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C30H72N10O7S2, triclinic, P1̄ (no. 2), a = 8.75510(10) Å, b = 15.1170(2) Å, c = 16.8843(2) Å, α = 76.272 ( 1 ) ° $76.272(1){}^{\circ}$ , β = 78.397 ( 1 ) ° $78.397(1){}^{\circ}$ , γ = 88.277 ( 1 ) ° $88.277(1){}^{\circ}$ , V = 2126.09(5) Å3, Z = 2, R gt(F) = 0.0407, wR ref(F 2) = 0.1282, T = 296(2) K.

This report studies the charge-based sensing modality of FET-embedded nanopore biosensors through FEM simulation. PNP equation is solved to analyze the mirror charge introduced by charged biomolecule while threading through the nanopore-FET sensor. Negative and positive charged molecules are analyzed respectively. Obvious local potential change induced by the presenting of charged molecules nearby is observed. In addition, the transport-induced descreening effect is observed under intensive bias, which might explain the capability of charge sensing even under high concentrations such as 1 M for FET-nanopore biosensors.

Riboflavin serves as the direct precursor of the FAD/FMN coenzymes and is biosynthesized in most prokaryotes, fungi and plants. Fungal Rib2 possesses a deaminase domain for deamination of pyrimidine in the third step of riboflavin biosynthesis. Here, four high-resolution crystal structures of a Rib2 deaminase from Aspergillus oryzae (AoRib2) are reported which display three distinct occluded, open and complex forms that are involved in substrate binding and catalysis. In addition to the deaminase domain, AoRib2 contains a unique C-terminal segment which is rich in charged residues. Deletion of this unique segment has no effect on either enzyme activity or protein stability. Nevertheless, the C-terminal αF helix preceding the segment plays a role in maintaining protein stability and activity. Unexpectedly, AoRib2 is the first mononucleotide deaminase found to exist as a monomer, perhaps due to the assistance of its unique longer loops (Lβ1–β2, LαB–β3 and LαC–β4). These results form the basis for a molecular understanding of riboflavin biosynthesis in fungi and might assist in the development of antibiotics.

Two novel metal–organic coordination complexes based on L [L = 3,6-bis(imidazol-1-yl)pyridazine], which could also be called as [Ni(L)(1,3,5-H2BTC)2H2O]n 1 (1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid) and {[Ni2(L)(2,6-PYDC)2(H2O)2]·5H2O}n 2 (2,6-H2PYDC = 2,6-pyridine dicarboxylic acid) have been formed using solvothermal method by reaction of Ni(II) salts with the L ligand in the presence of different carboxylate ligands (1,3,5-H3BTC for 1 and 2,6-H2PYDC for 2). The treatment activity of compounds 1 and 2 on the neonatal hypoxic-ischemic encephalopathy was estimated, then the relevant mechanism was discussed. Firstly, the quantity of the tumor necrosis factor-α (TNF-α) and neuron-specific enolase (NSE) in the cerebrospinal fluid was measured by enzyme linked immunosorbent assay (ELISA) detection kit. In addition to this, the expression levels of the glutamate receptor on the brain nerve cells were estimated by real time reverse transcription-polymerase chain reaction (RT-PCR).

A three-dimensional (3D) metal–organic framework [(CH3)2NH2][Zn2(DMTDC)2(3-mtz)]·4DMF·3H2O (Zn-MOF) has been solvothermally synthesized by using mixed ligands of 3-methyl-1,2,4-triazole (3-Hmtz) and a thiophene-functionalized dicarboxylate ligand, 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid (H2DMTDC). Zn-MOF exhibits a uninodal 6-connected pcu α-Po topology structure and possesses an anionic framework with large 1D-trapezoidal channels. Gas adsorption studies reveal that the activated Zn-MOF-a displays selective adsorption of CO2 over N2 at 273 K and 298 K as well as a high isosteric heat of CO2 adsorption. Moreover, Zn-MOF shows selective adsorption of the cationic dyes over the anionic and neutral dyes, and can be used as a fast-response and sensitive probe for the detection of Fe3+ by fluorescence quenching after encapsulation of Tb3+ into the pores by postsynthetic cation exchange.

The prediction of non-trivial topological electronic states hosted by half-Heusler compounds makes them prime candidates for discovering new physics and devices as they harbor a variety of electronic ground states including superconductivity, magnetism, and heavy fermion behavior. Here we report normal state electronic properties of a superconducting half-Heusler compound YPtBi using angle-resolved photoemission spectroscopy (ARPES). Our data reveal the presence of a Dirac state at the zone center of the Brillouin zone at 500 meV below the chemical potential. We observe the presence of multiple Fermi surface pockets including two concentric hexagonal and six half oval shaped pockets at the gamma and K points of the Brillouin zone, respectively. Furthermore, our measurements show Rashba-split bands and multiple surface states crossing the chemical potential which are supported by the first-principles calculations. Our finding of a Dirac state in YPtBi plays a significant role in establishing half-Heusler compounds as a new potential platform for novel topological phases and explore their connection with superconductivity., 6 pages, 4 figures

A new triazine charring agent, melamine formaldehyde resin modified with pentaerythritol (named as MF-MPOL), was synthesized through hydroxymethylation, condensation and etherification by using melamine, paraformaldehyde and pentaerythritol as raw materials, and characterized by solid-state 13C NMR and FT-IR. The intumescent flame retardant (IFR) consisting of MF-MPOL with ammonium polyphosphate has good flame retardancy in polypropylene (PP). The analysis of the residues obtained in cone calorimetry test showed that the IFR played a role of flame retardancy mainly in condensed phase. In other words, the porous and dense - continuous intumescent char layer formed during the burning process results in flame retardant effect by insulation of heat, oxygen and preventing the underlying PP from degradation and volatilization of pyrolytic products.

At present, most of the studies of the stability of the formation-cement sheath-casing combination have been mainly based on the plane, and the three-dimensional model established is only one example. There is no systematic study of the influence of physical parameters and process parameters on the stability of the combined body under the three-dimensional model and the action of triaxial crustal stress. Through the establishment of three-dimensional formation-cement sheath-casing linear elastic combination model, we can study the influence of operational parameters (cement sheath pressure, casing cross section pressure, inner casing pressure, ellipticity of borehole, centrality of casing, thickness of cement sheath) by the two interfaces’ Von Mises stress and the total displacement of the combination body. It is pointed out that the pressure of cement sheath, and casing cross section pressure have no effect on the stability of formation, cement sheath and casing; The higher the ellipticity of the borehole, the eccentricity of the casing (position 1, 2) and the thickness of the cement sheath, the higher the stability of the second interface of the cementing; The higher the inner casing pressure and the eccentricity of the casing(position 3), the lower the stability of the second interface of the cementing; The higher the eccentricity of the casing (position 2,3) and the thickness of the cement sheath, the higher the stability of the first interface of the cementing; The higher the inner casing pressure, the eccentricity of the casing (position 1) and the ellipticity of the borehole, the lower the stability of the first interface of the cementing; The higher the eccentricity of the casing (position 2,3) and thickness of the cement sheath, the higher the stability of the casing; The higher the inner casing pressure, the ellipticity of the borehole and the eccentricity of the casing(position 1), the lower the stability of the casing. Through this study, according to the formation stress, the formation physical parameters (elastic modulus, Poisson's ratio, density), optimize the operational parameters, ensure the long-term integrity of the combination.

Three new alkaline earth metal–organic frameworks (MOFs), namely [Mg2(DMTDC)2(DMF)3(H2O)2]·2DMF·2H2O (1), [Ca(DMTDC)(DMF)] (2) and [Sr(DMTDC)(DMF)] (3), have been synthesized under solvothermal conditions by using a thiophene-functionalized dicarboxylate ligand, 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid (H2DMTDC). Single-crystal X-ray diffraction analyses demonstrate that the metal ion radii play an important role in coordination numbers and topologies, i.e., hexa-coordinated Mg2+ in 1 gives a two-dimensional layered framework with an sql net, while octa-coordinated Ca2+/Sr2+ in 2/3 exhibit a three-dimensional framework with lvt nets. All frameworks show a one-dimensional rhombus-shaped channel that is occupied by DMF and/or water molecules. Photoluminescence studies reveal that 1–3 can be used as fast-response fluorescence sensors for the sensitive detection of Fe3+ ions with favorable recyclability through fluorescence quenching.

The electronic property and magnetic susceptibility of Ce3Pd3Bi4 were systemically investigated from 18 to 290 K for varying values of cell volume using dynamic mean-field theory coupled with density functional theory. By extrapolating to zero temperature, the ground state of Ce3Pd3Bi4 at ambient pressure is found to be a correlated semimetal due to insufficient hybridization. Upon applying pressure, the hybridization strength increases and a crossover to the Kondo insulator is observed at finite temperatures. The characteristic temperature signaling the formation of Kondo singlet, as well as the characteristic temperature associated with f-electron delocalization–localization change, simultaneously vanishes around a critical volume of 0.992 V0, suggesting that such metal–insulator transition is possibly associated with a quantum critical point. Finally, Wilson’s loop calculations indicate that the Kondo insulating side is topologically trivial, thus a topological transition also occurs across the quantum critical point.

The discovery of two-dimensional (2D) van der Waals (vdW) materials often provides interesting playgrounds to explore novel phenomena. One of the missing components in 2D vdW materials is the intrinsic heavy-fermion systems, which can provide an additional degree of freedom to study quantum critical point (QCP), unconventional superconductivity, and emergent phenomena in vdW heterostructures. Here, we investigate 2D vdW heavy-fermion candidates through the database of experimentally known compounds based on dynamical mean-field theory calculation combined with density functional theory (DFT+DMFT). We have found that the Kondo resonance state of CeSiI does not change upon exfoliation and can be easily controlled by strain and surface doping. Our result indicates that CeSiI is an ideal 2D vdW heavy-fermion material and the quantum critical point can be identified by external perturbations.

Magnetic proximity interactions (MPIs) between atomically-thin semiconductors and two-dimensional magnets provide a means to manipulate spin and valley degrees of freedom in nonmagnetic monolayers, without the use of applied magnetic fields. In such van der Waals (vdW) heterostructures, MPIs originate in the nanometer-scale coupling between the spin-dependent electronic wavefunctions in the two materials, and typically their overall effect is regarded as an effective magnetic field acting on the semiconductor monolayer. Here we demonstrate that this picture, while appealing, is incomplete: The effects of MPIs in vdW heterostructures can be markedly asymmetric, in contrast to that from an applied magnetic field. Valley-resolved optical reflection spectroscopy of MoSe$_{2}$/CrBr$_{3}$ vdW structures reveals strikingly different energy shifts in the $K$ and $K'$ valleys of the MoSe$_2$, due to ferromagnetism in the CrBr$_3$ layer. Strong asymmetry is observed at both the A- and B-exciton resonances. Density-functional calculations indicate that valley-asymmetric MPIs depend sensitively on the spin-dependent hybridization of overlapping bands, and as such are likely a general feature of such hybrid vdW structures. These studies suggest routes to selectively control \textit{specific} spin and valley states in monolayer semiconductors., Comment: 12 pages total (including 4 figures + 7 Supplemental Figures)

Removing particles dispersed in fluid through drops is widely presented in various fields, and the critical factor is particles captured by droplets. Drop rotation effects play a dominant role in the capture process. However, their influences on collection characteristics remain unclear. Thus, a particle collection model was developed to simultaneously consider rotation and translation effects on fine particles captured by an individual droplet. The finite volume method was used to solve for flow field and collection efficiency, and the proposed model was verified by comparison with experimental and published results. The Liutex method was used to identify the vortex structure, on which dimensionless droplet rotation rates ranged from 0 to 0.1. Velocity, drag coefficient, radial position, and captured particle velocity distribution and collection efficiency were also investigated in relation to the rotation effect. The results show that the established model is reasonable. Vortex strength increases with increased rotation speed where the increment can be up to 480, and fluid rotation strength depends on the competitive relation between the increase in the rotation rate and the vortex movement. Radial velocity increases in regions where the angle between the positive x axis and the normal vector of drop surface ranges from 115° to 180° but decreases in regions where the angle ranges from −180° to −120°, and corresponding regions produce a comparative relation for improving particle capture. Increasing the rotation rate can increase the drag force coefficient by about 0.025, hindering droplet–particle collision. Average radial velocity of particles with higher than 3.7 mm/s is necessary at high rotation rates, while collection efficiency decreases at increased droplet rotation rates.

C11H27N5O4S, triclinic, P 1 ‾ $\overline{1}$ (no. 2), a = 7.8359 (2) Å, b = 8.6966 (3) Å, c = 12.9907(4) Å, α = 92.047 (2)°, β = 92.041 (2)°, γ = 96.087 (2)°, V = 879.02 (5) Å3, Z = 2, R gt (F) = 0.0412, wR ref (F 2) = 0.1265, T = 298 K.

Antiferromagnetism in a prototypical quantum critical metal ${\mathrm{CeCoIn}}_{5}$ is known to be induced by slight substitutions of nonmagnetic Zn atoms for In. In nominally 7% Zn-substituted ${\mathrm{CeCoIn}}_{5}$, an antiferromagnetic (AFM) state coexists with heavy fermion superconductivity. Heterogeneity of the electronic states is investigated in Zn-doped ${\mathrm{CeCoIn}}_{5}$ by means of nuclear quadrupole and magnetic resonances (NQR and NMR). Site-dependent NQR relaxation rates $1/{T}_{1}$ indicate that the AFM state is locally nucleated around Zn substituents in the matrix of a heavy fermion state, and percolates through the bulk at the AFM transition temperature ${T}_{\mathrm{N}}$. At lower temperatures, an anisotropic superconducting (SC) gap below the SC transition temperature ${T}_{\mathrm{c}}$, and the SC state permeates through the AFM regions via a SC proximity effect. Applying an external magnetic field induces a spin-flop transition near 5 T, reducing the volume of the AFM regions. Consequently, a short-ranged inhomogeneous AFM state survives and coexists with a paramagnetic Fermi liquid state at high fields.

In this paper, a direct co-precipitation method was used to prepare antimony-doped calcium fluoride nanopowders (NPs). The effects of reaction concentration, reaction medium and lanthanum doping on the properties of calcium fluoride NPs were investigatedviaa control variable method and the best preparation conditions was identified. The structural analysis of the powder materials prepared in this work were carried out by XRD, SEM, ICP and other test methods. By analyzing the experimental data, we found that the best performance of Eu-doped CaF2NPs can be acquired under the reaction concentration of 1 mol/L in aqueous solution. In the same time, the NPs possess a high degree of dispersion with an average diameter of 22 nm, which is beneficial to the preparation of transparent Eu3+: CaF2ceramics with excellent up-conversion luminescence. The results show that the grain size, the crystallinity of the NPs and the amount of Eu infiltration have a decreasing tendency with the increasing reaction concentration, while the degree of agglomeration of the NPs can be enhanced by increasing the reaction concentration.

We study adsorption behaviors of isomorphic metal-doped metal-organic frameworks in the field of dyeing wastewater treatment technology. Herein, a series of 3D isostructural Co2+/Cd2+ metal-doped metal-organic frameworks named compounds 1–5 were successfully synthesized under hydrothermal conditions and used in adsorbing and separation dyes. We demonstrate that dye molecules can be adsorbed on the external surface of the MOFs and their loadings can be tuned by adjusting the rate of the central metal atoms. We show that compound 5 crystals containing Cd2+ are selective adsorbent for pH, temperature, ionic strength responsive adsorption. Their adsorptive properties of cationic dyes in aqueous solutions are higher than that of neutral and anionic dyes. Our method of isomorphic metal-doped opens new possibilities to construct adsorption strength regulation systems for a wide range of applications and facilitates new efforts in environmental purification.

Vacuum brazing of FeCrMo damping alloy is carried out by using Mn Ni Cu Cr Co brazing filler at 1080 °C for different times (5, 15, 30, 60, and 120 min). The results reveal that the joint's interfacial microstructure brazed for 15 min consists of three zones: the FeCrMo substrate, Fe solid solution layer, and a brazing seam consisting of a (Mn, Ni) solid solution. Kirkendall vacancies are observed in the brazing seam when the joint is brazed for 120 min, due to the fact that Fe diffuses more quickly than Ni, Cu, and Mn. The specimen manifests the most optimal damping capacity when brazed for 60 min, and its lap-shear strength still reaches 426.7 MPa. The detailed mechanisms behind the formation of different phases across the brazed joint and their correlations with joint strength and damping capacity are also discussed.

While bismuth ferrite BiFeO3 (BFO) is a well studied multiferroic material, its electronic and magnetic properties in the presence of A-site dopants have not been explored widely. Here we report the results of a systematic study of the local electronic structure, spontaneous polarization, and magnetic properties of lanthanum (La) and strontium (Sr) doped rhombohedral bismuth ferrite within density functional theory. An enhanced ferroelectric polarization of 122.43 μC/cm2 is predicted in the uniformly doped BiLaFe2O6. We find that substitution of Sr in the A-site drives the system into a metallic state. The nature of magnetism arises mainly from the B-site Fe exhibiting a G-type antiferromagnetic ordering. Our study finds that upon dopant substitution, the local magnetic moment is decreased and its magnitude is dependent on the distance between the Fe and the dopant atom. The correlation between the local moment and the distance between the Fe and the dopant atom is discussed.

Electron correlations play a central role in iron-based superconductors. In these systems, multiple Fe $3d$-orbitals are active in the low-energy physics, and they are not all degenerate. For these reasons, the role of orbital-selective correlations has been an active topic in the study of the iron-based systems. In this paper, we survey the recent developments on the subject. For the normal state, we emphasize the orbital-selective Mott physics that has been extensively studied, especially in the iron chalcogenides, in the case of electron filling $n \sim 6$. In addition, the interplay between orbital selectivity and electronic nematicity is addressed. For the superconducting state, we summarize the initial ideas for orbital-selective pairing, and discuss the recent explosive activities along this direction. We close with some perspectives on several emerging topics. These include the evolution of the orbital-selective correlations, magnetic and nematic orders and superconductivity as the electron filling factor is reduced from $6$ to $5$, as well as the interplay between electron correlations and topological bandstructure in iron-based superconductors., Comment: 26 pages, 8 figures

C26H54N10O3S3, monoclinic, Pc (no. 7), a = 8.5247(5) Å, b = 10.6658(5) Å, c = 21.2970(10) Å, β = 109.472(2)°, V = 1825.63(16) Å3, Z = 2, R gt(F) = 0.0366, wR ref(F 2) = 0.0866, T = 298 K.

We performed optical-pump, terahertz-probe measurements on optimally doped La2 − x Sr x CuO4 under an applied magnetic field. T his r eveals t he s trong interplay between magnetic and optical Cooper pair breaking that governs quasiparticle recovery dynamics in superconducting cuprates.

C12H18N8O4S2, monoclinic, P21/c (no. 14), a = 13.378(4) Å, b = 5.0129(14) Å, c = 13.396(4) Å, β = 96.118(4)°, V = 893.3(4) Å3, Z = 2, R gt (F) = 0.0561, wR ref (F 2) = 0.1201, T = 298 K.

Fast and dynamical control of quantum phases is highly desired in the application of quantum phenomena in devices. On the experimental side, ultrafast laser pulses provide an ideal platform to induce femtosecond dynamics in a variety of materials. Here, we show that a laser pulse driven heavy fermion system, can be tuned to dynamically evolve into a phase, which is not present in equilibrium. Using the state-of-the-art time-dependent variational Monte Carlo method, we perform numerical simulations of realistic laser pulses applied to the Kondo Lattice model. By tracking spin and charge degrees of freedom we identify a dynamical phase transition from a charge ordered into a metallic state, while preserving the spin order of the system. We propose to use higher harmonic generation to identify the dynamical phase transition in an ultrafast experiment., Comment: 6 pages, 5 figures + supplemental material, comments are welcome

We predict that CeBi in the ferromagnetic state is a Weyl semimetal. Our calculations within density functional theory show the existence of two pairs of Weyl nodes on the momentum path $(0, 0, k_z)$ at $15$ meV} above and $100$ meV below the Fermi level. Two corresponding Fermi arcs are obtained on surfaces of mirror-symmetric (010)-oriented slabs at $E=15$ meV and both arcs are interrupted into three segments due to hybridization with a set of trivial surface bands. By studying the spin texture of surface states, we find the two Fermi arcs are strongly spin-polarized but in opposite directions, which can be detected by spin-polarized ARPES measurements. Our theoretical study of quasiparticle interference (QPI) for a nonmagnetic impurity at the Bi site also reveals several features related to the Fermi arcs. Specifically, we predict that the spin polarization of the Fermi arcs leads to a bifurcation-shaped feature only in the spin-dependent QPI spectrum, serving as a fingerprint of the Weyl nodes., 9 pages with 9 embedded figures. Supplemental material shortened

Plutonium is a critically important material as the behavior of its $5f$ electrons stands midway between the metalliclike itinerant character of the light actinides and localized atomic-core-like character of the heavy actinides. The $\ensuremath{\delta}$ phase of plutonium ($\ensuremath{\delta}$-Pu), whereas still itinerant, has a large coherent Kondo peak and strong electronic correlations coming from its near-localized character. Using sophisticated Gutzwiller wave function and dynamical mean-field theory correlated theories, we study the Fermi surface and associated mass renormalizations of $\ensuremath{\delta}$-Pu together with calculations of the de Haas--van Alphen frequencies. We find a large ($\ensuremath{\sim}200%$) correlation induced volume expansion in both the hole and the electron pockets of the Fermi surface in addition to an intermediate mass enhancement. All of the correlated electron theories predict, approximately, the same hole pocket placement in the Brillouin zone, which is different from that obtained in conventional density-functional band-structure theory, whereas the electron pockets from all theories are in, roughly, the same place.

Symmetry plays a central role in conventional and topological phases of matter, making the ability to optically drive symmetry change a critical step in developing future technologies that rely on such control. Topological materials, like the newly discovered topological semimetals, are particularly sensitive to a breaking or restoring of time-reversal and crystalline symmetries, which affect both bulk and surface electronic states. While previous studies have focused on controlling symmetry via coupling to the crystal lattice, we demonstrate here an all-electronic mechanism based on photocurrent generation. Using second-harmonic generation spectroscopy as a sensitive probe of symmetry change, we observe an ultrafast breaking of time-reversal and spatial symmetries following femtosecond optical excitation in the prototypical type-I Weyl semimetal TaAs. Our results show that optically driven photocurrents can be tailored to explicitly break electronic symmetry in a generic fashion, opening up the possibility of driving phase transitions between symmetry-protected states on ultrafast time scales., 28 pages, 15 figures, 4 Tables

Weyl semimetals have been the focus of intense experimental and theoretical investigation, due to their broad appeal in fundamental science and applied technology alike. More recently, several studies have centered on the nonlinear optical properties of these materials, where it is believed that characteristic features of Weyl physics can be observed. To date, these studies have been limited to static or quasi-static measurements, but new and important insights can come about through extending these nonlinear optical spectroscopies into the time domain. To do so, we use terahertz (THz) emission spectroscopy and time-resolved second harmonic generation (TR-SHG) spectroscopy to provide a contact free measure of ultrafast photocurrent dynamics in the transition metal monopnictide family of type-I Weyl semimetals. On the basis of our data, we are able to clearly distinguish between helicity-dependent photocurrents generated within the ab-plane and polarization-independent photocurrents flowing along the non-centrosymmetric c-axis. Such findings are consistent with earlier static photocurrent experiments, and demonstrate on the basis of both the physical constraints imposed by symmetry and the temporal dynamics intrinsic to current generation and decay that optically induced photocurrents in TaAs are inherent to the underlying crystal symmetry. Such generality in the microscopic origin of photocurrent generation in the transition metal monopnictide family of Weyl semimetals makes these materials promising candidates as next generation sources or detectors in the mid-IR and THz frequency ranges.

We study the thickness dependence of the electronic, magnetic, and optical properties of a NiPS$_3$ thin film, an antiferromagnetic charge-transfer insulator. Utilizing state-of-the-art advanced density functionals, we find the antiferromagnetic Zig-Zag order, the band gap, and the main peaks in the dielectric tensor are all in good agreement with the corresponding experimental values. Upon thinning, the Zig-Zag antiferromagnetic order becomes virtually degenerate with a competing N\'eel order, consistent with the suppression of long-range order observed by Raman spectroscopy due to strong magnetic fluctuations. Additionally, due to the robustness of the electronic band gap observed by spectroscopic ellipsometry measurements above $T_N$, we suggest that the persistence of the band gap is driven by strong electronic correlations. Other systematic changes in electronic dispersion, effective mass, and Kerr angle with thickness are also discussed. Finally, an applied external electric field is found to suppress the band gap by up to 13%, until precipitating an insulator-metal transition at a critical field value of $0.7$ eV/\r{A}., Comment: 9 pages, 7 figures

We present an $\textit{ab initio}$ study of the excitonic states of a prototypical high-temperature superconductor La$_2$CuO$_4$ and compare them to the isostructural single-layer nickelate La$_2$NiO$_4$. Key difference in the low-energy electronic structure leads to very different excitonic behavior. Excitons in La$_2$CuO$_4$ are delocalized and can freely move in the CuO$_2$ plane without disturbing the antiferromagnetic order. In contrast, in La$_2$NiO$_4$ we find the low-lying excitonic states to be extremely localized, producing a nearly flat dispersion. The theoretically obtained excitonic dispersion and behavior are in excellent agreement with RIXS observations. To classify the excitons we project the electron-hole coupling onto each atomic site including the full manifold of atomic orbitals. We find the excitons to be composed of a linear combination of exciton classes, including Mott-Hubbard, $d-d$, and charge-transfer. The implication of these excitations to the high-$T_c$ pairing mechanism is also discussed., 11 pages, 4 figures

We utilized ultrafast X-ray diffraction to investigate optically induced strain waves in the Weyl semimetal TaAs, revealing real-time structural oscillations originating from quasilongitudinal and quasi-shear acoustic phonon modes.

We report the electronic and magnetic properties of stoichiometric ${\mathrm{CeAuBi}}_{2}$ single crystals. At ambient pressure, ${\mathrm{CeAuBi}}_{2}$ orders antiferromagnetically below a N\'eel temperature (${T}_{N}$) of 19 K. Neutron diffraction experiments revealed an antiferromagnetic propagation vector $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\tau}}=[0,0,1/2]$, which doubles the paramagnetic unit cell along the $c$ axis. At low temperatures several metamagnetic transitions are induced by the application of fields parallel to the $c$ axis, suggesting that the magnetic structure of ${\mathrm{CeAuBi}}_{2}$ changes as a function of field. At low temperatures, a linear positive magnetoresistance may indicate the presence of band crossings near the Fermi level. Finally, the application of external pressure favors the antiferromagnetic state, indicating that the $4f$ electrons become more localized.

Since tantalum arsenide (TaAs) has been experimentally verified as a Weyl semimetal, intensive research has been devoted to study of the unique properties of the material. Despite this, the ultrafast dynamics of TaAs is still not very well understood. In this work, we study the relaxation dynamics in TaAs using transient reflection spectroscopy. From the transient reflection measurement, we observe either a single (fast) or a dual (fast and slow) relaxation, depending on the probing wavelength. The additional relaxation channel is attributed to an asymmetric population of photoexcited electrons and holes. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Accepted version Ministry of Education (MOE): AcRF Tier 1 MOE2018-T1-1-097 Ministry of Education (MOE): AcRF Tier 1 RG95/19 (S) Ministry of Education (MOE): Tier 3 (MOE2018-T3-1-002) A*STAR PHAROS Programme on 2D Materials: SERC 152 70 00016

We demonstrate a significant pump helicity dependence in the amplitude of coherent Raman active phonon oscillations in the van der Waals magnet CrI3, revealing a strong non-equilibrium coupling between spin and structural order.

Spin-triplet superconductors are of extensive current interest because they can host topological state and Majorana ferimons important for quantum computation. The uranium based heavyfermion superconductor UTe$_2$ has been argued as a spin-triplet superconductor similar to UGe$_2$, URhGe, and UCoGe, where the superconducting phase is near (or coexists with) a ferromagnetic (FM) instability and spin-triplet electron pairing is driven by FM spin fluctuations. Here we use neutron scattering to show that although UTe$_2$ exhibits no static magnetic order down to 0.3 K, its magnetism is dominated by incommensurate spin fluctuations near antiferromagnetic (AF) ordering wave vector and extends to at least 2.6 meV. We are able to understand the dominant incommensurate spin fluctuations of UTe$_2$ in terms of its electronic structure calculated using a combined density functional and dynamic mean field theory., Comment: 6 pages, 4 figures, submitted for publication on July 5th

Chromatographic stationary phases with specific capturing phosphoproteins is widely used in biological sample pretreatment. However, when captured protein is released, it is required to change the pH of the mobile phase or to use an eluent. Usually, the mobile phase or eluent are salt solutions with high concentration and extreme pH or toxic organic reagents. In this situation, these reagents will destroy the activity and structure of phosphorylated proteins. In addition, the mobile phase after switching the column takes longer time to restore the balance, reducing the experimental efficiency. In order to solve the these problems, we introduce temperature-reponsive materials into the chromatographic stationary phase to achieve the capture and release of phosphorylated proteins by changing the temperature only, in which we use water as the mobile phase. This approach overcomes the drawbacks of traditional methods, and makes the separation process safe and simple. Based on the surface initiated Reversible Addition Fragmentation Chain Transfer Polymerization (SI-RAFT) method, silica@pNIPAAm-nanoTiO2, a kind of Metal Oxide Affinity Chromatography, was synthesized by the rapid introduction of functional groups. The synthesis of silica@pNIPAAm-nanoTiO2was confirmed by infrared and X-ray photoelectron spectroscopy. The grafting rate and the lowest critical temperature were measured by TG and DSC. The results showed that the material had qualified temperature-sensitive properties. The grafting conformation and mobile phase pH of the material were optimized before testing the properties and found that when the material grafting ratio was 10% -15%, the graft density was 30%, and the mobile phase pH was 6, it had the best separate effect. Finally, the material successfully achieved the capture and release of adenosine triphosphate and casein phosphopeptides.

The porous silicon nitride ceramics with low dielectric constant and high flexural strength were obtained by adding pore-forming agent through partial sintering technique. The effects of pore-forming agent amount on the properties of porous silicon nitride ceramics were investigated. Microstructure was analyzed by means of scanning electron microscopy. The results show that the porous structure is formed by the overlap of pillar β-Si3N4 with high length diameter ratio. The porosity of samples rises with the increase of pore-forming agent content, which leads to the decrease of the dielectric constant and loss, but the decrease of flexural strength. When the pore-forming agent of PMMA with mass fraction of 20% was added, the volume density, porosity, dielectric constant and loss of porous silicon nitride ceramics were 1.17g/cm3, 66.5%, 2.33 and 0.8×10-3 respectively, with higher flexural strength of 75MPa which is satisfactory as low dielectric material for core layer of broadband radome.

Si3N4-BaTiO3 composite ceramics, a type of high dielectric materials applied in the multifunction radome, were prepared by gas pressure-sintering method. The influences of BaTiO3 power content on the mechanical performances, dielectric properties and microstructure of Si3N4-BaTiO3 composite ceramics were investigated. The results showed that the sintering density, the elastic modulus and the flexural strength of Si3N4-BaTiO3 composite ceramics all firstly increased and then decreased along with the increase of BaTiO3 power in sample. Meanwhile, Relationship between BaTiO3 power content and dielectric properties of Si3N4-BaTiO3 composite ceramics within the frequency range of 8.2–12.4 GHz (X-band) was studied. The average of dielectric constant e of Si3N4-BaTiO3 composite ceramics increased from 7.33 to 9.98 and the average of dielectric loss tand increased from 2.8 ´ 10-3 to 0.0168 when the content of BaTiO3 power increased from 0 to 25 wt.%. The increase of the dielectric properties of Si3N4–BaTiO3 composite ceramics were attributed to the electronic and molecular polarization at interface between Si3N4 and BaTiO3, compared with the pure matrix Si3N4.

Two lanthanide–organic frameworks formulated as [Eu2(DMTDC)3(DEF)4]·DEF·6H2O (1) and [Tb2(DMTDC)3(DEF)4]·DEF·6H2O (2) (H2DMTDC = 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid and DEF = N,N-diethylformamide) have been synthesized under solvothermal conditions by using a bithiophene dicarboxylate organic ligand, H2DMTDC. Compounds 1 and 2 are isomorphous and feature 3D frameworks with uninodal six-connected pcu α-Po topology structures. The systematic luminescence experiments reveal that 1 and 2 can be used as fast-response fluorescence sensors for the sensitive detection of nitrobenzene and Fe3+ ions with favorable recyclability through fluorescence quenching.