Surface elasticity based nonlocal vibration analysis of bidirectional functionally graded tapered nanobeam

The present paper proposes the impact of the mutual interplay of nonuniform geometry with surface and nonlocal stresses on the vibration characteristics of bi-directional functionally graded tapered nanobeam with surface layers. The material composition of nanobeam is assumed to follow a power-law distribution along the thickness and exponential along the length. The nonuniformity in the geometry of nanobeam arises due to the linear variation of thickness along its length. The considered nanobeam is modeled as a Timoshenko nanobeam with surface layers of negligible thickness. The nonlocal and surface effects are incorporated using Eringen's nonlocal theory with Gurtin-Murdoch's surface elasticity theory. Hamilton's energy principle is employed to derive the nonlocal equations of motion with boundary conditions. The differential quadrature method is exploited to obtain the natural frequencies and the convergence of the method is demonstrated. A parametric study is introduced to investigate the influence of critical parameters such as taper parameter, surface parameter and nonlocal parameter on the vibration characteristics of bi-directionally graded nanobeam. This work explains that the nonuniformity in the geometry of nanobeam significantly influences the frequency range of tapered nanobeam with surface layers. These results will serve as a benchmark for future work on nonuniform nanostructures

Lurie networks with k-contracting dynamics

This paper proposes an approach to enable the weights and biases of a novel neural ODE, the Lurie network, to be trained in such a manner that a generalised concept of stability is guaranteed. This generalised stability measure is derived through the use of k-contraction analysis, which guarantees global convergence to a point, line or plane in the neural state-space. An unconstrained parametrisation of this condition is derived, allowing models to be trained using standard optimisation algorithms, whilst limiting the search space to solutions satisfying the k-contraction constraint. The novel stability result and parametrisation provide a toolset for training over the space of Lurie network's which exhibit the convergent behaviours observed during neural computation in the brain. For example, global convergence to one of multiple equilibrium points or limit cycles are properties observed in associative and working memory

On-Chip Er: Ta2O5 optical pulse amplifier

Erbium ions doped in tantalum pentoxide (Er:Ta2O5) offer a promising foundation for achieving efficient optical amplification of telecommunication signals in photonic integrated circuits (PICs). In this paper, an on-chip Er:Ta2O5 waveguide optical pulse amplifier operating at 1550 nm wavelength band (C-band) is reported. Silica-clad Er: Ta2O5 rib waveguides were fabricated using RF magnetron sputtered film patterned by photolithography and dry-etched by Ar-ion beam milling. On-chip amplification of continuous wave (CW) and pulsed signals in C-band were demonstrated. Furthermore, the Er: Ta2O5 chip was evaluated for real-time optical communication by transmitting data streams in baseband and radio-over-fiber (RoF) schemes. The transmitted data was decoded and processed to determine the bit error rate (BER). The low BER values highlight the potential of the Er: Ta2O5 platform for high-speed optical communication applications

Update on the role of bone turnover markers in the diagnosis and management of osteoporosis: a consensus paper from The European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), International Osteoporosis Foundation (IOF), and International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)

Purpose: the International Osteoporosis Foundation (IOF) and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) have proposed procollagen type I N propeptide (PINP) and β isomerized C-terminal telopeptide of type I collagen (β-CTX-I) as reference bone turnover markers (BTMs) for osteoporosis. This report examines the published literature since the 2011 IOF-IFCC position paper in order to determine the clinical potential of the reference BTMs and newer markers for the prediction of fracture risk and monitoring the treatment of osteoporosis.Methods: evidence for the relationship between BTMs and subsequent fractures was gathered from prospective studies through literature review of the Medline database from years 2011 to May 2024. The impact of treatment on BTMs was also studied by examining publications in that period. Studies of the accuracy of BTMs in the assessment of bone turnover in the setting of advanced chronic kidney disease were also examined.Results: increased BTM concentrations are associated with higher fracture risk in postmenopausal women. PINP and β-CTX-I measured in blood are associated with fracture risk but their interaction with other risk factors has not been sufficiently studied limiting their incorporation into fracture risk algorithms. Treatment-induced changes in PINP and β-CTX-I account for a substantial proportion of fracture risk reduction and are useful for improving adherence; they are recommended for inclusion in studies to examine adherence in individual patients. However, total PINP (tPINP) and β-CTX-I may be elevated in CKD due to renal retention. Bone alkaline phosphatase (BALP), intact PINP (iPINP), and tartrate resistant acid phosphatase 5b (TRACP5b) show the most promise in discriminating high and low turnover bone diseases in patients with advanced CKD and for predicting fracture risk, monitoring treatment response, and assessing the risk of treatment-related complications.Conclusion: we re-affirm the use of serum/plasma tPINP and plasma β-CTX-I as reference BTMs with appropriate patient preparation and sample handling and measurement by standardized/harmonized assays in clinical studies to accumulate further data, and for monitoring treatment of osteoporosis in the setting of normal renal function in clinical practice. BALP and TRACP5b, measured by standardized assays, are recommended as reference BTMs for CKD-associated osteoporosis and should be included in observational and intervention studies to ascertain their utility for risk-evaluation, treatment initiation, and assessment of treatment response in CKD-associated osteoporosis.</p

The International Trifecta^TM and Epic^TM Valve-in-Valve Registry: insights into clinical &amp; hemodynamic outcomes

Background: little is known about the clinical and hemodynamic outcome of valve-in-valve transcatheter aortic valve replacement (ViV-TAVR) for failed Trifecta surgical aortic bioprotheses.Aims: we aimed to compare outcomes of valve-in-valve transcatheter aortic valve replacement (ViV-TAVR into failed TrifectaTM vs. ViV-TAVR into a standard aortic bioprosthetic valve with internally mounted leaflets (EpicTM, Abbott, Minneapolis, MN).Methods: data of consecutive patients who underwent ViV-TAVR into either failed TrifectaTM or EpicTM bioprostheses between October 2015 and June 2020 were retrospectively collected within the International Trifecta and Epic Valve-in-Valve Registry, and analyzed for a primary composite outcome of 30-day mortality and/or coronary obstruction (CO), defined as: (1) CO resulting in myocardial infarction and/or cardiogenic shock, or (2) CO requiring emergent coronary intervention.Results: a total of 76 patients (49 Trifecta, 27 Epic) with a median age of 80 years (interquartile range [IQR] 75.0; 82.0]) and a median Society of Thoracic Surgeons-score of 5.4 (IQR 4.0; 9.8) were identified. Coronary protection techniques were more frequently performed in Trifecta than Epic patients (29.6% vs. 0%, p = 0.01). The primary composite outcome was observed in three Trifecta versus five Epic cases (6.1% vs. 20%, p = 0.1), which included one case of CO following ViV-TAVR into Epic requiring stenting. Increased rates of patient-prosthesis mismatch (PPM) following valve-in-Epic were found (41.7% vs. 75%, p = 0.08). Survival at a median of 365 days was 86.2% and did not differ between groups (log-rank p = 0.37).Conclusions: compared to a stented prosthesis without increased risk of CO, ViV-TAVR into Trifecta prostheses can be performed with low risk of CO and acceptable short-term clinical outcomes. As the rate of post-ViV PPM is substantial for both prostheses, careful patient selection is warranted. (NCT05389631).<br/

Contract Law in China

The book bridges academic insight and practical application, making it an essential resource for lawyers, judges, arbitrators, scholars, and policymakers engaged with Chinese or comparative contract law. Written with both domestic and international audiences in mind, it situates Chinese contract law within the broader global context of commercial practice and comparative legal studies

Investigations into the flow photochemical generation of triplet aryl cations, and the development of a practicable synthesis of electroluminescent ionic 2,2’-bifluorenes

The development of an optimised experimental procedure for the synthesis of tetraimidazolium and tetrabenzimidazolium ionic 2,2’-bifluorenes is reported herein. Developed iteratively through several generations, it has improved the safety and reduced the waste associated with the ubiquitous method of preparing these and related electroluminescent compounds from the literature. This procedure has then been extended to diimidazolium species’, where an X-ray crystal structure has revealed how the triflate counterions can provide a second link between the alkylimidazolium residues and the photoluminescent core.Additionally, building upon recent work within the Harrowven group, an investigation into the flow photochemical generation of triplet aryl cations from benzyl ortho-iodophenyl ethers has produced an array of functionalised benzochromenes, including new examples and the optimisation of some that have been previously reported. Several side reactions have been examined in detail, including the alternate formation of biaryl acetamides and fluorenes. The reaction has also been extended to the synthesis of encumbered biaryls by the inclusion of ortho and ortho’ substituents on the benzyl ring

Membrane quantum well lasers and tantalum pentoxide optical waveguides

This thesis investigates two different optical technologies, membrane quantum well lasers and tantalum pentoxide rib waveguides and resonators. The former technology is explored as a potential coherent light source and amplifier for photonic integrated circuits. The latter technology is studied with the aim of exploiting the material’s high nonlinear properties to generate Kerr frequency combs for various applications such as optical telecommunications and remote sensing.Membrane quantum well lasers are semiconductor edge emitting laser devices, where stimulated emission occurs in the quantum well regions and is enhanced due to the strong waveguiding effect. The laser is optically pumped while in contact with a silicon carbide or silicon dioxide on silicon wafer as part of the heatsinking system. Oxidised silicon is of great interest due to the fact that many wafers are silicon based. Here I demonstrate the device’s lasing performance such us output power, spectral tunability, single and multiple laser cavity operation using imaging and pump beam shaping techniques. Phase locked laser arrays were particularly investigated with respect to their mutual phase relationship on a silicon dioxide substrate.Models were developed to simulate waveguiding inside the membrane quantum well lasers and therefore, the display the guided transverse electric and magnetic modes to extract information such as effective and group refractive index and free spectral range between the laser’s longitudinal modes. An attempt was also made to simulate laser arrays based on gain – guiding. Tantalum pentoxide rib waveguides and micro – ring and racetrack resonators were fabricated inside a cleanroom via photolithography and electron beam lithography for comparison. Transmission spectra were acquired from the structures to calculate optical losses, quality factors, resonant probe wavelengths in the vicinity of 1.55 μm, linewidth full – width at half – maximum, free spectral ranges and resonator finesse. Despite quality factors being of the order of 10^5, no Kerr frequency combs were observed.Models were developed to simulate waveguiding in tantalum pentoxide linear waveguides and resonators, from which effective refractive indices and effective areas were extracted after sweeping the probe wavelength. A numerical model was created and introduces the propagation mode parameters to generate Kerr frequency combs.<br/