Synthesis of oxocarbon-encapsulated gold nanoparticles with blue-shifted localized surface plasmon resonance by pulsed laser ablation in water with CO2 absorbers.

Colloidal suspensions of oxocarbon-encapsulated gold nanoparticles have been synthesized in a one-step procedure by pulsed-laser ablation (PLA) at 532 nm of a solid gold target placed in aqueous solution containing CO2 absorbers, but without any stabilizing agent. Multi-wavelength surface enhanced Raman spectroscopy allows the identification of adsorbed amorphous carbon and graphite, Au-carbonyl, Au coordinated CO2-derived bicarbonates/carbonates and hydroxyl groups around the AuNPs core. Scanning electron microscopy, energy dispersive x-ray analysis and high resolution transmission electron microscopy highlight the organic shell structure around the crystalline metal core. The stability of the colloidal solution of nanocomposites (NCs) seems to be driven by solvation forces and is achieved only in neutral or basic pH using monovalent hydroxide counter-ions (NaOH, KOH). The NCs are characterized by a blue shift of the localized surface plasmon resonance (LSPR) band typical of metal-ligand stabilization by terminal π-back bonding, attributed to a core charging effect caused by Au-carbonyls. Total organic carbon measurements detect the final content of organic carbon in the colloidal solution of NCs that is about six times higher than the value of the water solution used to perform PLA. The colloidal dispersions of NCs are stable for months and are applied as analytical probes in amino glycoside antibiotic LSPR based sensing.

Gold nanoparticles on the surface of soda-lime glass: morphological, linear and nonlinear optical characterization.

Materials presenting high optical nonlinearity, such as materials containing metal nanoparticles (NPs), can be used in various applications in photonics. This motivated the research presented in this paper, where morphological, linear and nonlinear optical characteristics of gold NPs on the surface of bulk soda-lime glass substrates were investigated as a function of nanoparticle height. The NPs were obtained by annealing gold (Au) thin films previously deposited on the substrates. Pixel intensity histogram fitting on Atomic Force Microscopy (AFM) images was performed to obtain the thickness of the deposited film. Image analysis was employed to obtain the statistical distribution of the average height of the NPs. In addition, absorbance spectra of the samples before and after annealing were measured. Finally, the nonlinear refractive index (n2) and the nonlinear absorption index (α2) at 800 nm were obtained before and after annealing by using the thermally managed eclipse Z-scan (TM-EZ) technique with a Ti:Sapphire laser (150 fs pulses). Results show that both n2 and α2 at this wavelength change signs after the annealing and that the samples presented a high nonlinear refractive index.

Chronic stress, but not hypercaloric diet, impairs vascular function in rats.

The aim of this study was to evaluate vascular and metabolic effects of chronic mild unpredictable stress (CMS) and hypercaloric diet (HD) without carbohydrate supplementation in rats. Male Sprague-Dawley rats were randomly assigned to four groups: Control, HD, CMS, and HD plus CMS. CMS consisted of the application of different stressors for 3 weeks. The rats were killed 15 days after CMS exposure. The HD group presented higher plasma lipid concentrations, without changes in fasting glucose concentration, glucose tolerance test, and vascular function and morphology, in comparison with the control group. Stressed rats presented higher fasting blood concentration of insulin, higher homeostasis model assessment index values and area under the curve in an oral glucose tolerance test, in comparison with non-stressed rats. CMS increased the plasma concentrations of corticosterone and lipids, and the atherogenic index values, without change in high-density lipoprotein level. CMS increased intima-media thickness and induced endothelium-dependent supersensitivity to phenylephrine, and lowered the relaxation response to acetylcholine in the thoracic aorta isolated from rats fed with control or HD, in comparison with non-stressed groups. CMS effects were independent of diet. In non-stressed rats, the HD induced dyslipidemia, but did not change glucose metabolism, vascular function, or morphology. The data from this study indicate that CMS promotes a set of events which together can contribute to impair function of the thoracic aorta.

[The role of endoscopic surgery in respiratory tract neoplasia]. / Il ruolo della chirurgia endoscopica nelle neoplasie dell'apparato respiratorio.

Laser therapy--either by contact or non-contact method--can be considered the best palliative option for patients affected by airway obstruction due to malignant tumors considered inoperable and/or in emergency because of inadequate ventilation. The Nd-YAG laser is widely used in endoscopy. From 1988 to September 2002 at the Department of Surgery "P Valdoni" of the University of Rome "La Sapienza" 251 clinical cases affected by airway obstruction caused by primary or metastatic malignant tumors are treated; moreover 76 stents were used. The symptomatological improvement and beneficial changes in functional breathing tests, haemogasanalysis and X-ray findings were registered 48-72 hours after each treatment. The results showed an improvement in functional breathing values especially after treatment of the main airways such as trachea and main bronchi. The therapy offered an acceptable quality of life. A fairly good number of patients may also return to radio and/or chemotherapy (if previously interrupted) and sometimes to radical surgery. In terms of costs-effectiveness, the endoscopic treatment is widely competitive.

[Special indications for the use of soft contact lenses as a drug-release-system (author's transl)]. / Besondere Indikationen für die Anwendung weicher Kontaktlinsen als Augentropfenreservoir (Drug Release System)

Research has been performed, both experimentally and clinically, to establish the value of the association of soft contact lenses and some types of eye drops. The use of soft contact lenses with eye drops may be useful in some special cases: a) more prolonged and more sustained effect compared with the usual way of administration of eye drops (especially antiglaucomatous substances, antimetabolites, mydriatics); b) possibility of reducing the concentration to avoid local discomfort or systemic side-effects, without loss of their effectiveness on the eye conditions to be treated. The combined use of soft lenses (12.5-15 mm in diameter) with eye drops may be obtained either by presoaking the lens in the liquid or by regular instillation of eye drops after insertion of the lens; the two techniques may of course be associated. In the present research the advantages of utilizing hydrophylic lenses with osmotically active substances, to obtain a better and more protracted dehydration of the cornea, were first examined, in vitro and in vivo. The following substances were tested: 10% propylenglycol, 10% glycerol, 10% glucose and 5% natrium chloride. The clearing effect of the different types of treatment was evaluated in 45 patients with edematous bullous keratopathy with an instrument which measured the infrared light emitted by an optic fiber and reflected by the cornea. The effects were more marked for the epithelial than for the stromal oedema. Another group of investigations was performed with two polypeptides with high molecular weight: Eledoisin, extracted from a mediterranean octopus, Eledone moschata, and Physalaemin, extracted from the skin of a south american batrachian, Physalaemus fuscomaculatus, both of these stimulate the lacrimal secretion and were previously successfully employed topically by the authors against keratoconjunctivitis sicca. The increase of the amount of fluid was however short-lived. Eledoisin at a concentration of 200 mug/ml, was examined in its effects both in vitro and in vivo, whereas physalaemin, at a concentration of 20 mug/ml, only in vitro, owing to the present shortage of the product. The clinical tests in 23 eyes of 14 patients with keratoconjunctivitis sicca proved satisfactory, since the lacrymal stimulating effect is not only greater, but lasts three times longer by combining the instillation of eledoisin with a presoaked soft lens. Some antiglaucomatous products (propranolol, clonidine, prostigmine) were, finally, used in association with a soft lens to reduce the concentration of the eye drops for a better tolerance locally (propranolol: a beta-adrenergic blocking agent) or generally (clonidine: alpha-adrenergic agent), also with the advantage of protracted release. With propranolol the concentration could be reduced to 0.01-0,10% (instead of 0.125 to 0.25%) and to 1.5% (instead of 3%) with prostigmine, when lenses were presoaked or instillations took place at regular time intervals, after insertion of the lenses.