Enhanced Fano resonances in a silicon nitride photonic crystal nanobeam-assisted micro ring resonator for dual telecom band operation.

Silicon-based Micro Ring Resonators (MRR) are a powerful tool for the realization of label free optical biosensors. The sharp edge of a Fano resonance in a Silicon Nitride (Si3N4) platform can boost photonic sensing applications based on MRRs. In this work, we demonstrate enhanced Fano resonance features for a Si3N4 Micro Ring Resonator assisted by a Photonic Crystal Nanobeam (PhCN-MRR) operating in the TM-like mode at the O-band wavelengths. Our findings show that the fabricated PhCN-MRR results in increased asymmetric resonances for TM-like mode compared with TE-like mode operation in the C-band. As a result, a versatile and flexible design to realize Fano resonance with polarization dependent asymmetry in the C and O telecom bands is presented.

Link budget analysis of bi-directional LEO and GEO optical feeder links advancing the beam wander model's accuracy.

The telecommunications of the future rely on the concept of a three-dimensional architecture able to integrate terrestrial and non-terrestrial networks with the goal to ensure a reliable and high-speed connectivity to users located anywhere. In this context, free space optical communications constitute a candidate technology for feeder links, thanks to their advantages in terms of bandwidth and achievable data rates. Nonetheless, due to the propagation impediments encountered by an optical beam travelling through atmosphere, flexible and accurate instruments able to support the design of optical feeder links are needed. Therefore, in this paper a link budget numerical tool able to meet these requirements is presented and the link budget analysis for real optical feeder links is performed demonstrating its prediction accuracy by means of the comparison with experimental results for both low Earth orbit and geostationary Earth orbit based configurations. Finally, the limits of the conventional beam wander model are analyzed and overcome.

Compact angled multimode interference duplexers for multi-gas sensing applications.

A compact, low-loss 2 × 1 angled-multi-mode-interference-based duplexer is proposed as an optical component for integrating several wavelengths with high coupling efficiency. The self-imaging principle in multimode waveguides is exploited to combine two target wavelengths, corresponding to distinctive absorption lines of important trace gases. The device performance has been numerically enhanced by engineering the geometrical parameters, offering trade-offs in coupling efficiency ratios. The proposed designs are used as versatile duplexers for detecting gas combinations such as ammonia-methane, ammonia-ethane, and ammonia-carbon dioxide, enabling customization for specific sensing applications. The duplexers designed are then fabricated and characterized, with a special focus on assessing the impact of the different target wavelengths on coupling efficiency.

Highly efficient and selective integrated directional couplers for multigas sensing applications.

The design and fabrication of a compact, low-loss, broadband directional coupler (DC) based duplexer operating in the near-infrared (NIR) region are demonstrated. The duplexer exhibits high selectivity and coupling efficiency (CE), for target wavelengths of 1530 nm and 1653.7 nm, making it applicable in systems for the multi-gas detection of ammonia and methane. The measured CE for the duplexer is 73% and 76% at 1530 nm and 1653.7 nm respectively. These results demonstrate the effectiveness of the duplexer as a broadband and scalable power source for highly sensitive sensing techniques, like quartz-enhanced photoacoustic spectroscopy (QEPAS). Its compact size and low-loss characteristics make it highly portable and well-suited for drone-based multi-gas detection applications.

Unlocking the monolithic integration scenario: optical coupling between GaSb diode lasers epitaxially grown on patterned Si substrates and passive SiN waveguides.

Silicon (Si) photonics has recently emerged as a key enabling technology in many application fields thanks to the mature Si process technology, the large silicon wafer size, and promising Si optical properties. The monolithic integration by direct epitaxy of III-V lasers and Si photonic devices on the same Si substrate has been considered for decades as the main obstacle to the realization of dense photonics chips. Despite considerable progress in the last decade, only discrete III-V lasers grown on bare Si wafers have been reported, whatever the wavelength and laser technology. Here we demonstrate the first semiconductor laser grown on a patterned Si photonics platform with light coupled into a waveguide. A mid-IR GaSb-based diode laser was directly grown on a pre-patterned Si photonics wafer equipped with SiN waveguides clad by SiO2. Growth and device fabrication challenges, arising from the template architecture, were overcome to demonstrate more than 10 mW outpower of emitted light in continuous wave operation at room temperature. In addition, around 10% of the light was coupled into the SiN waveguides, in good agreement with theoretical calculations for this butt-coupling configuration. This work lift an important building block and it paves the way for future low-cost, large-scale, fully integrated photonic chips.

Investigation of the Properties of 316L Stainless Steel after AM and Heat Treatment.

Additive manufacturing, including laser powder bed fusion, offers possibilities for the production of materials with properties comparable to conventional technologies. The main aim of this paper is to describe the specific microstructure of 316L stainless steel prepared using additive manufacturing. The as-built state and the material after heat treatment (solution annealing at 1050 °C and 60 min soaking time, followed by artificial aging at 700 °C and 3000 min soaking time) were analyzed. A static tensile test at ambient temperature, 77 K, and 8 K was performed to evaluate the mechanical properties. The characteristics of the specific microstructure were examined using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The stainless steel 316L prepared using laser powder bed fusion consisted of a hierarchical austenitic microstructure, with a grain size of 25 µm as-built up to 35 µm after heat treatment. The grains predominantly contained fine 300-700 nm subgrains with a cellular structure. It was concluded that after the selected heat treatment there was a significant reduction in dislocations. An increase in precipitates was observed after heat treatment, from the original amount of approximately 20 nm to 150 nm.

Design of optically transparent metasurfaces based on CVD graphene for mmWave applications.

We propose and numerically investigate a smart, optically transparent digital metasurface reflective in the mmWave range, based on CVD graphene programmable elements. For both TM and TE polarizations, we detail the optimization of the unit cells, designed to exhibit two distinct states that correspond to those of binary encoding. The whole metasurface encoding can be customized to provide different electromagnetic functions, such as wide-band beam splitting at a controlled angle and reduction of the Radar Cross Section. Optically transparent metasurfaces could be integrated and exploited in windows and transparent surfaces in future Beyond-5G and 6G ecosystems.

Safety profile of treatment with greenlight versus Thulium Laser for benign prostatic hyperplasia.

OBJECTIVE: The major strengths of surgical treatment of benign prostatic hyperplasia with laser are reduced morbidity compared to endoscopic resection. No studies analysed the different risk of intra/peri-operative events between patients undergoing Thulium and GreenLight procedures. MATERIALS AND METHODS: We retrospectively reviewed 100 consecutive cases undergoing GreenLight vaporization and Thulium procedures performed during the learning curve of two expert endoscopic surgeons. Pre-operative data, intra and post-operative events at 90 days were analysed. RESULTS: Patients on antiplatelet/anticoagulant therapy were pre-dominant in the Green group (p < 0.0001). Rates of blood transfusion (p < 0.0038), use of resectoscope (p < 0.0086), and transient stress urinary incontinence were statistically higher in the Thulium group. On the contrary conversions to TURP (p < 0.023) were more frequent in GreenLight patients. Readmissions were more frequently necessary in GreenLight group (24%) vs. Thulium group (26.6%). The overall complication rate in GreenLight and Thulium groups were 31% and 53% respectively; Clavien 3b complications were 13% in Thulium patients versus 1% in GreenLight patients. CONCLUSIONS: GreenLight and Thulium treatments show similar safety profiles. Randomized controlled trial are needed to better clarify the rate of major complications in Thulium group, and the incidence of post-operative storage symptoms in these patients' populations.

Design and Fabrication of a Flexible Gravimetric Sensor Based on a Thin-Film Bulk Acoustic Wave Resonator.

Sensing systems are becoming less and less invasive. In this context, flexible materials offer new opportunities that are impossible to achieve with bulky and rigid chips. Standard silicon sensors cannot be adapted to curved shapes and are susceptible to big deformations, thus discouraging their use in wearable applications. Another step forward toward minimising the impacts of the sensors can be to avoid the use of cables and connectors by exploiting wireless transmissions at ultra-high frequencies (UHFs). Thin-film bulk acoustic wave resonators (FBARs) represent the most promising choice among all of the piezoelectric microelectromechanical system (MEMS) resonators for the climbing of radio frequencies. Accordingly, the fabrication of FBARs on flexible and wearable substrates represents a strategic step toward obtaining a new generation of highly sensitive wireless sensors. In this work, we propose the design and fabrication of a flexible gravimetric sensor based on an FBAR on a polymeric substrate. The resonator presents one of the highest electromechanical coupling factors in the category of flexible AlN-based FBARs, equal to 6%. Moreover, thanks to the polymeric support layer, the presence of membranes can be avoided, which leads to a faster and cheaper fabrication process and higher robustness of the structure. The mass sensitivity of the device was evaluated, obtaining a promising value of 23.31 ppm/pg. We strongly believe that these results can pave the way to a new class of wearable MEMS sensors that exploit ultra-high-frequency (UHF) transmissions.

Wearable Heart Rate Monitoring Device Communicating in 5G ISM Band for IoHT.

Advances in wearable device technology pave the way for wireless health monitoring for medical and non-medical applications. In this work, we present a wearable heart rate monitoring platform communicating in the sub-6GHz 5G ISM band. The proposed device is composed of an Aluminium Nitride (AlN) piezoelectric sensor, a patch antenna, and a custom printed circuit board (PCB) for data acquisition and transmission. The experimental results show that the presented system can acquire heart rate together with diastolic and systolic duration, which are related to heart relaxation and contraction, respectively, from the posterior tibial artery. The overall system dimension is 20 mm by 40 mm, and the total weight is 20 g, making this device suitable for daily utilization. Furthermore, the system allows the simultaneous monitoring of multiple subjects, or a single patient from multiple body locations by using only one reader. The promising results demonstrate that the proposed system is applicable to the Internet of Healthcare Things (IoHT), and particularly Integrated Clinical Environment (ICE) applications.

Evaluation of Powder Metallurgy Workpiece Prepared by Equal Channel Angular Rolling.

The aim of the article is to examine the workability of sintered powder material of aluminum alloy (Alumix 321) through severe plastic deformations under the conditions of the equal channel angular rolling (ECAR) process. Accordingly, the stress-strain analysis of the ECAR was carried out through a computer simulation using the finite element method (FEM) by Deform 3D software. Additionally, the formability of the ALUMIX 321 was investigated using the diametrical compression (DC) test, which was measured and analyzed by digital image correlation and finite element simulation. The relationship between failure mode and stress state in the ECAR process and the DC test was quantified using stress triaxiality and Lode angle parameter. It is concluded that the sintered powder material during the ECAR processing failure by a shearing fracture because in the fracture location the stress conditions were close to the pure shear (η and θ¯ ≈ 0). Moreover, the DC test revealed the potential role as the method of calibration of the fracture locus for stress conditions between the pure shear and the axial symmetry compression.

Congenital cysts of the lower male genitourinary tract: a disorder with various treatment approaches and pitfalls-case report.

BACKGROUND: The cysts of the male pelvic floor represent a rare clinical entity. Their origin is linked to an altered development of paramesonephric and mesonephric ducts during embryogenesis. CASE PRESENTATION: We report our experience regarding two patients presenting cysts of the ejaculatory system treated with open and mini-invasive surgery. The patients referred to our clinic with nonspecific symptoms and the diagnosis was obtained by radiological investigations. The patient treated with an open approach developed a pelvic purulent collection and a fistula of the prostatic urethra, managed with surgical drainage and prolonged bladder catheterization. On the other hand, the patient treated with laparoscopic approach did not develop any complications. No sexual or ejaculatory disorders were reported. CONCLUSIONS: Patients with congenital cysts of the pelvic floor must be adequately informed about the risks and benefits of surgery and a careful counseling is mandatory before surgery. Treatment is recommended for symptomatic patients and an endoscopic approach is associated with a high rate of recurrence. A laparoscopic approach, when possible, is desirable.

High-Q asymmetrically cladded silicon nitride 1D photonic crystals cavities and hybrid external cavity lasers for sensing in air and liquids.

In this paper we show a novel design of high Q-factor silicon nitride (SiN) 1D photonic crystal (PhC) cavities side-coupled to curved waveguides, operating with both silica and air cladding. The engineering of the etched 1D PhC cavity sidewalls angle allows for high Q-factors over a wide range of upper cladding compositions, and the achievement of the highest calculated Q-factor for non-suspended asymmetric SiN PhC structures. We show the employment of these type of SiN PhC cavities in hybrid external cavity laser (HECL) configuration, with mode-hop free single mode laser operation over a broad range of injected currents (from 25 mA to 65 mA), milliwatts of power output (up to 9 mW) and side-mode suppression ratios in the range of 40 dB. We demonstrate the operation of these devices as compact and energy efficient optical sensors that respond to refractive index changes in the surrounding medium the measurement of sodium chloride (from 0% to 25%) and sucrose (from 0% to 25%) in aqueous solution. In HECL configuration, the RI sensor exhibits a 2 orders of magnitude improvement in detection limit compared to the passive microcavity. We also discuss the possibility for applying these devices as novel transducers for refractive index changes that are induced by analyte specific absorption of infrared radiation by the target analytes present in gas or liquid phase.

Percutaneous and endoscopic combined treatment of bladder and renal lithiasis in mitrofanoff conduit

ABSTRACT Introduction and Objectives: Treatment of bulky lithiasis in continent and non-continent urine storage reservoirs has been widely described and debated (1). Less is known about the optimal treatment in patients with a Mitrofanoff conduit. If voiding in these patients is incomplete, leading to recurrent symptomatic bacteriuria, formation of large lithiasis can be a common long-term complication (2, 3). Materials and Methods: This video describes a 19-year-old woman who underwent major open surgery at the age of six, with the configuration of a continent intestinal reservoir with a Mitrofanoff conduit. In 2020, she was referred to our center with a large stone in the reservoir and a minor stone in the inferior left renal calyx. We decided to proceed using a percutaneous approach with an "endovision technique" puncture for the bladder stone, combined with a retrograde intrarenal surgery for the renal stone. The MIP System "M size" was used to perform the percutaneous procedure, thus allowing a single-step dilation. The puncture and the dilation were followed endoscopically with a flexible ureterorenoscope avoiding the use of x-rays. The procedure was carried out as follows. The first step consisted in the insertion of a hydrophilic guidewire through the Mitrofanoff conduit. A flexible ureterorenoscope was then inserted coaxial to the guidewire. The percutaneous puncture, using an 80G needle, was followed endoscopically. Two guidewires were inserted, the first as a safety guidewire and the second for the tract dilation. The "single-step" dilation technique using the MIP system was performed and followed endoscopically. For the bladder lithotripsy, a dual-action lithotripter that combines ultrasonic and mechanical energy was used. Finally, a flexible ureterorenoscope and a basket for the retrieval of a single inferior caliceal stone were used. The procedure ended after positioning a single J stent in the left kidney and a nephrostomy tube in the reservoir. Results: The operative time was 80 minutes and the fluoroscopy time was 6 seconds. Hemoglobin and creatinine serum levels remained stable after the procedure and the patient was discharged on the third post-operative day, after removing both the single J and the nephrostomy tube. Follow-up lasted 12 months, with no bladder or renal stone recurrence, maintaining good continence of the Mitrofanoff conduit. Conclusion: In patients who have undergone several major surgeries a mini-invasive approach is advisable, not only for the morbidity of an open approach, but also for the increased risk of complications while handling an intestinal reservoir. Regarding a pure endoscopic approach, the passage of a nephroscope or a cystoscope through the Mitrofanoff conduit, combined with the continuous traction during the lithotripsy, could damage and compromise its continence. For this reason, the percutaneous approach is the most suitable method in these specific and rare cases.

Holographic Manipulation of Nanostructured Fiber Optics Enables Spatially-Resolved, Reconfigurable Optical Control of Plasmonic Local Field Enhancement and SERS.

Integration of plasmonic structures on step-index optical fibers is attracting interest for both applications and fundamental studies. However, the possibility to dynamically control the coupling between the guided light fields and the plasmonic resonances is hindered by the turbidity of light propagation in multimode fibers (MMFs). This pivotal point strongly limits the range of studies that can benefit from nanostructured fiber optics. Fortunately, harnessing the interaction between plasmonic modes on the fiber tip and the full set of guided modes can bring this technology to a next generation progress. Here, the intrinsic wealth of information of guided modes is exploited to spatiotemporally control the plasmonic resonances of the coupled system. This concept is shown by employing dynamic phase modulation to structure both the response of plasmonic MMFs on the plasmonic facet and their response in the corresponding Fourier plane, achieving spatial selective field enhancement and direct control of the probe's work point in the dispersion diagram. Such a conceptual leap would transform the biomedical applications of holographic endoscopic imaging by integrating new sensing and manipulation capabilities.

Effective hole conductivity in nitrogen-doped CVD-graphene by singlet oxygen treatment under photoactivation conditions.

Nitrogen substitutional doping in the π-basal plane of graphene has been used to modulate the material properties and in particular the transition from hole to electron conduction, thus enlarging the field of potential applications. Depending on the doping procedure, nitrogen moieties mainly include graphitic-N, combined with pyrrolic-N and pyridinic-N. However, pyridine and pyrrole configurations of nitrogen are predominantly introduced in monolayer graphene:N lattice as prepared by CVD. In this study, we investigate the possibility of employing pyridinic-nitrogen as a reactive site as well as activate a reactive center at the adjacent carbon atoms in the functionalized C-N bonds, for additional post reaction like oxidation. Furthermore, the photocatalytic activity of the graphene:N surface in the production of singlet oxygen (1O2) is fully exploited for the oxidation of the graphene basal plane with the formation of pyridine N-oxide and pyridone structures, both having zwitterion forms with a strong p-doping effect. A sheet resistance value as low as 100 Ω/□ is reported for a 3-layer stacked graphene:N film.

Design of vanadium-dioxide-based resonant structures for tunable optical response.

Phase change materials are suitable for tunable photonic devices where the optical response can be altered under external stimuli, such as heat, an electrical or an optical signal. In this scenario, we performed numerical simulations to study the optical properties of a flat unpatterned resonant structure and a grating, both coated with a thin film of vanadium dioxide (VO2). Our results suggest that it is possible to modulate broadband and narrowband reflectance spectra of the resonant structures in the visible to near-infrared range by more than 40 % when the VO2 undergoes an insulator-to-metal phase transition. Resonant devices with a tunable spectral response may find application in sensors, filters, absorbers, and detectors.

Percutaneous and endoscopic combined treatment of bladder and renal lithiasis in mitrofanoff conduit.

INTRODUCTION AND OBJECTIVES: Treatment of bulky lithiasis in continent and non-continent urine storage reservoirs has been widely described and debated (1). Less is known about the optimal treatment in patients with a Mitrofanoff conduit. If voiding in these patients is incomplete, leading to recurrent symptomatic bacteriuria, formation of large lithiasis can be a common long-term complication (2, 3). MATERIALS AND METHODS: This video describes a 19-year-old woman who underwent major open surgery at the age of six, with the configuration of a continent intestinal reservoir with a Mitrofanoff conduit. In 2020, she was referred to our center with a large stone in the reservoir and a minor stone in the inferior left renal calyx. We decided to proceed using a percutaneous approach with an "endovision technique" puncture for the bladder stone, combined with a retrograde intrarenal surgery for the renal stone. The MIP System "M size" was used to perform the percutaneous procedure, thus allowing a single-step dilation. The puncture and the dilation were followed endoscopically with a flexible ureterorenoscope avoiding the use of x-rays. The procedure was carried out as follows. The first step consisted in the insertion of a hydrophilic guidewire through the Mitrofanoff conduit. A flexible ureterorenoscope was then inserted coaxial to the guidewire. The percutaneous puncture, using an 80G needle, was followed endoscopically. Two guidewires were inserted, the first as a safety guidewire and the second for the tract dilation. The "single-step" dilation technique using the MIP system was performed and followed endoscopically. For the bladder lithotripsy, a dual-action lithotripter that combines ultrasonic and mechanical energy was used. Finally, a flexible ureterorenoscope and a basket for the retrieval of a single inferior caliceal stone were used. The procedure ended after positioning a single J stent in the left kidney and a nephrostomy tube in the reservoir. RESULTS: The operative time was 80 minutes and the fluoroscopy time was 6 seconds. Hemoglobin and creatinine serum levels remained stable after the procedure and the patient was discharged on the third post-operative day, after removing both the single J and the nephrostomy tube. Follow-up lasted 12 months, with no bladder or renal stone recurrence, maintaining good continence of the Mitrofanoff conduit. CONCLUSION: In patients who have undergone several major surgeries a mini-invasive approach is advisable, not only for the morbidity of an open approach, but also for the increased risk of complications while handling an intestinal reservoir. Regarding a pure endoscopic approach, the passage of a nephroscope or a cystoscope through the Mitrofanoff conduit, combined with the continuous traction during the lithotripsy, could damage and compromise its continence. For this reason, the percutaneous approach is the most suitable method in these specific and rare cases.

MIG and TIG Joining of AA1070 Aluminium Sheets with Different Surface Preparations.

In this work, AA1070 aluminium alloy sheets are joined using TIG and MIG welding after three different edge preparations. Shearing, water jet and plasma-cut processes were used to cut sheets, subsequently welded using ER5356 and ER4043 filler metals for TIG and MIG, respectively. Mechanical properties of the obtained sheets were assessed through tensile tests obtaining a relation between sheet preparation and welding tightness. Micro-hardness measures were performed to evaluate the effects of both welding and cutting processes on the micro-hardness of the alloy, highlighting that TIG welding gives rise to inhomogeneous micro-hardness behaviour. After tensile tests, surface fractures were observed employing scanning electron microscopy to highlight the relation between tensile properties and edge preparations. Fractures show severe oxidation in the water jet cut specimens, ductile fractures and gas porosities.

Recent Advances in Multi-Functional Coatings for Soft Magnetic Composites.

During the past 50 years, the aim to reduce the eddy current losses in magnetic cores to a minimum led to the formulation of new materials starting from electrically insulated iron powders, today called Soft Magnetic Composites (SMC). Nowadays, this promising branch of materials is still held back by the mandatory tradeoff between energetic, electrical, magnetic, and mechanical performances. In most cases, the research activity focuses on the deposition of an insulating/binding layer, being one of the critical points in optimizing the final composite. This insulation usually is achieved by either inorganic or organic layer constituents. The main difference is the temperature limit since most inorganic materials typically withstand higher treatment temperatures. As a result, the literature shows many materials and process approaches, each one designed to meet a specific application. The present work summarizes the recent advances in state of the art, analyzing the relationship among material compositions and magnetic and mechanical properties. Each coating shows its own processing sets, which vary from simple mechanical mixing to advanced chemical methods to metallurgical treatments. From state of the art, Aluminum coatings are characterized by higher current losses and low mechanical properties. In contrast, higher mechanical properties are obtained by adopting Silicon coatings. The phosphates coatings show the best-balanced overall properties. Each coating type was thoroughly investigated and then compared with the literature background highlighting. The present paper thus represents a critical overview of the topic that could serve as a starting point for the design and development of new and high-performing coating solutions for SMCs. However, global research activity continuously refines the recipes, introducing new layer materials. The following steps and advances will determine whetherthese materials breakthrough in the market.