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A concise and environmentally friendly protocol has been developed for the synthesis of cis-dihydrochromenones and trans-dihydrochromenones in EtOH at room temperature. Irradiation of 4-phenyl-3-arylcoumarins in EtOH with 313 nm UV light under an argon atmosphere at room temperature gave cis-4b,15c-dihydro-16H-benzofuro[3',2':7,8]phenanthro[9,10-c]chromen-16-ones and cis-8c,14b-dihydro-9H-benzo[11,12]chryseno[5,6-c]chromen-9-ones in good yields. And an analogous treatment of 4-phenyl-3-alkenylcoumarins as 4-phenyl-3-arylcoumarins provided trans-1,2,3,4,4a,14b-hexahydro-5H-phenanthro[9,10-c]chromen-5-ones. The described photorearrangement proceeded smoothly without the addition of any transition metals and additives. The photorearrangement of 4-phenyl-3-arylcoumarins is believed to proceed via 6π-electrocyclization, a [1,3]-hydrogen shift and keto-enol isomerization.

Violet phosphorene, a recently produced elemental 2D material, is a promising electronic and optoelectronic structure. The work function and band alignment of phosphorene nanoflakes are essential for their heterojunction structure design. The work function of violet phosphorene nanoflakes has been shown to decrease with the increase in layers from 5.16 eV to 4.79 eV and tends to be stable on a gold substrate, which has been confirmed via Kelvin probe force microscopy. The work functions measured on a silicon oxide substrate are much higher due to charge accumulation. The experimental work function of few-layer violet phosphorene is different from the intrinsic work function due to substrate doping, while that of thick violet phosphorene nanoflakes approaches the intrinsic work function value. Various functionals have been adopted for the work function calculation of few-layer violet phosphorene and the values obtained have been compared to the experimental results. The band alignments of different layered violet phosphorene materials calculated using the most accurate functional are demonstrated and compared to those of well-known materials to give a practical route for future applications. The work functions of the violet phosphorene nanoflakes have been shown to decrease due to oxidation, but they significantly improve after annealing in an argon atmosphere.

As a star of the MXene materials, 2D titanium carbide (Ti3C2Tx) has attracted broad interest from worldwide researchers in view of its potential application in energy storage, chemical sensing, electromagnetic interference shielding and flexible electronics. In order to further improve performances and satisfy the needs of emerging flexible applications, there is an urgent need to increase the electronic conductivity, environmental stability and flexibility of Ti3C2Tx film. Herein, a two-stage thermal treatment process in an argon atmosphere at low temperature (300 °C) is proposed to address this challenge. The resulting Ti3C2Tx film shows a 16-fold increase in electronic conductivity, while its environmental stability and flexibility are also greatly enhanced. Furthermore, systematic investigation into the microstructure and variations of Ti3C2Tx films before and after thermal treatment shed light on the underlying mechanism, which contributes to a deeper understanding of MXene properties and offers general guidance for improving the performance of MXene films.

A novel metal–organic-framework (MOF) composition-tuning strategy has been developed for the synthesis of well-defined hierarchical structures, which is based on reactivity modification of the zeolitic imidazolate framework (ZIF)-67. Typically, 1D ZIF-67@Ni-1,3,5-benzenetricarboxylic acid (ZIF-67@Ni-BTC) nanorods are obtained, which can be easily transformed into 1D graphene-coated NiCo2O4 (NiCo2O4@graphene) nanorods by an annealing treatment in an argon atmosphere, followed by oxidation in ambient air. By controlling the reaction time, novel structures such as hollow ZIF-67@Ni-BTC polyhedra and hollow ZIF-67@Ni-BTC polyhedra/ZIF-67@Ni-BTC nanorods can also be achieved. By virtue of the advantages of the structure and graphene coating, NiCo2O4@graphene nanorods as lithium storage materials exhibit high Li-storage capacity, excellent rate capability and remarkable cycling stability.

Domestic detergents are widely used and the detection of detergent residues on tableware is closely related to people's health. As is known to all, it is difficult to sample and measure the residual detergent on tableware. The purpose of this paper is to explore a rapid in situ detergent residues detection method. We have using laser-induced breakdown spectroscopy (LIBS) measured the detergent on porcelain plate. Based on our previous research, we further studied the spectra of detergent in argon atmosphere, and compared them with that in air. We found the spectral characteristics of the cyanogroup (CN) were related to the air around the measuring point. It was indicated that CN could not as previously speculated be used as the LIBS detection feature of detergent. The improvement of signal-to-noise ratio (SNR) in argon environment was proved and we made a study of semi quantitative measurement by the peak height of 330.30 nm in argon atmosphere. An experiment measuring the detergent on tableware after washed was taken. It illustrated that the LIBS technology has promising potential applications for tableware cleaning process or food production process as a means of on-line detection.

Ultrathin graphitic carbon nitride (g-C3N4) nanosheets were synthesized via thermal exfoliation of bulk urea-derived g-C3N4 under an argon atmosphere. As a visible-light responsive photocatalyst, this material exhibits a much superior photocatalytic activity in pollution degradation and H2 evolution than bulk g-C3N4, as a result of the extended region of visible light response and the enhanced surface area of ultrathin g-C3N4 nanosheets. These findings may provide a promising and facile approach to the design of high-performance photocatalysts.

In this work, N-doped graphene (NG) has been synthesized successfully by calcination of dicyandiamide and glucose mixture in an argon atmosphere. The photoluminescence properties of NG were studied systematically. The results show that N-doping can quench its fluorescence and the quenching efficiency depends on the graphitic N content.

Photocatalytic reduction of 25 μmol 2,2'-dinitrobiphenyl in 50% aqueous iso-propanol and 50 mg P25-TiO2 under an argon atmosphere and 20 h UV light irradiation selectively produced 23.8 μmol of benzo[c]cinnoline (95%), and 2,2'-biphenyldiamine (5%) whose amount gradually increased with the irradiation time beyond 20-24 h due to further reduction of benzo[c]cinnoline.

A novel ether/BF3 reductive system has been described, in which diphenylmethanols and their ether and ester derivatives are used as starting materials. Reductions are performed in ether under reflux and an argon atmosphere, and the addition of extra water is beneficial to this reduction. A series of alkanes are able to be prepared with good to excellent yields. A deuterated experiment exhibits that the reductive hydrogen is generated from ether. The mechanism is discussed in detail to explain the observed reactivity.

Single crystals of multifunctional Ca0.9Nd0.1Ti0.9Al0.1O3 have been grown in air and also in argon atmosphere using an optical floating zone technique. The phase composition of the grown single crystals was verified by a powder X-ray diffraction technique. The quality of the grown single crystals was ascertained by rocking curves and Laue patterns. Raman spectra showed the disordering in the B cation site due to the valence mismatch between Ti4+ and Al3+. The energy levels of Nd3+ in the CaTiO3 matrix were determined using the absorption and emission spectra. An absorption band at 806 nm and a strong emission band at 1064.48 nm show that the crystals have good laser optical quality for diode-laser pumping.

The electrochemical reduction of aromatic aldehydes (ArCHO) such as 2-naphthaldehyde (1), 4-dimethylaminobenzaldehyde (2), 3-methoxybenzaldehyde (3) and 2-pyrrole carboxaldehyde (4) in N,N-dimethylformamide with tetrabutylammonium hexafluorophosphate as supporting electrolyte, under an argon atmosphere and in the presence of protons donors (AH2) such as fluorene (FlH2) or indene (InH2), gives products such as (ArCH2A) and/or [ArCH(AH)2] (AH=FlH or InH). Three consecutive chain reactions are initiated by proton abstraction from fluorene or indene by a base electrogenerated by the reduction of ArCHO. The propagation steps of the first chain reaction involves addition of AH- to ArCHO and protonation of the resulting alcoholate with regeneration of AH- to give the carbinol ArCH(OH)AH. The second chain reaction is the base-catalyzed dehydration of ArCH(OH)AH to ArCH2A. The third is the addition of AH- to ArCH2A, giving ArCH(AH)2 with regeneration of AH-. Re′actions en chaine induites e′lectrochimiquement. Re′actions d'alde′hydes aromatiques induites par des bases e′lectroge′ne′re′es. La re′duction e′lectrochimique d'alde′hydes aromatiques (ArCHO) tels que le 2-naphtalde′hydes (1), le 4-dime′thylaminobenzalde′hyde (2), le 3-me′thoxybenzalde′hyde (3) et le 2-pyrrolecarboxaldehyde (4) en pre′sence d'hexafluorophosphate de te′trabutylammonium comme e′lectrolyte support sous l'influence de donneurs de protons AH2 tels que le fluorene (FlH2) ou l'indene (InH2) conduit aux compose′s ArCH2A et (ou) ArCH(AH)2 (AH=FlH ou InH). Trois re′actions en chaine conse′cutives sont initie′es par abstraction d'un proton de AH2 par la base e′lectroge′ne′re′e par re′duction de ArCHO. L'e′tape de propagation de la premiere re′action en chaine correspond a l'addition de l'anion AH- sur l'alde′hyde ArCHO suivie de la protonation de l'alcoolate re′sultant par AH2 pour conduire a l'alcool ArCH(OH)AH avec re′ge′ne′ration de AH-. La seconde re′action en chaine correspond a la de′shydratation de ArCH(OH)AH en ArCH2A sous l'influence de la base AH-; enfin la formation de ArCH(AH)2 s'effectue par addition de AH- sur ArCH2A suivie d'une protonation par AH2.

Superconducting YBa2Cu3O7 –x films have been synthesized successfully at a low temperature of 600 °C by the solution process using the Y–Ba–Cu heterometallic alkoxide. The heterometallic alkoxide was synthesized by chemical modification and partial hydrolysis of component alkoxides. In gel films prepared from a heterometallic alkoxide solution, YBa2Cu3O7 –x was obtained as a single phase at 600 °C under an argon atmosphere, whereas YBa2Cu3O7 –x together with other crystalline phases was obtained from mixed alkoxide solutions. The heterometallic alkoxide precursor and the firing process under argon both proved effective for the low-temperature synthesis of single-phase YBa2Cu3O7 –x films. The film fired at 800 °C for 6 h under argon followed by annealing at 450 °C for 24 h under oxygen, showed zero resistance at 74 K.

Solvent-free [LiCH2SMe]infinity forms a layer structure consisting of four- (Li2C2), five- (Li2CS2), and six-membered (Li2C2S2) rings in the solid state; the compound violently explodes upon heating to T=160+/-5 degrees C under an argon atmosphere.

Silica gel-phenolic resin hybrid fibres have been synthesized by hydrolysis and polycondensation of tetraethoxysilane [Si(OC2H5)4, TEOS] in the presence of phenolic resins in ethanol under acidic conditions. The fibres had C : Si atomic ratios of 2.6–5.4 and could be converted into β-silicon carbide (SiC) fibres by carbothermal reduction at 1500 °C under an argon atmosphere.

Using BCHPC as a source of alkoxycarbonyloxyl radical at moderate temperature in benzene or cyclohexane and in the absence of O2(under argon), the peroxydecanoic acid RCO3H is transformed into nonan-1-ol ROH in good yield. A mechanism, implying the acylperoxyl radical RCO3˙ as an intermediate, is proposed.

A prerequisite for the direct spectrographic analysis of molten steels in industrial furnaces is the knowledge that good quality spectra can be obtained from molten steel surfaces, and that precise quantitative determinations can be made by using such spectra.The emission-spectrographic determination of nickel from a molten steel surface at 1600° C under an argon atmosphere has, therefore, been investigated. When a condensed spark between a graphite electrode and the molten steel surface was used, spectra of good quality were produced. The standard deviations in the error for the determination of 0·7 to 1·8 per cent. of nickel in molten and solid steel samples, analysed under similar conditions, were 0·045 and 0·022 per cent., respectively.

The final product from controlled-potential reduction of aqueous solutions of trans-[Rh(en)2Cl2]+(where en = ethylenediamine), under an argon atmosphere, has been shown to be trans-[Rh(en)2H(OH)]+. The pseudo-acid–base equilibrium (i) is shown to operate in solutions which are strongly alkaline (pH > 12). In the absence of RhIII–H + OH–⇌ RhI+ H2O (i), oxygen, aqueous solutions of trans-[Rh(en)2H(OH)]+ are stable toward both acid and base (0 < pH < 12) at room temperature : in the presence of oxygen, no reaction is observed in acidic solutions whereas rapid reactions are observed in basic solutions, giving initially the hydroperoxorhodium(III) complex [Rh(en)2(OH)(OOH)]+, which on concentration yields the blue superoxo-bridged rhodium(III) dimer [(H2O)(en)2RhO2Rh(en)2(H2O)]5+. Mechanisms of these reactions are discussed.