Visible and mid-infrared spectral emissions and radiative rates calculations of Tm3+ doped BBLC glass.

Quaternary glasses with the composition 75Li2B2O7-(15-x)BaO-10CdO-xTm2O3 (BBLC) (0 ≤ x ≤ 2 mol %) have been prepared by melt-quenching method. The structure changes, the absorption coefficient of OH- and the maximum phonon energy of these glasses are studied by FT-IR spectra. Optical and emission properties of Tm3+ doped BBLC glasses have been investigated at room temperature. The optical band gap (Eopt), dispersion parameters and Urbach's energy (Eu) of the prepared samples have been estimated. Judd-Ofelt theory has been applied to obtain the radiative rates and optical intensity parameters. Oscillator strengths, radiative lifetimes, and branching ratio of different transitions have been calculated. Derived emission cross sections of the emission transitions in the visible range are determined. A strong emission is observed at 455 nm, this line is attributed to 1D2→3F4. Spectral line in the blue region has been observed at wavelength of 515 nm, as well. Two central wavelengths of 1.2 µm and 1.8 µm, which are located in the short- and mid- wave IR spectral regions, are analyzed. These emissions are attributed to the transitions 3H5→3H6 and 3F4→3H6, respectively.

An aptasensor for ochratoxin A based on grafting of polyethylene glycol on a boron-doped diamond microcell.

A novel strategy for the fabrication of an electrochemical label-free aptasensor for small-size molecules is proposed and demonstrated as an aptasensor for ochratoxin A (OTA). A long spacer chain of polyethylene glycol (PEG) was immobilized on a boron-doped diamond (BDD) microcell via electrochemical oxidation of its terminal amino groups. The amino-aptamer was then covalently linked to the carboxyl end of the immobilized PEG as a two-piece macromolecule, autoassembled at the BDD surface, forming a dense layer. Due to a change in conformation of the aptamer on the target analyte binding, a decrease of the electron transfer rate of the redox [Fe(CN)6](4-/3-) probe was observed. To quantify the amount of OTA, the decrease of the square wave voltammetry (SWV) peak maximum of this probe was monitored. The plot of the peak maximum against the logarithm of OTA concentration was linear along the range from 0.01 to 13.2 ng/L, with a detection limit of 0.01 ng/L. This concept was validated on spiked real samples of rice.

Laccase wiring on free-standing electrospun carbon nanofibres using a mediator plug.

Electrospun carbon nanofibres (CNFs) containing CNTs were produced by electrospinning and subsequent thermal treatment. This material was evaluated as a bioelectrode for biofuel cell applications after covalent grafting of laccase. Bis-pyrene-modified ABTS was used as a plug to wire laccase to the nanofibres leading to a maximum current density of 100 µA cm(-2).

Irradiation of silver and agar/silver nanoparticles with argon, oxygen glow discharge plasma, and mercury lamp.

The irradiation effect of argon, oxygen glow discharge plasma, and mercury lamp on silver and agar/silver nanoparticle samples is studied. The irradiation time dependence of the synthesized silver and agar/silver nanoparticle absorption spectra and their antibacterial effect are studied and compared. In the agar/silver nanoparticle sample, as the irradiation time of argon glow discharge plasma or mercury lamp increases, the peak intensity and the full width at half maximum, FWHM, of the surface plasmon resonance absorption band is increased, however a decrease of the peak intensity with oxygen glow plasma has been observed. In the silver nanoparticle sample, as the irradiation time of argon, oxygen glow discharge plasma or mercury lamp increases, the peak intensity of the surface plasmon resonance absorption band is increased, however, there is no significant change in the FWHM of the surface plasmon resonance absorption band. The SEM results for both samples showed nanoparticle formation with mean size about 50 nm and 40 nm respectively. Throughout the irradiation time with the argon, oxygen glow discharge plasma or mercury lamp, the antibacterial activity of several kinds of Gram-positive and Gram-negative bacteria has been examined.

E-Nose and e-Tongue combination for improved recognition of fruit juice samples.

There are many important challenges related to food security analysis by application of chemical and electrochemical sensors. One critical parameter is the development of reliable tools, capable of performing an overall sensory analysis. In these systems, as much information as possible is required in relation to smell, taste and colour. Here, we investigated the possibility of using a multisensor data fusion approach, which combines an e-Nose and an e-Tongue, adept in generating combined aroma and taste profiles. In order to shed light on this concept, classification of various Tunisian fruit juices using a low-level of abstraction data fusion technique was attempted. Five tin oxide-based Taguchi Gas Sensors were applied in the e-Nose instrument and the e-Tongue was designed using six potentiometric sensors. Four different commercial brands along with eleven fruit juice varieties were characterised using the e-Nose and the e-Tongue as individual techniques, followed by a combination of the two together. Applying Principal Component Analysis (PCA) separately on the respective e-Nose and e-Tongue data, only few distinct groups were discriminated. However, by employing the low-level of abstraction data fusion technique, very impressive findings were achieved. The Fuzzy ARTMAP neural network reached a 100% success rate in the recognition of the eleven-fruit juices. Therefore, data fusion approach can successfully merge individual data from multiple origins to draw the right conclusions that are more fruitful when compared to the original single data. Hence, this work has demonstrated that data fusion strategy used to combine e-Nose and e-Tongue signals led to a system of complementary and comprehensive information of the fruit juices which outperformed the performance of each instrument when applied separately.

Impedimetric immunosensor based on SWCNT-COOH modified gold microelectrodes for label-free detection of deep venous thrombosis biomarker.

Measurement of D-dimer has subsequently become an essential element in the diagnostics of deep vein thrombosis and pulmonary embolism; in this context microelectrodes with an area of 9×10(-4) cm(2) were used to develop impedimetric immunosensor for detecting deep venous thrombosis biomarker (D-dimer). The biosensor is based on functionalized carbon nanotubes (SWCNT-COOH) where the antibody (anti-D-dimer) was immobilized by covalent binding. The electrical properties and the morphology of the biolayer were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and atomic force spectroscopy (AFM). Impedimetric microimmunosensor allows to obtain sensitivity of 40.1 kΩ µM(-1) and detection limit of 0.1 pg/mL (0.53 fM) with linear range from 0.1 pg/mL to 2 µg/mL (0.53 fM to 0.01 µM). We demonstrate that using carbon nanotubes and microelectrodes, high sensitivity and dynamic range were obtained. The biosensor exhibited a short response time of 10 min. Moreover, the studied immunosensor exhibits good reproducibility (R.S.D. 8.2%, n=4).

Experimental study of thermodynamic surface characteristics and pH sensitivity of silicon dioxide and silicon nitride.

In this report, we have introduced a revision of the chemical treatment influence on the surface thermodynamic properties of silicon dioxide (SiO(2)) and silicon nitride (Si(3)N(4)) solid thin layers. Some characterization techniques might be used to quantify the thermodynamic properties of solid surface and predict its ability in the adhesion phenomenon. In this work, we have used static and dynamic contact angle (CA) measurements to characterize both dioxide solid surfaces being treated by using the two procedures of cleaning and chemical activation. Qualitative and quantitative concepts of analysis, using the Van Oss approach, are based on the determination of dioxide surface hydrophilic and hydrophobic features and the thermodynamic parameters such as free energy, acid, base, and Lewis acid-base surface tension components. Electrochemical capacitance-potential measurements were carried out to study the reactivity of both silicon dioxide and silicon nitride surfaces for pH variation. Furthermore, the surface roughness of these insulators was examined by using the contact angle hysteresis (CAH) measurements and atomic force microscopy (AFM). It was concluded that CA technique can be used as a suitable and base method for the understanding of surface wettability and for the control of surface wetting behavior.

Non-covalent biofunctionalization of single-walled carbon nanotubes via biotin attachment by π-stacking interactions and pyrrole polymerization.

Single-walled carbon nanotubes were functionalized with biotin using either electropolymerization or formation of pi-stacking interactions for the construction of biosensors. Thanks to the high affinity of the avidin-biotin interactions, a biotinylated glucose oxidase (B-GOX) as a biomolecule model was immobilized on the biotinylated nanotubes. The influence of the biosensor configuration on their amperometric performances was investigated by changing the amount of nanotubes and the numbers of avidin/B-GOX layers. By increasing the amount of nanotube and avidin/B-GOX layers, both sensor setups show a perfect linear increase of immobilized enzymes reflecting a high reproducibility of our systems. The highest sensitivities (up to 5.2 mA M(-1) cm(-2)) and maximum current densities (up to 55 microA cm(-2)) were obtained using nanotube deposits modified by electrochemical coatings. In contrast, non-covalently functionalized biotin-nanotubes show a better permeability for the enzymatically generated hydrogen peroxide.

Amperometric biosensors based on biotinylated single-walled carbon nanotubes.

One challenging goal for the development of biosensors is the conception of three dimensional biostructures on electrode surfaces. In this context, single-walled carbon nanotube coatings (SWCNTs), functionalized by biotin groups, were investigated to develop 3D conductive nanostructures allowing a post-functionalization by biological macromolecules. This specific anchoring of biomolecules was carried via the affinity interactions using the avidin-biotin system. For this purpose, a biotinylated pyrene was specially synthesized to develop a non-covalent functionalization based on pi-interactions between pyrene and the nanotube sidewall. SWCNT coatings were also biotinylated via electropolymerization of biotin-pyrrole derivatives at 0.95 V in CH3CN electrolyte. The resulting biotinylated SWCNTs were modified by an avidin protein via affinity interactions and characterized with scanning electron microscopy. The biofunctionalization by a biotinylated glucose oxidase (GOX) was performed by successive incubation in avidin and GOX aqueous solutions via avidin bridges. The efficiency of the enzyme anchoring was examined through the electro-enzymatic activity of the modified electrodes towards the detection of glucose at 0.7 V versus SCE. The glucose sensitivity and maximum current density were 1.6 mAM(-1) cm(-2) and 131 microAcm(-2) respectively for pyrene biotin-SWCNT electrode and 2.5 mAM(-1) cm(-2) and 178 microAcm(-2) respectively for the poly(pyrrole biotin)-SWCNT.

Insulator semiconductor structures coated with biodegradable latexes as encapsulation matrix for urease.

A new urea biosensor for clinical applications was obtained by immobilization of urease within different latex polymers functionalized by hydroxy, acetate and lactobionate groups. Responses of these biosensors based on pH-ion-selective field effect insulator-semiconductor (IS) systems to urea additions were evaluated by capacitance measurements. UV-visible spectroscopy was used to check the urease activity in various matrixes. A good retention of the catalytic urease activity in the case of the cationic polymers was observed. In addition, rotating disk electrode experiments were carried out to determine the matrix permeability characteristics. Under optimal conditions, i.e. buffer capacity corresponding to 5 mM phosphate buffer, the urea enzyme insulator semiconductor (ENIS) sensors showed a linear response for urea concentrations in the range 10(-1.5) to 10(-4)M. Furthermore, kinetic parameters for the immobilized urease were obtained from Lineweaver-Burk plot. Clearly, a fast response and a good adhesion for the urease-acetate polymer composite films, prepared without using glutaraldehyde as cross-linking agent was observed.

[Report of 2180 laparoscopic tubal ligations with the Yoon ring]. / A propos de 2180 sterilisations tubaires per-coelioscopiques par procede mecanique de Yoon.

PIP: Records of 2180 tubal sterilizations carried out using the Yoon procedure between March 1978-March 1980 in a pilot family planning clinic in Tunis, Tunisia, were examined to assess the medical, social, and psychosexual impact of the operation. Patients were seen by a social worker who obtained the couple's consent and evaluated their socioeconomic status, a midwife who took a careful medical and fertility history, and a medical specialist who ruled out pregnancy and contraindications. 2 of the 2180 women were unmarried. The average age was 34.6 years. No previous contraception had been used in 1300 cases, the pill had been used in 294, IUD in 593, and other methods in 45. 84 women had 0-3 living children, 1350 had 4-6, 682 had 7-9, and 60 had over 9. 1100 women had no induced abortions before the sterilization, 741 had 1, 197 had 2, 86 had 3, 30 had 4, and 26 had 5. Laparoscopy revealed 36 cases of pelvic infection, 29 of ovarian cysts, 14 of fibromas, 5 of varicoceles, 3 of endometriosis, 1 of G.E.U., 1 of developing mass, 1 of a mesosalpingeal granulation, and 1 of a Lippes loop. Most perioperative complications were associated with inexperienced operators; among them, 2 hematomas required laparotomy. There were 20 cases of uterine perforation. 8 cases of minor injury to abdominopelvic organs occurred but none required laparotomy. In 9 cases there was difficulty in creating the pneumoperitoneum, in 70 cases there was poor insertion of the ring, and in 7 cases there were errors in insertion of the ring. In 52 cases there were minor complications in the 1st postoperative week. 15.62% of the women later complained of pain related to the procedure, 9.71% of menstrual difficulties, .09% of fridigity, and .22% of dyspareunia. 2.17% complained of behavioral problems including anorexia, headaches, trembling and backaches, and frank psychic manifestations. 5 cases of poststerilization pregnancy were discovered, a failure rate of .08%.^ieng