Coaxial nanowires as plasmon-mediated remote nanosensors.

This study reports on the plasmon-mediated remote Raman sensing promoted by specially designed coaxial nanowires. This unusual geometry for Raman study is based on the separation, by several micrometres, of the excitation laser spot, on one tip of the nanowire, and the Raman detection at the other tip. The very weak efficiency of Raman emission makes it challenging in a remote configuration. For the proof-of-concept, we designed coaxial nanowires consisting of a gold core to propagate surface plasmon polaritons and a Raman-emitting shell of poly(3,4-ethylene-dioxythiophene). The success of the fabrication was demonstrated by correlating, for the same single nanowire, a morphological analysis by electron microscopy and Raman spectroscopy analysis. Importantly for probing the remote-Raman effect, the original hard template-based process allows one to control the location of the polymer shell all along the nanowire, or only close to one or the two nanowire tips. Such all-in-one single nanowires could have applications in the remote detection of photo-degradable substances and for exploring 1D nanosources for integrated photonic and plasmonic systems.

Ion segregation in an ionic liquid confined within chitosan based chemical ionogels.

Ionogels based on in situ crosslinking of chitosan in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIm Ac) are synthesized, and studied from macroscopic properties to preferred interactions at the host matrix/EMIm Ac interface. It is highlighted that the imidazolium cations of the ionic liquid (IL) show preferred interactions with the chitosan host matrix. This exemplifies how the confinement of ILs, through an interface effect, can induce the breakdown of aggregated regions found systematically in bulk ILs and can increase the fragility of ILs. These biopolymer based ionogels could find application as biosensors and in the field of energy.

Destructuring ionic liquids in ionogels: enhanced fragility for solid devices.

Confining ionic liquids (ILs) with added lithium salt within silica host networks enhances their fragility and improves their conductivity. Overall, conductivity measurements, Raman spectroscopy of the TFSI anion and NMR spectroscopy of the lithium cation show segregative interaction of lithium ions with the SiO2 host matrix. This implies at IL/SiO2 interfaces a breakdown of aggregated regions that are found systematically in bulk ILs. Such destructuration due to the interface effect determines the fragility and thus results locally at the interface in short relaxation times, low viscosity, and good ionic conductivity. The "destructuration" of ion pairs or domains makes ILs within ionogels a competitive alternative to existing solid ionic conductors in all-solid devices, such as lithium batteries and supercapacitors.

Redirected charge transport arising from diazonium grafting of carbon coated LiFePO4.

The morphological and the electrical properties of carbon coated LiFePO4 (LFPC) active material functionalized by 4-ethynylbenzene tetrafluoroboratediazonium salt were investigated. For this purpose, FTIR, Raman, XPS, High Resolution Transmission Electron Microscopy (HRTEM) and Broadband Dielectric Spectroscopy (BDS) were considered. Electronic conductivities of LFPC samples at room temperature were found to decrease in a large frequency range upon simple immersion in polar solvents and to decrease further upon functionalization. Due to their high dipole moment, strongly physisorbed molecules detected by XPS likely add barriers to electron hopping. Significant alteration of the carbon coating conductivity was only observed, however, upon functionalization. This effect is most presumably associated with an increase in the sp(3) content determined by Raman spectroscopy, which is a strong indication of the formation of a covalent bond between the organic layer and the carbon coating. In this case, the electron flux appears to be redirected and relayed by short-range (intra chain) and long-range (inter chain) electron transport through molecular oligomers anchored at the LFPC surface. The latter are controlled by tunnelling and slightly activated hopping, which enable higher conductivity at low temperature (T < 250 K). Alteration of the electron transport within the carbon coating also allows detection of a relaxation phenomenon that corresponds to small polaron hopping in bulk LiFePO4. XPS and HRTEM images allow a clear correlation of these findings with the island type oligomeric structure of grafted molecules.

Design and Characteristics of a Multichannel Front-End ASIC Using Current-Mode CSA for Small-Animal PET Imaging.

This paper presents the design and characteristics of a front-end readout application-specific integrated circuit (ASIC) dedicated to a multichannel-plate photodetector coupled to LYSO scintillating crystals. In our configuration, the crystals are oriented in the axial direction readout on both sides by individual photodetector channels allowing the spatial resolution and the detection efficiency to be independent of each other. Both energy signals and timing triggers from the photodetectors are required to be read out by the front-end ASIC. A current-mode charge-sensitive amplifier is proposed for this application. This paper presents performance characteristics of a 10-channel prototype chip designed and fabricated in a 0.35-µm complementary metal-oxide semiconductor process. The main results of simulations and measurements are presented and discussed. The gain of the chip is 13.1 mV/pC while the peak time of a CR-RC pulse shaper is 280 ns. The signal-to-noise ratio is 39 dB and the rms noise is 300 µV/√(Hz). The nonlinearity is less than 3% and the crosstalk is about 0.2%. The power dissipation is less than 15 mW/channel. This prototype will be extended to a 64-channel circuit with integrated time-to-digital converter and analog-to-digital converter together for a high-sensitive small-animal positron emission tomography imaging system.

Sorption and transport of salicylate in a porous heterogeneous medium of silica quartz and goethite.

Among transport studies of solutes in porous media, few works have combined microscopic speciation with macroscopic-scale investigations to describe the impact of antecedent sorbed silica on the transport of organic ligands in porous heterogeneous media. In this study, the sorption of salicylate (SA) to goethite-coated sand (GCS) was investigated under static and dynamic conditions by combining batch experiments and column tests with infrared spectroscopy. On the basis of infrared spectra, the salicylate adsorption was described by one type of iron site and a mononuclear bidentate surface complex. The intrinsic complexation constant deduced from batch modeling was successfully applied to estimate the sorbed amount under flow through conditions at various water velocities (0.038-0.768 cm/min). The shape of the breakthrough curve of SA was characterized by two fronts in both SA concentration and pH. This behavior could be likely explained by the mobilization of initially adsorbed silica from goethite surface upon SA sorption. The SA breakthrough can be interpreted as retention of SA on available surface sites up to their saturation and then on additional reactive sites, becoming free due to silicate desorption. This present work demonstrated the importance of sorbed silicate on Fe-oxides in the prediction of reactive transport of organic species on natural surfaces.

Electrochemical properties and Fourier transform-infrared spectroscopic investigations of the redox behaviour of poly(indole-5-carboxylic acid) in LiClO4-acetonitrile solutions.

Electropolymerisation of indole-5-carboxylic-acid leads to the formation of electroactive polymer films. Potentiostatic deposition of the related polymer, poly(indole-5-carboxylic-acid), was carried out at a constant potential at 1.35 V versus SCE. The cyclic voltammogram of the resulting polymer in LiClO4 (0.15 mol dm(-3))/acetonitrile solution is characterized by two poorly resolved anodic and cathodic set peaks. FTIR spectroscopy was used to characterize both reduced and oxidized forms of poly(indole-5-carboxylic-acid). Assignments of the vibrational modes were proposed by comparison of the vibrational spectra of polyindole and polycyanoindole. The polymerization sites correspond to the 2 and 3 carbon positions of the pyrrole cycle. In the oxidized form of the polymer, the NH group is deprotonated while the quinoid form is present between the pyrrole rings.

Effects of dietary protein restriction and amino acids deficiency on protein metabolism in dogs.

Although stable isotope methods have been used to revisit the protein and amino acid requirements of humans in the last two decades, estimates of the minimum protein requirement of the dog have mainly been based on nitrogen balance studies. The aim of this study was: (i) to assess dog protein metabolism using the (13)C-leucine method, and (ii) to test the effects of protein deprivation and amino acid deficiency on protein metabolism. Eight dogs were fed three consecutive diets: (i) a normoprotein regimen [control; 63 g crude protein (CP)/Mcal metabolizable energy (ME)]; (ii) a protein-restricted diet (PR; 32 g CP/Mcal ME); and (iii) a protein-restricted diet that was, in addition, deficient in lysine and tryptophan (D-PR; 31 g CP/Mcal ME). The energy supply was similar for the three diets. The dogs were adapted to each diet for 2 weeks. After a 24 h fasting period, a 3 h infusion of (13)C-bicarbonate was performed, followed by a 3 h continuous infusion of L-[1-(13)C]leucine. Blood and breath samples were collected before and during the last hour of each isotope infusion for determination of plasma (13)C-alpha-ketoisocaproate and breath (13)CO(2) enrichments by mass spectrometry. Rates of protein breakdown, oxidation, and synthesis were calculated from leucine appearance into plasma, oxidation, and non- oxidative disposal, respectively, and expressed in g N/kg body weight (BW)0.75 per day, assuming body protein contains 0.08 g leucine per g protein. Protein breakdown was 3.71 +/- 0.17, 3.29 +/- 0.16 and 2.73 +/- 0.18 (mean +/- SEM) for control, PR, and D-PR, respectively (p < 0.01 D-PR versus control, and p < 0.05 D-PR versus PR). Protein synthesis was 3.08 +/- 0.13, 2.77 +/- 0.13, and 2.15 +/- 0.18 for control, PR and D-PR, respectively (p < 0.001 D-PR versus control, and p < 0.05 D-PR versus PR). Protein oxidation was 0.63 +/- 0.05, 0.53 +/- 0.05 and 0.58 +/- 0.05 for control, PR and D-PR, respectively (p=NS). These data suggest that: (i) the (13)C-leucine method can be used to assess large variations of protein turnover in dogs; (ii) dogs have the capacity to adapt their protein turnover to the level and to the quality of their protein supplies; and (iii) the dog nitrogen requirement for maintenance may be between 0.41 and 0.55 g N/kg BW(0.75) per day.

Use of L-[(15)N] glutamic acid and homoglutathione to determine both glutathione synthesis and concentration by gas chromatography-mass spectrometry (GCMS).

A method for simultaneous measurement of both glutathione enrichment and concentration in a biological sample using gas chromatography mass spectrometry is described. The method is based on the preparation of N,S-ethoxycarbonylmethyl ester derivatives of glutathione, and the use of homoglutathione (glutamyl-cysteinyl--alanine) as an internal standard. A procedure for determination of glutamate concentration and enrichment is also reported. Both methods have within-day and day-to-day inter-assay coefficients of variation less than 5%, and recoveries of known added amounts of glutathione and glutamate are close to 100%. Taken together, these methods allowed determination of glutathione concentration and fractional synthesis rate in red blood cells using L-[(15)N] glutamic acid infusion. This approach was applied in vivo to investigate the effects of a 72 h fast, compared with a control overnight fast, on erythrocyte glutathione in a single dog. The 72 h fast was associated with a 39% decline in erythrocyte glutathione level, (2.9 +/- 0.4 versus 4.7 +/- 0.5 mmol l(-1), fasting versus control) with no change in glutathione fractional synthesis (67.4 versus 71.3% d(-1), fasting versus control).

Protein restriction and dexamethasone as a model of protein hypercatabolism in dogs: effect of glutamine on leucine turnover.

To determine (1) whether protein restriction, combined with glucocorticosteroid treatment, can be used as a hypercatabolic model and (2) if so, whether glutamine attenuates protein wasting in this model, the effects of protein restriction, dexamethasone, and glutamine on leucine metabolism were assessed in dogs. A control group (n = 8) received a maintenance diet; another group (n = 8) received a protein-restricted diet either (1) alone; (2) along with a 7-day corticoid treatment; or (3) along with a 7-day corticoid treatment and a 7-hour intravenous (IV) glutamine infusion. The last day of each regimen, dogs underwent an IV isotope infusion in the fasting state, with a 3-hour NaH(13)CO3 infusion to assess CO2 production, and immediately thereafter, a 3-hour (13)C-leucine infusion to assess leucine appearance rate (Ra), oxidation (Ox), and nonoxidative leucine disposal (NOLD), expressed as micromol x kg(-1) x h(-1). Protein restriction was associated with a 24% decline in leucine Ra (223 +/- 16 v 298 +/- 17; P <.01), an index of whole body proteolysis, and a 29% decline in NOLD (180 +/- 15 v 223 +/- 13; P <.01), an index of whole body protein synthesis. In the protein-restricted group, dexamethasone treatment was associated with a 32% increase in Ra, (295 +/- 28 v 223 +/- 16; P <.05), a 186% increase in Ox (120 +/- 14 v 43 +/- 4; P <.001), with no change in NOLD, when compared with the protein-restricted alone. After protein restriction + dexamethasone, glutamine infusion induced a 40% increase in plasma glutamine (1,090 +/- 70 v 780 +/- 29 micromol x L(-1); P <.01), but failed to alter Ra, Ox, or NOLD. These results suggest that (1) in dogs, protein restriction combined with a 7-day course of dexamethasone results in alterations in leucine kinetics similar to those observed in stress-induced protein wasting in humans, and (2) in that model, a 7-hour IV glutamine infusion in the fasting state does not significantly attenuate protein wasting.

[Direct cost assessment of wrist fractures]. / Evaluation du coût direct des fractures du poignet.

PURPOSE OF THE STUDY: The cost effectiveness of wrist fractures in 1996 at Pitié-Salpétrière Hospital in Paris has been thoroughly analysed. The purpose of this retrospective study was to identify the factors responsible for the variation in the treatment cost of those fractures. MATERIAL AND METHODS: Cost, hospital stay, functional status, ASA score and surgical treatment were analysed in 53 patients with a median age of 57 years. RESULTS: The mean cost per patient was 6,120 FF divided as follows: 26.1% for pre-operative care, 36.4% for surgical procedures, 37.5% for post-operative care. The mean hospital stay was 4.3 days. The cost of personnel (43%) and medical investigations (35%) were the two main sources of hospital expenses beside medical materials (12.5%), hostelry (5.5%), and drugs (4%). DISCUSSION: The duration of hospital stay, the age and the type of the fracture were the only factors that affected statistically the mean cost per patient. Furthermore, factors related to the patient as sex, place of residence prior to admission, functional status, ASA score, had no influence on cost variation. CONCLUSION: Therefore, the best way to reduce the cost of wrist fractures management is to minimize the hospital stay before and after surgical procedure to avoid a lengthy and costly hospital stay and to minimize the abuse utilisation of systematic medical investigations.

Nonstructural protein 2 (NS2) of respiratory syncytial virus (RSV) detected by an antipeptide serum.

The human respiratory syncytial virus (RSV) is often associated with airway obstruction and is suspected to induce bronchial hyperreactivity. Interactions of viral proteins with cellular components may be responsible for epithelial damage leading to bronchial hyperreactivity. In this study, we describe the localization of the 14.7-kD nonstructural protein 2 (NS2) in RSV-infected cells. The detection of NS2 was performed using antipeptide antibodies elicited against amino acids 109-123 of the predicted sequence of the NS2 protein. By using recombinant NS2, we could clearly demonstrate the specificity of the antipeptide antibodies. With this defined tool, NS2 could be first detected in infected HEp-2 cells at 10 h p.i. subsequently to the detection of N protein. In double-staining experiments, colocalization of NS2, P protein and N protein was demonstrated. The antipeptide antibodies recognized the NS2 protein in the sediment of RSV-infected HEp-2 cells lysed with RIPA buffer at 48 h p.i. The results agree with the reported interaction of RSV with cytoskeletal intermediate filaments. These interactions may implicate essential cellular functions suspected to induce bronchial hyperreactivity.

Effect of respiratory syncytial virus-antibody complexes on cytokine (IL-8, IL-6, TNF-alpha) release and respiratory burst in human granulocytes.

The release of interleukin-8 (IL-8), IL-6, and tumour necrosis factor-alpha (TNF-alpha) from human polymorphonuclear granulocytes (PMN) after exposure to infectious respiratory syncytial virus (RSV) particles was investigated. Our data showed that PMN secreted IL-8 and IL-6 in a time- and RSV-dose-dependent manner. During the RSV exposure, TNF-alpha was not detected in the cell supernatant of PMN. Similar amounts of IL-8 were secreted after either incubation with infectious or UV-inactivated RSV particles. Obviously, PMN bind and phagocytose the viral particles, which leads to the secretion of cytokines. The increased IL-8 secretion was accompanied with an enhanced cytoplasmic IL-8 mRNA steady state level, as shown by Northern blot analysis. The IL-8 secretion pattern from PMN was also studied after its interaction with RSV--antibody complexes. Non-neutralizing monoclonal antibodies (mAb) directed to the RSV fusion protein and glycoprotein were used to generate immune complexes. Only the mAb directed to the RSV fusion protein enhanced the IL-8 release from PMN significantly. In addition, the chemiluminescence response from PMN was analysed after exposure of the cells to RSV particles, RSV-mAb complexes, Ca-ionophore A23187 or N-formyl-methionyl-leucyl-phenylalanine (FMLP). The phagocytosis of RSV inhibited the oxygen radical production induced by the Ca-ionophore A23187 or FMLP. Only RSV-anti-fusion protein mAb complexes generated a chemiluminescence response from PMN. Thus, PMN play an important role in the control of RSV infection.

Interleukin-8, interleukin-6, and soluble tumour necrosis factor receptor type I release from a human pulmonary epithelial cell line (A549) exposed to respiratory syncytial virus.

The release of interleukin-8 (IL-8), interleukin-6 (IL-6) and the soluble forms of the tumour necrosis factor receptor (sTNF-R) from human pulmonary type II-like epithelial cells (A549) after respiratory syncytial virus (RSV) infection was analysed. RSV infection alone induced a time- and RSV dose-dependent IL-8 and IL-6 release from A549 cells. Furthermore, the soluble form of the TNF-RI was also secreted in a time- and RSV dose-dependent fashion. The soluble TNF-RII was not detected in the cell supernatant of infected epithelial cells. The effect of various cytokines [IL-1 alpha/beta, TNF-alpha/beta, IL-3, IL-6, interferon-gamma (IFN-gamma), transforming growth factor-beta 2 (TGF-beta 2)] and colony-stimulating factors [granulocyte (G)-CSF; granulocyte-macrophage (GM)-CSF] on the IL-8 release from A549 cells was also studied. Our data show that the proinflammatory cytokines IL-1 alpha/beta and TNF-alpha/beta induced an IL-8 release in non-infected A549 cells, and increased the IL-8 release of RSV-infected A549 cells synergistically. In addition, IL-3, G-CSF, IFN-gamma and TGF-beta 2, albeit at high concentrations, induced a low IL-8 release from non-infected A549 cells. The enhanced IL-8 secretion rates were accompanied with elevated cytoplasmic IL-8 mRNA steady state levels, as was shown by Northern blot analysis. Cellular co-culture experiments performed with A549 cells and polymorphonuclear granulocytes or peripheral blood mononuclear cells revealed that increased IL-8 amounts were secreted in the co-culture of non-infected as well as RSV-infected cells. The present study suggests a central role for the airway epithelium during RSV infection with regard to cytokine and cytokine receptor release, resulting in a recruitment and activation of inflammatory and immune effector cells. Our data also suggest that paracrine cytokine networks and cell-cell contact are involved in the regulation of IL-8 secretion within the microenvironment of the bronchial epithelium.

[Effect of the humoral immune response on the pathogenesis of respiratory syncytial virus (RSV) infection]. / Beitrag der humoralen Immunantwort zur Pathogenese der Respiratory-Syncytial-Virus-(RSV-)Infektion.

Direct cytopathic effects and components of the humoral immune response may contribute to the pathogenesis of respiratory syncytial virus (RSV) infections. Using synthetic peptides as an analytical tool, it could be demonstrated that the primary immune response of young children is directed against other epitopes compared to the situation in adults. RSV-specific antibodies are not only considered to possess protective properties but also to contribute to the pathogenesis of the infection. In our experiments, human adherent cells from lavage could be infected by RSV more effectively in the presence of murine monoclonal antibodies specific for RSV surface proteins.

Jones matrices of tilted birefringent plates in atunable dye laser: modes at low gain and temperature effects.

The Jones matrices of tilted birefringent plates that are used as a tunable device in a laser cavity are established in order to compute the resonance modes. The results are compared with experimental spectra of a dye laser that contains this device at low gain. The temperature effect on the filter is also described.