Tetra-μ-benzoato-κ8 O:O′-bis­[(benzoic acid-κO)nickel(II)]

The title compound, [Ni2(C7H5O2)4(C7H6O2)2], is composed of two NiII ions, four bridging benzoate anions and two η1-benzoic acid mol­ecules. The [Ni2(PhCOO)4] unit adopts a typical paddle-wheel conformation. The center between the two NiII atoms represents a crystallographic center of inversion. In addition, each NiII ion also coordinates to one O atom from a benzoic acid mol­ecule. The crystal packing is realised by inter­molecular hydrogen-bonding inter­actions and π–π stacking inter­actions, with a centroid–centroid distance of 3.921 (1) Å

Bis­(2-methyl-1H-imidazole-κN 3)bis[2-(naphthalen-2-yl)acetato-κO]copper(II)

In the crystal structure of the title compound, [Cu(C12H9O2)2(C4H6N2)2], the Cu(II) cations are square-planar coordinated by two 1-naphthyl­acetate anions and two 2-methyl-imidazole ligands into discrete complexes that are located on centres of inversion. These complexes are linked into chains parallel to [010] by inter­molecular N—H⋯O hydrogen bonding between the N—H H atom of the 2-methyl-imidazole ligands and the carboxyl­ate O atoms that are not involved in metal coordination

Tensile behaviour of carbon fabric reinforced cementitious matrix composites as both strengthening and anode materials

Recently, a promising solution to corroded steel reinforced concrete structures was proposed in which a dual-functional carbon-fabric reinforced cementitious matrix (carbon-FRCM) composite is used for impressed current cathodic protection (ICCP) and structural strengthening (SS); this method is referred to as ICCP-SS. The tensile behaviour of carbon-FRCM must be understood for design purposes. In this study, the tensile characteristics of carbon-FRCM composites with different fabric reinforcement ratios were assessed to determine the strengthening capability of the materials. Then, using the composite as an anode material, the tensile behaviour of carbon-FRCM specimens subjected to anodic polarization in ICCP was evaluated. Direct tensile tests were conducted to obtain the tensile stress-strain behaviour of the carbon-FRCM specimens. By comparing the results from each case, the influences of different parameters on the tensile behaviour of the carbon-FRCM composites were evaluated, and useful information regarding the application of these materials in ICCP-SS was obtained

Bis(1-methyl-1H-imidazole-κN 3)bis­[2-(naphthalen-1-yl)acetato-κO]copper(II) monohydrate

In the crystal structure of the title compound, [Cu(C12H9O2)2(C4H6N2)2]·H2O, the CuII atom is coordinated by two 2-(naphthalen-1-yl)acetate anions and two 1-methyl­imidazole ligands, giving monomeric complexes with a square-planar coordination environment. Two complex mol­ecules and two water mol­ecules form a centrosymmetric ring system via O—H⋯O hydrogen bonds

Qualitative and quantitative analysis of catechin and quercetin in flavonoids extracted from Rosa roxburghii Tratt

Purpose: To perform a qualitative and quantitative analysis of catechin and quercetin in flavonoids extracted from Rosa roxburghii Tratt.Methods: Total flavonoids were determined using ultraviolet spectrophotometry (UV) at 500 nm. The optimal gradient program started with 15 % methanol and was kept within a period of 0 – 20 min, while 25 % methanol was kept within 20 – 33 min. Subsequently, the concentration of methanol was reduced to 15 % and was held for 10 min until the next injection. Mass spectrometry spray voltage was 4,000 V, ionization temperature 350 °C, atomizer pressure 35 psi, nitrogen flow rate 8 L/min, and mass scan range 200 – 800 m/z. The detection wavelength used for catechin and quercetin was 270 and 368 nm, respectively.Results: Based on the UV results, Rosa roxburghii Tratt content was 73.85 %, which is in agreement with the national standard. Liquid chromatography-mass spectrometry (LC-MS) results indicate that Rosa roxburghii Tratt flavonoids contained quercetin, 34.26 %, with relative standard deviation (RSD) of 2.88 % and catechin content of 2.97 % with RSD of 1.49 %.Conclusion: The proposed measurement method for determining the content of flavonoids in Rosa roxburghii Tratt has the advantage of simplicity, feasibility, good repeatability, and rapid and accurate analysis.Keywords: Rosa roxburghii Tratt, Flavonoids, Catechin, Querceti

Constraining Ultralight Dark Matter through an Accelerated Resonant Search

Experiments aimed at detecting ultralight dark matter typically rely on resonant effects, which are sensitive to the dark matter mass that matches the resonance frequency. In this study, we investigate the nucleon couplings of ultralight axion dark matter using a magnetometer operating in a nuclear magnetic resonance (NMR) mode. Our approach involves the use of a $^{21}$Ne spin-based sensor, which features the lowest nuclear magnetic moment among noble-gas spins. This configuration allows us to achieve an ultrahigh sensitivity of 0.73 fT/Hz$^{1/2}$ at around 5 Hz, corresponding to energy resolution of approximately 1.5$\times 10^{-23}\,\rm{eV/Hz^{1/2}}$. Our analysis reveals that under certain conditions it is beneficial to scan the frequency with steps significantly larger than the resonance width. The analytical results are in agreement with experimental data and the scan strategy is potentially applicable to other resonant searches. Further, our study establishes stringent constraints on axion-like particles (ALP) in the 4.5--15.5 Hz Compton-frequency range coupling to neutrons and protons, improving on prior work by several-fold. Within a band around 4.6--6.6 Hz and around 7.5 Hz, our laboratory findings surpass astrophysical limits derived from neutron-star cooling. Hence, we demonstrate an accelerated resonance search for ultralight dark matter, achieving an approximately 30-fold increase in scanning step while maintaining competitive sensitivity.Comment: 13 pages, 9 figure