Lifetime Of Components Research Articles

Heterochiral modifications enhance robustness and function of DNA in living human cells.

Oligonucleotide therapeutics are becoming increasingly important as more are approved by the FDA, both for treatment and vaccination. Similarly, dynamic DNA nanotechnology is a promising technique that can be used to sense exogenous input molecules or endogenous biomarkers and integrate the results of multiple sensing reactions in situ via a programmed cascade of reactions. The combination of these two technologies could be highly impactful in biomedicine by enabling smart oligonucleotide therapeutics that can autonomously sense and respond to a disease state. A particular challenge, however, is the limited lifetime of standard nucleic acid components in living cells and organisms due to degradation by endogenous nucleases. In this work, we address this challenge by incorporating mirror-image, ʟ-DNA nucleotides to produce heterochiral "gapmers". We use dynamic DNA nanotechnology to show that these modifications keep the oligonucleotide intact in living human cells for longer than an unmodified strand. To this end, we used a sequential transfection protocol for delivering multiple nucleic acids into living human cells while providing enhanced confidence that subsequent interactions are actually occurring within the cells. Taken together, this work advances the state of the art of ʟ-nucleic acid protection of oligonucleotides and DNA circuitry for applications in vivo.

Health Physics Aspects Associated with Magnetic Confinement Fusion Power Facilities

Bevelacqua Resources, 7531 Flint Crossing Circle SE, Owens Cross Roads, AL 35763 USA bevelresou@aol.com Health physics aspects associated with magnetic confinement fusion are addressed. These aspects are investigated within the context of the operation of the International Thermonuclear Experimental Reactor currently called ITER. ITER has health physics elements in common with existing fission facilities as well as unique fusion related features. Fusion facility neutron radiation is similar to that encountered in a low energy accelerator. The tritium hazard has radiation protection issues in common with the Canadian Deuterium reactor. Completion of the final ITER design, its performance characteristics, component lifetimes, and maintenance requirements will determine the actual health physics hazards. Numerous open issues are required to complete the design of ITER and resolution of these issues will affect the design as well as the health physics implications for occupationally exposed workers. Key Words: Fusion Power Facility, ITER, Magnetic Confinement, Radiological Characteristics

Solid breeder material crystal structure evolution due to Li burn up–Loss of crystal stability

Solid breeder materials for fusion power plants are subjected to extreme conditions of radiation damage, high temperature and designed component burn-up. The loss of lattice stability of Li2TiO3 due to Li burn-up was investigated using first principles-based approaches to aid evaluation of upper limit of component lifetime. The lattice stability is analyzed using calculated phonon dispersion in the Li2TiO3 supercell, while Li burn-up is modeled by the introduction of Li-vacancies. It has been determined that the studied ceramic can be structurally stable up to ∼40% of Li atoms burn-up. At 50% burn-up, the negative frequency branch in the phonon dispersion spectrum appears indicating the loss of lattice dynamical stability. Moreover, the structure obtained by introduction of unstable frozen phonons with minima energy amplitude also results in a phonon dispersion with negative branches in the structure obtained. Therefore, the system completely loses stability when approximately half of Li atoms are consumed.

Process Optimization in Laser Welding of IN792 DS Superalloy

Ni-base superalloys are employed to produce parts of aeronautic engines, space vehicles and power plants. During the production process or lifetime of components, cracks may occur which affect their performance. Reliable repairs can be carried out through high-energy density welding techniques. This work investigated laser welding of the directionally solidified IN792 DS superalloy. The characteristics of the original material and their evolution in the base metal, heat-affected zone and melt zone after laser welding in different conditions and post-welding heat treatment were investigated through micro-hardness tests, light and scanning electron microscopy observations. The study allowed to optimize the process parameters and post-welding heat treatment, obtaining joints without macro-defects, such as cracks and pores, and with properties and microstructures of the melt zone like those of base metal.

Modelling of NBI shine-through in ITER non-nuclear phase to limit heat fluxes on first wall

The occurrence of localized high heat fluxes on the ITER first wall can limit the lifetime of plasma-facing components. This can be the case of excessive shine-through losses due to high-energy Neutral Beam Injection (NBI) in low density plasmas, as in the first operation phases of ITER. The use of ITER NBI will be therefore limited to densities that guarantee acceptable power fluxes on the first wall. In this work, we review the NBI shine-through issue in the ITER pre-fusion phases by numerical simulations, extending previous modelling assumptions and exploiting the IMAS modelling framework. The dependencies of shine-through on beam injection energy and plasma density profiles are discussed and a heuristic formula for shine-through fraction is proposed, fitting a large database of ad-hoc simulations. In particular the effect of NBI vertical tilt is properly taken into account by considering the effect of different plasma density profile shapes. Both on- and off-axis ITER H neutral beam injection are considered in the study. We show that increasing the density peaking, ITER NBI shine-through losses decrease, with magnitude depending on the beam vertical tilt. Two ionization codes, NEMO and BBNBI, are compared exploiting the standardized data input of the IMAS suite.

Determining the optimal design for complex systems using a reliability signature

In reliability analysis, the structure-function is a commonly used mathematical representation of the studied system. A signature vector is used for systems with independently and identically distributed (i.i.d.) component lifetimes. Each element in the signature represents the probability that the failure of the corresponding component will fail the entire system. This paper aims to provide a comprehensive understanding of assessing the performance of two complex systems for optimal communication design. The study compares two systems with the same components using signatures, expected cost rate, survival signature, and sensitivity to determine which system is preferred. It also provides several sufficient conditions for comparing the lifetimes of two systems based on the usual stochastic order. The results are applied to two communication systems that have the same components. The mathematical properties presented in the study have been proven to enable efficient weighting of the optimal design.

On conditional spacings and their properties under coherent system setting

This paper introduces the concepts of conditional spacings and normalized conditional spacings when an ( n − k + 1 ) -out-of-n system or a general coherent system having independent and identically distributed (IID) components just fails at time t. First, we obtain the marginal reliability and joint reliability of conditional spacings, and then conduct some comparisons of conditional spacings. We also investigate the dependent and ISO ∗ properties of the conditional spacings. Finally, the case when the lifetimes of components are IID exponential is discussed in detail.

Quantification and assessment of the error associated with engineering stress-strain analysis in stress accelerated creep tests in 316H stainless steel

ABSTRACT Historically, reduction of area has been neglected during uniaxial creep tests, and engineering rather than true stress-strain and strain rate have been considered. In high load accelerated tests, there is an increasing error associated with the engineering stress and strain, hence this assumption is no longer valid. In this work, uniaxial creep tests on Type 316H austenitic stainless steel at 480–550 °C have been analysed for both engineering and true stress–strain and strain rate. Significantly higher stresses and lower minimum strain rates were determined from true stress-strain rate relationships for as-received 316H. These differences diminish as the material is strain hardened, limiting plastic loading strains and reducing creep ductility. The true stress-strain rate analysis method is shown to be more accurate, however, the engineering stress-strain analysis predicts higher creep strain rates for a given stress and is the more conservative measure for component lifetime assessments.

Seed-mediated growth synthesis and tunable narrow-band luminescence of quaternary Ag-In-Ga-S alloyed nanocrystals.

Silver-based I-III-VI-type semiconductor nanocrystals have received extensive attention due to their narrow-band luminescence properties. Herein, we demonstrated a seed-mediated growth of quaternary Ag-In-Ga-S (AIGS) nanocrystals (NCs) with narrow-band luminescence. By conducting partial cation exchange with In3+ and Ga3+ based on Ag2S NCs and controlling the Ag/In feeding ratios (0.25 to 2) of Ag-In-S seeds as well as the inventory of 1-dodecanethiol, we achieved optimized luminescence performance in the synthesized AIGS NCs, characterized by a narrow full width at half maximum of less than 40 nm. Meanwhile, narrow-band luminescent AIGS NCs exhibit a tetragonal AgGaS2 crystal structure and a gradient alloy structure, rather than a core-shell structure. Most importantly, the kinetics decay curves of time-resolved photoluminescence and the ground state bleaching in transient absorption generally agree with each other regarding the lifetime of the second decay component, which indicates that the narrow-band luminescence is due to the slow radiative recombination between trapped electrons and trapped holes located at the edge of the conduction band and the deep silver-related trap states (e.g., silver vacancy), respectively. This study provides new insights into the correlation between the narrow-band luminescence properties and the structural characteristics of AIGS NCs.

Multiaxial fatigue on cableway installations components: use of the Dang Van criterion based on detail categories of EN 1993-1-9 standard.

In order to predict fatigue lifetime of cableway installations components, EN 1993-1-9 standard (Eurocode 3) is commonly used. However, EN 1993-1-9 is based on a major hypothesis : stress state has to be uniaxial. But for some components, this uniaxial hypothesis is not verified (for example : fixed grip of chairlift submitted to horizontal tightening stress and vertical load stress, or chairlift structure stressed by gravity and lateral shake when passing a tower). It then appears important to use a fatigue criterion taking into account multiaxial stress state. Our research work proposes to apply for fatigue study the Dang Van criterion, which takes into account multiaxial stress state. Results are then compared to Eurocode SN curves, representing a huge experimental database on unixaxial fatigue, that we propose to use in multiaxial fatigue thanks to an appropriate recalibration. The scientific originality of this work lies in the justification of that Dang Van criterion's recalibration. Therefore, a theorical study ensures that our use of Dang Van's multiaxial criterion is still consistant with the Eurocode SN curve even if these SN curves are experimentally performed under uniaxial stress state. Finally, that hitherto unpublished use of the Dang Van criterion makes it possible to consider the entire database of detail categories defined in NF EN 1993-1-9, by generalising their use for components under multiaxial fatigue.

Rényi entropy of past lifetime from lower $ k $-record values

<p>This paper explored the concept of past Rényi entropy within the context of $ k $-record values. We began by introducing a representation of the past Rényi entropy for the $ n $-th lower $ k $-record values, sampled from any continuous distribution function $ F, $ concerning the past Rényi entropy of the $ n $-th lower $ k $-record values sampled from a uniform distribution. Then, we delved into the examination of the monotonicity properties of the past Rényi entropy of $ k $-record values. Specifically, we focused on the aging properties of the component lifetimes and investigated how they impacted the monotonicity of the past Rényi entropy. Additionally, we derived an expression for the $ n $-th lower $ k $-records in terms of the past Rényi entropy, specifically when the first lower $ k $-record was less than a specified threshold level, and then investigated several properties of the given formula.</p>

Some new results involving residual Renyi's information measure for $ k $-record values

<abstract><p>This article dealt with further properties of the Renyi entropy and the residual Renyi entropy of $ k $-record values. First, we discussed the Renyi entropy order and its connection with the usual stochastic and dispersive orders. We then addressed the monotonicity properties of the residual Renyi entropy of $ k $-records, focusing on the aging properties of the component lifetimes. We also expressed the residual $ n $th upper $ k $-records in terms of Renyi entropy when the first dataset exceeded a certain threshold, and then studied various properties of the given formula. Finally, we conducted a parametric estimation of the Renyi entropy of the $ n $th upper $ k $-records. The estimation was performed using both real COVID-19 data and simulated data.</p></abstract>

Cumulative entropy properties of consecutive systems

<p>We investigated certain properties of cumulative entropy related to the lifetime of consecutive $ k $-out-of-$ n $:F systems. First, we presented a technique to compute the cumulative entropy of the lifetimes of these systems and studied their preservation properties using the established stochastic orders. Furthermore, we derived valuable bounds applicable in cases where the distribution function of component lifetimes is complex or when systems consist of numerous components. To facilitate practical applications, we introduced two nonparametric estimators for the cumulative entropy of these systems. The efficiency and reliability of these estimators were demonstrated using simulated analysis and subsequently validated using real data sets.</p>

Stability and reliability analysis of a non‐isolated high gain DC‐DC converter

AbstractThis paper investigates the stability and reliability analysis of a non‐isolated high‐gain DC‐DC converter. The proposed DC‐DC converter produces a high gain output voltage with a lower duty ratio and reduced voltage stress on the semiconductor switch. A reliability analysis is performed to predict the failure rate and lifetime of the individual components using the military handbook (MIL‐HDBK‐217F). A state space equation and small signal modeling of the proposed converter are derived to elucidate the performance of the proposed converter through stability analysis. A closed‐loop using PID controller is incorporated to attain the constant regulated output voltage during sudden parameter changes. The validation of the closed‐loop using the PID controller is verified with the wide range of variations in the different parameters, such as input voltage, load value, and reference voltage value. The laboratory‐based prototype is developed for the proposed converter and validated the performance with 250 W. The power density and efficiency of the proposed converter are 1.360 kW/L and 93%, respectively.

Fatigue crack driving force of railway bogie frames using rigid-flexible coupled dynamics: A case for beam model

The stress intensity factor is essential to determine the residual fatigue lifetime of cracked components. However, the traditional method used to determine the stress intensity factor is very difficult to characterize the dynamic behaviors of structure arising from the fatigue crack. This paper proposed a methodology to determine the dynamic stress intensity factor (DSIF) of a crack incorporating with the rigid-flexible coupled dynamics. Firstly, a rigid-flexible coupled dynamic model of cantilever beam representing the typical structure of bogie frame with a straight crack was developed based on SIMPACK platform. In the model, the equivalent spring - contact element was employed to model the contact behaviors of crack interface. Subsequently, the DSIF considering the crack closure effect was calculated by the node displacement extrapolation. The validity of proposed method was demonstrated through comparing the DSIF with those obtained by other analytical methods. The results suggest that the proposed methodology can characterize the closure effect of crack, and yield more accurate estimation for the DSIF. This method establishes a link between the multibody system dynamics and the fracture mechanics, which enable us to calculate the DSIF of crack under the operating condition using a rigid-flexible coupled dynamic model.

Correlation of Microstructural Events with Stress Corrosion Cracking Initiation Behaviour in Additively Manufactured Ni-Based Alloy 718: Microcapillary Electrochemical Technique Implementation

During the past decade, metal additive manufacturing has gained tremendous attention for the production of substitutive components for oil, gas, and nuclear industries as a consequence of the possibility of fabricating complex full-density components with fewer manufacturing processes compared to conventional methods. Laser powder bed fusion (L-PBF) is one of the most precise additive manufacturing techniques based on layer-by-layer production of the final component with a high-power laser beam. Most investigations to dat focus on comparing the mechanical properties of additively manufactured components with conventional counterparts. Process parameter optimization has been extensively studied for obtaining almost full-density components with comparable and in some cases even better mechanical performance compared to conventionally manufactured components. However, the corrosion and more specifically stress corrosion cracking (SCC) behaviour of L-PBF and in general, additively manufactured components has received less attention. Since the major concern in critical industries is to reduce the risk of SCC occurrence, the mechanistic study of the effect of various micro and submicron structural alterations on SCC risk assessment is of paramount importance.It is well recognized in the corrosion community that the most critical stage of SCC is related to the incubation/initiation stage. From the information gathered by various authors in the past decades, having a prolonged incubation/initiation stage of SCC could significantly increase the lifetime of components, which results from the balance between the formation and destruction reactions occurring in the passive layer-environment interface. Thus, it is essentially always the case that by retarding the initiation of cracks, we significantly increase the life cycle. Until now, traditional electrochemical techniques are not able to detect the SCC initiation stage as a consequence of the large surface area in contact with the solution and the shortcomings of the used electrochemical techniques. Thus, during the past decades, extensive research has been done on the crack propagation stage by utilizing various techniques and statistical models for the prediction of crack growth rate. This study reports for the first time the correlation of electrochemical polarization behaviour with the susceptibility of the material to SCC initiation. Such an approach fulfils the knowledge gap covering the initiation mechanism by proposing the microcapillary method as the method of choice for mechanistic analysis of initiation susceptibility.In the current investigation, various electrochemical techniques combined with high-resolution microstructural analysis were implemented to elucidate the importance of submicron characteristics of L-PBF fabricated components on SCC initiation risk assessment. L-PBF fabricated Ni-Fe-Cr based alloy 718 with a slight variation of laser power in the range of achieving full density was used for elucidating the effect of slight alterations in micro and nanostructure in corrosion and SCC initiation behaviour. It was found that even with a slight variation of L-PBF process parameters such as laser power, various alterations occurred in micron and submicron scale namely, a slight decrease in hardness, an increase in subgrain width, porosity, dislocation density, the density of nanovoids adjacent to subgrain boundaries, and presence of carbide particles. Such alterations consequently lead to significant electrochemical behaviour and SCC initiation susceptibility. Furthermore, the underlying mechanisms responsible for the observed variations in SCC initiation susceptibility had been explained as a consequence of alterations in subgrain width, dislocation density, intrinsic nano cavities density adjacent to subgrain boundaries, and the presence of nanoscale carbide particles adjacent to subgrain boundaries. From the obtained results, the microcapillary technique proved to be a very useful and powerful tool for assessing SCC initiation susceptibility for additive manufactured components with submicron scale structures.

Unveiling the Synergy of Coupled Gold Nanoparticles and J-Aggregates in Plexcitonic Systems for Enhanced Photochemical Applications.

Plexcitonic systems based on metal nanostructures and molecular J-aggregates offer an excellent opportunity to explore the intriguing interplay between plasmonic excitations and excitons, offering unique insights into light-matter interactions at the nanoscale. Their potential applications in photocatalysis have prompted a growing interest in both their synthesis and the analysis of their properties. However, in order to construct a high-performing system, it is essential to ensure chemical and spectral compatibility between both components. We present the results of a study into a hybrid system, achieved through the coupling of gold nanobipyramids with organic molecules, and demonstrate the strengthened photochemical properties of such a system in comparison with purely J-aggregates. Our analysis includes the absorbance and photoluminescence characterization of the system, revealing the remarkable plexcitonic interaction and pronounced coupling effect. The absorbance spectroscopy of the hybrid systems enabled the investigation of the coupling strength (g). Additionally, the photoluminescence response of the J-aggregates and coupled systems reveals the impact of the coupling regime. Utilizing fluorescence lifetime imaging microscopy, we established how the photoluminescence lifetime components of the J-aggregates are affected within the plexcitonic system. Finally, to assess the photodegradation of J-aggregates and plexcitonic systems, we conducted a comparative analysis. Our findings reveal that plasmon-enhanced interactions lead to improved photostability in hybrid systems.

Positron Trapping Rate in Some Ferroelectrics, Semiconductors and Glasses

This paper presents comparative results of positron spectroscopy studies in ferroelectrics, semiconductors and glasses. The positron lifetime spectroscopy study is focused on the investigation of the positron trapping rate in the ferroelectrics, the Triglycine Sulphate (TGS) (NH3CH2COOH)3H2SO4, Rochelle Salt (RS) NaKC4H4O64H2O and Potassium Dihydrogen Phosphate (KDP) KH2PO4 structures, semiconductors and glasses. The positive positron charge opens the possibility for determining the changes in charge states in technologically important order-disorder ferroelectrics. The positron lifetime spectroscopy (PLS) results show that the second lifetime component as a function of temperature in order-disorder ferroelectrics TGS, RS and KDP is due to the positron trapping in negatively charged defects of ferroelectric. The PLS analysis has been applied for examination of positron trapping in the electronicdefect structure in selected ferroelectrics materials, semiconductors and glasses.

Metabolism in the large intestine wall after injury of the thoracic spinal cord (experimental study)

Ailm: to assess metabolic processes in the serous layer of the large intestine in the acute period of spinal injury.Materials and Methods: the experiment was carried out on laboratory animals — Wistar rats (n = 20). Spinal injury was simulated by complete transection of the spinal cord at the level of Th5-Th6 vertebrae. Metabolic changes in the intestinal wall were assessed before injury, 3 and 24 hours after spinal cord transection. Metabolism was assessed in vivo using fluorescence time-resolved macroimaging technology (macroFLIM) by autofluorescence in the spectral channel of the metabolic cofactor NAD(P)H.Results: a significant (p = 0.041) increase in the mean fluorescence lifetime (τm) by 12% and the lifetime of the long component (τ2) of the NAD(P)H cofactor by 13% (p = 0.008) was detected 24 hours after injury. MacroFLIM showed an increase in the intensity of metabolism in the large intestine wall.Conclusion: for the first time in an in vivo experiment, it has been shown that the acute period of spinal injury is accompanied by an increase in metabolic activity in the tissues of the large intestine. The revealed phenomenon confirms the role of the large intestine in compensatory reactions to spinal injury and open up new possibilities for therapy in the acute period of spinal cord injury.

Identification of ortho-positronium annihilation sites in Y zeolites by positron lifetime measurements in different environments

The annihilation sites of ortho-positronium formed by positrons incident on Y zeolites with different Si/Al ratios are investigated by positron annihilation lifetime spectroscopy in different environments. Comparison of the measured ortho-positronium lifetimes by exposure of the zeolites to argon, nitrogen, water or vacuum enables us to determine the annihilation process and the specific annihilation site within the zeolite samples. The third lifetime component is ascribed to ortho-positronium pick-off annihilation in or around the apertures of the sodalite cage and in the connecting channels, and is reduced in water because of the physisorbed molecules that hinder the ortho-positronium mobility. The longest fourth lifetime component is attributed to ortho-positronium self-annihilation in the interparticle gaps, but is significantly suppressed in the presence of polar molecules, which suggests a contribution from ortho-positronium pick-off annihilation in the supercage.