Interfacial Electro-Epoxidation in Electrospray Ionization Mass Spectrometry for Simultaneous Analysis of Negatively and Positively Charged Unsaturated Glycerophospholipids

In this study, we developed an AC-induced interfacial electro-epoxidation reaction for localization of double-bonds in nega-tively and positively charged forms of lipids simultaneously. An AC voltage plays multiple roles in this method, including initiation of the electrochemical epoxidation of double-bonds in both charge states of lipids, and protonation and deprotona-tion of lipid for detection in both ion modes. The advantages of simultaneous detection of negatively changed and positively charged unsaturated lipids, voltage-controlled electrochemical derivatization, and the low sample consumption allow its wide applications in a broad range of lipid-related research

Accelerated Two-Phase Oxidation in Microdroplets Assisted by Light and Heat without the Use of Phase-Transfer Catalysts

Two-phase oxidation of alcohols to corresponding aldehydes could be achieved without any phase-transfer catalyst in microdroplets. Herein, we realized reaction acceleration for two-phase oxidation in microdroplets using diluted oxidants under light and thermal irradiation. Lights of short wavelengths were more desirable to reaction acceleration than lights of long wavelengths. However, yields were dramatically improved by moderate heating but reversely decreased by excess heat owing to crystallization. The yields with 5-fold diluted NaOCl solution under light and thermal irradiation were comparable to those with undiluted NaOCl in the absence of light and heat. The dilution of NaOCl not only improved robustness of the sprayer (no salt deposition at the capillary tip) but also met the requirements of green chemistry

Two New Devices for Identifying Electrochemical Reaction Intermediates with Desorption Electrospray Ionization Mass Spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) previously has been used to capture and identify transient intermediates in electrochemical redox reactions on a platinum-covered rotating waterwheel. We present here two different setups that use a flat surface with porous carbon tape as the working electrode, where analyte-containing microdroplets from the DESI probe contacted with electrolyte supplied onto the surface. One setup had the conducting carbon tape in the form of a grooved inclined plane; the other one was in the form of a flat plane that had the conducting carbon tape as its front surface. Both these setups, which were relatively robust and easy to operate, overcame interference from the electrospray sheath gas that disturbs and dries the flowing electrolyte. By using the inclined-plane device, we observed radical cations and dimer species generated in the electrochemical oxidation of triphenylamine, diimine and imine alcohol in the electrochemical oxidation of uric acid, and the reductive cleavage of disulfide bonds in glutathione disulfide. By using the device with the flat carbon tape, we detected nitrenium ions generated in the electrochemical oxidation of <i>N</i>,<i>N</i>′-dimethyoxydiphenylamine and di-<i>p</i>-tolylamine. Our experience suggests that the flat porous carbon tape surface might be preferable over the inclined plane because of its ease of setup

Effect of the δ Phase on the Tensile Properties of a Nickel-Based Superalloy

Nickel-based superalloys are widely used in aerospace and other fields due to their excellent properties. In this study, the aging treatment and tensile tests of a GH4169 alloy were carried out. The effects of the &delta; phase on the alloy&rsquo;s mechanical properties and fracture behavior were studied. The results showed that the appearance of the &delta; phase changed from a short rod shape to a needle shape with an increase in aging time. The precipitation method changed from a single mode of precipitation along the grain boundary to two modes of precipitation along the grain boundary and direct precipitation inside the grain. The yield strength and ultimate tensile strength of the alloy first increased and then decreased with an increase in aging time and were related with the microstructure of the &delta; phase. The similar Widmanstatten structure was not conducive to the mechanical properties of the alloy. The distribution of the &delta; phase led to the generation of inhomogeneous strain and limited the surface roughening during plastic deformation. The voids initiated at the interface between the &delta; phase and the matrix &gamma; phase or directly from the &delta; phase fracture site

Construction of g-C3N4-mNb2O5 Composites with Enhanced Visible Light Photocatalytic Activity

A series of composites consisting of g-C3N4 sheet and mesoporous Nb2O5 (mNb2O5) microsphere were fabricated by in situ hydrolysis deposition of NbCl5 onto g-C3N4 sheet followed by solvothermal treatment. The samples were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of the composites was studied by degradation of rhodamine B (RhB) and tetracycline hydrochloride (TC-HCl) in aqueous solution under visible light irradiation (&lambda; &gt; 420 nm). Compared with g-C3N4 and mNb2O5, g-C3N4-mNb2O5 composites have higher photocatalytic activity due to synergistic effect between g-C3N4 and mNb2O5. Among these composites, 4% g-C3N4-mNb2O5 has the highest efficiency and good recyclability for degradation of both RhB and TC-HCl

Water Microdroplet Chemistry for Accelerating Green Thiocyanation and Discovering Water-Controlled Divergence

As an important class of five-membered N-heterocyclic compounds, pyrazolin-5-one derivatives play an extremely important role in the construction of fine chemicals and bioactive molecules. Traditional synthetic methods for functionalization (i.e., thiocyanation) used organic solvents to undergo slow reactions, which poses problems such as environmental pollution, low efficiency, and high cost. Herein, we develop a green, efficient, and gram-scale pyrazolinone thiocyanation method by water microdroplet chemistry. Using water as the solvent, this microdroplet method reduced the equivalent of oxidant and completed the thiocyanation reaction (>90% yields) within milliseconds (reaction time for a single microdroplet, although the actual collection time for detectable amounts of products is on the order of minutes to hours). The water microdroplet method was suitable for various pyrazolinone derivatives, and the yields of the aqueous microdroplet reactions were much higher than those of bulk reactions. In addition, we efficiently discovered a unique role of water in driving different reaction pathways by aqueous microdroplet chemistry. In the presence of water, pyrazolinone incubated with ammonium thiocyanate afforded tandem thiocyanation/ammonium cross-coupling products, compared to only thiocyanated products in pure organic solvents, leading to a possible water-controlled divergence

Electronic supplementary material from Cerium promoted V-g-C₃N₄ as highly efficient heterogeneous catalysts for the direct benzene hydroxylation

Cerium promoted V-g-C3N4 as highly efficient heterogeneous catalysts for the direct benzene hydroxylatio

Microdroplet-Controlled Divergent Reactivity at a Gas-Organic Interface

Gas-liquid Interface plays key roles in many fantastic phenomena due to specific properties. Although remarkable reactivities were benefited from gas-water interface of aqueous microdroplets, it remains unknown for gas-organic interface. This work discovers such extraordinary reactivity of gas-organic interface using organic microdroplets (acetonitrile and other organic solvents). This reactivity at the gas-organic interface facilitated a novel micrordroplet-controlled divergence, i.e., double C–N cleavage in high efficiency (yields > 90% in milliseconds) compared to single C–N bond breakdown and intramolecular cycloarrangement in bulk under harsher conditions from the same imidazolines. This study is not only important to wide applicability and inherent mechanisms of the gas-organic interface but also enables good insights into gas-water and other interface-rich studies in atmospheric and photochemistry, on-water chemistry, biological and biomedical, industrial, and energy