Discontinuous atmospheric pressure interface (DAPI), consisting of a pinch valve, a silicone tube, and two metal capillaries, is a common inlet for miniature ion trap mass spectrometers (ITMS). It can improve the transport efficiency while help the miniaturization of the mass spectrometers.
　　DAPI-ITMS is widely used for drug detection, metabolomics analysis and environmental applications.
　　Recently, a research group led by Prof. LI Haiyang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) discovered a new ionization phenomenon known as triboionization inside the silicone tube of the DAPI. In the phenomenon, analytes could still be detected with no extra ionization source in a DAPI-ITMS.
　　This study was published in Analytical Chemistry on November 24.
　　The schematic diagram of DAPI and mass spectra of mixture as a function of humidity (Image by XU Chuting and RUAN Huiwen)
　　The researchers confirmed that the friction on the inner surface of silicone tube could induce ionization during the opening of the DAPI. And they improved the ionization efficiency of DAPI-ITMS by changing the material and roughness of inner surface of the silicone tube in the DAPI.
　　Moreover, they found that by increasing the number and the frequency during the on/off of the pinch valve of the DAPI, the signal intensity of ITMS could be improved by nearly 20 times.
　　"We have applied this triboionization to detect the ketones on the inner wall of silicone tube after continuous enrichment," said Prof. LI. "This work proposed an ionization source which needs no light, heat, radiation, and electric supply."
　　The above work was supported by Innovation Foundation of DICP and Natural Science Foundation of Liaoning Province. (Text by XU Chuting and RUAN Huiwen)

　　Nitrosobenzene (PhNO) is implicated in a range of chemical transformations. A plethora of transition metal complexes can activate PhNO in various coordination modes, and electron-rich low-valent metal centers can induce reduction of PhNO.
　　However, the functionalization of PhNO through the synergistic interaction of metal and ligand is still unclear.
　　Recently, Prof. YE Shengfa's group from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. QU Jingping's group from Dalian University of Technology, achieved facile conversion of nitrosobenzene to aniline under ambient conditions by a thiolate-bridged diiron complex.
　　This study was published in Journal of the American Chemical Society on Oct. 7.
　　By using X-ray single crystal diffraction, 57Fe Mössbauer nuclear magnetic resonance, and infrared spectroscopies coupled with density functional theory calculations, the researchers presented an unprecedented activation pathway of PhNO induced by a thiolate-bridged diiron complex.
　　Such a transformation realizes concerted yet asynchronous four-electron reduction of PhNO to selectively furnish benzenesulfinamide, for which the four electrons all came from the bridging thiolate ligand, whereas the iron center only served as an electron shuttle. The resulting sulfinamide ligand has a greater propensity to undergo further reduction to release aniline compared with PhNO.
　　"The formation of sulfinamide accelerates degradation of PhNO to aniline, which helps to understand the metabolism of PhNO in biological systems," said Prof. YE. (Text by JIANG Yang)

　　A telomere is a region of repetitive nucleotide sequences associated with specialized proteins located at the ends of linear eukaryotic chromosomes to protect the chromosomes from progressive degradation and ensure its integrity.
　　During cell division, telomeres will shorten gradually in human somatic cells, which limits the number of times they can divide. Therefore, telomeres are considered to be closely related to cell aging. Telomerase will be activated during cell division to synthesize telomere DNA for compensating the loss of telomeres.
　　Recently, a research group led by Prof. LI Guohui from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. LEI Ming's and Prof. WU Jian's group from Shanghai Jiao Tong University School of Medicine, have revealed the key molecular mechanisms of how telomerase repeatedly uses its RNA template to synthesize telomeric DNA.
　　This study was published in Cell Research on Nov. 15.
　　Overall structure of human telomerase holoenzyme in complex with the ssDNA substrate (top left); structure of the catalytic core of human telomerase and schematic diagram of the primer–template duplex in the structure in which the zipper head Leu980 (light green circle) destabilizes and disrupts the canonical W-C hydrogen pairing at positions 5 and positions 6 and 7 (top right); A schematic model for telomerase catalytic cycle of repeat synthesis (bottom) (Image by ZHANG Yuebing and LI Guohui) 
　　Previous studies found that canonical reverse transcriptase (RT) requires a primer-template duplex of at least six base pairs to initiate DNA synthesis, while human telomerase only needs a three-base-paired primer-template duplex to sustain its catalytic activity. The mechanism of the above phenomenon is still unclear.
　　The research group from Shanghai Jiao Tong University School of Medicine identified the cryo-EM structure of human telomerase holoenzyme with bound telomeric DNA at resolutions of 3.54 Å and 3.94 Å for the catalytic core and the biogenesis module, respectively.
　　Based on these structural information and theoretical studies conducted by Prof LI Guohui's group, this study indicated that the key amino acid Leu980 in the catalytic subunit of human telomerase played a key role in controlling the length and pairing of the DNA-RNA hybrid double helix. The researchers found that Leu980 acted like a zipper head, which separated the substrate and only maintained the three-base-paired primer–template duplex.
　　Theoretical studies showed that mutation of Leu980 to Gly restored a tighter six-base pair conformation of the DNA-RNA hybrid double. Subsequent biochemical experiments confirmed that the Leu980Gly mutation would affect the continuous and stable DNA synthesis ability of human telomerase.
　　This work provides novel insights for an in-depth understanding of the telomere repeat synthesis. It was supported by the National Natural Science Foundation of China and the National Key R&D Program of China. (Text by ZHANG Yuebin and LI Guohui)

Surface charges play an important role in the catalytic reaction in photoelectrochemistry. However, the spatial heterogeneities of charge transfer sites and catalytic sites at the electrode/electrolyte interface obscures the surface reaction process.Recently, a research group led by Prof. LI Can and Prof. FAN Fengtao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) and their collaborators revealed the linear law between surface charge density and reaction current in photoelectrocatalysis.This study was published in The Journal of Physical Chemistry Letters on Nov. 2.Local HER current on Pt/Ti islands was strictly regulated by the surface charge density in a linear fashion (Imaged by NIE Wei and FAN Fengtao)The researchers quantified the relationship between the local catalytic current of the hydrogen evolution reaction (HER) and the surface charge density using operando spatially resolved photovoltage microscopy on the Pt/Ti array on the p-Si photoelectrode.They found that the local HER current could be linearly regulated by the charge density at reactive sites by concurrently adjusting the bias potential and the spacings of the Pt/Ti islands."Distinguishing from the electrocatalytic process in which the applied voltage changes activation free energy, the uniqueness of applied potential on the photoelectrode was found to determine the charge density of photogenerated minorities and hence the reaction current," said Prof. FAN.This work was supported by the Fundamental Research Center of Artificial Photosynthesis, the National Natural Science Foundation of China, and CAS Projects for Young Scientists in Basic research and Interdisciplinary Innovation Team. (Text by NIE Wei and FAN Fengtao)

The involvement between electron transfer (ET) and catalytic reaction at electrocatalyst surface makes electrochemical process challenging to understand and control. How to experimentally determine ET process occurring at nanoscale is important to understand the overall electrochemical reaction process at active sites.Recently, a research group led by Prof. LI Can and Prof. FAN Fengtao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) captured the electron transfer imaging in electrocatalysis process.This study was published in Nano Letters on Oct. 14.Electron transfer current followed the trend: corner> edge> basal plane, driven by the interfacial inner potential differences (Imaged by NIE Wei and FAN Fengtao)The researchers established an in-situ electrochemical imaging method with nanoscale spatial resolution, which combined atomic force microscopy and scanning electrochemical imaging. This method can realize the three-dimensional movement of the scanning nanoprobe to map the local distribution of the generated outer-spherical electron transfer molecules and the catalytic product molecules.The visual electron transfer images on metal nanoplates directly demonstrated that the electron transfer process at nanoscale presented a site-dependent heterogeneity.Moreover, to decouple the interference of the mass transfer effect on the electron transfer, the researchers conducted a series of elaborate experiments and complex mathematical modeling to extract the rate constant and internal potential difference. They found that the relationship between the interfacial inner potential difference and the rate constant followed a linear fashion.This work realizes the in-situ observation of electron transfer process and catalytic reaction in the electrochemical reaction, and provides new ideas for the development of in-situ imaging characterization method and the detection of the mechanism of the electrocatalytic reactions."This is a new milestone of the scanning electrochemical probe techniques, making it possible to discover the structure-performance relation of nanocatalyst from the bottom of physical and chemical principles," commented by one of the reviewers. (Text by NIE Wei and FAN Fengtao)

　　A research team led by Prof. CHEN Qing-An from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) realized photo-induced catalytic halopyridylation of alkenes using halopyridines and non-activated olefins as simple reaction substrates.
　　Their findings were published in Nature Communications on Nov. 11.
　　Cross-coupling of aryl halides with alkenes (Image by GUO Shiyu)
　　The researchers added trifluoroacetic acid to promote the protonation of halopyridines, after which the iridium photocatalyst was more likely to undergo oxidative quenching pathway, and the protonated halopyridines was excited to generate electrophilic pyridyl radicals.
　　Therefore, the pyridyl radicals could further undergo radical addition with electron-rich non-activated olefins to generate alkyl radical intermediates.
　　They also found that the iridium photocatalyst in the oxidation state could oxidize the generated alkyl radical to carbocations, and further capture the halide ions in the system to construct new C-C and C-X bonds (X=Cl, Br, I).
　　This study was supported by the National Natural Science Foundation of China and Liaoning Province Doctoral Research Startup Fund Project. (Text by GUO Shiyu)