11,970 research outputs found
Synthesis of Co(3)O(4) nanowire arrays supported on Ni foam for removal of volatile organic compounds
No full textCrystalline Co3O4 nanowire arrays freely supported on Ni foam are successfully synthesized using a template-free method. The effects of reaction time, concentration of reactants, and temperature on the morphology of the nanowires are studied. The results indicate that uniform Co3O4 nanowires could be synthesized at 90 degrees C, and a transformation of the samples' morphology from nanoparticles to nanowires to microrods is observed by controlling the concentration of the reactants. The well-ordered nanowires synthesized under the selected reaction conditions are composed of spinel Co3O4 with diameters of 500-580 nm and lengths of 6-8 microm. These nanowires show good catalytic activity for the ozone catalytic oxidation of toluene.Hui, K. N.; Yin, Cui-Lei; Hui, K. S.; Lee, J. Y.; Li, M.; Lee, S. K.; Tsui, K. L.; Chao, Christopher Y H; Kwong, C. W
Do anionic phospholipids serve as cofactors or second messengers for the regulation of activity of cloned ATP-sensitive K+ channels?
No full textThe regulation of ion channels by anionic phospholipids is currently very topical. An outstanding issue is whether phosphatidylinositol 4,5-diphosphate and related species act as true second messengers in signaling or behave in a manner analogous to an enzymatic cofactor. This question is especially pertinent regarding ATP-sensitive K+ channels in smooth muscle, for which there is substantial literature supporting inhibitory regulation by hormones. In this study, we have examined regulation of the potential cloned equivalents of the smooth muscle ATP-sensitive K+ channel (SUR2B/Kir6.1 and SUR2B/Kir6.2). We find that both can be inhibited via the G(q/11)-coupled muscarinic M3 receptor but that the pathways by which this occurs are different. Our data show that SUR2B/Kir6.1 is inhibited by protein kinase C and binds anionic phospholipids with high affinity, such that potential physiological fluctuations in their levels do not influence channel activity. In contrast, Kir6.2 is not regulated by protein kinase C but binds anionic phospholipids with low affinity. In this case, phosphatidylinositol 4,5-diphosphate and related species have the potential to act as second messengers in signaling. Thus, Kir6.1 and Kir6.2 are regulated by distinct inhibitory mechanisms
J(P)=1(+) ud(s)over-bar(s)over-bar tetraquark
No full textUsing the color-magnetic interaction Hamiltonian with SU(3) flavor symmetry breaking, we perform a schematic study of the masses of the J(P) = 1(+) tetraquarks in the antidecuplet representation. After diagonalizing the mass matrix, we find the ud (s) over bar (s) over bar tetraquark could lie as low as about 1350 MeV. It decays into (K+KK)-K-0 pi(0), K(+)K(+)pi(-), K(0)K(0)pi(+) via P-wave. The dual suppression from the not-so-big three-body phase space and P- wave decay barrier may render this exotic state rather narrow. Future experimental exclusion of this state will cast doubt on the validity of applying the simple color-magnetic Hamiltonian to the multiquark system.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)13ARTICLE1null7
Warped Dipole Completed, with a Tower of Higgs Bosons
No full textIn the context of warped extra-dimensional models which address both the Planck-weak- and flavor-hierarchies of the Standard Model (SM), it has been argued that certain observables can be calculated within the 5D effective field theory only with the Higgs field propagating in the bulk of the extra dimension, just like other SM fields. The related studies also suggested an interesting form of decoupling of the heavy Kaluza-Klein (KK) fermion states in the warped 5D SM in the limit where the profile of the SM Higgs approaches the IR brane. We demonstrate that a similar phenomenon occurs when we include the mandatory KK excitations of the SM Higgs in loop diagrams giving dipole operators for SM fermions, where the earlier work only considered the SM Higgs (zero mode). In particular, in the limit of a quasi IR-localized SM Higgs, the effect from summing over KK Higgs modes is unsuppressed (yet finite), in contrast to the naive expectation that KK Higgs modes decouple as their masses become large. In this case, a wide range of KK Higgs modes have quasi-degenerate masses and enhanced couplings to fermions relative to those of the SM Higgs, which contribute to the above remarkable result. In addition, we find that the total contribution from KK Higgs modes in general can be comparable to that from the SM Higgs alone. It is also interesting that KK Higgs couplings to KK fermions of the same chirality as the corresponding SM modes have an unsuppressed overall contribution, in contrast to the result from the earlier studies involving the SM Higgs. Our studies suggest that KK Higgs bosons are generally an indispensable part of the warped 5D SM, and their phenomenology such as signals at the LHC are worth further investigation.In the context of warped extra-dimensional models which address both the Planck-weak- and flavor-hierarchies of the Standard Model (SM), it has been argued that certain observables can be calculated within the 5D effective field theory only with the Higgs field propagating in the bulk of the extra dimension, just like other SM fields. The related studies also suggested an interesting form of decoupling of the heavy Kaluza-Klein (KK) fermion states in the warped 5D SM in the limit where the profile of the SM Higgs approaches the IR brane. We demonstrate that a similar phenomenon occurs when we include the mandatory KK excitations of the SM Higgs in loop diagrams giving dipole operators for SM fermions, where the earlier work only considered the SM Higgs (zero mode). In particular, in the limit of a quasi IR-localized SM Higgs, the effect from summing over KK Higgs modes is unsuppressed (yet finite), in contrast to the naive expectation that KK Higgs modes decouple as their masses become large. In this case, a wide range of KK Higgs modes have quasi-degenerate masses and enhanced couplings to fermions relative to those of the SM Higgs, which contribute to the above remarkable result. In addition, we find that the total contribution from KK Higgs modes in general can be comparable to that from the SM Higgs alone. It is also interesting that KK Higgs couplings to KK fermions of the same chirality as the corresponding SM modes have an unsuppressed overall contribution, in contrast to the result from the earlier studies involving the SM Higgs. Our studies suggest that KK Higgs bosons are generally an indispensable part of the warped 5D SM, and their phenomenology such as signals at the LHC are worth further investigation.In the context of warped extra-dimensional models which address both the Planck-weak- and flavor-hierarchies of the Standard Model (SM), it has been argued that certain observables can be calculated within the 5D effective field theory only with the Higgs field propagating in the bulk of the extra dimension, just like other SM fields. The related studies also suggested an interesting form of decoupling of the heavy Kaluza-Klein (KK) fermion states in the warped 5D SM in the limit where the profile of the SM Higgs approaches the IR brane. We demonstrate that a similar phenomenon occurs when we include the mandatory KK excitations of the SM Higgs in loop diagrams giving dipole operators for SM fermions, where the earlier work only considered the SM Higgs (zero mode). In particular, in the limit of a quasi IR-localized SM Higgs, the effect from summing over KK Higgs modes is unsuppressed (yet finite), in contrast to the naive expectation that KK Higgs modes decouple as their masses become large. In this case, a wide range of KK Higgs modes have quasi-degenerate masses and enhanced couplings to fermions relative to those of the SM Higgs, which contribute to the above remarkable result. In addition, we find that the total contribution from KK Higgs modes in general can be comparable to that from the SM Higgs alone. It is also interesting that KK Higgs couplings to KK fermions of the same chirality as the corresponding SM modes have an unsuppressed overall contribution, in contrast to the result from the earlier studies involving the SM Higgs. Our studies suggest that KK Higgs bosons are generally an indispensable part of the warped 5D SM, and their phenomenology such as signals at the LHC are worth further investigation
XAFS Study of CuI-Y and CuII-Y Interacting with CO and NO
No full textWe report a study of the local copper environment in CuI-Y prepared by gas phase reaction of H. Y with CuCl and in CuII-Y prepared by conventional ion exchange with aqueous cupric salt. For the CuI-Y sample, the effect of the interaction with CO and NO will also been reported. XANES, UV-Vis and IR (NO dosed at 77 K) techniques prove that the copper species in the prepared samples have the desired oxidation state. Reduction of CuI-Y with CO leads to the formation of small copper clusters well identified by EXAFS, XANES and UV-Vis spectroscopies, while interaction with NO partially oxydate CuI to CuII. For both as prepared CuI-Y and CuII-Y samples EXAFS does not observe first shell Cu-Cu bond lengths, so excluding the presence of "so called" Cu-dimers in zeolites prepared following our methods
Cross sections for the reactions e+e- →k+K-π+π- (π0), K+K-K+K- (π0), π+π-π+π- (π0), p p ̄ π+π- (π0) in the energy region between 3.773 and 4.600 GeV
No full textUsing the data samples collected in the energy range from 3.773 to 4.600 GeV with the BESIII detector at the BEPCII collider, we measure the dressed cross sections as a function of center-of-mass energy for e+e-→K+K-π+π-(π0), K+K-K+K-(π0), π+π-π+π-(π0), and pp ̄π+π-(π0). The cross sections for e+e-→K+K-K+K-π0, pp ̄π+π-(π0) are the first measurements. Cross sections for the other five channels are much more precise than previous results in this energy region. We also search for charmonium and charmonium-like resonances, such as the Y(4230), decaying into the same final states. We find evidence of the ψ(4040) decaying to π+π-π+π-π0 with a statistical significance of 3.6σ. Upper limits are provided for other decays since no clear signals are observed
Observation of the and a new structure in
No full textThe cross sections of at center-of-mass
energies from 4.127 to 4.600~GeV are measured based on 15.6 fb data
collected with the BESIII detector operating at the BEPCII storage ring. Two
resonant structures are observed in the line shape of the cross sections. The
mass and width of the first structure are measured to be
() MeV and ()~MeV, respectively. They
are consistent with those of the established . The second structure is
observed for the first time with a statistical significance greater than
8, denoted as . Its mass and width are determined to be
() MeV and () MeV, respectively. The
first presented uncertainties are statistical and the second ones are
systematic. The product of the electronic partial width with the decay
branching fraction is reported
Evolutionary parameter optimization of electro-injector models for common rail diesel engines
No full textOne of the major issues in innovative automotive engines is to reduce the energy consumption and pollutant emissions, at the same time, to guarantee a high level of performance indices. To this aim, common rail diesel engines can satisfy strict regulations by enhancing the model-based control of the injection process to increase the combustion efficiency. This paper presents a more accurate model for the electro-injector in common rail diesel engines. The model takes into account the mechanical deformation of relevant parts of the electro-injector and the non-linearity of the fuel flow. Model parameters are then optimized by an evolutionary strategy. Simulation shows that the optimized model can be helpful in predicting the real trend of the injected fuel flow rate when assisted with the experimental data, and in controlling the injection
A study on the reliability of consecutive k-Out-of-n: G systems based on Copula
No full textThe computation of reliability characteristics of a system that consists of dependent components is sometimes difficult especially when the type of dependence is not known. This article introduces the copula method to calculate the reliability of dependent consecutive k-out-of-n: G systems. The components in these systems are dependent on each other and the dependency may be either linear or nonlinear. The copula is a popular tool for modeling the dependence structure of data. It contains the information about the dependency structure of a vector of random variables and can capture nonlinear dependence. Based on the copula theory, the article analyzes the consecutive k-out-of-n: G systems and gets the reliability indexes. Finally, some numerical examples are presented to illustrate the results obtained in this article.Peer reviewe
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