Photoelectrochemical fabrication of spectroscopic diffraction gratings

Photoelectrochemical etching was demonstrated as a means of fabricating a variety of periodic structures in semiconductors. The semiconductor is used as an electrode in an electrochemical cell, and is in contact with a liquid electrolyte. When the crystal is held at a positive voltage and illuminated, etching occurs in only the illuminated regions to a depth proportional to the illumination intensity and exposure time. In Phase 1, it was determined that diffraction gratings could be produced in gallium arsenide crystals by this method, using either a scanned focused laser beam or by uniform illumination of a ruling mask defined in metal or photoresist on the crystal surface. The latter approach was determined to produce V-grooves if the mask is oriented along certain crystallographic directions. These V-grooves were produced with an exceedingly smooth crystal morphology due to the highly controllable nature of the process and the mild electrolytes involved. The results form the basis for photoelectrochemical fabrication of deep, low pitch Eschelle gratings for use in high orders in NASA spectrographic instrumentation such as the Space Telescope Imaging Spectrograph

Photoelectrochemical fabrication of spectroscopic diffraction gratings, phase 2

This program was directed toward the production of Echelle diffraction gratings by a light-driven, electrochemical etching technique (photoelectrochemical etching). Etching is carried out in single crystal materials, and the differential rate of etching of the different crystallographic planes used to define the groove profiles. Etching of V-groove profiles was first discovered by us during the first phase of this project, which was initially conceived as a general exploration of photoelectrochemical etching techniques for grating fabrication. This highly controllable V-groove etching process was considered to be of high significance for producing low pitch Echelles, and provided the basis for a more extensive Phase 2 investigation

La biodiversità

Il tema ci consente di affrontare l’evoluzione del rapporto tra terra e alimentazione, osservando i cambiamenti che hanno interessato le tecniche di produzione e l’attenzione ai problemi legati alla salute e alla tutela dell’ambiente. La vita delle generazioni passate ha sempre avuto come unico centro di riferimento la terra ed i suoi frutti: possedere un appezzamento di terra costituiva una enorme ricchezza perché garantiva il necessario sostentamento per una o più famiglie. La presenza di animali da cortile o di bestiame forniva un contributo allo svolgimento delle attività nei campi e consentiva di variare i pasti da presentare a tavola. Il rapporto del cibo con la terra era diretto, non subiva alcun tipo di passaggio, se non per raggiungere il mercato o la fiera dei paesi limitrofi, dove si proponevano la frutta e la verdura di stagione, il latte prodotto in eccedenza rispetto al fabbisogno domestico, le uova o la carne macellata direttamente dall’allevatore, sebbene molto più raramente

Health-Related Quality of Life in Patients with CVID Under Different Schedules of Immunoglobulin Administration: Prospective Multicenter Study

We assessed the health-related quality of life (HRQoL) in CVID adults receiving different schedules of immunoglobulin replacement therapy (IgRT) by intravenous (IVIG), subcutaneous (SCIG), and facilitated (fSCIG) preparations. For these patients, IgRT schedule was chosen after a period focused on identifying the most suitable individual option

Translucent zirconia in the ceramic scenario for monolithic restorations: A flexural strength and translucency comparison test

Objective: To compare three different compositions of Yttria-Tetragonal Zirconia Polycrystal (Y-TZP) ceramic and a lithium disilicate ceramic in terms of flexural strength and translucency. Methods: Three zirconia materials of different composition and translucency, Aadva ST [ST], Aadva EI [EI] and Aadva NT [NT](GC Tech, Leuven, Belgium) were cut with a slow speed diamond saw into beams and tabs in order to obtain, after sintering, dimensions of 1.2 × 4.0 × 15.0 mm and 15.0 × 15.0 × 1.0 mm respectively. Blocks of IPS e.max CAD LT were cut and crystallized in the same shapes and dimensions and used as a reference group [LD]. Beams (n = 15) were tested in a universal testing machine for three-point bending strength. Critical fracture load was recorded in N, flexural strength (σ in MPa), Weibull modulus (m) and Weibull characteristic strength (σ0 in MPa) were then calculated. Tabs (n = 10) were measured with a spectrophotometer equipped with an integrating sphere. Contrast Ratios were calculated as CR = Yb/Yw. SEM of thermally etched samples coupled with lineal line analysis (n = 6) was used to measure the tested zirconia grain size. Data were statistically analyzed. Results: Differences in translucency, flexural strength and grain size were found to be statistically significant. CR increased and flexural strength decreased in the following order ST(σ 1215 ± 190 MPa, CR 0.74 ± 0.01) > EI(σ 983 ± 182 MPa, CR 0.69 ± 0.01) > NT(σ 539 ± 66 MPa, CR 0.65 ± 0.01) > LD (σ 377 ± 39 Mpa, CR 0.56 ± 0.02). The average grain size was different for the three zirconia samples with NT(558 ± 38 nm) > ST(445 ± 34 nm) > EI(284 ± 11 nm). Conclusions: The zirconia composition heavily influenced both the flexural strength and the translucency. Different percentages of Yittria and Alumina result in new materials with intermediate properties in between the conventional zirconia and lithium disilicate. Clinical indications for Zirconia Aadva NT should be limited up to three-unit span bridges

Enhanced spontaneous raman scattering and gas composition analysis using a photonic crystal fiber

Spontaneous gas-phase Raman scattering using a hollow-core photonic bandgap fiber (HC-PBF) for both the gas cell and the Stokes light collector is reported. It was predicted that the HC-PBF configuration would yield several hundred times signal enhancement in Stokes power over a traditional free-space configuration because of increased interaction lengths and large collection angles. Predictions were verified by using nitrogen Stokes signals. The utility of this system was demonstrated by measuring the Raman signals as functions of concentration for major species in natural gas. This allowed photomultiplier-based measurements of natural gas species in relatively short integration times, measurements that were previously difficult with other systems. © 2008 Optical Society of America

ANEMIA OF INFLAMMATION: INVESTIGATION ON HEPCIDIN IN ACUTELY ILL PATIENTS AND THEIR CLINICAL OUTCOME

The anaemia of inflammation is a normochromic, normocytic anaemia, associated with abnormal iron utilization, erythropoietin hyporesponsiveness, and decreased red blood cells (RBC) survival. It is a very common problem in hospitalized patients for acute inflammatory diseases and develops within few days from the onset of illness. Hepcidin is an interleukin-6 induced hormone previously identified as an antimicrobial peptide. Now it is recognized as the master regulator of iron homeostasis in mammals allowing iron adaptation according to the body iron needs and as the key modulator of inflammation-associated anaemia. Hepcidin is found in the circulation, it is secreted mainly by hepatocytes and to a lesser extent by macrophages, T-lymphocytes and adipocytes. In 60 acutely ill patients (95% affected by infections), the degree of inflammation, indicated by IL-6 and C-RP levels, is associated with elevated concentrations of hepcidin, low iron serum levels, high transferrin saturation and very high ferritin serum levels. Moreover, persistently increased levels of hepcidin-25 on T1 and on T6 are associated with a decrease in haemoglobin during hospitalization. Patients (N=26) anaemic on T1 were still anaemic after one week. Erythropoiesis was still blunted in these patients, despite higher erythropoietin serum levels than notanaemic patients. The high levels of GDF-15 and hepcidin could have a role in the ineffective erythropoiesis. We observed that acute ill patients (N=31) admitted with normal haemoglobin levels develop anaemia after the first week of hospitalization. Analysing hepcidin levels of this subset of patients, we found that a cut-off level of hepcidin concentration of 23 nM/L was able to predict anaemia occurrence after one week with 100% of sensitivity and 90% of specificity. The inflammatory cytokines pattern and its consequence on hepcidin and iron observed in vivo in this study resembles the one described in experimental models of endotoxemia showed by Kemna et al. and by Theurl et al. Also hepcidin serum levels, haemoglobin and iron parameters are very similar to the ones found by van Eijk et al. in their investigation in septic patients admitted to intensive care units. As described in previous studies, we also demonstrated expression of hepcidin mRNA in circulating monocytes of these acutely ill patients. We found that the higher was the inflammation on admission, the higher was hepcidin mRNA expression in circulating monocytes after one week. Moreover we found negative correlation between mRNA levels of monocytes-derived hepcidin and serum ferritin, especially after one week of inflammation persistence. Analysis of interleukin-6 functional receptor (CD126 and gp130) on circulating monocytes showed a negative correlation with monocytes-derived hepcidin mRNA, and positive correlation with serum ferritin levels. These insights in anaemia of inflammation molecular mechanisms will help clinicians to better identify anaemia causes and adequately restore haemoglobin concentration with target therapies, reducing health-care requirements and healthcare costs, in-hospital stay and, finally, ameliorate health of patients

Post-Retained Single Crowns versus Fixed Dental Prostheses: A 7-Year Prospective Clinical Study

Biomechanical integrity of endodontically treated teeth (ETT) is often compromised. Degree of hard tissue loss and type of final prosthetic restoration should be carefully considered when making a treatment plan. The objective of this prospective clinical trial was to assess the influence of the type of prosthetic restoration as well as the degree of hard tissue loss on 7-y clinical performance of ETT restored with fiber posts. Two groups (n = 60) were defined depending on the type of prosthetic restoration needed: 1) single unit porcelain-fused-to-metal (PFM) crowns (SCs) and 2) 3- to 4-unit PFM fixed dental prostheses (FDPs), with 1 healthy and 1 endodontically treated and fiber post-restored abutment. Within each group, samples were divided into 2 subgroups (n = 30) according to the amount of residual coronal tissues after abutment buildup and final preparation: A) >50% of coronal residual structure or B) equal to or <50% of coronal residual structure. The clinical outcome was assessed based on clinical and intraoral radiographic examinations at the recalls after 6, 12, 24, 36, 48, and 84 mo. Data were analyzed by Kaplan-Meier log-rank test and Cox regression analysis (P < 0.05). The overall 7-y survival rate of ETT restored with fiber post and either SCs or FDPs was 69.2%. The highest 84-mo survival rate was recorded in group 1A (90%), whereas teeth in group 2B exhibited the lowest performance (56.7% survival rate). The log-rank test detected statistically significant differences in survival rates among the groups (P = 0.048). Cox regression analysis revealed that the amount of residual coronal structure (P = 0.041; hazard ratio [HR], 2.026; 95% confidence interval [CI] for HR, 1.031–3.982) and the interaction between the type of prosthetic restoration and the amount of residual coronal structure (P = 0.024; HR, 1.372; 95% CI for HR, 1.042–1.806) were statistically significant factors for survival (ClinicalTrials.gov NCT01532947)