Radical metallacyclopropene: synthesis, structure and aromaticity.

Metallaaromatics are an important class of aromatic compounds, showing diverse and interesting aromatic properties. Radical rhenabenzofurans 1-3 with a fused metallacyclopropene unit are reported, containing d1 Re centers. Computational studies show that the three-membered rhenacyclopropene ring is σ-aromatic, while the rhenafuran ring is nonaromatic. These complexes represent the first radical metallacyclopropenes. α-Metallabenzofuran complexes 4-5 with d0 Re centers and 6 with a d2 Re center are also synthesized. α-Metallabenzofurans 1-6 have adjacent oxidation states (Re(III), Re(IV), and Re(V)). Both the structure and aromatic nature of these metallacycles are affected by the change of oxidation states of the metal center.

Inorganic phosphate regulated high luminescence NaYF4:Yb3+, Er3+ as an iron ion fluorescent nanoprobe.

The iron ion in industrial circulating cooling water is an important indicator for early warning of equipment corrosion and control level. It is interesting to construct an upconversion luminescence iron ion nanoprobe with a common inorganic phosphate water treatment agent. Herein, inorganic phosphate sodium hexametaphosphate (SHMP) was used to regulate the morphology and functionalization of NaYF4:Yb3+, Er3+ upconversion luminescent nanoprobe (UCNPs) and applied to fluorometric detection of trace Fe(III) in water based on the fluorescence quenching which is caused by the selective coordination between hexametaphosphate on the surface of UCNPs and Fe(III). The structure, morphology, and luminous intensity of UCNPs were regulated by disodium hydrogen phosphate (ADSP), sodium tripolyphosphate (STPP) and sodium hexametaphosphate(SHMP). The UCNPs functionalized with SHMP has high sensitivity and selectivity for Fe(III) detection. The linear range and detection limit are 1.0-50 µM and 0.2 µM, respectively. The method has satisfactory results for the detection of trace Fe(III) in industrial circulating cooling water.

α-Rhenabenzofuran with nonaromatic T0 and aromatic S1 states.

The first α-rhenabenzofuran complexes 2-5 are obtained from one-pot reactions of ReCl3(PMePh2)3 with o-ethynyl phenols. With a delocalized structure, these paramagnetic compounds are nonaromatic at the ground state, which is a triplet. But they exhibit an aromatic singlet excited state, revealed by DFT studies.

Three-dimensional gold nanowires with high specific surface area for simultaneous detection of heavy metal ions.

Traditional detection methods to detect heavy metal ions are time-consuming, complicated, and expensive. Here, we developed a simple electroless plating method to prepare three-dimensional gold nanowire (Au NW) films with high specific surface area. In an aqueous plating bath, tetrachloroauric acid, 4-dimethylaminopyridine and formaldehyde are used as precursor, ligand, and reducing agent, respectively. An electrochemical sensor based on a Au NWs/SPE could be applied for simultaneous detection of lead (Pb(II)), arsenic (As(III)), and mercury (Hg(II)) ions. The detection limits of Pb(II), As(III), and Hg(II) are 2.6, 1.5, and 4.2 µg L-1, all lower than the permissible limits of the WHO for drinking water (the permissible level of Pb(II) and As(III) is 10.0 µg L-1, and the permissible level of Hg(II) is 6.0 µg L-1), respectively. This work presents a simple and novel method to prepare gold nanowires for quick detection of trace heavy metal ions.

Note: Erosion of W-Ni-Fe and W-Cu alloy electrodes in repetitive spark gaps.

A pair of W-Ni-Fe and W-Cu electrodes were tested under 100 kA level pulsed currents for 10 000 shots, respectively. Surface roughness and morphology characteristics of the two pairs of electrodes were obtained and compared. Experimental results indicated cracks divided the W-Cu electrode surface to polygons while the W-Ni-Fe electrode surface remained as a whole with pits and protrusions. Accordingly, the surface roughness of W-Ni-Fe electrodes increased to ∼3 µm while that of W-Cu electrodes reached ∼7 µm at the end of the test. The results reveal that the W-Ni-Fe alloy has a better erosion resistance and potential to be further applied in spark gaps.

[System of ns time-resolved spectroscopy diagnosis and radioprotection].

Cathode plasma of high current electron beam diode is an important research on high power microwave and strong pulsed radio accelerator. It is a reliable method to study cathode plasma by diagnosing the cathode plasma parameters with non-contact spectroscopy measurement system. The present paper introduced the work principle, system composition and performance of the nanosecond (ns) time-resolved spectroscopy diagnosis system. Furthermore, it introduced the implementing method and the temporal relation of lower jitter synchronous trigger system. Simultaneously, the authors designed electromagnetic and radio shield room to protect the diagnosis system due to the high electromagnetic and high X-ray and γ-ray radiation, which seriously interferes with the system. Time-resolved spectroscopy experiment on brass (H62) cathode shows that, the element and matter composition of cathode plasma is clearly increase with the increase in the diode pulsed voltage and current magnitude. The spectroscopy diagnosis system could be of up to 10 ns time resolve capability. It's least is 2 ns. Synchronous trigger system's jitter is less than 4 ns. The spectroscopy diagnosis system will open a new way to study the cathode emission mechanism in depth.

A 800 kV compact peaking capacitor for nanosecond generator.

An extremely compact high voltage peaking capacitor is developed. The capacitor has a pancake structure with a diameter of 315 mm, a thickness of 59 mm, and a mass of 6.1 kg. The novel structural design endows the capacitor with a better mechanical stability and reliability under hundreds of kilovolts pulse voltage and an inner gas pressure of more than 1.5 MPa. The theoretical value of the capacitor self-inductance is near to 17 nH. Proved by series of electrical experiments, the capacitor can endure a high-voltage pulse with a rise time of about 20 ns, a half-width duration of around 25 ns, and an amplitude of up to 800 kV in a single shot model. When the capacitor was used in an electromagnetic pulse simulator as a peaking capacitor, the rise time of the voltage pulse can be reduced from 20 ns to less than 3 ns. The practical value of the capacitor's inductance deduced from the experimental date is no more than 25 nH.

[New processing procedure for Croton tiglium with study on comparison of Croton tiglium and processed product].

OBJECTIVE: To build a new processing procedure for Croton tiglium, providing a more simple, efficient and safe way of processing. METHODS: Used the contents of isoguanosine and toxic protein in Croton tiglium as the indexes to investigate the effect of different temperature, thickness and baked time on processing for Croton tiglium. After established all factors and levels, processed a batch of Croton tiglium under optimum processing conditions and compared it with raw Croton tiglium in the test of acute toxicity and gastrointestinal propulsive motility. RESULTS: The parameters of optimum processing were as follows:the temperature was set at 180 degrees C, the thickness of placement was 3 cm and baked time was 90 min. The LD50 value of raw Croton tiglium and the processed Croton tiglium was 888 mg/kg and 2139 mg/kg respectively. CONCLUSION: The processing procedure is simple, affordable, safe and efficient, deserved to promote for application.