Phase-Selective Synthesis of Rhombohedral WS2 Multilayers by Confined-Space Hybrid Metal-Organic Chemical Vapor Deposition.

Rhombohedral polytype transition metal dichalcogenide (TMDC) multilayers exhibit non-centrosymmetric interlayer stacking, which yields intriguing properties such as ferroelectricity, a large second-order susceptibility coefficient χ(2), giant valley coherence, and a bulk photovoltaic effect. These properties have spurred significant interest in developing phase-selective growth methods for multilayer rhombohedral TMDC films. Here, we report a confined-space, hybrid metal-organic chemical vapor deposition method that preferentially grows 3R-WS2 multilayer films with thickness up to 130 nm. We confirm the 3R stacking structure via polarization-resolved second-harmonic generation characterization and the 3-fold symmetry revealed by anisotropic H2O2 etching. The multilayer 3R WS2 shows a dendritic morphology, which is indicative of diffusion-limited growth. Multilayer regions with large, stepped terraces enable layer-resolved evaluation of the optical properties of 3R-WS2 via Raman, photoluminescence, and differential reflectance spectroscopy. These measurements confirm the interfacial quality and suggest ferroelectric modification of the exciton energies.

Chemically Tailored Growth of 2D Semiconductors via Hybrid Metal-Organic Chemical Vapor Deposition.

Two-dimensional (2D) semiconducting transition-metal dichalcogenides (TMDCs) are an exciting platform for excitonic physics and next-generation electronics, creating a strong demand to understand their growth, doping, and heterostructures. Despite significant progress in solid-source (SS-) and metal-organic chemical vapor deposition (MOCVD), further optimization is necessary to grow highly crystalline 2D TMDCs with controlled doping. Here, we report a hybrid MOCVD growth method that combines liquid-phase metal precursor deposition and vapor-phase organo-chalcogen delivery to leverage the advantages of both MOCVD and SS-CVD. Using our hybrid approach, we demonstrate WS2 growth with tunable morphologies─from separated single-crystal domains to continuous monolayer films─on a variety of substrates, including sapphire, SiO2, and Au. These WS2 films exhibit narrow neutral exciton photoluminescence line widths down to 27-28 meV and room-temperature mobility up to 34-36 cm2 V-1 s-1. Through simple modifications to the liquid precursor composition, we demonstrate the growth of V-doped WS2, MoxW1-xS2 alloys, and in-plane WS2-MoS2 heterostructures. This work presents an efficient approach for addressing a variety of TMDC synthesis needs on a laboratory scale.

Deterministic fabrication of graphene hexagonal boron nitride moiré superlattices.

The electronic properties of moiré heterostructures depend sensitively on the relative orientation between layers of the stack. For example, near-magic-angle twisted bilayer graphene (TBG) commonly shows superconductivity, yet a TBG sample with one of the graphene layers rotationally aligned to a hexagonal Boron Nitride (hBN) cladding layer provided experimental observation of orbital ferromagnetism. To create samples with aligned graphene/hBN, researchers often align edges of exfoliated flakes that appear straight in optical micrographs. However, graphene or hBN can cleave along either zig-zag or armchair lattice directions, introducing a [Formula: see text] ambiguity in the relative orientation of two flakes. By characterizing the crystal lattice orientation of exfoliated flakes prior to stacking using Raman and second-harmonic generation for graphene and hBN, respectively, we unambiguously align monolayer graphene to hBN at a near-[Formula: see text], not [Formula: see text], relative twist angle. We confirm this alignment by torsional force microscopy of the graphene/hBN moiré on an open-face stack, and then by cryogenic transport measurements, after full encapsulation with a second, nonaligned hBN layer. This work demonstrates a key step toward systematically exploring the effects of the relative twist angle between dissimilar materials within moiré heterostructures.

Teledermatology Use in the Elderly: An Analysis of Teledermatology Utilization Patterns Across Age Groups.

Introduction: Telehealth is an emerging tool used to improve access to care for patients. However, there is a lack of literature comparing the use of telehealth between patients of different age groups in dermatology. Our study aims to determine whether differences exist in teledermatology usage between elderly and younger dermatology patients. Methods: We conducted a cross-sectional study using the 2020-2021 Medical Expenditure Panel Survey. Our study population included a weighted total of 150,290,604 patients: Of these, 16.35% were young adults (18-44 years old), 26.32% were midlife adults (45-64 years old), and 57.33% were elderly (65+ years old). Results: Our results showed that elderly patients had significantly lower rates of teledermatology use than young adults (odds ratio [OR] = 0.184, (confidence interval [CI]: 0.081-0.421)), p < 0.000) and midlife adults (OR = 0.193, [CI: 0.091-0.406], p < 0.000). Midlife adults had similar rates of telehealth use when compared with young adults (OR = 1.044, [CI: 0.508-2.145], p = 0.907). Our results were adjusted for sex, race, ethnicity, insurance type, education level, income, travel time, and medical comorbidities. Discussion: We found that elderly patients seeking dermatology care are less likely to use telehealth than younger dermatology patients. Our results demonstrate that barriers to telehealth use for the elderly may be more prohibitive than expected. Understanding these differences in teledermatology use is essential for improving teledermatology delivery across all age groups.

Coronary Microvascular Dysfunction is Associated with Augmented Lysosomal Signaling in Hypercholesterolemic Mice.

Accumulating evidence indicates that coronary microvascular dysfunction (CMD) caused by hypercholesterolemia can lead to myocardial ischemia, with or without obstructive atherosclerotic coronary artery disease (CAD). However, the molecular pathways associated with compromised coronary microvascular function prior to the development of myocardial ischemic injury remain poorly defined. In this study, we investigated the effects of hypercholesterolemia on the function and integrity of the coronary microcirculation in mice and the underlying mechanisms. Mice were fed with a hypercholesterolemic Paigen's diet (PD) for 8 weeks. Echocardiography data showed that PD caused CMD, characterized by significant reductions in coronary blood flow and coronary flow reserve (CFR), but did not affect cardiac remodeling or dysfunction. Immunofluorescence studies revealed that PD-induced CMD was associated with activation of coronary arterioles inflammation and increased myocardial inflammatory cell infiltration. These pathological changes occurred in parallel with the upregulation of lysosomal signaling pathways in endothelial cells (ECs). Treating hypercholesterolemic mice with the cholesterol-lowering drug ezetimibe significantly ameliorated PD-induced adverse effects, including hypercholesterolemia, steatohepatitis, reduced CFR, coronary EC inflammation, and myocardial inflammatory cell infiltration. In cultured mouse cardiac endothelial cells (MCECs), 7-ketocholesterol (7K) increased mitochondrial reactive oxygen species (ROS) and inflammatory responses. Meanwhile, 7K induced the activation of TFEB and lysosomal signaling in MCECs, whereas the lysosome inhibitor bafilomycin A1 blocked 7K-induced TFEB activation and exacerbated 7K-induced inflammation and cell death. Interestingly, ezetimibe synergistically enhanced 7K-induced TFEB activation and attenuated 7K-induced mitochondrial ROS and inflammatory responses in MCECs. These results suggest that CMD can develop and precede detectable cardiac functional or structural changes in the setting of hypercholesterolemia, and that upregulation of TFEB-mediated lysosomal signaling in ECs plays a protective role against CMD.

Influence of Anatomic Locations of T1b Melanomas and Patient Age on Outcomes.

BACKGROUND: There are no guidelines on when to more strongly recommend sentinel lymph node biopsy (SLNB) for T1b melanomas. OBJECTIVE: To examine whether anatomic locations of T1b melanomas and patient age influence metastases. METHODS: We conducted a retrospective study using data from two hospitals in Los Angeles County from January 2010 through January 2020. RESULTS: Out of 620 patients with primary melanomas, 566 melanomas were staged based on the American Joint Committee on Cancer 8th edition melanoma staging. Forty-one were T1b, of which 13 were located on the face/ear/scalp and 28 were located elsewhere. T1b melanomas located on the face/ear/scalp had an increased risk of lymph node or distant metastasis compared with other anatomic sites (31% vs 3.6%, P=0.028). For all melanomas, the risk of lymph node or distant metastasis decreased with age of 64 years or greater (P<0.001 and P=0.034). For T1b melanomas, the risk of distant metastasis increased with increasing age (P=0.047). LIMITATIONS: Data were from a single county.  Conclusion: T1b melanomas of the face/ear/scalp demonstrated a higher risk of lymph node or distant metastasis and may help guide the recommendation of SLNB, imaging, and surveillance. Younger patients may be more strongly considered for SLNB and older patients with T1b melanomas may warrant imaging.  J Drugs Dermatol. 2024;23(5):306-310. doi:10.36849/JDD.7667.

Tunable Phonon Polariton Hybridization in a Van der Waals Hetero-Bicrystal.

Phonon polaritons, the hybrid quasiparticles resulting from the coupling of photons and lattice vibrations, have gained significant attention in the field of layered van der Waals heterostructures. Particular interest has been paid to hetero-bicrystals composed of molybdenum oxide (MoO3) and hexagonal boron nitride (hBN), which feature polariton dispersion tailorable via avoided polariton mode crossings. In this work, the polariton eigenmodes in MoO3-hBN hetero-bicrystals self-assembled on ultrasmooth gold are systematically studied using synchrotron infrared nanospectroscopy. It is experimentally demonstrated that the spectral gap in bicrystal dispersion and corresponding regimes of negative refraction can be tuned by material layer thickness, and these results are quantitatively matched with a simple analytic model. Polaritonic cavity modes and polariton propagation along "forbidden" directions are also investigated in microscale bicrystals, which arise from the finite in-plane dimension of the synthesized MoO3 micro-ribbons. The findings shed light on the unique dispersion properties of polaritons in van der Waals heterostructures and pave the way for applications leveraging deeply sub-wavelength mid-infrared light-matter interactions.

Is Blepharoplasty Cost-effective? Utility Analysis of Dermatochalasis and Cost-effectiveness Analysis of Upper Eyelid Blepharoplasty.

PURPOSE: This cross-sectional prospective study measured utility values of upper eyelid dermatochalasis to quantify its impact on quality of life and assess cost-effectiveness of upper blepharoplasty. METHODS: Utility of dermatochalasis was assessed using the standard reference gamble and time trade-off methods, with dual anchor points of perfect eye function and perfect health. The utility value obtained was used to create a Markov model and run a cost-effectiveness analysis of blepharoplasty as a treatment for dermatochalasis while utilizing the societal perspective. RESULTS: One hundred three patients with dermatochalasis recruited from an urban outpatient ophthalmology clinic completed the utility survey. The authors determined utility values for dermatochalasis ranging from 0.74 to 0.92 depending on the measurement method (standard reference gamble/time trade-off) and anchor points. The cost-effectiveness analysis yielded an incremental cost-effectiveness ratio of $3,146 per quality-adjusted life year, well under the conventional willingness-to-pay threshold of $50,000 per quality-adjusted life year. Probabilistic sensitivity analysis with Monte Carlo simulation demonstrated that blepharoplasty would be cost-effective in 88.1% of cases at this willingness-to-pay threshold. CONCLUSIONS: Dermatochalasis has an impact on quality of life that is significantly associated with level of perceived functional impairment. Rising health care costs have underscored the importance of providing value-based treatment to patients, and the results of this study suggest that blepharoplasty is a cost-effective treatment option for symptomatic bilateral upper eyelid dermatochalasis.

Quantum control of exciton wave functions in 2D semiconductors.

Excitons-bound electron-hole pairs-play a central role in light-matter interaction phenomena and are crucial for wide-ranging applications from light harvesting and generation to quantum information processing. A long-standing challenge in solid-state optics has been to achieve precise and scalable control over excitonic motion. We present a technique using nanostructured gate electrodes to create tailored potential landscapes for excitons in 2D semiconductors, enabling in situ wave function shaping at the nanoscale. Our approach forms electrostatic traps for excitons in various geometries, such as quantum dots, rings, and arrays thereof. We show independent spectral tuning of spatially separated quantum dots, achieving degeneracy despite material disorder. Owing to the strong light-matter coupling of excitons in 2D semiconductors, we observe unambiguous signatures of confined exciton wave functions in optical reflection and photoluminescence measurements. This work unlocks possibilities for engineering exciton dynamics and interactions at the nanometer scale, with implications for optoelectronic devices, topological photonics, and quantum nonlinear optics.

Axial length and pharmacologic pupillary dilation in highly myopic patients.

PURPOSE: To determine how high myopia impacts pharmacological pupillary dilation, and to evaluate the relationship between the extent of pharmacologic pupillary dilation and axial length. METHODS: Patients were grouped into high myopes, defined as one or both eyes having a refractive error greater than - 6 diopters, and controls (between - 2 and + 2 diopters). Dilation was achieved with 1 drop each of tropicamide 1% and phenylephrine 2.5%. Pupil size was measured at full and dim light prior to dilation, then 15 and 30 min after dilation. Biometry was measured for each patient. Statistical analyses were performed using the Mann-Whitney-Wilcoxon tests, two-sample Welch's t-tests, and linear mixed effect models and generalized estimating equations models accounting for inter-eye correlation. RESULTS: Forty patients (20 high myopes and 20 controls, 80 eyes total) participated in the study. High myopes had larger pupils at baseline and achieved significantly greater pupillary size (7.08 mm, 95% CI: 6.97 to 7.19 mm) than controls (6.23 mm, 95% CI: 5.94 to 6.52 mm) after 30 min of dilation (P < .0005). Fully dilated pupil size at 30 min was significantly correlated with both refractive error (r = - 0.57, P < .0005) and axial length (r = 0.47, P < .0005). Generalized estimating equations and linear mixed effect models identified other predictive variables of pupil size after dilation including age and white-to-white diameter. CONCLUSIONS: Highly myopic patients dilate to a larger pupillary size compared to other patients. Predicting dilation based on extent of myopia could facilitate intraocular surgery planning and reduce clinic wait times for myopic patients.

Cost-Effectiveness Analysis of Light Adjustable Lens Compared to Monofocal Intraocular Lens in Cataract Surgery.

PURPOSE: To analyze the cost-effectiveness of the Light Adjustable Lens (LAL; RxSight) in comparison to a monofocal intraocular lens (IOL) for individuals undergoing cataract surgery in both eyes. METHODS: A cost-effectiveness analysis was performed using a Markov model that simulated the patient outcomes and costs associated with undergoing cataract surgery with the LAL or monofocal IOL. Cost-effectiveness was determined using the incremental cost-effectiveness ratio (ICER), a measure that quantifies the incremental cost in dollars per quality-adjusted life year (QALY) gained. Treatments with the ICER below the willingness-to-pay threshold (WTP) of $50,000/QALY were considered cost-effective. The model was also evaluated for the impact of uncertainties in parameters using one-way sensitivity and probabilistic sensitivity analyses. RESULTS: The cost-effectiveness analysis showed that the LAL is cost-effective compared to monofocal IOLs in patients undergoing cataract surgery, with ICERs of $9,792/QALY (health care perspective) and $10,072/QALY (societal perspective) both significantly below the WTP. The model was most sensitive to patient age, market cost of the LAL, and proportion of patients with residual astigmatism following cataract surgery. The probabilistic sensitivity analysis showed that cataract surgeries in patients starting at age 65 years were cost-effective in 94% of the simulations at a WTP of $50,000/QALY. CONCLUSIONS: From both health care and societal perspectives, the study shows cataract surgeries performed with the LAL are cost-effective when compared to those performed with a monofocal IOL. More studies are needed to compare the LAL to other premium lenses that also provide patients with excellent visual outcomes at a higher cost. [J Refract Surg. 2023;39(11):777-782.].

Moiré-Assisted Strain Transfer in Vertical van der Waals Heterostructures.

Strain provides a powerful method to study 2D monolayers and to tune their properties. The same approach also has great potential for van-der-Waals (vdW) heterostructures. However, we need to understand how strain can be applied to vertically stacked vdW structures, for which strain transfer from one layer to the next remains little explored. In our experiment, we fabricated vertical heterostructures consisting of transition metal dichalcogenides (TMDCs) monolayers that were deposited on a flexible substrate. These TMDC heterostructures allowed us to read out separately the strain in each monolayer by photoluminescence measurements. We find that, in TMDC heterostructures with large twist angles (>5°), strain transfer is limited. However, for aligned heterostructures with small twist angles (≤5°), near unity strain transfer efficiency is observed. We correlate this finding with the moiré domains formed in the aligned heterostructures by reconstruction.

Observation of quadrupolar and dipolar excitons in a semiconductor heterotrilayer.

Van der Waals (vdW) materials have opened up many avenues for discovery through layer assembly, as epitomized by interlayer dipolar excitons that exhibit electrically tunable luminescence, lasing and exciton condensation. Extending interlayer excitons to more vdW layers, however, raises fundamental questions concerning coherence within excitons and coupling between moiré superlattices at multiple interfaces. Here, by assembling angle-aligned WSe2/WS2/WSe2 heterotrilayers, we demonstrate the emergence of quadrupolar excitons. We confirm the exciton's quadrupolar nature by the decrease in its energy of 12 meV from coherent hole tunnelling between the two outer layers, its tunable static dipole moment under an external electric field and the reduced exciton-exciton interactions. At high exciton density, we also see signatures of a phase of oppositely aligned dipolar excitons, consistent with a staggered dipolar phase predicted to be driven by attractive dipolar interactions. Our demonstration paves the way for discovering emergent exciton orderings for three vdW layers and beyond.

Cost-effectiveness analysis of endoscopic dacryocystorhinostomy using Markov modelling.

OBJECTIVE: To determine the cost-effectiveness of endoscopic dacryocystorhinostomy (DCR). METHODS: We constructed a Markov model in which patients with nasolacrimal duct obstruction received endoscopic DCR or no surgery. Incremental cost-effectiveness ratios, 1-way sensitivity analyses, and probabilistic sensitivity analyses were used to evaluate for model sensitivity to multiple model inputs. RESULTS: Endoscopic DCR was found to be cost-effective with an incremental cost-effectiveness ratio of US$2162 per quality-adjusted life-year. The model was most sensitive to the health utility deduction from epiphora. Probabilistic sensitivity analysis found endoscopic DCR to be cost-effective over no surgery 93.7% of the time. CONCLUSIONS: Endoscopic DCR is a cost-effective treatment for patients with epiphora. The model is very sensitive to the negative effect epiphora has on quality of life. With the advancement of health care technology and surgical techniques, the success rates of endoscopic DCR continue to improve and to be an even more efficacious and economical treatment for nasolacrimal duct obstruction.