Oxacycle-Fused [1]Benzothieno[3,2-b][1]benzothiophene Derivatives: Synthesis, Electronic Structure, Electrochemical Properties, Ionisation Potential, and Crystal Structure.

The molecular properties of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) are vulnerable to structural modifications, which in turn are determined by the functionalization of the backbone. Hence versatile synthetic strategies are needed to discover the properties of this molecule. To address this, we have attempted heteroatom (oxygen) functionalization of BTBT by a concise and easily scalable synthesis. Fourfold hydroxy-substituted BTBT is the key intermediate, from which the compounds 2,3,7,8-bis(ethylenedioxy)-[1]benzothieno[3,2-b][1]benzothiophene and 2,3,7,8-bis(methylenedioxy)-[1]benzothieno[3,2-b][1]benzothiophene are synthesized. The difference in ether functionalities on the BTBT scaffold influences the ionisation potential values substantially. The crystal structure reveals the transformation of the herringbone motif in bare BTBT towards π-stacked columns in the newly synthesized derivatives. The results are further justified by the simulated HOMO levels of the model compound.

Unraveling Unprecedented Charge Carrier Mobility through Structure Property Relationship of Four Isomers of Didodecyl[1]benzothieno[3,2-b][1]benzothiophene.

The structural and electronic properties of four isomers of didodecyl[1]-benzothieno[3,2-b][1]benzothiophene (C12-BTBT) have been investigated. Results show the strong impact of the molecular packing on charge carrier transport and electronic polarization properties. Field-induced time-resolved microwave conductivity measurements unravel an unprecedented high average interfacial mobility of 170 cm(2) V(-1) s(-1) for the 2,7-isomer, holding great promise for the field of organic electronics.

Huge electro-/photo-/acidoinduced second-order nonlinear contrasts from multiaddressable indolinooxazolodine.

In this work, linear and nonlinear optical properties of electro-/acido-/photoswitchable indolino[2,1-b]oxazolidine derivatives were investigated. The linear optical properties of the closed and open forms have been characterized by UV-visible and IR spectroscopies associated with DFT calculations. Nonlinear optical properties of the compounds have been obtained by ex situ and in situ hyper-Rayleigh experiments in solution. We show that protonated, oxidized, and irradiated open forms exhibit the same visible absorption and NLO features. In particular, the closed and open forms exhibit a huge contrast of the first hyperpolarizability with an enhancement factor of 40-45. Additionally, we have designed an original electrochemical cell that allows to monitor in situ the hyper-Rayleigh response upon electrical stimulus. We report notably a partial but good and reversible NLO contrast in situ during oxidation/reduction cycles. Thereby, indolinooxazolidine moieties are versatile trimodal switchable units which are very promising for applications in devices.

Maternal infibulation and obstetrical outcome in Djibouti.

OBJECTIVE: The objective of the present study was to assess the relation between female genital mutilation and obstetric outcome in an East African urban clinic with a standardized care, taking into account medical and socioeconomic status. METHODS: This was a cohort study conducted in Djibouti between October 1, 2012 and April 30, 2014. Overall 643 mothers were interviewed and clinically assessed for the presence of female genital mutilation. The prevalence of obstetric complications by infibulation status was included in a multivariate stepwise regression model. RESULTS: Overall, 29 of 643 women did not have any form of mutilation (4.5%), as opposed to 238 of 643 women with infibulation (37.0%), 369 with type 2 (57.4%), and 7 with type 1 mutilation (1.1%).Women with a severe type of mutilation were more likely to have socio-economic and medical risk factors. After adjustment, the only outcome that was significantly related with infibulation was the presence of meconium-stained amniotic fluid with an odds ratio of 1.58 (1.10-2.27), p value=0.014. CONCLUSIONS: Infibulation was not related with excess perinatal morbidity in this setting with a very high prevalence of female genital mutilation, but future research should concentrate on the relation between infibulation and meconium.

Indolinooxazolidine: a versatile switchable unit.

The design of multiresponsive systems continues to arouse a lot of interest. In such multistate/multifunctional systems, it is possible to isomerize a molecular system from one metastable state to another by application of different stimulation such as light, heat, proton, or electron. In this context, some researches deal with the design of multimode switch where a same interconversion between two states could be induced by using indifferently two or more different kind of stimuli. Herein, we demonstrate that the association of an indolinooxazolidine moiety with a bithiophene unit allows the development of a new trimode switch. A reversible conversion between a colorless closed form and a colorful open form can be equally performed by light, proton, or electrical stimulation. In addition, the oxidation of this system allows the generation of a third metastable state.

Maternal obesity and rate of cesarean delivery in Djibouti.

OBJECTIVE: To calculate the prevalence of maternal obesity and to determine the relation between obesity and cesarean delivery in an urban hospital in Djibouti. METHODS: In an observational cohort study, all women who had a live birth or stillbirth between October 2012 and November 2013 were considered for inclusion. Body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) was calculated throughout pregnancy, and women with a BMI of at least 30.0 were deemed to be obese. Multivariate logistic regression analyses were used to evaluate the relation between cesarean and obesity. RESULTS: Overall, 100 (24.8%) of 404 women were obese before 14 weeks of pregnancy, as were 112 (25.2%) of 445 before 22 weeks, and 200 (43.2%) of 463 at delivery. Obesity before 22 weeks was associated with a 127% excess risk of cesarean delivery (adjusted odds ratio 2.27; 95% CI 1.07-4.82; P=0.032). Similar trends were found when the analyses were limited to the subgroup of women without a previous cesarean delivery or primiparae. CONCLUSION: Prevalence of maternal obesity is high in Djibouti City and is related to an excess risk of cesarean delivery, even after controlling for a range of medical and socioeconomic variables.

Are the new IADPSG criteria for gestational diabetes useful in a country with a very high prevalence?

The International Association of Diabetes and Pregnancy Study Groups released new recommendations on screening methods and diagnostic criteria for gestational diabetes. The main objectives of the present study were to analyze characteristics of mothers who underwent the new screening test, and to assess the prevalence of gestational diabetes and related pregnancy complications such as the 5-minute Apgar score <7, in a urban maternity clinic in Djibouti. The effect of treating gestational diabetes was also evaluated. Totally, 231 mothers underwent the new screening test, and 106 were diagnosed as having gestational diabetes (45.9%). Mothers with gestational diabetes had an excess risk of low Apgar scores, even after adjustment for socio-economic and medical covariates, with an odds ratio of 6.34 (1.77-22.66), p value <0.005. Only 46.2% of mothers with gestational diabetes followed the recommendations regarding treatment. Among these patients, 18.6% of infants from untreated mothers had a 5-minute Apgar score <7, compared to 3.9% infants from treated mothers (p value = 0.017). After adjustment, untreated mothers still had a high excess risk of low Apgar scores, although non-significant, with an odds ratio of 4.67 (0.78-27.87), p value = 0.09. In conclusion, gestational diabetes is highly prevalent in Djibouti and is related to low Apgar scores.

Harmonic nanocrystals for biolabeling: a survey of optical properties and biocompatibility.

Nonlinear optical nanocrystals have been recently introduced as a promising alternative to fluorescent probes for multiphoton microscopy. We present for the first time a complete survey of the properties of five nanomaterials (KNbO(3), LiNbO(3), BaTiO(3), KTP, and ZnO), describing their preparation and stabilization and providing quantitative estimations of their nonlinear optical response. In the light of their prospective use as biological and clinical markers, we assess their biocompatibility on human healthy and cancerous cell lines. Finally, we demonstrate the great potential for cell imaging of these inherently nonlinear probes in terms of optical contrast, wavelength flexibility, and signal photostability.

Preparation and characterization of P(VDF-TrFE)/Al2O3 nanocomposite.

Hybrid nanocomposites based on crystalline nanoparticles dispersed in polymer matrix have been widely studied in the past few years because of the ability of these materials to combine the properties of organic polymer and inorganic nanoparticles. The aim of this work is to tune the mechanical properties of a piezoelectric polymer by adding nanoparticles to the matrix. In this paper, alumina nanoparticles were dispersed in the copolymer P(VDF-TrFE), which exhibits high piezoelectric coefficient after polarization under high electric field without needing stretching during the polarization process. Transmission electron microscopy and scanning electron microscopy demonstrate the high rate of welldispersed nanoparticles with 10% of alumina nanoparticles added to the matrix. Piezoelectric measurements indicate that P(VDF-TrFE) may be filled by up to 10 wt% of alumina while retaining its high piezoelectric properties and increasing its elastic constant by more than 20%, measured by Brillouin spectroscopy. This work opens a wide range of applications using nanoparticles with nonlinear optical, pyroelectric, magnetic, or ferroelectric properties.

Effect of ultrasonication and dispersion stability on the cluster size of alumina nanoscale particles in aqueous solutions.

This study deals with the deagglomeration of nanoparticles in low concentration suspensions in water, protic polar solvent for polymers such as poly(vinyl alcohol) (PVA). The influence of the main parameters of ultrasonication such as time, power and irradiation modes (continuous, pulsed) on the cluster size of aluminium oxide nanoparticles 1 mg/ml in aqueous solutions was investigated. Power-law dependence of size reduction on ultrasonic time was observed. The study indicated an optimum power input, i.e. at higher vibration amplitude the break up of nanoparticle clusters was no better and there was a risk of reagglomeration occurring during a long ultrasonication. Under optimal conditions, continuous and pulsed irradiations showed almost the same efficiency of deagglomeration over a given time. This result provides alternative operating conditions for attaining the smallest size of the alumina aggregates in suspension. The influence of stabilization on the cluster size was also studied. Alumina nanoparticles were stabilized by electrostatic forces against reagglomeration without the need for dispersants, and the enhancement of dispersion stability using electrostatic, steric effects had no significant effect on the aggregate size. On the contrary, the adsorption of high molecular weight polyelectrolytes onto the particle surface could lead to reagglomeration due to material bridges between particle surfaces and even flocculation.