Search

The possibility of improving dental restorative materials is investigated through the addition of two different types of fillers to a polymeric resin. These fillers, consisting of porous alumina and TiO2 nanotubes, are compared based on their common physicochemical properties on the nanometric scale. The aim was to characterize and compare the surface morphological properties of composite resins with different types of fillers using analytical techniques. Moreover, ways to optimize the mechanical, surface, and aesthetic properties of reinforced polymer composites are discussed for applications in dental treatments. Filler-reinforced polymer composites are the most widely used materials in curing dental pathologies, although it remains necessary to optimize properties such as mechanical resistance, surface characteristics, and biocompatibility. Anodized porous alumina nanoparticles prepared by electrochemical anodization offer a route to improve mechanical properties and biocompatibility as well as to allow for the controlled release of bioactive molecules that can promote tissue integration and regeneration. The inclusion of TiO2 nanotubes prepared by hydrothermal treatment in the resin matrix promotes the improvement of mechanical and physical properties such as strength, stiffness, and hardness, as well as aesthetic properties such as color stability and translucency. The surface morphological properties of composite resins with anodized porous alumina and TiO2 nanotube fillers were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and X-ray chemical analysis. In addition, the stress–strain behavior of the two composite resins is examined in comparison with enamel and dentin.

Cartilage injury defects in animals and humans result in the development of osteoarthritis and the progression of joint deterioration. Cell isolation from equine hyaline cartilage and evaluation of their ability to repair equine joint cartilage injuries establish a new experimental protocol for an alternative approach to osteochondral lesions treatment. Chondrocytes (CCs), isolated from the autologous cartilage of the trachea, grown in the laboratory, and subsequently arthroscopically implanted into the lesion site, were used to regenerate a chondral lesion of the carpal joint of a horse. Biopsies of the treated cartilage taken after 8 and 13 months of implantation for histological and immunohistochemical evaluation of the tissue demonstrate that the tissue was still immature 8 months after implantation, while at 13 months it was organized almost similarly to the original hyaline cartilage. Finally, a tissue perfectly comparable to native articular cartilage was detected 24 months after implantation. Histological investigations demonstrate the progressive maturation of the hyaline cartilage at the site of the lesion. The hyaline type of tracheal cartilage, used as a source of CCs, allows for the repair of joint cartilage injuries through the neosynthesis of hyaline cartilage that presents characteristics identical to the articular cartilage of the original tissue.

Background Accurate quality of life (QoL) data and functional results after cancer surgery are lacking for older patients. The international, multicenter Geriatric Oncology Surgical Assessment and Functional rEcovery after Surgery (GOSAFE) Study compares QoL before and after surgery and identifies predictors of decline in QoL. Methods GOSAFE prospectively collected data before and after major elective cancer surgery on older adults (≥70 years). Frailty assessment was performed and postoperative outcomes recorded (30, 90, and 180 days postoperatively) together with QoL data by means of the three-level version of the EuroQol five-dimensional questionnaire (EQ-5D-3L), including 2 components: an index (range = 0-1) generated by 5 domains (mobility, self-care, ability to perform the usual activities, pain or discomfort, anxiety or depression) and a visual analog scale. Results Data from 26 centers were collected (February 2017-March 2019). Complete data were available for 942/1005 consecutive patients (94.0%): 492 male (52.2%), median age 78 years (range = 70-95 years), and primary tumor was colorectal in 67.8%. A total 61.2% of all surgeries were via a minimally invasive approach. The 30-, 90-, and 180-day mortality was 3.7%, 6.3%, and 9%, respectively. At 30 and 180 days, postoperative morbidity was 39.2% and 52.4%, respectively, and Clavien-Dindo III-IV complications were 13.5% and 18.7%, respectively. The mean EQ-5D-3L index was similar before vs 3 months but improved at 6 months (0.79 vs 0.82; P Conclusions GOSAFE shows that older adults’ preoperative QoL is preserved 3 months after cancer surgery, independent of their age. Frailty screening tools, patient-reported outcomes, and goals-of-care discussions can guide decisions to pursue surgery and direct patients’ expectations.

Atopic dermatitis is a chronic, relapsing, non-contiguous, exudative eczema/dermatitis, which represents a complex, multi-factorial disorder, due to an impairment of the stratum corneum barrier. Currently available drugs have a low skin bioavailability and may give rise to severe adverse events. Nanotechnologies, including nano-particles, liposomes, nano-gels, nano-mixtures, nano-emulsions and other nano-carriers, offer unprecedented solutions to these issues, enabling: i) the management of different clinical forms of atopic dermatitis, especially the recalcitrant ones, i) a better bio-availability and trans-dermal drug targeted delivery at the inflammation site, ii) dose control, iii) significant improvements both in clinical symptoms and immune responses, iv) with less adverse events being reported and a better safety profile. However, some nano-sized structures could amplify and even worsen symptoms in particularly susceptible individuals. Furthermore, most studies included in the present systematic review have been conducted in-vitro or in-vivo, with few randomized controlled clinical trials (RCTs). Future investigations should adopt this design in order to enable scholars achieving robust findings and evidence. Therefore, given the above-mentioned shortcomings, further research in the field is urgently warranted., Graphical abstract The effects of nanobiotechnologies-based pharmaceutics in atopic dermatitis.Image 1, Highlights • Atopic dermatitis is a chronic, relapsing eczema/dermatitis, due to an impairment of the stratum corneum barrier. • Currently available drugs have a low skin bioavailability and may give rise to severe adverse events. • Nanotechnologies offer unprecedented solutions, enabling the management of different clinical forms of atopic dermatitis.

The immunological perturbations associated with systemic lupus erythematosus (SLE) put many patients at a higher risk of infections, including pneumococcal pneumonia. However, the uptake and utility of anti-pneumococcal vaccines in SLE patient is both controversial and not completely agreed upon. Indeed, several epidemiological studies of anti-pneumococcal vaccine safety and efficacy in SLE have reported short-term immunogenicity with elevated anti-pneumococcal antibody titres but inconsistent long-term findings, with some studies finding poor responses, mainly for long-term immune protection. Moreover, the safety and efficacy of the pneumococcal vaccine in SLE patients remains controversial due to the different types of anti-pneumococcal vaccines, and the heterogeneity of SLE patients. Several reviews addressing anti-pneumococcal vaccination in SLE patients exist, however, to the best of our knowledge, the present is the first systematic review and meta-analysis. To better understand the efficacy and safety of pneumococcal vaccination in SLE, a comprehensive literature search was performed identifying 18 studies, which have been included in the present systematic review and meta-analysis. All studies were designed as longitudinal investigations, 2, in particular, were of high quality, being randomized, double-blind trials (RCTs). Four studies had control groups. Total sample size included 601 participants. Vaccine immunogenicity in terms of subjects with protective antibody titers ranged from 36% to 97.6%. According to our systematic review and metanalysis, high erythrocyte sedimentation rate (ESR), older age, earlier SLE onset, high disease activity, and immunosuppressive therapy were predictors of poor immunogenicity, although belimumab was found to have no significant impact. With regard to safety, no serious adverse events were found, with up to one third of cases reporting mild/low-grade complaints. In conclusion, due to the high risk of pneumococcal infection in SLE patients and given the safety and, at least partial, effectiveness, according to our systematic review and meta-analysis, in such patients, preventive strategies mainly by immunization, are required in all age groups and, in those needing immunosuppressive therapy, immunization should be given prior the initiation of the treatment. PROSPERO registration code CRD42018103605.

Purpose The purpose of this in vivo study is to evaluate the acute clinical application of a multicomponent powder (Vitachelox®), including three naturally occurring standardized extracts rich in polyphenols (grape seed extract, green tea extract, oak wood/bark extract), on healthy volunteers by measuring prevention of any metal deposition within the stratum corneum (SC) following a 6-h exposure period in a polluted environment. Patients and methods In this in vivo study, we evaluated the skin protective activity of the multicomponent powder formulated in a base emulsion compared to a relevant placebo cream. Using the tape stripping method, SC samples of face skin obtained from 30 healthy volunteers were compared following a 6-h exposure in a polluted area. Results No statistically significant variations on the amount of heavy metals were found in the samples of SC cells obtained from the hemi-faces treated with the multicomponent powder, with respect to baseline. On the contrary, a significantly higher concentration of heavy metals was found in the cells samples obtained from the hemi-faces treated with the placebo cream. In particular, an increased concentration of heavy metals superior to 100% were found for iron and zinc (+130.2% and +142.6%, respectively; p

Objective: Older patients with cancer value functional outcomes as much as survival, but surgical studies lack functional recovery (FR) data. The value of a standardized frailty assessment has been confirmed, yet it's infrequently utilized due to time restrictions into everyday practice. The multicenter GOSAFE study was designed to (1) evaluate the trajectory of patients' quality of life (QoL) after cancer surgery (2) assess baseline frailty indicators in unselected patients (3) clarify the most relevant tools in predicting FR and clinical outcomes. This is a report of the study design and baseline patient evaluations. Materials & Methods: GOSAFE prospectively collected a baseline multidimensional evaluation before major elective surgery in patients (≥70 years) from 26 international units. Short−/mid−/long-term surgical outcomes were recorded with QoL and FR data. Results: 1003 patients were enrolled in a 26-month span. Complete baseline data were available for 977(97.4%). Median age was 78 years (range 70–94); 52.8% males. 968(99%) lived at home, 51.6% without caregiver. 54.4% had ≥ 3 medications, 5.9% none. Patients were dependent (ADL < 5) in 7.9% of the cases. Frailty was either detected by G8 ≤ 14(68.4%), fTRST ≥ 2(37.4%), TUG > 20 s (5.2%) or ASAIII-IV (48.8%). Major comorbidities (CACI > 6) were detected in 36%; 20.9% of patients had cognitive impairment according to Mini-Cog. Conclusion: The GOSAFE showed that frailty is frequent in older patients undergoing cancer surgery. QoL and FR, for the first time, are going to be primary outcomes of a real-life observational study. The crucial role of frailty assessment is going to be addressed in the ability to predict postoperative outcomes and to correlate with QoL and FR.

Background The purpose of this study was to evaluate the long-term efficacy and the safety of a lecithin-based delivery form of boswellic acids from Boswellia serrata (Casperome®) for the prevention of symptoms in otherwise healthy subjects with mild irritable bowel syndrome (IBS). Methods The study included 69 otherwise healthy participants with a mild form of IBS who completed a 6-month follow-up period. In total, 34 subjects were assigned to the standard management (SM) group: diet and, if needed, hyoscine butylbromide (Buscopan®) or papaverine hydrochloride + 10 mg of Atropa belladonna extract; 35 subjects were assigned to supplementation with the Boswellia serrata lecithin-based delivery form (one tablet/day; Casperome®). IBS signs and symptoms were evaluated at inclusion (T0), after 3 (T1) and 6 months (T2). The numbers of patients who needed rescue medication were recorded. Adverse events were also evaluated. Results At baseline, the groups were comparable in terms of demographic and clinical characteristics. At follow-up, compared with the SM group, the Boswellia group showed lower mean score values for almost all self-assed IBS symptoms. A significantly lower need for rescue medications and consultations or medical evaluation/admissions was found in the Boswellia group compared with the SM group. The incidence of minimal adverse events - mainly stipsis - was significantly higher in the SM group. Oxidative stress at T2 was significantly decreased in Boswellia-supplemented subjects. Conclusions Boswellia serrata lecithin-based delivery form (Casperome®) appears to be effective and safe in improving signs and symptoms in IBS subjects who are otherwise healthy, particularly in comparison with symptomatic drug treatment that may cause side effects and stiptis.

Background In this pilot non-interference clinical study we evaluated possible interactions between Quercetin Phytosome® (Quercefit™), an innovative delivery form of quercetin, and antiplatelet agents, anticoagulants, and anti-diabetic therapy in otherwise healthy subjects. Methods Interaction with antiplatelet therapy was assessed through the bleeding time (BT) test in 30 patients treated with acetylsalicylic acid, ticlopidine or clopidogrel before and after 10 days of supplementation with Quercetin Phytosome®. Interaction with anticoagulants was evaluated by measuring the International Normalized Ratio (INR) in 20 patients using warfarin or dabigatran before and after 20 days of supplementation with Quercetin Phytosome®. Lastly, glycaemia and glycated hemoglobin were measured in 12 diabetic patients treated with metformin and restricted diet before and after 20 days of supplementation with Quercetin Phytosome®. Results After 10 days of supplementation no significant difference was observed in mean BT in patients treated with acetylsalicylic acid, ticlopidine or clopidogrel at standard dosages. Similarly, after 20 days of supplementation, the INR level among patients assuming warfarin or dabigatran was not statistically different from baseline. Lastly, no statistically significant difference in mean levels of glycaemia and glycated hemoglobin was reported before and after 20 days of complementary administration of Quercetin Phytosome® in diabetic patients treated with metformin and restricted diet. Conclusions Quercetin Phytosome® does not alter the antiplatelet activity of the most common antiplatelet agents, has no impact on the INR values in stable patients treated with warfarin or dabigatran, and does not influence the metabolic control of diabetic patient treated with metformin.

Polyhemoglobin produced from pure bovine hemoglobin by reaction with PEG bis(N-succynimidil succinate) as a cross-linking agent was encapsulated in gelatin and dehydrated by freeze-drying. Free carboxyhemoglobin and polyhemoglobin microcapsules were characterized by UV-Vis spectroscopy in the absorption range 450-650 nm and cyclic voltammetry in the voltage range from -0.8 to 0.6 mV to evaluate the ability to break the bond with carbon monoxide and to study the carrier's affinity for oxygen, respectively. SEM used to observe the shape of cross-linked gelatin-polyhemoglobin microparticles showed a regular distribution of globular shapes, with mean size of ~750 nm, which was ascribed to gelatin. Atomic absorption spectroscopy was also performed to detect iron presence in microparticles. Cyclic voltammetry using an Ag-AgCl electrode highlighted characteristic peaks at around -0.6 mV that were attributed to reversible oxygen bonding with iron in oxy-polyhemoglobin structure. These results suggest this technique as a powerful, direct and alternative method to evaluate the extent of hemoglobin oxygenation.

Background We evaluated the ability of quercetin, a natural antioxidant formulated in a specific delivery system, to reduce skin inflammation induced by a variety of stimuli, including UV radiation, stimulation with a histamine solution, or contact with chemical irritants. In particular, we tested the soothing and anti-itch effect of Quercevita®, 1% cream for external use, a formulation characterized by a phospholipids-based delivery system. Patients and methods The study was a monocentric, single blind trial that enrolled a group of 30 healthy volunteers. The back of each subject was examined to identify four quadrants with no previous skin damage or naevi that were treated in order to induce a controlled and reversible form of skin stress. The areas were treated as follows: no product; Quercevita® 1% cream, 2 mg/cm2; placebo; positive control (a commercially available topical formulation containing 1% dexchlorpheniramine). Results Only quercetin phospholipids 1% and dexchlorpheniramine 1% achieved a significant reduction in erythema with comparable results: (–10.05% [P=0.00329] for quercetin phospholipids 1% vs –14.05% [P=0.00046] for the positive control). Moreover, quercetin phospholipids 1% and dexchlorpheniramine 1% were both associated with a significant decrease in mean wheal diameter: (–13.25% and –12.23% for dexchlorpheniramine 1%, respectively). Similar findings were reported for the other tested parameters. Conclusion Quercetin has a skin protective effect against damage caused by a variety of insults, including UV radiation, histamine, or contact with toxic chemical compounds. Indeed, quercetin is able to reduce redness, itching, and inflammation of damaged skin; it may also help restore skin barrier function, increasing hydration, and reducing water loss., Video abstract

BACKGROUND Curcumin is a powerful anti-oxidant that can be used to treat inflammation and pain in chronic conditions such as osteoarthrosis (OA). Phytoproflex® is characterized by an innovative delivery system that improves bioavailability of curcuminoids and could be useful in the management of OA. METHODS This 4-week registry included 56 patients with knee OA treated according to the best standard management for symptomatic OA. On top of that, 24 patients used Phytoproflex® supplement preparation (an extract containing boswellic acid 90%, curcumin 20% and valeric acid 0.8%). Patients' control of symptoms and functional capacity were evaluated through the Karnofsky Scale and standardized treadmill test, together with measurement of oxidative stress levels and use of rescue medication. RESULTS No problems of tolerability or safety were reported among subjects using the supplement. After 4 weeks, patients treated with the supplement reported a significant decrease in pain (P

BACKGROUND Oxidative stress is associated with delayed recovery and higher risk of post-training pain in triathlon athletes. Therefore, supplementation with antioxidant compounds may have a role in enhancing recovery. Quercetin presents marked antioxidant activity. In this pilot registry study, we evaluated the effects of the supplementation with a novel proprietary delivery form (phytosome®) of quercetin in amateur triathlon athletes. METHODS We employed a specific study model of triathlon according to the "Sprint" distance. The individual triathlon training included repetition of the run 8 times in 14 days. A group of athletes used quercetin phytosome® supplementation (one tablet of 250 mg quercetin phytosome® twice daily). A control group did not use supplementation. All subjects attended a baseline measurement run and a second final measurement run at day 14. At the end of the study, subjective performance, post-training pain, cramps, time to full recovery and oxidative stress were measured. RESULTS In total, 23 subjects used the supplement and 25 did not. No side effects were reported. The improvement of time to complete the run was greater in subjects on quercetin supplementation compared with the control group (-11.3% vs. -3.9%; P

AIDS patients often suffer from cognitive impairment, including distractibility, delirium, and dementia. In fact, global brain atrophy was recognized from MRI images in HIV-associated neurocognitive disorders. A number of studies have shown that a complex network of inflammatory molecules including cytokines, chemokines, growth factors, and excitatory compounds is associated with brain inflammation and damage in HIV-infected patients.

Salivary cortisol role in response to strong stressors implied in extreme exercises and in sport practice was investigated with the aim to verify the claimed benefits that steers winter swimmers to self-prescribe the trials. Specific biochemical data allow to study a variety of stressors in sports and physical exercises, including extreme ones as winter swimming. Salivary cortisol behavior was examined in winter swimmers trials and canoe, canoe-polo competitions and comparisons of results between days with and without performances were reported. Cortisol circadian rhythm in sedentary subjects was collected as control. All the subjects were selected after anamnestic-clinical checks to evaluate their physiological conditions. The circadian cortisol behavior was reported in days with competitions and trials as well as between these events. Abrupt cortisol concentration changes were detected at the time of the trials and competitions: surprisingly, large increasing and decreasing concentrations were detected in both groups. Moreover, in winter swimmers, cortisol concentration remained fairly elevated in the evening of the trial days. In days without competitions, the usual cortisol circadian rhythm was recovered in sportsmen whereas cortisol concentrations persisted at high levels up to the evening in winter swimmers. The view that an extreme sport-like exercise as the winter swimming may well pose some treats ranging from subclinical aspects up to dismetabolic pathologies and even cardiovascular risks is strengthened by results of cortisol trends, suggesting to check physiological conditions. Results demonstrate that well-being feeling can be in contrast to the claimed improvements of health.

Recently, a novel dental restorative composite based on nanostructured micro-fillers of anodic porous alumina has been proposed. While its bulk properties are promising thanks to decreased aging and drug delivery capabilities, its surface properties are still unknown. Here we investigated the surface morphology and the adhesion to tooth dentin of this composite as prepared. For comparison, we used two commercial composites: Tetric EVO Flow (Ivoclar) and Enamel HRi Plus (Micerium). The surface morphology was characterized by atomic force microscopy and the adhesion strength by tensile tests. The experimental composite is rougher than the commercial composites, with root mean square roughness of ~549 nm against 170–511 nm, and presents an adhesion strength of ~15 MPa against 19–21 MPa. These results show at the same time some proximity to the commercial composites, but also the need for optimization of the experimental material formulation.

We have devised a supramolecular edifice involving His-tagged protein A and antibodies to yield surface immobilized, uniformly oriented, IgG-type, antibody layers with Fab fragments exposed off an electrode surface. We demonstrate here that we can affect the conformation of IgGs, likely pushing/pulling electrostatically Fab fragments towards/from the electrode surface. A potential difference between electrode and solution acts on IgGs’ charged aminoacids modulating the accessibility of the specific recognition regions of Fab fragments by antigens in solution. Consequently, antibody-antigen affinity is affected by the sign of the applied potential: a positive potential enables an effective capture of antigens; a negative one pulls the fragments towards the electrode, where steric hindrance caused by neighboring molecules largely hampers the capture of antigens. Different experimental techniques (electrochemical quartz crystal microbalance, electrochemical impedance spectroscopy, fluorescence confocal microscopy and electrochemical atomic force spectroscopy) were used to evaluate binding kinetics, surface coverage, effect of the applied electric field on IgGs, and role of charged residues on the phenomenon described. These findings expand the concept of electrical control of biological reactions and can be used to gate electrically specific recognition reactions with impact in biosensors, bioactuators, smart biodevices, nanomedicine, and fundamental studies related to chemical reaction kinetics.

Rodolfo Sacco,1 Caterina Conte,2 Emanuele Tumino,1 Giuseppe Parisi,1 Sara Marceglia,3 Salvatore Metrangolo,1 Roberto Eggenhoffner,4 Giampaolo Bresci,1 Giuseppe Cabibbo,5 Luca Giacomelli4 1Department of Gastroenterology, Cisanello Hospital, Pisa, 2Endocrinology and Metabolic Diseases, Policlinico A. Gemelli, Università Cattolica del Sacro Cuore, Rome, 3Department of Engineering and Architecture, University of Trieste, Trieste, 4Department of Surgical Sciences and Integrated Diagnostics, School of Medicine, Genova University, Genoa, 5Section of Gastroenterology, DIBIMIS, University of Palermo, Palermo, Italy Abstract: Hepatocellular carcinoma (HCC) is the most common type of liver cancer and is the second cause of death due to malignancy in the world. The treatment of HCC is complex and includes potentially curative and palliative approaches. However, both curative and palliative treatments for HCC are often associated with a not-completely favorable safety/efficacy ratio. Therefore, other treatment options appear necessary in clinical practice. Transarterial radioembolization has shown a promising efficacy in terms of disease control and is associated with a good safety profile. This review discusses the use of transarterial radioembolization in HCC, with a focus on the clinical aspects of this therapeutic strategy. Keywords: hepatocellular carcinoma, transarterial radioembolization

A new nanostructured composite film based on thiol gold nanoparticles dispersed in polycarbonate and prepared by evaporating a solution of 1-dodecanthiol gold nanoparticles and polycarbonate was developed for applications as optical lenses. Lenses with superior mechanical properties, coloring and UV ray absorption and with the same transparency as the matrix were obtained. The supporting highly transparent polycarbonate matrix and the chloroform solution of thiol gold nanoparticles, 3 nm mean size, was mixed according to a doping protocol employing different concentrations of thiol gold nanoparticles vs. polycarbonate. The presence of nanoparticles in the polymer films was confirmed by the spectrophotometric detection of the characteristic absorbance marker peak at 540–580 nm. The nanostructured films obtained show a better coverage in the UV-vis range (250–450 nm) even at very low doping ratios, of the order of 1:1,000. These results offer a very promising approach towards the development of efficient nanostructured materials for applications to optical lenses.

Experiments on superconducting transition properties and power noise density experiments are performed in Ir-based transition edge sensors samples prepared by magnetron sputtering and by laser ablation techniques. The experimental temperature dependence of the resistive-superconducting transitions are compared and analyzed in terms of percolating models. Broad excess noise peak of low amplitude is detected close to the superconductive state and explained by the correlated avalanche theory.

The occurrence of wide peaks in the frequency range spanning fifteen decades from mHz to above THz was reported in the power spectra of many natural systems. Mostly, these spectral peaks appear superimposed to the 1/f noise. Actually, two different types of spectral peaks were picked out: a first type characterized by wide peaks and high 1/f slope of the overall spectral behavior, the second one by narrow peaks spanning less than one frequency decade and low slopes. Here we highlight the role of correlation among avalanches as the main source of the wide noise peaks observed. The present theory is based on first principle statistics of elementary events clustered in time-amplitude correlated avalanches. A spectral power master equation suitable to explain peaked noise spectra arising from avalanche correlations is achieved analytically. Excellent agreement with our experiments in superconductors and many other observations in biological and natural systems are reported. Our statistical model shows that avalanche correlation gives wide peaks in the power spectrum superimposed to the 1/f behavior with high slope, a typical signature of avalanche processes.

Curative treatments, including liver transplantation, surgical resection and percutaneous treatments, are the recommended therapies in BCLC-0 (Barcelona Clinic of Liver Cancer) or BCLC-A hepatocellular carcinoma (HCC). This review provides an overview of some issues of clinical importance concerning curative treatments in HCC.

Introduction Self-organized anodic porous alumina films with hexagonal pore lattice have attracted a considerable attention for biological arrays and confinement of various organic probes dyes in solutions. A molecular structure with axial symmetry in bis-heterocyclic indole chains and conjugate system, such as cyanine fluorophore Cy3 dye, was investigated here with respect to its fluorescence when loaded in the anodic alumina pores. Cyanine Cy3, stabilized in a buffer phosphate at pH 7.3, was dispersed in milli-Q water by assisted sonication to obtain a resulting concentration of 50 mM. The dark-pink solution was deposited slowly by casting method on the anodic porous alumina surface. Irradiation by mercury lamp at 530 nm wavelength was used to promote the electron transitions to upper discreet orbitals. The photon emission from this excited state was observed as fluorescence in real time from the samples. Atomic force microscopy was used to investigate the topography of anodic porous alumina before the use and it was compared with the CCD camera-microscope images. Frequency histograms showed significant reusable surface after four-cycle rinse steps in a selected surface area.

A dynamical percolative model explaining the universality of 1/ f γ noise is reported. Exponents γ ranging from 0 to 2 are obtained under the hypothesis that noise originates from random switching events between two ON-OFF states in elemental parts (switchers) of a physical system. The usual noise behaviour with γ very close to 1 in an arbitrarily wide frequency range is obtained assuming a statistical distribution of switcher relaxation time τ proportional to τ -1 , as in McWhorter's model. The impact of these results with respect to recent self-organised criticality models is discussed.

Experimental results of current noise in magnetic fields up to 1 kG after zero field cooling and field cooling are reported in bulk HgBa2CuO4+δ prepared with vapor–solid reaction in a two-temperature zone reactor. Noise measurements performed in Hg-based superconductor materials are compared with previously studied superconductors, in particular, YBa2Cu3O7−δ. A maximum in the noise is observed at the same resistance, approximately one order of magnitude lower than the normal state value and independently of the applied field. This result is consistent with experiments in bulk YBa2Cu3O7−δ samples and with percolative model simulations of lattice junctions in which the maximum is obtained at the same value of the concentration of superconducting junctions and, thus, at the same macroscopic resistance. Maximum intensity is shown to increase with magnetic field up to 1 kG, with noise values slightly higher in the field cooling procedure. Our results attest that weak-link effects, as in YBa2Cu3O7−δ, dominate superconducting properties of bulk HgBa2CuO4+δ. With respect to YBa2Cu3O7−δ, no saturation at high magnetic field in both noise and magnetoresistance measurements is observed.

The increase in voltage noise observed by increasing magnetic field in granular high-Tc superconductors is explained in the framework of a percolative model. Noise is reproduced with computer simulations of a network of junctions, many of which are randomly shorted. The network configuration is representative of interconnections ~weak links! of grains in polycrystalline bulk samples. With respect to previous percolative models, we have demonstrated that the calculated noise intensity is modified when interdependence between different configurations in the time evolution of the network is considered. The concordance with the experimental dependence of noise on resistance at different magnetic field intensities in YBa2Cu3O72d and HgBa2CuO41d supports the hypothesis that magnetic field affects the fluxon speed and thus the switching rate of weak links. @S0163-1829~98!05633-1#

High- thick films of (YBCO) were grown on Ag substrates by a cryoelectrophoretic technique, i.e. deposited by electrophoresis in a cryogenic environment. The orienting effect is provided by the application of an external magnetic field of small intensity (120 G). After sintering, these films exhibited a superconducting transition at 92 K in the electrical resistivity. Oriented films show significantly enhanced critical current densities. A detailed study of the structural and morphological properties of the film surfaces was undertaken using scanning electron microscopy, x-ray diffraction and scanning force microscopy (SFM). All microscopies revealed different types of film growth induced by the application of an external magnetic field during the cryogenic deposition showing an increasing degree of order with the field intensity (0 - 120 G). Observations of surface topography as studied by SFM are also discussed.

The formation of Hg-based HTSC materials was investigated through the development of non-conventional techniques. The former was based on a singlestep synthesis at temperatures significantly lower than usually reported. The basic idea was to exploit the low vapuur pressure of HgO at low temperatures (≈600°C) and in oxygen atmosphere to favour the solid-state reaction between HgO and precursors. Recently, a novel alternative approach essentially based on the oxygen and mercury vapours reactivity for the synthesis of the superconducting phases has been successfully developed. Basically, solid precursors (powders, pellet or thick-film forms) are processed in a two-temperature zone reactor which allowed the independent control of precursors and HgO source temperatures, the partial pressure of HgO and the total pressure during the reaction. In the latter approach, a very low mercury vapour partial pressure (intrinsically below 1–2 atm) was demonstrated to be effective for synthesizing the superconducting phase. The respective merits of both these alternative techniques will be discussed in terms of structural, morphological and magnetic measurements. The low reaction pressure common to both the techniques simplifies largely and makes safer the preparation of these materials, especially in view of applications.

A new technique, specifically designed for the preparation of preferentially oriented HTSC (YBCO and BSCCO) films on metallic substrates has been developed. The method, named cryoelectrophoresis, is essentially based on the transport by electric fields (of the order of 1 kV/cm) of charged superconducting powders kept in a cryogenic fluid (liquid nitrogen). We show that, in these conditions, it is possible to deposit the HTSC grains with a desired orientation upon the application of an appropriate magnetic field. So far conventional electrophoretic oriented deposition was made using the weak normal-state paramagnetic moment, which required the application of magnetic fields of about 9 T. In the method that we introduced, the more intense diamagnetic moment due to the superconducting state yields comparable orientation in a small field, of about 90 G. The orientation degree is pointed out through XRD measurements, from which the fraction of grains with a particular orientation with respect to the substrate is inferred: we show that, in a film deposited with an orienting magnetic field of 90 G the number of grains with the (a, b)-planes parallel to the substrate is 2–5 times greater than in samples obtained without magnetic field and an average misorientation angle of about 25 degrees is estimated.

Magnetic susceptibility measurements are reported in three systems La2CuO4+δ, La1.85Sr0.15CuO4+δ and La1.85Sr0.15Cu0.99Zn0.01O4+δ to investigate the different temperature dependences in the insulator La2CuO4+δ and in the normal state of the doped superconducting systems. The main result presented is the careful investigation of the region immediately above the superconducting transition. All the samples were prepared using the same procedure and thermal process. The Neel temperature and the deviations from reported superconductive transitions allowed to be confident on the global good quality of the samples and on the confrontability of the measurements. Three main features are observed: (1) a weak temperature dependence in both La1.85Sr0.15CuO4+δ and La1.85Sr0.15Cu0.99Zn0.01O4+δ at temperatures above 70K, (2) a large increment of the magnetic susceptibility with Zn substitution, (3) an increasing trend at decreasing temperatures below 70K, more evident in La1.85Sr0.15Cu0.99Zn0.01O4+δ, with linear trend of the magnetic susceptibility inverse. These results are discussed in terms of a reduction of the correlation length in the AFM interactions produced by the mobile holes, the Zn induced breaking of CuCu spin coupling and holes localization at temperatures immediately above the superconducting transition.

A novel technique based on a low-temperature single-step solid state reaction of stoichiometric quantities of HgO and Ba2CuO3 to produce superconducting HgBa2CuO4+x samples has been developed. The 'as-prepared' polycrystalline Hg-1201 samples had a Tc of 95 K, as obtained by the diamagnetic onset and resistivity measurements. The crystal symmetry was tetragonal with lattice parameters a=3.876(1) AA, and c=9.509(4) AA in agreement with literature data. Sample morphology consists of grains (average dimension 30 mu m) larger than in previously published works and of a needle-like structure embedding the whole sample. These results were highly reproducible over several batches. The resistive transition in magnetic field up to 8 T and a set of magnetic measurements is presented. From these measurements we obtain information about the irreversibility line, the critical current field dependence and the presence of weak links.

A new model based on percolative computation directly performed for an array system of Josephson junctions is reported. The number of percolative paths is obtained and the total critical current of the model system is estimated from 2D and 3D arrays at selected values of external magnetic field. The evolution of the critical current distribution of the junctions at increasing magnetic field is studied in view of the relevance in percolative path calculations and compared with the experimental distribution obtained fromI– V characteristics. Percolative simulation results are shown to reproduce more satisfactory experimental critical current behavior in external magnetic fields, obtained in highly porous thick YBa2Cu3O7-x films electrophoretically deposited than mere statistical averages.

Three intermetallic systems, Yb−Al, U−Au and Ce−Co, are studied as most typical examples of intermediate-valence, heavy-fermion and coexistence of both intermediate-valence and heavy-fermion effects, respectively. YbAl2 and YbAl3, the two phases stable at low temperatures in the equilibrium phase diagram of Yb−Al, are both intermediate-valence systems with Yb valence values of 2.33 and 2.79 at room temperature. The modulation of these values by variations of external parameters like temperature, pressure and chemical substitutions with proper atoms was studied by structural, magnetic and spectroscopical techniques. Two phases are given also by U with Au at low temperatures with compositions UAu2 and U14Au51: both systems exhibit heavy-fermion properties although with different ordering mechanisms. U14Au51 is an antiferromagnetic heavy-fermion system with a Neel temperature around 23 K, UAu2 shows spin-fluctuating behaviour with a saturation in theT→0 K magnetic susceptibility. Effects of substitutions with thorium were investigated only in U14Au51: competition between strong antiferromagnetic coupling and Kondo-like behaviours is observed. The Ce-rich side of the Ce−Co phase diagram shows a single Ce24Co11 phase stable at room temperature interest in the present work but in CeCo2, which was demonstrated to be intermediate valent by resonant photoemission and XAS experiments and to exibit low magnetic moment and superconducting transition. The coexistence of intermediate-valence and heavy-fermion behaviours observed in Ce24Co11 and of intermediate valence and superconductivity in CeCo2 is shown by the analyses of XPS, XAS and magnetic experiments with suitable phenomenological models.

A new family of the noble metal-actinide intermetallics was investigated. The electrical resistivity and magnetic susceptibility measurements on some pseudobinary phases in the U 14 Au 51 Th 14 Au 51 system are reported. The effects of the observed competition between strong antiferromagnetic coupling and itinerant. Kondo-like 5f states are discussed.

Photoemission spectra of pseudobinary Yb1−xMxAl2 (M = Sc, Ca) compounds derived from YbAl2 are given (hν = 40.8, 65, 181.5 and 1253.6 eV) at various stoichiometries corresponding to compressed (with Sc) and decompressed compounds (with Ca). The surface divalent Yb 4f signal depends on the chemical substitution and is stronger in the compressed compounds (2.9 times with respect to YbAl2 in the case of 80% Sc measured at 40.8 eV). Auger results are also reported. The effect is discussed in connection with the release of compression energy in the surface region.

We present photoemission results with uv and with x rays from a family of pseudobinary compounds obtained by partial substitution of Yb, with Ca or Sc, in the reference compound YbAl{sub 2}. The substitution with Ca gives rise to a decompression and the one with Sc a compression of the lattice. Ultraviolet photoemission shows the perturbation of the electron states due to chemical substitution; Sc introduces a {ital d} character extending up to about 3 eV below the Fermi level. The weights of the Yb{sup 3+} and Yb{sup 2+} multiplets given by x-ray photoemission are compared with the results from x-ray absorption; the two spectroscopies agree in YbAl{sub 2} while the relative weights Yb{sup 3+} versus Yb{sup 2+} from x-ray photoemission are definitely below the x-ray-absorption values in the compounds heavily substituted with Sc; this is interpreted as a photoemission final-state effect connected with the {ital d} character introduced by the substitution.

The evidence of excess noise in the power spectrum of many natural systems that span over the mHz to the THz, such as biological system, superconductors at dendritic regime, Barkhausen noise of magnetic system and plasma emission from nanometric transistors, was observed and related to a class of statistical models of correlated processes. Intrinsic or induced fluctuations of the elementary processes taking place in transport phenomena couple each other giving rise to time-amplitude correlated avalanches. TES sensors for X-ray microcalorimeters have shown a clear evidence that this excess noise has typical spectral behavior spanning from 100 Hz to 10 kHz. We present an analysis of the excess noise using this statistical avalanche model of TES operating on Si substrate and suspended SiN membrane.

We present Yb L III X-ray absorption spectra (XAS) from a series of valence fluctuating Yb 1- x Sc x Al 2 ( x = 0; 0.2; 0.4; 0.6; 0.8) isostructural pseudobinary alloys. Yb mean valences, as derived via a conventional intensity analysis of the Yb L III double-peak singularities, result to monotonically increase upon decresing the lattice spacing, i.e. as the crystal is progressively shrinked by increasing the Sc-content. The Yb valence vs lattice spacing trend is found to be strictly similar to that already reported on the YbAl 2 binary compound while spanning different conditions of external pressure. Discrepancies in the Yb valence evaluation outcome when comparing Yb L III XAS versus Yb 4ƒ XPS results, XAS valences being significantly higher than XPS values in the case of Sc-rich alloys ( x = 0.6 and 0.8).