Minimum Mixed Time–Energy Trajectory Planning of a Nonlinear Vehicle Subject to 2D Disturbances

Journal of Optimization Theory and Applications - The problem of a planar vehicle moving on a surface, such as aerial drones or small naval vessels, can be treated as a series of trajectory...     

Hydrophobicity Control in Adaptive Crystalline Assemblies

An amphiphile based on polyethylene glycol (PEG) polymer and two molecular moieties (perylene diimide and C₇ fluoroalkyl, PDI and C₇F) attached to its termini assembles into crystalline films with long‐range order. The films reversibly switch from crystalline to amorphous above the PEG melting temperature. The adaptive behavior stems from the responsiveness of the PEG domain and the robustness of the PDI and C₇F assemblies. The hydrophobicity of the film can be controlled by heating, resulting in switching from highly hydrophobic to superhydrophilic. The long‐range order, reversible crystallinity switching, and the temperature‐controlled wettability demonstrate the potential of block copolymer analogues based on simple polymeric/molecular hybrids.     

Probing the molecular interaction of chymotrypsin with organophosphorus compounds by 31P diffusion NMR in aqueous solutions

In the present study, we applied for the first time (31)P diffusion NMR to resolve different species obtained by the addition of organophosphorus compounds (OP) such as diisopropyl phosphorofluoridate (DFP) or 1-pyrenebutyl phosphorodichloridate (PBPDC) to alpha-chymotrypsin (Cht). (31)P diffusion NMR was used since the products of these reactions constitute a mixture of OP-covalent conjugates of the enzyme and OP-containing hydrolysis products that have noninformative (1)H NMR spectra. It was shown that the peak, attributed to the covalent native diisopropylphosphoryl-Cht (DIP-Cht) conjugate by chemical shift considerations, has a greater diffusion coefficient (D = (0.65 +/- 0.01) x 10(-5) cm(2) s(-1)) than expected from its molecular mass (approximately 25 kDa). This peak was therefore suggested to consist of at least two superimposed signals of diisopropyl phosphoryl (DIP) pools of high and low molecular weights that happen to have the same chemical shift. This conclusion was substantiated by the use of DMSO-d(6) that separated the overlapping signals. Diffusion measurements performed on the extensively dialyzed and unfolded DIP-Cht conjugate still resulted in a high diffusion coefficient ((0.30 +/- 0.05) x 10(-5) cm(2) s(-1)) relative to the assumed molecular mass. This observation was attributed to a dynamic dealkylation at the OP moiety (i.e., aging) that occurred during the relatively long diffusion measurements, where DIP-Cht was converted to the corresponding monoisopropyl phosphoryl Cht (MIP-Cht) conjugate. Homogeneous aged forms of OP-Cht were obtained by use of DFP and heat-induced dealkylation of DIP-Cht, and by PBPDC that provided the aged form via the hydrolysis of a P-Cl bond (PBP-Cht). The thermally stable aged conjugates enabled a reliable determination of the diffusion coefficients over several days of data acquisition, and the values found were (0.052 +/- 0.002) x 10(-5) cm(2) s(-1) and (0.054 +/-0.004) x 10(-5) cm(2) s(-1) for the MIP-Cht and the PBP-Cht adducts, respectively, values in the range expected for a species with a molecular weight of 25 kDa. The advantages and limitations of (31)P diffusion NMR in corroborating the type of species that prevail in such systems are briefly discussed.     

The azaquinone-methide elimination: comparison study of 1,6- and 1,4-eliminations under physiological conditions

The azaquinone-methide elimination is a powerful and efficient reaction useful for disassembly of spacers in prodrug systems. We and others have used the spacer-technique to develop dendritic and polymeric self-immolative molecular systems that can disassemble through a domino-like mechanism upon a stimulus event. In this report, we study the disassembly of a system that can disintegrate through para- and ortho-azaquinone-methide eliminations. The disassembly was evaluated with molecules that undergo single 1,6- or 1,4-elimination and with molecules that undergo double 1,6- and 1,4-elimination. The 1,6-elimination was slightly faster than the 1,4-elimination under physiological conditions. This study sheds light on the disassembly-behavior of prodrug systems.     

Polychromatic vectorial vortex formed by geometric phase elements

We propose the use of a geometric phase, obtained by spatial polarization state manipulations, for the formation of polychromatic vectorial vortices. Experimental demonstration is obtained by using Pancharatnam-Berry phase optical elements formed by a space-variant subwavelength grating etched on a GaAs wafer. We further demonstrate formation of scalar and unpolarized polychromatic vortices.     

A Bessel identity for the theta correspondence

We establish a spectral identity between global Bessel distributions with respect to generic cuspidal representations of an odd orthogonal group and the metaplectic cover of a symplectic group which are related by the theta correspondence. We also provide analogous local identities for square-integrable representations.     

On Homogeneous Standard Integral Table Algebras of Degree 4

In this paper we classify, up to exact isomorphism, the algebras in the title which contain a faithful element and in which every non-trivial table subset has dimension at least five.     

Collinear nondegenerate four-wave mixing by a three-level system

Four-wave mixing in the vicinity of a sodium doublet is reported. The three-level system allows collinear phase-matching. The FWM is resonantly enhanced by a high gain on the blue side of the D₁ transition.Present address: LROL, Physics Department, Laval University, Quebec, Canada, G1K 7P4To whom correspondence should be addressed     

Sono-activation of persulfate by Fe-expanded perlite catalyst for oxidative degradation of Orange G: synergy study,influence of parameters and phytotoxicity tests

Research on Chemical Intermediates - Iron-coated expanded perlite (Fe-EP) was prepared as a heterogeneous catalyst for activating persulfate (PS) to degrade Orange G (OG) under ultrasonic...