4-(4-Oxopent-2-en-2-yl­amino)-1,2,4-triazol-1-ium-5-thiol­ate

In the title compound, C8H12N4OS, an intra­molecular N—H⋯O hydrogen bond links the imine N atom to the oxo O atom. In the crystal, mol­ecules are linked by inter­molecular N—H⋯O and N—H⋯S hydrogen bonds, forming a two-dimensional framework

Poly[(μ5-2,6-dimethyl­pyridine-3,5-dicarboxyl­ato)zinc]

In the polymeric title complex, [Zn(C9H7NO4)]n, the ZnII cation is located on a twofold rotation axis and is coordinated by five 2,6-dimethyl­pyridine-3,5-dicarboxyl­ate (mpdc) anions in a distorted ZnNO4 trigonal–bipyramidal geometry. The mpdc anion is also located on the twofold rotation axis and bridges five ZnII cations, forming the three-dimensional polymeric complex. Weak C—H⋯π inter­actions are present in the crystal structure

Efficient generation of relativistic near-single-cycle mid-infrared pulses in plasmas

Ultrashort intense optical pulses in the mid-infrared (mid-IR) region are very important for broad applications ranging from super-resolution spectroscopy to attosecond X-ray pulse generation and particle acceleration. However, currently, it is still difficult to produce few-cycle mid-IR pulses of relativistic intensities using standard optical techniques. Here, we propose and numerically demonstrate a novel scheme to produce these mid-IR pulses based on laser-driven plasma optical modulation. In this scheme, a plasma wake is first excited by an intense drive laser pulse in an underdense plasma, and a signal laser pulse initially at the same wavelength (1 micron) as that of the drive laser is subsequently injected into the plasma wake. The signal pulse is converted to a relativistic multi-millijoule near-single-cycle mid-IR pulse with a central wavelength of ~5 microns via frequency-downshifting, where the energy conversion efficiency is as high as approximately 30% when the drive and signal laser pulses are both at a few tens of millijoules at the beginning. Our scheme can be realized with terawatt-class kHz laser systems, which may bring new opportunities in high-field physics and ultrafast science

Dense GeV electron–positron pairs generated by lasers in near-critical-density plasmas

Pair production can be triggered by high intensity lasers via the Breit-Wheeler process. However, the straightforward laser-laser colliding for copious numbers of pair creation requires light intensities several orders of magnitude higher than possible with the ongoing laser facilities. Despite the numerous proposed approaches, creating high-energy-density pair plasmas in laboratories is still challenging. Here we present an all-optical scheme for overdense pair production by two counter-propagating lasers irradiating near-critical-density plasmas at only ~1022W cm-2. In this scheme, bright γ-rays are generated by radiation-trapped electrons oscillating in the laser fields. The dense γ-photons then collide with the focused counter-propagating lasers to initiate the multi-photon Breit-Wheeler process. Particle-in-cell simulations indicate that one may generate a high-yield (1.05×1011) overdense (4×1022 cm-3 ) GeV positron beam using 10 PW scale lasers. Such a bright pair source has many practical applications and could be basis for future compact high luminosity electron-positron colliders

Aqueous electrosynthesis of an electrochromic material based water-soluble EDOT-MeNH2 hydrochloride

2\u27-Aminomethyl-3,4-ethylenedioxythiophene (EDOT-MeNH2) showed unsatisfactory results when its polymerization occurred in organic solvent in our previous report. Therefore, a water-soluble EDOT derivative was designed by using hydrochloric modified EDOT-MeNH2 (EDOT-MeNH2·HCl) and electropolymerized in aqueous solution to form the corresponding polymer with excellent electrochromic properties. Moreover, the polymer was systematically explored, including electrochemical, optical properties and structure characterization. Cyclic voltammetry showed low oxidation potential of EDOT-MeNH2·HCl (0.85 V) in aqueous solution, leading to the facile electrodeposition of uniform the polymer film with outstanding electroactivity. Compared with poly(2′-aminomethyl- 3,4-ethylenedioxythiophene) (PEDOT-MeNH2), poly(2′-aminomethyl-3,4-ethylenedioxythiophene salt) (PEDOT-MeNH3 +A-) revealed higher efficiencies (156 cm2 C-1), lower bandgap (1.68 eV), and faster response time (1.4 s). Satisfactory results implied that salinization can not only change the polymerization system, but also adjust the optical absorption, thereby increase the electrochromic properties

Research on Hydraulic Safety Assessment of Water Distribution Systems

There are two key issues in the safety assessment of the water distribution system (WDS). One is how to evaluate the safety levels of water supply for customers, while the other is how to describe the importance of a pipe for the global or local WDS. The water demand guarantee rate (DGR) and the water demand failure rate (DFR) are proposed. The mathematical expectations of the DGR and DFR describe the average customer’s water safety levels for the first issue. Moreover, the unit influence of pipe failure (UIPF) is put forward for the second issue. It describes the importance of the pipe for the global or local system. Several cases show how to calculate the above values with the pressure-driven model. It is also shown how to find key pipelines in the WDS. The results show that the method can provide an effective reference for real-life WDS management. Document type: Articl

Interaction effects of pseudospin-based magnetic monopoles and kinks in a doped dipolar superlattice gas

Magnetic monopoles and kinks are topological excitations extensively investigated in quantum spin systems, but usually they are studied in different setups. We explore the conditions for the coexistence and the interaction effects of these quasiparticles in the pseudospin chain of the atomic dipolar superlattice gas. In this chain, the magnetic kink is the intrinsic quasiparticle, and the particle/hole defect takes over the role of the north/south magnetic monopole, exerting monopolar magnetic fields to neighboring spins. A confinement effect between the monopole and kink is revealed, which renormalizes the dispersion of the kink. The corresponding dynamical deconfinement process is observed and arises due to the kink-antikink annihilation. The rich interaction effects of the two quasiparticles could stimulate corresponding investigations in bulk spin systems

Generation of GeV positron and γ-photon beams with controllable angular momentum by intense lasers

Although several laser–plasma-based methods have been proposed for generating energetic electrons, positrons and γ-photons, manipulation of their microstructures is still challenging, and their angular momentum control has not yet been achieved. Here, we present and numerically demonstrate an all-optical scheme to generate bright GeV γ-photon and positron beams with controllable angular momentum by use of two counter-propagating circularly-polarized lasers in a near-critical-density plasma. The plasma acts as a 'switching medium', where the trapped electrons first obtain angular momentum from the drive laser pulse and then transfer it to the γ-photons via nonlinear Compton scattering. Further through the multiphoton Breit–Wheeler process, dense energetic positron beams are efficiently generated, whose angular momentum can be well controlled by laser–plasma interactions. This opens up a promising and feasible way to produce ultra-bright GeV γ-photons and positron beams with desirable angular momentum for a wide range of scientific research and applications

Single cycle terawatt twisted light pulses at midinfrared wavelengths above 10μm

Twisted light beams with orbital angular momentum provide an additional degree of freedom in controlling light-matter interactions, which are interesting for fundamental and applied research. Although there are various methods that can produce twisted laser beams at sub-micrometer or shorter wavelengths, it is still challenging to extend such beams to mid-infrared (mid-IR) wavelengths with relativistic intensity. Here, we present a promising scheme to generate such pulses converted through frequency downshift of intense driver optical pulses via a plasma-based photon decelerator. The resulting near-single-cycle vortex pulses cover a broad mid-IR spectral range up to 18 μm with energy conversion efficiency of 4.8% (energy ~150mJ) in the wavelength range above 7 μm. This long-wavelength infrared pulses at the terawatt level can be focused to relativistically high intensity, which may offer significant opportunities for high-field physics and ultrafast applications