Lifetime Studies Research Articles

Foot and ankle Osteoarthritis and Cognitive impairment in retired UK Soccer players (FOCUS): protocol for a cross-sectional comparative study with general population controls

IntroductionProfessional footballers commonly experience sports-related injury and repetitive microtrauma to the foot and ankle, placing them at risk of subsequent chronic pain and osteoarthritis (OA) of the foot and ankle....

Bright blue emissions on UV-excitation of LaBO3 (B=In, Ga, Al) perovskite structured phosphors for commercial solid-state lighting applications

Bright blue photoluminescence (PL) was obtained from Bi3+-activated LaBO3 (B = In, Ga, Al) perovskite nanophosphors. A cost-effective and low-temperature chemical route was employed for preparing Bi3+ doped LaBO3 (B=In, Ga, Al) which were then annealed at 1000 °C. The phase formation, morphological studies and luminescent properties of the as-prepared samples were performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence and optical absorption spectroscopy. Comparison of emission intensities, lifetime studies, energy band gaps and color purity of all samples (pure and Bi3+ doped) were investigated for promising applications in UV light-emitting diodes, variable frequency drive (VFD), field emission display (FED), and other photoelectric fields.

Survey on WSN Network Lifetime Through Leach Clustering Schemes

Sensor nodes deployed in wireless sensor networks (WSN) are resource constrained, battery operated and have a restricted energy resource. The significant number of wireless sensor network applications aim to extend the longevity of the network by using various strategies. Clustering algorithms were proven to be among the best efficient ways for increasing wireless sensor network reliability. In a wireless sensor network, clustering-based solutions control the network operations to manage the restricted energy in the optimal effective way to extend the network lifetime. Reviews in related subject could assist in gathering thorough and timely information about wireless sensor networks lifetime study through different clustering protocols. This research review study paper presents an extensive study of existing low energy adaptive clustering hierarchy (LEACH) homogeneous clustering procedures and analysis.

Microscale white light emitters fabricated by two-photon polymerization lithography on functional resist

Micrometric white light emitters were fabricated by applying two-photon polymerization (TPP) lithography to a chemically modified resist. Such a functional resist (FR) was doped with fluorescent molecules to turn it emitting into the whole visible region. The TPP has shown to be a versatile, low cost maskless technique capable to fabricate highly resolved structures in our FR's. The spectroscopic and chromaticity properties of the FR and fabricated microscale structures were investigated. Structures emitting high quality of white light were obtained and classified into two categories: physical and physiological white light emitters. Finally, a lifetime study was performed with the aim to apply such structures as light sources for on chip integrated photonic devices.

Endoparasitism of Golden Retrievers: Prevalence, risk factors, and associated clinicopathologic changes.

Endoparasitism is a common disease in dogs throughout their lifetime despite the widespread availability of inexpensive diagnostic tests and effective treatments. The consequences of host parasite interactions in otherwise apparently healthy dogs remains largely unknown. This cross-sectional study used complete blood count, serum biochemistry, and fecal flotation data collected from 3,018 young dogs (<3 years of age) enrolled within the Morris Animal Foundation Golden Retriever Lifetime Study (GRLS) to determine the prevalence of endoparasitism and compare bloodwork values of parasite positive and negative participants using logistic regression. Variables including age, gender, reproductive status, and geographic region at the time of evaluation were assessed to identify potential associations. To the authors' knowledge, a comprehensive assessment of clinicopathological changes associated with endoparasite infection in a large cohort has not been completed in the recent decade. The overall prevalence of endoparasitism was 6.99% (211/3018). Dogs who were parasite positive had statistically lower albumin (P = 0.004), lower RBC count (P = 0.01), higher neutrophil count (P = 0.002), and higher platelet count (P <0.001) as compared to parasite negative dogs. It was also concluded that dogs living in rural areas were more likely to have endoparasites than those living in suburban areas. Epidemiological data is crucial for the design and monitoring of prevention and control strategies. Identification of endoparasites by fecal testing is an essential tool to identify susceptible and resistant animals that can act as spreaders and reservoirs of intestinal parasites thereby enabling appropriate therapy and reducing the risk of new infection to animals and humans. Further epidemiological studies are needed to prevent, monitor, and develop new strategies to control endoparasites.

Fatigue and fracture-induced defect structures of metals investigated by positron microscopy

Abstract Defect distributions close to cracks from monotonic and fatigue fractures have been investigated for the first time by positron lifetime studies. The positron beams probe either the depth profile of defects at sub-μm resolution or the lateral distribution of defects at a few μm spatial resolution. Both in pure Cu and in the precipitation-hardened alloy Al 6013, in addition to dislocations, large clusters of up to 30 vacancies were detected close to a fatigue crack exclusively, whereas at monotonic fractures only the annihilation characteristics of dislocations were observed. If this characteristic difference holds as a general rule, then positron lifetime microscopy will provide a simple, quantitative method to distinguish a posteriori monotonic fractures from fatigue fractures without any further fractographic studies.

A computational study of carrier lifetime, doping concentration, and thickness of window layer for GaAs solar cell based on Al2O3 antireflection layer

This paper reports on the computational study to investigate the high-performance gallium arsenide (GaAs) solar cells based on the Al2O3 antireflection coating (ARC) layer by optimizing the carrier lifetime, doping concentration, energy bandgap, thickness of window and absorber layers. In this simulation, the parameters like GaAs as an absorber layer, CdS as a window layer, and fixed thickness of the Al2O3 ARC layer were selected for performing the personal computer one dimensional (PC1D) simulation. As compared to GaAs solar cell with no ARC layer, GaAs solar cell with Al2O3 ARC layer (90 nm) presented the high power conversion efficiency (PCE) of 24.60% at absorber thickness 6 μm and 30 nm for window layer. The optimized values of carrier lifetime and doping concentration for high PCE were found to be 100 μs and 1 × 1017 cm−3 for both absorber and window layers, respectively. The Voc, PCE, and fill factor (FF) values gradually increased with the increase of carrier lifetime and doping concentration of the CdS window layer. At optimized parameters, the highest value of Isc = 3.11 A, Voc = 0.884 V and PCE = 24.60% were achieved by GaAs solar cells with Al2O3 ARC layer. This study proves that optimization of CdS window layer through carrier lifetime, thickness, doping concentrations, and bandgap, etc. would make the crucial component to manufacture cost-effective, high-performance GaAs solar cells based on Al2O3 ARC layer.

Transforming incipient to real ferroelectrics in SrTiO3 upon doping luminescent Eu3+ /Tb3+ ions and the generation of white light for piezo-phototronics application

A novel effort has been given to transform the incipient ferroelectrics behavior to real in SrTiO3 and to generate white-light emission by doping luminescent Eu3+ and Tb3+ ions. Ferroelectric study showed that upon doping Eu3+ ion, SrTiO3 became pure ferroelectric in nature and upon co-doping Tb3+ ion there is a significant enhancement of the saturation polarization. Photoluminescence study showed that both the Eu3+ doped and Eu3+& Tb3+ co-doped compounds are white-light-emitting materials due to perfect combination of blue light originated from defect centers present in the host with the green and red emissions from the dopant ions. Such white-light-emitting materials with controlled piezo potential may not need external excitation energy and have potential application in many flexible optoelectronic devices. Lifetime study confirmed the existence of two components for both the dopant ions and suggested that there is an asymmetric environment created due to distortion of geometry, which is linked to ferroelectric property. Finally, all the experimental results were supported by Hybrid functional based theoretical calculation. We have observed that the bond angle variance (BAV) parameter and distortion index (DI), which are directly linked with the distortion in the matrix, are responsible for ferroelectric behavior and they follow the order with the dopant ions as Eu3+&Tb3+>Tb3+>Eu3+. This corroborates well with the experimentally observed trend of the saturation polarization.

Generating pure red and near white light in NaLaF4 microcrystal by controlling site-selective luminescence of Eu3+ and Tb3+ dopant ions

Here in this work, we aim to develop both red and near white light emitting phosphor materials using Eu3+ and Tb3+ as co-dopant ions and NaLaF4 as host matrix. It was observed that both Na and La atom possess two different types of lattice sites having different co-ordination and symmetry. We have theoretically calculated the substitution energies for Eu3+ and Tb3+ ions for all the available lattice sites and found that the preference of distribution of the dopant ions into these lattice sites is different. While Eu3+ ion prefers 9-coordinated Na1/La2 site and 6-coordinated Na2 site, Tb3+ prefers 9-coordinated La1 site. This is also reflected in the PL study of both pure Eu3+ and Eu3+-Tb3+ co-doped compounds. Substitution of Eu3+ ion at Na2 site results in short-lifetime value and highly intense red ED line as observed from time resolved spectra analysis at different delay time. On contrary, its lifetime value was found to be higher at 9-coordinated La2 site and resulting higher intense orange MD line. Defect centres, which are being created due to charge imbalance during substitution at Na site, is solely responsible for such behaviour. Increasing concentration of Eu3+ ions also resulted in higher red colour purity of the Eu3+ doped compound due to more defect induced asymmetry surrounds Eu3+ ion. For the Eu3+-Tb3+ co-doped compounds, the Tb3+→Eu3+ energy transfer dynamic is responsible for tuneable emission colour characteristics from white light to red. From lifetime study with varied concentration of Tb3+ ion, we have observed that the possibility of charge transfer from Tb3+ ion at Na-site (Tb3+Na1) to Eu3+ ion at Na2 (Eu3+Na2) is more compared to that from Tb3+La2 to Eu3+Na2.

A modeling study of lifetime and performance improvements of solid oxide fuel cell by reversed pulse operation

Chromium poisoning of the air electrode is a primary degradation mechanism for solid oxide cells (SOCs) operating under fuel cell mode. Recent experimental findings show that reversed pulse operation for SOCs operated as electrolyser cells can reverse this degradation and extend the lifetime. Here, we use a multiphysics model of an SOC to investigate the effects of reversed pulse operation for alleviating chromium poisoning of the air electrode. We study the effects of time fraction of the operation under fuel cell and electrolysis modes, cyclic operation starting after a certain duration, and fuel cell and electrolysis current densities on the cell lifetime, total power, and hydrogen production. Our modeling shows that reversed pulse operation enhances cell lifetime and total power for all different cases considered in this study. Moreover, results suggest that the cell lifetime, total power, and hydrogen production can be increased by reversed pulse operation at longer operation times under electrolysis mode, cyclic operation starting from the beginning, and lower electrolysis current densities. All in all, this paper documents and establishes a computational framework that can serve as a platform to assess and quantify the increased profitability of SOCs operating under a co-production operation through reversed pulse operation.

Identification of OLED Degradation Scenarios by Kinetic Monte Carlo Simulations of Lifetime Experiments.

We show how three-dimensions kinetic Monte Carlo simulations can be used to carry out an operational lifetime study of thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) and to deduce the sensitivity to various degradation scenarios. The approach is demonstrated for an experimentally well-characterized efficient green-emitting device. The simulation workflow includes an equilibration phase, an equilibrated pristine state phase and a degradation phase. Acceleration of the simulations by extrapolation from simulations at large current densities makes the simulation time realistically feasible. Such a procedure is also often followed in experimental studies. Degradation is assumed to be triggered by exciton-polaron quenching and exciton-exciton annihilation processes. A comparison of the simulated and experimental time-dependence of the luminance decay provides the probability that a degradation-triggering event leads to the formation of a degraded molecule. For the TADF OLED that has been studied, this parameter is only weakly dependent on the assumed scenario, provided that the degraded molecules are assumed to form trap sites, and is found to be . The approach is expected to enable systematic in silico studies of the operational lifetime and its sensitivity to the material composition, layer structure, charge carrier balance, and the use of refined device principles such as hyperfluorescence.

Bi3+ sensitized Gd2O3:Eu3+: A potential red phosphor for UV LED pumped white light emission

Bi3+ sensitized Gd2O3:Eu3+ phosphors were synthesized by hydrothermal method using polyvinylpyrrolidone as capping agent. As-prepared samples exhibit crystalline hexagonal phase Gd(OH)3. While post annealing at 900 °C, Gd(OH)3 transforms to cubic phase Gd2O3. The lattice substitution by Bi3+ in different symmetry sites, viz. C2 and S2 of Gd2O3 leads to 2 (two) prominent excitation bands related to the 1S0 → 3P1 of Bi3+. Both the excitation bands induce efficient energy transfer to the excited states of Eu3+. In both the cases, the energy transfer efficiency can reach upto ~97%. The energy transfer from the sensitizer (Bi3+) to the activator (Eu3+) occurs mainly through dipole-dipole interactions. The occurrence of energy transfer from Bi3+ to the Eu3+ is corroborated from both the steady state and decay lifetime studies. Color saturation of the red emission when excited in the wavelength range ~330–380 nm is observed ~70–85%. CIE chromaticity reveals the tunability of the color emission by changing the activator concentration.

Cost-Effectiveness of Canakinumab From a Canadian Perspective for Recurrent Cardiovascular Events

BackgroundCardiovascular (CV) disease is a condition with high levels of morbidity and mortality. Canakinumab is a novel monoclonal antibody therapy that has been shown to reduce CV events but is associated with side effects and high cost. The main objective for this analysis is to determine whether canakinumab use is cost-effective for the prevention of recurrent CV events. MethodsA decision model was developed to estimate the direct costs and outcomes among patients who have suffered a myocardial infarction and are treated with canakinumab. A lifetime study horizon was used to analyze the base-case costs and utilities from the perspective of the Canadian publicly funded healthcare system. Markov modeling was used in combination with Monte Carlo simulation to derive expected values for costs and quality-adjusted life years (QALYs), permitting the calculation of incremental cost-effectiveness ratios. ResultsCanakinumab was associated with higher average lifetime costs per patient ($457,982 vs $82,565) and higher average QALYs per patient (14.90 vs 14.20), compared with standard of care. Thus, the incremental cost per QALY gained for canakinumab treatment vs standard-of-care therapy was $535,365. The probability that canakinumab treatment is cost-effective was 0%. Results were consistent over a range of scenario analyses. ConclusionsTreatment of patients post–myocardial infarction with canakinumab is not cost-effective, compared with standard-of-care therapy at the current price. Based on currently accepted willingness-to-pay thresholds in Canada, a reduction in price of 91% is required to yield a cost per patient that would be considered appropriate.

Deep reddish-orange emitting Sr3Gd(PO4)3: Sm3+ phosphors via modified citrate-gel combustion method

The photoluminescence properties of different concentrations of Sm3+ activated Sr3Gd(PO4)3 phosphors synthesized by modified citrate gel-combustion method were investigated for white light emitting diode (w-LED) applications. The studied phosphors were characterized through powder x-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), photoluminescence excitation, emission and lifetime studies. The PXRD profiles confirmed the body centred cubic structure of undoped and Sm3+ -doped phosphors. The SEM studies showed the distribution and agglomeration of particles. The characteristic emission transitions such as 4G5/2 → 6H5/2 (∼561 nm), 4G5/2 → 6H7/2 (∼598 nm), 4G5/2 → 6H9/2 (∼645 nm) and 4G5/2 → 6H11/2 (∼705 nm) were noticed at their respective positions when excited at 403 nm wavelength. The highest luminescence intensity was found for 1.0 mol% of Sm3+ doped phosphors at 403 nm excitation showing luminescence quenching and it was ascribed to dipole-dipole interaction type of energy transfer among the excited Sm3+ ions at higher concentrations. The reddish-orange color of emitted luminescence was examined by evaluating the chromaticity coordinates. The experimental results confirm the potentiality of studied phosphors for w-LED applications.

A dynamic measure of divergence between two inactivity lifetime distributions

This paper introduces a dynamic divergence measure to assess the discrepancy between the distribution functions of two inactivity lifetime random variables. Various time-dependent results on the proposed divergence measure in connection to other well-known measures in reliability engineering and survival studies are investigated. Some aging and monotonicity properties of such a measure are also studied. Furthermore, the proposed criterion is examined in two general classes of transformation models which results in some well-known models in the lifetime studies and survival analysis.

Development challenges for carcinogenicity risk assessments of topical drugs.

The nonclinical safety package to support development and approval of drugs intended to be administered by topical application generally follows International Council for Harmonisation multidisciplinary 3 (ICH M3) and topic specific safety (ICH S) guidances. However, some aspects of topical drug development may require case-by-case determination of nonclinical safety strategies. The necessity to conduct a dermal rodent carcinogenicity study is one such example that is not considered an obligate component of a nonclinical safety data package for drug approval. While absence of systemic exposure, as stated in ICH M3, is a primary reason to forego a dermal carcinogenicity assessment, there may also be other factors for consideration in determining the need for a life-time carcinogencity study by dermal route to aid in the overall human cancer risk assessment. We therefore reviewed nonclinical carcinogencity data packages from drugs approved by the FDA or PMDA over a ~25 year time period to evaluate outcomes of oral versus topical carcinogencity studies and to understand their utility for informing the overall human risk assessment. We also discuss various other properties of topical small molecules that could impact the decisions to conduct a dermal life-time rodent carcinogenicity study. Collectively, the need to conduct 2-year dermal carcinogenicity studies in rodents should be determined case-by-case and consider scientific factors such existing systemic toxicity and carcinogenicity study data, anticipated drug exposures in skin, skin evaluation from the chronic minipig toxicity study, and genetic toxicity profile.

Photophysical and molecular docking approach on the interaction of water-soluble simple keto sugar with acridinedione dyes

Photophysical studies in association with molecular docking (MD) methods were employed in the determination of various molecular interactions existing between d-Fructose in the presence of a photoinduced electron transfer (PET) and non-PET based acridinedione (AD) dyes in water. Addition of fructose to AD dyes resulted in a decrease in the absorbance at the longest wavelength absorption maxima accompanied with the formation of an isosbestic point signifying a ground state complex formation. The ground state interaction between fructose and dye is presumably attributed to hydrogen-bonding (HB) and was authenticated by MD studies. Interestingly, the excited state characteristics of PET dye (ADR1) is found to be entirely different from that of non-PET dye (ADR2) on the introduction of fructose. A fluorescence quenching phenomenon is observed in PET dye, whereas an enhancement results in that of a non-PET dye. Fructose promotes electron transfer (ET) through space resulting in a decrease in the fluorescence intensity of ADR1 dye. On the contrary, it suppresses the PET process in ADR2 dye resulting in an increase in the quantum yield. Fluorescence lifetime studies of fructose with AD dyes results in a multi exponential lifetime with varying proportions. The presence of biexponential lifetime components justifies the existence of more than one distinguishable micro heterogenous environment in the aqueous phase containing unequal proportion of distribution of fructose and water molecules around the close vicinity of AD dyes. The local excited (LE) state of the fluorophore experiences a large variation in the excited state such that the emission intensity and fluorescence lifetime are governed by solute induced and solvent mediated HB interactions. MD studies further establish the existence of HB interaction of dye-fructose, wherein the dye acts as the HB donor and sugar as the acceptor. Docking techniques establishes clear and authentic information on the HB donor and acceptor sites in dye and sugar molecule resulting in a most stable conformer. The nature of interaction of a simple sugar molecule with water soluble fluorophores are explored in depth by fluorescence techniques in coordination with MD methods is imparted in the present study.

Modelling of Wind Turbine Operation for Enhanced Power Electronics Reliability

Enhancing power electronics (PE) converter reliability is crucial for ensuring a reliable operation of current and future operating Wind Turbines (WTs). Achieving high reliability of variable speed WT PE systems requires careful consideration of their operation, and particularly their thermal cycling. This paper presents a methodology for evaluating and reconsidering operational strategies of WTs with relation to the thermal loading and lifetime consumption of the converter. The methodology is applied to compare control strategies for the WT generator and evaluate their impact on the converter reliability by observation of the thermal cycles and by calculating the resultant lifetime consumption of those stress cycles. The thermal stress on both the Machine Side Converter (MSC) and the Grid Side Converter (GSC) is examined and compared. It is shown that the least reliable of the three evaluated control strategies is the one that tracks the power curve below rated speed most closely. This paper suggests that dynamic transients associated with the WT control largely influence the IGBT module wear-out and their modelling needs to be prioritized for lifetime studies. These dynamic transients are captured by the improved model whose value is confirmed for the comparisons in the case study of the paper.

Факторы, способствующие поддержанию эпизоотического неблагополучия по бруцеллезу в Российской Федерации

The scientific article presents generalized results of laboratory studies on brucellosis of animals in order to study the epizootic situation and identify the main causes of epizootic outbreaks in Russia for the period from 2019 to 2021. The data source is the materials of annual reports submitted by the state veterinary laboratories of the subjects of the Russian Federation on the reporting form 4-vet, other official statistical data of the veterinary and medical services of the country. In the Russian Federation, new epizootic foci of brucellosis are detected annually. Different animal populations (cattle, small cattle, pigs, reindeer, dogs) are involved in the epizootic process of brucellosis. So, for the period from 2010 to 2020, 4,283 unfavorable points for brucellosis of cattle were identified in the country, 398 for brucellosis of small cattle, which contained 95 979 and 15 880 heads of sick animals, respectively. According to the results of laboratory diagnostics of brucellosis of animals by bacteriological methods performed by state veterinary laboratories of the subjects of the Russian Federation for the period from 2019 to 2021, the culture of the causative agent of the disease was isolated in 44 cases. When conducting mass lifetime studies by serological methods, animals that respond positively to brucellosis are detected annually, from 7920 to 13 059 individuals. The main causes of epizootic outbreaks of brucellosis of animals: incomplete and untimely identification of sick individuals; violation of the deadline for slaughtering positively reacting to brucellosis and sick animals (overexposure in the farm); non-compliance by business entities with the requirements of Veterinary rules on brucellosis of animals; concealment by animal owners from the state veterinary service of the true number of livestock, which does not allow to cover all animals specific vaccination and diagnostic tests. It can be concluded that the epizootic situation of brucellosis remains quite tense on the territory of the Russian Federation. Untimely and incomplete detection of the causative agent of the disease is the cause of infection of animals and causes a long course in disadvantaged areas.

Three‐terminal perovskite/integrated back contact silicon tandem solar cells under low light intensity conditions

AbstractThe current climate and energy crisis urgently needs solar cells with efficiencies above the 29% single junction efficiency bottleneck. Silicon/perovskite tandem solar cells are a solution, which is attracting much attention. While silicon/perovskite tandem cells in 2‐terminal and 4‐terminal configurations are well documented, the three‐terminal concept is still in its infancy. It has significant advantages under low light intensities as opposed to concentrated sunlight, which is the critical factor in designing tandem solar cells for low‐cost terrestrial applications. This study presents novel studies of the sub‐cell performance of the first three‐terminal perovskite/silicon selective band offset barrier tandem solar cells fabricated in an ongoing research project. This study focuses on short circuit current and operating voltages of the sub‐cells under light intensities of one sun and below. Lifetime studies show that the perovskite bulk carrier lifetime is insensitive to illumination, while the silicon cell's lifetime decreases with decreasing light intensity. The combination of perovskite and silicon in the 3T perovskite‐silicon tandem therefore reduces the sensitivity of VOC to light intensity and maintains a relatively higher VOC down to low light intensities, whereas silicon single‐junction cells show a marked decrease. This technological advantage is proposed as a novel advantage of three‐terminal perovkite/silicon solar cells for low light intensities of one sun or less.