but such correlated states are achievable usually at low temperatures. Here, we report evidence of possible room-temperature correlated electronic states and layer-hybridized SU(4) model simulator in AB-stacked MoS_{2} homobilayer moiré superlattices. Correlated insulating states at moiré band filling factors v=1, 2, 3 are unambiguously established in twisted bilayer MoS_{2}. Remarkably, the correlated electronic state at v=1 shows a giant correlated gap of ∼126 meV and may persist up to a record-high critical temperature over 285 K. The realization of a possible room-temperature correlated state with a large correlated gap in twisted bilayer MoS_{2} can be understood as the cooperation effects of the stacking-specific atomic reconstruction and the resonantly enhanced interlayer hybridization, which largely amplify the moiré superlattice effects on electronic correlations. Furthermore, extreme large nonlinear Hall responses up to room temperature are uncovered near correlated electronic states, demonstrating the quantum geometry of moiré flat conduction band.

Low-Income Caregivers' Attitudes and Behaviors on Children's Diets: Emergent Themes on Cultural Influences and Perceived Value of Nutrition Information from Healthcare Providers.

INTRODUCTION: Limited access to affordable, healthy food and identifying as African-American or Hispanic-American are associated with greater risk of childhood obesity, especially for low-income individuals. PURPOSE: To report on (1) the emergent theme of the influence of culture on primary caregivers' behaviors and motivations when preparing meals for their families; and (2) primary caregivers' perceptions of the nutritional information they receive from health care providers. METHODS: Twelve focus groups with low-income, adult primary caregivers of children ages 3 to 6 years were conducted in Texas and the DC-Maryland-Virginia region and were segmented by race/ethnicity and access to grocery stores. RESULTS: Culture emerged as an important theme in influencing which foods participants cook at home. In some cases, that influence spilled over into the child's diet. In other instances, the food that participants reported making for their children varied from the food they make for themselves. Participants reported having high trust in health care providers, but acknowledged that health care providers' nutritional advice might not always be applicable. DISCUSSION AND CONCLUSIONS: Our findings highlight the importance of considering the role culture might play in influencing and informing caregivers' decisions regarding children's diets, and also better understanding caregivers' perceptions of health care providers as a source of nutrition information for their children.

Health Disparities in Calorie Knowledge and Confidence Among the U.S. Adult Population.

PURPOSE: Obesity prevalence has reached an all-time high in the US, affecting >40% of the population. This study's objective was to evaluate associations between demographics and self-reported calorie knowledge and self-perceived confidence in calorie knowledge ("calorie confidence"). The relationships between body mass index (BMI) and calorie knowledge and confidence were also explored. METHODS: We analyzed data from participants (n = 2171) in the crosssectional, nationally representative 2019 FDA Food Safety and Nutrition Survey using logistic regression to estimate adjusted odds ratios (AORs) and confidence intervals (95% CIs) for associations between BMI and calorie knowledge (correct/incorrect), calorie confidence (confident/not confident), and demographic characteristics, and the Wald chi square test to evaluate relationships between BMI and both calorie knowledge and confidence. RESULTS: Many of the same subgroups were more likely than others to report lack of calorie knowledge and lack of confidence in knowing the typical daily calorie intake needed to maintain a healthy weight [respective AORs (95% CIs): age (years), >60 vs 51-60, 1.7 (1.1-2.5), and 1.4 (1.0-2.0); sex, male vs female, 1.7 (1.3-2.3), and 1.7 (1.3-2.1); race/ethnicity, non-Hispanic Black vs non-Hispanic white, 3.4 (2.1-5.5), and 2.4 (1.6-3.8); education, ≤high school vs college grad, 1.5 (1.0- 2.3), and 1.9 (1.3-2.7)]. BMI was significantly correlated with calorie confidence (P = .047), such that those reporting less confidence were more likely overweight or obese [underweight/healthy (BMI < 25): 29%, overweight (25 ≤ BMI < 30): 34%, obese (BMI ≥ 30): 37%]. CONCLUSION: In certain demographic subgroups associations between calorie knowledge and confidence differed. Tailored education and outreach for these groups may help to address these disparities.

Precise control of the interlayer twist angle in large scale MoS2 homostructures.

Twist angle between adjacent layers of two-dimensional (2D) layered materials provides an exotic degree of freedom to enable various fascinating phenomena, which opens a research direction-twistronics. To realize the practical applications of twistronics, it is of the utmost importance to control the interlayer twist angle on large scales. In this work, we report the precise control of interlayer twist angle in centimeter-scale stacked multilayer MoS2 homostructures via the combination of wafer-scale highly-oriented monolayer MoS2 growth techniques and a water-assisted transfer method. We confirm that the twist angle can continuously change the indirect bandgap of centimeter-scale stacked multilayer MoS2 homostructures, which is indicated by the photoluminescence peak shift. Furthermore, we demonstrate that the stack structure can affect the electrical properties of MoS2 homostructures, where 30° twist angle yields higher electron mobility. Our work provides a firm basis for the development of twistronics.

Pet Ownership and Pet Type Influence Food Safety in the Home: Evidence from a National Survey.

ABSTRACT: Physical contact between humans and their pets increases the potential for zoonotic disease transmission. This study used the 2016 U.S. Food and Drug Administration (FDA) Food Safety Survey to compare the food handling behaviors of pet owners and non-pet owners, because poor food handling and hygiene habits can increase the likelihood of disease transmission from animals to humans. Results show that both pet ownership and pet type were important in predicting food safety behaviors. After controlling for sociodemographic factors included in this study (gender, age, household income, household size, and race or ethnicity), pet ownership was significantly associated with overall food safety practices and, more specifically, with better hand washing behaviors, kitchen cleaning, and ownership and use of a food thermometer, as well as a greater awareness of foodborne pathogens. Cat owners and cat-dog owners had better overall food safety practices and better hand washing behaviors compared with those of dog owners. After controlling for sociodemographic variables, there were no significant associations between pet ownership and perception of risks associated with unsafe food handling practices.

Systematic review of control groups in nutrition education intervention research.

BACKGROUND: Well-designed research trials are critical for determining the efficacy and effectiveness of nutrition education interventions. To determine whether behavioral and/or cognition changes can be attributed to an intervention, the experimental design must include a control or comparison condition against which outcomes from the experimental group can be compared. Despite the impact different types of control groups can have on study outcomes, the treatment provided to participants in the control condition has received limited attention in the literature. METHODS: A systematic review of control groups in nutrition education interventions was conducted to better understand how control conditions are described in peer-reviewed journal articles compared with experimental conditions. To be included in the systematic review, articles had to be indexed in CINAHL, PubMed, PsycINFO, WoS, and/or ERIC and report primary research findings of controlled nutrition education intervention trials conducted in the United States with free-living consumer populations and published in English between January 2005 and December 2015. Key elements extracted during data collection included treatment provided to the experimental and control groups (e.g., overall intervention content, tailoring methods, delivery mode, format, duration, setting, and session descriptions, and procedures for standardizing, fidelity of implementation, and blinding); rationale for control group type selected; sample size and attrition; and theoretical foundation. RESULTS: The search yielded 43 publications; about one-third of these had an inactive control condition, which is considered a weak study design. Nearly two-thirds of reviewed studies had an active control condition considered a stronger research design; however, many failed to report one or more key elements of the intervention, especially for the control condition. None of the experimental and control group treatments were sufficiently detailed to permit replication of the nutrition education interventions studied. CONCLUSIONS: Findings advocate for improved intervention study design and more complete reporting of nutrition education interventions.