Weyl semimetals host chiral fermions with distinct chiralities and spin textures. Optical excitations involving those chiral fermions can induce exotic carrier responses, and in turn lead to novel ...optical phenomena. Here, we discover strong coherent terahertz emission from Weyl semimetal TaAs, which is demonstrated as a unique broadband source of the chiral terahertz wave. The polarization control of the THz emission is achieved by tuning photoexcitation of ultrafast photocurrents via the photogalvanic effect. In the near-infrared regime, the photon-energy dependent nonthermal current due to the predominant circular photogalvanic effect can be attributed to the radical change of the band velocities when the chiral Weyl fermions are excited during selective optical transitions between the tilted anisotropic Weyl cones and the massive bulk bands. Our findings provide a design concept for creating chiral photon sources using quantum materials and open up new opportunities for developing ultrafast opto-electronics using Weyl physics.
In cancer, epigenetic proteins are intensely studied targets for therapeutic drug discovery, showing great promise. These proteins include the chromatin-modifying enzymes that "write" and "erase" ...histone posttranslational modifications (PTM), and those that "read" these marks through binding modules. In an effort to find a compound that could disrupt the protein-protein interactions between a PTM and reader, JQ1 has proven to be a first-in-class, drug-like inhibitor of the "bromodomain and extraterminal domain" epigenetic readers (BETs), which recognize histone lysine acetylation marks. JQ1 has facilitated the mechanistic study and therapeutic application in cancer of this kind of epigenetic inhibition. By using this chemical probe, we have discovered that the bromodomain inhibitors (BETi) have compelling activity in preclinical models of multiple myeloma and acute myeloid leukemia. In particular, BETi down-regulates the MYC, IL-7R, and E2F transcriptional programs. We are continuously integrating the transcriptional consequences of BETi with changes in the epigenomic landscapes of cancer cells to elucidate the mechanisms underlying response to BETi using chemical and genetic perturbations.
The biosorption of Cu(II) onto chestnut shell, a residue of the food processing industry, in a batch adsorber has been studied. Equilibrium isotherms, kinetic data, and thermodynamic parameters have ...been evaluated. Equilibrium data agreed well with Langmuir isotherm and Redlich–Peterson isotherm models. The adsorption capacity of chestnut shell for Cu(II) was determined with the Langmuir model and was found to be 12.56
mg
g
−1 at 293
K. The kinetic data were found to follow the pseudo-second-order model. Intra-particle diffusion is not the sole rate-controlling factor. Gibbs free energy was spontaneous for all interactions, and the adsorption process exhibited exothermic enthalpy values. Chestnut shell was shown to be a promising biosorbent for Cu(II) removal from aqueous solutions.
The formation of a trivalent conversion coating on aluminium has been investigated using analytical electron microscopy, atomic force microscopy, ion beam analysis, glow discharge optical emission ...spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The coating is shown to comprise a chromium- and zirconium-rich outer layer and an aluminium-rich inner layer. Zirconium and chromium are present in chemical states consistent with ZrO2, ZrF4, Cr(OH)3, Cr2(SO4)3, CrF3 and CrO3 or CrO42−. However, negligible amounts of Cr(VI) species occurred in coatings formed in de-aerated solution. Electrochemical impedance spectroscopy revealed that the inner layer provides the main corrosion protection during short-term tests in 0.1M sodium sulphate solution at room temperature.
•Trivalent chromium conversion coatings are formed on aluminium.•Coatings are examined by TEM, revealing kinetics of growth and bi-layer morphology.•RBS, NRA and XPS are used to determine elemental concentrations and chemical states.•Raman spectroscopy indicates Cr(VI) is formed during coating growth.•Inner coating layer provides the main corrosion protection.
The primary aim of this study was to evaluate the antitumor efficacy of the bromodomain inhibitor JQ1 in pancreatic ductal adenocarcinoma (PDAC) patient-derived xenograft (tumorgraft) models. A ...secondary aim of the study was to evaluate whether JQ1 decreases expression of the oncogene c-Myc in PDAC tumors, as has been reported for other tumor types. We used five PDAC tumorgraft models that retain specific characteristics of tumors of origin to evaluate the antitumor efficacy of JQ1. Tumor-bearing mice were treated with JQ1 (50 mg/kg daily for 21 or 28 days). Expression analyses were performed with tumors harvested from host mice after treatment with JQ1 or vehicle control. An nCounter PanCancer Pathways Panel (NanoString Technologies) of 230 cancer-related genes was used to identify gene products affected by JQ1. Quantitative RT-PCR, immunohistochemistry and immunoblots were carried out to confirm that changes in RNA expression reflected changes in protein expression. JQ1 inhibited the growth of all five tumorgraft models (P<0.05), each of which harbors a KRAS mutation; but induced no consistent change in expression of c-Myc protein. Expression profiling identified CDC25B, a regulator of cell cycle progression, as one of the three RNA species (TIMP3, LMO2 and CDC25B) downregulated by JQ1 (P<0.05). Inhibition of tumor progression was more closely related to decreased expression of nuclear CDC25B than to changes in c-Myc expression. JQ1 and other agents that inhibit the function of proteins with bromodomains merit further investigation for treating PDAC tumors. Work is ongoing in our laboratory to identify effective drug combinations that include JQ1.
The histone demethylase JMJD1A, which controls gene expression by epigenetic regulation of H3K9 methylation marks, functions in diverse activities, including spermatogenesis, metabolism and stem cell ...self-renewal and differentiation. Here, we found that JMJD1A knockdown in prostate cancer cells antagonizes their proliferation and survival. Profiling array analyses revealed that JMJD1A-dependent genes function in cellular growth, proliferation and survival, and implicated that the c-Myc transcriptional network is deregulated following JMJD1A inhibition. Biochemical analyses confirmed that JMJD1A enhances c-Myc transcriptional activity by upregulating c-Myc expression levels. Mechanistically, JMJD1A activity promoted recruitment of androgen receptor (AR) to the c-Myc gene enhancer and induced H3K9 demethylation, increasing AR-dependent transcription of c-Myc mRNA. In parallel, we found that JMJD1A regulated c-Myc stability, likely by inhibiting HUWE1, an E3 ubiquitin ligase known to target degradation of several substrates including c-Myc. JMJD1A (wild type or mutant lacking histone demethylase activity) bound to HUWE1, attenuated HUWE1-dependent ubiquitination and subsequent degradation of c-Myc, increasing c-Myc protein levels. Furthermore, c-Myc knockdown in prostate cancer cells phenocopied effects of JMJD1A knockdown, and c-Myc re-expression in JMJD1A-knockdown cells partially rescued prostate cancer cell growth in vitro and in vivo. c-Myc protein levels were positively correlated with those of JMJD1A in a subset of human prostate cancer specimens. Collectively, our findings identify a critical role for JMJD1A in regulating proliferation and survival of prostate cancer cells by controlling c-Myc expression at transcriptional and post-translational levels.
Acetylation of the RelA subunit of NF-κB at lysine-310 regulates the transcriptional activation of NF-κB target genes and contributes to maintaining constitutively active NF-κB in tumors. ...Bromodomain-containing factor Brd4 has been shown to bind to acetylated lysine-310 (AcLys310) and to regulate the transcriptional activity of NF-κB, but the role of this binding in maintaining constitutively active NF-κB in tumors remains elusive. In this study, we demonstrate the structural basis for the binding of bromodomains (BDs) of bromodomain-containing protein 4 (Brd4) to AcLys310 and identify the BD inhibitor JQ1 as an effective small molecule to block this interaction. JQ1 suppresses TNF-α-mediated NF-κB activation and NF-κB-dependent target gene expression. In addition, JQ1 inhibits the proliferation and transformation potential of A549 lung cancer cells and suppresses the tumorigenicity of A549 cells in severe combined immunodeficiency mice. Furthermore, we demonstrate that depletion of Brd4 or treatment of cells with JQ1 induces the ubiquitination and degradation of the constitutively active nuclear form of RelA. Our results identify a novel function of Brd4 in maintaining the persistently active form of NF-κB found in tumors, and they suggest that interference with the interaction between acetylated RelA and Brd4 could be a potential therapeutic approach for the treatment of NF-κB-driven cancer.
Novel mechanisms for electromagnetic wave emission in the terahertz frequency regime emerging at the nanometer scale have recently attracted intense attention for the purpose of searching ...next-generation broadband THz emitters. Here, we report broadband THz emission, utilizing the interface inverse Rashba-Edelstein effect. By engineering the symmetry of the Ag/Bi Rashba interface, we demonstrate a controllable THz radiation (∼0.1-5 THz) waveform emitted from metallic Fe/Ag/Bi heterostructures following photoexcitation. We further reveal that this type of THz radiation can be selectively superimposed on the emission discovered recently due to the inverse spin Hall effect, yielding a unique film thickness dependent emission pattern. Our results thus offer new opportunities for versatile broadband THz radiation using the interface quantum effects.
Abstract
We present the results of a multiwavelength investigation of the very X-ray luminous galaxy cluster MACSJ0553.4−3342 (z = 0.4270; hereafter MACSJ0553). Combining high-resolution data ...obtained with the Hubble Space Telescope and the Chandra X-ray Observatory with ground-based galaxy spectroscopy, our analysis establishes the system unambiguously as a binary, post-collision merger of massive clusters. Key characteristics include perfect alignment of luminous and dark matter for one component, a separation of almost 650 kpc (in projection) between the dark-matter peak of the other subcluster and the second X-ray peak, extremely hot gas (kT > 15 keV) at either end of the merger axis, a potential cold front in the east, an unusually low gas mass fraction of approximately 0.075 for the western component, a velocity dispersion of
$1490_{-130}^{+104}$
km s−1, and no indication of significant substructure along the line of sight. We propose that the MACSJ0553 merger proceeds not in the plane of the sky, but at a large inclination angle, is observed very close to turnaround, and that the eastern X-ray peak is the cool core of the slightly less massive western component that was fully stripped and captured by the eastern subcluster during the collision. If correct, this hypothesis would make MACSJ0553 a superb target for a competitive study of ram-pressure stripping and the collisional behaviour of luminous and dark matter during cluster formation.
AlxCrFeNi eutectic multi-component alloys were prepared to obtain excellent mechanical properties by double-phase strengthening. The X-ray diffraction results showed that the crystal structure were ...both body-centered cubic and energy-dispersive X-ray spectrometer identified that the two phases are ordered NiAl intermetallic and disordered Fe, Cr solid solution. The formation of eutectic structures was introduced by a simplified dynamic model. After mechanical tests, the alloys presented excellent compressive strength and unexpected large deformation. Due to the solid solution and fine-grain strengthening resulted by Al addition, mechanical properties of AlxCrFeNi alloys exhibited regularity in some degree. Among all alloys, Al1.3CrFeNi has the highest fracture strength and Al0.9CrFeNi has the most excellent strain. Besides, Al1.2CrFeNi alloy showed a good combination of strength and ductility.
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