Interfacial propulsion by directional adhesion

The rough integument of water-walking arthropods is well-known to be responsible for their water-repellency [1], [2], [3] and [4]; however, water-repellent surfaces generally experience reduced traction at an air-water interface [5], [6], [7] and [8]. A conundrum then arises as to how such creatures generate significant propulsive forces while retaining their water-repellency. We here demonstrate through a series of experiments that they do so by virtue of the detailed form of their integument; specifically, their tilted, flexible hairs interact with the free surface to generate directionally anisotropic adhesive forces that facilitate locomotion. We thus provide new rationale for the fundamental topological difference in the roughness on plants and water-walking arthropods, and suggest new directions for the design and fabrication of unidirectional superhydrophobic surfaces.     

Electron Spin Resonance and Ground State Wave Functions of Vanadyl Ion in LiNaSO<Subscript>4</Subscript>

Electron spin resonance (ESR) of VO²⁺ doped into LiNaSO₄ has been studied at 300 K on an X-band spectrometer. The ESR powder spectra have been analyzed and spin Hamiltonian parameters have been evaluated. Using the crystal-field approach, a theoretical estimate of the ground state wave functions of VO²⁺ in LiMSO₄ (M = Na, K) has been made from the ESR data. The dipolar hyperfine coupling constant P and Fermi contact parameter K have also been estimated.     

Rhodium-Catalyzed Copper-Assisted Intermolecular Domino C−H Annulation of 1,3-Diynes with Picolinamides: Access to Pentacyclic π-Extended Systems

A new mode of reactivity of 1,3-diynes in rhodium-catalyzed oxidative annulation reactions has enabled the rapid assembly of extended π systems from readily available picolinamide derivatives. The process involves a double C−H bond activation and the iterative annulation of two 1,3-diyne units, with each alkyne moiety engaged in an orchestrated insertion sequence with high regiocontrol, leading to the formation of five new C−C bonds and the construction of four fused rings in a single operation. Either isoquinoline-1-carboxamides or fused polycyclic systems can be accessed by a switch in the regioselectivity of the second diyne insertion depending on the reaction conditions. DFT theoretical calculations have elucidated that the cooperative participation of both rhodium and copper in substrate activation, favored in the presence of excess of the copper(II) salt, is key to such a reversal of regioselectivity and subsequent multiple cyclization leading to fused polycyclic products. The role of copper was found to be essential in assisting both multiple insertion and rhodium-walking sequences, with the implication of intermediates with a Rh−Cu bond (2.60 Å).     

Chaotic oscillations in a piecewise linear spring-mass system

Chaotic oscillations are useful in assessing the health of a structure. Hence, simple chaotic systems which can easily be realized mechanically or electro-mechanically are highly desired. We study a new piecewise linear spring-mass system. The chaotic behaviour in this system is characterized using bifurcation diagrams and the invariant parameters of the dynamics. We also show that there exists a stochastic analogue of this system, which mimics the dynamical features of its deterministic counterpart. This allows a greater flexibility in practical designs as the chaotic oscillations are obtained either deterministically or stochastically. Also, the oscillations are low dimensional, which reduces the computational resources needed for obtaining the invariant parameters of this system.     

NLOphoric Triphenylamine Derived Donor‐π‐Acceptor‐π‐Donor Based Colorants: Synthesis,Spectroscopic, Density Functional Theory and Z‐scan Studies

Three Donor‐π‐Acceptor‐π‐Donor type styryl dyes ( 5a‐c ) with different secondary donors are synthesized and characterized to study their nonlinear and linear optical properties. The structure–property relationships of the dyes are described in the light of systematic photophysical and theoretical investigations. The photophysical characteristics of 5a‐c are influenced by the polarity of the medium, with an appreciable bathochromic shift in emission ( 5b = 81 nm) and large Stoke shifts ( 5b = 104–173 nm) in polar solvents. 5a‐c showed intramolecular charge transfer characteristics recognized with the help of emission solvatochromism, solvent polarity graphs, natural bond orbital analysis and HOMO–LUMO energy difference. The optimized geometry and frontier molecular orbitals reveal that the electron donation takes place from secondary donors and not from a fixed donor (triphenylamine) which is more twisted. The nonlinear optical properties obtained using solvent induced spectral shift and computational methods are found within the limiting values. Z‐scan results reveal saturable kind of behavior for 5a , 5b and 5c , whereas 5a and 5b show reverse saturable kind of behavior in acetone and ethanol and hence give optical limiting values. The two‐photon absorption cross section described by two‐level approximation is highest for 5b (251–300 GM).     

Elastic scattering of 1.17 and 1.33 MeV gamma rays by molybdenum,tantalum and lead

Elastic scattering cross-sections of lead, tantalum and molybdenum were determined with the help of a Ge (Li) detector for 1.17 and 1.33 MeV rays between 30° and 115°. Theoretical evaluations of the cross-sections are based on a coherent addition of the well-known nuclear Thomson scattering amplitudes, the Rayleigh amplitudes calculated by Kissel and Pratt and the Delbrück amplitudes given by Papatzacos and Mork. The fairly good agreement between experiment and theory reveals the importance of the real Delbrück amplitudes. However, the experimental results in the 30–60° range tend to lie slightly but systematically below the calculated cross-sections. Work supported in part by a grant from the National Bureau of Standards, Washington, DC under the SFCP programme.     

Hyperelliptic Curves Describing Coulomb Phase of N = 2 Supersymmetric Theories with Classical Gauge Groups SU(3) and SO(6)

Breaking N = 2 SU(3) and N =2 SO(6) supersymmetric Yang–Mills theoriesto corresponding N = 1 theories by suitable tree-levelsuperpotentials, thehyperelliptic curves describing the Coulomb phase of these theories have beenobtained and it has been shown that the mass gap in the N = 1confining phaseof these theories vanishes when N = 1 parameters are properlytuned to approachthe highest critical points.     

Viscosity,Ultrasonic, and Refractometric Studies of Chitosan/Polyethylene Glycol Blend in Solution at 30, 40, and 50°C

Measurements of viscosity, ultrasonic velocity, refractive index, and density of chitosan (CS)/polyethylene glycol (PEG) blends in buffer solution (0.1 M acetic acid+0.2 M sodium acetate) were carried out for different blend compositions at 30, 40, and 50°C. Using the viscosity data, interaction parameters μ and α were computed to determine miscibility. These values revealed that the blend was miscible when the chitosan content was more than 60% of the blend. The results were further confirmed by ultrasonic velocity, density, and refractive index measurements. Further, the results revealed that the change in temperature has no significant effect on the miscibility of CS/PEG polymer blends.     

Pattern Classifications Using Grover’s and Ventura’s Algorithms in a Two-qubits System

Carrying out the classification of patterns in a two-qubit system by separately using Grover’s and Ventura’s algorithms on different possible superposition, it has been shown that the exclusion superposition and the phase-invariance superposition are the most suitable search states obtained from two-pattern start-states and one-pattern start-states, respectively, for the simultaneous classifications of patterns. The higher effectiveness of Grover’s algorithm for large search states has been verified but the higher effectiveness of Ventura’s algorithm for smaller data base has been contradicted in two-qubit systems and it has been demonstrated that the unknown patterns (not present in the concerned data-base) are classified more efficiently than the known ones (present in the data-base) in both the algorithms. It has also been demonstrated that different states of Singh-Rajput MES obtained from the corresponding self-single- pattern start states are the most suitable search states for the classification of patterns |00>,|01 >, |10> and |11> respectively on the second iteration of Grover’s method or the first operation of Ventura’s algorithm.