Excimer laser crystallization of microcrystalline silicon for TFTs on flexible substrate

Microcrystalline silicon (μc-Si) films have been deposited on PDMS as well as on PEN substrate. Excimer laser annealing was used to improve the crystalline structure and so to obtain high mobility TFTs. The effect of the laser annealing on the crystalline structure of silicon films is studied using different characterization techniques and discussed. Mobility values of 60 cm²/V s with PDMS and 46 cm²/V s with PEN are obtained.     

Synthesis optimization of organic xerogels produced from convective air-drying of resorcinol-formaldehyde gels

Resorcinol-formaldehyde gels were produced at 50, 70 and 90 °C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied in order to optimize the synthesis conditions. The convective air-drying process was used, and the drying duration was studied with regard to the synthesis conditions. The aging time has no effect on the pore texture after 24 h at 90 °C or 48 h at 70 °C, whatever the R/C value. The synthesis-aging step can be shortened by increasing the temperature. Nevertheless, the pore size tends then to decrease, especially when R/C is high, but this can be counterbalanced by increasing R/C. Moreover, bubbles often appear in the gel at high synthesis temperature, which limits the temperature to about 70 °C in the case of monolithic parts. At 70 °C and with an air velocity of 2 m/s, the elimination of 90% of the solvent requires 1 h drying when the pore size reaches 400-600 nm, 2.5 h for 50 nm wide pores and 3 h when the pore size decreases to 15-20 nm. The drying duration does not exceed 8 h in all cases and could be shortened by increasing the temperature at the end of the process.     

1,5‐Asymmetric induction during nucleophilic additions to arenetricarbonylchromium complexes: tricarbonyl(η6‐1‐methyl‐4‐{spiro[(1R,2S)‐1,7,7‐trimethylbicyclo[2.2.1]heptane‐3,2′‐1,3‐dioxolan]‐2‐yloxy}benzene)chromium

The tricarbonylchromium unit bound to the arene ring of the chiral title complex, [Cr(C₁₉H₂₆O₃)(CO)₃], is rotated by ca 25° in agreement with the proposed mechanism for 1,5‐asymmetric induction of nucleophilic attack.     

Synthesis of hydroxycinnamic acid glucuronides and investigation of their affinity for human serum albumin

Hydroxycinnamic acids (HCAs) are among the most abundant dietary polyphenols. Recent bioavailability studies have shown that HCAs enter the blood circulation mainly as glucuronides, which are thus most likely to express their potential health effects. In this work, an efficient synthesis of HCA O-arylglucuronides is developed. As for many xenobiotics, the resilience of HCA O-arylglucuronides in plasma and subsequent delivery to tissues could be governed by their binding to human serum albumin (HSA). Hence, the affinity of HCA O-arylglucuronides for HSA and its possible binding site were investigated by fluorescence spectroscopy. HCA O-arylglucuronides turn out to be moderate HSA ligands (K in the range 1-4 x 10(4) M(-1)) that bind HSA in sub-domain IIA, competitively or noncompetitively with other sub-domain IIA ligands such as dansylamide and the flavonol quercetin.     

Electrokinetic-based injection modes for separative microsystems

Miniaturization of analytical instruments has attracted a wide interest in Analytical Chemistry over the past decade because of the advantages such as reduced reagent consumption and shorter analysis time. For chips involving separation, injection is a key step to achieve efficient and sensitive analysis. Electrokinetic injection mode is mostly used in chips because it is easier to generate flow motion in microsystems via electric potential control at channel extremities than pressure-driven flow. The injection step usually involves several intersecting channels. For each injection design, different injection modes can be done, depending on electric field sequences and distributions. This paper is an up-to-date review of these different modes on a chip.     

Oxidative coupling of acridinones: Synthesis of new C2‐symmetry atropisomers

The preparation of symmetric 2,2′‐dimethoxy‐10,10′‐biacridinyl‐9,9′‐dione atropisomers were obtained by the oxidative coupling of 9(10H)‐acridinone with 1,3‐dibromo‐5,5‐dimethyl‐imidazolidine‐2,4‐dione     

Clustering Six Electrons within “Dawson-Like” Polyoxometalate: An Open Route toward Its Post-functionalization

Super-reduction of polyoxometalates (POMs) in solution is of fundamental interest for designing innovative energy storage systems. In this article, we show that the “Dawson-like” POM can undergo a disproportionation process during its massive electron uptake, leading to species containing three metal-metal bonds as evidenced by X-ray diffraction, multi-nuclear magnetic resonance spectroscopy (¹H and ¹⁸³W NMR), extended X-ray absorption fine structure (EXAFS), UV/Vis, and voltammetry techniques. This result indicates that electron storing within metal-metal bonds is not a unique property of Keggin-type POM as postulated since the 70s. Besides, we demonstrate that the presence of an electron-rich triad in the “Dawson-like” POM allows its post-functionalization with additional tungstate ions, generating a chiral molecule that is also the largest W^IV-containing POMs known to date.     

Electrochromatographic separation on a poly(dimethylsiloxane)/glass chip by integration of a capillary containing an acrylate monolithic stationary phase

In this paper, we present an approach to perform electrochromatographic separations on poly(dimethylsiloxane) chips: a fused-silica capillary containing a stationary phase was introduced directly into the chip. This approach would offer great flexibility since capillary modification methods are well known, and thus, with this kind of chip, different microfluidic devices having various functions could be prepared. Electrophoretic separations were first achieved by integrating an empty capillary into the chip to evaluate the analytical performances of this system. They were compared to those obtained with a classical chip. Finally, an electrochromatographic separation involving a capillary containing a hexyl acrylate-based monolith was performed. These preliminary results show this approach to be promising.