Unit Charge Research Articles

Structurally Innovative Benzimidazole‐fused Ionic Organoselenium Compounds: Prevalence of Se···N/Se Chalcogen Bonds with the Selenocyanate Receptor

The non‐covalent interactions in molecules play important roles towards their applications in various aspects such as molecular recognition, catalysis, supramolecular chemistry, structural biology, pharmacology etc. Interestingly, among various non‐bonding interactions, chalcogen bonding (ChB) has been extensively studied in different facets of crystal engineering over the last several years. The present study demonstrates the presence of Se···N or Se···Se ChB in the benzimidazole‐fused cyclic selenazonium selenocyanates (6‐8), cyclic selenazinium selenocyanates (9‐10) and the acyclic benzimidazolium analogs having two different types of selenocyanate units (11‐12). The final organoselenium compounds were synthesized from benzimidazole in several steps in reasonably good yields. The single crystal X‐ray structures of the compounds revealed that both the N atom and Se atom of the negatively charged SeCN unit act as ChB acceptors in building the Se···N or Se···Se ChB interactions along with the additional hydrogen bonding (HB) interactions. Moreover, the structural optimization and natural bond orbital (NBO) analyses were carried out using density functional theory (DFT) to calculate the natural charges on different Se centers and the strength of second‐order perturbation energy (E2) for the ChB interactions. Finally, electrostatic potential surface (SEP) of the compounds was developed to visualize the formation of σ‐holes.

Electrostatic Assembly of Gold Nanoclusters in Reverse Emulsion Enabling Nanoassemblies with Tunable Structure and Size for Enhanced NIR-II Fluorescence Imaging.

The precise control of the assembly structure and size of gold nanoclusters (AuNCs) can potentially amplify their near-infrared II (NIR-II) fluorescence imaging and targeting properties. However, the conventional electrostatic assembly of AuNCs and charged molecules faces challenges in balancing the inherent electrostatic repulsions among charged units and regulating the diffusion of assembly units. These difficulties limit precise control over assembly size and structure, along with limited options for coassembled molecules, thereby restricting imaging properties and targeting capability. To circumvent this challenge, we developed a reverse emulsion-confined electrostatic assembly method. This technique efficiently constructs AuNC nanoassemblies with diverse coassembled molecules, allowing for the fine-tuning of assembly size and structure, including both core-satellite and homogeneous AuNC nanoassemblies. The development of two distinct nanoassemblies can be partially attributed to the varying diffusive rates of AuNCs or the AuNCs/polymer complex within the fused emulsion droplets. This variance arises from steric hindrances encountered during the emulsion fusion process. Interestingly, core-satellite nanoassemblies exhibit the strongest NIR-II fluorescence enhancement. Finally, the introduction of a hyaluronic acid coating on the surfaces of nanoassemblies with varying sizes enables the nanoprobes to achieve enhanced lymph node imaging through size modulation and macrophage targeting, which are used for surgical navigation to remove lymph node metastases. We envision that this self-assembly strategy can be extended to a wide range of electrostatic assembly systems for the development of multicomponent functional materials.

Adaptive Variable Universe Fuzzy Droop Control Based on a Novel Multi-Strategy Harris Hawk Optimization Algorithm for a Direct Current Microgrid with Hybrid Energy Storage

In the off-grid photovoltaic DC microgrid, traditional droop control encounters challenges in effectively adjusting the droop coefficient in response to varying power fluctuation frequencies, which can be influenced by factors such as line impedance. This paper introduces a novel Multi-strategy Harris Hawk Optimization Algorithm (MHHO) that integrates variable universe fuzzy control theory with droop control to develop an adaptive variable universe fuzzy droop control strategy. The algorithm employs Fuch mapping to evenly distribute the initial population across the solution space and incorporates logarithmic spiral and improved adaptive weight strategies during both the exploration and exploitation phases, enhancing its ability to escape local optima. A comparative analysis against five classical meta-heuristic algorithms on the CEC2017 benchmarks demonstrates the superior performance of the proposed algorithm. Ultimately, the adaptive variable universe fuzzy droop control based on MHHO dynamically optimizes the droop coefficient to mitigate the negative impact of internal system factors and achieve a balanced power distribution between the battery and super-capacitor in the DC microgrid. Through MATLAB/Simulink simulations, it is demonstrated that the proposed adaptive variable universe fuzzy droop control strategy based on MHHO can limit the fluctuation range of bus voltage within ±0.75%, enhance the robustness and stability of the system, and optimize the charge and discharge performance of the energy storage unit.

Investigating Conflict Management Styles and Emotional Intelligence of Unit Charge Nurses

Investigating Conflict Management Styles and Emotional Intelligence of Unit Charge Nurses

Unit prediction horizon [formula omitted] based model predictive control for the fuel cell based plug-in hybrid electric vehicle with rule-based energy management system

Plug-in hybrid electric vehicles (PHEVs) provide a good alternative in achieving better performance and in the reduction of harmful gas emissions. The hybrid energy storage system (HESS) and the integrated charging unit constitute the PHEV under consideration. To meet the load demands, the proposed HESS is a coupled system comprising a fuel cell, high energy density battery, and high-power density super-capacitor. On-board charging involves the utilization of a DC–DC buck converter and an uncontrolled rectifier and two buck-boost converters are utilized to facilitate a smooth transfer of energy. A rule-based supervisory controller has been implemented for different load conditions which takes into account the state of charge of energy sources and also the total power inflow of the power sources. A model predictive control (MPC) technique is implemented to ensure that PHEVs function smoothly in terms of regulation of DC bus voltage and tracking of current. Unit prediction horizon i.e. only one step ahead looking into the future is considered for the MPC to make it computationally less expensive. MPC is designed in such a way that its performance is close to our favorite linear controller which in our case is the H∞ controller. The inverse optimal control technique is used for determining the weight matrices of the cost function. The proposed controller has been simulated using MATLAB. Also, the performance comparison is made between the designed MPC and the non-linear control approach i.e. integral sliding mode control and integral backstepping-based control to show that it achieves comparable or superior performance to the non-linear controller. The real-time performance of H∞ based MPC is verified using controller hardware in the loop experimental setup.

Charge-Assisted Anion-π Interaction and Hydrogen Bonding Involving Alkylpyridinium Cations.

Competition and cooperation of charge-assisted anion-π interactions and hydrogen bonding were explored in the solid state and in solutions of 1-ethyl-4-carbomethoxypyridinium iodide, the compound utilized by Kosower to calculate solvent polarity Z-indices. X-ray structural analysis of this salt revealed multiple short contacts of iodide anions with hydrogen atoms and aromatic rings of pyridinium cations. Geometric characteristics, quantum theory of atoms in molecules (QTAIM), and noncovalent interaction (NCI) analysis of these contacts indicated comparable interaction energies of the anion-π and hydrogen bonding between iodide and pyridinium cation. 1H NMR (indicating the presence of the hydrogen-bonded complexes) and UV-vis measurements (which were consistent with the formation of anion-π associations) pointed out that both these supramolecular interactions also coexist in solutions. The comparable interaction energies (ΔE) of these modes were confirmed by the DFT computations. Also, while the variations of ΔE with the dielectric constant of the solvents for the complexes of iodide with the neutral π-acceptors were related to the increase of the effective radii of hydrogen- or anion-π bonded iodides, the changes in ΔE for the complexes with pyridinium followed interaction energies between two unit charges. However, the distinction of the bonding in hydrogen-bonded and anion-π complexes of iodide with pyridinium led to a switch of their relative energies with an increase of the polarity of the medium.

A dual-stage high-gain converter with dual inputs and dual outputs for electric vehicle charging

The DC-DC converter is an essential subsystem in electric vehicle (EV) chargers, and most converters depend on a single-input single-output structure, which can be costly when multiple charging units are needed. Additionally, these converters offer limited voltage gain, restricting charging configurations. This paper proposed a dual-stage high-gain converter that operates in a boost mode with reduced components, using an inductor, capacitor, and 2-diodes (LC2D) to provide high-gain output. The proposed Dual Inputs and Dual Outputs (DIDO) converter tied with Photovoltaic (PV) and constant DC acting as inputs and two different voltage levels EV chargers are serving as the output. The proposed converter operates at continuous conduction mode (CCM), achieving high efficiency and reliability with fewer losses. The proposed work was designed for 418V and 85V systems in MATLAB/Simulink, and the results were validated with hardware implementation. The proposed converter delivers high-gain output to the electric vehicle application with 92.2 % efficiency.

Progressive Loss of Sensitivity to Electrical Stimulation After Cochlear Implantation in X-Linked Incomplete Partition Type III Deafness.

Patients with X-linked incomplete partition type III (IP3) deafness treated with cochlear implants exhibit higher "Most Comfortable Loudness" (MCL) levels of stimulation and more electrode deactivation than patients with normal morphology. We endeavored to analyze the progression of the MCL levels and electrode deactivation over time and assess those factors that could have led to deactivation. Furthermore, we aimed to assess whether speech perception was affected by a progressive loss of neural contact. All 13 patients with the IP3 malformation in our clinical database were analyzed retrospectively with regard to impedance, stimulation levels, deactivated electrodes, and speech perception. A control group of patients with normal anatomy was included. MCL levels increased over time by 2.5 charge units (qu) per year, which was not seen in the control group. Electrode deactivation was more common in IP3 malformation, and it was estimated that 25% of electrodes would be deactivated by 15 years of age. Impedance was stable but higher in the study population. Speech perception was lower in IP3 malformation generally and was correlated to the number of deactivated electrodes. Patients diagnosed with IP3 malformation deafness may suffer a greater risk of cochlear implant discontinuation compared with those with normal anatomy. A progressive loss of sensitivity to electrical stimulation may indicate a form of neural degradation in the abnormal cochlea. With time, patients in this group, even with cochlear implant technology, may experience gradual deterioration of speech perception. This has clinical implications for the counseling of parents.

Multifunctional Bionic Periosteum with Ion Sustained-Release for Bone Regeneration.

In this study, a novel bionic periosteum (BP)-bioactive glass fiber membrane (BGFM) is designed. The introduction of magnesium ion (Mg2+) and zinc ion (Zn2+) change the phase separation during the electrospinning (ES) jet stretching process. The fiber's pore structure transitions from connected to closed pores, resulting in a decrease in the rapid release of metal ions while also improving degradation via reducing filling quality. Additionally, the introduction of magnesium (Mg) and zinc (Zn) lead to the formation of negative charged tetrahedral units (MgO4 2- and ZnO4 2-) in the glass network. These units effectively trap positive charged metal ions, further inhibiting ion release. In vitro experiments reveal that the deigned bionic periosteum regulates the polarization of macrophages toward M2 type, thereby establishing a conducive immune environment for osteogenic differentiation. Bioinformatics analysis indicate that BP enhanced bone repair via the JAK-STAT signaling pathway. The slow release of metal ions from the bionic periosteum can directly enhance osteogenic differentiation and vascularization, thereby accelerating bone regeneration. Finally, the bionic periosteum exhibits remarkable capabilities in angiogenesis and osteogenesis, demonstrating its potential for bone repair in a rat calvarial defect model.

Mechanistic Analysis of Reflective Cracking Potential in Electrified Pavement with Inductive Charging System.

Electrified pavements with inductive charging systems provide an innovative way of providing continuous wireless power transfer to electric vehicles (EVs). Electrified pavements have unique construction methods, resulting in different mechanical and thermodynamic characteristics from traditional pavements. This study aimed to investigate the mechanistic design of electrified pavements to mitigate thermal-induced reflective cracking due to the inclusion of concrete slabs with inductive charging units (CUs) under an asphalt surface layer. Finite element (FE) models were developed to analyze the temperature profiles, pavement responses, and crack potential in electrified pavements. The fatigue model and Paris' law were utilized to evaluate crack initiation and propagation for different pavement designs. Within the allowable range for sufficient wireless charging efficiency, increasing the surface layer thickness had a noticeable benefit on mitigating crack initiation and propagation. The results indicate that increasing the asphalt surface layer thickness by 20 mm can delay crack initiation and propagation, resulting in a two to threefold increase in the number of cycles needed to reach the same crack length. Reflective cracking can also be retarded by the optimized design of the charging unit. Increasing the concrete slab thickness from 100 mm to 180 mm resulted in an approximately 20% increase in the number of cycles to reach the same crack length. Reducing the slab width and length (shortening joint spacing) could also effectively reduce the reflective cracking potential, with the slab length having a more significant influence. These findings highlight the importance of balancing charging efficiency and structural durability in the design of electrified pavements.

S‐Tetrazine‐Bridged 2,2′‐Bipyrimidine as Superior Atom‐Economic Multi‐Charge Cathode Material for Lithium‐Ion Batteries

AbstractNitrogen‐containing heterocyclic molecules feature metal resource‐independence, flexible conjugation structure and fast charge storage kinetics, making them promising to be used as the electrode material in lithium‐ion batteries. However, an insufficiently high capacity (<400 mAh g−1) seriously threatens their practical application. Herein, a novel molecule, viz. 3,6‐bis(2‐pyrimidinyl)‐1,2,4,5‐tetrazine (DPmT), is developed by inserting an electron‐withdrawing π‐bridge unit of s‐tetrazine between two pyrimidine rings, in which a dense assembly of multiple active sites is realized. The DTmP exhibits a remarkable atom economy of 40 g (mol e)−1, which refers to the molecule mass per unit of charge transferred. The cathode material of DPmT yields a high capacity of 653 mAh g−1 and an energy density of 1188 Wh kg−1 at 50 mA g−1 at 70 °C. And 80% capacity retention is achieved after 500 cycles at 500 mA g−1, confirming its superior cyclability. Spectroscopy studies and theoretical calculations are performed to investigate the charge storage process. First, the C═N and N═N are claimed as plausible binding sites for the lithium ions. Second, the introduction of s‐tetrazine significantly enhances molecular planarity, thereby promoting charge delocalization and molecular stability. This work provides a novel strategy for designing atom‐economic multi‐charge electrode materials with high capacity.

Achieving Near-Infrared Phosphorescence Supramolecular Hydrogel Based on Amphiphilic Bromonaphthalimide Pyridinium Hierarchical Assembly.

Phosphorescent supramolecular hydrogels are currently a prevalent topic for their great promise in various photonic applications. Herein, an efficient near-infrared (NIR) phosphorescence supramolecular hydrogel is reported via the hierarchical assembly strategy in aqueous solution, which is fabricated from amphiphilic bromonaphthalimide pyridinium derivative (G), exfoliated Laponite (LP) nanosheets, and polymeric polyacrylamide (PAAm). Initially, G spontaneously self-aggregates into spherical nanoparticles covered with positively charged pyridinium units and emits single fluorescence at 410nm. Driven by electrostatic interactions with negatively charged nanosheets, the nanoparticles subsequently function as the cross-linked binders and coassemble with LP into supramolecular hydrogels with an engendered red room-temperature phosphorescence (RTP) up to 620nm. Benefiting from hydrogen-bonding interactions-mediated physical cross-linkage, the further introduction of PAAm not only significantly elevates the mechanical strength of the hydrogels showing fast self-healing capability, but also increases phosphorescence lifetime from 2.49to 4.20ms, especially generating phosphorescence at even higher temperature (τ 363 K = 2.46ms). Additionally, efficient RTP energy transfer occurs after doping a small amount of organic dye heptamethine cyanine (IR780) as an acceptor into hydrogels, resulting in a long-lived NIR emission at 823nm with a high donor/acceptor ratio, which is successfully applied for cell labeling in the NIR window.

Theoretical Design of New Grafted Molecules d-Glucosamine-Oxyresveratrol-Essential Amino Acids: DFT Evaluation of the Structure-Antioxidant Activity.

In the pursuit of innovative high-performance materials suitable for antioxidant applications, the density functional theory was employed to design a series of compounds derived from small biodegradable organic molecules. This study involved grafting the negatively charged unit d-glucosamine (GleN) and essential amino acids onto the 3 and 4' carbons of the backbone of trans-2,4,3',5'-tetrahydroxystilbene (trans-OXY), respectively. The aim was to prevent trans-OXY degradation into the cis region and enhance its electronic and antioxidant properties. Theoretical calculations using DFT/PW91/TZP in water revealed that the designed biomolecules (GleN-OXY-AA) outperformed both free OXY units and essential amino acids in terms of antioxidant efficacy, as indicated by the bond dissociation energy (BDE) findings. Notably, GleN-OXY-Ile and GleN-OXY-Trp compounds exhibited an average BDE of 66.355 kcal/mol, translating to 1.82 times the activity of t-OXY and 1.55 times the action of ascorbic acid (Vit C). AIM analysis demonstrated that the proposed biomaterials favored the formation of quasi-rings through intramolecular H···O hydrogen bonds, promoting π-electron delocalization and stabilization of radical, cationic, and anionic forms. Quantum calculations revealed the release of hydrogen atoms or electrons from sites of reduced electronegativity, visually identified by MEP maps and estimated by Hirshfeld atomic charges.

Electric vehicle supply equipment monitoring and early fault detection through autoencoders

This paper presents a novel approach to detecting anomalies in Electric Vehicle charging unit power profiles using a combination of Autoencoders with LSTM techniques. This study presents a robust methodology, combining the two Machine Learning techniques, for early fault estimation in a real-world case study. The proposed methodology offers significant advantages over existing methods by providing a more comprehensive analysis of anomalous trends. To validate the effectiveness of the proposed methodology, the authors tested it on real Electric Vehicles charging power curves provided by an Italian Distribution System Operator recorded on a historical database and compared the performances with the ones of a traditional anomaly detection technique. The results of the study, tested on Electric Vehicles Supply Equipment or charging stations, demonstrate that the proposed approach is highly effective in detecting anomalous trends in Electric Vehicles charging profiles.

Primordial monopoles, black holes and gravitational waves

We show how topologically stable superheavy magnetic monopoles and primordial black holes can be generated at observable levels by the waterfall field in hybrid inflation models based on grand unified theories. In SU(5) ×U(1) χ grand unification, the monopole mass is of order 4 × 1017 GeV, and it carries a single unit (2 π /e) of Dirac magnetic charge as well as screened color magnetic charge. The monopole density is partially diluted to an observable value, and accompanied with the production of primordial black holes with mass of order 1017–1019 g which may make up the entire dark matter in the universe. The tensor to scalar ratio r is predicted to be of order 10-5–10 -4 which should be testable in the next generation of CMB experiments such as CMB-S4 and LiteBIRD. The gravitational wave spectrum generated during the waterfall transition is also presented. The observed baryon asymmetry can be explained via leptogenesis.

Polyampholytes with Various Charge Distributions: Conformation States via Computer Simulation.

By means of molecular dynamics computer simulation, the conformational space of polyampholyte macromolecules with various distributions of the charged groups along the chain is studied. A coarse-grained model where each monomer unit of the chain is presented as a non-charged group in the backbone of the macromolecule connected with a charged side pendant is considered. A limiting case of fully charged chains in the isoelectric point is investigated. The oppositely charged monomer units are distributed in various patterns: regular alternating, multiblock, or random sequences. It is found that the chains with random unit distribution adopt much more compacted conformations than the chains with regular distributions with comparable block lengths. Calculating the chain size and its fluctuation along with the spatial density distribution, coil, and globular conformations are distinguished and arranged on the diagrams in terms of chain length, block length, and Bjerrum length.

Microscopic growth of pyridinium oxime based amphipathic on graphite: Effect of relative position of substituents

AbstractAmphipathic molecules with surfactant like properties have several applications ranging from healthcare to the chemical industry. Their ability to form thin films on surfaces with ordered and controllable patterns determines their applicability. Here, we report two pyridinium oxime‐based surfactants, which possess similar aggregation properties in solution, but exhibit substantially different assembly on highly oriented pyrolytic graphite (HOPG) surface. The two compounds are regioisomers with the oxime unit placed either in meta or para position of the pyridinium ring. While the para isomer assembled to anisotropic one‐dimensional (1D) islands and long rod‐like structures, the meta isomer formed two‐dimensional (2D) islands on the HOPG surface. This difference is rationalized through molecular level force‐field calculations that show anisotropy in the growth of the para isomer resulting from an effective overlap of the alkyl chains and oxime groups, which is distinctly not feasible in the assembly of the meta isomer. The assembly of these compounds is compared with another oxime‐containing compound of similar structure, but without the charged pyridinium unit. The charged unit seems to be crucial for the preferential formation of multilayer islands even at low coverage.

MBE growth of Ge1−x Sn x devices with intrinsic disorder

We discuss the electrical properties of molecular beam epitaxy (MBE) grown, modulation doped, Ge1−x Sn x quantum well devices. A consequence of the epitaxial growth process is that electronic disorder is introduced even in modulation doped quantum well structures and electrical transport properties that are characteristic of a high level of disorder are apparent. MBE growth of this material also results in the surface segregation of elemental β-Sn in the way that has been observed utilizing other epitaxial growth methods. A thermally activated, p-type mobility is a clear feature of the electrical properties with generally temperature independent hole densities ∼1012 cm−2 from the measured Hall effect and coming from the modulation doping. We present a discussion of Hall effect measurements in this disordered regime. The percolation carrier density in MBE modulation doped GeSn is in the region of ∼1 × 1012 cm−2 although Hall measurements in this regime are difficult to quantify when the resistivity >(h/e 2). In this notation h is Planck’s constant and e is the unit of charge. Conductivities (σ) as low as ∼0.028 × (e 2/h) × square can be measured in the four-contact ac configuration and the temperature dependence indicates a mobility edge in these p-type devices below ∼2 × 1012 cm−2. At lower temperatures (<∼1 K) the presence of a Coulomb gap can be determined using dc transport, constant voltage measurements where small ac current excitation is not available experimentally. This two-contact configuration can determine σ down to ∼10−6 × (e 2/h), deep into the localization regime, revealing a hopping conductivity dominated system. We discuss the relevance of these electrical properties for MBE grown GeSn devices.

DFTB Simulation of Charged Clusters Using Machine Learning Charge Inference.

We present a modification to self-consistent charge density functional-based tight binding (SCC-DFTB), which allows computation based on approximate atomic charges. We obtain these charges by means of a machine learning (ML) process that combines a Coulomb model with a neural network. This allows us to avoid the SCC cycles in the SCC-DFTB calculation while maintaining its accuracy. The main input of the model is the atomic positions characterized by a set of atom-centered symmetry functions. The charge inference from our ML algorithm is as close as 10-2 units of charge from the exact SCC solution. Our ML-DFTB approach provides a good approximation of the density matrix and of the energy and forces with only a single diagonalization. This is a significant computational saving with respect to the complete SCC algorithm, which allows us to investigate a bigger ensemble of atoms. We show the quality of our approach in the case of charged silicon carbide (SiC) clusters. The ML-DFTB potential energy surface (PES) mimics the SCC-DFTB PES rather well, despite its simplicity. This allows us to obtain the same geometric structure ordering with respect to energy for small clusters. The dissociation barriers for ion emission are well-reproduced, which opens the way to investigating ion field emission and charged cluster stability. The ML-DFTB approach is obviously not limited to charged clusters or SiC materials. It opens a new route to investigate larger clusters than those investigated by standard SCC-DFTB, as well as surface and solid-state chemistry at the atomic level.

TOPOLOGY OF GALVANIC ISOLATED BATTERY CHARGING UNIT WITH POWER FACTOR CORRECTION

The present study investigates topology for battery charging units (BCU) with simple design and power factor correction. It has a galvanic isolation between the grid and the battery, which is one of the law and standard requirements. The impulse transformer ensures galvanic isolation, which makes the topology suitable for onboard electric vehicles (EV) charging units (OBC). The study also presents a simulation model a simulation model with the help of which a simulation is conducted and a result is obtained.