Opening Of Loop Research Articles

TopoSinGAN: Learning a Topology-Aware Generative Model from a Single Image

Generative adversarial networks (GANs) have significantly advanced synthetic image generation, yet ensuring topological coherence remains a challenge. This paper introduces TopoSinGAN, a topology-aware extension of the SinGAN framework, designed to enhance the topological accuracy of generated images. TopoSinGAN incorporates a novel, differentiable topology loss function that minimizes terminal node counts along predicted segmentation boundaries, thereby addressing topological anomalies not captured by traditional losses. We evaluate TopoSinGAN using agricultural and dendrological case studies, demonstrating its capability to maintain boundary continuity and reduce undesired loop openness. A novel evaluation metric, Node Topology Clustering (NTC), is proposed to assess topological attributes independently of geometric variations. TopoSinGAN significantly improves topological accuracy, reducing NTC index values from 15.15 to 3.94 for agriculture and 14.55 to 2.44 for dendrology, compared to the baseline SinGAN. Modified FID evaluations also show improved realism, with lower FID scores: 0.1914 for agricultural fields compared to 0.2485 for SinGAN, and 0.0013 versus 0.0014 for dendrology. The topology loss enables end-to-end training with direct topological feedback. This new framework advances the generation of topologically accurate synthetic images, with applications in fields requiring precise structural representations, such as geographic information systems (GIS) and medical imaging.

Artificial optoelectronic synapses based on flexible and transparent oxide transistors

The development of artificial optoelectronic synapses utilizing flexible, and transparent oxide transistors is crucial for advancing neuromorphic computing and wearable electronics. Here, we propose artificial optoelectronic synapses on flexible and transparent devices based on an ion-gel gated oxide transistor. The device consists of indium-tin-oxide/ion-gel thin film conformity fabricated on a polyethylene terephthalate substrate. The device exhibited a loop opening in current–voltage properties, and its operating mechanism was ascribed to charge trapping and de-trapping. The neuromorphic behaviors can also be simulated by this device for instance, namely ultraviolet (UV) induced short-term memory, long-term memory, paired-pulse facilitation, and learning/forgetting behaviors. Additionally, electrical habituation and UV potentiation were executed. This work paves the way for the realization of low-cost flexible and transparent synaptic wearable electronics.

Activation and friction in enzymatic loop opening and closing dynamics

Protein loop dynamics have recently been recognized as central to enzymatic activity, specificity and stability. However, the factors controlling loop opening and closing kinetics have remained elusive. Here, we combine molecular dynamics simulations with string-method determination of complex reaction coordinates to elucidate the molecular mechanism and rate-limiting step for WPD-loop dynamics in the PTP1B enzyme. While protein conformational dynamics is often represented as diffusive motion hindered by solvent viscosity and internal friction, we demonstrate that loop opening and closing is activated. It is governed by torsional rearrangement around a single loop peptide group and by significant friction caused by backbone adjustments, which can dynamically trap the loop. Considering both torsional barrier and time-dependent friction, our calculated rate constants exhibit very good agreement with experimental measurements, reproducing the change in loop opening kinetics between proteins. Furthermore, we demonstrate the applicability of our results to other enzymatic loops, including the M20 DHFR loop, thereby offering prospects for loop engineering potentially leading to enhanced designs.

Study protocol for a randomised open-label clinical trial examining the safety and efficacy of the Android Artificial Pancreas System (AAPS) with advanced bolus-free features in adults with type 1 diabetes: the ‘CLOSE IT’ (Closed Loop Open SourcE In Type 1 diabetes) trial

IntroductionMultiple automated insulin delivery (AID) systems have become commercially available following randomised controlled trials demonstrating benefits in people with type 1 diabetes (T1D). However, their real-world utility may be undermined...

Constitutive modelling and damage prediction of AlSi10Mg alloy manufactured by SLM technology with emphasis on ratcheting in LCF regime

The present work has been aimed at developing an improved cyclic plasticity model in the framework of Ohno-Wang kinematic hardening formulation and evaluating the performance of the model with reference to the critical experimental investigation. LCF test specimens of the AlSi10Mg aluminium alloy have been fabricated through selective laser melting technology. The material shows strain-range dependent variation of modulus of elasticity under symmetric strain-controlled loading. The modulus of elasticity decreases with increasing strain amplitude. Stress–strain responses have been critically examined under multistep uniaxial ratcheting in the LCF regime with incremental mean stress and stress amplitude. Damage calculation considering ratcheting and LCF mechanisms as independent gives unconservative predictions. The linear damage accumulation rule taking the largest contribution of both is bringing much more accurate estimates. The proposed model incorporates effects of mean stress and stress amplitude under uniaxial multistep ratcheting in the LCF regime. All fatigue tests in the LCF regime have been simulated using the proposed improved model. Evolution of strain-range dependent elastic modulus has been incorporated in the formulation of the improved model through the memory history dependent parameter. The ratcheting parameter is newly formulated in this present work to account for the effects of accumulated mean plastic strain on the opening of stress strain hysteresis loops that results in a better prediction of the behaviour of cyclic plastic deformation. The proposed model has been validated by comparing simulated results with experimental observations and reference published simulation results.

Adaptable photonic artificial neurons for attention-based object identification

The human visual system, reflected by its unique attention-dependent object recognition, holds remarkable potential. However, emulating the capabilities of the human visual system using typical two-terminal photodetectors is challenging. This is because these devices, which respond directly to optical and/or electrical stimuli, do not possess the adaptive and selective features inherent in bio-neuronal systems. In this study, we present a report of adaptable, attention-dependent object recognition utilizing gallium oxide-based photodetectors. The device demonstrates a pronounced hysteresis loop opening with an on/off ratio of less than 10 while maintaining ultra-low dark current levels below 10−10 A in its current-voltage curves. Notably, the on/off ratio can dynamically adjust to multilevel, > 102, and even rise to 103 under ultraviolet illumination. The observed results are attributed to the charge trapping and detrapping processes, as evidenced by detailed photocurrent mapping. Moreover, when subjected to simultaneous optical and electrical stimuli, the current first rises and subsequently falls post-peak, exhibiting neuron-like dynamics. These dynamics are subsequently used to emulate attention-based object identification by designing 3 × 3 array. Our findings present proof-of-concept photodetectors that emulate bio-neuronal object recognition systems, suggesting considerable potential for breakthroughs in areas like surveillance, remote sensing, medical imaging, and machine vision.

Polarity effects on wake‐up behavior of Al0.94B0.06N ferroelectrics

AbstractWurtzite ferroelectric materials are promising candidates for energy‐efficient memory technologies, particularly for applications requiring high operating temperatures. Asymmetric wake‐up behaviors, in which the polarization reversal depends both on polarity and cycle number for the first few dozen cycles, must be better understood for reliable device operation. Here, the detailed analysis of the asymmetric wake‐up behavior of thin film Al0.94B0.06N was performed combining time‐resolved switching measurements with Rayleigh analysis, piezoelectric measurements, and etching experiments of progressively switched samples. The analysis shows that the gradual opening of the polarization hysteresis loops associated with wake‐up is driven by a gradual increase in the domain‐wall density and/or domain‐wall mobility with electric field cycle to the polarity opposite to the growth polarity. The insights of this discovery will help to guide interface and polarity design in the eventual deployment of reliable devices based on these materials.

Russian Doll-like 3d-4f Cluster Wheels with Slow Relaxation of Magnetization.

The solvothermal reactions of LnCl3·6H2O and MCl2·6H2O (M = Co, Ni) with 2,2'-diphenol (H2L1) and 5,7-dichloro-8-hydroxyquinoline (HL2) gave three 3d-4f heterometallic wheel-like nano-clusters [Ln7M6(L1)6(L2)6(µ3-OH)6(OCH3)6Cl(CH3CN)6]Cl2·xH2O (Ln = Dy, M = Co, x = 3 for 1; Ln = Dy, M = Ni, x = 0 for 2; Ln = Tb, M = Ni, x = 0 for 3) with similar cluster structure. The innermost Ln(III) ion is encapsulated in a planar Ln6 ring which is further embedded in a chair-conformation M6 ring, constructing a Russian doll-like 3d-4f cluster wheel Ln(III)⸦Ln6⸦M6. 2 and 3 show obvious slow magnetic relaxation behavior with negligible opening of the magnetic hysteresis loop. Such a Russian doll-like 3d-4f cluster wheel with the lanthanide disc isolated by transition metallo-ring is rarely reported.

Fabrication and application prospects of Pr–Fe–B/Alnico nanocomposite alloys

The potentials of rare earth-based nanocomposite alloys have never been realized due to strict microstructural constraints. Owing to the easy demagnetization it is challenging to increase the soft magnetic phase content. To avoid the easy demagnetization, Pr–Fe–B/Alnico magnets were fabricated and reported in this manuscript. The content of the Alnico phase is increased from 0 to 25 wt%, while the content of Pr element is reduced to below the sub-stoichiometry of the 2:14:1 main phase. The maximum magnetic energy product, which is the figure-of-merit for permanent magnets, is increased from 122 kJ/m3 for the standard alloy to 146 kJ/m3 for the alloy with 15 wt% Alnico which shows a significant improvement considering the fact that the Curie point of the magnet is also increased by ∼66 K. The special microstructure contains distinctly and heterogeneously distributed 2:14:1 and Alnico phases. The dimensions of neither the 2:14:1 nor the Alnico phases meet the dimensional requirements of the nanocomposite magnets, but still the smooth demagnetization curves are noted for the alloys. The behavior of effective anisotropy, the performance of the magnets in applied magnetic field and the magnetic interactions among the various constituent grains were quantitatively studied by reversible susceptibility, irreversible susceptibility and recoil loop openness. This study may provide some guiding principles for the development of nanocomposite magnetic alloys with excellent magnetic properties by using much less RE elements.

A memphotoristor for high-efficiency temporal vision processing

A photodetector with history-dependent dynamical responses to optical inputs could offer an essential breakthrough in performing temporal vision processing and time-series prediction without the requirement for sophisticated circuitry and undesired high energy consumption. Till now, memristor dynamics and its effective modulation with photo illumination have been utilized to mimic bio-inspired vision processing. Despite significant effort, it is still challenging to process real-time analogue temporal optical information with high accuracy, which requires developing a photonic counterpart of the electric-triggered memristor. Here, we report on the development of a Ga2O3-based proof-of-concept memphotoristor, in which memristive dynamics were stimulated with ultraviolet photon flux rather than conventional voltage. Specifically, a distinct hysteresis loop opening appeared in the cyclic photocurrent-ultraviolet intensity curves, where the magnitude of the loop opening depends on the photon flux. Additionally, light-illumination-induced fading memory, nonlinearity, and temporal dynamics were successfully utilized to demonstrate in-sensor reservoir computation and time-series prediction with an accuracy of 98.86%. Our research will pave the way to developing a wide range of cutting-edge optoelectronics for various applications, such as photosensors, photonic memory storage, and neuromorphic vision sensing of objects in real time.

Novel comprehensive feedback theory—Part II: Unifying previous and new feedback models and further results

SummaryThe objective of this Part II of the paper on a novel feedback approach is that of unifying all the previous general feedback models within a single framework and of obtaining new results. In order to pursue this goal, we exploit the multiple possibilities of implementation of the generic three‐terminal circuit (TTC) that has to be inserted in the cut of the feedback loop when the cut‐insertion theorem (CIT) is applied for the analysis of the network. We present models based on a direct opening of the feedback loop inside the TTC, TTC implementations (associated with circuital examples) that allow an arbitrary splitting of the signal flow between a part associated to the feedback loop and another due to a direct leakage path from input to output, and methods (with exemplifying networks) based on test signal injection that allow measuring the gain of the closed feedback loop. The asymptotic formula of the overall gain is generalized to any network. Finally, examples of application to a voltage‐feedback amplifier are reported to show, in particular, the values and the properties of the multiple possible feedback loop gains that can be defined for a given cut and also to compare our results with those available in the literature.

Sensitive Fluorescent Determination of Nucleic Acids by a Cytosine-Rich Loop and Silver Nanoclusters in the Hybridization Chain Reaction (HCR)

Deep understanding of the effect of DNA sequence and structure on the fluorescent properties of DNA-templated silver nanoclusters (DNA–Ag NCs) affords alternative strategies for developing and exploiting DNA biosensors. DNA secondary structures (e.g., DNA loop) are essential for generating highly emissive DNA–Ag NCs. In this study, a cytosine-rich DNA loop was used as a facile template for the formation of silver nanoclusters. The fluorescence of silver nanocluster encapsulated within a cytosine-rich DNA loop was turned on by switching the size of the loop from large to small. Target nucleic acid served as the trigger for the hybridization chain reaction of hairpin probe 1 (H1) containing an inactivated cytosine-rich DNA loop with a large size at the ends and hairpin probe 2 (H2). Long-nicked double helices were obtained coupled with the opening of the large-size cytosine-rich DNA loop in H1 and switching to an activated cytosine-rich DNA loop with a small size. As a result, an increase in the fluorescent signal was observed. A sensitive detection limit of 10 pM and a linear detection range from 10 pM to 400 nM were obtained for nucleic acid determination. This facile assay provides a new approach capable of switching the fluorescence emission of DNA–Ag NCs for nucleic acid biosensing.

Inner relaxations in equiatomic single-phase high-entropy cantor alloy

The superior properties of high-entropy multi-functional materials are strongly connected with their atomic heterogeneity through many different local atomic interactions. The detailed element-specific studies on a local scale can provide insight into the primary arrangements of atoms in multicomponent systems and benefit to unravel the role of individual components in certain macroscopic properties of complex compounds. Herein, multi-edge X-ray absorption spectroscopy combined with reverse Monte Carlo simulations was used to explore a homogeneity of the local crystallographic ordering and specific structure relaxations of each constituent in the equiatomic single-phase face-centered cubic CrMnFeCoNi high-entropy alloy at room temperature. Within the considered fitting approach, all five elements of the alloy were found to be distributed at the nodes of the fcc lattice without any signatures of the additional phases at the atomic scale and exhibit very close statistically averaged interatomic distances (2.54-2.55 \r{A}) with their nearest-neighbors. Enlarged structural displacements were found solely for Cr atoms. The macroscopic magnetic properties probed by conventional magnetometry demonstrate no opening of the hysteresis loops at 5 K and illustrate a complex character of the long-range magnetic order after field-assisted cooling in $\pm$5 T. The observed magnetic behavior is assigned to effects related to structural relaxations of Cr. Besides, the advantages and limitations of the reverse Monte Carlo approach to studies of multicomponent systems like high-entropy alloys are highlighted.

Efficient degradation of bisphenol A by the UV-enhanced nano zero-valent iron-activated hydrogen peroxide advanced oxidation system

Bisphenol A (BPA) in a water environment has hazardous and is difficult to degrade under natural conditions. In this study, the UV-nZVI-H2O2 system was constructed to efficiently degrade BPA. The results show that the removal rate and mineralization rate of BPA were 85.03 % and 21.31 %, respectively, under the conditions of initial pH = 3, UV = 10 W, [nZVI] = 0.05 g/L, [H2O2] = 0.06 mmol/L, [BPA] = 40 mg/L and t = 60 min. This is mainly attributed to the synergistic effect among UV, nZVI and H2O2. The dominant reactive oxygen species in the UV-nZVI-H2O2 system was HO•, and the yield of HO• was up to 333.81 μmol/L, which was much higher than that of other systems in the controlled experiment. In addition, the system can efficiently remove a variety of aromatic and refractory organic matter (e.g., ibuprofen (IBU) and ciprofloxacin (CIP)). The reaction intermediates were identified, and it was speculated that the possible degradation pathways of BPA were mainly HO• attack on the electron-rich benzene ring in the BPA molecule and attack on the C–C bond connected between isopropyl and the benzene ring. The possible degradation pathways of IBU include decarboxylation, hydroxylation addition and single bond breaking. The possible degradation pathway of CIP is the loop opening of the piperazine ring and quinolone ring of CIP after continuous oxidation of HO•. The reaction mechanism of this system is a homogeneous and heterogeneous Fenton reaction and adsorption and precipitation of BPA by iron-based oxides.

Ultrafast self-assembly Fe2O3 nanoparticles confined in carbon layers toward robust heterogeneous electro-Fenton reaction

Heterogeneous electro-Fenton (EF) is a promising advanced oxidation process for refractory wastewater treatment. However, typical calcination or hydrothermal method for heterogeneous EF cathode fabrication is time-consuming, energy-consuming, or harmful to the environment. High-temperature shock (HTS) technique is a novel and rapid material synthesis method with the advantages of low-cost, eco-friendly. In this study, the electrodes named Fe2O3@C/carbon cloth (Fe2O3@C/CC), were synthesized by HTS for the first time within an extremely short time (∼5 s). The Fe2O3 nanoparticles with an average diameter of 61.90 ± 15.09 nm are uniformly dispersed on carbon cloth (CC) with the confinement and protection of the carbon layers. The as-prepared Fe2O3@C/CC cathode exhibited excellent electrocatalytic properties in the EF system. The removal efficiency of methylisothiazolinone (MIT) could reach 90.60 ± 1.70% in 40 min at a low current density of 1.11 mA cm−2 under the oxidation of the hydroxyl radical. In addition, the degradation pathways of MIT were further studied. According to the results of theoretical calculation, the –S–N– bond is the primary active site attacked during MIT degradation process. Therefore, heterocyclic loop opening is the main pathway of MIT degradation. HTS is an ultrafast and convenient potential technique compared with other cathode synthesis methods.

Photophysical Properties and Single‐Molecule Magnet Behavior in Heterobimetallic 3d4 f Schiff Base Complexes

AbstractThree new heterobimetallic Schiff base complexes of formula [(LZnCl)2Gd(H2O)](ZnCl4)0.5 (2), [(LZn(OH))(LZnCl)Sm(H2O)](ZnCl4)0.5 (3) and [(LZnCl0.5(OH)0.5)(LZnCl)Dy(H2O)](ZnCl4)0.5 (4) were designed from the reaction of the metallo‐ligand ZnL (1) (H2L=N, N′‐bis(3‐methoxysalicylaldiimine)‐1,3‐propylene‐2‐ol) and lanthanide salt in a ratio 1 to 1. The crystallographic structures of 2–4 were resolved by single crystal X‐ray diffraction. Light irradiation allowed the observation of a broad emission centered on the organic ligand which is exalted upon Zn(II) coordination. 1 is able to act as a metallo‐organic chromophore for the sensitization of the Sm(III) luminescence. Finally the Dy(III) derivative displayed Single‐Molecule Magnet (SMM) behavior with an opening of the hysteresis loop up to 5 K and a magnetic relaxation operating through Orbach, Raman and Quantum Tunneling of the Magnetization (QTM) at 0 Oe while under an applied magnetic field the QTM is efficiently cancelled.

The Y\u03a6 motif defines the structure-activity relationships of human 20S proteasome activators

The 20S proteasome (20S) facilitates turnover of most eukaryotic proteins. Substrate entry into the 20S first requires opening of gating loops through binding of HbYX motifs that are present at the C-termini of certain proteasome activators (PAs). The HbYX motif has been predominantly characterized in the archaeal 20S, whereas little is known about the sequence preferences of the human 20S (h20S). Here, we synthesize and screen ~120 HbYX-like peptides, revealing unexpected differences from the archaeal system and defining the h20S recognition sequence as the Y-F/Y (YФ) motif. To gain further insight, we create a functional chimera of the optimized sequence, NLSYYT, fused to the model activator, PA26E102A. A cryo-EM structure of PA26E102A-h20S is used to identify key interactions, including non-canonical contacts and gate-opening mechanisms. Finally, we demonstrate that the YФ sequence preferences are tuned by valency, allowing multivalent PAs to sample greater sequence space. These results expand the model for termini-mediated gating and provide a template for the design of h20S activators.

Artificial Nociceptor Using Liquid Ionic Memory

AbstractThe incorporation of the different functions of a biological nervous system into electronic devices is challenging in the realization of humanoid robotics, which can recognize and respond in a manner that is similar to humans. Emerging synaptic devices that can process electronic signals by neuromorphic functions that operate in a similar manner to that of biological nervous systems. In this study, an acid‐sensitive artificial nociceptor device, which simultaneously detects acid concentration and generates synaptic signals, is developed for electronic nose application. The transition metal oxide (WO3)‐based device electrochemically performs neuromorphic sulfuric acid (H2SO4) sensing. The current–voltage curves demonstrate loop opening, with the change in the molarity of the acid, indicating memory storage ability and tunability of the developed nociceptor device.

Structural and Optical Characterization of Silica Nanospheres Embedded with Monodisperse CeO2-Eu3+ Nanocrystals

Luminescent nanocrystals embedded into silica microspheres were shown to be useful for silica labeling for biological applications, ensuring mechanical and chemical stability, nontoxicity, biocompatibility and optical properties. We used sol–gel technology to prepare silica nanospheres embedded with fluorescent and magnetic Eu3+(1 mol%)-doped CeO2 nanocrystals. The X-ray diffraction pattern analysis and transmission electron microscopy investigations showed CeO2:Eu3+(1 mol%) nanocrystals of about 9 nm size and Ce3+ ions substitution by the Eu3+ ions; the nanocrystals dispersed inside the nanosized silica spheres of about 400 nm diameters. The photoluminescence spectra recorded under UV-light excitation showed Eu3+ ions luminescence peaks (5D0-7FJ, J = 0–4) accompanied by a weaker 425 nm luminescence due to the silica matrix; the quantum yield was 0.14. The weak hysteresis loop and magnetization curves recorded up to 20,000 Oe showed dominantly paramagnetic behavior associated with the silica matrix; a slight opening of the hysteresis loop to a very small magnetic field (about 0.005 Oe) was due to the presence of the two rare earth ions. The photonic crystal properties of SiO2-CeO2:Eu3+(1 mol%) silica nanospheres deposited as films on quartz plates were revealed by the two weak attenuation peaks at 420 and 500 nm and were associated with the reflection from different planes. The SiO2-CeO2:Eu3+(1 mol%) nanospheres are attractive potential candidates for photonics-related applications or for multifunctional bio-labels by combining the luminescence and magnetic properties of the nanocrystals.

Hairpin oligosensor using SiQDs: Förster resonance energy transfer study and application for miRNA-21 detection.

MicroRNAs are known to be tumor suppressors and promoters and can be used as cancer markers. In this work, a novel oligosensor was designed using Si quantum dots (SiQDs) for the detection of miRNAs. Five-nanometer SiQDs were synthesized, with a band gap of 2.8eV, fluorescence lifetime of 4.56μs (τ1/2 = 3.26μs), quantum yield of 25%, fluorescence rate constant of 6.25 × 104, and non-radiative rate constant of 1.60 × 105s-1. They showed excellent water dispersibility, good stability (with 95% confidence for 6-month storage) without photobleaching, and high biocompatibility, with an IC50 value of 292.2μg/L. The SiQDs and Black Hole Quencher-1 (BHQ1) were conjugated to the 5' and 3' terminals of an oligomer, respectively. The resulting hairpin molecular beacon showed resonance energy transfer efficiency of 63%. A distance of 0.91 R (Förster distance) between SiQD and BHQ1 was obtained. In the presence of a stoichiometric amount of the complementary oligonucleotide (ΔGhybridization = -35.09kcalmol-1), 98% of the fluorescence was recovered due to loop opening of the hairpin structure. The probe showed good selectivity toward miRNA-21, with a limit of detection of 14.9 fM. The oligosensor recoveries of miRNA-21 spiked in human serum and urine were 94-98% and 93-108%, respectively.