Unit Charge Research Articles

Superior electrochemical performance and reduced heat generation in 3D printed vs. 2D tape-casted NMC622 electrodes

This study compares the charge storage mechanisms, thermodynamics behavior, ion transport, and heat generation in NMC622 electrodes fabricated using a novel 3D printing process or the conventional 2D tape casting process. First, potentiometric entropy measurements revealed that the charge storage mechanisms for both types of electrodes consisted of lithium deintercalation in a homogeneous solid solution of NMC622 followed by a transition from a hexagonal (H1) phase to another hexagonal (H2) phase through a monoclinic (M) phase. Both types of electrodes had similar thermodynamics behavior with overlapping entropic potential profiles. Furthermore, operando isothermal calorimetry at high C-rates indicated that the 3D printed electrodes featured larger specific capacity and better rate performance than the 2D tape-casted electrodes. The better performance of 3D printed electrodes was attributed to their larger electrode/electrolyte interfacial surface area and electrical conductivity as well as their faster lithium ion transport. As a result, the instantaneous heat generation rates were smaller in 3D printed electrodes than in 2D tape-casted electrodes, thus resulting in lower overall specific electrical energy and thermal energy dissipation per unit charge stored. Overall, additive manufacturing techniques offer great potential in producing electrodes with superior electrochemical performance and reduced heat generation for fast charging batteries.

Encapsulation of Vecuronium and Rocuronium by Sugammadex Investigated by Surface-Enhanced Raman Spectroscopy.

Aiming toward a novel, noninvasive technique, with a real-time potential application in the monitoring of the complexation of steroidal neuromuscular blocker drugs Vecuronium (Vec) and Rocuronium (Roc) with sugammadex (SDX, medication for the reversal of neuromuscular blockade induced by Vec or Roc in general anesthesia), we developed proof-of-principle methodology based on surface-enhanced Raman spectroscopy (SERS). Silver nanoparticles prepared by the reduction of silver ions with hydroxylamine hydrochloride were used as SERS-active substrates, additionally aggregated with calcium nitrate as needed. The Vec and Roc SERS spectra were obtained within the biorelevant 5 × 10-7-1 × 10-4 M range, as well as the SERS of SDX, though the latter was observed only in the presence of the aggregating agent. SDX/drug complexes at a 1/1 molar ratio revealed significant spectral changes in the vibrational bands of the SDX glucose rings and the drug steroid rings, implying that the insertion of Vec and Roc molecules into the SDX cavity was not only driven by attractive electrostatic interactions between the positively charged cyclic unit of the drug and the negative carboxylate groups of cyclodextrin but also supported by hydrophobic interactions between the host cyclodextrin and the guest drug molecule. The observed changes in SERS signals are applicable in biorelevant conditions and support further studies of SDX/drug complexes in vivo.

Development of a 300 kV/3kHz nanosecond pulse generator using semiconductor opening switches.

In this paper, we present the development of a nanosecond pulse generator utilizing semiconductor opening switches (SOS), designed to deliver high voltage and operate at a high repetitive frequency. The pulse generator comprises three main components: a primary charging unit, a magnetic pulse compression unit, and an SOS magnification unit. To ensure stable operation of the high-power charging unit at high repetitive frequencies, a rectifying resonant charging and energy recovery circuit are implemented, providing a 1kV charging voltage at a 3kHz repetition rate. The three-stage magnetic pulse compression is designed to reduce the pulse width from tens of microseconds to tens of nanoseconds, where self-demagnetization could be completed during repetitive frequency operation. To achieve an output voltage of 300kV, multiple SOS switches are employed in a series. The developed pulse generator achieves a final output of 300kV with a 3kHz repetitive frequency under a load of 2 kΩ. Furthermore, the effects of multiple factors on the output performance are characterized by both simulation and measurement for a comprehensive analysis.

Plasma constraints on the millicharged dark matter

Dark matter particles were suggested to have an electric charge smaller than the elementary charge unit e. The behavior of such a medium is similar to a collisionless plasma. In this paper, we set new stringent constraints on the charge and mass of the millicharged dark matter particle based on observational data on the Bullet X-ray Cluster.

Electrostatic Control of Electronic Structure in Modular Inorganic Crystals.

The rules that govern structure and bonding, established for elemental solids and simple compounds, are challenging to apply to more complex crystals formed of polyatomic building blocks, such as layered or framework materials. Whether these modular building blocks are electrically neutral or charged influences the physical properties of the resulting crystal. Despite the prevalence of alternating charged units, their effects on the electronic structure remain unclear. We demonstrate how the distribution of charged building blocks, driven by differences in the electrostatic potential, governs the electronic band energies formed in layered crystals. This coarse-grained model predicts the spatially separated valence and conduction band edges observed in the metal-oxyhalide Ba2Bi3Nb2O11Cl and explains observed property trends in the Sillén-Aurivillius crystal system. Moreover, the general nature of the model allows for extension to other modular structure types, illustrated for Sillén and Ruddlesden-Popper layered compounds, and can support the rational design of electronic properties in diverse materials.

Interaction between the Polyelectrolytes Unfractionated Heparin and Universal Heparin Reversal Agents.

The interaction of unfractionated heparin (UFH) with universal heparin reversal agent 7 (UHRA-7) is investigated. UHRA-7 is composed of a hyperbranched polyglycerol core onto which an array of methylated tris(2-aminoethylamine) (Me-TREN) charged groups is grafted, which in turn are shielded with a layer of small chain poly(ethylene glycol) methyl ether (mPEG) chains. This system has previously been shown to be biocompatible and to be effective at neutralizing heparin. The binding constant Kb was determined from isothermal titration calorimetry experiments, at temperatures ranging from 278 to 323 K and salt concentrations ranging from 0.06 to 0.20 M NaCl. The data were analyzed in terms of a number of different theoretical models to determine the contribution of counterion release and water release to driving the interaction between UFH and UHRA-7. With the support of NMR and molecular dynamics simulation data, a model of the interaction between UFH and UHRA-7 is proposed. The binding of heparin and universal heparin reversal agent 7 is mainly due to charge-charge interactions between the negatively charged units on UFH with positively charged Me-TREN and mPEG chains.

Spin-orbit interaction-mediated measurement of surface chirality.

The spin-orbit (σ - l) interaction in a focused-reflected beam of light results in spatially nonuniform polarization in the beam cross section due to the superposition of orthogonal field components and polarization-dependent interface reflection coefficients. Polarization filtering the output beam leads to an interchangeable transformation of l=∓2 charge vortex into two (∓) unit charge vortices, for σ = ±1 circular polarization of the input Gaussian beam. This transformation follows a trajectory, named optical vortex trajectory, that depends on the input beam's σ and hence the l and reflecting surface characteristics. The vortex trajectory is used here to quantify both the sign and the magnitude of the chiral parameter of a quartz crystal. The Jones matrix-based simulation anticipates the chirality-dependent vortex trajectory that matches with experimental measurements.

Effect of doping on suppression of Coulomb explosion in dicationic noble gas clusters

Dicationic noble gas clusters undergo disintegration due to the repulsive force between charged ions, known as Coulomb explosion (CE). However, beyond a certain size limit, the attractive forces suppress the Coulombic repulsion, enabling the clusters to stabilise. We explored the potential energy surface (PES), which incorporates electrostatic interactions (including Coulombic and induced dipole) and the Lennard-Jones potential, using parallel tempering to determine the cutoff limit for suppressing Coulomb explosions (CE) in both pure and doped noble gas clusters. The influence of both homogeneous (i.e. both charge on two bigger atoms) and heterogeneous charge distributions (i.e. two units of charge being centred on one large and one smaller atom) is evaluated for doping applications. The simulations reveal that single ion ejection is the major dissociation pathway below the cutoff limit. Additionally, the cutoff limit smoothly decreases with gradual doping of heavier atoms in both types of charge distribution.

The Relationship Between eSRTs and Upper Stimulation Levels in a Large Cohort of Adult Cochlear Implant Recipients.

To compare electrically evoked stapedial reflex thresholds (eSRTs) measured at 1 month post-activation to upper stimulation levels used for programming adult cochlear implant (CI) recipients over time in a large clinical population. Review of prospectively collected clinical database. Large CI program at an academic medical center. Postlingually deafened adult CI recipients (n = 439). eSRTs recorded in the medical record and upper stimulation levels derived from the programming software at 1 and 6 months post-activation. The correlation between eSRTs and upper stimulation levels was strong for all three manufacturers (r = 0.80-0.86). On average, upper stimulation levels were set 15.4 clinical levels below eSRT for Cochlear using a pulse width of 25 microseconds, 13.4 clinical levels below eSRT for Cochlear using a pulse width of 37 microseconds, 11.3 clinical units below eSRT for Advanced Bionics, and 0.1 charge unit above eSRT for MED-EL. eSRTs were found to be elicited at similar levels for different electrodes/frequencies across the array. After upper stimulation levels were set based on eSRT at 1 month post-activation, there was no significant change in upper stimulation levels between 1 and 6 months post-activation. eSRTs and upper stimulation levels are highly correlated. Average differences between eSRTs and upper stimulation levels reported herein can be used to guide programming in the clinic. Further, when eSRTs are used to program upper stimulation levels, upper stimulation levels should be relatively similar across channels and stable over time.

Bridging cultural gaps in end-of-life care: the experiences of international charge nurses in Saudi Arabia

IntroductionThis qualitative study explores the experiences and perspectives of international intensive care unit charge nurses providing end-of-life care to Muslim patients in Saudi Arabia. It examines how these nurses navigate the complexities of delivering culturally sensitive care, particularly regarding Islamic beliefs and practices. The study also investigates the challenges encountered by international nurses due to differing healthcare expectations between themselves and patients’ families, highlighting the interplay between cultural sensitivity and effective end-of-life care in this unique context.MethodA qualitative descriptive design was employed, using semi-structured interviews to gather data from eight international ICU charge nurses working in a tertiary hospital in Saudi Arabia. Thematic analysis was used to analyze the interview transcripts.ResultsThis qualitative study explored the experiences of international ICU charge nurses in Saudi Arabia regarding culturally sensitive end-of-life care within Islamic traditions. Analysis revealed nine key themes and 31 subthemes reflecting the multifaceted nature of this sensitive domain. These themes encompassed intercultural anxieties, emotional burdens on families and nurses, the importance of bridging cultural divides, advocating for change in end-of-life care practices, and honoring diverse spiritual needs. Key findings emphasized the significance of family presence, honoring faith in the absence of family, and ensuring peaceful and compassionate passings, highlighting nurses’ commitment to holistic, patient-centered care that respects both cultural and individual beliefs..ConclusionThis study provides valuable insights into the cultural nuances of end-of-life care in Saudi Arabia. The findings underscore the importance of culturally sensitive practices that respect Islamic beliefs, prioritize family involvement, and address the holistic needs of patients and their families.ImplicationsThis study underscores the need for culturally sensitive communication training for healthcare providers working with diverse patient populations. Hospitals and healthcare institutions should prioritize educational initiatives that equip staff with the skills to engage in open dialogues about death and dying, navigate cultural differences in end-of-life preferences, and address the use of traditional healing practices. By fostering greater cultural understanding and communication competency, healthcare systems can better support both patients and families in navigating the complexities of end-of-life care.

SILAR-Deposited Metal Chalcogenides Promoting Polysulfide Conversion in Sulfur-Based Redox Flow Batteries

Rechargeable flow batteries (RFBs) are leading the way as possible candidates for low-cost, long-duration energy storage applications (>10 hours), due to their unique capability to decouple power and energy. The state-of-the-art in RFB technologies is represented by the most advanced all-vanadium chemistry (VRFB), but the limited availability and cost of the raw materials hinder their diffusion.The main objective of this work is to explore innovative electrolytes for next-generation cost-effective redox flow batteries. Sulfur can fulfill the requirement of high specific capacity (1672 mAhg-1), has the lowest cost per unit charge among reactive materials (52 Ah $-1) [1], however the well-known sluggish kinetics of sulfur-based electrolytes require the use of electrocatalysts to enhance the power output. Cobalt sulfide (CoS2) is the most used catalyst for polysulfide conversion but concerns about cobalt avaibility and price volatility make it a critical material to replenish [2].SILAR technique is a simple and scalable method to grow semiconducting thin films and in this work is used to graft metal chalcogenides on carbon felt fibres as polysulfide catalytic materials [3], [4].In this study, to avoid degradation issues related to the most commonly used highly alkaline polysulfide solutions ([OH-] > 3M), sulfur was dissolved in KCl supporting electrolytes. To demonstrate the operability of the proposed polysulfide anolyte, a custom made electrochemical cell was used to independently investigate the electrochemical activity and stability of the electrode under real conditions. The design of the cell allows the characterization of the anolyte and catalyst directly on the carbon felt, both under static and flowing conditions, thereby avoiding characterization on usually used ideal and unrepresentative substrates of the system, such as glassy carbon electrodes.The electrochemical activity of the SILAR-deposited CuS catalyst is studied at different loadings to determine the correlation between the increase in electrochemical activity with the amount of catalyst deposited. Scanning electron microscope (SEM) images were used to demonstrate the morphology and uniformity of deposition, XRD and EDS distribution maps to evaluate phase and elemental distribution.The electrolyte stability and catalyst degradation in time were investigated through charge/discharge tests of a polysulfide/ferricyanide RFB cell. Overall, the study provides significant insights into the development of high-performance aqueous polysulfide-based batteries. Based on our findings, sulfur has great potential as a cost-effective anolyte candidate for integration into redox flow batteries.

Chiral Supramolecular Proton Conductors: Harnessing Highly Charged Zirconium-Amino Acid Oxo-Clusters.

Incorporation of amino acid capping molecules (alanine (Ala), methionine (Met), phenylalanine (Phe), tryptophan (Trp), tyrosine (Tyr), and valine (Val)) in their zwitterionic form into archetypal [Zr6(μ3-O)4(μ3-OH)4]12+ clusters creates supramolecular frameworks in which the assembly of these highly charged discrete units with chloride counterions provides a unique combination of porosity, chirality, and proton conductivity. The supramolecular frameworks assembled from these cluster entities (i.e., ZrAla, ZrMet, ZrPhe, ZrTrp, ZrTyr, and ZrVal) are based on the counterbalancing of the cationic hexanuclear entities by chloride anions. The resulting structures provide porous structures (except ZrVal) with variability of chemical and structural stability based on their supramolecular interactions. Among these compounds, ZrPhe and ZrVal remain stable due to the presence of a double chelation-like interaction involving four hydrogen bonds formed between a chloride anion, two ammonium groups, and two coordinated water molecules from two adjacent hexanuclear units. The presence of multiple acidic proton positions and strong hydrogen-bond donor/acceptor groups on the water channels gives rise to easy proton conduction pathways within the structures. In fact, ZrPhe and ZrVal, together with ZrTyr, exhibit high proton conductivity values with varying dependencies on the atmospheric humidity. Finally, the correlation between proton conduction and porosity is discussed.

Pressure and Isothermal Compressibility of Asymmetric Complex Plasmas in the Poisson–Boltzmann Plus Hole Approximation

ABSTRACTWe consider a two‐component asymmetric complex plasma of finite‐size macroions with charges () and point oppositely charged microions with unit charges. System pressure is calculated within the framework of the Poisson–Boltzmann plus hole approximation by obtaining the Coulomb nonideal parts of interaction energy and Helmholtz free energy. It is shown that both the pressure and plasma isothermal compressibility are positive over the entire range of macroion concentrations. We compared pressure and isothermal compressibility in linearized approximations and in the Poisson–Boltzmann plus hole approximation where the nonlinear screening effect is taken into account and showed a significant difference for some macroions concentrations.

Techno economics and energy dynamics of a solar powered smart charging infrastructure for electric vehicles with advanced IoT based monitoring and RFID based security

The widespread adoption of electrical vehicles (EVs) has led to an increased demand for charging stations which required an adequate charging infrastructure. However, this challenge brings substantial financial and ecological implications for the power grid and other major stakeholders such as EV users, system operators and policymakers. To resolve this issue, this work proposes a smart EV charging infrastructure that provides 1) effective load management of EVs, 2) real-time monitoring of charging slots at a charging station, 3) smart security system, and 4) integration of renewable energy resources (RERs) into charging stations. This is achieved by setting out how to incorporate photovoltaic (PV) system into charging station infrastructure while suggesting effective EV load management with optimal energy utilization and minimal energy costs. Also, the annual power production of PV systems and power sharing between different power resources has been investigated to enable effective decisions about EV scheduling. The proposed infrastructure also offers an internet-of-things (IoT)-based monitoring of fast/slow charging units with real-time slot tracking to the users and charging station operators. The security aspect of the charging station is covered by a sensor-driven radio frequency identification (RFID) system. Experimental results that the proposed system generates 1,055,326 kWh/year, reducing grid reliance by 50% (to 335,775 kWh) and lowering CO2 emissions from 425,326 kg to 212,210 kg. Moreover, energy costs drop from $0.30 to $0.13 per kWh and 270,567 kWh/year energy is sold back to the grid. The proposed system yields a net present revenue of $1,020,000 which demonstrates significant economic and environmental benefits.

Thermo- and light responsive microgels for efficient brackish and seawater forward osmosis desalination

Forward osmosis desalination presents a promising solution to address water shortages in areas near brackish or seawater sources. This study investigates the use of thermo-responsive poly(N-isopropyl acrylamide-rand‑sodium acrylate) microgels as innovative draw agents for forward osmosis desalination. The drawing ability and responsiveness of these microgels are significantly influenced by the charged comonomer content. Unlike bulk hydrogels, these microgels, owing to their core-shell morphology, maintain thermo-responsivity even at higher comonomer content. Incorporating graphene oxide as a light absorber allows for partial heating, required to reach the transition temperature, to be obtained using UV light radiation. In forward osmosis, microgels can be used either in a dried state or as a concentrated aqueous dispersion. A sample with 25 mol% charged units achieved a balance between water flux and responsiveness. It reached fluxes of 2.84, 4.79 and 4.39 L·m−2·h−1 for the dried state, 40 wt% and 20 wt% dispersions, respectively, when tested with 5 g·L−1 brackish water. Furthermore, a 40 wt% dispersion drew 35 g·L−1 seawater at a flux of 1.36 L·m−2·h−1. This sample, which contains graphene oxide, exhibited a volume phase transition temperature at 41 °C that can be achieved through UV light radiation or natural sunlight exposure. Water separation from the microgels was accomplished through filtration under UV-light radiation with a power of 4 kW·m−2, at 2–4 bar pressure, with a microfiltration membrane and a flux of 36 L·m−2·h−1. These findings highlight the potential of these thermo-responsive microgels for efficient forward osmosis desalination.

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.

Experimentally measured assembly indices are required to determine the threshold for life.

Assembly theory (AT) aims to distinguish living from non-living systems by explaining and quantifying selection and evolution. The theory proposes that the degree of assembly depends on the number of complex objects, with complexity measured using a combination of the object's assembly index (AI) and its abundance. We previously provided experimental evidence supporting AT's predictive power, finding that abiotic systems do not randomly produce organic molecules with an AI greater than approximately 15 in detectable amounts. Hazen et al. (Hazen et al. 2024 J. R. Soc. Interface 21, 20230632. (doi:10.1098/rsif.2023.0632)) proposed inorganic molecules that theoretically have AIs greater than 15, suggesting similar complexity to biological molecules. However, our AIs are experimentally measured for organic, covalently bonded molecules, whereas Hazen's are theoretical, derived from crystal structures of charged units that are not isolable in solution. This distinction underscores the challenge in experimentally validating theoretical AIs.

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