Resistance State Research Articles

Pancreatic volume, fat content and T1 relaxation time using magnetic resonance imaging in patients with prior gestational diabetes mellitus.

To compare the volume, fat content, and T1 relaxation time of the pancreas in participants with and without prior gestational diabetes mellitus (GDM). In this prospective case-control study, we enrolled 29 women with prior GDM, and divided them into three groups (normoglycemic, prediabetic, and diabetic) based on their glycaemic status in the postpartum period; and a group of 13 participants as controls who had normoglycemia during pregnancy. Participants underwent MR examination including an axial multi-echo DIXON-based sequence and an axial-oblique T1 mapping sequence. The average proton density fat fraction (PDFF) and T1 value of the pancreas were measured by drawing multiple circular regions of interest (ROIs). Average hepatic PDFF was similarly calculated. Pancreatic volume was computed by summating cleaned freehand ROIs outlining pancreatic parenchyma. Women were evaluated at a mean age of 32.9 ± 4.0 years and with a mean BMI of 25.2 ± 2.9kg/m2. The median (IQR) duration of follow-up after childbirth was 24 (34-44) months. In controls, the pancreatic PDFF, T1 value, and volume were 5.4 ± 2.3%, 850.6 ± 101.6 ms, and 69.3 ± 16.2cm³, respectively, while in subjects with a history of GDM, these values were 4.7 ± 2.0%, 844.6 ± 91.8 ms, and 69.8 ± 16.6cm³, respectively. No statistical differences were observed (all p > 0.05). Mean hepatic PDFF was significantly higher in the diabetic and prediabetic groups (12.2 ± 6.4% and 11.0 ± 7.6% respectively) than in the control and normoglycemic groups (7.9 ± 7.3 and 4.7 ± 1.6% respectively; p -0.01). We did not find any significant changes in pancreatic volume, fat content, or fibrosis in women with prior GDM and with different glycaemic categories when evaluated in the early postpartum period, compared to the control group. These findings may be a consequence of the transient state of insulin resistance in GDM and the finite duration of the disease course in new-onset prediabetes and diabetes patients.

Printed High-Entropy Prussian Blue Analogs for Advanced Non-Volatile Memristive Devices.

Non-volatile memristors dynamically switch between high (HRS) and low resistance states (LRS) in response to electrical stimuli, essential for electronic memories, neuromorphic computing, and artificial intelligence. High-entropy Prussian blue analogs (HE-PBAs) are promising insertion-type battery materials due to their diverse composition, high structural integrity, and favorable ionic conductivity. This work proposes a non-volatile, bipolar memristor based on HE-PBA. The device, featuring an active layer of HE-PBA sandwiched between Ag and ITO electrodes, is fabricated by inkjet printing and microplotting. The conduction mechanism of the Ag/HE-PBA/ITO device is systematically investigated. The results indicate that the transition between HRS and LRS is driven by an insulating-metallic transition, triggered by extraction/insertion of highly mobile Na+ ions upon application of an electric field. The memristor operates through a low-energy process akin to Na+ shuttling in Na-ion batteries rather than depending on formation/rupture of Ag filaments. Notably, it showcases promising characteristics, including non-volatility, self-compliance, and forming-free behavior, and further exhibits low operation voltage (VSET = -0.26 V, VRESET = 0.36 V), low power consumption (PSET = 26 µW, PRESET = 8.0 µW), and a high ROFF/RON ratio of 104. This underscores the potential of high-entropy insertion materials for developing printed memristors with distinct operation mechanisms.

Evaluation and External Driving Factors Analysis of Water–Energy–Food Resilience Security—Based on Spatial Durbin Model and Four Provinces Along the Yellow River

Research on water–energy–food security is crucial for ensuring the sustainable development of human society. Building on the water–energy–food theory and resilience concepts, a novel perspective termed “resilience security” was proposed. This differs from traditional approaches focused on coordination security and efficiency security. An indicator evaluation system consisting of 29 indicators was developed. Panel data from 2009 to 2022 in 40 cities across Shandong, Shanxi, Henan, and Shaanxi Provinces along the Yellow River were used to assess local water–energy–food resilience security. The nine external driving factors were empirically analyzed in different provinces using a spatial Durbin model. The findings indicate that: (1) over the 14-year period, the water––energy–food resilience security of the sample transitioned from a near-exposure state to an initial resistance state; and (2) over the 14-year period, administrative power, market power, resource flow capacity, population density, industrial structure, urbanization level, scientific and technological inputs, environmental governance inputs, and spatial geographic factors significantly influenced regional water–energy–food resilience security, with notable variations across provinces.

Multilevel Optical Storage, Dynamic Light Modulation, and Polarization Control in Filamented Memristor System.

The electrochemical metallization (ECM) mechanism is emerging as a promising approach for the development of optical memristors-nonvolatile memory systems proposed for use as artificial synapses in neuromorphic computing applications. ECM memristors offer exceptional operating dynamics and power efficiency compared to other systems, but challenges with reproducible cycle-to-cycle state switching and the absence of advanced optical functionalities hinder their integration into photonic systems. In this work, an ECM free-standing memristor structure is proposed, which simultaneously offers wavelength-dependent multilevel nonvolatile optical storage, volatile light modulation, and dynamic polarization control. It is demonstrated that in the presence of a resonance, the optical readout provides noise-free, robust, and significantly more accurate information about the memristor's state than electrical measurement. The use of light allows to gain insight into the intermediate electrical levels of the device as it transitions between high and low resistance states and to recover the complete record of applied voltages even when stochastic filament ruptures occur. Finally, the investigations show that spectroscopic ellipsometry provides real-time information on the dynamics of cation movement and the corresponding permittivity changes at the interfaces between the switching layer and the electrodes, thus becoming a complementary characterization method for ECM memristors alongside state-of-the-art techniques.

Coexistence of analog and digital resistive switching behaviors in TiN/SiNx resistive random access memory device

The digital–analog hybrid resistive random access memory can not only be used in computing in memory integrated circuits but also adapt to various requirements, such as achieving lower integration complexity. In this work, resistive memory devices with Ta/SiNx/TiN/Pt structures were fabricated, which exhibit a gradual analog or abrupt digital resistive state (DRS) characteristic depending on the different applied voltage range. The experimental results indicate that different RS switching of these devices is due to the change in the conductive mechanism in the SiNx/TiN double-layer structure. The Schottky barrier at the SiNx/TiN interface is the cause of analog resistive state characteristics under low sweeping voltage, while the formation/rupture of the conductive filaments formed under large voltage is the reason for the device to exhibit DRS characteristics.

Abstract PR004: Age-induced chronic accumulation of glucocorticoids drives therapy resistance in lung cancer

Abstract Non-small cell lung cancer (NSCLC), a highly aggressive cancer, is the leading cause of cancer- related deaths in the U.S. While chemotherapy and targeted therapy are the main treatment modalities in the clinic, many patients do not respond to these treatments. Strikingly, the median age for lung cancer diagnosis is 71. Yet, preclinical and clinical research have largely been skewed towards young mice and patients. Here, we address this gap in knowledge and evaluate if old age affects the response to standard of care NSCLC therapies in KRAS-driven NSCLC. Using human sera from young and old healthy subjects to treat NSCLC cell lines, we show that age-driven circulatory changes are sufficient to drive a state of profound resistance to both chemotherapies as well as KRASG12C targeted therapies. We confirmed the relevance of our findings in vivo, by transplanting cancer cells derived from the K-rasLSL-G12D/+; p53fl/fl genetically engineered mouse model of lung cancer into young and old C57BL/6 mice. Using this model we showed that unlike young lung tumor-bearing mice on chemotherapy, old tumor-bearing mice do not respond to treatment and have a poor prognosis. Mechanistically, we found that old age drives a transcriptional reprogramming that favors drug resistance and identified the glucocorticoid receptor as a major driver of these transcriptional changes. We traced this to an age-induced chronic accumulation of glucocorticoids in circulation and within the tumor interstitial fluid. Chronic treatment with age-relevant concentrations of cortisol alone was sufficient to drive glucocorticoid receptor activation and induce resistance to therapies mirroring the effects of old age. Further supporting a driving role for glucocorticoids in driving age- induced drug resistance, blocking the glucocorticoid receptor genetically or pharmacologically rescues the drug resistance state imposed by old age in NSCLC cells. Lastly, using TCGA patient data we show an inverse correlation between glucocorticoid receptor activation (GR score) and progression-free survival of lung cancer patients. Together, our work demonstrates a role for age-induced glucocorticoids in circulation in promoting therapy-resistance in NSCLC patients and supports the use of therapeutic agents that block the glucocorticoid receptor as a strategy to increase therapy efficacy in NSCLC patients. Citation Format: Devesh Raizada, Felicia Lazure, Stanislav Drapela, Nadir Sarigul, Joanne Tejero, Didem Ilter, Ana Da Silva Gomes. Age-induced chronic accumulation of glucocorticoids drives therapy resistance in lung cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr PR004.

Graphene Oxide-Doped Indium Oxide Buffer Film Sandwiched between Titanium Oxide Layers for the Development of Photosensitive Resistive Memory Devices.

Over the past decade, metal oxide semiconductors have attracted considerable attention because of their transparency, high intrinsic charge carrier mobility, and charge carrier density. Metal oxide semiconductors also provide a promising route to develop resistive memory devices because of the tunability of their conductivity via the removal of oxygen ions, forming oxygen vacancies that can act as electron donors. Here, this paper reports the fabrication of a resistive random-access memory (ReRAM) device with TiO2 and TiO2-x layers and introduces a solution-processed In2O3-graphene oxide (GO) buffer layer from a water-based precursor solution to tune the switching characteristics. The devices were compared with a ReRAM device with no buffer layer, and the device composition was optimized by tuning the GO concentration in the layers. The devices showed hysteresis under cyclically scanned bias between positive and negative voltages with clear switching between the low resistance state (LRS) and the high resistance state (HRS). The optimized device also showed a more than 3 orders of magnitude difference in resistance between the LRS and HRS and a stable current retention. The devices also showed photoresponsive behaviors. In the LRS, the current increased significantly under illumination, while in the HRS, the current deteriorated slowly when constantly illuminated. These results highlight the dual role of the GO flakes in the buffer layer by increasing the resistance in the HRS and providing a photoresponsive switching capability. The ReRAM device was connected to a TFT device, and its feasibility as a memory component in a digital circuit was successfully demonstrated. These results provide a new avenue for developing metal-oxide-based ReRAM devices with GO-containing active layers.

Enhancing Uniformity, Read Voltage Margin, and Retention in Three-Dimensional and Self-Rectifying Vertical Pt/Ta2O5/Al2O3/TiN Memristors.

This study introduces a Ta2O5-based self-rectifying memristor (SRM) with an Al2O3 interfacial layer adopted to improve switching uniformity, read voltage margin, and long-term retention. The Pt/Ta2O5/Al2O3/TiN (PTAT) device exhibits a 105 rectification ratio, 104 on/off ratio, 2 × 106 endurance, and retention of 104 s at 150 °C. A 3-layer 4 × 4 vertical resistive random access memory structure exhibits uniform switching parameters. The coefficient of variation (CV) for device-to-device measurements is 0.23 for the low resistance state (LRS) and 0.22 for the high resistance state (HRS), while for cycle-to-cycle measurements, the CV is 0.38 for the LRS and 0.11 for the HRS. Finally, the present study demonstrates the superior performance of the PTAT devices in the context of hardware-aware training for a fully connected neural network implementation. These advancements position the PTAT device as a promising candidate for high-density three-dimensional storage class memory and low-power neural networks, offering the consistent performance and reliability necessary for future high-density storage applications.

Impact of Light on Coexistence of Memresistance, Meminductance, and Memcapacitance (MEMRIC) in Nanostructured Copper Oxide (CuO) Based Random Access Memory Devices.

We demonstrated the coexistence of memresistance, memcapacitance, and meminductance non-volatile bipolar analog resistive switching in Cu (top electrode)/CuO (active layer)/SS (bottom electrode) memory devices with and without presence of the light. The onset of memcapacitance and meminductance is noticed from the pinched-shaped characteristics in the first and third quadrants. The variation in the scan rate also impacts the coexistence characteristics by shifting the intercept point for low resistance (LRS) and high resistance (HRS) states in positive and negative biasing voltages. The durability and retention are measured over a period of 150 cycles and 1500 s with and without light illumination. The slopes for the Weibull cumulative distribution plot for set/reset state with and without light are 106.80/114.23 and 70.21/102.25, respectively, suggesting that the stability of the device increases with light illumination. Interestingly, the memcapacitance disappears after 600 cycles and after 60 . The double logarithmic I-V characteristics suggest the trap-assisted conduction (higher slope >2) in the higher external electric field, and Ohmic behavior in the lower applied field region. Thus, the present study provides a way for low-power electronics and photoresistors together with memresistance, memcapacitance, and meminductance, simultaneously, i. e., MEMRIC in a single device.

Bioactive Ion‐Confined Ultracapacitive Memristors with Neuromorphic Functions

AbstractThe field of bioinspired iontronics, bridging electronic devices and ionic systems, has multiple biological applications. Carbon‐based ultracapacitive devices hold promise for controlling bioactive ions via electric double layers due to their high‐surface‐area and biocompatible porous carbon electrodes. However, the interplay between complex bioactive ions and porous carbons remains unclear due to the variety of structures of bioactive ions present in biological systems. Herein, we investigate the adsorption behavior of a series of bioactive ammonium‐based cations with varying alkyl chain lengths in nanoporous carbons. We find that strong physisorption results from the synergistic hydrophobic interaction and electrostatic attraction between porous carbons (with a negative zeta potential) and bioactive cations. Bioactive cations with varying alkyl chain lengths can be irreversibly physically adsorbed and confined within nanoporous carbons resulting in anion enrichment and depletion during electric polarization. This situation, in turn, results in a characteristic memristive behavior in all‐carbon capacitive ionic memristor devices. Our findings highlight the relationship between the resistance state of the memristor and ion adsorption mechanisms in all‐carbon capacitive devices, which hold potential for future transmitter delivery, biointerfacing, and neuromorphic devices.

Solution-Processed TiO2/ZnFe2O4 Heterostructure for Stable Multilevel Memristor with Room-Temperature Reactive Gas Selectivity.

Solution-processed oxide-based heterojunctions that work in diverse directions will be ideal alternatives for cost-effective, stable, and multifunctional devices. Here, we have reported a stable multilevel resistive switching (RS) at the solution-processed TiO2/ZnFe2O4 heterointerface with endurance stability over 104 cycles and retention over 105 s. It can maintain the switching after dripping water onto the device, followed by drying at 100 °C and at an operating temperature of up to 200 °C. As the switching mechanism is governed by filamentary and interface-dominated charge conduction, our device shows additional tunability in the low resistance state (LRS) by changing environmental conditions. The inability to form filaments results in almost negligible switching under a vacuum or inert environment with an LRS loss. Meanwhile, the presence of reducing gas leads to a depletion layer lowering at the TiO2/ZnFe2O4 heterointerface by removing the surface-adsorbed oxygen molecules that help filament conduction through the interface and, hence, a change in LRS. Furthermore, different reaction capacities of different reactive gas environments with the surface-adsorbed oxygen molecule lead to discrete ON-OFF ratios, presenting a pathway to identify several reactive vapors like ammonia, formaldehyde, and acetone at room temperature and presenting a new approach for integrating RS and room temperature gas sensing in the multifunctional device technology.

Ultrafast reconfigurable direct charge trapping devices based on few-layer MoS2

Abstract Charge trapping devices incorporating 2D materials and high-κ dielectrics have emerged as promising candidates for compact, multifunctional memory devices compatible with silicon-based manufacturing processes. However, traditional charge trapping devices encounter bottlenecks including complex device structure and low operation speed. Here, we demonstrate an ultrafast reconfigurable direct charge trapping device utilizing only a 30 nm-thick Al2O3 trapping layer with a MoS2 channel, where charge traps reside within the Al2O3 bulk confirmed by transfer curves with different gate-voltage sweeping rates and photoluminescence (PL) spectra. The direct charging tapping device shows exceptional memory performance in both three-terminal and two-terminal operation modes characterized by ultrafast three-terminal operation speed (≈300 ns), an extremely low OFF current of 10-14 A, a high ON/OFF current ratio of up to 107, and stable retention and endurance properties. Furthermore, the device with a simple symmetrical structure exhibits VD polarity-dependent reverse rectification behavior in the high resistance state (HRS), with a rectification ratio of 105. Additionally, utilizing the synergistic modulation of the conductance of the MoS2 channel by VD and VG, it achieves gate-tunable reverse rectifier and ternary logic capabilities.

Solving mystery with the Meissner state in La3Ni2O7-δ

Recently, zero resistance state in highly compressed La3Ni2O7-δ has been observed. However, all attempts of many research groups to detect the Meissner state in the La3Ni2O7-δ have been failed. To explain this puzzle, an exotic superconducting state (for instance, filamentary superconductivity) in the La3Ni2O7-δ has been supposed. Here, I extracted temperature dependent self-field critical current, Ic(sf,T), dataset from current-voltage curves and performed the Ic(sf,T) analysis. As a result, I found that highly compressed La3Ni2O7-δ to exhibits d-wave superconductivity with the gap-to-transition temperature ratio 2Δ(0)/(kBTc) = =4.0 ± 0.3, a very large ground state London penetration depth, λ(0, P = 16.6 GPa) = 6.0 μm, and a very high Ginzburg-Landau parameter k(0, P = 16.6 GPa) = 1500. This implies that the ground state lower critical field Bc1(0, P = 16.6 GPa) = 34 μT is of the same order as the Earth’s magnetic field. Based on this, to detect the Meissner state in the La3Ni2O7-δ becomes a very challenging task. I can hypothesize that the magnetic flux trap effect recently proposed to eliminate the diamond anvil cell (DAC) background in experiments on magnetic properties of the superconducting hydrides can also apply in studies of magnetic properties in the La3Ni2O7-δ superconductor.

Machine Learning Enabled High‐Throughput Screening of 2D Ultrawide Bandgap Semiconductors for Flexible Resistive Materials

AbstractThe 2D ultrawide bandgap (UWBG) semiconductors have attracted great attentions for the next generation of electronics and optoelectronics, owing to their superiority on material flexibility, device stability, and power consumption. However, few 2D UWBG semiconductors have been discovered, impeding their prosperous developments and widespread applications. Here, a high‐throughput workflow is constructed to screen 2D UWBG semiconductors assisted by machine learning, and 507 potential candidates are obtained. Moreover, by learning, predicting, and screening Young's modulus and Poisson's ratio, 31 flexible 2D UWBG semiconductors are identified. Then the generation and the diffusion of anion vacancies, as well as the corresponding electronic properties are investigated by using the first‐principles calculations, and 3 of them are demonstrated as the most promising candidates for the flexible resistive materials. The facile interface tunneling and the increased material conductance caused by the anion vacancies will contribute to the transition from high resistive state to low resistive state. This work provides an efficient high‐throughput screening protocol to enrich the family of 2D UWBG semiconductors and is expected to foster their practical applications.

A diffusive memristor with two dimensional ZrCl2

Layered transition metal halides have been identified as potential materials for memristors due to their distinctive structure and exceptional electrical properties. However, systematic studies on their preparation processes and properties have been scarce in recent years. This study marks a significant milestone as it successfully synthesizes two-dimensional layered ZrCl2 nanomaterials using chemical vapor deposition techniques. Subsequently, an Ag/ZrCl2/Au diffusion memristor was fabricated utilizing the synthesized ZrCl2 material, followed by comprehensive performance evaluations. The results demonstrate that under DC voltage conditions, the memristor exhibits stable abrupt resistive switching behavior, with a high resistance state to low resistance state ratio reaching up to 103; this stability persists even after 9×104 cycles. Furthermore, after approximately 1000 operating cycles, the memristor displays gradual resistance switching behavior characterized by continuous changes in its resistance value corresponding to variations in voltage levels. Notably, this study successfully emulates key features of biological nociceptors such as "threshold," "no adaptation," and "plasticity." A proposed mechanism based on silver ion migration elucidates the observed resistance switching phenomenon. These research findings underscore broad application prospects for 2D transition metal halides within the realm of memristors, while also offering a novel approach towards developing high-performance and long-life neuromorphic computing devices.

Feasibility study of analogue filters based on memristor

AbstractThis paper reports the critical parameters in fitting the Al:HfO2 memristor and exploits the memristor symbol derived from this fitting to design filter circuits. Memristor‐based filters can obtain at least two different filter ranges with the same filtering effect as conventional filters. Multistate resistance can be achieved by controlling the filamentary gap; adjusting the initial gap in the high resistance state from 1 to 0.1 nm could vary the cut‐off frequency of the filters from 230 MHz to 1.54 GHz. Memristor‐based band‐pass filter is also simulated by cascading a low‐pass filter and a high‐pass filter; the results show that a cut‐off frequency of 5.46 to 22.22 GHz can be tuned by adjusting the initial gap of a low resistance state from 0.4 nm down to 0.2 nm. Replacing the resistor in a conventional filter with a memristor allows the filter to have a variable range; this would solve the limitation where the conventional analogue filters have only a single filter range due to the fixed values of their constituent elements.

Sliding Ferroelectricity Induced Ultrafast Switchable Photovoltaic Response in ε-InSe Layers.

2D sliding ferroelectric semiconductors have greatly expanded the ferroelectrics family with the flexibility of bandgap and material properties, which hold great promise for ultrathin device applications that combine ferroelectrics with optoelectronics. Besides the induced different resistance states for non-volatile memories, the switchable ferroelectric polarizations can also modulate the photogenerated carriers for potentially ultrafast optoelectronic devices. Here, it is demonstrated that the room temperature sliding ferroelectricity can be used for ultrafast switchable photovoltaic response in ε-InSe layers. By first-principles calculations and experimental characterizations, it is revealed that the ferroelectricity with out-of-plane (OOP) polarization only exists in even layer ε-InSe. The ferroelectricity is also demonstrated in ε-InSe-based vertical devices, which exhibit high on-off ratios (≈104) and non-volatile storage capabilities. Moreover, the OOP ferroelectricity enables an ultrafast (≈3ps) bulk photovoltaic response in the near-infrared band, rendering it a promising material for self-powered reconfigurable and ultrafast photodetector. This work reveals the essential role of ferroelectric polarization on the photogenerated carrier dynamics and paves the way for hybrid multifunctional ferroelectric and optoelectronic devices.

Human body resistance dynamics in the post-covid period

The issue of the state of specific and nonspecific resistance in the post-COVID period and the possible consequences of COVID-19 remains poorly understood. A clinical and laboratory examination of 124 patients was conducted at various time points after COVID-19 infection. 62 patients recovered completely and 62 had post-COVID syndrome. The leukocyte count and leukogram were evaluated in all patients. Immunogram parameters were additionally evaluated in patients with post-COVID syndrome. The results showed that, regardless of post-COVID syndrome, leukocyte count is lower in all patients within six months after COVID-19 infection than in unaffected subjects. The absolute neutrophil count is restored only 12 months later. In the presence of post-COVID syndrome, the absolute number of CD3+, CD4+and CD19+lymphocytes was lower than in healthy people. At the same time, 3 to 15 months after that, IgA titer in patients with PCS was significantly lower and that of for total IgM and IgG was higher without any clinical or laboratory signs of inflammation. The total blood IgE level was significantly higher and increased by the end of the observation period. A decreased activity of nonspecific protection, as well as indicators of cellular and humoral immunity in patients with post-COVID syndrome is accompanied by higher rate of viral and bacterial infections of various localization. Whereas during the first period an increase in total blood ID is not accompanied by clinical signs of atopy, then 6 months later the frequency of allergy increases. During the same period, cases of a joint syndrome revealed as arthralgia or progressive joint destruction become more frequent. Atopic manifestations are often combined with joint syndrome. Thus, after a COVID-19 infection, a low long-term level of nonspecific protection remains in vivo. In patients with post-COVID syndrome, low nonspecific and specific body resistance is manifested by viral and bacterial infections of the mucous membranes and skin. An imbalance in the immune system contributes to developing allergic and autoimmune processes.

Defining a pattern in the loss of integrity by ribbed plates under fire conditions

This paper reports a study aimed at assessing fire resistance of reinforced concrete ribbed slabs at the onset of integrity loss limit state. EN 1992-1-2 lacks calculation methodology for determining the limit of fire resistance of reinforced concrete slabs when the limit state of integrity loss occurs. Scientific works are focused on two limit states of fire resistance: load-bearing capacity and heat-insulating capacity. Experimental tests are criticized because of difficulties in registering signs of the onset of the limit state of loss of integrity, in particular due to the need to control the unheated surface of the ribbed plate during a fire under the action of mechanical load. Therefore, there is no calculation methodology for assessing the fire resistance of reinforced concrete ribbed slabs upon the onset of the limit state of loss of integrity. At the same time, to ensure the safe evacuation of people in the event of a fire, to prevent the spread of fire, as well as to carry out the effective work of rescuers, it is necessary to use building structures with guaranteed fire resistance classes. The paper reports the results of solving thermal engineering and static problems, which relate to the temperature distribution and stress-strain state of the investigated ribbed plate. Conducting research into the fire resistance of reinforced concrete ribbed slabs, taking into account the onset of the limit state of loss of integrity, made it possible to establish the dependence of the fire resistance limit of these structures on the loss of integrity on the level of applied mechanical load. The resulting dependence plot makes it possible to evaluate reinforced concrete ribbed slabs according to the criterion of the onset of the limit state of loss of integrity, which provides an opportunity to determine fire resistance more objectively

Optical control of multiple resistance levels in graphene for memristic applications

Neuromorphic computing has emphasized the need for memristors with non-volatile, multiple conductance levels. This paper demonstrates the potential of hexagonal boron nitride (hBN)/graphene heterostructures to act as memristors with multiple resistance states that can be optically tuned using visible light. The number of resistance levels in graphene can be controlled by modulating doping levels, achieved by varying the electric field strength or adjusting the duration of optical illumination. Our measurements show that this photodoping of graphene results from the optical excitation of charge carriers from the nitrogen-vacancy levels of hBN to its conduction band, with these carriers then being transferred to graphene by the gate-induced electric field. We develop a qualitative model to describe our observations. Additionally, utilizing our device architecture, we propose a memristive crossbar array for vector-matrix multiplications.