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1.
Nano Lett ; 24(26): 8189-8197, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38904278

ABSTRACT

IV-V two-dimensional materials have emerged as key contenders for polarization-sensitive and angle-resolved devices, given their inherent anisotropic physical properties. While these materials exhibit intriguing high-pressure quasi-particle behavior and phase transition, the evolution of quasi-particles and their interactions under external pressure remain elusive. Here, employing a diamond anvil cell and spectroscopic measurements coupled with first-principles calculations, we unveil rarely observed pressure-induced phonon-phonon coupling in layered SiP flakes. This coupling manifests as an anomalous phonon hardening behavior for the A1 mode within a broad wavenumber phonon softening region. Furthermore, we demonstrate the effective tuning of exciton emissions in SiP flakes under pressure, revealing a remarkable 63% enhancement in the degree of polarization (DOP) within the pressure range of 0-3.5 GPa. These findings contribute to our understanding of high-pressure phonon evolution in SiP materials and offer a strategic approach to manipulate the anisotropic performance of in-plane anisotropic 2D materials.

2.
Nano Lett ; 2024 Jul 16.
Article in English | MEDLINE | ID: mdl-39012034

ABSTRACT

The interaction between light and moiré superlattices presents a platform for exploring unique light-matter phenomena. Tailoring these optical properties holds immense potential for advancing the utilization of moiré superlattices in photonics, optoelectronics, and valleytronics. However, the control of the optical polarization state in moiré superlattices, particularly in the presence of moiré effects, remains elusive. Here, we unveil the emergence of optical anisotropy in moiré superlattices by constructing twisted WSe2/WSe2/SiP heterostructures. We report a linear polarization degree of ∼70% for moiré excitons, attributed to the spatially nonuniform charge distribution, corroborated by first-principles calculations. Furthermore, we demonstrate the modulation of this linear polarization state via the application of a magnetic field, resulting in polarization angle rotation and a magnetic-field-dependent linear polarization degree, influenced by valley coherence and moiré potential effects. Our findings demonstrate an efficient strategy for tuning the optical polarization state of moiré superlattices using heterointerface engineering.

3.
Biophys J ; 123(6): 730-744, 2024 Mar 19.
Article in English | MEDLINE | ID: mdl-38366586

ABSTRACT

Cell migration, which is primarily characterized by directional persistence, is essential for the development of normal tissues and organs, as well as for numerous pathological processes. However, there is a lack of simple and efficient tools to analyze the systematic properties of persistence based on cellular trajectory data. Here, we present a novel approach, the entropy of angular distribution , which combines cellular turning dynamics and Shannon entropy to explore the statistical and time-varying properties of persistence that strongly correlate with cellular migration modes. Our results reveal the changes in the persistence of multiple cell lines that are tightly regulated by both intra- and extracellular cues, including Arpin protein, collagen gel/substrate, and physical constraints. Significantly, some previously unreported distinctive details of persistence have also been captured, helping to elucidate how directional persistence is distributed and evolves in different cell populations. The analysis suggests that the entropy of angular distribution-based approach provides a powerful metric for evaluating directional persistence and enables us to better understand the relationships between cellular behaviors and multiscale cues, which also provides some insights into the migration dynamics of cell populations, such as collective cell invasion.


Subject(s)
Collagen , Entropy , Cell Movement , Cell Line
4.
Br J Haematol ; 2024 Jun 26.
Article in English | MEDLINE | ID: mdl-38924031

ABSTRACT

In this study, we investigated whether matched and mismatched multidrug resistance gene (MDR1) genotypes (G2677TA, C1236T and C3435T) were associated with prognosis in patients after allogeneic haematopoietic stem cell transplantation (allo-HSCT). One hundred patients after transplantation and their donors were enrolled. Matched MDR1 G2677TA donor-recipient was associated with an increased risk of non-relapse mortality (NRM) (29.5% vs. 6.2%, p = 0.002), poor overall survival (OS) (51.7% vs. 63.8%, p = 0.024) and disease-free survival (DFS) (38.6% vs. 67%, p = 0.005). There were no differences in OS, DFS or NRM between MDR1 C1236T- and C3435T-matched and -mismatched groups. Subgroup analysis suggested that within the matched MDR1 G2677TA group, male gender, haematopoietic cell transplantation-specific comorbidity index ≥1, serum creatinine >137.2 µmol/L and post-transplantation thrombocytopenia were associated with poor survival. Our results demonstrated that patients receiving matched MDR1 G2677TA allo-HSCT experienced a poorer prognosis compared with the mismatched group. The potential mechanism may involve increased expression of P-glycoprotein, leading to decreased accumulation of antimicrobial agents and ultimately contributing to the progression of inflammation. This identification of MDR1 G2677TA genotype compatibility holds promise as a valuable molecular tool for selecting donors for allo-HSCT.

5.
Small ; 20(13): e2308945, 2024 Mar.
Article in English | MEDLINE | ID: mdl-37948432

ABSTRACT

The family of metal-free molecular perovskites, an emerging novel class of eco-friendly semiconductor, welcomes a new member with a unique 1D hexagonal perovskite structure. Lowering dimensionality at molecular level is a facile strategy for crystal structure conversion, optoelectronic property regulation, and device performance optimization. Herein, the study reports the design, synthesis, packing structure, and photophysical properties of the 1D metal-free molecular perovskite-related single crystal, rac-3APD-NH4I3(rac-3APD= racemic-3-Aminopiperidinium), that features a quantum wire structure formed by infinite chains of face-sharing NH4I6 octahedra, enabling strong quantum confinement with strongly self-trapped excited (STE) states to give efficient warm orange emission with a photoluminescence quantum yield (PLQY) as high as ≈41.6%. The study accordingly unveils its photoexcited carrier dynamics: rac-3APD-NH4I3 relaxes to STE state with a short lifetime of 10 ps but decays to ground state by emitting photons with a relatively longer lifetime of 560 ps. Additionally, strong quantum confinement effect is conducive to charge transport along the octahedral channels that enables the co-planar single-crystal X-ray detectors to achieve a sensitivity as high as 1556 µC Gyair -1 cm-2. This work demonstrates the first case of photoluminescence mechanism and photophysical dynamics of 1D metal-free perovskite-related semiconductor, as well as the promise for high-performance X-ray detector.

6.
Opt Lett ; 49(14): 3986-3989, 2024 Jul 15.
Article in English | MEDLINE | ID: mdl-39008756

ABSTRACT

Recent theoretical and experimental findings have demonstrated the minimum characteristic in the harmonic spectrum of bulk MgO crystals subjected to intense laser pulses. However, the dominant mechanism behind this minimum structure is still under debate. This study simulates the harmonic spectrum from a MgO crystal in a linearly polarized laser pulse by solving multi-band semiconductor Bloch equations. The results show that the minimum feature at 20 eV in the MgO harmonic spectra from 1700 and 800 nm laser pulses is due to band dispersion and interference between interband harmonics. Notably, the disappearance of the minimum structure at 14 eV in the harmonic spectrum from the 800 nm laser is attributed to the intensity suppression of higher energy harmonics, caused by decreased electron population at the boundary of the first Brillouin zone in the multi-band case. These findings offer insights into the spectral structure of solid-state harmonics, contributing to the all-optical reconstruction of the crystal band based on its harmonic spectrum.

7.
BMC Pregnancy Childbirth ; 24(1): 295, 2024 Apr 20.
Article in English | MEDLINE | ID: mdl-38643102

ABSTRACT

BACKGROUND: Vitamin D deficiency is common in pregnancy, however, its effects has not been fully elucidated. Here, we conducted targeted metabolomics profiling to study the relationship. METHODS: This study enrolled 111 pregnant women, including sufficient group (n = 9), inadequate group (n = 49) and deficient group (n = 53). Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS)-based targeted metabonomics were used to characterize metabolite profiles associated with vitamin D deficiency in pregnancy. RESULTS: Many metabolites decreased in the inadequate and deficient group, including lipids, amino acids and others. The lipid species included fatty acyls (FA 14:3, FA 26:0; O), glycerolipids (MG 18:2), glycerophospholipids (LPG 20:5, PE-Cer 40:1; O2, PG 29:0), sterol lipids (CE 20:5, ST 28:0; O4, ST 28:1; O4). Decreased amino acids included aromatic amino acids (tryptophan, phenylalanine, tyrosine) and branched-chain amino acids (valine, isoleucine, leucine), proline, methionine, arginine, lysine, alanine, L-kynurenine,5-hydroxy-L-tryptophan, allysine. CONCLUSIONS: This targeted metabolomics profiling indicated that vitamin D supplementation can significantly affect lipids and amino acids metabolism in pregnancy.


Subject(s)
Tandem Mass Spectrometry , Vitamin D Deficiency , Female , Humans , Pregnancy , Amino Acids , Alanine , Metabolomics , Vitamin D Deficiency/complications , Lipids
8.
Altern Ther Health Med ; 30(1): 302-306, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37820655

ABSTRACT

Background: Kawasaki disease (KD), as one of the most common vascular diseases in children, will cause the risk of coronary artery lesions (CAL) without treatment. This study is to explore the expression of procalcitonin (PCT), brain natriuretic peptide (BNP), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP) and interleukin-6 (IL-6) in children with KD and their correlation with CAL. Methods: 86 KD children in Baoding Hospital of Beijing Children's Hospital were selected as the study subjects from January 2020 to June 2021. According to whether CAL occurred, they were divided into the CAL group (n=30) and NCAL group (n=56). The clinical data of the two groups were collected from the medical record system. The levels of PCT and BNP were detected by chemiluminescence microparticle assay, the CRP level was detected by immunoturbidimetry, and the levels of TNF-α and IL-6 were detected by flow immunofluorescence method. The relationship of PCT, BNP, and inflammatory factors with CAL in KD children was explored by Pearson correlation analysis. Results: The comparative result of clinical data showed no overt difference in gender, disease types, age and blood routine indexes between the two groups, except for coronary artery diameter (P >.05). The levels of PCT, BNP, CRP, TNF-α and IL-6 in CAL group were (1.70±0.39) µg/L, (289.21±29.78) ng/L, (83.16±17.35) mg/L, (9.38±1.23) pg/mL and (59.97±0.97) ng/mL, respectively. The levels of PCT, BNP, CRP, TNF-α and IL-6 in NCAL group were (1.04±0.18) µg/L, (170.85±23.58) ng/L, (69.70±16.64) mg/L, (6.32±0.73) pg/mL and (44.16±11.97) ng/mL, respectively. The levels of each index in the CAL group were notably higher than in the NCAL group (P < .001). Pearson correlation analysis revealed that PCT, BNP, CRP, TNF-α and IL-6 were positively correlated with CAL in KD children (r=0.829, 0.865, 0.823, 0.894, 0.784, P < .001). Conclusion: The increase of PCT, BNP, and inflammatory factors has a certain warning effect on CAL in KD children. In clinical practice, health care professionals should strengthen the detection of PCT, BNP and inflammatory factors in KD children, carry out early monitoring of CAL in children with high expression of biomarkers, and formulate personalized preventive intervention based on the disease progress, so as to reduce the risk of cardiovascular disease. However, due to the limitations of research conditions and methods, the sample size of this study is small, which may affect the reliability and representativeness of the conclusion. In order to provide a new direction for the clinical prevention and treatment of the disease, future work will improve the research design, expand the sample size, and carry out more in-depth exploration on the prediction of CAL in KD children.


Subject(s)
Coronary Artery Disease , Mucocutaneous Lymph Node Syndrome , Child , Humans , Procalcitonin , Interleukin-6 , Natriuretic Peptide, Brain , Tumor Necrosis Factor-alpha , Mucocutaneous Lymph Node Syndrome/complications , Mucocutaneous Lymph Node Syndrome/pathology , Coronary Vessels/metabolism , Coronary Vessels/pathology , Reproducibility of Results , C-Reactive Protein/metabolism , Coronary Artery Disease/etiology , Coronary Artery Disease/pathology
9.
Ecotoxicol Environ Saf ; 271: 115939, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38211513

ABSTRACT

BACKGROUND: Although previous studies have shown an association between prenatal exposure to perfluorinated and polyfluoroalkyl substances (PFAS) and neurodevelopmental disorders in children, the results have been inconsistent. We summarize studies on the association between prenatal PFAS exposure and neurodevelopment in children in order to better understand the relationship. OBJECTIVE: We conducted a meta-analysis of prenatal PFAS exposure and developmental outcomes associated with intellectual, executive function and behavioral difficulty in children to explore the relationship between prenatal exposure to perfluorinated and polyfluoroalkyl substances (PFAS) and neurodevelopmental disorders in children. METHODS: We searched for articles published up to August 3, 2023, included and quantified original studies on PFAS and child Intelligence Quotient (IQ), executive function and behavioral difficulty during pregnancy, and systematically summarized articles that could not be quantified. CONCLUSION: There is evidence of sex-specific relationship between PFAS exposure and children's PIQ. We found that PFOS [ß = -1.56, 95% CI = -2.96, - 0.07; exposure = per 1 ln (ng/ml) increase], PFOA [ß = -1.87, 95% CI = -3.29, - 0.46; exposure = per 1 ln (ng/ml) increase], PFHxS [ß = -2.02, 95% CI = -3.23, - 0.81; exposure = per 1 ln (ng/ml) increase] decreased performance IQ in boys, but PFOS [ß = 1.56, 95% CI = 0.06, 3.06; exposure = per 1 ln (ng/ml) increase] increased performance IQ in girls. PFAS are associated with executive function impairments in children, but not related to behavioral difficulty in children.


Subject(s)
Alkanesulfonic Acids , Environmental Pollutants , Fluorocarbons , Prenatal Exposure Delayed Effects , Male , Female , Pregnancy , Humans , Child , Fluorocarbons/toxicity , Intelligence Tests , Environmental Pollutants/toxicity , Alkanesulfonic Acids/toxicity
10.
J Integr Neurosci ; 23(1): 15, 2024 Jan 16.
Article in English | MEDLINE | ID: mdl-38287848

ABSTRACT

The utilization of assisted reproductive technologies (ART) is on the rise, resulting in a growing population of ART-conceived offspring. The health concerns of this unique population have attracted significant attention. During ART procedures, gametes and early-stage embryos are exposed to various non-physiological conditions, such as manipulation, culture media, and cryopreservation, which may disrupt embryonic development and potentially impact the health of offspring. Notably, the potential impact of ART on neurodevelopment and its association with an increased risk of neurodevelopmental disorders (NDD) later in life remains a subject of debate. This review aims to summarize the current research advancements concerning the effects of ART on neurodevelopment, specifically focusing on the evidence of the relationship between ART, epigenetic modifications, and NDD, including autism spectrum disorder, intellectual disability, attention deficit hyperactivity disorder, and cerebral palsy. Future studies should prioritize large sample sizes, rigorous adjustment for confounding factors, and the use of interdisciplinary approaches to effectively monitor the neurodevelopmental outcomes of ART-conceived children.


Subject(s)
Autism Spectrum Disorder , Neurodevelopmental Disorders , Pregnancy , Female , Child , Humans , Autism Spectrum Disorder/etiology , Reproductive Techniques, Assisted/adverse effects , Epigenesis, Genetic , Neurodevelopmental Disorders/etiology
11.
Nano Lett ; 23(19): 8833-8841, 2023 Oct 11.
Article in English | MEDLINE | ID: mdl-37726204

ABSTRACT

Moiré superlattices induced by twisted van der Waals (vdW) heterostructures or homostructures have recently gained significant attention due to their potential to generate exotic strong-correlation electronic and phonon phenomena. However, the lack of dynamic tuning for interlayer coupling of moiré superlattices hinders a thorough understanding and development of the moiré correlation state. Here, we present a dynamic tuning method for twisted WSe2/WSe2 homobilayers using a diamond anvil cell (DAC). We demonstrate the powerful tuning of interlayer coupling and observe an enhanced response to pressure for interlayer breathing modes and the rapid descent of indirect excitons in twisted WSe2/WSe2 homobilayers. Our findings indicate that the introduction of a moiré superlattice for WSe2 bilayers gives rise to hybridized excitons, which lead to the different pressure-evolution exciton behaviors compared to natural WSe2 bilayers. Our results provide a novel understanding of moiré physics and offer an effective method to tune interlayer coupling of moiré superlattices.

12.
J Environ Manage ; 366: 121725, 2024 Jul 05.
Article in English | MEDLINE | ID: mdl-38971070

ABSTRACT

Co-digestion of kitchen waste (KW) and black water (BW) can be considered as an attractive method to efficiently achieve the clean energy from waste. To find the optimal operation parameters for the co-digestion, the effects of different temperatures (35 and 55 °C) and BW:KW ratios on the reactor performances, microbial communities and metabolic pathways were studied. The results showed that the optimum BW:KW ratio was 1:3.6 and 1:4.5 for mesophilic and thermophilic optimal reactors, with methane production of 449.04 mL/g VS and 411.90 mL/g VS, respectively. Microbial communities showed significant differences between the reactors under different temperatures. For bacteria, increasing BW:KW ratio significantly promoted Defluviitoga enrichment (1.1%-9.5%) under thermophilic condition. For Archaea, the increase in BW:KW ratio promoted the enrichment of Methanosaeta (8.6%-56.4%) in the mesophilic reactor and Methanothermobacter (62.0%-89.2%) in the thermophilic reactor. The analysis of the key enzymes showed that, acetoclastic methanogenic pathway performed as the dominant under mesophilic condition, with high abundance of Acetate-CoA ligase (EC:6.2.1.1) and Pyruvate synthase (EC:1.2.7.1). Hydrogenotrophic methanogenic pathway was the main pathway in the thermophilic reactors, with high abundance of Formylmethanofuran dehydrogenase (EC:1.2.99.5).

13.
Molecules ; 29(8)2024 Apr 19.
Article in English | MEDLINE | ID: mdl-38675680

ABSTRACT

This study presents a method for analyzing dimethomorph residues in lychee using QuEChERS extraction and HPLC-MS/MS. The validation parameters for this method, which include accuracy, precision, linearity, and recovery, indicate that it meets standard validation requirements. Following first-order kinetics, the dissipation dynamic of dimethomorph in lychee was determined to range from 6.4 to 9.2 days. Analysis of terminal residues revealed that residues in whole lychee were substantially greater than those in the pulp, indicating that dimethomorph residues are predominantly concentrated in the peel. When applied twice and thrice at two dosage levels with pre-harvest intervals (PHIs) of 5, 7, and 10 days, the terminal residues in whole lychee ranged from 0.092 to 1.99 mg/kg. The terminal residues of the pulp ranged from 0.01 to 0.18 mg/kg, with the residue ratio of whole lychee to pulp consistently exceeding one. The risk quotient (RQ) for dimethomorph, even at the recommended dosage, was less than one, indicating that the potential for damage was negligible. This study contributes to the establishment of maximum residue limits (MRLs) in China by providing essential information on the safe application of dimethomorph in lychee orchards.


Subject(s)
Litchi , Tandem Mass Spectrometry , Chromatography, High Pressure Liquid/methods , Tandem Mass Spectrometry/methods , Litchi/chemistry , Morpholines/analysis , Pesticide Residues/analysis , Food Contamination/analysis
14.
Waste Manag Res ; : 734242X241231393, 2024 Mar 18.
Article in English | MEDLINE | ID: mdl-38500349

ABSTRACT

Thermal phase separation technology is a new comprehensive treatment technology, which heats oil-based cuttings to a certain temperature to vaporize oil and water components. Based on a large oil-based drilling cuttings comprehensive utilization project, the engineering design and application effect of thermal phase separation technology were analysed. The practice shows that thermal phase separation technology can reduce the oil content of purified residue to 0.1-0.2%, the average recovery rate of base oil is 94.12% and the annual recovery of base oil is about 4800 t; the purified residue does not have corrosive, leaching toxicity and other dangerous characteristics, and can be used for making bricks or building materials. Thermal phase separation technology is a comprehensive utilization and treatment technology with excellent engineering and environmental benefits, which has a high promotion value.

15.
J Am Chem Soc ; 145(20): 11227-11235, 2023 May 24.
Article in English | MEDLINE | ID: mdl-37159928

ABSTRACT

Whether and how an electron-hole pair at the donor-acceptor interface separates from their mutual Coulombic interaction has been a long-standing question for both fundamental interests and optoelectronic applications. This question is particularly interesting but yet to be unraveled in the emerging mixed-dimensional organic/2D semiconductor excitonic heterostructures where the Coulomb interaction is poorly screened. Here, by tracking the characteristic electroabsorption (Stark effect) signal from separated charges using transient absorption spectroscopy, we directly follow the electron-hole pair separation process in a model organic/2D heterostructure, vanadium oxide phthalocyanine/monolayer MoS2. After sub-100 fs photoinduced interfacial electron transfer, we observe a barrier-less long-range electron-hole pair separation to free carriers within 1 ps by hot charge transfer exciton dissociation. Further experiment reveals the key role of the charge delocalization in organic layers sustained by the local crystallinity, while the inherent in-plane delocalization of the 2D semiconductor has a negligible contribution to charge pair separation. This study reconciles the seemingly contradicting charge transfer exciton emission and dissociation process and is important to the future development of efficient organic/2D semiconductor optoelectronic devices.

16.
Small ; 19(26): e2207988, 2023 Jun.
Article in English | MEDLINE | ID: mdl-36938893

ABSTRACT

The exploration of moiré superlatticesholds promising potential to uncover novel quantum phenomena emerging from the interplay of atomic structure and electronic correlation . However, the impact of the moiré potential modulation on the number of twisted layers has yet to be experimentally explored. Here, this work synthesizes a twisted WSe2 homotrilayer using a dry-transfer method and investigates the enhancement of the moiré potential with increasing number of twisted layers. The results of the study reveal the presence of multiple exciton resonances with positive or negative circularly polarized emission in the WSe2 homostructure with small twist angles, which are attributed to the excitonic ground and excited states confined to the moiré potential. The distinct g-factor observed in the magneto-optical spectroscopy is also shown to be a result of the confinement of the exciton in the moiré potential. The moiré potential depths of the twisted bilayer and trilayer homostructures are found to be 111 and 212 meV, respectively, an increase of 91% from the bilayer structure. These findings demonstrate that the depth of the moiré potential can be manipulated by adjusting the number of stacked layers, providing a promising avenue for exploration into highly correlated quantum phenomena.

17.
J Exp Bot ; 74(6): 1911-1925, 2023 03 28.
Article in English | MEDLINE | ID: mdl-36638269

ABSTRACT

The sporopollenin polymer is a major component of the pollen exine. Fatty acid derivatives synthesized in the tapetum are among the precursors of sporopollenin. Progress has been made to understand sporopollenin metabolism in rice; however, the underlying molecular mechanisms remain elusive. We found that OsTKPR2 and OsTKPR1 share a similar expression pattern, and their coding proteins have a similar subcellular localization and enzyme activities towards reduced tetraketide α-pyrone and hydroxylated tetraketide α-pyrone. Unexpectedly, OsTKPR1pro:OsTKPR2-eGFP could not rescue the phenotype of ostkpr1-4. Three independent ostkpr2 mutant lines generated by CRISPR/Cas9 displayed reduced male fertility to various extents which were correlated with the severity of gene disruptions. Notably, the anther cuticle, Ubisch bodies, and pollen development were affected in the ostkpr2-1 mutant, where a thinner pollen exine was noticed. OsTKPR1 and OsTKPR2 were integrated into a metabolon including OsACOS12 and OsPKS2, which resulted in a significant increased enzymatic efficiency when both OsTKPR1 and OsTKPR2 were present, indicating the mutual dependence of OsTKPR2 and OsTKPR1 for their full biochemical activities. Thus, our results demonstrated that OsTKPR2 is required for anther and pollen development where an OsTKPR2-containing metabolon is functional during rice sporopollenin synthesis. Furthermore, the cooperation and possible functional divergence between OsTKPR2 and OsTKPR1 is also discussed.


Subject(s)
Oryza , Plant Proteins , Plant Proteins/genetics , Plant Proteins/metabolism , Oryza/metabolism , Pyrones/metabolism , Gene Expression Regulation, Plant
18.
Opt Lett ; 48(22): 5867-5870, 2023 Nov 15.
Article in English | MEDLINE | ID: mdl-37966739

ABSTRACT

Two-dimensional (2D) semiconductors featuring low-symmetry crystal structures hold an immense potential for the design of advanced optoelectronic devices, leveraging their inherent anisotropic attributes. While the synthesis techniques for transition metal dichalcogenides (TMDs) have matured, a promising avenue emerges: the induction of anisotropy within symmetric TMDs through interlayer van der Waals coupling engineering. Here, we unveil the creation of heterostructures (HSs) by stacking highly symmetric MoSe2 with low-symmetry ReS2, introducing artificial anisotropy into monolayer MoSe2. Through a meticulous analysis of angle-dependent photoluminescence (PL) spectra, we discern a remarkable anisotropic intensity ratio of approximately 1.34. Bolstering this observation, the angle-resolved Raman spectra provide unequivocal validation of the anisotropic optical properties inherent to MoSe2. This intriguing behavior can be attributed to the in-plane polarization of MoSe2, incited by the deliberate disruption of lattice symmetry within the monolayer MoSe2 structure. Collectively, our findings furnish a conceptual blueprint for engineering both isotropic and anisotropic HSs, thereby unlocking an expansive spectrum of applications in the realm of high-performance optoelectronic devices.

19.
Opt Lett ; 48(9): 2393-2396, 2023 May 01.
Article in English | MEDLINE | ID: mdl-37126281

ABSTRACT

Monolayer transition metal dichalcogenides (TMDs) have a crystalline structure with broken spatial inversion symmetry, making them promising candidates for valleytronic applications. However, the degree of valley polarization is usually not high due to the presence of intervalley scattering. Here, we use the nanoindentation technique to fabricate strained structures of WSe2 on Au arrays, thus demonstrating the generation and detection of strained localized excitons in monolayer WSe2. Enhanced emission of strain-localized excitons was observed as two sharp photoluminescence (PL) peaks measured using low-temperature PL spectroscopy. We attribute these emerging sharp peaks to excitons trapped in potential wells formed by local strains. Furthermore, the valley polarization of monolayer WSe2 is modulated by a magnetic field, and the valley polarization of strained localized excitons is increased, with a high value of up to approximately 79.6%. Our results show that tunable valley polarization and localized excitons can be realized in WSe2 monolayers, which may be useful for valleytronic applications.

20.
FASEB J ; 36(8): e22460, 2022 08.
Article in English | MEDLINE | ID: mdl-35881062

ABSTRACT

Pancreatic islet cell development is regulated by transcription factors (TFs) that mediate embryonic progenitor differentiation toward mature endocrine cells. Prior studies from our lab and others showed that the islet-enriched TF, Islet-1 (Isl1), interacts with the broadly-expressed transcriptional co-regulator, Ldb1, to regulate islet cell maturation and postnhyperatal function (by embryonic day (E)18.5). However, Ldb1 is expressed in the developing pancreas prior to Isl1 expression, notably in multipotent progenitor cells (MPCs) marked by Pdx1 and endocrine progenitors (EPs) expressing Neurogenin-3 (Ngn3). MPCs give rise to the endocrine and exocrine pancreas, while Ngn3+ EPs specify pancreatic islet endocrine cells. We hypothesized that Ldb1 is required for progenitor identity in MPC and EP populations during development to impact islet appearance and function. To test this, we generated a whole-pancreas Ldb1 knockout, termed Ldb1ΔPanc , and observed severe developmental and postnatal pancreas defects including disorganized progenitor pools, a significant reduction of Ngn3-expressing EPs, Pdx1HI ß-cells, and early hormone+ cells. Ldb1ΔPanc neonates presented with severe hyperglycemia, hypoinsulinemia, and drastically reduced hormone expression in islets, yet no change in total pancreas mass. This supports the endocrine-specific actions of Ldb1. Considering this, we also developed an endocrine-enriched model of Ldb1 loss, termed Ldb1ΔEndo . We observed similar dysglycemia in this model, as well as a loss of islet identity markers. Through in vitro and in vivo chromatin immunoprecipitation experiments, we found that Ldb1 occupies key Pdx1 and Ngn3 promoter domains. Our findings provide insight into novel regulation of endocrine cell differentiation that may be vital toward improving cell-based diabetes therapies.


Subject(s)
Homeodomain Proteins , Islets of Langerhans , Basic Helix-Loop-Helix Transcription Factors/genetics , Basic Helix-Loop-Helix Transcription Factors/metabolism , Cell Differentiation , DNA-Binding Proteins/metabolism , Gene Expression Regulation , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolism , Hormones/metabolism , Humans , Infant, Newborn , Islets of Langerhans/metabolism , LIM Domain Proteins/genetics , Pancreas , Transcription Factors/genetics , Transcription Factors/metabolism
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