The influence of a single water molecule on the reaction of BrO + HO2.

The influence of a single water molecule on the BrO + HO2 hydrogen extraction reaction has been explored by taking advantage of CCSD(T)/aug-cc-pVTZ//B3LYP/6-311 + + G(d,p) method. The reaction in the absence of water have two distinct kinds of H-extraction channels to generate HOBr + O2 (1Δg) and HBr + O3, and the channel of generation of HOBr + O2 (1Δg) dominated the BrO + HO2 reaction. The rate coefficient of the most feasible channel for the BrO + HO2 reaction in the absence of water is estimated to be 1.44 × 10-11 cm3 molecule-1 s-1 at 298.15 K, which is consistent with the experiment. The introduction of water made the reaction more complex, but the products are unchanged. Four distinct channels, beginning with HO2…H2O with BrO, H2O…HO2 with BrO, BrO…H2O with HO2, H2O…BrO with HO2 are researched. The most feasible channels, stemming from H2O…HO2 with BrO, and BrO…H2O with HO2, are much slower than the reaction of BrO + HO2 without water, respectively. Thus, the existence of water molecule takes a negative catalytic role for BrO + HO2 reaction.

A theoretical study of the gas-phase reactions of propadiene with NO3: mechanism, kinetics and insights.

In this study, the conversion mechanisms and kinetics of propadiene (CH2[double bond, length as m-dash]C[double bond, length as m-dash]CH2) induced by NO3 were researched using density functional theory (DFT) and transition state theory (TST) measurements. The NO3-addition pathways to generate IM1 (CH2ONO2CCH2) and IM2 (CH2CONO2CH2) play a significant role. P3 (CH2CONOCHO + H) was the dominant addition/elimination product. Moreover, the results manifested that one H atom from the -CH2- group has to be abstracted by NO3 radicals, leading to the final product h-P1 (CH2CCH + HNO3). Due to the high barrier, the H-abstraction pathway is not important for the propadiene + NO3 reaction. In addition, the computed ktot value of propadiene reacting with NO3 at 298 K is 3.34 × 10-15 cm3 per molecule per s, which is in accordance with the experimental value. The computed lifetime of propadiene oxidized by NO3 radicals was assessed to be 130.16-6.08 days at 200-298 K and an altitude of 0-12 km. This study provides insights into the transformation of propadiene in a complex environment.

Understanding the insight into the mechanisms and dynamics of the OH-initiated oxidation of CHF2CF2OCHF2 and the subsequent reactions in the presence of NO and O2.

The mechanism and dynamics of CHF2CF2OCHF2 initiated by OH radical evaluated through the density functional theory and variflex code. The solvation pattern of PCM was utilized to analyze the influence of water on the CHF2CF2OCHF2 + OH reaction. The most feasible reaction channel is resulting in the product CF2CF2OCHF2 with H2O by hydrogen abstraction. The computed rate coefficient is consistent with the experimental data. The results turned out that aqueous water act as a disincentive to the title reaction. In the atmosphere, the computation results testified that OH, H2O, NH3 and HCOOH could not accelerate the degradation of the CHF2CF2OCHF2 through OH-initiated in view of the Gibbs free barriers. The research of the follow-up oxidation procedure of the products CHF2CF2OCF2 and CF2CF2OCHF2 with O2/NO reactions indicated that CF2O and CHF2 were the most feasible products. The atmospheric lifetimes of CHF2CF2OCHF2 were in the scope of 71.10-4.74 years in altitude of 0-12 km and at 200-300 K. This research supplies discernment into the conversion of CHF2CF2OCHF2 in a complex environment.

A visual ratiometric fluorescence sensor for glutathione response based on MnO2 nanowires as an oxidant, quencher and recognition unit.

As the "mother of antioxidants", glutathione (GSH) plays an important role in physiological functions. Rapid and accurate monitoring of GSH is of great significance for medicinal chemistry, food chemistry, and clinical medicine. We herein report a visual ratiometric fluorescence sensor based on MnO2 nanowires (MnO2 NWs) as an oxidant, quencher and recognition unit for the determination of GSH. The powerful ratiometric fluorescent probe was constructed by mixing thiamine (VB1) and rhodamine B (RhB) with the help of MnO2 NWs. MnO2 NWs could not only effectively quench the fluorescence of RhB due to the inner filter effect (IFE), but also oxidized non-fluorescent VB1 to blue fluorescent thiochrome (oxVB1). Upon interaction with GSH, the quenched RhB fluorescence could be rapidly restored through decomposition of MnO2 NWs into Mn2+, while the oxVB1 fluorescence decreased, showing an apparent color change from blue to red. The concentration of GSH was proportional to the ratio of fluorescence intensities of RhB and oxVB1, and the detection linear range was 1 to 10 000 µM with comparable selectivity. This ratio fluorescence sensor was successfully applied to GSH determination in whitening capsules and glutathione tablets with satisfactory results, and the sensor may be a potentially powerful tool for the detection of GSH.

The influence of (H2O)1-2 in the HOBr + HO2 gas-phase reaction.

The HOBr + HO2 reaction in the absence of water has three different channels for the abstraction of H to generate the corresponding products. The dominant channel is the generation of BrO + H2O2. The introduction of water molecules influences this dominant reaction via the way the reactants interact with the water molecules. The addition of water molecules decreases the energy barrier and increases the rate coefficient of the reaction. Interestingly, water works as a catalyst and we obtain BrO + H2O2, like in the reaction without water, or the water works as a reactant and we obtain products other than BrO + H2O2. The rate coefficients of the HOBr + HO2 reaction in the presence of water are calculated to be faster than the reaction in the absence of water. However, other pathways in the presence of water are slower than the reaction in the absence of water. The water-assisted effective rate coefficients for the HOBr + HO2 reaction are also larger than those for the reaction in the absence of water. The influence of a water dimer is not as important when compared with one water molecule. In summary, a single water molecule has a positive catalytic influence in enhancing the HOBr + HO2 reaction.

Role of monomolecular water and bimolecular water in IO + CH2O reaction.

A CCSD(T)//B3LYP method was employed to research the influence of monomolecular and bimolecular water molecules on the IO + CH2O reaction. H-abstraction and addition/elimination mechanisms have been located, and the H-abstraction mechanism occupied the whole reaction without water. The introduction of water complicates the reaction, but the final product remains unchanged. Water molecules influence each reaction pathway in six different pathways with monomolecular water and two different pathways with bimolecular water, respectively. The present calculations manifested that water has a positive influence on the IO + CH2O reaction with monomolecular water molecule, and plays negative catalytic influence on the IO + CH2O reaction with bimolecular water molecule. The effective rate constants are much lower than the IO + CH2O reaction without water.

The influence of a single water molecule on the reaction of BrO + HONO.

Quantum chemical computations and transition state theory are employed to systematically research the influence of a single molecule water on the BrO + HONO reaction. Two distinct reactions, namely BrO + trans-HONO and BrO + cis-HONO are explored for the reaction in the absence of water, which is mainly decided by the configuration of HONO. With introduction a single water molecule to the reaction, the rate coefficient of the channel starting from BrO + cis-HONO and BrO + trans-HONO are 2.43 × 10-19 and 5.22 × 10-22 cm3 molecule-1 s-1, which is larger than the reaction in the absence of water. For further comprehend the impact of water on the BrO + HONO reaction, it is necessary to compute the effective rate coefficient by taking into account the concentration of water. The water-assisted effective rate coefficients for the BrO + HONO reaction are smaller than that the reaction in the absence of water. The reaction of BrO with cis-HONO is feasible both in absence and existence of water.

Fast Synthesis of Graphene Oxide-ß-Lactam as a Residue-Free Environmental Bacterial Inhibitor.

Common pathogenic bacteria contaminate the environment through various modes of transmission. It is thus crucial to develop simple preparation methods of residue-free environmental disinfectants. ß-Lactam antibiotics are frequently prescribed in clinical practice to treat bacterial infections. In this study, we used electrochemical exfoliation to synthesize graphene oxide (GO) with abundant ketene functional groups. A residue-free GO-ß-lactam (GOßL) was subsequently obtained by mixing ketene and azomethine-H via a [2 + 2] cycloaddition reaction in the aqueous phase. GOßL has shown broad-spectrum bacterial inhibition against four bacteria (Staphylococcus aureus, Escherichia coli, Salmonella enterica, and Shigella dysenteriae), and it degrades rapidly within 24 h. This study provides a fast and easy method for the synthesis of GOßL, which can be employed as a promising environmental bacteriostatic disinfectant in real-life applications.

SNF5 promotes cell proliferation and immune evasion in non-small cell lung cancer.

Immune evasion is the process that tumor cells accelerate growth and metastasis by evading the recognition and attack of immune cells. SNF5 is one of the core subunits of SWI/SNF, which is involved in the development of a variety of malignancies. However, the functions of SNF5 in Non-Small Cell Lung Cancer (NSCLC) and the mechanism of SNF5 regulates immune evasion are still unclear. Based on this, we analyzed the expression of SNF5 and overall survival of lung cancer tissues through the cancer genome atlas (TCGA) database. Then we performed genetic gain and loss of function experiments with SNF5 using lentivirus infection and siRNA in NSCLC A549 and NCI-H1299 cells, respectively. We investigated the proliferation and immune evasion of these cells. We further explored the mechanism of SNF5 on NSCLC cells immune evasion. Our data showed that SNF5 was significantly increased in lung cancer tissues than that in normal lung tissues. Furthermore, SNF5 promoted NSCLC cells proliferation and the expressions of immune evasion-related genes. Meantime, overexpressed SNF5 reduced mortality of A549 cells when co-cultured with T cells. Moreover, SNF5 regulated the immune evasion by activating the signal transducer and activator of transcription (STAT3)/ phospho-STAT3 pathway in NSCLC cells. Together, our results validate SNF5 as a tumor oncogene and provide a new target for NSCLC treatment.

SNF5, a core subunit of SWI/SNF complex, regulates melanoma cancer cell growth, metastasis, and immune escape in response to matrix stiffness.

Increased stiffness of the extracellular matrix is an important hallmark of melanoma development and progression, but its regulatory role and related mechanisms remain unclear. We adapted polydimethylsiloxane (PDMS)-micropillar-based matrix platform and investigated the effect of matrix stiffness on the proliferation, epithelial-mesenchymal transition (EMT), and immune escape of melanoma cells. We observed a stiff matrix enhanced cell proliferation, EMT, and immune escape of A375 cells. Furthermore, the expression of SNF5 on the stiffer matrix was higher than that on the softer matrix. Next, we investigated whether SNF5 is an important transducer in response to matrix stiffness. Our results revealed that knockdown of SNF5 significantly decreased stiff matrix-induced activation of cell proliferation, EMT and immune escape. Meanwhile, the overexpression of SNF5 showed its ability to increase cell proliferation, invasion and immune escape by activating the STAT-3 pathway in vitro. Furthermore, SNF5 deficiency elevated the level of tumor-infiltrating CD8+T cells and decreased the number of PD-L1 positive cells in vivo. Together, our findings suggested that stiffer substrate enhanced melanoma development by upregulating SNF5 expression, and SNF5 is a key mediator of stiffer matrix-induced immune evasion of melanoma cancer cells.

Theoretical investigations on mechanisms and kinetics of methylketene with O(3P) reaction in the atmosphere.

The O(3P)-initiated conversion mechanism and dynamics of CH3CHCO were researched in atmosphere by executing density functional theory (DFT) computations. Optimizations of all the species and single-point energy computations were implemented at the B3LYP/6-311++G(d,p) and CCSD(T)/cc-pVTZ level, respectively. The explicit oxidation mechanism was introduced and discussed. The results state clearly that the O(3P) association was more energetically beneficial than the abstraction of H. The rate coefficients over the probable temperature range of 200-3000 K were forecasted by implementing Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Specifically, the total rate coefficient of O(3P) association reactions is 1.19 × 10-11 cm3 molecule-1 s-1 at 298 K, which is consistent with the experimental results (1.16 × 10-11 cm3 molecule-1 s-1). The rate coefficients for the O(3P) with CH2CO, CH3CHCO, and (CH3)2CCO suggest that rate coefficient of ketene derivatives increase with the increase of methylation degree. Graphical abstract.

Competing endogenous RNAs in lung cancer.

Competing endogenous RNAs (ceRNAs) containing microRNA response elements can competitively interact with microRNA via miRNA response elements, which can combine non-coding RNAs with protein-coding RNAs through complex ceRNA networks. CeRNAs include non-coding RNAs (long non-coding RNAs, circular RNAs, and transcribed pseudogenes) and protein-coding RNAs (mRNAs). Molecular interactions in ceRNA networks can coordinate many biological processes; however, they may also lead to ceRNA network imbalance and thus contribute to cancer occurrence when disturbed. Recent studies indicate that many dysregulated RNAs derived from lung cancer may function as ceRNAs to regulate multitudinous biological functions for lung cancer, including tumor cell proliferation, apoptosis, growth, invasion, migration, and metastasis. This study therefore reviewed the research progress in the field of non-coding and protein-coding RNAs as ceRNAs in lung cancer, and highlighted validated ceRNAs involved in biological lung cancer functions. Furthermore, the roles of ceRNAs as novel prognostic and diagnostic biomarkers were also discussed. Interpreting the involvement of ceRNAs networks in lung cancer will provide new insight into cancer pathogenesis and treatment strategies.

Synthesis of CoTe nanowires: a new electrode material for supercapacitor with high stability and high performance.

Highly dispersed CoTe electrode material were successfully prepared by using a facile one-step solvothermal process without any surfactants. Compared with the conventional hydrothermally prepared irregularly-shaped CoTe, a regular nanowire-formed CoTe can be obtained by a solvothermal process using ethylene glycol as a solvent. The prepared CoTe nanowire electrode can exhibit a relatively high specific capacity of 643.6 F g-1 at a current density of 1 A g-1 and remarkable cyclic stability with 76.9% of its specific capacitance retention after 5000 cycles at a high current density of 5 A g-1. Besides, even at the high current density of 20 A g-1, the specific capacitance of CoTe nanowire electrode still has 90.2% retention relative to 1 A g-1, showing an excellent rate performance. In order to enlarge the potential window to increase the energy density, an asymmetric supercapacitor (ASC) is assembled by applying CoTe nanowires and activated carbon as the positive electrode and the negative electrode in 3 M KOH, which can enlarge the operating voltage to as high as 1.6 V, and shows a specific capacity of 92.5 F g-1 with an energy density of 32.9 Wh kg-1 and power density of 800.27 W kg-1 at 1 A g-1, and even after 5000 cycles of charge/discharge at 5 A g-1, the ASC still retains 90.5% of its initial specific capacitance, showing excellent cycle stability.

Self-enhanced electrogenerated chemiluminescence of ruthenium(II) complexes conjugated with Schiff bases.

In this work, we obtain two ruthenium(ii) complexes with Schiff base cavities that exhibit significantly enhanced electrochemiluminescence (ECL) intensity and quantum efficiency due to Ru(bpy)3(2+) in aqueous solution, without the addition of tri-n-propylamine (TPrA). The great increase in ECL intensity is confirmed to be due to the electrochemical oxidation of phenolic hydroxyl groups and the resonant structure of imino radicals. Thus, the electrons are transferred intramolecularly to the Ru(iii) center, leading to efficient generation of the excited state of Ru(ii)*. Subsequently, we find that Co(2+) bonding with the salen cavity can selectively and quickly quench the ECL signal. Furthermore, we study the mechanism of the process by which Co(2+) hinders the oxidation of phenolic groups and blocks the electron transfer from imino radicals to the Ru center. Thus, a highly sensitive and selective ECL probe for the recognition of Co(2+) was developed with a stable response over a concentration range of 0.9 µM to 6.3 µM and a detection limit as low as 21 nM.

Adsorption of HCN on reduced graphene oxides: a first-principles study.

The interactions between HCN and reduced graphene oxides (rGO) are investigated using first-principles calculations with M06-2X functional. The results show that the adsorption of HCN on rGO is generally stronger than that on graphene, which is due to the presence of the active defect sites in rGO, such as the hydroxyl, epoxide, and carboxyl functional groups and even the carbon atom near these groups. The interaction between HCN and rGO with oxygen-containing group can result in the formation of hydrogen bonds, N · · · H and O · · · H. The adsorption of HCN on rGO depends on the type and location of oxygen-containing group in rGO. Carboxyl group on rGO is much more attractive for HCN than hydroxyl and epoxide group. The adsorption of HCN is much stronger in rGO with oxygen-containing group on the surface than that at the edge. The adsorption of HCN on rGO with carboxyl attached to vacancy on the surface is the strongest.

A time-dependent DFT study of the absorption and fluorescence properties of graphene quantum dots.

Absorption and fluorescence spectra of graphene quantum dots (GQDs) have been computed by using time-dependent density functional theory (TDDFT). Different functionals, including PBE, TPSSh, B3LYP, PBE0, CAM-B3LYP, and LC-ωPBE, have been tested and B3LYP/6-31G(d) has been proven to be the most accurate method for our work. The bulk solvent effects of toluene and dichloromethane have been assessed by using the polarizable continuum model (PCM). The absorption wavelength of GQDs in solvents is red-shifted compared with that in the gas phase. Edge functionalization effects analysis shows that a small number of substituted groups on GQDs induce a small redshift whereas a large redshift occurs when the edges of GQDs are all decorated. Little difference in the fluorescent emission was observed in solvents and in the gas phase. Molecular orbital transition and transition density matrix analysis have been performed. The electronic transition mainly occurs in the middle part of the structure of C132. The strong absorption of C132 corresponds to a S0 →S3 transition and the fluorescence emission is ascribed to a S1 →S0 transition, which indicates that Kasha's rule is obeyed.

Effects of edge oxidation on the stability and half-metallicity of graphene quantum dots.

A comprehensive first-principles theoretical study of the electronic properties and half-metallic nature of zigzag edge-oxidized graphene quantum dots (GQDs) is carried out by using density functional theory (DFT) with the screened exchange hybrid functional of Heyd, Scuseria and Ernzerhof (HSE06). The oxidation schemes include -OH, -COOH and -COO groups. We identify oxidized GQDs whose opposite spins are localized at the two zigzag edges in an antiferromagnetic-type configuration, showing a spin-polarized ground state. Oxidized GQDs are more stable than the corresponding fully hydrogenated GQDs. The partially hydroxylated and carboxylated GQDs with the same size exhibit half-metallic state under almost the same electric-field intensity whereas fully oxidized GQDs behave as spin-selective semiconductors. The electric-field intensity inducing the half metal increases with the length of the partially oxidized GQDs, ranging from M=4 to 7.

QSAR study for cytotoxicity of diterpenoid tanshinones.

A quantitative structure-activity relationship (QSAR) of a series of tanshinone compounds with cytotoxicity against murine leukemia cell lines P-388 has been studied using density functional theory (DFT) method combined with statistical analysis. Four main independent factors contributing to the cytotoxicity including the maximum molecular electrostatic potential at the SAS surface (SAS (max)), the average nucleophilic superdelocalizability (ANS), the dihedral between ring A and B (u) and the net atomic charge of C (12) (Q(C (12))) were selected by stepwise multiple regression method, then the QSAR equation was established via multiple linear regression (MLR) analysis. These descriptors accounted for 74.2% of the variation in the in vitro biological activity among the tanshinone analogues. The QSAR equation was used to estimate the cytotoxicity for new compounds of this series by calculating the four descriptors. Based on this model, six new compounds with higher cytotoxicity were theoretically designed.

Direct electrodeposition of gold nanoparticles on indium tin oxide surface and its application.

Gold nanoparticles (GNPs) were direct deposited onto the surface of indium tin oxide (ITO) electrode surface through cyclic voltammetric method. The GNPs-modified ITO electrodes were characterized by means of scanning electron microscopy (SEM), UV-vis spectroscopy and electrochemical methods. The quasi-spherical GNPs directly attached on the electrode surface with a relatively small size and a quite narrow distribution. Cyclic voltammetry and linear sweep voltammetry of glucose on the modified electrodes were performed. The GNPs-modified ITO electrodes showed high electrocatalytic reactivity towards glucose oxidation in 0.01 M NaOH and 0.05 M phosphate buffer solution (pH 7.4). The GNPs-modified transducer was successfully used for the amperometric sensing of glucose at alkaline and neutral solutions.