Partitioned Method of Insect Flapping Flight for Maneuvering Analysis

This study proposed a partitioned method to analyze maneuvering of insects during flapping flight. This method decomposed the insect flapping flight into wing and body subsystems and then coupled them via boundary conditions imposed on the wing’s base using one-way coupling. In the wing subsystem, the strong coupling of the flexible wings and surrounding fluid was accurately analyzed using the finite element method to obtain the thrust forces acting on the insect’s body. The resulting thrust forces were passed from the wing subsystem to the body subsystem, and then rigid body motion was analyzed in the body subsystem. The rolling, yawing, and pitching motions were simulated using the proposed method as follows: In the rolling simulation, the difference of the stroke angle between the right and left wings caused a roll torque. In the yawing simulation, the initial feathering angle in the right wing only caused a yaw torque. In the pitching simulation, the difference between the front- and back-stroke angles in both the right and left wings caused a pitch torque. All three torques generated maneuvering motion comparable with that obtained in actual observations of insect flight. These results demonstrate that the proposed method can adequately simulate the fundamental maneuvers of insect flapping flight. In the present simulations, the maneuvering mechanisms were investigated at the governing equation level, which might be difficult using other approaches. Therefore, the proposed method will contribute to revealing the underlying insect flight mechanisms

Computational Fluid-Structure Interaction Framework for Simulating Characteristic Deformations in Insect Flapping Wings

In this study, a computational fluid­structure interaction (FSI) framework for characteristic deformations in insect's wings is proposed. The proposed framework consists of a pixel wing model using a structured shell finite element mesh, a projection method for the monolithic FSI monolithic equations using an algebraic splitting, and the FSI dynamic similarity law to measure dynamic similarity between model's and actual insect's flights. It is shown that the proposed framework can directly simulate passive feathering and cambering in insect's wings caused by the FSI, whose magnitudes are very close to those of actual insects

Pseudoelastic mesh–moving using a general scenario of the selective mesh stiffening

The selective mesh stiffening in this study changes the stiffness of the element based on both the element area and shape. It includes the stiffening in the previous studies as a specific case, and leads to a general scenario in the pseudoelastic mesh–moving. This scenario gives better mesh quality in the mesh-moving of a rectangular domain with a structure consisting of a square and a fin undergoes large rotations. This is because the shear deformation of the element is adaptively considered

Imaging chemical reactions one molecule at a time

In this article, we focus on demonstrating the utility of scanning probe methods in the imaging of chemical reactions. We first highlight the utility of different imaging methods and highlight their advantages and drawbacks. Subsequently, we select a number of examples to illustrate different surface processes including adsorption, dissociation, diffusion and rotation of adsorbed molecules, formation of reaction intermediates, and conclude with complex reactions. In these examples, we mainly focus on the STM, which is most extensively employed as a method of choice. To limit the complexity of the article we have selected only a few systems for the discussion. In particular, elemental steps in the reactions of water, alcohols, and diols on TiO2(110) surface are utilized to illustrate the power of imaging techniques in our understanding of surface chemistry. We also provide a brief outlook on both current and future challenges in this exciting area of research

Quasiparticle interfacial level alignment of highly hybridized frontier levels: H2_2O on TiO2_2(110)

Knowledge of the frontier levels' alignment prior to photo-irradiation is necessary to achieve a complete quantitative description of H$_2$O photocatalysis on TiO$_2$(110). Although H$_2$O on rutile TiO$_2$(110) has been thoroughly studied both experimentally and theoretically, a quantitative value for the energy of the highest H$_2$O occupied levels is still lacking. For experiment, this is due to the H$_2$O levels being obscured by hybridization with TiO$_2$(110) levels in the difference spectra obtained via ultraviolet photoemission spectroscopy (UPS). For theory, this is due to inherent difficulties in properly describing many-body effects at the H$_2$O-TiO$_2$(110) interface. Using the projected density of states (DOS) from state-of-the-art quasiparticle (QP) $G_0W_0$, we disentangle the adsorbate and surface contributions to the complex UPS spectra of H$_2$O on TiO$_2$(110). We perform this separation as a function of H$_2$O coverage and dissociation on stoichiometric and reduced surfaces. Due to hybridization with the TiO$_2$(110) surface, the H$_2$O 3a$_1$ and 1b$_1$ levels are broadened into several peaks between 5 and 1 eV below the TiO$_2$(110) valence band maximum (VBM). These peaks have both intermolecular and interfacial bonding and antibonding character. We find the highest occupied levels of H$_2$O adsorbed intact and dissociated on stoichiometric TiO$_2$(110) are 1.1 and 0.9 eV below the VBM. We also find a similar energy of 1.1 eV for the highest occupied levels of H$_2$O when adsorbed dissociatively on a bridging O vacancy of the reduced surface. In both cases, these energies are significantly higher (by 0.6 to 2.6 eV) than those estimated from UPS difference spectra, which are inconclusive in this energy region. Finally, we apply self-consistent QP$GW$ (scQP$GW$1) to obtain the ionization potential of the H$_2$O-TiO$_2$(110) interface.Comment: 12 pages, 12 figures, 1 tabl

Interface structure between tetraglyme and graphite

Clarification of the details of the interface structure between liquids and solids is crucial for understanding the fundamental processes of physical functions. Herein, we investigate the structure of the interface between tetraglyme and graphite and propose a model for the interface structure based on the observation of frequency-modulation atomic force microscopy in liquids. The ordering and distorted adsorption of tetraglyme on graphite were observed. It is found that tetraglyme stably adsorbs on graphite. Density functional theory calculations supported the adsorption structure. In the liquid phase, there is a layered structure of the molecular distribution with an average distance of 0.60 nm between layers

Characterization of MATE-Type Multidrug Efflux Pumps from <i>Klebsiella pneumoniae</i> MGH78578

<div><p>We previously described the cloning of genes related to drug resistance from <i>Klebsiella pneumoniae</i> MGH78578. Of these, we identified a putative gene encoding a MATE-type multidrug efflux pump, and named it <i>ketM</i>. <i>Escherichia coli</i> KAM32 possessing <i>ketM</i> on a plasmid showed increased minimum inhibitory concentrations for norfloxacin, ciprofloxacin, cefotaxime, acriflavine, Hoechst 33342, and 4',6-diamidino-2-phenyl indole (DAPI). The active efflux of DAPI was observed in <i>E</i>. <i>coli</i> KAM32 possessing <i>ketM</i> on a plasmid. The expression of mRNA for <i>ketM</i> was observed in <i>K</i>. <i>pneumoniae</i> cells, and we subsequently disrupted <i>ketM</i> in <i>K</i>. <i>pneumoniae</i> ATCC10031. However, no significant changes were observed in drug resistance levels between the parental strain ATCC10031 and <i>ketM</i> disruptant, SKYM. Therefore, we concluded that KetM was a multidrug efflux pump, that did not significantly contribute to intrinsic resistance to antimicrobial chemicals in <i>K</i>. <i>pneumoniae</i>. MATE-type transporters are considered to be secondary transporters; therefore, we investigated the coupling cations of KetM. DAPI efflux by KetM was observed when lactate was added to produce a proton motive force, indicating that KetM effluxed substrates using a proton motive force. However, the weak efflux of DAPI by KetM was also noted when NaCl was added to the assay mixture without lactate. This result suggests that KetM may utilize proton and sodium motive forces.</p></div