ALBERT

Description: Driven by the development of high-performance piezoelectric materials, actuators become an important tool for positioning objects with high accuracy down to nanometer scale, and have been used for a wide variety of equipment, such as atomic force microscopy and scanning tunneling microscopy. However, positioning at the subatomic scale is still a great challenge. Ultrathin piezoelectric materials may pave the way to positioning an object with extreme precision. Using ultrathin CdS thin films, we demonstrate vertical piezoelectricity in atomic scale (three to five space lattices). With an in situ scanning Kelvin force microscopy and single and dual ac resonance tracking piezoelectric force microscopy, the vertical piezoelectric coefficient ( d 33 ) up to 33 pm·V –1 was determined for the CdS ultrathin films. These findings shed light on the design of next-generation sensors and microelectromechanical devices.

Description: Free-carrier effects in a p -type semiconductor including the intra-valence-band and inter-valence-band optical transitions are primarily responsible for its optical characteristics in infrared. Attention has been paid to the inter-valence-band transitions for the development of internal photoemission (IPE) mid-wave infrared (MWIR) photodetectors. The hole transition from the heavy-hole (HH) band to the spin-orbit split-off (SO) band has demonstrated potential applications for 3–5  μ m detection without the need of cooling. However, the forbidden SO-HH transition at the Γ point (corresponding to a transition energy Δ 0 , which is the split-off gap between the HH and SO bands) creates a sharp drop around 3.6  μ m in the spectral response of p -type GaAs/AlGaAs detectors. Here, we report a study on the optical characteristics of p -type GaAs-based semiconductors, including compressively strained InGaAs and GaAsSb, and a dilute magnetic semiconductor, GaMnAs. A model-independent fitting algorithm was used to derive the dielectric function from experimental reflection and transmission spectra. Results show that distinct absorption dip at Δ 0 is observable in p -type InGaAs and GaAsSb, while GaMnAs displays enhanced absorption without degradation around Δ 0 . This implies the promise of using GaMnAs to develop MWIR IPE detectors. Discussions on the optical characteristics correlating with the valence-band structure and free-hole effects are presented.

Description: The host innate immune response is the first line of defense against pathogens and is orchestrated by the concerted expression of genes induced by microbial stimuli. Deregulated expression of these genes is linked to the initiation and progression of diseases associated with exacerbated inflammation. Here, we identify Topoisomerase 1 (Top1) as a positive regulator of RNA polymerase II (RNAPII) transcriptional activity at pathogen-induced genes. Depletion or chemical inhibition of Top1 suppresses the host response against Influenza and Ebola viruses as well as bacterial products. As a result, therapeutic pharmacological inhibition of Top1 protects mice from death in experimental models of lethal inflammation. Our results indicate that Top1 inhibition could be used as therapy against life threatening infections characterized by an acutely exacerbated immune response.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rialdi, Alex -- Campisi, Laura -- Zhao, Nan -- Lagda, Arvin Cesar -- Pietzsch, Colette -- Ho, Jessica Sook Yuin -- Martinez-Gil, Luis -- Fenouil, Romain -- Chen, Xiaoting -- Edwards, Megan -- Metreveli, Giorgi -- Jordan, Stefan -- Peralta, Zuleyma -- Munoz-Fontela, Cesar -- Bouvier, Nicole -- Merad, Miriam -- Jin, Jian -- Weirauch, Matthew -- Heinz, Sven -- Benner, Chris -- van Bakel, Harm -- Basler, Chris -- Garcia-Sastre, Adolfo -- Bukreyev, Alexander -- Marazzi, Ivan -- New York, N.Y. -- Science. 2016 Apr 28. pii: aad7993.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. ; Department of Pathology, Microbiology, and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA. ; Laboratory of Methyltransferases in Development and Disease, Institute of Molecular and Cell Biology, Singapore. ; Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Department of Biochemistry and Molecular Biology, Universitat de Valencia, Valencia, Spain. ; Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. ; Center for Autoimmune Genomics and Etiology (CAGE) and Divisions of Biomedical Informatics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA. ; Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. ; Department of Oncological Sciences, Tisch Cancer Institute and Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. ; Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany. ; Department of Structural and Chemical Biology, Department of Oncological Sciences, and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. ; Department of Cellular and Molecular Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA. Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA. ; Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA. ; Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. ivan.marazzi@mssm.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27127234" target="_blank"〉PubMed〈/a〉

Description: The valley degree of freedom in two-dimensional (2D) crystals recently emerged as a novel information carrier in addition to spin and charge. The intrinsic valley lifetime in 2D transition metal dichalcogenides (TMD) is expected to be markedly long due to the unique spin-valley locking behavior, where the intervalley scattering of the electron simultaneously requires a large momentum transfer to the opposite valley and a flip of the electron spin. However, the experimentally observed valley lifetime in 2D TMDs has been limited to tens of nanoseconds thus far. We report efficient generation of microsecond-long-lived valley polarization in WSe 2 /MoS 2 heterostructures by exploiting the ultrafast charge transfer processes in the heterostructure that efficiently creates resident holes in the WSe 2 layer. These valley-polarized holes exhibit near-unity valley polarization and ultralong valley lifetime: We observe a valley-polarized hole population lifetime of more than 1 μs and a valley depolarization lifetime (that is, intervalley scattering lifetime) of more than 40 μs at 10 K. The near-perfect generation of valley-polarized holes in TMD heterostructures, combined with ultralong valley lifetime, which is orders of magnitude longer than previous results, opens up new opportunities for novel valleytronics and spintronics applications.

Description: Although the concept of structural water that is bound inside hydrophobic pockets and helps to stabilize protein structures is well established, water has rarely found a similar role in supramolecular polymers. Water is often used as a solvent for supramolecular polymerization, however without taking the role of a comonomer for the supramolecular polymer structure. We report a low–molecular weight monomer whose supramolecular polymerization is triggered by the incorporation of water. The presence of water molecules as comonomers is essential to the polymerization process. The supramolecular polymeric material exhibits strong adhesion to surfaces, such as glass and paper. It can be used as a water-activated glue, which can be released at higher temperatures and reused many times without losing its performance.

Description: 〈p〉Establishing a direct correlation between interfacial water and heterogeneous ice nucleation (HIN) is essential for understanding the mechanism of ice nucleation. Here, we study the HIN efficiency on polyvinyl alcohol (PVA) surfaces with different densities of hydroxyl groups. We find that the HIN efficiency increases with the decreasing hydroxyl group density. By explicitly considering that interfacial water molecules of PVA films consist of "tightly bound water," "bound water," and "bulk-like water," we reveal that bulk-like water can be correlated directly to the HIN efficiency of surfaces. As the density of hydroxyl groups decreases, bulk-like water molecules can rearrange themselves with a reduced energy barrier into ice due to the diminishing constraint by the hydroxyl groups on the PVA surface. Our study not only provides a new strategy for experimentally controlling the HIN efficiency but also gives another perspective in understanding the mechanism of ice nucleation.〈/p〉

Description: 〈p〉Telomerase defers the onset of telomere shortening and cellular senescence by adding telomeric repeat DNA to chromosome ends, and its activation contributes to carcinogenesis. Telomerase minimally consists of the telomerase reverse transcriptase (TERT) and the telomerase RNA (TR). However, how telomerase assembles is largely unknown. Here, we demonstrate that PES1 (Pescadillo), a protein overexpressed in many cancers, forms a complex with TERT and TR through direct interaction with TERT, regulating telomerase activity, telomere length maintenance, and senescence. PES1 does not interact with the previously reported telomerase components Reptin, Pontin, p23, and Hsp90. PES1 facilitates telomerase assembly by promoting direct interaction between TERT and TR without affecting TERT and TR levels. PES1 expression correlates positively with telomerase activity and negatively with senescence in patients with breast cancer. Thus, we identify a previously unknown telomerase complex, and targeting PES1 may open a new avenue for cancer therapy.〈/p〉

Description: By using direct growth, we create a rotationally aligned MoS 2 /WSe 2 hetero-bilayer as a designer van der Waals heterostructure. With rotational alignment, the lattice mismatch leads to a periodic variation of atomic registry between individual van der Waals layers, exhibiting a Moiré pattern with a well-defined periodicity. By combining scanning tunneling microscopy/spectroscopy, transmission electron microscopy, and first-principles calculations, we investigate interlayer coupling as a function of atomic registry. We quantitatively determine the influence of interlayer coupling on the electronic structure of the hetero-bilayer at different critical points. We show that the direct gap semiconductor concept is retained in the bilayer although the valence and conduction band edges are located at different layers. We further show that the local bandgap is periodically modulated in the X - Y direction with an amplitude of ~0.15 eV, leading to the formation of a two-dimensional electronic superlattice.

Description: Based on the law of physics, known as “Seebeck effect,” a thermoelectric generator (TEG) produces electricity when the temperature differential is applied across the TEG. This article reports a precision method in characterizing TEG modules. A precision instrument is constructed to study thermoelectric conversion in terms of output power and efficiency of TEG modules. The maximum allowable TEG module size is 150 mm, and the preferred size is from 30 mm to 60 mm. During measurements, the highest hot side temperature is 500 °C and the cold side temperature can be adjusted from room temperature to 100 °C. A mechanical structure is developed to control the pressure and parallelism of the clamping force of the TEG on both its hot and cold sides. A heat flux measurement module is installed at its cold side, and the heat flux through TEGs can be measured in position. Finally, the energy conversion efficiency of TEGs is calculated from experimental data of both an output power and a heat flux.

Description: Volume recombination plays an important role towards plasma detachment for magnetically confined fusion devices. High quantum number states of the Balmer series of deuterium are used to study recombination. On EAST (Experimental Advanced Superconducting Tokamak), two visible spectroscopic measurements are applied for the upper/lower divertor with 13 channels, respectively. Both systems are coupled with Princeton Instruments ProEM EMCCD 1024B camera: one is equipped on an Acton SP2750 spectrometer, which has a high spectral resolution ∼0.0049 nm with 2400 gr/mm grating to measure the D α (H α ) spectral line and with 1200 gr/mm grating to measure deuterium molecular Fulcher band emissions and another is equipped on IsoPlane SCT320 using 600 gr/mm to measure high-n Balmer series emission lines, allowing us to study volume recombination on EAST and to obtain the related line averaged plasma parameters (T e , n e ) during EAST detached phases. This paper will present the details of the measurements and the characteristics of deuterium Balmer series line emissions during density ramp-up L-mode USN plasma on EAST.