Internal Trap Research Articles

Artificial nociceptor based on interface engineered ferroelectric volatile memristor

Recent advancements in neuromorphic computing driven by memristors, which emulate biological synapses and neurons, have spurred the development of innovative information technologies. To extend memristor applications to artificial nervous systems, electronic receptors are crucial for converting external stimuli into signals for the internal nervous system. Key requirements for integrating neuron devices into neuromorphic computing include achieving threshold behavior, minimizing power consumption, and ensuring compatibility with complementary metal-oxide semiconductor (CMOS) technology. Hafnium-based ferroelectric memristors are known for their robust ferroelectric properties at nanoscales and compatibility with CMOS technology. However, their non-volatile resistive switching has historically limited their suitability for neuron sensory applications requiring threshold switching. This study demonstrates threshold switching behavior in a TiN/Hf0.67Zr0.33O2(HZO)/TiOx/TiN heterostructure by incorporating a nanoscale TiOx interfacial layer as an oxygen reservoir. This layer facilitates the formation of oxygen vacancies within the ferroelectric HZO layer, serving as internal charge trap sites. As a result, hafnium-based ferroelectric memristors exhibit volatile switching characteristics, enabling them to function as nociceptive devices through internal charge trapping and detrapping mechanisms. These volatile memristors are suitable for artificial nociceptor systems requiring responses such as threshold detection, relaxation, allodynia, and hyperalgesia to external stimuli. This capability opens avenues for developing advanced humanoid robots capable of rapid adaptation and response in challenging environments such as outer space or hazardous conditions, leveraging real-time sensory processing for effective operation and survival.

Effect of pitfall trap design on internal trap temperature and the implications for live-trapped lizards

Effect of pitfall trap design on internal trap temperature and the implications for live-trapped lizards

Vertical SiC Photoconductive Switch With Axial Optical Internal Reflection Trap

The SiC vertical photoconductive switch with an axial optical internal reflection trap to improve the ON-state performance is presented. The extrinsic light absorption of vanadium (V)-doped SiC photoconductive switch is low. As such an axial optical reflection trap is used to increase the optical path and total optical absorption. The trap consists of a convex lens, a silver mirror electrode with a hole, and a transparent electrode to create a quasi-total internal reflection structure. Simulation and experimental evaluation reveal that both the device’s light absorption and output current have been improved significantly. Compared with regular axial illumination without the reflective trapping arrangement, the structure fabricated on a V-doped 4H-SiC device demonstrates a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.5\times $ </tex-math></inline-formula> improvement in photoelectric conversion responsivity.

Bi-activated MgGa2O4 phosphors with rich defect energy levels: Spectral property and optical storage applications

Optical high-density information storage can meet explosive increase in significant data demand. Electron-capture materials are very promising for optical information storage. The trap density and depth of the material limit their storage density and information retention. This work successfully prepared a novel material with abundant trap energy levels by selective Bi3+ doping into the MgGa2O4 host (MgGa2O4:Bi3+). A combinatorial synthesizer screened the optimal Bi doping ratio. The optical storage mechanism was systematically analyzed based on the energy band structure combined with theoretical calculations. The internal trap properties of MgGa2O4:Bi3+ were studied in detail using photoluminescence spectroscopy, X-ray photoelectron spectroscopy, electron spin resonance, etc. Ascribed to the high density of defects with Bi doping, the existence of multiple continuously distributed trap levels in MgGa2O4:Bi3+ could be verified, where deep traps are essential for information storage. Not only the capability of optical storage was characterized by the visualization method, and the {10 × 10} information points were encoded/decoded by femtosecond laser on the surface of the simulated disk. The information conversion between binary 0 and 1 was successfully achieved, making it an excellent optical storage medium for the future.

Study on Space Charge Characteristics of Transformer Insulating Paper Under Different Working Conditions

The space charge effect of transformer insulating paper will distort its internal electric field, and its space charge effect will be more prominent under extremely complex working conditions. At present, the micromechanism of charge transport and electric field distortion characteristics of paperboard are not clear under complex working conditions. So in this article, based on the bipolar carrier transport (BCT) model and the dynamic carrier balance model, the effects of high temperature, aging degree, moisture content, and bent degree on charges accumulation in paperboard are studied under dc high voltage by numerical simulation and the measured data needed for simulation. The results show that the higher temperature strengthens the carrier migration, deepens the injection depth of the charge, and aggravates the distortion of electric field intensity in paperboard. The more extended the aging time of paperboard, the greater the internal trap density and the deeper the trap depth, which lead to charges migration difficultly. Increasing water content in the paperboard will accelerate space charges to reach a steady state, while further increasing it will slow down this process, which is related to the shallow trap getting deeper. When the critical part of paperboard is extruded, many traps are introduced, resulting in charges accumulation seriously. The research results can reference the design of paperboard and the maintenance of transformer insulation system.

A study of photoelectric properties of grown SnSe2 crystal by direct vapour transport technique

The opto-electrical properties of Tin Diselenide (SnSe2) crystal are significant for application in photo detectors, optoelectronic devices and many more. Metal chalcogenide SnSe2 has been grown by direct vapor transport (DVT) technique. The chemical composition of grown crystal was studied by energy dispersive analysis of X-ray (EDAX). The photo detection property of SnSe2 crystal based photo detector was exploited for their envisioned applications in optoelectronics. SnSe2 crystals have observed an outstanding photo response ability at room temperature (300 K) with changing illumination intensities 50, 75, 100 and 125 mw/cm2. Moreover, the related parameters, photoresponsivity (R) spectral detectivity (D), external quantum efficiency (EQE), internal quantum efficiency (IQE) and trap depth parameters have been evaluated for pure SnSe2 crystal.

The Case of the Elusive Oscillating Bullet Embolus and Its Ultimate Jailing

<h3>Introduction and Objective</h3> Intravascular missile embolus is a rare, but potentially morbid, result of penetrating trauma. Herein, we present the case of a 43-year-old man with a single ballistic injury to the left hip, resulting in an isolated injury to the iliac wing, entry into the lumen of the left common iliac vein, and an embolic course to the atriocaval junction. The missile subsequently and repeatedly migrated to a variety of locations in the venous system. The oscillating behavior of the bullet and its ultimate endovascular management demonstrates a novel scenario which may be applicable in the treatment of future patients. <h3>Methods and Case Management</h3> A 43-year-old man, presented to our department trauma center with an isolated gunshot wound to the left hip. Initial plain films of the pelvis and abdomen were obtained revealing the absence of a radiopaque ballistic fragment. A plain film of the chest and contrasted cross-sectional imaging soon after revealed the bullet at the atriocaval junction. There were no observed viscous or solid organ injury. Additional imaging studies, temporally spaced, demonstrated the fragment that was then situated in the right pelvis (Figure 1a, 1b, 1c). The ballistic fragment continued to oscillate from the atriocaval junction to the right pelvis as demonstrated on serial plain films. In a hybrid operating theater with fluoroscopic capability, venogram revealed the bullet to be lodged in the right internal iliac vein (Figure 1c). After unsuccessful attempts at snaring the missile, the decision was made to stent across the ostia of the internal iliac vein and trap the missile in place. Sizing was performed using intravascular ultrasound and an 18 × 40 mm Wallstent was successfully deployed to jail the bullet (Figure 1d,1e). <h3>Results</h3> Completion venography demonstrated good result with the bullet excluded. The patient was discharged home on post-operative day two at follow-up 4 months later, he was found to be asymptomatic and doing well. The bullet remains in the right hemipelvis on subsequent imaging studies. <h3>Conclusion</h3> While the occurrence of bullet emboli has not become common enough to have standardized management, the option to trap intravascular ballistic fragments with an endovascular approach, may be a safe alternative compared to more invasive open intervention.

Strongly luminescent and highly stable core-shell suprastructures from in-situ growth of CsPbBr3 perovskite nanocrystals in multidentate copolymer micelles

Lead halide perovskite nanocrystals (NCs) have shown exceptional optoelectronic characteristics and photovoltaic performance; however, their instability has limited their use in optoelectronic applications. Herein, we introduce a facile and effective in-situ synthesis strategy to prepare stable core-shell colloidal perovskite nanocrystal-polymer micelle composites (abbr. ap-POSS-PMMA-b-PDMAEMA@CsPbBr3) by using amphiphilic copolymer (abbr. ap-POSS-PMMA-b-PDMAEMA) self-assembled “reverse micelle” templates. The amphiphilic block copolymer with hydrophobic (ap-POSS and polymethylmethacrylate, PMMA) and hydrophilic blocks (poly 2-(dimethylamino)ethyl methacrylate, PDMAEMA) can be regulated to self-assemble into “reverse” micelles. The micelle serves as a confined nanoreactor during perovskite crystallization, which passivates the perovskite surface by forming a multidentate capping shell and yields the formation of multi-nanocubes with size between 6 and 8 nm and a photoluminescence quantum yield (PLQY) that surpasses 60%. Benefitting from femtosecond transient absorption (fs TA) and time-resolved photoluminescence (PL) spectroscopy studies, the excited carrier dynamics of the obtained composites substantiate fewer internal band-gap trap states from micelle-induced CsPbBr3 NCs. The films cast from these composites showed enhanced water-resistant properties as compared to bare NCs and previously reported encapsulated NCs. Therefore, the copolymer “reverse” micelle induced in-situ grown NCs provide a potential approach for further engineering the morphology of NC-based composites and open the door to potential scalable and robust optoelectronic applications.

Ultraviolet sensor with fast response characteristics based on an AgNW/ZnO bi-layer

We demonstrate an ultraviolet (UV) sensor with fast response characteristics based on an AgNW/ZnO bi-layer. This UV sensor is a surface acoustic wave (SAW)-based sensor fabricated using a 128°YX black lithium niobate substrate, which is a piezoelectric in nature. This sensor, which is a two-port SAW resonator, was manufactured by fabricating interdigitated electrodes with a wavelength of 16.4 μm and depositing UV sensing layers such as ZnO, Sn/ZnO, and AgNW/ZnO. Among these sensing layers, the frequency response characteristics were found to be improved in the bi-layer structure. In addition, the AgNW/ZnO-based sensor showed a significant improvement in response and recovery times. These results contributed to rapid oxygen adsorption on the ZnO surface due to the large oxygen contact area that can attributed to the AgNW’s 3D mesh structure and the compensation of the internal electron trap center due to the contact of the metal-semiconductor. The proposed sensor with the metal-semiconductor bi-layer structure based on AgNW nanomaterials showed the fastest response characteristics compared to previous SAW UV sensors.

VN/S Nanoclusters Encapsulated with Graphene via Zeta Potential Control: A Pomegranate‐Like Cathode for Lithium‐Sulfur Batteries with Enhanced Rate Performance

AbstractA pomegranate‐like cathode, VN/S@G, is synthesized according to a simple principle of electrostatic attraction through a controllable Zeta potential method, establishing a hierarchical‐structured VN/S nanoclusters encapsuled with graphene nanosheets. Internal VN nanoparticles trap lithium polysulphides (LiPSs) and catalyse them transforming from long‐chain to short‐chain species; whereas the external cladding layers of graphene nanosheets confine the transformations in a nanoscale‐catalysis reactors. VN/S@G cathode exhibits excellent long‐cycling life at 2 C rate during the 2000 cycles, corresponding to 0.038 percent of capacity fade per cycle. According to in‐situ Raman and electrochemical impedance spectroscopies, VN catalyst accelerates chemical transformations of liquid‐state LiPSs to solid‐state Li2S2/Li2S and graphene intensifies Li+ diffusion behaviour. Improvement of electrochemical performance of the VN/S@G cathode depends on a coefficient of physical and chemical interactions between VN catalyst and LiPSs species.

Design of An Optical Tweezers System with Fast Digital Feedback for Studying the Mechanochemistry of Cardiac Myosin

Cardiac myosin powers the contraction of the heart and has load dependent kinetics that enable it to adjust its power output in response to load. Dysfunction of cardiac myosin's mechanochemistry can lead to diseases including heart failure, and therefore, there is an outstanding need to probe how mutations and potential therapeutic compounds affect myosin's mechanochemistry under load. Given that cardiac myosin has fast cycling kinetics, we have developed a fast optical trapping system specifically tailored towards probing the mechanochemistry of cardiac myosin. A field programmable gate array (FPGA) board digitizes force signals, applies tunable digital filtering for feedback clamping, controls trap positions through fast interfaces to direct digital synthesizer (DDS) boards, and oscillates the sample stage. Amplified frequencies from each DDS drive acousto-optic deflectors for steering the trapping laser beams. This FPGA-DDS feedback system can respond to changes in bead position due to myosin binding in <33 microseconds. The synchronously acquired data include internal trap position commands, calculated feedback errors, and sample stage position. To demonstrate the system capabilities, we examined the mechanochemical properties of cardiac myosin using the three-bead-assay developed by the Spudich lab. Using our system, it is possible to clearly resolve the kinetics and mechanics of the cardiac myosin working stroke. We use an improved methodology for binding event identification and synchronization, enabling better resolution of the substeps of the myosin working stroke. We also demonstrate the ability of this system to probe the load dependent kinetics of cardiac myosin using both an isometric force feedback clamp and harmonic force spectroscopy. The speed of the system enables measurement of these parameters at physiologically relevant ATP concentrations despite the short lived binding interactions between actin and myosin.

A Total Internal Reflection Photoconductive Switch

We demonstrate a novel illumination technique for extrinsic photoconductive switches based on the creation of a total internal reflection trap to increase the optical path length. The optimal geometry is a square substrate illuminated from one of the corners along the diagonal, ensuring that the total internal reflection condition is maintained after any reflection off the device lateral sides. The optical absorption uniformity throughout the device bulk was improved by designing the entry window to have a cylindrical shape and by using a square core optical fiber as an illumination source. The concept is experimentally validated on a vanadium-doped silicon carbide device that shows approximately four-fold improvement in responsivity compared to normal illumination.

Hybrid perovskite light emitting diodes under intense electrical excitation

Hybrid perovskite semiconductors represent a promising platform for color-tunable light emitting diodes (LEDs) and lasers; however, the behavior of these materials under the intense electrical excitation required for electrically-pumped lasing remains unexplored. Here, we investigate methylammonium lead iodide-based perovskite LEDs under short pulsed drive at current densities up to 620 A cm−2. At low current density (J < 10 A cm−2), we find that the external quantum efficiency (EQE) depends strongly on the time-averaged history of the pulse train and show that this curiosity is associated with slow ion movement that changes the internal field distribution and trap density in the device. The impact of ions is less pronounced in the high current density regime (J > 10 A cm−2), where EQE roll-off is dominated by a combination of Joule heating and charge imbalance yet shows no evidence of Auger loss, suggesting that operation at kA cm−2 current densities relevant for a laser diode should be within reach.

In situ investigation of neutrals involved in the formation of Titan tholins

The Cassini Mission has greatly improved our understanding of the dynamics and chemical processes occurring in Titan's atmosphere. It has also provided us with more insight into the formation of the aerosols in the upper atmospheric layers.However, the chemical composition and mechanisms leading to their formation were out of reach for the instruments onboard Cassini. In this context, it is deemed necessary to apply and exploit laboratory simulations to better understand the chemical reactivity occurring in the gas phase of Titan-like conditions. In the present work, we report gas phase results obtained from a plasma discharge simulating the chemical processes in Titan's ionosphere. We use the PAMPRE cold dusty plasma experiment with an N2CH4 gaseous mixture under controlled pressure and gas influx. An internal cryogenic trap has been developed to accumulate the gas products during their production and facilitate their detection. The cryogenic trap condenses the gas-phase precursors while they are forming, so that aerosols are no longer observed during the 2 h plasma discharge. We focus mainly on neutral products NH3, HCN, C2H2 and C2H4. The latter are identified and quantified by in situ mass spectrometry and infrared spectroscopy. We present here results from this experiment with mixing ratios of 90–10% and 99–1% N2CH4, covering the range of methane concentrations encountered in Titan's ionosphere. We also detect in situ heavy molecules (C7). In particular, we show the role of ethylene and other volatiles as key solid-phase precursors.

Identification of sink spots in two thermal desorption GC/MS systems for the analysis of polycyclic aromatic hydrocarbons

Thermal desorption (TD) GC/MS has been used for the analysis of polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds. However, thermal desorption recovery of PAHs have not been well studied and the cause of PAH residues in a TD system has not been clearly understood. Our results showed that low volatility of PAHs can lead to their incomplete recovery in a TD system: for the PAHs with low vapour pressures, up to 10% and 3% could be lost in a two-stage (TS) TD system and a short-path (SP) TD system, respectively. Within the TSTD system, the majority of residues were found in the 4-port valve and in the spot where internal trap and the 4-port valve connects. Within the SPTD system, residues were largely confined to the tube needle connecting the sample tube and GC injection port as well as inside the injection port. Since the volatility of PAHs can represent the range typical of semi-volatile organic compounds (SVOCs), our results have a wide implication for the thermal desorption of SVOCs in general.

Changes in Trap Temperature as a Method to Determine Timing of Capture of Small Mammals.

Patterns of animal activity provide important insight into hypotheses in animal behavior, physiological ecology, behavioral ecology, as well as population and community ecology. Understanding patterns of animal activity in field settings is often complicated by the need for expensive equipment and time-intensive methods that limit data collection. Because animals must be active to be detected, the timing of detection (e.g., the timing of capture) may be a useful proxy for estimation of activity time. In this paper, we describe a new method for determining timing of capture for small mammals. In our method, two small temperature loggers are positioned in each trap so that one logger registers the internal temperature of a live-trap at set intervals while the other logger simultaneously records external trap temperature. We illustrate the utility of this technique using field data from live-trapping of deer mice, Peromyscus maniculatus, one of the most ubiquitous, widely distributed small mammals in North America. Traps with animals inside registered consistent increases in internal trap temperature, creating a clear, characteristic temperature deviation between the two data loggers that can determine trap entry time within a very narrow time window (e.g., 10 minutes). We also present pilot data to demonstrate the usefulness of the method for two other small-mammal species. This new method is relatively inexpensive, robust to field conditions, and does not require modification of traps or wiring of new devices. It can be deployed as part of common live-trapping methods, making it possible to assay the timing of capture for a large number of animals in many different ecological contexts. In addition to quantifying timing of capture, this approach may also collect meaningful temperature data and provide insight into the thermal costs of animal activity and relationships between environmental conditions and the time of an animal’s capture.

Effects of High Temperatures and Sun Exposure on Sherman Trap Internal Temperatures

Trapping during summer months can expose small mammals to high temperatures inside traps. We measured trap temperatures under different ambient conditions and levels of sun exposure. Internal temperatures of Sherman traps exposed to full sun were 14% higher than those exposed to full sun and fitted with a corrugated cardboard cover and tent. Traps with the surrounding cardboard cover and tent experienced up to a 7.6 °C reduction in internal temperature and could be left out one to two hours longer on average than traps exposed to full sun before internal trap temperatures rose into the minimum lethal range for most small mammal species.

Direct monitoring of ultrafast electron and hole dynamics in perovskite solar cells.

Organic-inorganic hybrid perovskite solar cells have emerged as cost effective efficient light-to-electricity conversion devices. Unravelling the time scale and the mechanisms that govern the charge carrier dynamics is of paramount importance for a clear understanding and further optimization of the perovskite based devices. For the classical FTO/bulk titania blocking layer/mesoporous titania/perovskite/Spiro-OMeTAD (FTO/TPS) cell, further detailed and systematic studies of the ultrafast events related to exciton generation, electron and hole transfer, ultrafast relaxation are still needed. We characterize the initial ultrafast processes attributed to the exciton-perovskite lattice interactions influenced by charge transfer to the electron and hole transporters that precede the exciton diffusion into free charge carriers occurring in the sensitizer. Time-resolved transient absorption studies of the FTO/perovskite and FTO/TPS samples under excitation at different wavelengths and at low fluence 2 (μJ cm(-2)) indicate the sub-picosecond electron and hole injection into titania and Spiro-OMeTAD, respectively. Furthermore, the power-dependent femtosecond transient absorption measurements support the ultrafast charge transfer and show strong Auger-type multiparticle interactions at early times. We reveal that the decays of the internal trap states are the same for both films, while those at surfaces differ. The contribution of the former in the recombination is small, thus increasing the survival probability of the charges in the excited perovskite.

Mechanism of the reactions of alcohols with o-benzynes.

We have studied reactions of secondary and primary alcohols with benzynes generated by the hexadehydro-Diels–Alder (HDDA) reaction. These alcohols undergo competitive addition vs dihydrogen transfer to produce aryl ethers vs reduced benzenoid products, respectively. During the latter process, an equivalent amount of oxidized ketone (or aldehyde) is formed. Using deuterium labeling studies, we determined that (i) it is the carbinol C–H and adjacent O–H hydrogen atoms that are transferred during this process and (ii) the mechanism is consistent with a hydride-like transfer of the C–H. Substrates bearing an internal trap attached to the reactive, HDDA-derived benzyne intermediate were used to probe the kinetic order of the alcohol trapping agent in the H2-transfer as well as in the alcohol addition process. The H2-transfer reaction is first order in alcohol. Our results are suggestive of a concerted H2-transfer process, which is further supported by density functional theory (DFT) computational studies and results of a kinetic isotope effect experiment. In contrast, alcohol addition to the benzyne is second order in alcohol, a previously unrecognized phenomenon. Additional DFT studies were used to further probe the mechanistic aspects of the alcohol addition process.

The Research on the Effects of Electrical Aging on Trap Distribution in Polyethylene Doped with Nanoparticies

The photo-stimulated discharge (PSD) technology was used to characterize the trap distribution of polyethylene (PE) and the PE that doped with 5% MgO before and after electrical aging. For the PE with the aging time increasing, the internal shallow trap of the material gradually reduced and deep trap gradually increased. But for the PE that doped with 5% MgO with the aging time increasing, shallow trap gradually increased and the deep trap gradually reduced. Results show that: during the electrical aging process the PE produces a large amount of free radicals which can introduce deep traps. Adding impurity of MgO can effectively restrain charge moving that injected from electrode, thus to improve the internal electric field distortion of PE.