Terahertz Real-Time Imaging Uncooled Arrays Based on Antenna-Coupled Bolometers or FET Developed at CEA-Leti

Journal of Infrared, Millimeter, and Terahertz Waves - Sensitive and large-format terahertz focal plane arrays (FPAs) integrated in compact and hand-held cameras that deliver real-time terahertz...     

Fluorescent P-Hydroxyphosphole for Peptide Labeling through P-N Bond Formation

Synthesis of fluorescent P-hydroxybinaphtylphosphole-oxide or -sulfide was achieved by trapping a binaphtyl dianion with methyl dichlorophosphite or P-(N,N-diethylamino)dichlorophosphine, followed by oxidation or sulfuration of the P-center. After saponification or acid hydrolysis, the P-hydroxyphospholes were coupled to peptides using the coupling agent BOP, under the conditions required for the synthesis in solution or on a solid support. This new method was illustrated by the labeling of the JMV2959, a potent antagonist of the Growth Hormone Secretagogue Receptor type 1a (GHS−R1a). The labeled conjugates were used to characterize GHSR ligands by competition assays, based on Fluorescence Resonance Energy Transfer (FRET). Such P-hydroxyphosphole-oxide or -sulfide constitute a promising new class of compact fluorophores with large Stokes shift, for labeling biomolecules by grafting through the phosphorus atom.     

Synthesis of gem-diamino derivatives on solid support

Anchoring of an α-amino-acid amide residue by its amine function to a carbamate resin followed by primary amide Hofmann rearrangement led to a gem-diamino residue linked to the resin. The generated primary amine could be acylated with various carboxylic compounds offering a large variety of molecules. Furthermore, this new solid-phase strategy allowed a reliable synthesis of a gem-diamino monomeric residue which could not be easily obtained in solution due to the limited stability of monocarbamate-protected gem-diaminoalkyl derivatives.     

Amino acids as building blocks for the synthesis of substituted 1,2,4-triazoles

We report on the synthesis of 1,2,4-triazoles substituted with 2 or 3 amino acid side chains, using silver benzoate as a key reagent for the cyclization step. A complete study of the optical purity retention during the synthetic process leading to these compounds is described. In addition an improved work-up after the addition-cyclization step was also established leading to better yields and metal-free products.     

Preparation of Some Thiazolyl Hydrazone Derivatives and Evaluation of Their Antibacterial Activities

The increasing clinical importance of drug-resistant fungal and bacterial pathogens has provided additional urgency to microbiological research and to the development of new antibacterial compounds. For this purpose, new tert-butyl [1-aryl/alkyl-2[(4-aryl-2-thiazolyl)hydrazono]ethyl]carbamate derivatives were synthesized and evaluated for antibacterial activity. The reaction of Boc-L-phenylalaninal, Boc-D-phenylalaninal, Boc-L-leucinal, and Boc-L-tryptophanal with thiosemicarbazide yielded the thiosemicarbazones, which furnished the title compounds on reaction with phenacyl bromides. The new compounds were screened for antibacterial activity. The results from the bioassay tests show that some of the compounds have notable activity against Gram-positive bacteria.     

Magnetic and infrared study of CO chemisorption on silica supported nickel-copper alloys

CO adsorption at room temperature on Ni-Cu alloys supported on SiO₂ is studied by two complementary techniques, infra-red spectroscopy and magnetic methods (saturation magnetization). The bond number between CO and the metallic surface calculated from magnetic data decreases from 1.8 to 1 as the Cu content increases. Two bands attributed to CO bonded to Ni are observed (the A band in the 2000–2050 cm^?1 region, and the B band in the 1950–1900 cm^?1 region). A small band assigned to CO bonded to Cu is also detected. As Cu content increases, the intensity of the B band decreases, and a noticeable and continuous frequency shift of the three bands is observed. Experimental results are fully accounted for assuming that: (i) two adsorbed species of CO on Ni, a monodentate and a bridged species (with small amounts of other multicentered species) are formed, as suggested by Eischens and Pliskin; (ii) dilution of Ni by Cu decreases the relative abundance of the bridged (and multicentered) species for some geometric reasons previously invoked by Soma-Noto and Sachtler; (iii) surface complexes are formed between CO and Ni; however Ni remains in its metallic state. The surface complex is sensitive to the electronic environment of the metallic atom, with a frequency shift of the three infra-red bands upon alloying as a consequence.     

Photocrosslinking of elastomer systems. I. UV light-induced reactions in a blend of EPDM-benzoin derivatives

Photocrosslinking experiments were performed on elastomeric polymer films (EPDM) that contained benzoin derivatives as photosensitive initiators. Infrared (IR) and ultraviolet (UV) spectroscopy investigations were used in conjunction with physical property measurements. The results all together make it possible to discuss the crosslinking mechanism and pose interesting questions about the reactivity of benzoin derivatives in their excited states in relation to their efficiency in the crosslinking process.     

Adsorptions de H2 et de O2 sur des alliages NiCu divisés supportés sur SiO2, etudiées par mesure d'aimantation á saturation

The linear combination of surface atom orbitals to which an adatom orbital will couple plays the important role of being the essential link between the adsorbate and the semi-infinite substrate. The group orbital (as it is called) is a function of the substrate character, the local adsorption geometry, and the adatom orbital. We present the spectral densities of states appropriate to the adsorption of a hydrogen or transition metal atom on a transition metal substrate for simple geometries, and comment upon some of the implications of the results for both past and future assumptions in chemisorption theory.     

Parallel-tetrad on null geodesics in Kerr-Newman space-time

A quasi-orthonormal tetrad that is parallel-propagated along null geodesics in the Kerr and Kerr-Newman space-time is constructed explicitly.