Dwell Time Research Articles

Long-Term Tunneled Hemodialysis Catheters: Achieving Efficiency Through Tip Position Optimization

This retrospective study assesses the influence of tunneled hemodialysis catheter tip location and lateralization on catheter-related complications, including dysfunction and catheter-related bloodstream infection. Using data from 162 patients who underwent catheter placement between January 2017 and December 2020, postoperative chest X-rays and clinical records were reviewed. Outcomes were assessed based on catheter removal duration and complication incidence. Out of 177 catheter placements, 56 (32%) patients experienced complications during an average 530-day follow-up. Catheters placed in the superior vena cava (SVC) exhibited more severe complications with shorter dwell times compared with those in the pericavoatrial junction (pCAJ) or right atrium (RA). Moreover, complication rates were significantly higher (P<0.01) in the SVC (1.91 per 1000 catheter days) compared with the pCAJ (0.54) or RA (0.47). Lateralization (right or left internal jugular vein) did not significantly affect the complication rates (0.60 vs. 0.58; P=0.90). However, in subgroup analysis, a significantly higher complication rate was observed for catheters with tips inserted from the left side into the SVC than for those inserted from the right side (6.6 vs. 1.5; P<0.01). Catheters with tips in the SVC exhibited more severe complications than those in the pCAJ or RA, with left-side insertion of SVC-tipped catheters resulting in significantly higher complication rates compared with right-side insertion. These findings highlight the importance of optimal catheter tip positioning in long-term hemodialysis care to minimize complications and enhance patient outcomes.

Fast compressive Raman micro-spectroscopy to image and classify microplastics from natural marine environment

The fast and reliable detection of micron-sized plastic particles from the natural marine environment is an important topic that is mostly addressed using spontaneous Raman spectroscopy. Due to the long (>tens of ms) integration time required to record a viable Raman signal, measurements are limited to a single point per microplastic particle or require very long acquisition times (up to tens of hours). In this work, we develop, validate, and demonstrate a compressive Raman technology using binary spectral filters and single-pixel detection that can image and classify six types of marine microplastic particles over an area of 1 mm2 with a pixel dwell time down to 1.75 ms/pixel and a spatial resolution of 1 µm. This is x10–100 faster than reported in previous studies.

The Role of MXene Surface Terminations on Peptide Transportation in Nanopore Sensing.

Nanopores with two-dimensional materials have various advantages in sensing, but the fast translocation of molecules hinders their scale-up applications. In this work, we investigate the influence of -F, -O, and -OH surface terminations on the translocation of peptides through MXene nanopores. We find that the longest dwell time always occurs when peptides pass through the Ti3C2O2 nanopores. This elongated dwell time is induced by the strongest interaction between peptides and the Ti3C2O2 membrane, in which the van der Waals interactions dominate. Compared to the other two MXene nanopores, the braking effect is indicated during the whole translocation process, which evidence the advantage of Ti3C2O2 in nanopore sensing. Our work demonstrates that membrane surface chemistry has a great influence on the translocation of peptides, which can be introduced in the design of nanopores for a better performance.

Metallurgical Characterization of Micro Friction Stir Spot Welding (μFSSW) Parameters on Similar Materials AA1100

The Micro Friction Stir Spot Welding (μFSSW) process is a metal plate welding technique with a relatively thin plate thickness. The advantages of this welding are the higher quality of the weld and the relatively low deformation. This study aimed to determine the effect of depth of penetration, dwell time, and tool geometry on the trend of material flow on the macro-structure of the welds produced in μFSSW technique using AA1100 thin aluminum plates. In this study, the parameters that are changed are the depth of the chisel, dwell time, and tool geometry. In this study, the parameters of the penetration depth were divided into 500 microns, dwell time was split into three lengths of time (300 ms, 500 ms, and 700 ms), and tool geometry was divided into two types of tool geometries (tool-1 and tool-2). In addition, the macro test was carried out to determine the depth of the weld, contour profile, and stretch macrostructure. The results of the macro test will be used to analyze the material flow relationship in each weld zone on the welding results of all existing parameters. Based on the results of the study, the effect of depth of penetration, dwell time, and tool geometry on the weld depth and metallography (hook width, hook height, and effective top sheet thickness) of welds using AA1100 thin plates is influential along with various tool geometries and the deeper the weld penetration and the longer stirring time, although the results are not always directly proportional.

Effect of multi-injection strategy on characteristics of methanol-fueled direct injection spark ignition engine

Present paper numerically investigates the effect of injection strategy and start of injection (SOI) timing on in-cylinder flow, air–fuel mixing, fuel distribution near spark plug, engine performance, and exhaust emissions for highly stratified methanol-fueled, multi-injection, direct injection spark ignition engine having high compression ratio. SOI is kept constant at −23° crank angle (CA) after top dead center (ATDC) with a spark timing (ST) of −2° crank angle (CA) ATDC. Mass of fuel is divided into pilot and main injection ports having pilot to main fuel injection mass ratio of 1:1, 1:2, and 1:3 at 0° and 2° dwell times between main and pilot injections. As the quantity of fuel in main injection increases, pressure rise rate increases, which results in higher in-cylinder pressure and higher rate of burning that gives higher apparent heat release. Due to higher peak pressure rise rate and faster burning in the case of 2° crank angle (CA) dwell time, shorter combustion duration is achieved compared to 0° crank angle (CA) dwell time. In the case of multi-injection, faster burning rate enhanced in-cylinder temperature; therefore, nitrogen oxides (NOx) emissions are higher. Pilot to main fuel mass ratio of 1:3 has resulted highest indicated thermal efficiency, lowest specific fuel consumption, lowest soot, and carbon monoxide (CO) emissions.

Long-Term Ultrasound Twinkling Detectability and Safety of a Polymethyl Methacrylate Soft Tissue Marker Compared to Conventional Breast Biopsy Markers—A Preclinical Study in a Porcine Model

ObjectiveWe have studied the use of polymethyl methacrylate (PMMA) as an alternative biopsy marker that is readily detectable with ultrasound Doppler twinkling in cases of in vitro, ex vivo, or limited duration in vivo settings. This study investigates the long-term safety and ultrasound Doppler twinkling detectability of a PMMA breast biopsy marker following local perturbations and different dwell times in a 6-mo animal experiment. MethodsThis study, which was approved by our Institutional Animal Care and Use Committee, involved three pigs and utilized various markers, including PMMA (Zimmer Biomet), 3D-printed, and Tumark Q markers. Markers were implanted at different times for each pig. Mesh material or ethanol was used to induce a local inflammatory reaction near certain markers. A semiquantitative twinkling score assessed twinkling for actionable localization during monthly ultrasounds. At the primary endpoint, ultrasound-guided localization of lymph nodes with detectable markers was performed. Following surgical resection of the localized nodes, histomorphometric analysis was conducted to evaluate for tissue ingrowth and the formation of a tissue rind around the markers. ResultsNo adverse events occurred. Twinkling scores of all markers for all three pigs decreased gradually over time. The Q marker exhibited the highest mean twinkling score followed by the PMMA marker, PMMA with mesh, and Q with ethanol. The 3D-printed marker with mesh and PMMA with ethanol had the lowest scores. All wire-localized lymph nodes were successfully resected. Despite varying percentages of tissue rind around the markers and a significant reduction in overall twinkling (p < 0.001) over time, mean PMMA twinkling scores remained clinically actionable at 6 and 5 mo using a General Electric C1-6 probe and 9L-probe, respectively. ConclusionsIn this porcine model, the PMMA marker demonstrates an acceptable safety profile. Clinically actionable twinkling aids PMMA marker detection even after 6 mo of dwell time in porcine lymph nodes. The Q marker maintained the greatest twinkling over time compared to all the other markers studied.

Optimization of the Symmetrical SVPWM for Three-Level T-Type Inverters With Unbalanced and Oscillated Neutral-Point Voltages

The symmetrical space-vector pulse-width-modulation (SVPWM) has been widely adopted in three-level (3L) T-type inverters due to its low current harmonics and high linear modulation index. However, when faced with unbalanced and oscillated neutral-point (NP) voltages, extra current harmonics will be generated. In this paper, a new solution is provided. Other than adopting the existing strategies for balancing the NP voltage, the symmetrical 3L SVPWM is optimized to work with unbalanced and oscillated NP voltages. Firstly, the vectors are idealized, based on which ideal dwell times are obtained by an analytical simplified symmetrical 3L SVPWM. Then, a dc-zero-sequence component is calculated and injected to maximize the linear modulation index, and the real dwell times are further derived after the adjustment according to the ‘volt-second balance’ principle. In addition, a control strategy is investigated to actively adjust the NP voltage. Finally, the optimized symmetrical 3L SVPWM is verified by comparative experiments, showing its low current harmonics with unbalanced and oscillated NP voltages.

An Investigation of the Effect of Wide Range Gamma Radiation from Nanoindentation of the SAC305 Solder Alloy

This study utilises nanoindentation testing to investigate the impact of varying gamma radiation doses on the micromechanical properties of Sn-Ag-Cu (SAC) alloy. Specifically, the focus is on evaluating changes in hardness, reduced modulus, and creep behaviour. The stencil-printed method and reflow soldering process were employed to apply the SAC solder paste and create solder joints on the surface of the printed circuit board. The soldered samples underwent exposure to gamma radiation at different doses, specifically 5, 50, 500, 5000, and 50000 Gy. The solder received in its original state was used as the control sample. Subsequently, the samples were subjected to a nanoindentation test in order to ascertain the correlation between load and depth, depth and dwell time, when exposed to radiation. The load-depth curve results indicate that there is a transition in the behaviour of solder joint materials from elastic to plastic deformation as the radiation dose increases. A finding has been made indicating that exposure to gamma radiation has the potential to induce a transition in the behaviour of SAC from an elastic state to a plastic state. The exposure to radiation doses has been found to induce changes in the atomic arrangement and structural properties of materials, leading to an increase in their hardness values. Nevertheless, it was observed that with increasing radiation doses up to 500 Gy, there was a noticeable decrease in the hardness value, which can be attributed to the occurrence of softening behaviour. Exposure to a high dose exceeding 5000 Gy leads to atomic displacement and transmutation products, subsequently resulting in plastic deformation. The stress exponent value signifies the occurrence of the deformation mechanism in solder material when exposed to gamma radiation. The study revealed that there was a shift in the deformation mechanism from grain boundary sliding to dislocation climb as the radiation dose increased from low to high levels.

Bumpless transfer control for switched impulsive positive systems with [formula omitted]-gain performance

This paper investigates the problem of bumpless transfer control for switched impulsive positive systems with L1-gain performance. For switched impulsive positive systems, the control bump is brought from both switching behavior and impulsive effects. First, the concept of bumpless transfer performance is proposed by imposing magnitude constraints on the control signal to measure the level of bumpless transfer in the switched impulsive positive system. Then, based on a new class of multiple piecewise-continuous copositive Lyapunov function, a tighter mode-dependent average dwell time switching signal bound and bumpless transfer controller are designed to realize positive property, bumpless transfer and L1-gain performance of the closed-loop systems. Finally, the feasibility and superiority of the proposed control strategy are illustrated by simulations.

Primary anastomosis closure after endoscopic ultrasound-directed transgastric intervention.

Background and study aims Endoscopic ultrasound-directed transgastric intervention (EDGI) is a technique that creates an anastomosis between the gastric pouch or jejunum to the excluded stomach in Roux-en-Y gastric bypass (RYGB) anatomy to allow access to the pancreaticobiliary system. Thus far, management of anastomosis closure at the time of lumen-apposing metal stent (LAMS) removal has varied widely. This study aimed to assess the efficacy of primary closure at the time of LAMS removal using athrough-the-scope (TTS) tack-based suture system. Patients and methods This was a two-center retrospective study of RYGB patients who underwent single-stage EDGI using a 20-mm LAMS and subsequent primary anastomosis closure with the X-tack system at the time of stent removal. Patient demographics, procedure details, clinical outcomes, and imaging findings are reported. Results Nineteen patients (median age 63 years, 84% female) underwent single-stage EDGI with a median follow-up of 31.5 months. Adverse events occurred in two patients (11%) who had abdominal pain requiring hospitalization. The median LAMS dwell time was 32 days (range 16-86). All patients (100%) who underwent follow-up studies after LAMS removal had confirmed anastomosis closure (n = 18). Most patients had documented weight loss at the time of LAMS removal and at last follow-up (68%, n = 13). Conclusions Single-stage EDGI is an effective approach to managing RYGB patients with pancreaticobiliary pathology. Thus far, endoscopic TTS tack-based suturing appears to have a high success rate in anastomosis closure after LAMS removal and should be considered as a primary method for preventing chronic fistulae.

Investigation into the state of cure of elastomers through nanoindentation

A novel nanoindentation procedure was developed for measuring the mechanical properties of elastomers as they exhibit surface tackiness. A small dynamic load was superimposed to a larger static deformation after a dwell time for allowing stress relaxation. The outcomes of measurements on a fully crosslinked filled acrylonitrile butadiene rubber (NBR) were analyzed to verify the reliability of this procedure. This method was then employed to investigate the mechanical properties of the same elastomer cured at different temperatures and times by injection molding. As expected, a change from viscoplastic to viscoelastic behavior due to the formation of chemical crosslinks over curing time was found, and mechanical properties plateaus were reached more rapidly at higher manufacturing temperatures. The results were then compared with compression set data: similar trends were detected for the loss factor and the compression set, both decreasing down to a plateau level. Overall, the proposed method demonstrated the ability to recognize undercured regions in elastomer samples - particularly through the determination of the loss factor (tanδ) - and may represent a new tool for improving quality control for the rubber industry.

The Drosophila Hippo pathway transcription factor Scalloped and its co-factors alter each other's chromatin binding dynamics and transcription invivo.

The Hippo pathway is an important regulator of organ growth and cell fate. The major mechanism by which Hippo is known to control transcription is by dictating the nucleo-cytoplasmic shuttling rate of Yorkie, a transcription co-activator, which promotes transcription with the DNA binding protein Scalloped. The nuclear biophysical behavior of Yorkie and Scalloped, and whether this is regulated by the Hippo pathway, remains unexplored. Using multiple live-imaging modalities on Drosophila tissues, we found that Scalloped interacts with DNA on a broad range of timescales, and enrichment of Scalloped at sites of active transcription is mediated by longer DNA dwell times. Further, Yorkie increased Scalloped's DNA dwell time, whereas the repressors Nervous fingers 1 (Nerfin-1) and Tondu-domain-containing growth inhibitor (Tgi) decreased it. Therefore, the Hippo pathway influences transcription not only by controlling nuclear abundance of Yorkie but also by modifying the DNA binding kinetics of the transcription factor Scalloped.

Asynchronous control of networked periodic piecewise linear systems under time-varying transmission delay

This paper studies the stability of networked periodic piecewise linear systems (NPPLSs) of which communication channels are subject to a time-varying transmission delay. Under data-sampling, the NPPLS is modeled as an asynchronous controlled periodic piecewise linear system with time-varying input delay, where the interval of asynchronous control in each subsystem is uncertain but bounded. Aimed at obtaining less conservative stability and synthesis results when tackling the uncertain switching, the dwell time of each subsystem is divided into three subintervals according to the asynchronous control interval and the maximum delay assumption. In this way, it allows the construction of piecewise Lyapunov functionals for one subsystem, the piecewise Lyapunov functionals capture different dynamic characteristics in each subinterval. Using this approach, general stability conditions of NPPLSs are derived. Then, by constructing Lyapunov functionals as a set of delay-dependent time-varying functionals, tractable exponential stability conditions of NPPLSs under transmission delay are developed using a scaling technique. Due to the coupling of the decision variables in the conditions, an iterative algorithm is proposed to solve the periodic controller gains. A numerical example is provided to illustrate the merits of the obtained controllers.

2D and 3D characterization of oxidation‐fatigue mechanisms in an advanced Ni‐based superalloy: Effects of microstructure and elevated temperature

AbstractThe effects of varying γ′ size and grain boundary carbide distribution at elevated temperatures on the fatigue behavior of turbine disk alloy RR1000 were examined through combining 2D and 3D imaging characterization. The fatigue crack growth rate at 725°C is higher than at 650°C due to enhanced oxidation damage at higher temperature, dominated by an intergranular fracture mode. This is more marked with longer dwell time (linked to diffusion time) and when carbides have formed continuously at grain boundaries. The fatigue crack path was characterized by X‐ray CT scan to present the complex 3D crack propagation morphology. It is noted that a discontinuous crack path and uncracked ligaments can be discerned ahead of the crack tip particularly in the microstructure where carbides are continuously formed at grain boundaries. This is linked to embrittled zones ahead of the crack tip formed during longer dwell times at the maximum stress during cycling at elevated temperature.

Improving bonding strength of medium-thick Al-Cu dissimilar joint by a novel splat cooling assisted double side friction stir welding

To obtain a high-strength medium-thick Al-Cu dissimilar joint, a novel splat cooling assisted double side friction stir welding (SDS-FSW) is proposed. The microstructure and tensile properties of conventional double-side friction stir welding (DS-FSW) and the novel SDS-FSW joints under optimal welding parameters are systematically compared, it shows that the utilization of in-process splat cooling significantly reduces the welding peak temperature and the high-temperature dwell time. The in-process splat cooling causes significant grain refinement in the welding nugget zone (WNZ) of the Al-Cu dissimilar SDS-FSWed joint, it exists the lower recrystallization fraction and the higher KAM value. Although both DS-FSW and SDS-FSW joints fracture at the Al-Cu interface, the DS-FSW joint represents a brittle fracture characteristic, while the SDS-FSW joint represents a mixed ductile-brittle fracture mode. Under the drive of the mechanical stirring of the tool and the welding thermal cycle, the aluminium atoms and copper atoms diffuse to the copper base material and aluminium base material, respectively. Since copper diffuses in aluminium at a higher diffusion rate than aluminium diffuses in copper, and the solubility of copper in aluminium is much smaller than that of aluminium in copper, thus the Al2Cu becomes the first phase with the nucleation and growth. As the welding temperature and time continue to increase, Al2Cu reaches the supersaturation state, and the Al4Cu9 phase is produced between the Cu (Al) and the Al2Cu phase. In the end, the interface forms the stable double-layer IMCs structure (Al2Cu/Al4Cu9). The optimal tensile strength of the SDS-FSWed joint is 159 MPa, which is increased by 42% compared to the DS-FSWed joint at the same welding parameter. This was mainly because in-process splat cooling contributed to forming a thinner IMCs layer at the A-Al-Cu interface. It reveals that the application of in-process splat cooling is a versatile method to thin the IMCs layer at the Al-Cu medium-thick DS-FSW process.

Multimode fiber-coupled VIPA spectrometer for high-throughput Brillouin imaging of biological samples

Slow acquisition time and instrument stability are the two major limitations for the application of confocal Brillouin microscopy to biological materials. Although overlooked, coupling the microscope to the spectrometer with a multimode fiber (MMF) is a simple yet viable solution to increase both the detection efficiency and the stability of the classical single-mode fiber-coupled virtually imaged phase array (VIPA) instruments. Here we implement the first successful MMF-coupled VIPA spectrometer for confocal Brillouin applications and present a dimensioning strategy to optimize its collected power. The use of an MMF brings a tremendous improvement on the stability of the spectrometer that allows performing experiments over several weeks without realignment of the device. For instance, we map the Brillouin shift and linewidth in growing ductal and acinar organoids with a spatial resolution of 1×1×6μm3 and 50ms dwell time. Our results clearly reveal the formation of a lumen in these organoids. Careful examination of the data also suggests an increase in the viscosity of the cells of the assembly.

Asynchronous control of switched systems with time-delay based on mode-dependent average dwell time

Switched system is a kind of important hybrid system, which is usually composed of finite subsystems and an organization switching rule. In the study of switched system, it is usually default that the subsystem and the sub-controller are switched synchronously. However, in practice, the switching of sub-controller often lags behind the subsystem, resulting in asynchronous switching between subsystem and sub-controller, which affects the stability of the system. To solve this problem, this paper discusses the asynchronous control problem of a class of time-varying delay switched systems based on mode-dependent average dwell time (MDADT). Firstly, by constructing a dynamic output feedback controller and using piecewise Lyapunov function, the sufficient conditions for exponential stability and H∞ performance of the closed-loop switching system are obtained. At the same time, the design algorithm of dynamic output feedback controller is given. Finally, a simulation of a switched system with two subsystems under ADT switching signal and MDADT switching signal is given, and the effectiveness of the proposed method is verified by comparison.

Does Reduced Dwelling Time Leads To Higher Tax Revenue? The Important Role Of Government Effectiveness In ASEAN-5

This study aims to analyze the factors that affect tax revenue on international trade in ASEAN-5 countries. Data was obtained from The World Bank and analyzed using panel data regression. Variables used in this study are tax revenue on international trade, import growth, dwelling time, and government effectiveness. The results show that import growth, dwelling time, import growth that has been moderated by government effectiveness, and dwelling time that has been moderated by government effectiveness simultaneously affect tax revenue on international trade. Partially, import growth, dwelling time, and government effectiveness have a positive effect on tax revenue on international trade. However, when moderated by government effectiveness, import growth and dwelling time show a negative effect on tax revenue on international trade. The recommendation from this study is for the government to improve the quality of public services in the process of loading and unloading goods. Effective public services at ports and airports, balanced with efforts to reduce dwelling time, will increase tax revenue on international trade. The steps that the government can take are to simplify business processes at the port, for example, joint inspection between customs and quarantine authorities. In addition, the government needs to sterilize port and airport areas so that unauthorized parties do not hinder the flow of goods in and out. Public service improvements can also be made in other sectors because they have a significant impact on increasing tax revenue on international trades.

Finite-time bumpless transfer control problem for switched LPV systems with guaranteed switching frequency

For the switched linear parameter-varying (LPV) systems, the finite-time bumpless transfer control (FTBTC) issue is addressed by utilising the parameter-dependent multiple piecewise Lyapunov function method. First, for the switched LPV systems, a finite-time bumpless transfer performance is proposed, which only demands that bumpless transfer inequation holds in the activated interval in place of entire intervals. Second, a switching law depending on external parameters, system state, dwell time is designed to guarantee switching frequency. Third, a time-varying switching controller is designed, under which a solvable condition of the FTBTC issue is presented. It allows the FTBTC issue of each subsystem to be unsolvable. Finally, an aero-engine model is established to confirm the availability of the proposed scheme.

A Novel Viscoelastic Deformation Mechanism Uncovered during Vickers Hardness Study of Bone.

This study investigates the viscoelastic deformation mechanisms of bone as a response to Vickers hardness indentation. We utilized advanced high-resolution scanning electron microscopy (SEM) to investigate a distinct deformation pattern that originates from the indentation site within the bone matrix. The focus of our research was to analyze a unique deformation mechanism observed in bone tissue, which has been colloquially termed as "screw-like" due to its resemblance to a screw thread when viewed under an optical microscope. The primary goals of this research are to investigate the distinctive characteristics of the "screw-like" deformation pattern and to determine how the microstructure of bone influences the initiation and control of this mechanism. These patterns, emerging during the dwell period of indentation, underscore the viscoelastic nature of bone, indicating its propensity for energy dissipation and microstructural reconfiguration under load. This study uncovered a direct correlation between the length of the "screw-like" deformation and the duration of the indentation dwell time, providing quantifiable evidence of the bone's viscoelastic behavior. This finding is pivotal in understanding the mechanical properties of bone, including its fracture toughness, as it relates to the complex interplay of factors such as energy dissipation, microstructural reinforcement, and stress distribution. Furthermore, this study discusses the implications of viscoelastic properties on the bone's ability to resist mechanical challenges, underscoring the significance of viscoelasticity in bone research.