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•The screened M-G structures are very thermodynamically stable, and the stability is even higher than that of the corresponding bulk metal surfaces.•The binding energies of ORR ...intermediates suggest that they are not linear dependence, which are different form the cases found on some metal-based catalysts.•The Au-, Co-, and Ag-G structures could be used as the ORR catalysts.
Graphene doping is a promising direction for developing effective oxygen reduction reaction (ORR) catalysts. In this paper, we computationally investigated the ORR performance of 10 kinds of metal-doped graphene (M-G) catalysts, namely, Al-, Si-, Mn-, Fe-, Co-, Ni-, Pd-, Ag-, Pt-, and Au-G. The results shown that the binding energies of the metal atoms incorporated into the graphene vacancy are higher than their bulk cohesive energies, indicating the formed M-G catalysts are even more stable than the corresponding bulk metal surfaces, and thus avoid the metals dissolution in the reaction environment. We demonstrated that the linear relation among the binding energies of the ORR intermediates that found on metal-based materials does not hold for the M-G catalysts, therefore a single binding energy of intermediate alone is not sufficient to evaluate the ORR activity of an arbitrary catalyst. By analysis of the detailed ORR processes, we predicted that the Au-, Co-, and Ag-G materials can be used as the ORR catalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
By means of density functional theory, the ammonia decomposition reactions catalyzed by Ni
13
, Cu
13
, and Ni
12
Cu clusters have been studied and compared. We firstly investigated the structural ...stability of these clusters, and then systematically investigated their ammonia decomposition activity by analyzing the adsorption property of reaction intermediates and the relative energy diagram. The results show that the adsorption energy of reaction intermediate N on Ni
12
Cu cluster is −5.93 eV, which is very close to the optimal value (−5.81 eV) of ammonia decomposition volcano curve. The reaction energy diagram shows that the dehydrogenation of NH intermediate is the rate-determining step for these clusters due to the positive reaction heat. Furthermore, the catalytic property of Ni
12
Cu cluster is interpreted by density of states. It indicates that the adsorption energies of reaction intermediates mainly depend on the d-band center of the clusters.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Purpose
This study elucidated the effect of an inclined spring arrangement on the flow-induced vibration of a circular cylinder to understand if the effect enhances the harnessing of the energy of ...fluid flows.
Method
An experiment was conducted on a circulating water channel. A circular cylinder was partially submerged. It was elastically supported by two springs whose longitudinal directions were varied. With the speed of the water flow varied, the vibrations of the circular cylinder were measured. The measured vibrations were interpreted by la linear dynamic model.
Results and discussion
In a few cases, a jump in response amplitudes from zero to the maximum was observed with the spring inclination at reduced velocities of 6 to 7, whereas gradually increasing response amplitudes were observed in other cases. The inclined spring arrangement achieved greater velocity amplitudes than in cases without spring inclination. A theoretical evaluation of the measured responses indicates that the effect of the inclined springs was caused by geometric nonlinearity; the effect would be more prominent by employing a longer moment lever.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
DNA damage repair and G2/M arrest are the key factors regulating the survival of cancer cells exposed to radiation. Recent studies have shown that long noncoding RNAs (lncRNAs) play important roles ...in a variety of biological processes, including DNA repair, cell cycle regulation, differentiation, and epigenetic regulation. However, the knowledge about the genome scale of lncRNAs and their potential biological functions in tumor cells exposed to radiation are still unclear. In this study, we used LncRNA + mRNA Human Gene Expression Microarray V4.0 to profile lncRNA and messenger RNA (mRNA) from HeLa, MCF-7, and A549 cells after irradiation with 4 Gy of γ-radiation. We identified 230, 227, and 274 differentially expressed lncRNAs and 150, 214, and 274 differentially expressed mRNAs in HeLa, MCF-7, and A549 cells, respectively, among which there are 14 common differentially expressed lncRNAs and 22 common differentially expressed mRNAs in all of the 3 cell lines. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that these differentially expressed mRNAs were mainly associated with cell cycle. Further, we also predicted the target genes and functions of these differentially expressed lncRNAs. Our study on lncRNAs has greatly expanded the field of gene research in the relationship of radiation, cell cycle, and DNA damage.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Nitrogen doped ordered mesoporous carbon (NOMC) with well-defined crystal planes was synthesized by a one-pot aqueous cooperative assembly route. Structural and morphological analysis of the samples ...showed the typical ordered mesoporous structure of the carbon. Ruthenium was anchored by impregnation with ruthenium trichloride, followed by a reduction in H2 flow at 773 K. The HRTEM analysis of the samples showed a more homogeneous dispersion of Ru particles on NOMC than on that of ordered mesoporous carbon (OMC). The catalytic performance of prepared catalysts for ammonia decomposition was evaluated in a fixed bed reactor under atmospheric pressure. Consequently, it was demonstrated that the ruthenium supported on NOMC had higher reactivity than its counterparts on OMC, activated carbon (AC) and carbon nanotubes (CNTs) in ammonia decomposition. The results indicated that nitrogen doped on OMC favored the improvement of active sites and greatly promotion of hydrogen produced from catalyst surface.
•Nitrogen doped ordered mesoporous carbon (NOMC) was used as Ru catalyst carrier for ammonia decomposition.•Ru supported on NOMC was more active for NH3 decomposition than their counterparts on OMC, AC and CNTs.•The presence of nitrogen in NOMC played a positive role in Ru dispersion and desorption of hydrogen.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Detailed density functional theory (DFT) calculations have been carried out to study the ammonia (NH3) decomposition activity and catalytic mechanism for octahedral nickel nanoclusters. Four ...different size nickel nanoclusters, Ni19, Ni44, Ni85 and Ni146, were applied to investigate the nanoscale size effect. The results reveal that these four nickel nanoclusters adopt the same NH3 decomposition mechanism. The predicted catalytic activities of these nickel nanoclusters decrease in the sequence of Ni44 > Ni146 ≈ Ni85 > Ni19, based on the analysis of adsorption energies of NH3 decomposition intermediates and landscapes of NH3 decomposition pathways. Besides, the reaction heat of Ni146 nanocluster is only 0.65 eV in the process of N2 desorption, showing the nature of easy desorption out of the catalyst surface. Moreover, molecular dynamics calculations show that large-size nanoclusters performed better on thermal stability. Combined with dynamics analysis, we found that Ni146 nanocluster possesses not only high thermodynamic stability but also catalytic activity. Electronic structural analysis show that negatively Mulliken charged sites were more favorable for adsorbing N and act as active centers.
•Different size nickel nanoclusters were used to investigate the size effect.•Ni146 nanocluster possesses high thermodynamic stability and catalytic activity.•Negatively Mulliken charged sites act as active centers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Double-strand breaks (DSBs), the most serious lesions of DNA, often induce chromosomal aberrations and are intimately associated with oncogenesis. A normal DNA damage response (DDR) network contains ...two major repair pathways: homologous recombination (HR) and non-homologous end-joining (NHEJ). Studies of DSB repair-associated molecules have focused mainly on DNA repair proteins. However, non-coding RNAs also play important roles in the process of DSB repair. Over the past two decades, microRNAs (miRNAs) have been extensively investigated. Our previous work showed that miR-34c-5p overexpression results in suppression of RAD51 and upregulation of γH2AX. In accordance with this, we confirmed that miR-34s family overexpression increased endogenous DSB levels to different extents, an effect that was further confirmed to be associated with the decreased efficiency of HR repair. In addition, miR-34s overexpression also induced G1 arrest, inhibited proliferation and promoted apoptosis. As a central molecule in the process of HR pathway, RAD51 expression was strongly repressed in cells transfected with the miR-34a/b/c-5p mimic. Finally, we demonstrated that miR-34a/b/c-5p directly targets the RAD51 mRNA 3′-UTR or indirectly inhibits RAD51 expression via the p53 signaling pathway. Taken together, our results indicate that miR-34s overexpression depresses the efficiency of HR repair and induces DSBs by downregulating RAD51 expression. Our findings highlight a novel mechanism of HR pathway regulation via the miR-34s/p53/RAD51 axis.
•MiR-34s increase DSB accumulation in multiple cell lines.•MiR-34s suppress the efficiency of HR repair.•MiR-34s downregulate RAD51 at the mRNA and protein levels.•We show a novel mechanism of HR pathway regulation via the miR-34s/p53/RAD51 axis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
By means of density functional theory, the ammonia decomposition reactions catalyzed by Ni.sub.13, Cu.sub.13, and Ni.sub.12Cu clusters have been studied and compared. We firstly investigated the ...structural stability of these clusters, and then systematically investigated their ammonia decomposition activity by analyzing the adsorption property of reaction intermediates and the relative energy diagram. The results show that the adsorption energy of reaction intermediate N on Ni.sub.12Cu cluster is -5.93 eV, which is very close to the optimal value (-5.81 eV) of ammonia decomposition volcano curve. The reaction energy diagram shows that the dehydrogenation of NH intermediate is the rate-determining step for these clusters due to the positive reaction heat. Furthermore, the catalytic property of Ni.sub.12Cu cluster is interpreted by density of states. It indicates that the adsorption energies of reaction intermediates mainly depend on the d-band center of the clusters.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
To reduce the use of precious metals and maintain the catalytic activity for NH
3
decomposition reaction, it is an effective way to construct bimetallic nanoparticles with special structures. In this ...paper, by using density functional theory methods, we investigated NH
3
decomposition reaction on three types of core−shell nanoparticles M@Ni (M = Fe, Ru, Ir) with 13 core M atoms and 42 shell Ni atoms. The size of these three particles is about 1 nm. Benefit from alloying with Ru in this nanocluster, Ru@Ni core−shell nanoparticles exhibit catalytic activity comparable to that of single metal Ru, based on the analysis of the adsorption energy and potential energy diagram of NH
3
decomposition, as well as N
2
desorption processes. However, as for Fe@Ni and Ir@Ni core−shell nanoparticles, their catalytic activities are still unsatisfactory compared to the active metal Ru. In addition, in order to further explain the synergistic effect of bimetallic core−shell nanoparticles, the partial density of states were also calculated. The results show that d-band electrons provided by the core metal are the main factors affecting the entire catalytic process.
A percentage of colorectal cancer (CRC) patients display low sensitivity to radiotherapy, which affects its therapeutic effect. Cancer cells DNA double-strand breaks (DSBs) repair capacity is crucial ...for radiosensitivity, but the roles of long noncoding RNAs (lncRNAs) in this process are largely uncharacterized. This study aims to explore whether
lnc-RI
regulates CRC cell growth and radiosensitivity by regulating the nonhomologous end-joining (NHEJ) repair pathway. CRC cells in which
lnc-RI
has been silenced showed lower cell growth and higher apoptosis rates due to increased DSBs and cell cycle arrest. We found that miR-4727-5p targets both
lnc-RI
and
LIG4
mRNA and inhibit their expression. CRC cells showed increased radiosensitivity when
lnc-RI
was silenced. These results reveal novel roles for
lnc-RI
in both DNA damage repair and radiosensitivity regulation in CRC cells. Our study revealed that
lnc-R
I regulates
LIG4
expression through
lnc-RI
/miR-4727-5p/
LIG4
axis and regulates NHEJ repair efficiency to participate in DNA damage repair. The level of
lnc-RI
was negatively correlated with the radiosensitivity of CRC cells, indicates that
lnc-RI
may be a potential target for CRC therapy. We also present the first report of the function of miR-4727-5p.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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