Real-time optical spectrum analyzers operating with spectrally incoherent broadband continuous-wave light source

On the framework of coherence theory we discuss the averaged temporal intensity output provided by real-time optical Fourier transformers when the spectral line shape of the stationary source is considered. Some numerical examples are given and the deviations from perfectly monochromatic sources are pointed out.     

On the role of the bridging dicyanamidobenzene ligand in a new binuclear ruthenium complex: [{Ru(tpy)(thd)}2(mu-dicyd)][PF6] with tpy = 2,2':6',2' '-terpyridine and thd = 2,2,6,6-tetramethyl-3,5-heptanedione

The dicyanamidobenzene-bridge diruthenium complex [{Ru(tpy)(thd)}(2)(mu-dicyd)][PF(6)] ([3][PF(6)]) (dicyd = 1,4-dicyanamidobenzene, tpy = 2,2':6',2' '-terpyridine, thd = 2,2,6,6-tetramethyl-3,5-heptanedione) and its mononuclear counterpart [Ru(tpy)(thd)(Ipcyd)] (2) [Ipcyd = 4-iodophenylcyanamide anion (Ipcyd(-))] were synthesized and fully characterized. Cyclic voltammetry of 3 showed the presence of four reversible one-electron redox couples. UV-vis-NIR spectroelectrochemistry and EPR spectroscopy of the electrogenerated paramagnetic intermediates were used to ascertain the oxidation-state distribution. The stable starting dinuclear complex 3(+) is found to be a ligand-centered anion radical as shown by EPR spectroscopy, magnetic susceptibility measurements, and DFT calculations. Oxidation of 3(+) to 3(2+) led to an EPR silent system due to substantial intramolecular antiferromagnetic interaction of the electron spins carried by the low spin ruthenium(III) atom and the bridging anion radical dicyanamido (dicyd(*)(-)), an observation which was supported by UV-vis-NIR, X-ray structure, and DFT calculations. Complex 3(3+) presented an EPR spectra consistent with a total effective spin S = (1)/(2) issued from an antiferromagnetic interaction of electron spins carried by two low spin ruthenium(III) atoms and the bridging anion radical dicyd(*)(-) in accordance with UV-vis-NIR. This study shows that the dicyanamidobenzene bridging ligand has indubitably a noninnocent behavior.     

Design of original bioactive formulations based on sugar-surfactant/non-steroidal anti-inflammatory catanionic self-assemblies: a new way of dermal drug delivery

A new kind of catanionic assembly was developed that associates a sugar-based surfactant with a non-steroidal anti-inflammatory drug (NSAID). Three different assemblies using indomethacin, ibuprofen and ketoprofen as NSAIDs were easily obtained in water by an acid-base reaction. These assemblies formed new amphiphilic entities because of electrostatic and hydrophobic effects in water and led to the spontaneous formation of vesicles. These catanionic vesicles were then tested as potential NSAID delivery systems for dermatological application. The anti-inflammatory activity was evaluated in vivo, and this study clearly showed an improved therapeutic effect for NSAIDs that were formulated as catanionic vesicles. These vesicles ensured a slower diffusion of the NSAID through the skin. This release probably increased the time of retention of the NSAID in the targeted strata of the skin. Thus, the present study suggests that this catanionic bioactive formulation could be a promising dermal delivery system for NSAIDs in the course of skin inflammation treatment.     

Mixed Oligoureas Based on Constrained Bicyclic and Acyclic β‐Amino Acids Derivatives: On the Significance of the Subunit Configuration for Folding

The combination of a non‐functionalized constrained bicyclo[2.2.2]octane motif along with urea linkages allowed the formation of a highly rigid 2.5_12/14 helical system both in solution and the solid state. In this work, we aimed at developing stable and functionalized systems as promising materials for biological applications in investigating the impact of this constrained motif and its configuration on homo and heterochiral mixed‐oligourea helix formation. Di‐, tetra‐, hexa‐, and octa‐oligoureas alternating the highly constrained bicyclic motif of (R) or (S) configuration with acyclic (S)‐β³‐amino acid derivatives were constructed. Circular dichroism (CD), NMR experiments, and the X‐ray crystal structure of the octamer unequivocally proved that the alternating heterochiral R/S sequences form a stable left‐handed 2.5‐helix in contrast to the mixed (S/S)‐oligoureas, which did not adopt any defined secondary structure. We observed that the (?)‐synclinal conformation around the C_α? C_β bond of the acyclic residues, although sterically less favorable than the (+)‐synclinal conformation, was imposed by the (R)‐bicyclic amino carbamoyl (BAC) residue. This highlighted the strong ability of the BAC residue to drive helical folding in heterochiral compounds. The role of the stereochemistry of the BAC unit was assessed and a model was proposed to explain the misfolding of the S/S sequences.     

Development of Effective Skin Cancer Treatment and Prevention in Xeroderma Pigmentosum

Xeroderma pigmentosum (XP) is a rare, recessively transmitted genetic disease characterized by increasingly marked dyspigmentation and xerosis (dryness) of sun‐exposed tissues, especially skin. Skin cancers characteristically develop in sun‐exposed sites at very much earlier ages than in the general population; these are often multiple and hundreds or even thousands may develop. Eight complementation groups have been identified. Seven groups, XP‐A…G, are associated with defective genes encoding proteins involved in the nucleotide excision DNA repair (NER) pathway that recognizes and excises mutagenic changes induced in DNA by sunlight; the eighth group, XP‐V, is associated with defective translesion synthesis (TLS) bypassing such alterations. The dyspigmentation, xerosis and eventually carcinogenesis in XP patients appear to be due to their cells’ failure to respond properly to these mutagenic DNA alterations, leading to mutations in skin cells. A subset of cases, especially those in some complementation groups, may develop neurological degeneration, which may be severe. However, in most XP patients, in the past the multiple skin cancers have led to death at an early age due to either metastases or sepsis. Using either topical 5‐fluorouracil or imiquimod, we have developed a protocol that effectively prevents most skin cancer development in XP patients.     

Aromatic CC Bonds as Dipolarophiles: Facile Reactions of Uncomplexed Electron‐Deficient Benzene Derivatives and Other Aromatic Rings with a Non‐Stabilized Azomethine Ylide

Non‐stabilized azomethine ylide 4 a reacts smoothly at room temperature with a variety of uncomplexed aromatic heterocycles and carbocycles on the condition that the ring contains at least one or two electron‐withdrawing substituents, respectively. Aromatic substrates, including pyridine and benzene derivatives, participate as 2 π components in [3+2] cycloaddition reactions and interact with one, two, or three equivalent(s) of the ylide, depending on their structure and substitution pattern. Thus, this process affords highly functionalized polycyclic structures that contain between one and three pyrrolidinyl ring(s) in useful yields. These results indicate that the site selectivity of the cycloaddition reactions strongly depends on both the nature and the positions of the substituents. In most cases, the second 1,3‐dipolar reaction occurs on the opposite face to the one that contains the first pyrrolidinyl ring. DFT calculations on model compounds indicate that a concerted mechanism features a low activation barrier.     

Determination of the enantiomeric excess of α-hydroxy acids

This work describes a convenient and accurate method for optical purity determination of α-hydroxy acids. Their derivatization with commercially available valine methyl ester affords diastereoisomers easily separable by HPLC using achiral C₁₈ columns.     

Morphology-to-properties correlations in anodic porous InP layers

In this paper, we investigate the properties of porous structures anodically grown onto n-InP (100) in HCl. In situ electrochemical characterizations show the pore morphology strongly influences the properties of the InP surfaces. Both dc- and ac-electrochemical measurements reveal an enhancement of the capacitive current and a modification of the electronic distribution at the interface. Photocurrent spectra performed during the pore growth are also strongly modified. For low anodic charges, an increase of the photocurrent with a redshift of the absorption edge is measured. These evolutions can be respectively ascribed (i) to a reflection decrease due to a surface roughening and (ii) to the creation of surface states within the band gap. For higher anodic charges, the photocurrent drops with a narrowing of the spectrum. Using a model based on the “dead” layer, the porous layer is considered as an absorbent film that progressively attenuates the photocurrent of the bulk semiconductor.