Exploration of spatial confinement and ligand effects for the oxygen reduction reaction on Fe-Nx embedded hole-graphene.

In this work, we constructed theoretical models by embedding Fe-TCPP and Fe-(mIM)n (n = 2,3,4) active sites into hole-graphene, and the structural stability was evaluated using molecular dynamics simulations. Based on the theoretical models, we systematically studied the oxygen reduction reaction (ORR) mechanism and the effect of spatial confinement and ligands with DFT calculations. The analysis of the ORR reaction pathway shows that Fe-TCPP and Fe-(mIM)4 have good catalytic activity. Subsequently, the confinement effect (5-14 Å) was introduced to investigate its influence on the catalytic activity. The Fe-TCPP and Fe-(mIM)4 active sites have the lowest overpotential at an axial space of 8 Å and 9 Å, respectively. We select four ligands (bpy, pya, CH3, and bIm) to explore their effect on the catalytic activity of the Fe-TCPP active site. With the modification of bpy, pya, and bIm_N (Fe-N4 sites become Fe-N5 active sites), the overpotential decreases by 26-31%. In the present work, the best catalytic system is Fe-TCPP_pya, which is on the top of the volcano plot.

Combined DFT and kinetic Monte Carlo study of a bridging-spillover mechanism on fluorine-decorated graphene.

In this work, combining first-principles calculations with kinetic Monte Carlo (KMC) simulations, we constructed an irregular carbon bridge on the graphene surface and explored the process of H migration from the Pt catalyst to carbon bridge, and further migration to the graphene surface. The calculated reaction diagrams show that the hydrogen atoms can easily migrate from the Pt cluster to the carbon bridge with a low barrier of 0.22-0.86 eV, and KMC simulations indicate that the migration reactions can take place at intermediate temperatures (91.9-329.5 K). Our research clarified the role of the carbon bridge: (1) the close combination of Pt clusters and carbon bridges reduces H2 adsorption enthalpy, which facilitates the spillover of H atoms from the Pt cluster to the carbon bridges and (2) the unsaturated carbon atoms on the carbon bridges have radical character and tend to bind radical H atoms. The subsequent study shows that the F atoms decorated on graphene can greatly reduce the migration barrier of H atoms from the carbon bridge to graphene. With F atoms decorated, the carbon atoms are in an electron-deficient state, which have a strong ability to bind the hydrogen atoms, and it promotes the migration of H atoms to the graphene surface. The migration barrier and reaction temperature are reduced to 0.72 eV and 279 K, respectively.

Hydrogen spillover mechanism on covalent organic frameworks as investigated by ab initio density functional calculation.

The hydrogen spillover mechanism, including the H chemisorption, diffusion, and H(2) associative desorption on the surface of COFs and H atoms migration from metal catalyst to COFs, have been studied via density functional theory (DFT) calculation. The results described herein show that each sp(2) C atom on COFs' surface can adsorb one H atom with the bond length d(C-H) between 1.11 and 1.14 Å, and the up-down arrangement of the adsorbed H atoms is the most stable configuration. By counting the chemisorption binding sites for these COFs, we can predict the saturation storage densities. High hydrogen storage densities show that the gravimetric uptakes of COFs are in the range of 5.13-6.06 wt%. The CI-NEB calculations reveal that one H atom diffusing along the C-C path on HHTP surface should overcome the 1.41-2.16 eV energy barrier. We chose tetrahedral Pt(4) cluster and HHTP as the representative catalyst and substrate, respectively, to study the H migration from metal cluster to COFs. At most, two H atoms can migrate from Pt(4) cluster to HHTP substrate. The migration reaction is an endothermic process, undergoing an activation barrier of 1.87 eV and 0.57 eV for the first and second H migration process, respectively. Three types of H(2) associative desorption from hydrogenated COFs were studied: (I) the two H adatoms recombining to one H(2) molecule with a recombination barrier of 4.28 eV, (II) the abstraction of adsorbed H atoms by gas-phase hydrogen atoms through ER type recombination reactions with a recombination barrier of 1.05 eV, (III) the H(2) desorption through the reverse spillover mechanism with an energy barrier of 2.90 eV.

New Li-doped fullerene-intercalated phthalocyanine covalent organic frameworks designed for hydrogen storage.

Applying density functional theory (DFT) calculations, we have designed fullerenes (C20, C24, C26, C28, C30, C36, C60 and C70) intercalated phthalocyanine covalent organic frameworks (Cn-Pc-PBBA COFs). First principles molecular dynamics (MD) simulations showed that the structures of Cn-Pc-PBBA COFs are stable at room temperature and even at higher temperature (500 K). The interlayer distance of Pc-PBBA COF has been expanded to 7.48-13.25 Å by the intercalated fullerenes, and the pore volume and surface area were enlarged by 2.3-3.1 and 2.0-2.6 times, respectively. The grand canonical Monte Carlo (GCMC) simulations show that our designed Cn-Pc-PBBA COFs exhibit a superior hydrogen storage capability: at 77 K and P = 100 bar, the hydrogen gravimetric and volumetric uptakes reach 9.4-12 wt% and 48.1-52.2 g L(-1), respectively. To meet the requirement for practical application in hydrogen storage, we use the Li-doping method to modify the hydrogen storage performance of Cn-Pc-PBBA COFs. Our results show that the Li atoms can stably locate on the surface of C30-, C36, C60 and C70-Pc-PBBA COFs. At T = 298 K and P = 100 bar, for these four Li-doped Cn-Pc-PBBA COFs, the gravimetric and volumetric uptakes of H2 reach 4.2 wt% and 18.2 g L(-1), respectively.

Quietness of circular RNA circ_0054633 alleviates the inflammation and proliferation in lipopolysaccharides-induced acute lung injury model through NF-κB signaling pathway.

AIM: Acute lung injury (ALI) is the mild form of acute respiratory distress syndrome (ARDS) which is a common lung disease with a high incidence and mortality rate. Recent studies manifested that some circular RNAs were associated with ALI. In this study, we aimed to uncover the effect of circular RNA circ_0054633 on ALI initiation and progression and proposed a new mechanism related to ALI. METHODS: The lipopolysaccharides (LPS)-induced acute lung injury model were build both in vivo of rat and in vitro of primary murine pulmonary microvascular endothelial cells (MPVECs). Hematoxylin and eosin (H&E) was employed to observe the tissue morphology and estimate the degree of lung damage. We used real-time quantitative polymerase chain reaction (RT-qPCR) to measure the expression level of circ_0054633. The expression levels of inflammatory cytokines IL-17A and tumor necrosis factor-α (TNF-α) were detected by ELISA. The effects of circ_0054633 on MPVECs proliferation and apoptosis were detected with the help of CCK-8 and apoptosis assay, separately. The expression level of NF-κB p65 protein was measured by Western blot. RESULTS: circ_0054633, IL-17A, TNF-α and NF-κB p65 were all overexpressed in LPS-treated rat and MPVECs, and LPS enhanced the proliferation and apoptosis of MPVECs. While circ_0054633 silencing reversed the above promotion effects of LPS on IL-17A, TNF-α expression and MPVECs proliferation and apoptosis. CONCLUSIONS: Quietness of circ_0054633 alleviated LPS-induced ALI via NF-κB signaling pathway, implicating circ_0054633 may be a potential biomarker for diagnose and therapy of ALI.

[Optical parameters of Er3+ in Er3+ : YVO4].

In the present paper the authors firstly measured the absorption spectra of Er3+ in the sample Er3+ : YVO4 (0.5%), then calculated the intensity parameters are calculated by using the Judd-Ofelt theory. After that the authors dealed with some predicted spectroscopic parameters, such as the oscillator strength, spontaneous radiative transition rate, branching ratio and integrated emission cross section. And Er : YVO4 crystal application value has been analyzed with the optical parameters. Especially there are large oscillator strengths and large integrated emission cross sections in the transitions of 4 I1/2 --> 4 I15/2, 2 H11/2 --> 4I15/2, 4S3/2 --> 4 I15/2, and 4F9/2 --> 4 I15/2. So, they are more worth of attention. Moreover, by comparing the Er-doped yttrium vanadate crystal and other Er-doped crystal optical properties, the authors can see the advantages of YVO4 as laser crystal. Finally, the authors discussed the splitting of the energy levels of Er3+ in the crystal YVO4 based on the group theory.

Combined pretreatment serum CA19-9 and neutrophil-to-lymphocyte ratio as a potential prognostic factor in metastatic pancreatic cancer patients.

The aim of this study was to explore the role of combined pretreatment serum carbohydrate antigen 19-9 (CA19-9) and neutrophil-to-lymphocyte ratio (NLR) as potential prognostic factors in metastatic pancreatic cancer patients.We investigated pretreatment serum CA19-9 and NLR in 59 metastatic pancreatic cancer patients, determined the patients' thresholds by receiver operating characteristic curve analysis, and assessed their prognostic values by Kaplan-Meier curve and Cox regression models.Results of multivariate analysis showed high CA19-9, high NLR, and high score (the scoring system of CA19-9 and NLR) were significantly correlated with overall survival. Area under the curve of the scoring system was higher than that of CA19-9 or NLR.Combined pretreatment serum CA19-9 and NLR is a better prognostic biomarker of metastatic pancreatic cancer patients than CA19-9 or NLR alone.

[Effect of clozapine and risperidone on serum cytokine levels in patients with first-episode paranoid schizophrenia].

OBJECTIVE: To study the effects of clozapine and risperidone on serum cytokine levels in patients with first-episode paranoid schizophrenia, and explore the role of the cytokines in the psychopathological basis of the illness. METHOD: Fifty-eight patients with first-episode paranoid schizophrenia were treated with either clozapine or risperidone, and before and at the end of the 4th, 8th weeks and 6th months after the medication respectively, the serum levels of interleukin (IL)-6, 2, 18,and tumor necrosis factor (TNF)alpha were measured with enzyme-linked immunosorbent assay (ELISA). The Positive and Negative Syndrome Scale (PANSS) was used to evaluate the psychotic symptoms. RESULT: In patients treated with risperidone, the levels of serum IL-6 and IL-2 after 4 weeks, TNFalpha after 8 weeks, and IL-18 after 6 months were all significantly lowered in comparison with the pretreatment levels (P<0.01 or 0.05). In clozapine group, the levels of IL-2 after 4 weeks and IL-6 and IL-18 after 6 months were lowered significantly (P<0.01 or 0.05). Before the medication, serum IL-6 level was positively correlated with Positive Syndrome scores (r=0.386, P<0.01), IL-2 with the total score and Positive Syndrome scores (r=0.338, 0.305; P<0.01, 0.05), and TNFalpha with the total score (r=0.283, P<0.05). The changes of IL-2 and IL-6 after 8 weeks was positively correlated with the change of Positive Syndrome scores (r=0.268, 0.375; P<0.05, 0.01). Six months after the medication, the change in IL-6 and TNFalpha levels was positively correlated with the change of total score (r=0.365, 0.362; P<0.05). Before treatment, IL-6 was positively correlated with IL-2 levels (r=0.356, P<0.01), and TNFalpha with IL-18 levels (r=0.291, P<0.05). TNFalpha was positively correlated with IL-6 levels (r=0.332, P<0.01) 8 weeks after the medication. The changes in IL-6 was positively correlated with the those in IL-2 levels 6 months after the medication (r=0.391, P< 0.05). CONCLUSION: Clozapine and risperidone have similar immunosuppression actions and may affect serum IL-6 levels in patients with paranoid schizophrenia, in the psychopathology of which the cytokines play their roles of various importance.

Band gap engineering of chemical vapor deposited graphene by in situ BN doping.

Band gap opening and engineering is one of the high priority goals in the development of graphene electronics. Here, we report on the opening and scaling of band gap in BN doped graphene (BNG) films grown by low-pressure chemical vapor deposition method. High resolution transmission electron microscopy is employed to resolve the graphene and h-BN domain formation in great detail. X-ray photoelectron, micro-Raman, and UV-vis spectroscopy studies revealed a distinct structural and phase evolution in BNG films at low BN concentration. Synchrotron radiation based XAS-XES measurements concluded a gap opening in BNG films, which is also confirmed by field effect transistor measurements. For the first time, a significant band gap as high as 600 meV is observed for low BN concentrations and is attributed to the opening of the π-π* band gap of graphene due to isoelectronic BN doping. As-grown films exhibit structural evolution from homogeneously dispersed small BN clusters to large sized BN domains with embedded diminutive graphene domains. The evolution is described in terms of competitive growth among h-BN and graphene domains with increasing BN concentration. The present results pave way for the development of band gap engineered BN doped graphene-based devices.