Nonlinear theory of forced surface waves in a circular basin

A nonlinear theory is developed to study surface waves excited by the prescribed horizontal oscillation of the side wall of a circular basin. It is assumed that the frequency of the forced oscillation is near either one of the resonance frequencies of the water in the basin or twice of it. A multiple-scale asymptotic expansion is constructed to derive an equation for the amplitude of an excited eigenmode and critical points of some parameters are found for primary and subharmonic resonance waves. Across these critical points the eigenmode amplitude increases abruptly but remains bounded except at certain values of the water radius to the depth ratio where internal resonance appears.     

Forced capillary-gravity waves in a circular basin

A linear theory is developed to study the forced capillary-gravity waves generated on water in a circular basin by the horizontal oscillations of its side wall. A Green's function method is used to construct a solution of the linearized equations subject to an edge condition at the contact line. The problem is reformulated in terms of an integral equation on the equilibrium free surface, and a uniqueness result is obtained by invoking the Fredholm's alternatives.     

Electric and elastic multipole defects in finite piezoelectric media

In this paper, a piezoelectric analogy theorem is proposed, in which a piezoelectric body is represented as being composed of two fictitious bodies, an elastic body and a rigid dielectric body. An electric and elastic multipole approach for the treatment of various defects (dislocation, inhomogeneity, …) in finite piezoelectric media is then developed. It is shown that the electric and elastic coupling effects, the boundary effects, and the defects may be considered uniformly as sources of permanent and induced electric and elastic multipoles.     

Active dielectric metasurface based on phase‐change medium

We propose all‐dielectric metasurfaces that can be actively re‐configured using the phase‐change material Ge₂Sb₂Te₅ (GST) alloy. With selectively controlled phase transitions on the composing GST elements, metasurfaces can be tailored to exhibit varied functionalities. Using phase‐change GST rod as the basic building block, we have modelled metamolecules with tunable optical response when phase change occurs on select constituent GST rods. Tunable gradient metasurfaces can be realized with variable supercell period consisting of different patterns of the GST rods in their amorphous and crystalline states. Simulation results indicate a range of functions can be delivered, including multilevel signal modulating, near‐field coupling of GST rods, and anomalous reflection angle controlling. This work opens up a new space in exploring active meta‐devices with broader applications that cannot be achieved in their passive counterparts with permanent properties once fabricated.

     

Stage-frit: A straightforward sub-2 μm nano-liquid chromatography column fabrication for proteomic analysis

In this work we demonstrated a facile method for the fabrication of C18 coordination polymer gel in a capillary, called stage-frit, which was efficiently applied to pack sub-2 μm C18 beads into the capillary by a high pressure bomb for the online separation of proteolytic peptides. The back pressure of the column with 10 cm × 75 μm i.d. is regularly lower than 170 bar at a flow rate of 300 nl/min, which could be operated on a common nanoLC system instead of nanoUPLC system due to the good permeability, low back pressure and high mechanical stress of the frit that will totally reduce the cost for the purchase of instrument. The stage-frit allows long-term continuous flow of the solvent and no significant beads loss or pressure instability was observed during the period. The repeatability of retention time for fifteen BSA tryptic peaks was found to be less than 1.08% (RSD) in six time nanoLC-ESI-MS/MS experiments. The average full width at half maximum (FWHM) of peptide peaks is 5.87 s. The sub-2 μm stage-frit nanoLC column showed better sensitivity than the commercial available for large scale proteomic analysis of total tissue proteins from human spleen. The number of identified peptides is approximately 0.4-fold and 0.2-fold higher than that obtained by utilizing commercial columns packed with 3 μm and 1.8 μm C18 materials, respectively. In the field of analytical chemistry, particularly the use of nanoLC systems, stage-frit nanoLC column offers a great potential for the separation of complex mixtures.     

Direct Synthesis of Chiral 3‐Arylsuccinimides by Rhodium‐Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids to Maleimides

Chiral rhodium catalysts comprising 2,5‐diaryl‐ substituted bicyclo[2.2.1]diene ligands L1 – L10 were utilized in the enantioselective 1,4‐addition reaction of arylboronic acids to N‐substituted maleimides. In the presence of 2.5 mol % of Rh^I/ L2 , enantioenriched conjugate addition adducts were isolated in 72–99 % yields with 86–98 % ee. This protocol offers a convenient method to access a variety of 3‐arylsuccinimides in a highly enantioselective manner. Maleimides with readily cleavable N‐protecting groups were tolerated enabling the synthesis of useful synthetic intermediates. Pyrrolidine 4 , a biologically active compound, and pyrrolidine 5 , an ent‐precursor to an HSD‐1 inhibitor, were synthesized to demonstrate the utility of this method.     

Synthesis of five-coordinate manganese(I) carbonyl complex [(CO)<Subscript>3</Subscript>Mn (-S,-Se-C<Subscript>6</Subscript>H<Subscript>3</Subscript>-4-Me)]<Superscript>−</Superscript>: influences of non-innocent ligand to the structure,reactivity and electrochemical property

Oxidative addition of Br₂ to [Mn(CO)₅]^? leads to the formation of [(CO)₄MnBr], followed by the ligand exchange of bromide to [S,Se-C₆H₃-4-Me] ₂ ^2? to form complex (CO)₃Mn (µ-? ⁴-SC₆H₃-4-(CH₃)Se-SeC₆H₃-4-(CH₃)S)Mn(CO)₃ (1). A new five-coordinate complex [(CO)₃Mn(-S,-Se-C₆H₃-4-CH₃)]^? (2) can be synthesized through two different routes: (a) oxidative addition of diselenide [HS,Se-C₆H₃-4-Me]₂ to the [Mn(CO)₅]^? followed by deprotonation and ligand dissociation to generate complex 2; (b) reduction of diselenide bonds of complex 1 by [BH₄]^? to produce 2. Drop-wise addition of HBF₄·OEt₂ at 0 °C results in the formation of complex 1. The X-ray analysis shows that complex 2 has relative short Mn–Se and Mn–S bond distances compare to the published structures of cis-[(CO)₄Mn(EPh)₂]^? (E = S and Se; Liaw et al. in J. Chin. Chem. Soc. 43:427–431, 1996; Liaw et al. in Inorg. Chem. 35:2530, 1996). Interestingly, exposure of the coordinated unsaturated complex 2 under CO_(g) atmosphere resulted in complex cis-[(CO)₄Mn(-S,-Se-C₆H₃-4-Me)]^? (3) being formed. After purging the solution of complex 3 with N₂, it was reconverted completely back to complex 2; this observation was characterized by FTIR. The cyclic voltammetry scan of complex 2 shows a quasi-reversible redox couple with E _1/2 = ?1.94 V and I _pa/I _pc = 0.68. Ligand [HS, Se-C₆H₃-4-CH₃]₂ and complexes 1 and 2 are all characterized by IR, UV–Vis, NMR, EA and X-ray single crystal diffraction.     

Thermomechanical behavior of underfill/solder mask/substrate interface under thermal cycling

With the increasing application of flip-chip technology in the microelectronics industry, the adhesion strength of interfaces in flip-chip microelectronic structures has become an important issue for manufacturing and operation. In this paper we present an experimental investigation of the adhesive strength of underfill material to solder mask coated FR-4 substrate under thermal cycling. The effects of the number of thermal cycles on interfacial strength were investigated by using the button shear test. The relationship between interfacial strength and the thickness of solder mask was also examined. Furthermore, the morphologies of fracture surfaces of the test specimens were analyzed by scanning electron microscopy. The results of this study show that the interfacial strength of the underfill/solder mask/substrate joint was significantly reduced by thermal fatigue. Finally, the degradation behavior and possible mechanisms were then determined on the basis of these observations.     

Transport with a Very Low Density Contrast in Hele–Shaw Cell and Porous Medium: Evolution of the Mixing Zone

The optimal concentration of a blue dye solution with 'tracer' properties, enabling a pollutant to be marked was determined by the use of numerical, theoretical and experimental approaches. Experimental investigations were performed on a transparent Hele–Shaw cell and the concentration distribution was analyzed using an optical technique based on dye light absorption properties. The injected optimal concentration was established thanks to a theoretical and experimental study carried out on the output signal dynamics. Using the same experimental conditions, numerical simulations were performed. The very good agreement between the data (experimental and numerical) clarified that: (i) the choice of the blue dye optimal concentration was valid and (ii) the concentration-dependent density should not be neglected in flow and transport equations even if it concerns a so-called 'tracer'. Following this remark, a theoretical aspect was developed in order to determine the analogous conditions between a Hele–Shaw cell and a porous medium for the variable density transport phenomenon. The structure of the concentration-dependent dispersion tensor used in the numerical code was obtained by homogenizing the Stokes flow of a bi-component mixture. The numerical results show that, as long as the tracer density does not exceed a certain value, it is not necessary to take into account a density contrast in terms of the dispersion tensor. The classical form of the Taylor dispersion tensor can be used successfully.     

On damping coefficient due to phase transformation

The damping coefficient of capillary waves due to the evaporation-condensation process at the interface of the two phases of a fluid is evaluated. To highlight the mechanism of the effect of heat and mass transfer across the interface between regions of liquid and vapor, potential flow of incompressible fluids are assumed. Thus other mechanisms of damping are neglected. To fascilitate the analysis, the method of multiple-scale is employed in the analysis, even though the problem is linear.