Time-dependent Influence Research Articles

The time dependent influence of curvature and topography of biomaterials in the behavior of corneal endothelial cells.

Among the different layers of the cornea, the corneal endothelium, which is composed of corneal endothelial cells (CEC), plays a key role in the maintenance of cornea transparency. Based on the donor shortages and the limitations associated with transplantation, in this work we have developed collagen hydrogels with different patterned structures on the surface to provide topographies in ranges similar to the natural environment that CEC sense. This aimed at stimulating cells to maintain a typical CEC phenotype and provide alternatives to corneal transplantation. In this sense, we have elaborated curved collagen hydrogels (concave and convex) with three different topographies (50, 200 and 300µm grooves), with the help of 3D printed mold and replicating the mold with the collagen hydrogel, onto which CEC were cultured in order to analyze its behavior. Flat hydrogels were used as controls. Cell morphology, cell circularity and gene expression of ATP1A1 and ZO-1 genes were analyzed after 3 and 6days. Results showed an effect of the curvature and the topography compared to flat collagen hydrogels, showing higher expression of ZO-1 and ATP1A1 in curved non-patterned hydrogels at day 3. The patterned hydrogels did not have such a significant effect on gene expression compared to flat hydrogels, showing stronger effect of the curvature compared to the topography. The effect was opposite at day 6, showing higher gene expression at days 6 on the patterned hydrogels, especially for the ZO-1 gene. The gene expression results were in accordance with the cell morphology observed at the different time points, showing circularities closer to hexagon like morphology at shorter time points. Overall, this platform can serve as a system to culture cell under proper environment to further be able to transplant a CEC monolayer or to allow transplantation of thin collagen layers with cultured CEC.

Pozzolanic metakaolin reactivity: Time-dependent influence of calcium hydroxide, alkali hydroxides, and sulfates

In the quest for environmentally sustainable binders within the construction industry, metakaolin (MK) has emerged as a highly promising material. Its reactivity and hardening performance encompass a wide range of applications, spanning from lime to cement-based materials. This performance is primarily underpinned by the pozzolanic reaction with calcium hydroxide (CH), leading to the formation of various calcium aluminate silicate hydrates. The intricacies of the hydration kinetics and resultant reaction products hinge on several factors woven into the specifics of the binder type. This study investigates the influence of CH availability, explored through initially mixed MK/CH weight ratios of 0.33 and 1.0. Furthermore, the study examines the impact of introducing alkali hydroxides (KOH and NaOH) and/or sulfates (K2SO4 and Na2SO4) on the pozzolanic reactions. Short-term analysis employed inductively coupled plasma optical emission spectrometry (ICP-OES), and pH measurements for pore solution as well as isothermal calorimetry, and in-situ X-ray diffraction (XRD) on paste samples. Long-term investigations extended to 245 days at 40 °C, incorporating XRD, thermogravimetric (TGA) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX). Results provide insights into the kinetics of phase assemblage and compositions of C-A-S-H gels, highlighting the transformation of metastable C2ASH8 and C4AH13 to stable Si-rich hydrogarnet phases, incorporating sulfate, under excess CH conditions. Higher MK/CH enriches Si/Ca, Al/Ca, enhancing C-A-S-H gels, while KOH addition further boosts Al/Ca ratios.

Intraoperative traction has a negligible time-dependent influence onpatient-reported outcomes after hip arthroscopy: a cohort study.

The aim of this study is to determine if post-operative patient-reported outcome measures (PROMs) are influenced by hip arthroscopy traction duration. Patients from a local prospective hip arthroscopy database were retrospectively analyzed. Four hip-specific PROMs were utilized: modified Harris Hip Score (mHHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Specific (HOS-SS), and international Hip Outcome Tool (iHOT). PROMs were collected pre-operatively and 6 months, 1 year and 2 years post-operatively. Two cohorts were created based on a cut-off corresponding to the 66th percentile for our patient cohort. Analyses were completed for each PROM at each post-operative interval with univariable statistics. Multivariable statistics were examined to identify the variables that were predictive of achieving post-operative minimal clinically important difference (MCID) at the 2-year follow-up. Overall, 222 patients met the inclusion criteria. The mean age was 32.4 ± 9.4 years, and 116 (52.3%) were female. The average traction time of the study population was 46.1 ± 12.9 min. A total of 145 patients were included in the short traction cohort (65%) with traction times of <50 min (66th percentile). No significant differences were found regarding PROM scores or MCID achievement rates between both cohorts at any post-operative period. In multivariable analyses, achievement of MCID was predicted by a decrease in traction time for all PROMs and pincer-type resection for mHSS, HOS-ADL and iHOT. There was no difference in PROMs and MCID achievement between longer and shorter traction time cohorts. On multivariable analysis, a decrease in traction time is predictive of MCID for all PROM scores and pincer-type resection was predictive of MCID for most PROM scores. Level of evidence: Level III, cohort study.

Delhi urbanization footprint and its effect on the earth’s subsurface state-of-stress through decadal seismicity modulation

Urban land and its expansion have profoundly impacted the global environment, including the stress change in the earth’s subsurface, even though urban land is a small fraction of the global land surface. Divulging such effects has never been more important, given the role of stress in determining the safety of the urban population against earthquakes. However, knowledge of this time-dependent non-linear effect of urbanization on the subsurface remains in the gray area. This study focuses on the area surrounding Delhi, the capital city of India, to understand the relative contribution of the building load created by rapid urbanization in exacerbating the subsurface state-of-stress. The results highlight that, since 2010, the modulation in the seismicity rate and the stability of basement thrust faults is linked not only to urbanization but also to decadal groundwater storage. Mounting evidence suggests that the rapid urbanization, and the resulting non-tectonic horizontal compression, stabilize faults in the Aravalli Delhi belt, which are destabilized due to the extensive groundwater extraction. This affects the decadal seismicity trend around the Aravalli Delhi fold belt. Nonetheless, the magnitude of this time-dependent deformation influence on the seismicity modulation remains uncertain. The findings from this study quantify the geomechanical impacts of urbanization in the Delhi area for the first time.

The Influence of the Prestressing Level of the Fully Threaded Anchor Bar on the Corrosion Rate

The article presents experimental research on the corrosion of prestressing steel bars with denotation CKT (fully threaded anchor bars), which are composed of high-quality prestressing steel of the grade Y 1050 (1050 MPa). The experiment was performed using an electrochemical accelerated test. The aspects of the electric current value influence, time dependence on the degree of corrosion, and especially the influence of the prestressing level in the prestressing steel bars on the degree of corrosion were observed and examined. The results of the experiment showed that if the sample was in a stressed state, its degree of corrosion increased. Specifically, for the maximal stress equal to 90% of the tensile strength, the corrosion degree was increased by approximately 7.3%, in comparison to the unstressed specimen. In this case, a 7.3% corrosion degree corresponds to a weight loss of 350 g. The theoretical degree of corrosion was calculated using Faraday’s Law, which allowed the prediction of a rough estimate of the corrosion degree obtained with known input data. The experimental results showed that there was no apparent difference in the corrosion morphology of the sample during the same time-dependent corrosion influence at the same prestressing level in the sample with the same electric current value.

Life prediction method based on damage mechanism for titanium alloy TC4 under multiaxial thermo-mechanical fatigue loading

In this paper, a life prediction method based on damage mechanism for titanium alloy TC4 under multiaxial thermo-mechanical fatigue loading is proposed. Temperature and time dependent influence factors are proposed and introduced into the strain amplitude-life curve method to consider the temperature and time dependence of damage, respectively. The increase in fatigue and oxidation damages caused by tensile mean stress and non-proportional additional hardening is expressed by the mean stress in Macaulay brackets and by using a multiaxial damage parameter, respectively. A fast cracking influence factor is proposed to consider the influence of fast cracking of materials caused by the combined action of high temperature, tensile stress and shear stress on damage behavior. The material constants are identified by test data under uniaxial and proportional loadings, and are further used for prediction under non-proportional loading. The failure life results of uniaxial isothermal fatigue tests with and without dwell time, uniaxial and multiaxial thermo-mechanical fatigue tests are used to verify the proposed method. The value of the scatter band of life prediction result is less than ± 2, as well as the maximum and mean relative errors between predicted and experimental strain amplitudes are 18.49% and 6.54%, respectively.

The Activated Sludge Flow Characteristics Required for The Design Of Pressure Pipeline

In This research studied the effect of the sludge characteristics such as settling propertiese and concentration of solids in the sludge on the flow propertiese of heterogeneous sewage sludges. The non-Newtonian (pseudoplastic ) and time-dependent (thixotropic) influence on the rheological characteristics of sewage sludge was calculated experimentally. Depending on these characteristics and during several experiments an empirical method has been developed to calculate the head losses in pressure pipes which convey these sludges under laminar flow conditions. The results showed that the torque (T) and shear stress (τ) decrease with time at constant rotational speed,and the time-independent behaviour was approached after 900sec.,where no further decrease in shear stress was observed after 900s. A relations has been plotted between the flow rate (Q) and maximum,minimum head losses by means of a design example , in addition to the head loss gradient decay along a pipeline and between Euler and Reynolds numbers .

Effect of curing compounds on the quality of passive layer development under varying oxygen concentration for RC structures in the course of early curing of concrete

• Quality of passive layer development and corrosion progress in reinforced concrete. • Time dependent influence of varying oxygen through the use of various curing compounds. • Varying water-to-cement ratios and different curing environments. • Improved/new/novel procedure for curing compound application. The quality of passive layer development and corrosion progress in reinforced concrete as influenced by varying the oxygen concentration at the initial stages of the curing period was investigated. Specimens with various curing compounds (paraffin emulsion based, bitumen based, and wax based), varying water-to-cement ratios, and different curing environments (air, submerged, and sealed) were used as a mode for varying the amount of oxygen. The experimental measurements made it possible to understand satisfactorily the time dependent effect of the concentration of oxygen on protective layer development and the successive rusting of steel reinforcement in different specified environments. For the unsealed specimens in laboratory environment cured initially using wet burlap with free oxygen availability throughout the curing phase gave lowest corrosion rates (0.1 μA/cm 2 and corrosion potential of −240 mV CSE measured after 276 days) indicating the formation of a strong passive layer as sufficient amount of oxygen was present in the vicinity of the specimens. However, the curing compound specimens that were completely sealed to limit oxygen availability showed highest corrosion rates (0.23 μA/cm 2 and corrosion potential of −301 mV CSE recorded after 276 days) indicating the development of a fragile protective film in the start which resulted in the maximum rusting of rebars afterwards. The other curing compound specimens that were subjected to varying levels of oxygen availability at the initial stage of curing gave intermediate results. It is believed that the results obtained in this study are novel and should lead to an improved passive layer development on the surface of rebar by adopting an improved procedure for curing compound application (material and geometry) incorporating humidity preservation along with oxygen accessibility.

Numerical simulation of elastic buckling in 3D concrete printing using the lattice model with geometric nonlinearity

This paper explores buildability quantification of randomly meshed 3D printed concrete objects by considering structural failure by elastic buckling. The newly proposed model considers the most relevant printing parameters, including time-dependent material behaviors, printing velocity, localized damage and influence of sequential printing process. The computational uniaxial compression tests were first conducted to calibrate age-dependent elastic modulus and yield stress. Subsequently, analyses of the 3D printing process of a free wall structure and a square layout were performed. The model can reproduce the asymmetry of buckling failure accurately and the predicted critical printing height is in excellent agreement with experimental data from the literature. It can be concluded the combined effect of material variability and non-uniform gravitational loading due to sequential printing process resulted in structural failure during 3D concrete printing. Using this model, printing parameters can be optimized and a suitable printing scheme can be devised to improve structure buildability.

ANN-Based Dynamic Prediction of Daily Ground Settlement of Foundation Pit Considering Time-Dependent Influence Factors

Accurately and dynamically predicting ground settlements during the construction of foundation pits is pivotal to the understanding of the potential risk of foundation pits and, therefore, enables constructors to take timely and effective actions to ensure the construction safety of foundation pits. Existing settlement prediction methods mainly focus on the prediction of the maximum ground settlements based on static influence factors, such as soil properties and the geometry of foundation pits. However, these methods are unable to be applied to the prediction of daily ground settlements in a direct way because daily ground settlements can be affected by many time-dependent influence factors, and an accurate prediction of daily ground settlements should take into consideration such factors. To address this problem, this paper proposes an artificial neural network-based daily ground settlement prediction method, where both static and time-dependent influence factors, as well as previous settlement monitoring data, are considered in the optimum artificial neural network. The proposed method is validated using data collected from a real cut-and-cover highway tunnel project in western Hangzhou, China. The results demonstrate that time-dependent influence factors and previous settlement monitoring data play vital roles in establishing an optimum artificial neural network for the accurate prediction of daily ground settlement.

Is freeze-drying an alternative to solvent exchange for the hydration stop of cementitious suspensions?

In order to understand the rheological properties of cementitious suspensions at early stages, among other phases, the formation of ettringite and its time-dependent influence, whether by amount or morphology, has to be examined in detail using a suitable method to stop the hydration process. It is state-of-the-art to exchange water with isopropanol, however, the water initially remains in the system possibly leading to reduced time resolution. Our group raised the question if freeze-drying or the combination of the water-isopropanol exchange with subsequent freeze-drying might be a suitable technique to achieve an almost complete hydration stop at any time. Recently, it was shown under which circumstances low-pressure characterization techniques can be employed without destroying the samples due to loss of crystal bound water. Here, by implementing these recent results, we show under which circumstances freeze-drying indeed can be employed as fast hydration stop method.

Sensitivity analysis and Bayesian calibration of a dynamic wind farm control model: FLORIDyn

FLORIDyn is a parametric control-oriented dynamic model suitable to predict the dynamic wake interactions between wind turbines in a wind farm. In order to improve the accuracy of FLORIDyn, this study proposes to calibrate the tuning parameters present in the model by employing a probabilistic setting using the UQ4WIND framework. The strategy relies on constructing a surrogate model (based on polynomial chaos expansion), which is then used to perform both global sensitivity analysis and Bayesian calibration. For our analysis, a nine wind turbine configuration in a yawed setting constitutes the test case. The results of sensitivity analysis offer valuable insight into the time-dependent influence of the model parameters onto the model output. The model parameter tied to the turbine efficiency appear to be the most sensitive parameter affecting the model output. The calibrated FLORIDyn model using the Bayesian approach yield predictions much closer to the measurement data, which is equipped with an uncertainty estimate.

Mean-Field Selective Optimal Control via Transient Leadership

A mean-field selective optimal control problem of multipopulation dynamics via transient leadership is considered. The agents in the system are described by their spatial position and their probability of belonging to a certain population. The dynamics in the control problem is characterized by the presence of an activation function which tunes the control on each agent according to the membership to a population, which, in turn, evolves according to a Markov-type jump process. In this way, a hypothetical policy maker can select a restricted pool of agents to act upon based, for instance, on their time-dependent influence on the rest of the population. A finite-particle control problem is studied and its mean-field limit is identified via varGamma -convergence, ensuring convergence of optimal controls. The dynamics of the mean-field optimal control is governed by a continuity-type equation without diffusion. Specific applications in the context of opinion dynamics are discussed with some numerical experiments.

Measurements of the thermal conductivity of reference liquids using a modified transient hot-wire needle probe

Many power generation processes feature some type of working fluid that plays a critical role in the transfer of heat throughout the system. To optimize thermal efficiencies, an accurate characterization of the temperature-dependent thermal conductivity of the fluid is needed. This study develops a time-domain Modified Transient Hot-wire Needle Probe to overcome phenomena that have impaired traditional measurement techniques when the fluid is both corrosive and at an elevated temperature. First, the physical design of the instrument is presented to demonstrate features that limit interference from corrosion, electrical conduction, and convective and radiative heat transfer. Next, a governing equation for 1D (radial) heat conduction is fully developed using the thermal quadrupoles technique. A finite-element study is performed for validation. A sensitivity analysis is done to assess the time-dependent influence of critical parameters in the governing equation for several samples. Finally, thermal conductivity measurements are presented for seven different liquid substances by fitting the thermal model to experimental data across a range of temperatures. Reference correlations are included for comparison. The sample thermal conductivity and ambient temperature of the experimental conditions range from 0.125–16.5WmK and 10–400∘C, respectively. The total uncertainty, comprised of both the experimental design and fitting process, of all measurements is quantified.

Time-dependent influence of high glucose environment on the metabolism of neuronal immortalized cells

Mitochondria are organelles of bacterial origin historically identified as the cell power plant. In addition to energy, mitochondria produce reactive oxygen species and they have been found to have a key role in cell defense regulation, cell stress and damage. All the investigations regarding the nature of the molecules mediating these processes include compounds from mammalian cell metabolism. We hypothesize that the bacterial origin of mitochondria brings them to produce small fermentation products when cell is subjected to stress. In this work we studied the effect of hyperglycemia on the metabolome of hippocampal HN9.10e neurons, an in vitro model of one of the most vulnerable regions of central nervous system. Targeted metabolites were analyzed in the cell culture medium by liquid chromatography – diode array detection and headspace – gas chromatography – mass spectrometry. Twenty-two low molecular weight metabolites were identified and quantified in the growth medium of the cells, treated with 25, 50 or 75 mM glucose, sampled along 8 days to mimic a prolonged hyperglycemia. The results of statistical analysis showed the clear impairment of neuronal metabolism already after 48 h, represented by a significant reduction of the metabolic activity, together with the production of typical fermentative compounds.

Perovskite Nanoparticles as an Electrochemical Sensing Platform for Detection of Warfarin.

Chemically prepared PrAlO3 perovskite nanoparticles (NPs) were applied for the electrochemical detection of warfarin, which is commonly utilized for preventing blood clots, such as in deep vein thrombosis. PrAlO3 perovskite NPs were synthesized by the co-precipitation process at environmental conditions. Crystallographic structure, phase purity, morphological structure, thermal stability, optical properties, and electrochemical characteristics were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, UV-visible analysis, and cyclic voltammetry techniques. TEM micrographs showed the highly crystalline structure, smooth surface, irregular shape, and size of nanocrystalline particles with an average size of 20–30 nm. Particularly crystalline perovskite NPs were pasted on glassy carbon electrodes (GCE) to electrochemically detect the warfarin contents in liquid samples. The fabricated electrode was electrochemically characterized by different parameters such as different potential, scan rates, same potential with seven consecutive cycles, time response, real-time sample analysis, and as a function of warfarin concentration in phosphate buffer solution (0.1 M PBS, pH 7.2). The electrochemical electrode was further verified with various potentials of 5, 10, 20, 50, 100, and 150 mV/s, which exhibited sequential enhancements in the potential range. For detecting warfarin over a wide concentration range (19.5 µM–5000 µM), the detection devices offered good sensitivity and a low limit of detection (19.5 µM). The time-dependent influence was examined using chronoamperometry (perovskite NPs/GCE) in the absence and presence of warfarin at four distinct voltages of +0.05 to +1.2 V from 0 to 1000 s. The repeatability and reliability of the constructed electrochemical sensing electrode were also evaluated in terms of cyclic response for 30 days, demonstrating that it is substantially more reliable for a longer period. The fabricated perovskite NPs/GCE electrodes could be employed for the rapid identification of other drugs.

Discoloration of AISI 420 stainless steel in dependence of inter layer time during Laser-based Powder Bed Fusion

Parts built by laser-based powder bed fusion (PBF-LB) experience intervals of heating and cooling during the powder deposition and the selective melting of successive layers. Short time intervals of cooling can lead to heat accumulation resulting in discoloration of AISI 420 (X20Cr13) stainless steel parts. Discoloration occurs due to the formation of oxide layers, which negatively affect the corrosion resistance. This process is determined by the time-dependent influence of temperature and oxygen.Therefore, this study investigates effects of varied inter layer time on mechanical PBF-LB part properties and surface characteristics to prevent discoloration. EDX is used to analyze the chemical composition with regard to the chromium content as an indicator of reduced corrosion resistance. The results emphasize the need for implementing an minimum inter layer time greater than 12 s to prevent discoloration during the PBF-LB process with a layer thickness of 20 µm and a volume energy density of 113.3 J/mm³.

Time-dependent influence of infliximab on hemodynamic responses and cardiac injuries of isoproterenol-induced myocardial infarction in rats

Immune-induced inflammation plays an important role both in aggravating and healing of post myocardial infarction (MI) injuries. Potent anti-inflammatory and local immunomodulatory activity of infliximab has been suggested to have modulating effects on immune responses after MI. The aim of the present study was to evaluate the efficacy of infliximab on hemodynamic responses and myocardial injuries following isoproterenol-induced myocardial infarction. Male Wistar rats, weighting 260 ± 20 g were assigned into ten groups (n = 6) of saline (normal saline), infliximab (7 mg/kg), isoproterenol (100 mg/kg for two consecutive days), and isoproterenol plus infliximab (30 min after the second injection of isoproterenol). The heart tissues and serums were analyzed 24, 48, 72, and 96 h post-MI and hemodynamic parameters, histopathological changes, malondialdehyde (MDA), Total antioxidant capacity (TAC), lactate dehydrogenase (LDH), and lactate levels were assessed in the respective groups. Infliximab partially improved hemodynamic depression in the first days after MI, but the heart became more suppressed later. A similar result also obtained at the MDA tissue levels but not serum levels. Anti-inflammatory effects of Infliximab may improve cardiac function and prevent heart tissue injury early after MI; however, it can worsen the condition later by inhibiting compensatory reactions such as cardiac remodeling and tissue repair.

Memory-dependent generalized thermoelasticity with finite wave speeds

The present article deals with the question: how time dependent non-locality influence the domain of dependency of thermal signals in solids? In order to establish the hypothesis “domain of influence” in an isotropic medium, based on the temperature-rate dependent thermoelasticity (TRDTE) theory, a thermodynamic consistent model is formulated by incorporating memory-dependent derivative (MDD). Firstly, the domain of influence theorem is established followed by a domain of dependence inequality and it certifies that for a finite time t>0 a solution of a given thermo-dynamical problem, corresponding to the data defined in a bounded support, vanishes outside a suitably defined bounded domain D*(t). It physically interprets that an initial perturbation of a bounded thermo-elastic domain generates thermal signals which for any t>0 can not occupy the whole space, i.e. it propagates with a finite speed. Finally, a two-dimensional thermoelastic problem in the isotropic medium is considered for a supporting visualization of the domain of influence theorem of the memory-dependent generalized thermoelasticity theory.

A Resting-State fMRI Study of Static and Dynamic Graph Analysis for Seafarer’ Brain

In order to explore the influence of the marine environment on the topological properties of seafarers’ brain functional connectivity networks and the specificity of the topological structure of seafarers’ brain compared with that of non-seafarers, the fMRI data of 33 seafarers before and after sailing as well as the data of 33 non-seafarers are used to explore the differences of topological structure between them from both static and dynamic brain functional connectivity networks among the 90 brain regions of AAL template in this study. The results show that the marine environment has a time-dependent influence on the topological structure of seafarers’ brain functional networks, especially for the dynamic brain functional networks, which means that some topological changes can be recovered in a relatively short time, while others may have long-term effects to form the unique topological characteristics of brain functions for seafarers. These results have an important reference value to further explore seafarers’ professional brain plasticity.