Breakdown Effects Research Articles

Adult intergenerational proximity and parents’ depressive symptoms: A bidirectional approach

To date, only a few studies have investigated the bidirectional relationship in the intergenerational proximity-health nexus, specifically how geographic proximity affects older parents' depressive symptoms and vice versa. Drawing on eight waves (2004–2018) of the U.S. Health and Retirement Study (n = 17,671), we examine several mechanisms (‘mobilization’, ‘social support’, and ‘social breakdown’) that drive the complex relationship between intergenerational proximity and parental depressive symptoms. Dynamic panel models with fixed effects in a structural equation modeling context provided some weak evidence of a ‘mobilization effect’ (that is, parents', especially fathers', depression triggering greater proximity, including coresidence) and somewhat clearer evidence for a ‘social breakdown effect’ of coresidential transitions on parents' depressive symptoms (particularly among ‘Whites’ and fathers). We found no evidence to support the notion of a ‘social support mechanism’ (predicting that greater proximity or the transition to coresidence would decrease the number of parents' depressive symptoms).

Enhancing CAR-T cell therapy against solid tumor by drug-free triboelectric immunotherapy

Chimeric antigen receptor (CAR) T cell therapy is a highly effective immunotherapy for hematological tumors, but its efficacy against most solid tumors remains challenging. Herein, a novel synergistic combination therapy of drug-free triboelectric immunotherapy and CAR-T cell therapy against solid tumor was proposed. A triboelectric nanogenerator (TENG) that can generate pulsed direct-current by coupling triboelectrification effect and electrostatic breakdown effect was fabricated. The TENG can generate up to 30 pulse direct-current peaks with peak current output ≈35 μA in a single sliding to power the triboelectric immunotherapy. The pulsed direct-current stimulation induced immunogenic cell death of tumor cells (survival rate of 35.9 %), which promoted dendritic cells maturation, accelerated the process of antigen presentation to CAR-T cells and enhanced the systemic adaptive immune response. Furthermore, triboelectric immunotherapy promoted M1-like macrophage polarization, reduced regulatory T cells differentiation and reprogrammed the tumor immunosuppressive microenvironment, which ultimately enhanced the efficacy of CAR-T cells to eradicate nearly 60 % of NALM6 solid tumor mass. Notably, considering that triboelectric immunotherapy is a safe and effective drug-free antitumor strategy, the combined therapy did not increase the burden of double-medication on patients.

Miniaturization of high beam quality 1.543 μm Raman laser with backward stimulated Raman scattering

It is very challenging to make high peak power (big pulse energy) Raman lasers compact, due to laser induce breakdown (LIB) effect; and it is even more difficult to achieve a decent beam quality meanwhile. In this work, a pulsed 1064 nm laser was used as pump source; pressurized methane was used as Raman active medium, which had the largest ratio of backward/forward Raman gain coefficient among all gaseous media; and backward first Stokes (BS1) Raman laser of 1543 nm with good beam quality was realized. When an f=0.5 m lens was used to focus pump beam into a 0.9 m long Raman cell filled with 3.5 MPa methane, 276.1 mJ BS1 was achieved, the corresponding photon conversion efficiency was 70.8% and the peak power was 83.7 MW. BS1 beam quality was measured to be Mx2=2.54,My2=2.28, which was significantly better than that of pump laser. In a setup of f=0.3 m focal lens and 0.5 m long Raman cell, 197.8 mJ BS1 was achieved, with the company of serious LIB. In order to meliorate LIB and improve BS1 conversion efficiency, the focal lens was tilted by 20°, pump laser beam waist and depth of focus increased significantly, BS1 was improved to 225.0 mJ, the corresponding photon conversion efficiency was 58.5%. An even short focal lens and Raman cell with reasonable BS1 energy was possibly achieved by tilting a shorter focal lens by a larger angle. This work also demonstrated that the increment of BS1 conversion may help to reduce the effect of LIB on SRS process.

INCREASING THE STABILITY OF ORGANISATIONAL AND TECHNICAL SYSTEMS THROUGH THE USE OF MACHINE LEARNING

The stability of technical and organisational-technical systems is an integral factor in the functioning of a wide range of complex technical and organisational-technical systems, such as energy systems, industrial facilities, transport systems, and others. While it depends on various factors, there are currently no means to support decision-making for automated dispatch control systems users in case of failures. The article analyses the effects of failures and breakdowns in complex technical and organisational-technical systems. It provides examples of major technogenic disasters. The study examines the human factor influence on the emergence of technogenic disasters. Currently, automated dispatch control systems do not have any means to facilitate decision-making by providing the dispatcher with a clear plan of action to troubleshoot and eliminate a possible disaster. The authors propose a concept of support means for decision-making in response to crises using automated dispatch systems for managing complex organisational-technical systems based on machine learning and artificial intelligence. The means is based on machine learning methods and has a two-component structure: an artificial neural network that defines the type of failure and a programme component that selects the algorithm. The neural network is implemented in the Python programming language, and the user interface is in the C# language. The neural network fulfils the classification task defining the failure based on an array of logical variables that demonstrate the change of state of system elements. The programme component uses the database created with SQL language to define the algorithm of actions for the dispatcher. The authors describe the dataset for the model in case of its use in energy systems. There is also a description of the model components. The model’s distinguishing features are adaptivity due to machine learning methods and the possibility of further model training to increase the classification accuracy based on its use cases. Keywords: machine learning, automated dispatch control systems, decision-making support, system stability.

Breakdown of the molecular orbital picture for X-ray emission of water

By measuring X-ray emission of the water molecule in liquid phase we establish a first example of K-shell X-ray emission spectra with strong breakdown of the molecular orbital picture. A complete splitting of the 2a1 peak into satellites is observed. A theoretical model with electronic configurations generated by coupled excitations/de-excitations, so-called semi-internal configuration interaction, captures the experimentally recorded features well. Differences with respect to the corresponding breakdown effect in ultraviolet photoelectron spectrum are highlighted. Molecular dynamics calculations indicate that solvent broadening can only make up for a small fraction of the width of the recorded 2a1 derived band.

Round Splashes of a Viscous Liquid

The splashes of a highly viscous fluid (glycerol) resulting from its pulsed displacement from a gap between two rapidly approaching disks are studied. It is found that, outside the disks, the splash has the form of a thin film bounded by an annular rim. A physical model of the splash is formulated, and analytical solutions describing its trajectory are given. The calculation results are compared with experimental data. The effects of fluid viscosity, surface tension, and film breakdown are analyzed. It is shown that the key influence on the splash development scenarios is exerted by surface tension of the film connecting the rim to the disks.

Mathematical Analysis for GPU Framework for High Performance Computing with Improved Scalability, Reliability and Seamless Configurability

In the field of High Performance Computing (HPC), which is changing very quickly, using Graphics Processing Units (GPUs) has become essential for getting a lot of computing power and speed. This study gives a thorough mathematical analysis of a GPU system that is meant to improve scalability, stability, and configurability, all of which are very important for next-generation HPC apps. The suggested framework uses complex mathematical models and methods to make the best use of GPU resources, cut down on delay, and guarantee strong performance across a wide range of tasks. Scalable parallel processing methods are built into the framework so it can adapt to changing computing needs, making the most of speed and resource use. Fault-tolerant methods that lessen the effects of hardware breakdowns and computing mistakes also improve reliability, making sure that results are always correct and consistent. The framework can be set up in different ways because it is based on flexible design, which makes it easy to change and adapt to the needs of each application without affecting speed. In diverse computer settings, where different apps may have different working needs, this ability to change is very important. The mathematical analysis includes performance measures like speed, delay, and mistake rates, which give a solid basis for judging how well the system works. Additionally, tests comparing the suggested system to current GPU tools show that it is more reliable and scalable. This study helps make better, more reliable computer systems by looking at some of the biggest problems in GPU-based high-performance computing. The results show that using this method can greatly improve the skills of HPC systems, which can lead to progress in scientific study, data analysis, and complex models. In the end, this work shows how advanced GPU systems can help drive innovation in HPC, leading to more powerful, reliable, and flexible computing options.

Resting time effects on flow properties of cementitious materials: a study on self-compacting concrete equivalent mortar made with recycled aggregates

The concrete equivalent mortar (CEM) method, mainly used in the laboratory, offers a course that facilitates and accelerates experimental test programs with relatively small amounts of materials. To this end, two CEM mixes, with natural and recycled aggregates, at different superplasticizer (SP) concentrations, were tested. The key objective was to investigate how CEM flow property changed at 0, 30, and 60 min of resting time, emphasizing the material’s structuring and destructuring effects. This study describes the flow behaviour of CEMs applying specific tools. Also, a vane-geometry rheometer was used to obtain rheological flow curves. Whatever the SP content in the structuring state, the results indicated reduced flow properties over time. However, an SP content of 1.3% retard the structural build-up property that was not evident at 60 min-rest time. Spread diameters ranging between 300 and 400 mm are measured with the mini cone immediately after mixing. After 60 min of resting time, these diameters were reduced between 260 and 300 mm. Remixing after prolonged rest periods reduces the flow stress values, which decrease from 10 to 18 Pa to 6 to 14 Pa. After a structural build-up at a rest time, the structural break-down effect by remixing re-fluidifies the mixtures. The fluidity has recovered its initial state, reflecting a thixotropic property.

Effects of nanomagnesia and polypropylene-graft-maleic anhydride on the dielectric breakdown properties of polypropylene/ethylene propylene diene monomer blend

Thermoplastic polypropylene (PP) has garnered a significant attention in power cable insulation research because of its exceptional thermal tolerance and dielectric properties. Due to its poor impact strength at room temperature, PP has been blended with various elastomers, including ethylene-propylene-diene monomer (EPDM), to improve the mechanical stiffness of the final material. This, however, comes with compromised dielectric properties of the material. Recently, the addition of nanofillers to polymers has demonstrated promising properties that can be tailored for various dielectric applications, provided that nanofiller and polymer interactions are appropriately formulated. Nevertheless, the effect of nanostructuration in PP/elastomer blends, especially from the perspective of dielectrics, have yet to be systematically explored. In the current work, magnesia (MgO) nanofiller is added to a model PP/EPDM blend system to determine the effect of MgO on the breakdown properties of PP/EPDM. The results show that adding 0.5 wt% of MgO to PP/EPDM reduces the AC and DC breakdown strengths by 7% and 16%, respectively. As the amount of MgO increases to 3 wt%, the AC and DC breakdown strength reduces further by 25% and 29%, respectively. Significantly, appropriate modification of the nanocomposites with polypropylene-graft-maleic anhydride (PP-g-MAH) can result in 5% higher breakdown strength of the nanocomposites with respect to comparable nanocomposites without modification. The mechanisms surrounding these breakdown effects are discussed with the aid of materials structure interpretations. Overall, the results demonstrate that appropriate modification of nanocomposites with PP-g-MAH is crucial in tailoring breakdown properties of PP blend nanocomposites.

A polysilicon based bipolar-like avalanche light-emitting diode with an enhanced avalanche breakdown effect

The advantage of silicon-based avalanche N + P junction LEDs is that they are compatible with silicon CMOS processes and facilitate optoelectronic integration, but their relatively high operating voltage limits their applications. In view of this, we propose a polysilicon avalanche LED (light-emitting device) with a bipolar-like structure that has a different avalanche breakdown mechanism from that of a normal PN junction, achieving an operating voltage significantly lower than that of a conventional N + P LED. Five polysilicon avalanche LEDs with base lengths ranging from 4 µm to 10 µm have been fabricated and tested. They have proven to operate at voltages as low as about 6–7 V, while the conventional N + P LEDs used for comparison cannot operate below 9 V. We also observed that they have higher luminous efficiency than the conventional N + P LED. The luminous intensity of the bipolar-like LED with a base length of 4 μm is about 41 % higher than that of the conventional N + P LED at a power consumption of 0.4 W. This demonstrates the advantages of bipolar avalanche LEDs in all-silicon monolithic optoelectronic integration applications.

Dynamic propagation velocity of a positive streamer in a 3 m air gap under lightning impulse voltage

Streamers represent an important stage in the initiation of gap discharge. In this work, we used an eight-frame intensified charge-coupled device camera to capture the streamer development process when a lightning impulse voltage of 95%–100% U 50% was applied in a 3 m rod–plate gap and the streamer velocity was analyzed. Analysis of the observations shows that streamer velocity can be defined by three stages: rapid velocity decline (stage 1), rapid velocity rise (stage 2) and slow velocity decline (stage 3). The effects of electrode shape, applied voltage and gap breakdown or withstanding on streamer velocity were analyzed. The electrode with a larger radius of curvature will result in a higher initial velocity, and a higher voltage amplitude will cause the streamer to propagate faster at stage 3. Gap withstanding or breakdown has no obvious effect on streamer velocity. In addition, the experimental results are compared with previous results and the statistical characteristics of the primary streamer discharge are discussed.

An ultra-high voltage (>10 kV) direct-current triboelectric nanogenerator realized by structural and material optimizations

High-voltage power supplies are pivotal in sectors such as agriculture, medicine, and environmental protection. However, conventional high-voltage sources are associated with environmental pollution, cumbersome size, high costs, and significant safety risks due to the accompanying high current. To address these challenges, we propose a high-voltage source that employs a direct-current triboelectric nanogenerator (DC-TENG). Based on contact electrification and electrostatic breakdown effects, the inherent electrostatic charges and minimal fixed capacitance enable the DC-TENG to generate ultra-high voltage with low current effortlessly. To fully harness the potential of this high-voltage technology, a theoretical model encompassing multiple discharge domains is developed and the three main constraints on open-circuit voltage are identified. Guided by the model, the optimized DC-TENG achieves a record output voltage of 10.85 kV through structural and material optimizations, effectively achieving water-oil separation and air purification within 2.5 and 3 minutes, respectively. This research not only fully exploits the high-voltage capabilities of DC-TENG but also offers an eco-friendly, portable, cost-effective, and safe alternative for supplying ultra-high voltage.

Mesoscale model for computational simulation of reaction driven by dielectric breakdown in metal-polymer propellants

The reactivity of heterogeneous energetic materials (HEMs) intimately depends on the underlying microstructural effects. For reactive materials, key factors include the microstructure distribution, morphology, size scale of heterogeneities, reactant mixing, and chemical kinetics of the reactants. We report the development of a mesoscale model for simulating the evolutions of the hotspot field and associated reaction processes when such materials are exposed to external excitations. The model explicitly accounts for microstructure, interdiffusion between the reactant species, advection of the species mixture, and chemical kinetics of the reaction. An Arrhenius relation is used to capture the rate of reactive heat release. The particular material analyzed is a composite of poly(vinylidene fluoride-co-trifluoroethylene) and nanoaluminum [or P(VDF-TrFE)/nAl]. The excitation leading to the initial microstructural temperature increase that kicks off the exothermic reactive processes is the dissipative heating arising from dielectric breakdown under the electric field developed through piezoelectricity and flexoelectricity of P(VDF-TrFE). As such, the model resolves both the breakdown process and the diffusion, advection, and exothermic reaction processes. The evolutions of the temperature and species distribution fields under the combined effects of breakdown and chemistry are used to predict the effects of microstructure, diffusion, and kinetics on several key metrics characterizing the reactive responses of the material. This mesoscale framework admits the quantification of uncertainties in these predicted macroscopic behavior measures due to microstructure heterogeneity fluctuations through the use of multiple, random but statistically equivalent microstructure instantiations. Although the particular hotspot inducing mechanism considered is dielectric breakdown here, the framework can be adapted to analyze reaction initiation and propagation and establish microstructure–reaction behavior relations under other types of hotspot inducing mechanisms, such as thermomechanical inelastic dissipation, frictional heating, and laser or microwave excitation.

A High-Voltage-Specialized Direct-Current Triboelectric Nanogenerator for Air Purification.

Human health and the environment face significant challenges of air pollution, which is predominantly caused by PM2.5 or PM10 particles. Existing control methods often require elevated energy consumption or bulky high-voltage electrical equipment. To overcome these limitations, a self-powered, convenient, and compact direct current high-voltage triboelectric nanogenerator based on triboelectrification and electrostatic breakdown effects is proposed. By optimizing the structure-design of the direct current triboelectric nanogenerator and corresponding output voltage, it can easily achieve an output voltage of over 3kV with a high charge density of 320 µC m-2. A power management circuit is designed to overcome the influence of third domain self-breakdown, optimize 92.5% amplitude of voltage shake, and raise 5% charge utilization ratio. With a device size as tiny as 2.25 cm3, it can continuously drive carbon nanowires to generate negative ions that settle dust within 300 s. This compact, simple, efficient, and safe high-voltage direct current triboelectric nanogenerator represents a promising sustainable solution. It offers efficient dust mitigation, fostering cleaner environments, and enhancing overall health.

Modulation of electrodes on the sensitivity of the Pockels effect

In order to improve the sensitivity of the system in the Pockels effect, a design scheme for adding antennas at both ends of the crystal is proposed. Firstly, the influence of the applied electric field on the refractive index of the crystal is explored, and the relationship between the applied electric field and the output of the system is deduced. Secondly, two different antenna models are designed (one is to connect the antenna directly to both ends of the crystal, and the other is to connect the antenna after coating on the crystal), the distribution of the applied electric field in the internal field of the crystal under different models is studied, and the corresponding input and output transfer functions are analyzed. The analysis shows that the sensitivity of the system is improved in different antenna modes, and the crystal coating has little effect on the sensitivity. In addition, the antenna model without coating is simple to install, but the internal field strength of the crystal shows a tendency to be large in the middle and small at both ends, so it is easier to produce electric field breakdown effect in the strong field. The internal field strength distribution of the coated crystal is approximately uniform field, and the field strength maximum is smaller than that of the non-coated antenna model, so crystal breakdown is not easy to occur in the strong field. Finally, the effectiveness of the theoretical analysis is verified by experiments.

High-performance pneumatic solid–liquid triboelectric nanogenerator

In the field of blue energy harvesting, solid-liquid triboelectric nanogenerators (SL-TENG) show significant potential. However, their low output performance in energy applications is limited due to the relatively small contact area and slow separation speed during the friction process. To overcome these limitations, we develop a pneumatic solid-liquid triboelectric nanogenerator (PSL-TENG) with ultrahigh output performance based on pneumatic solid-liquid triboelectrification and electrostatic breakdown. The pneumatic design effectively increases the solid-liquid interface area and the solid-liquid contact and separation rate, which can enhance solid-liquid triboelectrification effect. The synergistic design of the horn and the bent pipe can converge positively charged mist into large droplets, which can enhance electrostatic breakdown effect. This innovative design approach has achieved outstanding output performance, with a peak instantaneous voltage of 6436 V and a peak instantaneous current of 3.05 mA. This exceptional output performance is sufficient to directly power 3000 LED lights or a 55 W commercial lamp. These research achievements provide new insights for SL-TENG in energy harvesting, as significant output can be generated by collecting the inherent charges of liquids themselves.

Quantifying Dielectric Material Charge Trapping and De-Trapping Ability Via Ultra-Fast Charge Self-Injection Technique.

Recently, utilizing the air breakdown effect in the charge excitation strategy proves as an efficient charge injection technique to increase the surface charge density of dielectric polymers for triboelectric nanogenerators (TENGs). However, quantitative characterization of the ability of dielectric polymers to trap reverse charges and the effect on the startup time of secondary self-charge excitation (SSCE) are essential for extensive applications. Here, an ultra-fast charge self-injection technique based on a self-charge excitation strategy is proposed, and a standard method to quantify the charge trapping and de-trapping abilities of 23 traditional tribo-materials is introduced. Further, the relationship among the distribution of dielectric intrinsic deep, shallow trap states, and transportation of trapped charges is systematically analyzed in this article. It shows that the de-trapping rate of charges directly determines the reactivation and failure of SSCE. Last, independent of TENG contact efficiency, an ultra-high charge density of 2.67 mC m-2 and an ultra-fast startup time of SSCE are obtained using a 15µm poly(vinylidene fluoride-trifluoroethylene) film, breaking the historical record for material modification. As a standard for material selection, this work quantifies the charge trapping and de-trapping ability of the triboelectric dielectric series and provides insights for understanding the charge transport in dielectrics.

Memory effect and statistical characterization of pulsed vacuum microdischarge breakdowns between palladium electrodes from 500 nm up to [formula omitted

The understanding of microgaps breakdown phenomena at controlled laboratory conditions represents an important prerequisite in the development of future micro-plasma technologies. The present work is focused on the observation of the electrical discharge parameters of the pulsed vacuum breakdown between palladium electrodes. The quasi-homogeneity of the generated fields was achieved using a plane-to-sphere geometry of the electrodes separated from 0.5 to 10μm. The first part of the study covers the conditioning process of the electrodes, including a comparison of the pair-virgin and single-virgin electrode configurations. A detailed statistical analysis of the discharge parameters, such as the breakdown voltage, the duration and the energy released during a pulse, and minimal power for maintaining the discharge is provided for different gap configurations for a voltage ramp speed of 107 kV/s. The analysis with respect to breakdown voltage yielded the observation of the memory effect between subsequent breakdowns.

Trace Cu (II) removal from N-methylpyrrolidone with hydrogel rich in O, N and S active sites

The presence of a considerable quantity of metal ions in N-methylpyrrolidone (NMP) applied for the cleaning of electronic devices, especially chips, results in a breakdown effect, thus affecting their overall durability and performance. Here, hydrogel that rich in O, N, and S active sites was prepared, which can effectively remove trace amounts of Cu (II) from N-methylpyrrolidone. The material was synthesized through a one-pot crosslinking and ion exchange method and is named SLH. The physicochemical properties and adsorption experiments were conducted. It was found that SLH-2 exhibited outstanding Langmuir maximum adsorption capacity of 136.99 mg/g at an initial Cu (II) concentration of 200 mg/L. By utilizing SLH-2 in electronic grade adsorption experiments, concentration of trace Cu (II) decreased from 12.3 μg/L to 5.39 μg/L. Additionally, concentration of Zn, Fe, Mg, and Ni significantly reduced to less than 1 μg/L, with –NH2 and –COOH playing crucial roles in the adsorption process. The research results indicate that predominant adsorption mechanisms are surface coordination and ion exchange. The adsorption energy between active functional groups and Cu (II) was calculated using density functional theory (DFT), revealing an affinity order of –COOH > –SO3H > –NH2 > –OH. This work not only developed an adsorbent for capturing trace Cu (II), but also provided new strategies for the removal of metal ions in wet chemicals.

When Democracy Brings Insecurity: The Political Legacies of Regime Change

abstract: The circumstances under which a country democratizes can have long-lasting consequences for citizens' political attitudes. To develop this argument, the author links East Germans' satisfaction with the functioning of democracy today to their experiences during German reunification: East Germany democratized under conditions of extreme economic uncertainty, which has had enduring effects on how economic evaluations are linked to democracy satisfaction. An original survey experiment finds that qualitatively similar experiences of current economic insecurity have stronger effects on East than West Germans' democracy satisfaction. Household panel data show that this effect is stronger among those East Germans who experienced more economic hardship during the transition. Surveys of East Germans prior to reunification demonstrate that a similar pattern did not exist before the transition. Finally, cross-national survey data document similar patterns among Eastern Europeans more broadly. These findings complement existing work on the legacies of authoritarian rule by emphasizing the lasting attitudinal effects of authoritarian breakdown.