Number Of Charges Research Articles

Phosphorus/Sulfur-Enriched Reduced Graphene Oxide Papers Obtained from Recycled Graphite: Solid-State NMR Characterization and Electrochemical Performance for Energy Storage

The reduction of graphene oxide (GO) by means of thermal and/or chemical treatments leads to the production of reduced graphene oxide (rGO)—a material with improved electrical conductivity and considered a viable and low-cost alternative to pure graphene in several applications, including the production of supercapacitor electrodes. In the present work, GO was prepared by the oxidation of graphite recycled from spent Li-ion batteries using mixtures of sulfuric and phosphoric acids (with different H2SO4/H3PO4 ratios), leading to the production of materials with significant S and P contents. These materials were then thermally reduced, resulting in rGO papers that were investigated by solid-state 13C and 31P nuclear magnetic resonance, along with other methods. The electrochemical properties of the produced rGO papers were evaluated, including the recording of cyclic voltammetry and galvanostatic charge–discharge curves, besides electrochemical impedance spectroscopy analyses. The samples obtained by thermal reduction at 150 °C exhibited good rate capability at high current density and high capacitance retention after a large number of charge–discharge cycles. The results evidenced a strong relationship between the electrochemical properties of the produced materials and their chemical and structural features, especially for the samples containing both S and P elements. The methods described in this work represent, then, a facile and low-cost alternative for the production of rGO papers using graphite recycled from spent batteries, with promising applications as supercapacitor electrodes.

Identification of endogenous carbonyl steroids in human serum by chemical derivatization, hydrogen/deuterium exchange mass spectrometry and the quantitative structure-retention relationship

Steroids are tetracyclic aliphatic compounds, and most of them contain carbonyl groups. The disordered homeostasis of steroids is closely related to the occurrence and progression of various diseases. Due to high structural similarity, low concentrations in vivo, poor ionization efficiency, and interference from endogenous substances, it is very challenging to comprehensively and unambiguously identify endogenous steroids in biological matrix. Herein, an integrated strategy was developed for the characterization of endogenous steroids in serum based on chemical derivatization, ultra-performance liquid chromatography quadrupole Exactive mass spectrometry (UPLC-Q-Exactive-MS/MS), hydrogen/deuterium (H/D) exchange, and a quantitative structure-retention relationship (QSRR) model. To enhance the mass spectrometry (MS) response of carbonyl steroids, the ketonic carbonyl group was derivatized by Girard T (GT). Firstly, the fragmentation rules of derivatized carbonyl steroid standards by GT were summarized. Then, carbonyl steroids in serum were derivatized by GT and identified based on the fragmentation rules or by comparing retention time and MS/MS spectra with those of standards. H/D exchange MS was utilized to distinguish derivatized steroid isomers for the first time. Finally, a QSRR model was constructed to predict the retention time of the unknown steroid derivatives. With this strategy, 93 carbonyl steroids were identified from human serum, and 30 of them were determined to be dicarbonyl steroids by the charge number of characteristic ions and the number of exchangeable hrdrogen or comparing with standards. The QSRR model built by the machine learning algorithms has an excellent regression correlation, thus the accurate structures of 14 carbonyl steroids were determined, among which three steroids were reported for the first time in human serum. This study provides a new analytical method for the comprehensive and reliable identification of carbonyl steroids in biological matrix.

Focusing pattern of the Laguerre-Gaussian beam with polarization mixing helical-conical phase modulation.

This paper focuses on the focusing pattern of the Laguerre-Gaussian (LG) beam with polarization mixing helical-conical phase modulation, which is based on the vector diffraction theory. The results show that the topological charge number l can sensitively control the intensity of the intensity peaks. The focal spot will split along the optical axis under different polarization parameters P. When l=1, the spot position and the peak intensity can be modulated by changing the polarization parameter P. The truncation parameter β makes the focusing spot form an optical trap. By adjusting the eccentricity parameter K, the opening direction of the optical trap can be well controlled. These results may be helpful in optical applications such as optical manipulation, optical focusing, and optical information transmission.

Unraveling the cation adsorption of geopolymer binder: A molecular dynamics study

Geopolymers play a significant role in remediation of heavy metal contamination and are attracting increasing interests. Sodium aluminosilicate hydrate (NASH) is the prime hydration substance of geopolymers which exhibits excellent adsorption capacity, however, the mechanism of metal cation adsorption at the NASH interface remains unclear. In this study, the adsorption behavior of cations at the NASH interface was investigated in depth, and the effects of Si/Al ratios, ion concentration and ion type on adsorption behavior were also analyzed. Furthermore, three Si/Al ratio models of NASH gel were modified and developed by molecular dynamics simulation, and validated by experiments. The result showed that electrostatic attraction and ion exchange played the major role in adsorbing three cations on the surface of NASH gel. For cations with the same charge number, ionic radius was inversely proportional to the cation exchange and adsorption capacity. Cations with lower ionic potential, among those with different charge numbers, were easier to be adsorbed onto the NASH surface. Therefore, the adsorption capacity of NASH for the three adsorbents was in the order of Na+ > Cs+ > Pb2+. The adsorption capacity of NASH gel for cations increased with the increasing of Al/Si and decreased with the increasing of cation concentration, which was attributed to the increased electrostatic attraction on the NASH surface and the limited number of adsorption sites. The derived microstructure and dynamics information are beneficial for profoundly understanding the adsorption mechanisms of geopolymers on cations.

Comparison of reliability and economic feasibility for the three configurations of multiple battery charging systems

AbstractMultiple battery charging systems can be configured with various combinations of ac‐dc and dc‐dc converters. This paper reviews the reliability and economy of three representative configurations of multi‐battery charging systems. Existing PSA (part stress analysis) can analyse the failure rate considering the environmental factors for the type of parts, the number of parts, the connection state of parts and the voltage and current stress of parts. However, since it does not reflect the system's operating characteristics, the Fault‐tree analysis (FTA) method based on the fault tree is used. Still, it cannot be analysed considering the operational risk of the converter according to various load conditions. Therefore, in this study, by defining a failure according to the minimum and maximum load of the multiple battery charging systems and designing a separate fault tree, the converter operation characteristics were considered by reflecting the number of battery charges, the characteristics according to SOC (state of charge) and the redundancy effect that appears when cyclic charging is applied. Through the new enhanced FTA method, the multiple battery charging systems (Type 1) to which sequential charging is applied are quantitatively proven advantageous in terms of reliability and economy.

Possibility of antiquark nuggets detection using meteor searching radars

Within the quark nugget model, dark matter particles may be represented by compact composite objects composed of a large number of quarks or antiquarks. Due to strong interaction with visible matter, antiquark nuggets should manifest themselves in the form of rare atmospheric events on the Earth. They may produce ionized trails in the atmosphere similar to the meteor trails. There are, however, several features which should allow one to distinguish antiquark nugget trails from meteor ones. We study the properties of ionized trails from antiquark nuggets in the air and show that they may be registered by standard meteor radar detectors. Non-observation of such trails pushes up the mean baryon charge number in the quark nugget model, $|B|>4\times 10^{27}$.

Molecular orientation and optimization of membrane dyes based on conjugated oligoelectrolytes

Conjugated oligoelectrolytes (COEs) are amphiphilic, fluorogenic molecules that spontaneously associate with lipid bilayer membranes and are gaining attention as molecular reporters, particularly for exosome detection by flow cytometry. Questions nonetheless remain on how to best design COEs for optimal performance and on the geometry of lipid bilayer intercalation. In response, we designed a series of oligo-phenylenevinylene COEs with varying lengths and numbers of charged groups to address these uncertainties. Examination of the organization within lipid bilayers through polarized fluorescence microscopy shows that the optical transition moments are perpendicular to the bilayer plane, with the conjugated segment flanked by hydrophobic phospholipid tails. COEs initially form a disorganized layer on the vesicle periphery, reflecting electrostatic association before intercalation. Uptake experiments show that longer dimensions and increased numbers of charges allow for a higher degree of cellular association. Both shorter core length and increased number of charges accelerate the rate needed to achieve emission saturation.

Effects of incorporating Mn into goethite on adsorption of dissolved organic matter and potentially toxic elements in soil: Isotherms, kinetics, and mechanisms

Goethite is ubiquitous in the environment and plays key role in preserving dissolved organic matter (DOM) and deactivating potentially toxic elements (PTEs) by adsorbing DOM and PTEs. Various non-Fe metals are usually incorporated into natural goethite, substituting Fe in the goethite structure, which dramatically influence the physico-chemical properties and adsorption behavior of the goethite. In the present study, adsorption of DOM and Pb(II) on Mn-substituted goethite samples was investigated. The results displayed that the specific surface area (SSA) of mineral samples increased by 67.6% as the incorporation of Mn for Fe, from 25.71 m2 g−1 for pure goethite to 43.09 m2 g−1for Mn-goethite. Besides, the Mn substitution caused more hydroxyl groups and relatively fewer positive charges on mineral surface, and Mn in the Mn-goethite samples was predominantly present as Mn(III). The amount of DOM adsorbed to per unit mass of goethite was increased as Mn content increased, which was attributed to Mn incorporation increasing the SSA of mineral samples. However, the SSA-normalized absorption capacity for goethite to DOM was decreased by Mn because Mn substitution decreased the number of positive charges of mineral samples, which weakened the electrostatic attraction between DOM and the minerals. The amount of Pb(II) adsorbed to per unit mass of goethite was increased by Mn substitution, and the amount of Pb(II) adsorbed to per unit SSA of goethite increased as the amount of Mn substitution increased, indicating that the increased capacity for adsorbing Pb was not only caused by the SSA increasing but also by there were more surface hydroxyl groups on the Mn-goethite than pure goethite and Pb(II) preferentially adsorbed to Mn sites on the Mn-goethite. The present study results showed that Mn-goethite could be used to sequester DOM and remediate soil contaminated with PTEs because Mn-goethite has a high adsorption capacity and is environmentally benign.

Ideal unconventional charge-2 Dirac fermions in an ultralightweight chiral crystal

When topology meets chirality, it is of great interest to search for possible topological properties in chiral crystals, thereby achieving the effect of making $1+1$ greater than 2. Here, we accomplish a complete list of topological charge-2 (C-2) Dirac fermions based on 65 S\"ohncke space groups. Such emergent fermions occurring in chiral crystals enjoy a higher topological charge number and exhibit more unique characteristics compared to C-0 cases, including multiple Fermi arcs extending to most of the Brillouin zone. For material realization, we propose that an ultralightweight chiral crystal ${\mathrm{N}}_{4}\mathrm{Cl}$ is a high-quality C-2 Dirac semimetal, where the seductive nodal points reside at the Fermi level and exhibit a large linear energy range to overcome the interruption of irrelevant bands. More interestingly, the doubly degenerate Landau levels are described by a Kramers-like degeneracy in such a C-2 Dirac fermion, featuring a doubly degenerate zero mode. Furthermore, the topological phase transitions from Dirac to Weyl states of ${\mathrm{N}}_{4}\mathrm{Cl}$ can be manipulated by applying shear strains. These fascinating findings will certainly evoke continued exploration of unconventional Dirac semimetals, in turn leading to extensive application prospects and uncommon insights.

Accelerated thermal decomposition of ammonium perchlorate by electron transfer from dinuclear rare-earth EMOFs

Energetic metal-organic framework materials (EMOFs) are a class of energetic complexes formed by constructing energetic organic compounds with metal ions, which have garnered considerable attention due to their potential catalytic role in promoting the thermal decomposition of ammonium perchlorate (AP). However, how to improve the catalytic effect is still long-standing issue for EMOFs. Based on the electron transfer between rare earth metal ions with positive holes in the d, f-orbital and ammonium perchlorate ions, three rare earth EMOFs (La2(tza)3(H2O)6·4H2O, Ce2(tza)3(H2O)6·3H2O, and Nd2(tza)3(H2O)6·4H2O) were synthesized by solution evaporation method and their effects on the thermal decomposition of AP were investigated. The three EMOFs are binuclear isomorphic and form thermally stable (Tdet > 630.0 K) 3D structures through extensive hydrogen bonds. In addition, the introduction of lanthanide metals can enhance the electron transfer ability of EMOFs and promote the electron transfer of AP/EMOFs mixtures, which is beneficial to modulate the catalytic performance of EMOFs for the AP thermal decomposition. The addition of the three EMOFs caused the high-temperature decomposition peak of AP towards the low-temperature. Meanwhile, the temperature of the high-temperature decomposition peak was advanced by 46.8 K ∼ 59.8 K, and the activation energy (Ea) was reduced by 85.02 ∼ 117.71 kJ/mol, which could significantly improve the thermal decomposition performance of AP. Most importantly, compared to the other two EMOFs, the cation in Nd2(tza)3(H2O)6·4H2O has the highest effective nuclear charge number in the f orbital and strongest electron transfer ability, which can reduce the Ea of AP to 96.85 kJ/mol. Overall, the strategy of construction EMOFs by increase the electron transfer ability can provide guidance for the exploration of novel and efficient energetic catalysts.

Technical note: Simplified approaches to estimate the output of particle mass analyzers paired with unipolar chargers

Particle mass analyzers (PMAs) classify particles by their mass-to-charge ratio. PMAs are often paired with bipolar chargers, which produce charge distributions that consist of positively-, negatively, and neutrally-charged particles, which greatly limits the transmission efficiency of PMAs and allows small, uncharged particles to be classified erroneously. These limitations provide an opportunity for unipolar chargers, which impart several charges per particle. However, the PMA setpoint (mass-to-charge ratio) loses physical meaning when the average number of charges per particle mass is unknown. The average charge of the PMA classified particles can be inferred from downstream size distribution measurements or by running detailed models. However, downstream measurements are often practically infeasible and detailed models require knowledge of the unclassified aerosol size and density. These challenges motivate a need for simplified approaches. Using simulations, we show that the unipolar charger-PMA average charge can be estimated to within ±20% for a reasonable range of parameters for typical aerosol scenarios. The most significant uncertainties behind the simplified approach are related to particle morphology (e.g., fractal versus spheroidal particles). Our simplified approach relies on the derivation of an empirical power-law relationship between the particle average charge and particle diameter, which is consistent with several previous experimental studies and existing models. The approaches described in this work improve the capabilities of unipolar charger-PMA systems to classify a known average mass (rather than a known mass-to-charge ratio) which is valuable for characterizing and calibrating the response of optical and mass instruments.

Solitary wave solution of (3+1)-dimensional cylindrical Kadomstev–Petviashvili equation in warm opposite polarity dusty plasma

A theoretical investigation is done to study the propagation of dust-acoustic (DA) solitary waves in a dusty plasma system containing dynamic positively as well as negatively charged warm dust species and nonthermally distributed ion and electron species. The standard reductive perturbation method is employed to derive the (3+1)-dimensional cylindrical Kadomstev–Petviashvili (KP) equation (also known as cylindrical Korteweg–de Vries equation), which admits solitary wave solution for small but finite amplitudes. The parametric regimes for the existence of DA solitary waves are obtained. Two modes, namely, slow and fast are observed corresponding to different phase velocities. The slow mode has negative solitary pulses, whereas the fast mode contains both positive and negative DA solitary waves. It is shown that the ratio of positively charged dust to negatively charged dust number density significantly modifies the basic features of the DA solitary waves. The noteworthy effects of other parameters (viz. the nonthermal parameter and ion-to-electron temperature ratio) on the basic properties (namely, phase speed, polarity, amplitude, and width) of the DA solitary waves are also mentioned. The fundamental features and the underlying physics of the electrostatic solitary structures that are relevant to cometary tails, upper mesosphere, Jupiter’s magnetosphere, etc., are briefly discussed.

Do civilian complaints against police get punished?

Law enforcement institutions are tasked with a complicated undertaking that involves maintaining community safety and, at times, making arrests while exercising care in their interaction with private citizens. Errors may have dramatic consequences for civilians, police and the criminal justice system. Given limited observability of law enforcement agents’ behavior, one way to mitigate the principal-agent problem is to rely on signals from civilians via complaints. At the same time, civilian complaints may result in reputational and financial losses for the criminal justice institutions. This paper empirically investigates one way in which criminal justice institutions respond to civilian complaints. Namely, criminal prosecutors can upcharge a defendant who files a civil complaint against law enforcement. By upcharging, the prosecutor can increase the likelihood that a defendant will accept a plea deal, thus preventing the defendant from seeking monetary damages in civil court (Heck vs. Humphrey, 1994). Using data on citizen complaints and criminal charge outcomes from Cook County (Illinois), we find a strong causal link between a citizen filing a complaint and the total number of charges filed.

Scattering theory of delicate topological insulators

We study the scattering theory of delicate topological insulators (TIs), which are novel topological phases beyond the paradigm of the tenfold way, topological quantum chemistry, and the symmetry indicator method. We demonstrate that the phase of the reflection amplitude can probe the delicate topology by capturing a characteristic feature of a delicate TI. This feature is the returning Thouless pump, where an integer number of charges are pumped forward and backward in the first and second half of the adiabatic cycle respectively. As a byproduct of our analysis we show that requiring additional symmetries can stable the boundary states of a delicate TI beyond the conventional requirement of a sharply defined surface. Furthermore, we propose a photonic crystal experiment to implement a delicate TI and measure its reflection phase which reveals the delicate topology.

Trends in outcomes and racial disparities in adult hospitalizations for immune thrombocytopenia over a decade.

Immune thrombocytopenia (ITP) is a diagnosis of exclusion characterized by a low platelet count in patients for whom other etiologies have been ruled out. It occurs due to autoimmune-mediated platelet destruction and thrombopoietin deficiency. ITP is a rare hematologic disorder in adults, and scarce information exists on the hospitalization outcomes among these patients. To address this knowledge gap, we conducted a nationwide population-based study from 2010 to 2019 using the National Inpatient Sample. We found a trend toward an increase in the annual admissions for ITP (from 392.2 to 417.3, p = 0.07). There was a decrease in mortality exclusively for White patients over the period studied (p = 0.03), which was not seen in Black or Hispanic patients. There was an increase in total charges adjusted for inflation for all subgroups (p < 0.01). Length of stay decreased during the decade analyzed (p < 0.01) for the total population and most subgroups. The rates of epistaxis and melena increased (p < 0.01), while rates of intracranial hemorrhage and hematemesis did not change significantly. Advances have been made in the ITP management over the past decade. However, this has not resulted in a decrease in the number of hospitalizations or total healthcare charges during hospitalization. Furthermore, a decrease in mortality was observed in White patients but not in other races. Prospective studies are needed to better characterize the financial burden of the disease, as well as to investigate racial variability in access to care, disease behavior, and response to treatment.

Mild traumatic brain injury increases engagement in criminal behaviour 10 years later: a case-control study.

Sustaining a mild traumatic brain injury (mTBI) has been linked to increased criminal behaviour in later life. However, previous studies have not controlled for the number of injuries, gender, social deprivation, impact of past behaviour, or link to offence type. This study aims to determine if people who experienced a single or multiple mTBI have increased risk of criminal behaviour 10 years post-injury than matched orthopaedic controls. This was a case control study of adults (aged >16 years) who experienced a medically diagnosed mTBI and controls who experienced a lower limb fracture (with no TBI) over a 12-month period (01/01/2003-31/12/2003). Participants were identified within Stats New Zealand's Integrated Data Infrastructure (national database including health and justice records). Participants who experienced a subsequent TBI (post-2003), who were not resident in New Zealand, and who died by 2013 were excluded. Case and controls were matched by age, sex, ethnicity, deprivation index and pre-injury criminal history. The study included N = 6,606 mTBI cases and N = 15,771 matched trauma controls. In the 10 years after injury, people experiencing a single mTBI had significantly higher numbers of violent charges (0.26 versus 0.21, p < 0.01) and violent convictions (0.16 versus 0.13, p < 0.05) but not for all court charges and convictions. Analysis of those with a history of prior mTBIs yielded larger effects, with significantly higher numbers of violent charges (0.57 versus 0.24, p < 0.05) and violent convictions (0.34 versus 0.14, p < 0.05). For males, the single mTBI case group had a significantly higher number of violent charges (0.40 versus 0.31, p < 0.05) and violent convictions (0.24 versus 0.20, p < 0.05) but this was not observed for females or all offence types. Experiencing multiple mTBIs over the lifetime increases the number of subsequent violence-related charges and convictions but not for all offence types in males but not for females. These findings highlight the need for improved recognition and treatment of mTBI to prevent future engagement in antisocial behaviour.

Theoretical analysis of low frequency dust cyclotron waves with dust charge variations

The propagation of nonlinear dust cyclotron (DC) cnoidal waves having superthermal distributed electrons and ions in the presence of external magnetic field and adiabatic dust charge variation is investigated. The effect of dust charge variation is profoundly modified due to the presence of the superthermal electrons and ions. The dust charge variation parameter decreases with an increase in the superthermality index of ions. Adopting the reductive perturbation approach, it is shown that the dynamics of the cnoidal structure is modeled by a Korteweg–de Vries equation. It is found that only negative potential DC cnoidal and solitary structures are observed in such a plasma. The results further reveal that the cnoidal structures strongly depend on the degree of superthermality, dust charge variation parameter, temperature and number density of fluid particles, angle of obliqueness, as well as on the magnetic field strength. The numerical results confirm that as the dust charge variation enters the picture, amplitude as well as the width of the cnoidal waves enhances. Furthermore, the analysis is performed through Sagdeev potential, plane phase plot and spatial variation of potential to elucidate various aspects of the cnoidal wave dynamics in the presence of the adiabatic dust charge variation.

Topological Faraday Effect for Optical Vortices in Magnetic Films.

Here we experimentally demonstrate the topological Faraday effect-the polarization rotation caused by the orbital angular momentum of light. It is found that the Faraday effect of the optical vortex beam passing through a transparent magnetic dielectric film differs from the Faraday effect for a plane wave. The additional contribution to the Faraday rotation depends linearly on the topological charge and radial number of the beam. The effect is explained in terms of the optical spin-orbit interaction. These findings underline the importance of using the optical vortex beams for studies of magnetically ordered materials.

Hydrogen production from simulated seawater by microwave liquid discharge: A new way of green production

Given the current shortage of freshwater resources and the global energy trend is changing to clean and efficient energy, this paper first attempts to use microwave plasma technology for hydrogen production from simulated seawater. The purpose is to build a plasma reactor with unique characteristics of stable operation, which provides the possibility of direct hydrogen production from seawater using plasma technology. To increase hydrogen production and overcome the problem of unstable discharge of pure water, methane (CH4) is introduced into the liquid to realize the gas–liquid two-phase discharge. At different conductivity and CH4 feed flow, the performance of the reactor was evaluated by hydrogen production, hydrogen production energy efficiency, and energy conversing efficiency. The plasma reaction was limited by the optimum conductivity of the solution. At conductivity of 1800 μS/cm, the discharge product was mainly hydrogen, the hydrogen production can reach 2202.3 mL/min, and energy efficiency of hydrogen production and energy conversion efficiency were also increased by 59.6% and 64.8% compared with the pure water experiment. It showed that the change of conductivity significantly affected the plasma chemical reaction. This difference is mainly related to the change of conductivity affecting the number of charges in the solution and and the catalysis of chloride ions. In addition, the optical characteristics and bubble dynamics during the discharge process were also studied to better understand the complex behavior of the plasma reactor. This method proves the huge potential of the reactor for hydrogen production from seawater without a catalyst and provides a new reference for the subsequent hydrogen production industry.

Charged Ice Particle Beams with Selected Narrow Mass and Kinetic Energy Distributions.

Small ice particles play an important role in atmospheric and extraterrestrial chemistry. Circumplanetary ice particles that are encountered by space probes at hypervelocities play a critical role in the determination of surface and subsurface properties of their source bodies. Here we present an apparatus for the generation of low-intensity beams of single mass-selected charged ice particles under vacuum. They are produced via electrospray ionization of water at atmospheric pressure and undergo evaporative cooling when transferred to vacuum through an atmospheric vacuum interface. m/z selection is achieved through two subsequent quadrupole mass filters operated in the variable-frequency mode within a range of m/z values between 8 × 104 and 3 × 107. Velocity and charge of the selected particles are measured using a nondestructive single-pass image charge detector. From the known electrostatic acceleration potentials and settings of the quadrupoles the particle masses could be obtained and be accurately controlled. It has been shown that the droplets are frozen within the transit time of the apparatus such that ice particles are present after the quadrupole stages and finally detected. The demonstrated correspondence between particle mass and specific quadrupole potentials in this device allows preparation of beams of single particles with a repetition rate between 0.1 and 1 Hz with various diameter distributions from 50 to 1000 nm at 30-250 eV of kinetic energy per charge. This corresponds to velocities and particle masses quickly available between 600 m/s (80 nm) and 50 m/s (900 nm) and particle charge numbers (positive) between 103 and 104[e], depending upon size.