The focusing capabilities of an inward cylindrical traveling wave aperture distribution and the non-diffractive behaviour of its radiated field are analyzed. The wave dynamics of the infinite ...aperture radiated field is clearly unveiled by means of closed form expressions, based on incomplete Hankel functions, and their ray interpretation. The non-diffractive behaviour is also confirmed for finite apertures up to a defined limited range. A radial waveguide made by metallic gratings over a ground plane and fed by a coaxial feed is used to validate numerically the analytical results. The proposed system and accurate analysis of non-diffractive Bessel beams launched by inward waves opens new opportunities for planar, low profile beam generators at microwaves, Terahertz and optics.
We present a full experimental characterization of isotropic artificial optical magnetism at visible frequencies produced by “raspberrylike” plasmonic nanoclusters synthesized by a bottom-up ...approach. Experimental measurements of extinction and light scattering associated with numerical simulations enable one to extract absolute values of the magnetic scattering cross section across the whole visible spectral range. The strength of the resonant magnetic response of a single magnetic nanocluster is illustrated as the effective magnetic permeability of a homogeneous sphere of identical volume.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
In this paper the focusing capability of a radiating aperture implementing an inward cylindrical traveling wave tangential electric field distribution directed along a fixed polarization unit vector ...is investigated. In particular, it is shown that such an aperture distribution generates a non-diffractive Bessel beam whose transverse component (with respect to the normal of the radiating aperture) of the electric field takes the form of a zero-th order Bessel function. As a practical implementation of the theoretical analysis, a circular-polarized Bessel beam launcher, made by a radial parallel plate waveguide loaded with several slot pairs, arranged on a spiral pattern, is designed and optimized. The proposed launcher performance agrees with the theoretical model and exhibits an excellent polarization purity.
Display omitted
•We report on the design of a suitable compliant substrate, based on Si micropillars, to grow (1 1 1) 3C-SiC films.•The new T-shape design of the pillars further improves the strain ...relaxation, preventing wafer bowing.•Growth of thick (1 1 1) 3C-SiC films allowed for the first time to study the defects evolution along the 1 1 1 direction.•Our model estimates that a stacking fault density below 5 × 102 cm−1 could be achieved in 300 μm-thick films.•We observe and explain the origin of the grain boundary closure in 3C-SiC films grown along the 1 1 1 direction.
In this paper we report the morphology and the microstructural properties of thick 1 1 1-oriented 3C-SiC films epitaxially grown on T-shaped Si micropillars. This compliant substrate was designed to release the stress developed in 3C-SiC grown on Si, due to the lattice mismatch and the different thermal expansion coefficients between 3C-SiC and Si. In this way it was possible to have 3C-SiC films as thick as 10 and 16 μm, with small bowing and no cracks. Our study relies on the use of an Electron Microscopy approach and elucidates the structure of the crystallographic defects across the 3C-SiC film, such as stacking faults (SFs), nano-twins and grain boundaries (GBs). After examination of the morphological and structural characteristics of the Si micropillar array, we analyzed the crystallographic properties of the thin 3C-SiC deposit on the Si micropillar sidewalls, since it may have an impact on the upper film. To assess the crystal quality of the 3C-SiC film, we quantified the SF density at the 3C-SiC surface, even estimating semi-quantitatively the depletion of SFs at much larger thickness. Hence, we analyzed the regions where 3C-SiC microcrystals grown on neighboring Si micropillars coalesce and form a continuous layer. We found that the coalescence between adjacent 3C-SiC microcrystals produces twinned regions, which terminate with the formation of GBs. We noticed that SFs may annihilate at the GBs, leading to the SF reduction across the 3C-SiC film. Finally, we observed the closure of the GBs inside the 3C-SiC film, thus improving the crystal quality of its surface. This work endorses the use of Si micropillars as compliant substrate to grow thick 1 1 1-oriented 3C-SiC films with good crystal quality and is preliminary to the exploitation of 3C-SiC for high performing microelectronic devices.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim was to identify the influence of conventional polymeric resin based cement (RC), hybrid polymer modified glass ionomer (RMGIC) and Zinc phosphate cement (ZPC) on the pull out strength of the ...customized zirconia post in premolars. Access cavity and root canals were performed in sixty premolar teeth with the standardized crown down technique (ProTaper Universal, Dentsply). Post space impressions were scanned, and the pre-sintered Zenostar Zr Translucent blanks (Weiland Dental, Pforzheim) were milled with the Opera-system to form the post. All prepared specimens were divided equally in three groups based on the cement type employed for luting as follows: group A: ZPC; group B (GC Fuji PLUS Capsule): RMGIC; group C (and RC (3M RelyX ARC). Ten specimens in each group were thermocycled (TC) at 5 and 55 °C in distilled water baths (40,000 cycles). Pull out bond strength was assessed using a universal testing machine at 0.5 mm/min. The means and standard deviations were compared using ANOVA and Tukey Kramer multiple comparisons tests. A significant difference among the cement groups as well as between TC and non-thermocycled (NTC) groups (
< 0.05) was observed. The highest tensile stress was demonstrated among group C (Resin, 69.89 ± 4.81 (NTC), 64.06 ± 4.36 (TC)) with the least in group A, (zinc phosphate, 43.66 ± 5.02 (NTC), 37.70 ± 5.10 (TC)) for both groups. Group A presented with 100% adhesive bond failures, followed by 80% in group C and 70% in group B, respectively. A similar outcome was observed in the TC group for the cement; however, unlike the NTC group, the TC group showed more cohesive failures compared to the NTC mixed failure. Dual cure polymer based cement demonstrated higher bond strength and efficient adhesive bonding of the customized Zr post with root dentine compared to zinc phosphate (non-polymeric) and RMGIC (hybrid polymer). Thermocycling compromised Zr post adhesive bonding to root dentin.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Metals and agrochemicals are among the main aquatic contaminants, being able to trigger oxidative stress in exposed organisms. The objective of this work was to evaluate the correlation between the ...level of oxidative stress biomarkers in Aegla crabs (Crustacea, Anomura) with (i) the set of metals present in the streams sediment and (ii) with land uses of three hydrographic basins. The study was carried out in streams (≤ 2nd order) of hydrographic basins in southern Brazil (Basins of Rio Suzana, Rio Ligeirinho-Leãozinho and Rio Dourado). In these streams were quantified the land uses and Cu, Cr, Cd, Fe, Mn and Zn concentrations in the sediment. The enzymes Catalase (CAT) and Glutathione Reductase (GR), as well as the level of membrane lipid peroxidation (TBARS), were analyzed in adult females. The PCA analysis showed that the distribution of metals was different between the basins. Cd, Cr and Fe were correlated positively with CAT and negatively with TBARS and GR. The Dourado basin had the lowest concentrations of these three metals and the highest levels of TBARS. However, in Dourado basin there is predominance of agriculture land use, and TBARS was positively correlated with agricultural land use. Besides in Dourado basin, GR activity was higher than in the others basins, indicating a compensatory response in relation to CAT inhibition. The basins of Suzana and Ligeirinho-Leãozinho rivers had lower TBARS values, which may be due to the induction of CAT in response to metals accumulated in sediment. In summary, this work indicates that in the basins with a higher concentration of toxic metals there is an adaptive response of CAT induction, which reduces TBARS in Aegla. On the other hand, in the basin with lower metallic contamination, TBARS occurrence was primarily influenced by agricultural land use.
An analytic closed-form solution is presented for the double diffraction at a pair of arbitrarily placed wedges that is suitable to be used in a uniform theory of diffraction (UTD) ray description ...framework. Here, the particular assumption, present in all the past literature, that the two diffracting edges are coplanar is removed. The doubly diffracted (DD) field at a pair of wedges is constructed via spectral synthesis. Such a procedure provides a double spectral integral representation of the DD field that is asymptotically evaluated by resorting to transition functions, typical in double diffraction problems, that can be expressed in terms of generalized Fresnel integrals. The final expression is arranged in the typical UTD fashion and contains a uniform double diffraction dyadic coefficient. The DD field behavior is analyzed in its transition regions to show how the DD field smoothly compensates for the total field discontinuities occurring at shadow boundaries where a singly diffracted field from a wedge is shadowed by the other wedge. Numerical examples are provided to verify such analysis and to test the accuracy of our UTD ray description against method of moments full wave results.
To report 3 cases of renal artery pseudoaneurysm (RAP) after partial nephrectomy and review the literature to discuss their unique presentation, clinical course, and management. RAPs are a rare ...clinical entity. They are a well-documented source of hemorrhage in association with renal biopsy, renal trauma, renal transplant, and percutaneous procedures; however, little is known about their presentation, pathophysiology, and management after nephron-sparing surgery.
Between 2000 and 2002, 698 partial nephrectomies were performed at our institution for treatment of suspected localized renal malignancy. A retrospective review of these cases revealed that 3 patients developed a postoperative RAP. These cases were reviewed along with the current medical literature available from the MEDLINE database to characterize this clinical entity further.
Three patients developed RAP after 698 uncomplicated partial nephrectomies were performed (0.43% incidence). Illustrating a classic presentation, the patient in case 1 was successfully treated with selective embolization after presenting with symptoms 3 weeks postoperatively. The patient in case 2 was treated with elective partial selective embolization for an asymptomatic lesion that later resolved spontaneously. In case 3, the patient presented early during the hospital course and required urgent selective embolization.
RAP after nephron-sparing surgery is a rare, but potentially life-threatening, condition that is often difficult to diagnose and requires a high index of suspicion. Treatment should be tailored to each patient’s clinical presentation to minimize morbidity and maximize renal conservation. All urologists should be aware of this potential postoperative complication and prepare accordingly.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
An alternative formulation is presented for the derivation of the results in which allows to rigorously extend the validity range to any incidence/observation aspect provided that the standard ...deviation of the edge roughness sigma is not large compared to the wavelength lambda while the observation distance r is r Gt lambda . This was heuristically conjectured by Franceschetti, (IEEE Trans. Antennas Propag . , vol. 56, no. 2, pp. 437-449, 2008) and supported by numerical examples, but without a rigorous proof.
PDF
![Growth of thick [1 1 1]-ori...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0264-1275/small "Growth of thick [1 1 1]-oriented 3C-SiC films on T-shaped Si micropillars")
