Verifying the band gap narrowing in tensile strained Ge nanowires by electrical means.

Group-IV based light sources are one of the missing links towards fully CMOS compatible photonic circuits. Combining both silicon process compatibility and a pseudo-direct band gap, germanium is one of the most viable candidates. To overcome the limitation of the indirect band gap and turning germanium in an efficient light emitting material, the application of strain has been proven as a promising approach. So far the experimental verification of strain induced bandgap modifications were based on optical measurements and restricted to moderate strain levels. In this work, we demonstrate a methodology enabling to apply tunable tensile strain to intrinsic germanium [Formula: see text] nanowires and simultaneously perform in situ optical as well as electrical characterization. Combining I/V measurements and µ-Raman spectroscopy at various strain levels, we determined a decrease of the resistivity by almost three orders of magnitude for strain levels of âˆ¼5%. Thereof, we calculated the strain induced band gap narrowing in remarkable accordance to recently published simulation results for moderate strain levels up to 3.6%. Deviations for ultrahigh strain values are discussed with respect to surface reconfiguration and reduced charge carrier scattering time.

Nodal superconducting exchange coupling.

A superconducting spin valve consists of a thin-film superconductor between two ferromagnetic layers. A change of magnetization alignment shifts the superconducting transition temperature (ΔΤc) due to an interplay between the magnetic exchange energy and the superconducting condensate. The magnitude of ΔΤc scales inversely with the superconductor thickness (dS) and is zero when dS exceeds the superconducting coherence length (ξ). Here, we report a superconducting spin-valve effect involving a different underlying mechanism in which magnetization alignment and ΔΤc are determined by nodal quasiparticle excitation states on the Fermi surface of the d-wave superconductor YBa2Cu3O7-δ sandwiched between insulating layers of ferromagnetic Pr0.8Ca0.2MnO3. We observe ΔΤc values that approach 2 K with the sign of ΔΤc oscillating with dS over a length scale exceeding 100ξ and, for particular values of dS, the superconducting state reinforces an antiparallel magnetization alignment. These results pave the way to all-oxide superconducting memory in which superconductivity modulates the magnetic state.

Uniform phosphorus doping of untapered germanium nanowires.

One of the major challenges in the growth of vapor-liquid-solid (VLS) nanowires is the control of dopant incorporation in the structures. In this work, we study the n-type doping and morphology of nanowires grown by chemical vapor deposition when HCl is introduced. We obtain fully untapered nanowires with a growth temperature up to 410 °C and measure their resistivity using the 4-probe technique to be 2.0 mΩ cm. We perform energy dispersive x-ray measurements showing a concentration of dopants in the (5-7) × 1018 cm-3 range, being radially and axially uniform. The combination of these two measurements shows that the mobility is the same as for bulk germanium, demonstrating that the VLS mechanism has no detrimental effect for the electron transport in these nanowires.

Layer-by-layer assembly for biomedical applications in the last decade.

In the past two decades, the design and manufacture of nanostructured materials has been of tremendous interest to the scientific community for their application in the biomedical field. Among the available techniques, layer-by-layer (LBL) assembly has attracted considerable attention as a convenient method to fabricate functional coatings. Nowadays, more than 1000 scientific papers are published every year, tens of patents have been deposited and some commercial products based on LBL technology have become commercially available. LBL presents several advantages, such as (1): a precise control of the coating properties; (2) environmentally friendly, mild conditions and low-cost manufacturing; (3) versatility for coating all available surfaces; (4) obtainment of homogeneous film with controlled thickness; and (5) incorporation and controlled release of biomolecules/drugs. This paper critically reviews the scientific challenge of the last 10 years--functionalizing biomaterials by LBL to obtain appropriate properties for biomedical applications, in particular in tissue engineering (TE). The analysis of the state-of-the-art highlights the current techniques and the innovative materials for scaffold and medical device preparation that are opening the way for the preparation of LBL-functionalized substrates capable of modifying their surface properties for modulating cell interaction to improve substitution, repair or enhancement of tissue function.

Anterior Segment Optical Coherence Tomography in Uveitis-Glaucoma-Hyphema Syndrome.

PURPOSE: Uveitis-Glaucoma-Hyphema (UGH) syndrome results from contact between the intraocular lens (IOL) and the iris or ciliary body, leading to uveal structure erosion and blood-aqueous barrier breakdown. Treatment involves various drugs, with IOL removal often being necessary. Diagnosis relies on clinical signs, but imaging techniques like ultrasound biomicroscopy (UBM) or anterior segment optical coherence tomography (AS-OCT) are crucial. AS-OCT accurately depicts IOL position and potential contact, emerging as a primary alternative to UBM in the diagnosis. Our study aimed to correlate AS-OCT findings with clinically detectable iris atrophy in pseudophakic patients with IOL-iris chafing and UGH syndrome. METHODS: The study retrospectively analyzed patients diagnosed with UGH syndrome presenting at the Ocular Immunology Unit of Reggio Emilia, Italy, from January 2019 to August 2023. Patients' data were collected. Ophthalmological exams and imaging were performed. The peephole sign in AS-OCT images was evaluated. Statistical analyses were conducted, with a significance level of p ≤ 0.05. RESULTS: The study reviewed 22 eyes of 22 patients with UGH syndrome. Four eyes were excluded, leaving 18 patients (8 females, 10 males). Common misdiagnoses included idiopathic anterior uveitis (55.5%) and herpetic anterior uveitis (16.7%). All patients had iris transillumination defects, mostly focal (77.8%). AS-OCT revealed IOL chafing in all the eyes, with peephole sign correlation. More peephole signs occurred with IOL in the sulcus (p-value = 0.08). CONCLUSION: The study recommends AS-OCT for UGH syndrome confirmation and UBM when IOL-iris chafing is not observed on AS-OCT scans.

Reggio Emilia (Northern Italy) Interdisciplinary Uveitis Clinic: What We Have Learned in the Last 20 Years.

PURPOSE: To analyze the referral patterns and the clinical and therapeutic features of patients diagnosed with uveitis in an Italian tertiary referral center to provide a comparison with previously published series from the same center. METHODS: Retrospective retrieval of data on all new referrals to the Ocular Immunology Unit in Reggio Emilia (Italy) between November 2015 and April 2022 and comparison with previously published series from the same center. RESULTS: Among the 1557 patients, the male-to-female ratio was 1:1.27. Anterior uveitis was the most common diagnosis (53.7%), followed by posterior (21.6%), pan- (18.5%), and intermediate (6.2%) uveitis. The most identifiable specific diagnoses were anterior herpetic uveitis (18.4%), Fuchs uveitis (12.8%), and tuberculosis (6.1%). Infectious etiologies were the most frequent (34.1%) and were more diffuse among non-Caucasian patients (p < 0.001), followed by systemic disease-associated uveitis (26.5%), and ocular-specific conditions (20%). Idiopathic uveitis accounted for 19.4% of cases. Fuchs uveitis presented the longest median diagnostic delay (21 months). Immunosuppressants were administered to 25.2% of patients. Antimetabolites, calcineurin inhibitors, and biologicals were prescribed to 18.4%, 3%, and 11.4% of cases, respectively. Compared to our previous reports, we observed a significant increase in foreign-born patients and in infectious uveitis, a decrease in idiopathic conditions, and an increasing use of non-biological and biological steroid-sparing drugs. CONCLUSIONS: The patterns of uveitis in Italy have been changing over the last 20 years, very likely due to migration flows. Diagnostic improvements and a more widespread interdisciplinary approach could reduce the incidence of idiopathic uveitis as well as diagnostic delay.

Epidemiology of Pediatric Uveitis.

Uveitis is uncommon in children and its diagnosis and treatment are challenging. Little is known of the epidemiology of pediatric uveitis. Indeed, population-based studies in the literature are rare. However, there are many tertiary referral center reports that describe the patterns of uveitis in childhood, although few are from developed countries, and their comparison presents some issues. Anterior uveitis is the most frequent entity worldwide, especially in Western countries, where juvenile idiopathic arthritis is diffuse. Most cases of intermediate uveitis do not show any association with infectious or noninfectious systemic diseases. In low- and middle-income countries, posterior uveitis and panuveitis are prevalent due to the higher rates of infectious etiologies and systemic diseases such as Behçet disease and Vogt-Koyanagi-Harada disease. In recent decades, idiopathic uveitis rate has decreased thanks to diagnostic improvements.

Effectiveness of Pegylated Interferon Alpha-2a in Post-Uveitic Macular Edema Previously Responding to Non-Pegylated Interferon.

PURPOSE: To evaluate the efficacy of pegylated interferon (PEG-IFN) alpha-2a to treat post-uveitic relapsing macular edema (ME) after withdrawal of non-PEG IFN alpha-2a or 2b to maintain treatment efficacy. METHODS: This retrospective study investigated subjects with post-uveitic ME who received weekly subcutaneous PEG-IFN alpha-2a injections. Comparisons between baseline central macular thickness (CMT) and best-corrected visual acuity (BCVA) and those at all follow-up visits were made. RESULTS: Six patients (nine eyes) were treated and followed up for six months. CMT (mean [standard deviation]) decreased from 375[117] to 283[39] µm after one month (p < 0.001), remaining significantly lower up to the final follow-up visit at six months (275[38] µm, p = 0.008), and BCVA (0.21[0.16] logMAR at baseline) showed an improvement of 0.12[0.11] logMAR (p = 0.026) at six months. Neither recurrences nor any serious adverse events were recorded. CONCLUSIONS: Post-uveitic ME patients were effectively and safely treated with PEG-IFN alpha-2a.

Hidden defects in silicon nanowires.

Recent publications have reported the presence of hexagonal phases in Si nanowires. Most of these reports were based on 'odd' diffraction patterns and HRTEM images­'odd' means that these images and diffraction patterns could not be obtained on perfect silicon crystals in the classical diamond cubic structure. We analyze the origin of these 'odd' patterns and images by studying the case of various Si nanowires grown using either Ni or Au as catalysts in combination with P or Al doping. Two models could explain the experimental results: (i) the presence of a hexagonal phase or (ii) the presence of defects that we call 'hidden' defects because they cannot be directly observed in most images. We show that in many cases one direction of observation is not sufficient to distinguish between the two models. Several directions of observations have to be used. Secondly, conventional TEM images, i.e. bright-field two-beam and dark-field images, are of great value in the identification of 'hidden' defects. In addition, slices of nanowires perpendicular to the growth axis can be very useful. In the studied nanowires no hexagonal phase with long range order is found and the 'odd' images and diffraction patterns are mostly due to planar defects causing superposition of different crystal grains. Finally, we show that in Raman experiments the defect-rich NWs can give rise to a Raman peak shifted to 504­511 cm⁻¹ with respect to the Si bulk peak at 520 cm⁻¹, indicating that Raman cannot be used to identify a hexagonal phase.

Effect of HCl on the doping and shape control of silicon nanowires.

The introduction of hydrogen chloride during the in situ doping of silicon nanowires (SiNWs) grown using the vapor-liquid-solid (VLS) mechanism was investigated. Compared with non-chlorinated atmospheres, the use of HCl with dopant gases considerably improves the surface morphology of the SiNWs, leading to extremely smooth surfaces and a greatly reduced tapering. Variations in the wire diameter are massively reduced for boron doping, and cannot be measured at 600 °C for phosphorous over several tens of micrometers. This remarkable feature is accompanied by a frozen gold migration from the catalyst, with no noticeable levels of gold clusters observed using scanning electron microscopy. A detailed study of the apparent resistivity of the NWs reveals that the dopant incorporation is effective for both types of doping. A graph linking the apparent resistivity to the dopant to silane dilution ratio is built for both types of doping and discussed in the frame of the previous results.

Processing and characterization of innovative scaffolds for bone tissue engineering.

A new protocol, based on a modified replication method, is proposed to obtain bioactive glass scaffolds. The main feature of these samples, named "shell scaffolds", is their external surface that, like a compact and porous shell, provides both high permeability to fluids and mechanical support. In this work, two different scaffolds were prepared using the following slurry components: 59 % water, 29 % 45S5 Bioglass(®) and 12 % polyvinylic binder and 51 % water, 34 % 45S5 Bioglass(®), 10 % polyvinylic binder and 5 % polyethylene. All the proposed samples were characterized by a widespread microporosity and an interconnected macroporosity, with a total porosity of 80 % vol. After immersion in a simulated body fluid (SBF), the scaffolds showed strong ability to develop hydroxyapatite, enhanced by the high specific surface of the porous systems. Moreover preliminary biological evaluations suggested a promising role of the shell scaffolds for applications in bone tissue regeneration. As regards the mechanical behaviour, the shell scaffolds could be easily handled without damages, due to their resistant external surface. More specifically, they possessed suitable mechanical properties for bone regeneration, as proved by compression tests performed before and after immersion in SBF.

Platelet-rich plasma and blood components for non-transfusion use: technical and medicolegal aspects.

There are a large number of publications describing the use of platelet-rich plasma (PRP) in multiple fields of application. These illustrate a large number of therapeutic elements with different and specific actions within 'platelet gel' (this term is used in the current regulations to define this product). This term, however, lacks specificity and, depending on the method used in its production is variable both in its blood composition and in platelet concentration, and several publications consider better and easier methods of platelet gel production, which may or may not lead to greater standardization in the product. The authors illustrate the general aspects of PRP and other blood components for non-transfusion use, briefly touching on the history and different fields of application and the rational of for its use. Given the increased use of such preparations, the authors describe critically the regulations in force in Europe and propose a new regulatory framework aimed to simplify and facilitate the use of such material as a therapeutic agent within medicine.

Characterization of the Shells in Layer-By-Layer Nanofunctionalized Particles: A Computational Study.

Drug delivery carriers are considered an encouraging approach for the localized treatment of disease with minimum effect on the surrounding tissue. Particularly, layer-by-layer releasing particles have gained increasing interest for their ability to develop multifunctional systems able to control the release of one or more therapeutical drugs and biomolecules. Although experimental methods can offer the opportunity to establish cause and effect relationships, the data collection can be excessively expensive or/and time-consuming. For a better understanding of the impact of different design conditions on the drug-kinetics and release profile, properly designed mathematical models can be greatly beneficial. In this work, we develop a continuum-scale mathematical model to evaluate the transport and release of a drug from a microparticle based on an inner core covered by a polymeric shell. The present mathematical model includes the dissolution and diffusion of the drug and accounts for a mechanism that takes into consideration the drug biomolecules entrapped into the polymeric shell. We test a sensitivity analysis to evaluate the influence of changing the model conditions on the total system behavior. To prove the effectiveness of this proposed model, we consider the specific application of antibacterial treatment and calibrate the model against the data of the release profile for an antibiotic drug, metronidazole. The results of the numerical simulation show that ∼85% of the drug is released in 230 h, and its release is characterized by two regimes where the drug dissolves, diffuses, and travels the external shell layer at a shorter time, while the drug is released from the shell to the surrounding medium at a longer time. Within the sensitivity analysis, the outer layer diffusivity is more significant than the value of diffusivity in the core, and the increase of the dissolution parameters causes an initial burst release of the drug. Finally, changing the shape of the particle to an ellipse produces an increased percentage of drugs released with an unchanged release time.

The importance of the radial growth in the faceting of silicon nanowires.

The state of the lateral surface plays a great role in the physics of silicon nanowires. Surprisingly, little is known about the phenomena that occur during growth on the facets of the wires. We demonstrate here that the size and shape of the facets evolve with the exposure time and the radial growth speed. Depending on the chemistry of the surface, either passivated by chlorine or decorated by gold clusters, the radial growth speed varies and the evolution of the facets is enhanced or impeded. If the radial growth speed is high enough, the faceting of the wire can change from top to bottom due to the exposure time difference. Three types of faceting are exposed, dodecagonal, hexagonal, and triangular. An evolution model is introduced to link the different faceting structures and the possible transitions.

Surface recombination velocity measurements of efficiently passivated gold-catalyzed silicon nanowires by a new optical method.

The past decade has seen the explosion of experimental results on nanowires grown by catalyzed mechanisms. However, few are known on their electronic properties especially the influence of surfaces and catalysts. We demonstrate by an optical method how a curious electron-hole thermodynamic phase can help to characterize volume and surface recombination rates of silicon nanowires (SiNWs). By studying the electron-hole liquid dynamics as a function of the spatial confinement, we directly measured these two key parameters. We measured a surface recombination velocity of passivated SiNWs of 20 cm s(-1), 100 times lower than previous values reported. Furthermore, the volume recombination rate of gold-catalyzed SiNWs is found to be similar to that of a high-quality three-dimensional silicon crystal; the influence of the catalyst is negligible. These results advance the knowledge of SiNW surface passivation and provide essential guidance to the development of efficient nanowire-based devices.

New trends in breast reconstructive surgery: "Florentine Lily" reductive mastoplasty.

BACKGROUND: To describe a mammoplasty technique that we called "Florentine Lily" because of the shape of the pre-operative drawings similarity with the symbol lily Florentine. METHODS: In a group of 190 women who underwent reductive mammoplasty, 23 women affected by severe enlarged breasts were selected. Main selection requirements were: 18-30 cm rising of the Areola-Nipple Complex (NAC). RESULTS: to obtain a functional and cosmetic result; preservation of mammary gland function; vitality of the areola-nipple complex and its sensitivity. We describe the case of 35 years old woman affected by severe enlargement of the breast and no pathologies. CONCLUSION: We didn't observe necrosis of the skin flaps and NAC in any case. In one case (rising of Nipple-Areola Complex >25 cm) NAC showed NAC 2 days post-surgery, which spontaneously resolved. Minor complications (edema and ematoma) developed in 20 cases. No infections were observed.

Recombination dynamics of spatially confined electron-hole system in luminescent gold catalyzed silicon nanowires.

We study by time-resolved low temperature photoluminescence (PL) experiments of the electronic states of silicon nanowires (SiNWs) grown by gold catalyzed chemical vapor deposition and passivated by thermal SiO(2). The typical recombination line of free carriers in gold-catalyzed SiNWs (Au-SiNWs) is identified and studied by time-resolved experiments. We demonstrate that intrinsic Auger recombination governs the recombination dynamic of the dense e-h plasma generated inside the NW. In a few tens of nanoseconds after the pulsed excitation, the density of the initial electronic system rapidly decreases down to reach that of a stable electron-hole liquid phase. The comparison of the PL intensity decay time of Au-SiNWs with high crystalline quality and purity silicon layer allows us to conclude that the Au-SiNW electronic properties are highly comparable to those of bulk silicon crystal.

Fibroadenoma in the bilateral accessory axillary breast.

The authors treated a case of bilateral accessory axillary breast tissue. Excision with histologic examination confirmed the diagnosis of fibroadenoma. Treatment left the woman with incision scars (3.5 cm) in the axillary pyramid, a location often not seen during a patient's normal movements. Thus, despite a minor aesthetic incision, gives the advantage of complete histologic analysis was gained. Liposuction treatment was used in this case. The scar results were good.

The effects of HCl on silicon nanowire growth: surface chlorination and existence of a 'diffusion-limited minimum diameter'.

Silicon nanowires were grown by chemical vapour deposition on gold catalysts using SiH4 and HCl diluted in H2. The effects of HCl on the wires and the catalysts were investigated for various HCl partial pressures. Keeping all other parameters constant, gold migration on the silicon surface is found to be dramatically reduced by the surface chlorination induced by HCl. We then use HCl to control gold migration and show the existence of a 'diffusion-limited minimum diameter'. This diameter limit arises from the surface migration kinetics and it sets a lower bound on the wire diameter distribution.

The morphology of silicon nanowires grown in the presence of trimethylaluminium.

The effects of trimethylaluminium (TMA) on silicon nanowires grown by chemical vapour deposition (CVD) were investigated in the 650-850 degrees C growth temperature range. Gold was used as the growth catalyst and SiH4 in H2 carrier gas as the Si precursor. Depending on substrate temperature and TMA partial pressure, the structure's morphology evolves from wires to tapered needles, pyramids or nanotrees. The TMA presence was linked to two specific growth modes: an enhanced surface growth which forms Si needles and a branched growth leading to Si nanotrees. We suggest that competition between these two specific growth modes and the usual Au-catalyzed VLS growth is responsible for the observed morphology changes.