A Novel Photoscissile Poly(ethylene glycol)‐Based Hydrogel

A novel eight‐branched poly(ethylene glycol), PEG, macromer having a nitrocinnamate moiety as a pendant group was synthesized and found to form a photoscissile hydrogel upon exposure to 365 nm radiation in the absence of photoinitiators or catalysts. The processes of photocrosslinking and photocleavage were clearly characterized by environmental scanning electron microscopy (ESEM).     

Dioxins, furans and dioxin-like PCBs: Occurrence in food and dietary intake in France

PCDD/Fs and DL-PCBs contamination data in food products consumed in France collected from national monitoring programmes (2001-04) and representing analytical results for almost 800 individual food samples were combined with food consumption data from the French national dietary survey to estimate PCDD/Fs and DL-PCBs dietary intakes, expressed as toxic equivalents (WHO-TEQs). The mean PCDD/Fs and DL-PCBs intakes were estimated as 1.8 and 2.8 pg WHO-TEQ kg^-1 b.w. day^-1, respectively, for adults (aged 15 years and over) and children (aged 3-14 years). The main contributors to total intake were fish and milk products for both children and adults (48 and 31% for adults and 34 and 43% for children, respectively). DL-PCBs constituted the largest contributor to contamination in most foodstuffs. A life-long intake estimate showed that a non-negligible part of the French population (between 20 and 28%) had an intake above the tolerable monthly intake for dioxins and dioxin-like PCBs of 70 pg WHO-TEQ kg^-1 b.w. month^-1.     

Dietary exposure of Tunisian adult population aged from 19 to 65 years old to pesticides residues

ABSTRACT

Dietary exposure of the Tunisian adult population to pesticide residue was assessed using the Total Diet Study method. In the present study 170 pesticides were searched for in 42 aggregated foods characterised by 64 food samples representing the Tunisian diet. All the food samples were collected, prepared, and analysed for remains of pesticides including organochlorine, organophosphorous, carbamates and pyrethroids. The GC-MS analysis and the LC-MS/MS analysis and some other specific analytical methods were employed for the quantification of the pesticide residues in the food samples. Results revealed that21pesticides reached amounts greater than the LOQ(12.3%) and 149 pesticides reached amounts below the LOD (88%).For the 21 pesticides quantified, the ADI was not exceeded. For the 149 non-quantified pesticides, an interval defined by the lower and upper bounds was defined to assess the dietary exposure of the Tunisian adult population to those pesticides. We conclude that 8 pesticides theoretically exceed the ADI with the 95^th percentile of exposure, those are: Diféthialone, Brodifacoum, Bromadiolone, Glufosinate, Heptachlor, Dieldrin Aldrin Oxydemeton-methyl. This study concludes that there is a low dietary exposure to pesticide residue of the Tunisian adult population. In fact, all the cases where the ADI was exceeded were theoretical due to the lower ADI value used.     

Evaluation of single ohmic metallisations for contacting both p- and n-type GaInAs

The contact resistivity of various non-alloyed ohmic contact metallisations on both n- and p-type Ga/sub 0.47/In/sub 0.53/As has been investigated. Pd/AuGe metallisation was found to be most suitable when layers of both doping types were to be contacted in a single step, having lower contact resistivities on p/sup +/-GaInAs than Ti/Pt/Au and AuBe/Pt/Au. On n/sup +/-GaInAs, the contact resistivity was found to be almost independent of the metallisation used.<>     

Widely tunable S-band fiber-ring lasers and broadband amplified spontaneous emission sources with thulium-doped fluoride fibers

This paper reports our investigation on widely tunable fiber-ring lasers and broadband amplified spontaneous emission (ASE) light sources with thulium-doped fluoride fibers (TDFs). The experimental results for thulium-doped optical fiber amplifiers will also be discussed. We achieved widely tunable fiber lasers that had tuning ranges of 94 nm with 1550 nm + 1050 nm pump configurations and of 85 nm with 1550 nm + 1400 nm pump configurations, respectively. It was observed that the lasers oscillated under multilongitudinal-mode operation with linewidth of 400 MHz, signal-to-source noise ratio of 60 dB, and power stability of 0.003 dB for a laser output of 1 mW. A broadband ASE source with a power density of more than -15 dBm/nm between 1465 and 1535 nm was also demonstrated with a novel hybrid configuration by using both TDF and erbium-doped fiber.     

Fluorescence properties of Langmuir-Blodgett films of chlorophyll a mixed with membrane lipids

The effect of the lipidic environment on the emission properties of chlorophyll a in mixed Langmuir-Blodgett films was studied. For a pigment:lipid molar ratio of 1:100, the fluorescence excitation and emission spectra have maxima at 438 nm and 678 nm respectively. Two lifetimes were necessary to fit the time-resolved fluorescence decay curves: 4.6 ns and 2.2 ns with respective contributions of 74% and 26%. The long component is attributed to the monomeric pigment and the short component to hydrated dimers or oligomers. Lecithins and galactolipids have identical effects on the emission properties of chlorophyll a, indicating that there is no specificity in the pigment-lipid interactions. However, some lipids are found to have the same effect as acids on the chlorophyll monoayers and, among them, some require careful purification in order to eliminate this acidic reaction. Those data suggest that the lipids of thylakoid membranes are good diluents and are not destructive to chlorophyll a.     

Low-frequency noise characteristics of AlInAs/GaInAs modulation-doped field-effect transistors

The output noise voltage of AlInAs/GaInAs MODFETs grown by both MOCVD and MBE was measured at frequencies from 1 MHz to 1.5 GHz under different bias conditions for the first time. For frequencies below 500 MHz the noise voltage showed a 1/f dependence with a corner frequency around 200 MHz. The low-frequency noise was larger at the bias conditions giving higher transconductance.<>     

Autoimmune thrombopenic purpura. Clinical practices during diagnosis. A French survey and recommendations. French College of Hemotologists Evaluation Commission

THE SURVEY: To better ascertain diagnostic and treatment strategies used by physicians for idiopathic thrombocytopenic purpura, a questionnaire was addressed to 298 French hematologists and pediatricians. One hundred and ten responses were analyzed. DIAGNOSTIC APPROACH: Thrombocytopenia was determined on capillary blood samples by 50% of the physicians and platelet-associated antibody by 44%. Bone marrow aspirates were obtained more frequently in adults (85%) than in children (47%) and immune disorders were more often investigated in 95% of adults and in 68% of children. THERAPEUTICS: Treatment threshold was lower in children (20.10(9)/l) than in adults (50.10(9)/l). Corticoidsteroids was the treatment of choice in adults (98%) and children received either IV immunoglobulins (61%) and/or corticosteroids (63%); higher doses were used in children (> or = 2 mg/kg versus 1 mg/kg) for shorter periods (> or = 2 weeks versus > 3 weeks). Treatment failure was evaluated earlier in children (< 10 days) than in adults (> 20 days). RECOMMENDATIONS: 1. Diagnosis. Based on repeatedly low platelet counts and verification that only platelets are involved. Clinical examination is normal excepting rare cases of severe hemorrhage. Search for antiplatelet antibodies is non-contributive 2. Treatment Short-term corticosteroids, both in children and adults. Intravenous gammaglobulins should be limited to cases with signs of severe hemorrhage. 3. Consult the complete guidelines for each individual clinical situation.