Spatial energy estimates in dynamical problems for a semi-infinite piezoelectric beam

The behaviour of the total energy for a semi-infinite piezoelectricbeam, with uniform or variable cross-section, in dynamical conditionsis investigated. Precisely, we obtain some estimates in termsof the data for the energy of the portion of the body at distancegreater than z from the base and for its norm in L¹(0,t) (wheret is an arbitrary positive time). We obtain some estimates whichdepend on the initial data if t z/V (where V is a computablepositive material constant); if t > z/V, by using also theKorn inequality, we show that the bounds depend on all the data.Under mild hypotheses on the initial data we derive the asymptoticbehaviour of the energy as z +. All possible combinations ofboundary conditions are examined and the kind of the estimateis formally the same for all the problems whether the beam isa cylinder or not.     

Interconversion of carbon sites in boat-chair-boat cyclodecane; conformations of chlorocyclodecane and cyclodecyl acetate

Interconversion of carbon sites in boat-chair-boat (BCB) cyclodecane occurs by way of the twist-boat-chair (TBC) conformation, which predicts that C-1 exchanges with C-4, etc. The previously obtained low-temperature 13C spectra could be matched by assuming (1,4) or (1,3) exchange, but not (1,2) exchange. A free-energy barrier of 5.54 kcal/mol was obtained for conversion of BCB to TBC at -137.4 degrees C. The major conformation of chlorocyclodecane and cyclodecyl acetate is assigned to the IIIe BCB.     

Recherche systématique des cations à l'échelle ultramicrochimique sur grains de résines échangeuses d'ions

Microchimica Acta - Nous présentons une nouvelle méthode d'analyse générale systématique inorganique, à l'échelle ultramicrochimique, qui consiste à...     

Spectral Polarimeters Based on Integrated Acousto-Optical Ti:LiNbO3 TE-TM Converters

An integrated Ti:LiNbO3 acousto-optical TE-TM converter followed by a polarizer was used to realize a wavelength-selective polarimeter. The stop-band attenuation was shown to increase to > 28 dB when more mode converters were integrated on a chip. Based on this experience, a four-stage demonstration unit was built, and polarimetric spectra as well as the time evolution of the state of polarization were measured. Finally, a simple optical spectrum analyzer is proposed.     

2-DE and MALDI-TOF-MS analysis of therapeutic fusion protein abatacept

2-DE and MALDI-TOF MS are useful techniques for the quality evaluation of medicinal products derived from recombinant DNA technology. The principal objective of this study has been to evaluate the suitability of 2-DE in combination with MALDI-TOF MS for the quality study of the therapeutic recombinant protein, abatacept. 1-DE SDS-PAGE, under reducing and nonreducing conditions, and 2-DE analysis were used for the assessment of M(r) , pI, and enzymatic deglycosylation efficiency of abatacept. 2-DE allowed the assessment of product identity, purity, charge heterogeneity, isoform pattern, and post-translational modifications. Furthermore, optimization of the deglycosylation procedure, charge heterogeneity, and sample preparation for the subsequent MALDI-TOF MS analysis has been addressed. PMF analysis allowed rapid identity confirmation of abatacept.     

Inkjet Printed Multi‐walled Carbon Nanotube Sensor for the Detection of Lead in Drinking Water

Electroanalytical methods can be used for the reliable detection of the toxic heavy metal lead in drinking water samples. Inkjet printed electrodes have potential for the rapid and affordable assessment of drinking water. Researchers have shown the electrochemical sensing applicability of inkjet printed electrodes. In this work, Pb²⁺ was detected using an inkjet printed multi‐walled carbon nanotube (IJP‐MW‐CNT) electrode with silver tracks printed underneath. The silver tracks provide the sensor with the conductivity needed for sensitive measurements. MW‐CNT were dispersed in water using bile salts as a surfactant to prepare the ink. The IJP‐MW‐CNT electrode was used as the working electrode with a platinum wire and Ag/AgCl as auxiliary and reference electrode, respectively. The electrodes performance was optimized in 0.1 M acetate buffer (pH=4.3) and had two linear ranges of 5 to 20 ppb (R²=0.99) with a sensitivity of 38 nA/ppb and 20 to 50 ppb (R²=0.98) with a sensitivity of 15 nA/ppb and a limit of detection (LOD) of 1.0 ppb for Pb²⁺. The analytical applicability of electrode was determined by constructing a calibration curve in an unaltered drinking water sample (i. e.) Cincinnati tap water with two linear ranges of 15 to 40 ppb (R²=0.99) with a sensitivity of 1.5 nA/ppb and 40 to 70 ppb (R²=0.99) with a sensitivity of 3.5 nA/ppb and a LOD of 1.0 ppb for Pb²⁺. Effects of copper and cadmium as potential interferents are reported.     

Neutral Hexacoordinate Tin(IV) Halide Complexes with 4,4'-Dimethy-2,2'-bipyridine

A series of three neutral, hexacoordinate tin(IV) complexes were synthesized by the reaction of 4,4'-dimethyl-2,2'-bipyridine (DMB) with SnX₄, X = Cl, Br, and I, as starting materials. The complexes (DMB)SnX₄ were characterized in solution by ¹H, ¹³C, and ¹¹⁹Sn NMR spectroscopy, and in the solid-state by ¹¹⁹Sn MAS NMR spectroscopy. In addition, single-crystal X-ray diffraction and elemental analysis were used to confirm the molecular structures. In these complexes, the tin atom adopts a distorted octahedral arrangement and the DMB acts as a bidentate N,N'-chelate ligand. Computational DFT methods were also employed to gain more insight into the nature of the bonding in these complexes, including the hypothetical complexes (DMB)SnX₄ (X = F, At). Additionally, the validity and reliability of the ¹¹⁹Sn NMR chemical shifts were examined. The calculated values were compared with the experimental signals and the effects of structure and solvent are discussed. Finally, all of the complexes (DMB)SnX₄ were successfully tested for the ring-opening polymerization (ROP) of bulk ε-caprolactone under non-dried and aerobic conditions as precatalyst.     

Triplet annihlation in pyrene-d10 doped fluorene

Triplet exciton concentration inferred from delayed fluorescence measurements of pyrene-d₁₀ doped fluorene crystals has been examined as a function of temperature in order to study the correlation between exciton density and electronic triplet spin lattice relaxation (T_ie). The results have indicated a poor correlation between the delayed fluorescence intensity and the electronic relaxation rate although a qualitative correlation exists between the growth of trap phosphorescence and relaxation rate.