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The reactions of the iridium dimer anion [Ir

The structure of the [Rh2C3]+ ion and its reaction with CH4 in the gas phase have been studied by infrared photodissociation spectroscopy and mass spectrometry in conjunction with quantum chemical calculations. The [Rh2C3]+ ion is characterized to have an unsymmetrical linear [Rh-C-C-C-Rh]+ structure existing in two nearly isoenergetic spin states. The [Rh2C3]+ ion reacts with CH4 at room temperature to form [Rh2C]+ + C3H4 and [Rh2C2H2]+ + C2H2 as the major products. In addition to the [Rh2C]+ ion, the [Rh2 13C]+ ion is formed at about one-half of the [Rh2C]+ intensity when the isotopic-labeled 13CH4 sample is used. The production of [Rh2 13C]+ indicates that the linear C3 moiety of [Rh2C3]+ can be replaced by the bare carbon atom of methane with all four C-H bonds being activated. The calculations suggest that the overall reactions are thermodynamically exothermic, and that the two Rh centers are the reactive sites for C-H bond activation and hydrogen atom transfer reactions.

Microplastic (MP) pollution is one of the greatest threats to marine ecosystems. The deep sea is regarded as a hotspot for MP accumulation, but how do deposited MPs evolve from a long-term perspective? In particular, the occurrence features of MPs in cold seeps, which are characterized by methane-rich fluid seepage fueling one of the richest ecosystems on the seafloor, are unclear. Here, we demonstrated how MPs have been deposited in the Haima cold seep since the invention of plastics. We found that the burial rate of MPs exponentially increased since the massive global use of plastics in the 1930s, and this cold seep accommodates more MPs than do coastal areas. Upwelling fluid seepage facilitated the fragmentation and degradation behaviors of MPs. More MP-degrading microorganism populations and functional genes were discovered in methane seepage areas. Our findings illuminated the need to determine fundamental strategies for sustainable marine plastic pollution mitigation in the natural deep-sea environment.

The activation and coupling reactions of methane and acetylene mediated by M+ (M = Os, Ir, Pt, and Au) have been comparatively studied at room temperature by the techniques of mass spectrometry in conjunction with theoretical calculations. Studies have shown that Os+ and Ir+ can mediate the activation/coupling reaction of CH4 and C2H2, while Pt+ and Au+ cannot, which could be explained by the number of empty valence orbitals in the metal atom. In addition, there are different competition channels for the reaction mediated by Os+ and Ir+: an expected dehydrogenation and an unexpected C/C exchange. We find that if the rare C/C exchange reaction takes place, there are symmetric carbon atoms in the reaction intermediate and the C/C exchange reaction is favored kinetically. The C/C exchange reaction must be considered, which will affect the yield of the products in the primary reaction. This study shows the molecular-level mechanisms which include the C/C exchange reaction in the activation and coupling reaction of organic compounds mediated by different metals.

The reactions of iridium- and osmium-carbyne hydride cations [HIrCH]+ and [HOsCH]+ with ethylene have been studied using mass spectrometry with isotopic-labeling in the gas phase. The carbyne react...

The carbon chain cations HnC4O+ (n = 1, 2) were generated via pulsed laser vaporisation of a graphite target in supersonic expansions of helium seeded with carbon monoxide and acetylene. The infrared spectra were measured via mass-selected infrared photodissociation spectroscopy of their CO-tagged complexes [HnC4O·CO]+ (n = 1, 2). Their geometric and electronic structures were determined by gas-phase infrared photodissociation spectra combined with theoretical calculations. The results show that the HnC4O+ (n = 1, 2) core cations are linear carbon chain derivatives which are terminated with hydrogen/dihydrogen and oxygen atoms. The HC4O+ cation has 3Σ− electronic ground state with cumulene-like carbon chain structure, while H2C4O+ cation has 2B1 electronic ground state with polyyne-like carbon chain structure. The CH and CH2 terminal groups have different influence on the type of carbon-carbon bonds in the carbon chain derivatives, due to the sp and sp2 hybridisation property. The carbon chain cations HnC4O+ (n = 1, 2) are studied by gas-phase infrared photodissociation spectra of CO-tagged complexes [HnC4O·CO]+ (n = 1, 2) combined with theoretical calculations. Studies show that the structures of the HnC4O+ (n = 1, 2) core cations are linear carbon chain derivatives which are terminated with hydrogen/dihydrogen and oxygen atoms. The spectrum of [HC4O·CO]+ shows two bands above 3000 cm−1, suggesting possible isomers.

Objective: The purpose of the research is to study the sEMG characteristics of associated major muscle groups (agonist muscles) in three-step leap over stumps of 400m obstacle and the relationship between them and muscle performance. Methods: This research tests and analyzes the original electromyography, iEMG and iEMG% of seven male cadets who did quite well in 400m obstacle test by using the surface electromyography telemetry and anatomical analysis of the action, combining with sEMG synchronal video collecting data analysis. Results: The order of muscle power that functions in the right lower limb muscle groups and rectus abdominis is the following: tibialis anterior muscle and quadriceps generate power first, followed by rectus abdominis muscles, gastrocnemius, hamstrings, and gluteus maximus in sequence. The iEMG and iEMG% order from large to small is: gastrocnemius, tibialis anterior, quadriceps, hamstrings, rectus abdominis muscle, and gluteus maximus. Conclusion: The completion of three-step leap over stumps mainly depends on the muscle power of lower limbs and the arm strength of forward movement. Actively stretching and extending ankle and knee joints ensure the major muscle power to successfully push off the ground. In the movement of arms, pulling the thighs forward and tightening the knees also generate essential muscle power in the action. Therefore, during the training exercise, the muscle strength of triceps surae of the lower limbs, group before the calf muscles, quadriceps, and iliopsoas muscles should be greatly improved.

The activation reactions of methane mediated by metal carbide ions MC3+ (M = Ir and Pt) were comparatively studied at room temperature using the techniques of mass spectrometry in conjunction with theoretical calculations. MC3+ (M = Ir and Pt) ions reacted with CH4 at room temperature forming MC2H2+/C2H2 and MC4H2+/H2 as the major products for both systems. Besides that, PtC3+ could abstract a hydrogen atom from CH4 to generate PtC3H+/CH3, while IrC3+ could not. Quantum chemical calculations showed that the MC3+ (M = Ir and Pt) ions have a linear M-C-C-C structure. The first C–H activation took place on the Ir atom for IrC3+. The terminal carbon atom was the reactive site for the first C–H bond activation of PtC3+, which was beneficial to generate PtC3H+/CH3. The orbitals of the different metal influence the selection of the reactive sites for methane activation, which results in the different reaction channels. This study investigates the molecular-level mechanisms of the reactive sites of methane activation.

The thermal reactivity of the heteronuclear metal-oxide cluster cations [XAlO4 ].+ (X=V, Nb, and Ta) towards methane has been studied by using mass spectrometry in conjunction with quantum mechanical calculations. Experimentally, a hydrogen-atom transfer (HAT) from methane is mediated by all the three oxide clusters at ambient conditions. However, [VAlO4 ].+ is unique in that this cluster directly transforms methane into formaldehyde. The absence of this reaction for the Nb and Ta analogues demonstrates a striking doping effect on the chemoselectivity in the conversion of methane. Mechanistic aspects of the two reactions have been elucidated by quantum-chemical calculations. The HAT reactivity can be attributed to the significant spin density localized at the terminal oxygen atom (Ot.- ) of the cluster ions, while the ionic/covalent character of the Lewis acid-base unit [X-Ob ] plays a crucial role for the generation of formaldehyde. The mechanistic insight derived from this combined experimental/computational investigation may provide guidance for a more rational design of catalysts.

The cancer chemo-preventive effects of equol have been demonstrated for a wide variety of experimental tumours. In a previous study, we found that equol inhibited proliferation and induced apoptotic death of human gastric cancer MGC-803 cells. However, the mechanisms underlying equol-mediated apoptosis have not been well understood. In the present study, the dual AO (acridine orange)/EB (ethidium bromide) fluorescent assay, the comet assay, MTS, western blotting and flow cytometric assays were performed to further investigate the pro-apoptotic effect of equol and its associated mechanisms in MGC-803 cells. The results demonstrated that equol induced an apoptotic nuclear morphology revealed by AO/EB staining, the presence of a comet tail, the cleavage of caspase-3 and PARP and the depletion of cIAP1, indicating its pro-apoptotic effect. In addition, equol-induced apoptosis involves the mitochondria-dependent cell-death pathway, evidenced by the depolarization of the mitochondrial membrane potential, the cleavage of caspase-9 and the depletion of Bcl-xL and full-length Bid. Moreover, treating MGC-803 cells with equol induced the sustained activation of extracellular signal-regulated kinase (ERK), and inhibiting ERK by U0126, a MEK/ERK pathway inhibitor, significantly attenuated the equol-induced cell apoptosis. These results suggest that equol induces mitochondria-dependent apoptosis in human gastric cancer MGC-803 cells via the sustained activation of the ERK1/2 pathway. Therefore, equol may be a novel candidate for the chemoprevention and therapy of gastric cancer.

Summary Necroptosis induction in vitro often requires caspase-8 (Casp8) inhibition by zVAD because pro-Casp8 cleaves RIP1 to disintegrate the necrosome. It has been unclear how the Casp8 blockade of necroptosis is eliminated naturally. Here, we show that pro-Casp8 within the necrosome can be inactivated by phosphorylation at Thr265 (pC8T265). pC8T265 occurs in vitro in various necroptotic cells and in the cecum of TNF-treated mice. p90 RSK is the kinase of pro-Casp8. It is activated by a mechanism that does not need ERK but PDK1, which is recruited to the RIP1-RIP3-MLKL-containing necrosome. Phosphorylation of pro-Casp8 at Thr265 can substitute for zVAD to permit necroptosis in vitro. pC8T265 mimic T265E knockin mice are embryonic lethal due to unconstrained necroptosis, and the pharmaceutical inhibition of RSK-mediated pC8T265 diminishes TNF-induced cecum damage and lethality in mice by halting necroptosis. Thus, phosphorylation of pro-Casp8 at Thr265 by RSK is an intrinsic mechanism for passing the Casp8 checkpoint of necroptosis.

Die thermischen Reaktionen des geschlossenschaligen, “nackten” Gold-Carben-Komplexes [Au(CH2)]+ mit Methan wurden mittels FT-ICR-Massenspektrometrie und quantenchemischen Rechnungen (CCSD(T)//BMK) untersucht. Die effiziente Insertion des Carbenliganden in die C-H-Bindung von Methan wird unter mechanistischen Gesichtspunkten beleuchtet, und die Ursache der unerwartet hohen Reaktivitat von [Au(CH2)]+ gegenuber dem hochst inerten Kohlenwasserstoff diskutiert.

Der Mechanismus der durch den heteronuklearen Oxidcluster [Ga2Mg2O5].+ vermittelten homolytischen Spaltung der O-H-Bindung in Wasser wurde mittels moderner Gasphasenexperimente und quantenchemischer Rechnungen eingehend untersucht. Basierend auf den theoretischen Untersuchungen lassen sich drei Reaktionswege unterscheiden: Neben der klassischen Ubertragung eines Wasserstoffatoms (hydrogen-atom transfer, HAT) auf ein radikalisches Sauerstoffatom existieren zwei mechanistisch unterschiedliche, protonengekoppelte Elektronenubertragungen (proton-coupled electron transfer, PCET). Nach Koordination des Wassermolekuls an ein Magnesiumatom des Clusters zeichnet sich der energetisch gunstigste Reaktionsweg durch einen intramolekularen Protonentransfer auf das freie Elektronenpaar eines verbruckenden Sauerstoffatoms sowie durch eine Reorganisation der Elektronenstruktur des Clusters aus. Dabei werden zwei strukturell identische OH-Gruppen generiert, von denen eine – in Ubereinstimmung mit Isotopenmarkierungsexperimenten – im weiteren Verlauf der Reaktion abgespalten wird.

Mechanistic aspects of an unusual reaction of [HoC6 H4 S](+) with CH3 X (X=Cl, Br, I) have been investigated using Fourier-transform ion cyclotron resonance mass spectrometry combined with density functional theory (DFT) calculations. In this thermal process, all four bonds of the methyl halides are cleaved.

Mechanistic insight into the homolytic cleavage of the O-H bond of water by the heteronuclear oxide cluster [Ga2 Mg2 O5 ](.+) has been derived from state-of-the-art gas-phase experiments in conjunction with quantum chemical calculations. Three pathways have been identified computationally. In addition to the conventional hydrogen-atom transfer (HAT) to the radical center of a bridging oxygen atom, two mechanistically distinct proton-coupled electron-transfer (PCET) processes have been identified. The energetically most favored path involves initial coordination of the incoming water ligand to a magnesium atom followed by an intramolecular proton transfer to the lone-pair of the bridging oxygen atom. This step, which is accomplished by an electronic reorganization, generates two structurally equivalent OH groups either of which can be liberated, in agreement with labeling experiments.

The reactivity of the heteronuclear oxide cluster [Ga2 Mg2 O5 ](.+) , bearing an unpaired electron at a bridging oxygen atom (Ob (.-) ), towards methane and ethane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Hydrogen-atom transfer (HAT) from both methane and ethane to the cluster ion is identified experimentally. The reaction mechanisms of these reactions are elucidated by state-of-the-art quantum chemical calculations. The roles of spin density and charge distributions in HAT processes, as revealed by theory, not only deepen our mechanistic understanding of CH bond activation but also provide important guidance for the rational design of catalysts by pointing to the particular role of doping effects.

Der heteronukleare Oxidcluster [Ga2Mg2O5].+, der ein ungepaartes Elektron an einem verbruckenden Sauerstoffatom (Ob.−) besitzt, wurde mittels Fouriertransformations-Ionenzyklotronresonanz-Massenspektrometrie (FT-ICR-MS) auf seine Reaktivitat gegenuber Methan und Ethan untersucht. In diesen Experimenten wird sowohl in der Reaktion mit Methan als auch mit Ethan die Ubertragung eines Wasserstoffatoms (hydrogen-atom transfer, HAT) vom Substrat auf den Cluster beobachtet. Die Reaktionsmechanismen konnten durch quantenchemische Rechnungen aufgeklart werden. Die durch die theoretischen Untersuchungen verdeutlichte Rolle von Spindichte und Ladungsverteilung fur HAT-Prozesse vertieft das mechanistische Verstandnis von C-H-Bindungsaktivierungen und stellt zudem eine wichtige Orientierung fur das rationale Design von Katalysatoren unter besonderer Betonung von Dotierungseffekten dar.

The novel amino(imino)germylene 1 was prepared by the conversion of HNIPr (NIPr = bis(2,6-diisopropylphenyl)imidazolin-2-imino) with 1 equiv. of Ge[N(SiMe3)2]2. Germylene 1 reacts with B(C6F5)3 to afford the borate salt 2(+)[MeB(C6F5)3](-) in a methyl-abstraction and ring-closing reaction. The conversion of 2 with Fe2(CO)9 furnishes the germylene iron carbonyl complex 3 with a trigonal planar-coordinate germanium atom.

Reactions of vanadium oxide cluster cations with methane in a fast-flow reactor were investigated with a time-of-flight mass spectrometer. Hydrogen atom abstraction (HAA) reactions were identified over stoichiometric cluster cations (V2O5)N+ for N as large as 11, and the relative reactivity decreases as the cluster size increases. Density functional calculations were performed to study the structural, bonding, and electronic properties of the stoichiometric oxide clusters with the size N = 2–6. The geometric structures were obtained by means of topological and structural unit analyses together with global optimizations. Two types of oxygen-centered radicals were found in these clusters, which are active sites of the clusters in reactions with CH4. The size-dependent reactivity is rationalized by the charge, spin, and structural effects. This work is among the first reports that HAA from CH4 can take place on nanosized oxide clusters, which makes a bridge between the small reactive species and inert conden...

Yin Yang 1 (YY1) is a multifunctional DNA-binding transcription factor shown to be critical in a variety of biological processes, and its activity and function have been shown to be regulated by multitude of mechanisms, which include but are not limited to post-translational modifications (PTMs), its associated proteins and cellular localization. YY2, the paralog of YY1 in mouse and human, has been proposed to function redundantly or oppositely in a context-specific manner compared with YY1. Despite its functional importance, how YY2’s DNA-binding activity and function are regulated, particularly by PTMs, remains completely unknown. Here we report the first PTM with functional characterization on YY2, namely lysine 247 monomethylation (K247me1), which was found to be dynamically regulated by SET7/9 and LSD1 both in vitro and in cultured cells. Functional study revealed that SET7/9-mediated YY2 methylation regulated its DNA-binding activity in vitro and in association with chromatin examined by chromatin immunoprecipitation coupled with sequencing (ChIP-seq) in cultured cells. Knockout of YY2, SET7/9 or LSD1 by CRISPR (clustered, regularly interspaced, short palindromic repeats)/Cas9-mediated gene editing followed by RNA sequencing (RNA-seq) revealed that a subset of genes was positively regulated by YY2 and SET7/9, but negatively regulated by LSD1, which were enriched with genes involved in cell proliferation regulation. Importantly, YY2-regulated gene transcription, cell proliferation and tumor growth were dependent, at least partially, on YY2 K247 methylation. Finally, somatic mutations on YY2 found in cancer, which are in close proximity to K247, altered its methylation, DNA-binding activity and gene transcription it controls. Our findings revealed the first PTM with functional implications imposed on YY2 protein, and linked YY2 methylation with its biological functions.

The carbon suboxide cation C3O2+ and the protonated carbon suboxide HC3O2+/DC3O2+ were produced in the gas phase. The vibrational spectra were measured via infrared photodissociation spectroscopy of their argon- or CO-tagged complexes. Spectroscopic evidence combined with state-of-the-art quantum chemical calculations indicate that both cations have a bent C2v symmetry and can be designated as dicarbonyls of a carbon cation and methylidyne cation, respectively.

Necroptosis is mediated by a signaling complex called necrosome, containing receptor-interacting protein (RIP)1, RIP3, and mixed-lineage kinase domain-like (MLKL). It is known that RIP1 and RIP3 form heterodimeric filamentous scaffold in necrosomes through their RIP homotypic interaction motif (RHIM) domain-mediated oligomerization, but the signaling events based on this scaffold has not been fully addressed. By using inducible dimer systems we found that RIP1-RIP1 interaction is dispensable for necroptosis; RIP1-RIP3 interaction is required for necroptosis signaling, but there is no necroptosis if no additional RIP3 protein is recruited to the RIP1-RIP3 heterodimer, and the interaction with RIP1 promotes the RIP3 to recruit other RIP3; RIP3-RIP3 interaction is required for necroptosis and RIP3-RIP3 dimerization is sufficient to induce necroptosis; and RIP3 dimer-induced necroptosis requires MLKL. We further show that RIP3 oligomer is not more potent than RIP3 dimer in triggering necroptosis, suggesting that RIP3 homo-interaction in the complex, rather than whether RIP3 has formed homo polymer, is important for necroptosis. RIP3 dimerization leads to RIP3 intramolecule autophosphorylation, which is required for the recruitment of MLKL. Interestingly, phosphorylation of one of RIP3 in the dimer is sufficient to induce necroptosis. As RIP1-RIP3 heterodimer itself cannot induce necroptosis, the RIP1-RIP3 heterodimeric amyloid fibril is unlikely to directly propagate necroptosis. We propose that the signaling events after the RIP1-RIP3 amyloid complex assembly are the recruitment of free RIP3 by the RIP3 in the amyloid scaffold followed by autophosphorylation of RIP3 and subsequent recruitment of MLKL by RIP3 to execute necroptosis.

The gas-phase reactivity of [V2O5]+ and [Nb2O5]+ towards ethane has been investigated by means of mass spectrometry and density functional theory (DFT) calculations. The two metal oxides give rise to the formation of quite different reaction products; for example, the direct room-temperature conversions C2H6→C2H5OH or C2H6→CH3CHO are brought about solely by [V2O5]+. In distinct contrast, for the couple [Nb2O5]+/C2H6, one observes only single and double hydrogen-atom abstraction from the hydrocarbon. DFT calculations reveal that different modes of attack in the initial phase of CH bond activation together with quite different bond-dissociation energies of the MO bonds cause the rather varying reactivities of [V2O5]+ and [Nb2O5]+ towards ethane. The gas-phase generation of acetaldehyde from ethane by bare [V2O5]+ may provide mechanistic insight in the related vanadium-catalyzed large-scale process.

Although its mechanisms remain unidentified, resveratrol (trans-3,4',5-trihydroxystilbene; RES), which is an active, low molecular-weight compound, possesses a unique antitumor function and is capable of enhancing the cytotoxicity of doxorubicin (DOX) within solid tumor cells. RES is hypothesized to exert these effects by reversing the multidrug resistance (MDR) of the cancer cells in response to chemotherapeutic agents. The aim of the present study was to investigate the reversal effect of RES on MDR in human breast cancer DOX-resistant (MCF-7/DOX) cells and investigate the underlying mechanisms of RES. The results demonstrated that RES inhibited the proliferation of MCF-7/DOX and MCF-7 cells in a dose-dependent manner. Moreover, RES enhanced the cytotoxicity of DOX on MCF-7/DOX cells and the reversal index of RES treatment was demonstrated to be significantly higher when compared with that of the group without RES treatment. In addition, RES was observed to reverse the MDR of the MCF-7/DOX cells and elevate the concentration of DOX in the MCF-7/DOX cells. Furthermore, RES was identified to significantly downregulate the MDR-1 gene and P-glycoprotein expression levels. Reversing MDR, via the downregulation of MDR-1 expression, was concluded to be a mechanism of RES, which enables the unique antitumor function of this polypeptide. Therefore, the present study indicated that RES may be a novel MDR reversal agent for the treatment of breast cancer.

In order to reduce the viscosity of crude oil for transport, we often use the way of heating delivery for high pour point, high wax, and high viscosity oil. Crude oil at high temperature, through long-distance transmission, the temperature and pressure changes on the piping stress greater impact. In this paper, in order to explore the main factor of hot oil pipeline stress and the location of key points, we build the XX hot oil pipeline stress analysis model used CAESAR II software, analysis of the impact of changes in temperature and pressure on piping stress when hot oil pipeline running, draw hot oil pipeline stress distribution, clearly identifies the location of key points of stress concentration, and we have come to that temperature is a major factor in generating pipe stress.

Natural gas pipeline laying process will inevitably go through some of the earthquake-prone areas, these areas of soil subsidence, will cause the pipeline vacant, vacant section of the pipeline failure may cause pipeline rupture. Effects of suspended pipeline stress safety usually have two factors: suspended length and the buoyancy of water. In order to explore the sensitivity of these two factors on suspended pipeline stress, we do numerical simulation of XX suspended pipeline using the general stress analysis software CAESAR II. Research shows that suspended length of pipe is having a greater sensitivity on pipeline stress, and the buoyancy of water is relatively small. The results provide some reference for safety management and selection of pipeline.

The thermal reactivity of the heteronuclear metal-oxide cluster cations [XAlO

The activation of C-H bonds in alkanes is currently a hot research topic in chemistry. The atomic oxygen radical anion (O(-·)) is an important species in C-H activation. The mechanistic details of C-H activation by O(-·) radicals can be well understood by studying the reactions between O(-·) containing transition metal oxide clusters and alkanes. Here the reactivity of scandium oxide cluster anions toward n-butane was studied by using a high-resolution time-of-flight mass spectrometer coupled with a fast flow reactor. Hydrogen atom abstraction (HAA) from n-butane by (Sc2O3)(N)O(-) (N=1-18) clusters was observed. The reactivity of (Sc2O3)(N)O(-) (N=1-18) clusters is significantly sizedependent and the highest reactivity was observed for N=4 (Sc8O13(-)) and 12 (Sc24O37(-)). Larger (Sc2O3)(N)O(-) clusters generally have higher reactivity than the smaller ones. Density functional theory calculations were performed to interpret the reactivity of (Sc2O3)(N)O(-) (N=1-5) clusters, which were found to contain the O(-·) radicals as the active sites. The local charge environment around the O(-·) radicals was demonstrated to control the experimentally observed size-dependent reactivity. This work is among the first to report HAA reactivity of cluster anions with dimensions up to nanosize toward alkane molecules. The anionic O(-·) containing scandium oxide clusters are found to be more reactive than the corresponding cationic ones in the C-H bond activation.

Single, double, triple: Highly selective double H atom abstraction (HAA) from ethane and triple HAA from n-butane by AuNbO(3)(+) clusters have been characterized by mass spectrometry and DFT calculations. The multiple HAAs are initiated by oxygen-centered radicals and promoted by gold. The gold atoms act as electron acceptors during the triple HAAs and help to store a pair of valence electrons between Au and Nb atoms.

In city gas leak detection, common methane detector is vulnerable to gases such as CO, CO2,H 2O and actual conditions of interference (such as humidity, coverings and wind direction), causing false detections and failure judgment. we put the optimization of optical methane detector with infrared absorption principle to replace the traditional combustible gas detector. In order to improve accuracy and efficiency of the gas leak detection, we put forward vehicle-mounted OMDTM optical methane detectors and complementary methane portable RMLDTM laser distance measuring instrument using a new method for gas leak detection. This method is effective to exclude other combustible gases such as methane to leak detection of interference effects, it not only covers the whole of the city gas network, proactively preventing leakage accidents from happening. In the leaks rescue operation, with it, testing vehicles can quickly arrive at the scene to participate to find the leaks, and deal with the leaks as soon as possible. Engineering field application effect suggests that the gas leak detection accuracy rate is higher, low false positive rates, fast response, and it meets the needs of modern urban gas leak detection.

The laying of gas pipeline with tunnel crossing method, except under the influence of pressure, temperature, and out of gas direction, it also subjected to constraints of soil, soil temperature, terrain conditions and the impact of earthquakes. Also crossing pipes are in the constraints of fixed pier, anchorage pier and pier pipeline deformation, which makes the stress analysis of boundary is difficult to determine. In order to compare the effect of different constraints and out of gas direction on the entire tunnel crossing pipeline under operating conditions, this paper has established three pipe models: the symmetrical form of the direction of access to gas, completely without supporting (do not canceled the fixed pier at both ends)and with supporting form, then the primary stress, secondary stress and compound stress are checked in turn. By comparing their impact on the stress of the whole pipeline, we get the importance and extent of the main constrains on the pipeline stress.

The lithium bis(imino)stannylenoid (NIPr)2 Sn(Li)Cl (1; NIPr=bis(2,6-diisopropylphenyl)imidazolin-2-imino) was prepared by the reaction of LiNIPr with 0.5 equiv of SnCl2 ⋅diox (diox=1,4-dioxane) and the ambiphilic character of the compound was demonstrated by investigations into its reactivity. Treatment of 1 with I2 or MeI yielded the oxidative addition products (NIPr)2 SnI2 and (NIPr)2 Sn(Me)I, respectively. In contrast, the reaction of 1 with one equivalent of Me3 SiCl resulted in the formation of Me3 SiNIPr and the chlorostannylene dimer [NIPrSnCl]2 . Moreover, the substitution reaction of compound 1 with MeLi led to the formation of the methyl-substituted stannate (NIPr)2 Sn(Li)Me.

Yin Yang 1 (YY1) is a multifunctional transcription factor shown to be critical in a variety of biological processes. Although it is regulated by multiple types of post-translational modifications (PTMs), whether YY1 is methylated, which enzyme methylates YY1 and hence the functional significance of YY1 methylation remains completely unknown. Here we reported the first methyltransferase, SET7/9 (KMT7), capable of methylating YY1 at two highly conserved lysine (K) residues, K173 and K411, located in two distinct domains, one in the central glycine-rich region and the other in the very carboxyl-terminus. Functional studies revealed that SET7/9-mediated YY1 methylation regulated YY1 DNA-binding activity both in vitro and at specific genomic loci in cultured cells. Consistently, SET7/9-mediated YY1 methylation was shown to involve in YY1-regulated gene transcription and cell proliferation. Our findings revealed a novel regulatory strategy, methylation by lysine methyltransferase, imposed on YY1 protein and linked YY1 methylation with its biological functions.

Oxygen-rich scandium cluster anions ScO(3-5)(-) are prepared by laser ablation and allowed to react with n-butane in a fast-flow reactor. A time-of-flight mass spectrometer is used to detect the cluster distribution before and after the reactions. The ScO(3)(-) and ScO(4)(-) clusters can react with n-butane to produce ScO(3)H(-), ScO(3)H(2)(-), and ScO(4)H(-), while the more oxygen-rich cluster ScO(5)(-) is inert. The experiment suggests that unreactive cluster isomers of ScO(3)(-) and ScO(4)(-) are also present in the cluster source. Density functional theory and ab initio methods are used to calculate the structures and reaction mechanisms of the clusters. The theoretical results indicate that the unreactive and reactive cluster isomers of ScO(3,4)(-) contain peroxides (O(2)(2-)) and oxygen-centered radicals (O(.-)), respectively. The mechanisms and energetics for conversion of unreactive O(2)(2-) to reactive O(.-) species are also theoretically studied.

Scandium oxide cluster cations are prepared by laser ablation and reacted with n -butane in a fast flow reactor. A reflectron time-of-flight mass spectrometer is built to detect the cluster distribution before and after the reactions. Hydrogen atom abstraction (HAA) products (Sc 2 O 3 ) N H + ( N = 1–22), (Sc 2 O 3 ) N O 4 H + ( N = 4–22) and their deuterated compounds are observed upon the cluster interactions with n -C 4 H 10 and n -C 4 D 10 , respectively. This indicates that C–H bond activation of n -butane over atomic clusters as large as Sc 44 O 66 + and Sc 44 O 70 + can take place in gas phase. The experimentally determined rate constants and values of kinetic isotopic effect for HAA vary significantly with the cluster sizes. Density functional theory (DFT) calculations are performed to study the structures and reactivity of small clusters (Sc 2 O 3 ) 1–3 + . The DFT results suggest that the experimentally observed C–H bond activation by (Sc 2 O 3 ) N + is facilitated by oxygen-centred radicals bridgingly bonded in the clusters. The nature of unpaired spin density distributions within the clusters may be responsible for the experimentally observed size-dependent reactivity.

The ion/molecule reactions of molybdenum and tungsten dioxide cations with ethanol have been studied by Fourier transform ion-cyclotron resonance mass spectrometry (FT-ICR MS) and density functional theory (DFT) calculations. Dehydration of ethanol has been found as the dominant reaction channel, while generation of the ethyl cation corresponds to a minor product. Cleary, the reactions are mainly governed by the Lewis acidity of the metal center. Computational results, together with isotopic labeling experiments, show that the dehydration of ethanol can proceed either through a conventional concerted [1,2]-elimination mechanism or a step-wise process; the latter occurs via a hydroxyethoxy intermediate. Formation of C2 H5 (+) takes place by transfer of OH(-) from ethanol to the metal center of MO2 (+) . The molybdenum and tungsten dioxide cations exhibit comparable reactivities toward ethanol, and this is reflected in similar reaction rate constants and branching ratios.