Photonics based on carbon nanotubes

Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the efficiency and power consumption of saturable absorbers (SAs) based on SWCNT with SA based on conventional multiple quantum wells. For active applications, exceptional photoluminescence properties of SWCNT, such as excellent light-emission stabilities with temperature and excitation power, hold these nanometer-scale materials as prime candidates for future active photonics devices with superior performances.     

Functional expression in insect cells, one-step purification and characterization of a recombinant phospholipase D from cowpea (Vigna unguiculata L. Walp)

Phospholipase D (PLD) is an important enzyme involved in signaltransduction, vesicle trafficking and membrane metabolism. Inthis study, large amounts of a recombinant plant PLD were secretedinto the culture medium of baculovirus-infected insect cellsand purified to homogeneity in the form of a fully active enzyme.The transient production of recombinant PLD yielded a protein(rPLDa, 88 kDa) together with a shorter form (rPLDb, 87 kDa),which accumulated in the medium. N-Terminal amino acid sequencingof the rPLDa and rPLDb showed that rPLDb resulted from proteolyticcleavage at Gly8–Ile9. Immunoblotting showed that bothrPLDa and rPLDb are recognized by a polyclonal antibody previouslyraised against native soybean PLD. One-step calcium-dependentoctyl-Sepharose chromatography was used to obtain the two highlypurified forms of rPLD, as attested by gel electrophoresis,N-terminal amino acid sequence and mass spectrometry. The N-terminalregion of PLD is homologous with the C2 domains which are presentin a number of enzymes known to be involved in signal transductionand/or phospholipid metabolism. The truncated rPLDb lacks thefirst acidic amino acid in its N-terminus, which is probablyinvolved in the calcium binding site. The rPLDb was thus easilyeluted from the octyl-Sepharose column by decreasing the calciumconcentration of the buffer from 50 to 30 mM, whereas, the rPLDawas eluted after chelating calcium ions with EDTA. The purifiedrPLD yield reached a level of 10 mg per liter of serum-freeculture medium. The availability of baculovirus-derived rPLDconstitutes a valuable source of enzyme for future crystallographicstudies to determine its three-dimensional structure.     

Controlled growth of 1D and 2D ZnO nanostructures on 4H-SiC using Au catalyst

A perfect control of nanostructure growth is a prerequisite for the development of electronic and optoelectronic device/systems. In this article, we demonstrate the growth of various ZnO-derived nanostructures, including well-ordered arrays of high aspect ratio single crystalline nanowires with preferred growth direction along the [0001] axis, nanowalls, and hybrid nanowire-nanowall structures. The growths of the various ZnO nanostructures have been carried out on SiC substrates in a horizontal furnace, using Au thin film as catalyst. From experimental observations, we have ascribed the growth mechanisms of the different ZnO nanostructures to be a combination of catalytic-assisted and non-catalytic-assisted vapor–liquid-solid (VLS) processes. We have also found that the different ZnO nanoarchitectures'' material evolution is governed by a Zn cluster drift effects on the SiC surface mainly driven by growth temperature. Au thin film thickness, growth time, and temperature are the parameters to optimize in order to obtain the different ZnO nanoarchitectures.     

Design,Synthesis, In Silico and In Vitro Studies for New Nitric Oxide-Releasing Indomethacin Derivatives with 1,3,4-Oxadiazole-2-thiol Scaffold

Starting from indomethacin (IND), one of the most prescribed non-steroidal anti-inflammatory drugs (NSAIDs), new nitric oxide-releasing indomethacin derivatives with 1,3,4-oxadiazole-2-thiol scaffold (NO-IND-OXDs, 8a–p) have been developed as a safer and more efficient multitarget therapeutic strategy. The successful synthesis of designed compounds (intermediaries and finals) was proved by complete spectroscopic analyses. In order to study the in silico interaction of NO-IND-OXDs with cyclooxygenase isoenzymes, a molecular docking study, using AutoDock 4.2.6 software, was performed. Moreover, their biological characterization, based on in vitro assays, in terms of thermal denaturation of serum proteins, antioxidant effects and the NO releasing capacity, was also performed. Based on docking results, 8k, 8l and 8m proved to be the best interaction for the COX-2 (cyclooxygense-2) target site, with an improved docking score compared with celecoxib. Referring to the thermal denaturation of serum proteins and antioxidant effects, all the tested compounds were more active than IND and aspirin, used as references. In addition, the compounds 8c, 8h, 8i, 8m, 8n and 8o showed increased capacity to release NO, which means they are safer in terms of gastrointestinal side effects.