Inverse dynamics of the HALF parallel manipulator with revolute actuators

Recursive matrix relations for kinematics and dynamics of the HALF parallel manipulator are presented in this paper. The prototype of this robot is a spatial mechanism with revolute actuators, which has two translation degrees of freedom and one rotation degree of freedom. The parallel manipulator consists of a base plate, a movable platform and a system of three connecting legs, having wide application in the fields of industrial robots, simulators, parallel machine tools and any other manipulating devices where high mobility is required. Supposing that the position and the motion of the moving platform are known, an inverse dynamics problem is solved using the principle of virtual powers. Finally, some iterative matrix relations and graphs of the torques and powers for all actuators are analysed and determined. It is shown that this approach is an effective means for kinematics and dynamics modelling of parallel mechanisms.     

Chebyshev splines and shape parameters

A parametric spline curve is defined whose restriction to each sub-interval belongs to a 4-dimensional piecewise Chebyshev subspace depending on coefficients which play the role of shape parameters. This revised version was published online in August 2006 with corrections to the Cover Date.     

A multiplicity theorem for hemivariational inequalities with a p -Laplacian-like differential operator

We consider a parametric nonlinear elliptic inclusion with a multivalued p$p$-Laplacian-like differential operator and a nonsmooth potential (hemivariational inequality). Using a variational approach based on the nonsmooth critical point theory, we show that for all the values of the parameter in an open half-line, the problem admits at least two nontrivial solutions. Our result extends a recent one by Kristály, Lisei, and Varga [A. Kristály, H. Lisei, C. Varga, Multiple solutions for p$p$-Laplacian type operator, Nonlinear Anal. 68 (5) (2008) 1375–1381].     

Bernstein-type operators on a triangle with all curved sides

We construct and analyze Bernstein-type operators on triangles with curved sides, their product and Boolean sum. We study the interpolation properties and approximation accuracy. Using the modulus of continuity we also study the remainders of the corresponding approximation formulas. Finally, there are given some particular cases and numerical examples.     

Structural organization of plasma membrane lipids isolated from cells cultured as a monolayer and in tissue-like conditions

In this paper, folate conjugated poly(ε-caprolactone-co-4-maleate-ε-caprolactone) (P(CL-co-MCL)-folate) was prepared by a carbodiimide coupling reaction, i.e., the vitamin folic acid (FA) was covalently linked to the main chain of the maleate-functionalized polymer, poly(ε-caprolactone-co-4-maleate-ε-caprolactone) (P(CL-co-MCL)). Then the 5-Fluorouracil (5-FU) loaded nanoparticles of P(CL-co-MCL)-folate were achieved by solvent-evaporation method. Their properties were extensively studied by dynamic light scattering (DLS) and scan electron microscopy (SEM). DLS and SEM showed that the nanoparticles were in a well-defined spherical shape with a uniform size distribution. We also investigated the entrapment and in vitro release behavior, which indicated that the release speed of 5-FU could be well controlled and the release half-life period could reach 16.86h, which was 26.4 times longer than that of pure 5-FU. The in vitro targeting test displayed that the 5-FU loaded P(CL-co-MCL)-folate nanoparticles exhibited an enhanced cell inhibition because folate targeting increased the concentration of 5-FU loaded P(CL-co-MCL)-folate nanoparticles in the tumor cells with folate receptor overexpressed. Meanwhile, the tumor inhibition of 5-FU loaded P(CL-co-MCL)-folate nanoparticles was much higher than that of pure 5-FU and that of 5-FU loaded P(CL-co-MCL) nanoparticles. Therefore, P(CL-co-MCL)-folate nanoparticles would be highly beneficial for biomedical and pharmaceutical applications.     

Nonequilibrium phases of nanoparticle Langmuir films

We report on an in-situ observation of the colloidal silver nanoparticle self-assembly into a close-packed monolayer at the air/water interface followed by a 2D to 3D transition. Using the fast tracking GISAXS technique, we were able to observe the immediate response to the compression of the self-assembled nanoparticle layer at the air/water interface and to identify all relevant intermediate stages including those far from the equilibrium. In particular, a new nonequilibrium phase before the monolayer collapse via the 2D to 3D transition was found that is inaccessible by the competing direct space imaging techniques such as the scanning and transmission electron microscopies due to the high water vapor pressure and surface tension.     

Design, preparation, and study of catalytic gated baskets

We report a diastereoselective synthetic method to obtain a family of catalytic molecular baskets containing a spacious cavity (~570 ?(3)). These supramolecular catalysts were envisioned, via the process of gating, to control the access of substrates to the embedded catalytic center and thereby modulate the outcome of chemical reactions. In particular, gated basket 1 comprises a porphyrin "floor" fused to four phthalimide "side walls" each carrying a revolving aromatic "gate". With the assistance of (1)H NMR and UV-vis spectroscopy, we demonstrated that the small 1-methylimidazole guest (12, 94 ?(3)) would coordinate to the interior while the larger 1,5-diadamantylimidazole guest (14, 361 ?(3)) is relegated to the exterior of basket Zn(II)-1. Subsequently, we examined the epoxidation of differently sized and shaped alkenes 18-21 with catalytic baskets 12(in)-Mn(III)-1 and 14(out)-Mn(III)-1 in the presence of the sacrificial oxidant iodosylarene. The epoxidation of cis-stilbene occurred in the cavity of 14(out)-Mn(III)-1 and at the outer face of 12(in)-Mn(III)-1 with the stereoselectivity of the two transformations being somewhat different. Importantly, catalytic basket 14(out)-Mn(III)-1 was capable of kinetically resolving an equimolar mixture of cis-2-octene 20 and cis-cyclooctene 21 via promotion of the transformation in its cavity.     

On p-superlinear equations with a nonhomogeneous differential operator

We consider a nonlinear elliptic equation driven by a nonhomogeneous differential operator and with a (p?1)-superlinear Carathéodory reaction. Our formulation incorporates as a special case equations monitored by the p-Laplacian. Using variational methods coupled with truncation techniques and comparison principles, we show that the problem has at least five nontrivial smooth solutions.     

Bernstein-type Operators on a Triangle with One Curved Side

We construct Bernstein-type operators on a triangle with one curved side. We study univariate operators, their product and Boolean sum, as well as their interpolation properties, the order of accuracy (degree of exactness, precision set) and the remainder of the corresponding approximation formulas. We also give some illustrative examples.     

Nanostructured Au/Si substrate for organic molecule SERS detection

Nanoparticles of noble metals, such as gold and silver, exhibit unique and tunable optical properties on account of their surface plasmon resonance. In particular, gold nanoparticles on silicon substrates are attractive for future nanoscale sensors and optical devices due to their resistance to oxidation and due to their electrical and optical properties. In this study, we developed a nanostructured gold/macroporous silicon (Au/PS) substrate capped with 11-mercaptoundecanoic acid (11-MUA) with ultra-sensitive detection properties achieved in characterization, an approach based on surface-enhanced Raman scattering (SERS). Surface-enhanced Raman scattering allows us to detect substances at a low concentration level and to observe structural details of a thiol molecule bonded to small film thicknesses. Raman measurements were carried out at 514 nm and 785 nm. In order to emphasize the effect of the Si microstructuration on the efficiency of this new substrate (Au/PS) proposed for SERS experiments, the same molecule (11-MUA) was adsorbed on it as well as on gold/atomically flat silicon (Au/Si) and on commercial Klarite (Mesophotonics) substrates. Systematic studies realized by Raman spectroscopy, electron microscopy, and X-ray spectroscopy show the influence of silicon substrate texturing and metallic deposition conditions, including time and temperature on the optical phenomena.