Increase In Lifetime Research Articles

Carrier Recombination Dynamics of Surface-Passivated Epitaxial (100)Ge, (110)Ge, and (111)Ge Layers by Atomic Layer Deposited Al2O3

Germanium (Ge) and its heterostructures with compound semiconductors offer a unique optoelectronic functionality due to its pseudo-bandgap nature, that can be transformed to a direct bandgap material by providing strain and/or mixing with tin. Moreover, two crystal surfaces, (100)Ge and (110)Ge, that are technologically important for ultralow power fin or nanosheet transistors, could offer unprecedented properties with reduced surface defects after passivating these surfaces by atomic layer deposited (ALD) dielectrics. In this work, the crystallographically oriented epitaxial Ge/AlAs heterostructures were grown and passivated with ALD Al2O3 dielectrics, and the microwave photoconductive decay (μ-PCD) technique was employed to evaluate carrier lifetimes at room temperature. The X-ray photoelectron spectroscopy analysis reveals no role of orientation effect in the quality of the ALD Al2O3 dielectric on oriented Ge layers. The carrier lifetimes measured using the μ-PCD technique were benchmarked against unpassivated Ge/AlAs heterostructures. Excitation wavelengths of 1500 and 1800 nm with an estimated injection level of ∼1013 cm–3 were selected to measure the orientation-specific carrier lifetimes. The carrier lifetime was increased from 390 ns to 565 ns for (100)Ge and from 260 ns to 440 ns for (110)Ge orientations with passivation, whereas the carrier lifetime is almost unchanged for (111)Ge after passivation. This behavior indicates a strong dependence of the measured lifetime on surface orientation and surface passivation. The observed increase (>1.5×) in lifetime with Al2O3-passivated (100)Ge and (110)Ge surfaces is due to the lower surface recombination velocity compared to unpassivated Ge/AlAs heterostructures. The enhancement of carrier lifetime from passivated Ge/AlAs heterostructures with (100)Ge and (110)Ge surface orientations offers a path for the development of nanoscale transistors due to the reduced interface state density.

Mathematical Physics of Time Dilation through Curved Trajectories with Applications

In special relativity, the time dilation formula has been obtained by particles propagation in a straight line trajectory relative to an observer in motion. Up to now, there are no available formulas for other possible trajectories of particles. However, this paper obtains formulas of time dilation for several trajectories of particle such as parabolic, elliptic, and circular and finds a relatively accurate trajectory. The obtained formulas are employed in order to analyze the time dilation of the muon particles decay. In this paper, it is found that the time dilation of the parabolic and the elliptical trajectories exceed the corresponding results utilizing the standard Lorentz-Einstein time dilation formula. Consequently, if we are able to control the trajectory of unstable particles by some external forces, then their life-times might be increased. Probably, the increase in lifetime via a curved trajectory occurs at lower relative velocity & acceleration energy if compared to the straight line trajectory. In addition, the circular trajectory leads to multiple values of time dilation at certain velocities of an observer in motion, which may give an interpretation of fluctuations of time dilation in quantum mechanics. The result arises from the present relatively accurate formula of time dilation that is very close to the experimental data of muon decay (CERN experiment) when it is compared to the result obtained by the Lorentz-Einstein formula. Finally, it may be concluded that the time dilation not only depends on relative velocity and acceleration energy of particles but also on curved trajectories. The present work may attract other researchers to study different trajectories.

Bichromophoric Photosensitizers: How and Where to Attach Pyrene Moieties to Phenanthroline to Generate Copper(I) Complexes

Pyrene is a polycyclic aromatic hydrocarbon and organic dye that can form superior bichromophoric systems when combined with a transition metal-based chromophore. However, little is known about the effect of the type of attachment (i.e., 1- vs 2-pyrenyl) and the individual position of the pyrenyl substituents at the ligand. Therefore, a systematic series of three novel diimine ligands and their respective heteroleptic diimine-diphosphine copper(I) complexes has been designed and extensively studied. Special attention was given to two different substitution strategies: (i) attaching pyrene via its 1-position, which occurs most frequently in the literature, or via its 2-position and (ii) targeting two contrasting substitution patterns at the 1,10-phenanthroline ligand, i.e., the 5,6- and the 4,7-position. In the applied spectroscopic, electrochemical, and theoretical methods (UV/vis, emission, time-resolved luminescence and transient absorption, cyclic voltammetry, density functional theory), it has been shown that the precise choice of the derivatization sites is crucial. Substituting the pyridine rings of phenanthroline in the 4,7-position with the 1-pyrenyl moiety has the strongest impact on the bichromophore. This approach results in the most anodically shifted reduction potential and a drastic increase in the excited state lifetime by more than two orders of magnitude. In addition, it enables the highest singlet oxygen quantum yield of 96% and the most beneficial activity in the photocatalytic oxidation of 1,5-dihydroxy-naphthalene.

1H- and 2H-1,2,3-triazoles hybrids: Comparative study of photophysical properties

The photophysical properties of three types of hybrid molecules, containing two 1,2,3-triazole isomers with different spatial arrangements and set of surrounding substituents, were investigated. The effect of the heterocyclic scaffold construction and the nature and position of the substituents were revealed by spectral and computational investigations. UV–Vis absorption spectra showed maxima with high molar extinction coefficients. Moderate blue emission (QYs up to 42.2%) and average fluorescence life-time of 1.05–4.53 ns were determined. Positive solvatochromism and intramolecular charge transfer were detected and confirmed by the quantum mechanical calculations. A peculiar effect of a hydrogen bond formation was registered in MeOH, EtOH, i-PrOH, ethylene glycol (EG) solutions and water mixtures. The compounds exhibited an Aggregation Induced Emission Enhancement (AIEE) effect in DMSO-H2O mixtures with a 1.3–3.1 fold increase of QYs and a 1.1–2.8 fold increase of fluorescence life-time. Molecular geometries and electronic characteristics were studied at (Time Dependent) Density Functional Theory ((TD-)DFT) level. The biological behavior of 2H-bis[1,2,3]triazolo)[5,1-a:4′,5′-c]isoquinolines was studied by means of confocal microscopy experiments, which showed that these compounds successfully penetrate the cell membranes, accompanied by bright emission in the cytoplasmic region of the confocal micrographs.

LCA approach for environmental impact assessment within the maritime industry: Re-design case study of yacht’s superstructure

Sustainable development, one of the main challenges of our time, is a policy focused on the perfect balance between three fundamental pillars: environmental, economic and social sustainability. As regards the environmental protection, the Life Cycle Assessment (LCA) methodology allows to evaluate the sustainability profile of the overall Life-Cycle (LC) of products, processes and services, based on an inventory (in terms of materials/energy consumption and emissions/waste production) referred to all LC stages. The paper describes an application of LCA in the maritime transportation field, after a careful analysis of the state of the art. In particular, the case study consists in the environmental comparison of two alternative design solutions for the superstructure of a Azimut-Benetti yacht, designed by Corporate R&D department and manufactured in one of Benetti botyards. The competing construction options are a Glass Fiber reinforced Vinylester-isophthalic Resin (GFVR) and a Carbon Fiber reinforced Epoxy Resin (CFER) component, and they are assessed in terms of Global Warming Potential through the CML2001 Life Cyle Impact Assessment (LCIA) method. The study takes into account the entire LC of the superstructure component, divided into production (including raw materials, manufacturing and transportations), use (including both fuel consumption and exhaust air emissions) and End-of-Life (EoL). The Life Cycle Inventory (LCI) is mainly based on primary data (materials and energy consumption for manufacturing) directly provided by the construction company; missing data are retrieved from secondary sources (literature and LCI database provided by the GaBi6 environmental software). Results show that, despite the higher impact in production stage, the innovative solution allows achieving a significant quota of GWP over the entire LC (more than 16%), which is mainly associated with decreased amount of fuel needed and lowered CO2 exhaust emissions during operation. The sensitivity analysis reveals that the environmental advantage provided by the CFER design becomes bigger as both component life-time and yacht consumption increase.

Improved Structural Order and Exciton Delocalization in High-Member Quasi-Two-Dimensional Tin Halide Perovskite Revealed by Electroabsorption Spectroscopy

Engineering of quasi-two-dimensional (quasi-2D) tin halide perovskite structures is a promising pathway to achieve high-performance lead-free perovskite solar cells, with recently developed devices demonstrating over 14% efficiency. Despite the significant efficiency improvement over the bulk three-dimensional (3D) tin perovskite solar cells, the precise relationship between structural engineering and electron-hole (exciton) properties is not fully understood. Here, we study exciton properties in high-member quasi-2D tin perovskite (which is dominated by large n phases) and bulk 3D tin perovskite using electroabsorption (EA) spectroscopy. By numerically extracting the changes in polarizability and dipole moment between the excited and ground states, we show that more ordered and delocalized excitons are formed in the high-member quasi-2D film. This result indicates that the high-member quasi-2D tin perovskite film consists of more ordered crystal orientations and reduced defect density, which is in agreement with the over 5-fold increase in exciton lifetime and much improved solar cell efficiency in devices. Our results provide insights on the structure-property relationship of high-performance quasi-2D tin perovskite optoelectronic devices.

Phosphorescent O2-Probes Based on Ir(III) Complexes for Bioimaging Applications

The design, synthesis, and investigation of new molecular oxygen probes for bioimaging, based on phosphorescent transition metal complexes are among the topical problems of modern chemistry and advanced bioimaging. Three new iridium [Ir(N^C)2(N^N)]+ complexes with cyclometallating 4-(pyridin-2-yl)-benzoic acid derivatives and different di-imine chelate ligands have been synthesized and characterized by mass spectrometry and NMR spectroscopy. The periphery of these complexes is decorated with three relatively small “double-tail” oligo(ethylene glycol) fragments. All these complexes exhibit phosphorescence; their photophysical properties have been thoroughly studied, and quantum chemical calculations of their photophysical properties were also performed. It turned out that the changes in the nature of the di-imine ligand greatly affected the character of the electronic transitions responsible for their emission. Two complexes in this series show the desired photophysical characteristics; they demonstrate appreciable quantum yield (14–15% in degassed aqueous solutions) and a strong response to the changes in oxygen concentration, ca. three-fold increase in emission intensity, and an excited state lifetime upon deaeration of the aqueous solution. The study of their photophysical properties in model biological systems (buffer solutions containing fetal bovine serum—FBS) and cytotoxicity assays (MTT) showed that these complexes satisfy the requirements for application in bioimaging experiments. It was found that these molecular probes are internalized into cultured cancer cells and localized mainly in mitochondria and lysosomes. Phosphorescent lifetime imaging (PLIM) experiments showed that under hypoxic conditions in cells, a 1.5-fold increase in the excitation state lifetime was observed compared to aerated cells, suggesting the applicability of these complexes for the analysis of hypoxia in biological objects.

Water Drop Evaporation on Slippery Liquid-Infused Porous Surfaces (SLIPS): Effect of Lubricant Thickness, Viscosity, Ridge Height, and Pattern Geometry.

Sessile drop evaporation and condensation on slippery liquid-infused porous surfaces (SLIPS) is crucial for many applications. However, its modeling is complex since the infused lubricant forms a wetting ridge around the drop close to the contact line, which partially blocks the free surface area and decreases the drop evaporation rate. Although a good model was available after 2015, the effects of initial lubricant heights (hoil)i above the pattern, and the corresponding initial ridge heights (hr)i, lubricant viscosity, and solid pattern type were not well studied. This work fills this gap where water drop evaporations from SLIPS, which are obtained by infusing silicone oils (20 and 350 cSt) onto hydrophobized Si wafer micropatterns having both cylindrical and square prism pillars, are investigated under constant relative humidity and temperature conditions. With the increase of (hoil)i, the corresponding (hr)i increased almost linearly on lower parts of the drops for all SLIPS samples, resulting in slower drop evaporation rates. A novel diffusion-limited evaporation equation from SLIPS is derived depending on the available free liquid-air interfacial area, ALV, which represents the unblocked part of the total drop surface. The calculation of the diffusion constant, D, of water vapor in air from (dALV/dt) values obtained by drop evaporation was successful up to a threshold value of (hoil)i = 8 μm within ±7%, and large deviations (13-27%) were obtained when (hoil)i > 8 μm, possibly due to the formation of thin silicone oil cloaking layers on drop surfaces, which partially blocked evaporation. The increase of infused silicone oil viscosity caused only a slight increase (12-17%) in drop lifetimes. The effects of the geometry and size of the pillars on the drop evaporation rates were minimal. These findings may help optimize the lubricant oil layer thickness and viscosity used for SLIPS to achieve low operational costs in the future.

PREDICTION OF EFFICACY OF DEACIDIFICATION PROCESS

The aim of this work is to propose the first model hypothesis and function for predicting the efficacy of deacidification. We have used the dDEA as the first basic factor influencing the efficacy. The resulting relationship is based on the best achieved reliable η data and related dDEA data, from mass deacidification technologies used for the lifetime and usability increase of millions of books, historical documents worldwide. The resulting η predicting function is as follows η = 0.732984+0.125612*dDEA^(-0.214237). This first 1D function can serve as an impulse for continuing improvement of the prediction, and 2D, 3D and multidimensional models. It can be used for comparisons and connecting η with η-characteristic mechanical, physical, cellulose solution properties; the prediction can serve for continuing improvement of efficacy of the conservation technology in increasing the paper carriers of information, documents longevity and usability.

Effect of surface modification on the photoluminescent properties of γ-Ga2O3 nanocrystals

Ga2O3 nanocrystals with compelling optical properties attract broad attention from the scientific and industrial community. However, the influence of surface modification on the photoluminescent properties of Ga2O3 NCs remains unexplored. Here, we report comparative investigations of the photoluminescent properties of oleylamine-capped and ligand-free γ-Ga2O3 nanocrystals. The removal of oleylamine ligand on the Ga2O3 nanocrystal surface via a post-synthesis reaction is accompanied by the accumulation of positive surface charges and a reduction of oxygen vacancies. The change of nanocrystal surface leads to an appreciable red shift of emission spectrum along with a substantial increase in photoluminescence lifetime. Modeling the photoluminescence decay dynamics of Ga2O3 nanocrystals indicate the change of photoluminescent property is correlated to the decrease of the number density of donors and donor Bohr radius resulting from the change of nanocrystal surface.

Electrical Control of Exciton Diffusion via Tuning Exciton States

AbstractStacking of monolayer 2D transition metal dichalcogenides (TMDs) into van der Waals heterostructures can enable the formation of interlayer excitons (IXs) with long lifetimes and permanent out‐of‐plane electric dipoles, allowing them to propagate over long distances. While early studies on TMD heterobilayrs show efficient electrical control of excitonic transport of IXs by creating different energy potentials, the electrically controllable exciton states and associated spatial migration remain elusive. Here, an electrical control of exciton diffusion through the change of exciton states between charged IXs (CIXs) and charged intralayer excitons is reported. The repulsive dipolar interaction of IXs accounts for the growing exciton cloud size and increasing diffusion length in the power‐dependent PL study. More importantly, the electrically tunable spatial exciton distribution is demonstrated by switching the exciton states, which shows a 1.5‐fold change in diffusion length and an order of magnitude increase in lifetime from charged intralayer excitons to CIXs. The electrical control of exciton states and the relevant diffusion dynamics provide another knob to study the interplay between propagation and many‐body interactions for the development of excitonic devices.

Coupled mass and heat transfer modelling in building envelopes to consistently assess human exposure and energy performance in indoor environments

We develop a numerical model coupling heat and chemical transfers in the building envelope to predict human exposure to pollutants and heating load as affected by changes in temperature and building design. We characterize the effect of temperature variation by season and location on chemical emission dynamics from building materials and the resulting human exposure. Peak concentrations of organics are sensitive to temperatures, and increasing indoor temperature by 10°C doubles the maximum indoor air concentration reached by both VOCs and SVOCs contained in a vinyl flooring. SVOCs mean concentration over the flooring lifetime increases by a factor of 2, and, as a result, the fraction of chemical taken in by the occupants increases by 50%. Occupants’ exposure to SVOCs emission in the city of Lille is likely to increase by 20% in 2050 because of temperature increase induced by climate change.

Tip-Induced Nanopatterning of Ultrathin Polymer Brushes.

Patterned, ultra-thin surface layers can serve as templates for positioning nanoparticlesor targeted self-assembly of molecular structures, for example, block-copolymers. This work investigates the high-resolution, atomic force microscopebased patterning of 2nm thick vinyl-terminated polystyrene brush layers and evaluates the line broadening due to tip degradation. This work compares the patterning properties with those of a silane-based fluorinated self-assembled monolayer (SAM), using molecular heteropatterns generated by modified polymer blend lithography (brush/SAM-PBL). Stable line widths of 20nm (FWHM) over lengths of over 20000µm indicate greatly reduced tip wear, compared to expectations on uncoated SiOx surfaces. The polymerbrush acts as a molecularly thin lubricating layer, thus enabling a 5000 fold increase in tip lifetime, and the brush is bonded weakly enough that it can be removed with surgical accuracy. On traditionally used SAMs, either the tip wear is very high or the molecules are not completely removed. Polymer Phase Amplified Brush Editing is presented, which uses directed self-assembly to amplify the aspect ratio of the molecular structures by a factor of 4. The structures thus amplified allow transfer into silicon/metal heterostructures, fabricating 30nm deep, all-silicon diffraction gratings that could withstand focused high-power 405nm laser irradiation.

An improved AODV routing algorithm based on energy consumption for Ad Hoc networks

The Ad Hoc networks solves the problem of quickly establishing a temporary Ad Hoc network without the need for fixed facilities. However, problems such as network performance degradation, delay increase, and link interruption are endless. Aiming at the problem of shortening the survival time of Ad Hoc networks nodes, this paper proposes an improved AODV routing algorithm EC-MAODV (Energy Consumption-Modification AODV) based on energy consumption. EC-MAODV takes energy as the starting point, determines the time extension based on the residual energy of the current node, balance the power consumption of each node, and extends the networks lifetime. The effectiveness of EC-MAODV routing algorithm is proved by network simulator NS-3. The simulation results show that compared with the AODV routing protocol, the algorithm in this paper has more than 7% improvement and 19% increase in average delay and node lifetime. It can effectively prolong the life of the network, reduce the number of dead nodes, effectively solve the energy consumption problem of the wireless Ad Hoc network, and improve the overall performance of the network.

Bifunctional Single-Molecular Fluorescent Probe: Visual Detection of Mitochondrial SO2 and Membrane Potential.

Mitochondrial membrane potential (MMP) and sulfur dioxide (SO2) significantly affect the mitochondrial state. In this work, TC-2 and TC-8 were constructed through side-chain engineering, in which TC-2 bearing the poorer hydrophobicity could localize on mitochondria better. Interestingly, short-wave emission was captured due to the sensitive response of TC-2 to SO2 (LOD = 13.8 nM). Meanwhile, the probe could bind with DNA, presenting enhanced long-wave emission. Encouragingly, TC-2 could migrate from mitochondria to the nucleus when MMP was decreased, accompanied by the increase of fluorescence lifetime (9-fold). Hence, TC-2 could be used for dual-channel monitoring of mitochondrial SO2 and MMP, which showed a completely different pathway from the commercial MMP detectors JC-1/JC-10. The cellular experiments showed that MMP was gradually decreased due to reactive oxygen species-triggered oxidative stress, and the SO2 level was up-regulated simultaneously. Overall, this work proposed a new method to investigate and diagnose the mitochondrial-related diseases.

Rational Molecular Designing of Aggregation-Enhanced Emission (AEE) Active Red-Emitting Iridium(III) Complexes: Effect of Lipophilicity and Nanoparticle Encapsulation on Photodynamic Therapy Efficacy.

Two "aggregation-enhanced emission" (AEE) active cyclometalated phosphorescent iridium(III) complexes, SM2 and SM4, were synthesized to evaluate the influence of lipophilicity on photodynamic therapy efficacy. Compared to SM2, SM4 had a higher logP due to the presence of naphthyl groups. As observed by confocal microscopy, this increased lipophilicity of SM4 significantly enhanced its cellular uptake in breast cancer cells. Both the molecules were found to be noncytotoxic under nonirradiating conditions. However, with light irradiation, SM4 exhibited significant cytotoxicity at a 500 nM dose, whereas SM2 remained noncytotoxic, signifying the influence of lipophilicity on cellular internalization and cytotoxicity. Mechanistically, light-irradiated SM4-treated cancer cells exhibited a significant increase in the intracellular reactive oxygen species (ROS) level. Neutralizing ROS with N-acetylcysteine (NAC) pretreatment partly abolished the cytotoxic ability, indicating ROS as one of the major effectors of cell cytotoxicity. Two nanoparticle (NP) formulations of SM4 were developed to improve the intracellular delivery: a PLGA-based NP and a Soluplus-based micelle. Interestingly, PLGA and Soluplus NP formulations exhibited a 10- and 22-fold increased emission intensity, respectively, compared to SM4. There was also an increase in the excited-state lifetime. Additionally, the Soluplus-based micelles encapsulating SM4 exhibited enhanced cellular uptake and increased cytotoxicity compared to the PLGA NPs encapsulating SM4. Altogether, the current study indicates the importance of rational molecular designing and the significance of a proper delivery vector for improving photodynamic therapy efficacy.

Optimization of Energy-Efficient Algorithms for Real-Time Data Administering in Wireless Sensor Networks for Precision Agriculture

Precision agriculture relies heavily on wireless sensor networks (WSNs) to monitor environmental conditions and manage resources efficiently. However, traditional WSN algorithms face significant challenges in energy management, resulting in frequent battery replacements, high maintenance costs, and reduced network reliability. Additionally, issues with high data latency and short network lifetimes hinder real-time decision-making and continuous monitoring. This study aims to address these challenges by developing energy-efficient algorithms that enhance the performance and longevity of WSNs in precision agriculture. The objectives include creating adaptive sampling, dynamic power management, and sleep scheduling algorithms to optimize energy consumption; improving data transmission efficiency and reducing latency through advanced data aggregation techniques; and extending network lifetime with balanced energy load distribution and efficient power usage strategies. The study introduces innovative algorithms that significantly reduce energy consumption and extend network lifetime, contributing to the field with adaptive and dynamic methodologies. Extensive simulations demonstrate that the proposed algorithms achieve a 30% reduction in energy consumption, a 20% decrease in data latency, and a 40% increase in network lifetime compared to traditional methods. Additionally, the packet delivery ratio improved by 10%, and computational overhead was reduced by 30%, highlighting the efficiency and reliability of the proposed solutions. These results are consistent with recent advancements in WSN optimization techniques, such as those utilizing cognitive radio and deep learning, validating the potential of the proposed algorithms for real-world application.

Tunable Hole‐Selective Transport by Solution‐Processed MoO3−x Via Doping for p‐Type Crystalline Silicon Solar Cells

Molybdenum oxide (MoO3−x, x < 3) has been successfully used as an efficient hole‐selective contact material for crystalline silicon heterojunction solar cells. The carrier transport capability strongly depends on its work function, that is, oxygen vacancies; however, there are lack of effective methods to modulate the multiple oxidation states. Herein, the oxidation states of solution‐processed MoO3−x by doping Nb5+ to improve its hole‐selective contact performance with silicon are tuned. With the optimum doping concentration of 5%, both the reduced Mo5+ and oxygen vacancies increase, resulting in a decrease in the contact resistivity between the MoO3−x film and p‐type silicon from 161.1 to 62.9 mΩ·cm2 and an increase of the effective carrier lifetime from 165.4 to 391.0 μs simultaneously. Similarly, the doping of Ta5+ or V5+ in MoO3−x improves the passivated contact performance with silicon, while the former increases the concentration of oxygen vacancies and the latter reduces it. The solar cell with the structure of Ag/MoO3−x:Nb/p‐Si exhibits a conversion efficiency of 18.37%, which is the highest so far reported for the solution‐processed MoO3−x/silicon heterojunction. This work demonstrates a feasible strategy of tuning hole selectivity in MoO3−x by doping for high‐efficiency solar cells and other optoelectronic device applications.

Improving Hands-Free Speech Rehabilitation in Laryngectomized Patients with a Moldable Adhesive.

This study aims to assess the product performance of a new moldable peristomal adhesive with corresponding heating pad designed to facilitate and improve automatic speaking valve (ASV) fixation for hands-free speech in laryngectomized patients. Twenty laryngectomized patients, all regular adhesive users with prior ASV experience, were included. Study-specific questionnaires were used for data collection at baseline and after two weeks of moldable adhesive use. The primary outcome parameters were adhesive lifetime during hands-free speech, use and duration of hands-free speech, and patient preference. Additional outcome parameters were satisfaction, comfort, fit, and usability. The moldable adhesive enabled ASV fixation adequate for hands-free speech in the majority of participants. Overall, the moldable adhesive significantly increased adhesive lifetime and duration of hands-free speech compared to participants' baseline adhesives (p< 0.05), regardless of stoma depth, skin irritation, or regular use of hands-free speech at baseline. The participants who preferred the moldable adhesive (55% of participants) experienced a significant increase in the adhesive lifetime (median of 24 h, range 8-144 h) and improved comfort, fit, and ease of speech. The moldable adhesive's lifetime and functional aspects, including the ease of use and custom fit, are encouraging outcomes and enable more laryngectomized patients to use hands-free speech more regularly. 4 Laryngoscope, 133:2965-2970, 2023.

Optimal relaying nodes selection for IEEE 802.15.6-based two-hop star topology WBAN

Wireless body area networks (WBANs) are a promising communication technology that supports various types of medical and non-medical applications with heterogeneous requirements. Generally, IEEE 802.15.6-based WBAN use one-hop star topology to establish direct communication between the hub and body sensors. The standard also supports two-hop star topology to establish communication where direct transmission between the hub and sensor nodes is not possible due to poor link quality caused by body shadowing. Data transmission reliability and network lifetime are key factors in WBANs. Therefore, we propose an optimal relaying nodes selection mechanism as an alternative to the two-hop star topology extension of IEEE 802.15.6 to enhance the packet delivery ratio, network lifetime, and throughput. In this work, while choosing a relaying node for a disconnected node, we consider the fitness value of all the relaying capable nodes and select the fittest node as relaying node. We calculate the fitness value of all the relaying capable nodes based on their link quality, residual energy, and current traffic load using the multi-criteria decision making method “Technique for Order Preference by Similarity to Ideal Solution (TOPSIS)”, which was originally developed by Ching-Lai Hwang and Yoon in 1981. We use the Mamdani fuzzy inference system (FIS) to calculate the link quality index of relaying capable nodes based on various link quality parameters such as Received Signal Strength Indicator (RSSI), Signal-to-Noise Ratio (SNR), and Packet Error Rate (PER). Moreover, we also designed a schedule slot allocation mechanism for all the sensor nodes based on their packet generation rate (PGR). The proposed scheme significantly improved packet delivery ratio, throughput, and network lifetime compared to the IEEE 802.15.6 standard’s two-hop extension of star topology and other relay selection mechanisms. The simulation result of the proposed mechanism shows that the packet delivery ratio and network lifetime increase by (5–30)% and 50% respectively, compared to the IEEE 802.15.6 two-hop star topology.