de Haas-van Alphen spectroscopy and fractional quantization of magnetic-breakdown orbits in moir\'e graphene

Quantum oscillations originating from the quantization of the electron cyclotron orbits provide ultrasensitive diagnostics of electron bands and interactions in novel materials. We report on the first direct-space nanoscale imaging of the thermodynamic magnetization oscillations due to the de Haas-van Alphen effect in moir\'e graphene. Scanning by SQUID-on-tip in Bernal bilayer graphene crystal-axis-aligned to hBN reveals abnormally large magnetization oscillations with amplitudes reaching 500 {\mu}_B/electron in weak magnetic fields, unexpectedly low frequencies, and high sensitivity to the superlattice filling fraction. The oscillations allow us to reconstruct the complex band structure in exquisite detail, revealing narrow moir\'e bands with multiple overlapping Fermi surfaces separated by unusually small momentum gaps. We identify distinct sets of oscillations that violate the textbook Onsager Fermi surface sum rule, signaling formation of exotic broad-band particle-hole superposition states induced by coherent magnetic breakdown.Comment: 30 pages, 5 main text figures, 6 supplementary figure

Low-toxic metal halide perovskites: opportunities and future challenges

Over the past few years, lead halide perovskites have emerged as a class of dominant semiconductor materials in the photovoltaic (PV) field with an unprecedented sharp enhancement of power conversion efficiencies (PCEs) up to 22.1%, as well as in other promising optoelectronic applications due to their extraordinary and unique properties. However, the lead toxicity and long-term stability of these lead-based perovskites have raised considerable concerns for their real applications. Exploration of potentially low-toxic metal halide perovskite materials becomes one of the significant pivotal challenges in this century for PV, optoelectronic, and other unexplored applications. In this review, we summarize the recent progress on the development of low-toxic metal halide perovskites with a particular focus on their structures and properties, and discuss their potential applications in PV and optoelectronic devices. Moreover, we suggest current challenges and future research directions with the goal of stimulating further research interest and potential applications

Low-toxic metal halide perovskites: opportunities and future challenges

Over the past few years, lead halide perovskites have emerged as a class of dominant semiconductor materials in the photovoltaic (PV) field with an unprecedented sharp enhancement of power conversion efficiencies (PCEs) up to 22.1%, as well as in other promising optoelectronic applications due to their extraordinary and unique properties. However, the lead toxicity and long-term stability of these lead-based perovskites have raised considerable concerns for their real applications. Exploration of potentially low-toxic metal halide perovskite materials becomes one of the significant pivotal challenges in this century for PV, optoelectronic, and other unexplored applications. In this review, we summarize the recent progress on the development of low-toxic metal halide perovskites with a particular focus on their structures and properties, and discuss their potential applications in PV and optoelectronic devices. Moreover, we suggest current challenges and future research directions with the goal of stimulating further research interest and potential applications

Sequencing and Characterization of Divergent Marbling Levels in the Beef Cattle ( Muscle) Transcriptome

Marbling is an important trait regarding the quality of beef. Analysis of beef cattle transcriptome and its expression profile data are essential to extend the genetic information resources and would support further studies on beef cattle. RNA sequencing was performed in beef cattle using the Illumina High-Seq2000 platform. Approximately 251.58 million clean reads were generated from a high marbling (H) group and low marbling (L) group. Approximately 80.12% of the 19,994 bovine genes (protein coding) were detected in all samples, and 749 genes exhibited differential expression between the H and L groups based on fold change (>1.5-fold, p<0.05). Multiple gene ontology terms and biological pathways were found significantly enriched among the differentially expressed genes. The transcriptome data will facilitate future functional studies on marbling formation in beef cattle and may be applied to improve breeding programs for cattle and closely related mammals

New intelligent multifunctional SiO2/VO2 composite films with enhanced infrared light regulation performance, solar modulation capability, and superhydrophobicity

Highly transparent, energy-saving, and superhydrophobic nanostructured SiO2/VO2 composite films have been fabricated using a sol–gel method. These composite films are composed of an underlying infrared (IR)-regulating VO2 layer and a top protective layer that consists of SiO2 nanoparticles. Experimental results showed that the composite structure could enhance the IR light regulation performance, solar modulation capability, and hydrophobicity of the pristine VO2 layer. The transmittance of the composite films in visible region (Tlum) was higher than 60%, which was sufficient to meet the requirements of glass lighting. Compared with pristine VO2 films and tungsten-doped VO2 film, the near IR control capability of the composite films was enhanced by 13.9% and 22.1%, respectively, whereas their solar modulation capability was enhanced by 10.9% and 22.9%, respectively. The water contact angles of the SiO2/VO2 composite films were over 150°, indicating superhydrophobicity. The transparent superhydrophobic surface exhibited a high stability toward illumination as all the films retained their initial superhydrophobicity even after exposure to 365 nm light with an intensity of 160 mW.cm−2 for 10 h. In addition, the films possessed anti-oxidation and anti-acid properties. These characteristics are highly advantageous for intelligent windows or solar cell applications, given that they can provide surfaces with anti-fogging, rainproofing, and self-cleaning effects. Our technique offers a simple and low-cost solution to the development of stable and visible light transparent superhydrophobic surfaces for industrial applications

Novel Quasi-Solid-State Electrolytes based on Electrospun Poly(vinylidene fluoride) Fiber Membranes for Highly Efficient and Stable Dye-Sensitized Solar Cells

To obtain new highly efficient and stable quasi-solid dye-sensitized solar cells (QS-DSSCs) that can meet the requirements for the large-scale commercial application of solar cells, we have developed a novel quasi-solid-state electrolyte, based on an electrospun polyvinylidene fluoride (PVDF) membrane. The structure and properties of electrospun PVDF membranes were characterized by scanning electron microscopy (SEM), Brunauer&#8722;Emmett&#8722;Teller (BET), thermogravimetric (TG), and mechanical testing. The results indicate that the electrospun PVDF membrane has a three-dimensional network structure with extremely high porosity, which not only acts as a barrier to prevent electrolyte leakage but also provides a channel for the transmission of ions in the electrolyte, thereby effectively guaranteeing the high photoelectric conversion efficiency of the cells. The membrane was observed to withstand the conditions of hot-press (110 &#176;C), and exhibited good thermal stability and mechanical strength, which are critical for the long-term stability and safety of the cells. The photovoltaic characteristics and stabilities of QS-DSSCs were compared with DSSCs based on an ionic liquid electrolyte (L-DSSC). QS-DSSCs with an 80 &#956;m thick nanofiber electrolyte membrane showed a conversion efficiency of 8.63%, whereas an identical cell based on the corresponding ionic liquid electrolyte showed an efficiency of 9.30%. The stability test showed that, under indoor and outdoor conditions, after 390 h, the L-DSSCs failed. Meanwhile, the QS-DSSCs also maintained 84% and 77% of the original efficiency. The results show that, compared to the liquid electrolyte, the design of the quasi-solid electrolytes based on electrospun PVDF nanofiber membrane not only demonstrates the high conversion efficiency of DSSCs but also enhances the stability of the DSSCs, which provides the possibility for the fabrication of solar cells with higher efficiency and stability

Structure-dependent inhibition of human and rat 11β-hydroxysteroid dehydrogenase 2 activities by phthalates

Phthalates are diesters of phthalic acid and an alcohol moiety. Phthalates have been classified as endocrine disruptors and have a broad range of effects with unknown mechanisms. Some of the effects of phthalate are consistent with disruptions of normal glucocorticoid homeostasis, and in particular, with defective function of 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2). In the present study, we tested 12 phthalate diesters and four monoesters for the inhibition of human and rat kidney 11β-HSD2. We examined the modes of inhibition and looked for a relationship between the potency for inhibition and the chemical structures. Of the phthalate diesters we tested, dipropyl phthalate (DPrP) and di-n-butyl phthalate (DBP) significantly inhibited both human and rat 11β-HSD2 activities. The IC_50s were 85.59 µM for DPrP and 13.69 µM for DBP when calculated for rat 11β-HSD2. As diesters, 8 of the phthalates did not affect 11β-HSD2 enzyme activity. Compared to the diesters that were inhibitory, the 8 non-inhibitory phthalates, had either fewer carbons, that is 1 or 2 carbons in the alcohol moiety, or more carbons, 5–10, as a branched or unbranched chain in the alcohol moeity. However, phthalates could be inhibitors with six carbons in the alcohol moiety if the carbons were cyclized, as in dicyclohexyl phthalate (DCHP), which inhibited rat 11β-HSD2 with an IC_50 of 32.64 µM. Thus, whether a phthalate is an inhibitor may reflect the size and shape of the compound. Although the diesters are the compounds used in manufacturing and present as environmental contaminants, it is the monoester metabolites that are detected in human serum and urine. We showed that mono (2-ethylhexyl) phthalate (MEHP) significantly inhibited human (IC_50 = 110.8 ± 10.9) and rat (121.8 ± 8.5 µM) 11β-HSD2 activity even though its parent compound, di(2-ethylhexyl) phthalate (DEHP) did not. MEHP was a competitive inhibitor of 11β-HSD2 enzymatic activity. We conclude that phthalates of a certain size act as competitive inhibitors

Electron-beam radiation induced degradation of silicon nitride and its impact to semiconductor failure analysis by TEM

By in-situ transmission electron microscopy (TEM), we performed a detailed study on the electron-beam radiation damage to nanostructured silicon nitride thin-film process layers in a typical semiconductor NVM device. It was found that high-dose electron-beam radiation at 200 kV led to rapid degradation of silicon nitride process layers, i.e. thin-downing of nanostructured silicon nitride, inter-diffusion of O and N, the formation of bubble-like defects and segregation of N at neighbouring interfaces. Further detailed analysis revealed that radiation-induced modification in the microstructure and chemical composition of silicon nitride layers could be ascribed to the electron radiation induced knock-on damage and ionization damage. The radiation enhanced diffusion (RED) accounted for the continuous thin-down of the nitride process layer and the formation of bubble-like defects in thick nitride spacer process layers. The work well demonstrated the electron-beam sensitivity of nanostructured silicon nitride materials in the semiconductor devices, and thus may give useful information about electron-dose control during TEM failure analysis of the semiconductor devices containing nanostructured silicon nitride process layers

The overview of the impacts of electron radiation on semiconductor failure analysis by SEM, FIB and TEM

The paper briefly overviewed electron-beam radiation damage and its impacts on physical failure analysis by SEM, FIB and TEM. Based on our electron radiation study on some typical electron-beam sensitive materials, we discussed some interesting results associated with electron radiation damage to Lk/ULK, silicon nitride and CoFeB thin film materials in semiconductor and MRAM devices. The details included radiation induced microstructure changes., material diffusion and phase transformation. The underlying mechanism was also briefly discussed for electron radiation damage to different materials