Unit Charge Research Articles

Effect of Counterion Size on the Structure of a Flexible Polyelectrolyte Chain in Low-Polar Solvents

The influence of the counterion size on the conformational behavior of a single polyelectrolyte chain in a dilute solution in low-polar media has been studied by molecular dynamics. Modeling has been performed both for small counterions, which are smaller in size than the monomer unit, and for large counterions, which are several times larger in size than the monomer unit. It has been found that the chain gyration radius Rg depends nonmonotonically on the counterion size. The minimum value of Rg is observed when the size of counterions is comparable with the size of the monomer unit. The growth of Rg with increasing size of counterions results from the increasing contribution of excluded volume interactions, whereas its growth with decreasing size of counterions is due to the formation of elongated chains of dipoles. The dependence of the multiplet structure formed in media with strong electrostatic interactions on the fraction of charged chain units and the counterion size is analyzed.

Single-Cell High-Resolution Detection and Quantification of Protein Isoforms Differing by a Single Charge Unit.

Isoelectric focusing (IEF) is an electrophoretic technique that enables the separation of proteins based on their isoelectric points. Until recently, this valuable method was not feasible for single-cell applications, which are necessary to interrogate heterogeneous cell populations. Herein we highlight a recently published method enabling the analysis of single-cell proteomics, which utilizes microfluidics coupled with IEF, photocapture, and immunoprobing of the protein in the same micro-gel, which can be stripped and reprobed multiple times.

Search for heavy charged long-lived particles in proton–proton collisions at [formula omitted] using an ionisation measurement with the ATLAS detector

This Letter presents a search for heavy charged long-lived particles produced in proton–proton collisions at s=13TeV at the LHC using a data sample corresponding to an integrated luminosity of 36.1fb−1 collected by the ATLAS experiment in 2015 and 2016. These particles are expected to travel with a velocity significantly below the speed of light, and therefore have a specific ionisation higher than any high-momentum Standard Model particle of unit charge. The pixel subsystem of the ATLAS detector is used in this search to measure the ionisation energy loss of all reconstructed charged particles which traverse the pixel detector. Results are interpreted assuming the pair production of R-hadrons as composite colourless states of a long-lived gluino and Standard Model partons. No significant deviation from Standard Model background expectations is observed, and lifetime-dependent upper limits on R-hadron production cross-sections and gluino masses are set, assuming the gluino always decays to two quarks and a 100 GeV stable neutralino. R-hadrons with lifetimes above 1.0 ns are excluded at the 95% confidence level, with lower limits on the gluino mass ranging between 1290 GeV and 2060 GeV. In the case of stable R-hadrons, the lower limit on the gluino mass at the 95% confidence level is 1890 GeV.

Structure, Function and Inhibition of Poly(ADP-ribose)polymerase, Member 14 (PARP14).

Poly(ADP-ribose)polymerase, member 14 (PARP14, alternatively named ARTD8, BAL2, and COAST6) is an intracellular mono(ADP-ribosyl) transferase. PARP14 transfers a negatively charged ADP-ribose unit from a donor NAD+ molecule onto a target protein, post-translationally. PARP14's domain architecture consists of three macrodomains (Macro1, Macro2 and Macro3), a WWE domain and an ARTD (or catalytic domain). The Macro2 and Macro3 domains bind ADPribose (ADPr) with high affinity, whereas the WWE domain stabilizes the protein structure by binding to ADPr derivatives. The catalytic domain is involved in binding the NAD+ and catalyzing the mono- ADP-ribosylation reaction. PARP14 has been identified as a possible anti-cancer and antiinflammatory target. Acting as a transcriptional co-activator for STAT6, PARP14 acts to promote the over activation of the Th2 immune response, thus promoting the metabolic change to an anaerobic state (Warburg effect) and activation of cell survival pathways through JNK2 and the PGI/AMF complex. These changes are consistent with the metabolic sophistication observed in cancer, and the immune imbalance in inflammatory diseases. Current literature on selective and unselective PARP14 inhibitors are reviewed and discussed. Although there is no evidence that selective PARP inhibitors would be advantageous we have proposed some strategies for future design of selective PARP14 inhibitors.

Enhancement of betatron x rays through asymmetric laser wakefield generated in transverse density gradients

Laser wakefield acceleration of electrons usually offers an axisymmetry around the laser propagation axis. Thus, the accelerating electrons that are focused on axis often execute small transverse oscillations. In this Article, we propose a simple scheme to break this symmetry, which enhances the transverse wiggling of electrons and boosts the betatron radiation emission. Through 3D particle-in-cell simulations, we show that sending the laser with a small angle of incidence on a transverse plasma density gradient generates an asymmetric wakefield. It first provokes injection and then increases the wiggling of the electrons through the transverse shifting of the wakefield axis which occurs when the laser pulse leaves the gradient. Consequently, we show that the radiated energy per unit of charge can increase by a factor $>20$ when using this scheme, and that the critical energy of the radiation quintuples compared with a reference case without the transverse density gradient.

Complex instantons in sigma models with chemical potential

We analyze two-dimensional nonlinear sigma models at nonzero chemical potentials, which are governed by a complex action. In the spirit of contour deformations (thimbles), we extend the fields into the complex plane, which allows us to incorporate the chemical potentials $\ensuremath{\mu}$ as twisted boundary conditions. We write down the equations of motion and find exact BPS-like solutions in terms of pairs of (anti)holomorphic functions, in particular generalizations of unit charge and fractional instantons to generic $\ensuremath{\mu}$. The decay of these solutions is controlled by the imaginary part of $\ensuremath{\mu}$ and a vanishing imaginary part causes jumps in the action. We analyze how the total charge is distributed into localized objects and to what extent these are characterized by topology.

Supernova 1987A constraints on sub-GeV dark sectors, millicharged particles, the QCD axion, and an axion-like particle

We consider the constraints from Supernova 1987A on particles with small couplings to the Standard Model. We discuss a model with a fermion coupled to a dark photon, with various mass relations in the dark sector; millicharged particles; dark-sector fermions with inelastic transitions; the hadronic QCD axion; and an axion-like particle that couples to Standard Model fermions with couplings proportional to their mass. In the fermion cases, we develop a new diagnostic for assessing when such a particle is trapped at large mixing angles. Our bounds for a fermion coupled to a dark photon constrain small couplings and masses ≲ 200 MeV, and do not decouple for low fermion masses. They exclude parameter space that is otherwise unconstrained by existing accelerator-based and direct-detection searches. In addition, our bounds are complementary to proposed laboratory searches for sub-GeV dark matter, and do not constrain several benchmark-model targets in parameter space for which the dark matter obtains the correct relic abundance from interactions with the Standard Model. For a millicharged particle, we exclude charges between 10−9–few×10−6 in units of the electron charge, also for masses ≲ 200 MeV; this excludes parameter space to higher millicharges and masses than previous bounds. For the QCD axion and an axion-like particle, we apply several updated nuclear physics calculations and include the energy dependence of the optical depth to accurately account for energy loss at large couplings. These corrections allow us to rule out a hadronic axion of mass between 0.1 and a few hundred eV, or equivalently to put a bound on the scale of Peccei-Quinn symmetry breaking between a few×104 and 108 GeV, closing the hadronic axion window. For an axion-like particle, our bounds disfavor decay constants between a few×105 GeV up to a few×108 GeV, for a mass ≲ 200 MeV. In all cases, our bounds differ from previous work by more than an order of magnitude across the entire parameter space. We also provide estimated systematic errors due to the uncertainties of the progenitor.

Wear Mechanism and Mass Loss Characteristic of Arcing Contacts in SF6 Circuit Breaker in Making Process

Large-capacity capacitor banks have been used to control the reactive power of ultra high voltage ac grid in China. The high switching inrush current of SF6 circuit breakers used for large-capacity capacitor banks has caused great mechanical wear after arc ablation, which leads to the serious erosion of the arcing contacts of the circuit breakers, thus shortening the electrical life. To improve the electrical life of circuit breakers, the wear mechanism and mass loss characteristic of arcing contacts in the making process were studied in this paper. Through erosion experiments in the making process and arc ablation experiments in the circuit breaker test device, the wear mechanism and the mass loss characteristics were analyzed via the detection of worn contacts and wear theory. At normal temperature, the wear mechanism is mainly abrasive wear. At high temperature, the wear mechanisms in three stages mainly include adhesive and abrasive wears. When the closing inrush current amplitudes are 10, 20, and 30 kA, the mass loss of mechanical wear is greater than that of arcing ablation. The total mass loss and mass loss rate per unit charge increase with the interference radius between two contacts and with test current. However, with current amplitude higher than 20 kA, the total mass loss rate decreases. Suggestions to reduce wear are proposed to improve the electrical life of circuit breakers.

Present status of theoretical understanding of charge changing processes at low beam energies

A model for the evaluation of charge-state distributions of fast heavy ions in solid targets is being developed since late eighties in terms of ETACHA code. Time to time it is being updated to deal with more number of electrons and non-perturbative processes. The calculation approach of the recent one, which is formulated for handling the non-perturbative processes better, is different from the earlier ones. However, the experimental results for the projectiles up to 28 electrons can be compared with the predictions from any versions of ETACHA code. Though earlier versions are not meant for the non-perturbative cases, but the detail comparison suggests that predictions from an earlier version is somewhat superior to that of the recent version. However, certain difference up to 4 units of charge found between the earlier version and experimental results on the mean charge states and it is attributed to nonradiative electron capture taking place at the exit surface in the influence of wake and dynamic screening effects. This mechanism can play its role in multiply charge formation in the electrospray ionization of big molecules.

Topologic configuration of electron

Motion of an electron is much different from that of a kind of matter in classical mechanics. Although it is impossible to directly observe the configuration of a bare electron, it is never as simple as to treat it as a three-dimensional (3D) particle in the microscopic world because the electron itself certainly has its own topological configuration, so that it presents a field of a unit charge and a spin, etc. An electron produces a magnetic field in motion and also can radiate or absorb an electromagnetic field in its accelerating motions. Thus, the topological configuration of an electron must be related or similar to the configurations of the magnetic field and electromagnetic wave. Starting from the topological configuration of a single electromagnetic wave, it is possible to derive that an electron is a quantized left-hand Möbius strip, on the center of which there exists an anti-neutrino. The Möbius strip excites a [Formula: see text] circumference of a unit negative charge and a linear electric field of a [Formula: see text] torsion and can explain the wave feature of the electron and the essential cause of producing a magnetic field and radiating an electromagnetic wave as well as predict that the second-order tensor field among the three quarks in a proton has a topological configuration of right-hand three-leaf knot and can excite a [Formula: see text] circumference of a unit positive charge and a linear electric field of a [Formula: see text] torsion, which is just allelomorphic to an electron.

Structure-based viscosity model development for titania aluminosilicate slags

ABSTRACTBased on the structure of melts, a model has been developed that estimates the viscosity of the fully liquid melts in the CaO–MgO–Al2O3–SiO2–TiO2 systems. Three kinds of tetrahedral ([SiO4]4−, [AlO4]5−, and [TiO4]4−) are considered in the titania aluminosilicate slag. According to the hole theory of melts, this model provides a link between the viscosity and the structures of the melts. The present model is capable of predicting the viscosities in the CaO–MgO-–Al2O3–SiO2–TiO2 systems with wide composition and temperature ranges above liquidus; the average of relative errors for this model was approximately 20.0%. From the model calculation results, the addition of TiO2 decrease the viscosity of slag under non-reducing atmosphere. The ability of increasing viscosity follows the order: SiO2> Al2O3> TiO2> CaO. Due to the charge compensation and unit size effect, the replacement of TiO2 by Al2O3 will result in the increase of viscosity.

The development characteristics of the discontinuous leader under the positive switching impulse with low rate of voltage rising

Discontinuous leader development is the most important discharge process under the application of the switching impulse voltage with the low rate of voltage rising, which is of great significance to study the external insulation characteristics of ultra-high voltage (UHV) large scale air gap. Based on the CMOS high-speed camera, a discharge test with different operating impulse voltage is carried out by constructing a comprehensive observation platform of rod-plate air gap discharge, and a clear discontinuous leader development process picture is captured. Moreover, the leader current, injection charge and leader channel unit length charge, and their characteristics of the change trend are also obtained. Further analysis based on the experimental results shows that the discontinuous leader development under the action of the impulse voltage with low rate of voltage rising has two different laws. Finally, this paper uses the thermodynamic equation, combined with the test results, the channel temperature changes in the discontinuous leader development stagnation stage were calculated. The results show that the leader channel temperature is still greater than 1500 K in the hundreds of microsecond time scales in the leader stagnation stage, and the subsequent leader can continue to develop on the original leader channel.

Precision Measurement of Cosmic-Ray Nitrogen and its Primary and Secondary Components with the Alpha Magnetic Spectrometer on the International Space Station.

A precision measurement of the nitrogen flux with rigidity (momentum per unit charge) from 2.2GV to 3.3 TV based on 2.2×10^{6} events is presented. The detailed rigidity dependence of the nitrogen flux spectral index is presented for the first time. The spectral index rapidly hardens at high rigidities and becomes identical to the spectral indices of primary He, C, and O cosmic rays above ∼700 GV. We observed that the nitrogen flux Φ_{N} can be presented as the sum of its primary component Φ_{N}^{P} and secondary component Φ_{N}^{S}, Φ_{N}=Φ_{N}^{P}+Φ_{N}^{S}, and we found Φ_{N} is well described by the weighted sum of the oxygen flux Φ_{O} (primary cosmic rays) and the boron flux Φ_{B} (secondary cosmic rays), with Φ_{N}^{P}=(0.090±0.002)×Φ_{O} and Φ_{N}^{S}=(0.62±0.02)×Φ_{B} over the entire rigidity range. This corresponds to a change of the contribution of the secondary cosmic ray component in the nitrogen flux from 70% at a few GV to <30% above 1TV.

Structural unit charge density and molecular cation templating effects on orientational geometric isomerism and interlayer spacing in 2-D uranyl sulfates

The new uranyl aqua sulfate compound [({CH3}3N2C3H3{CH2COOH})(H3O)] [(UO2)2(SO4)3(H2O)]·1.5H2O was synthesized and the crystal structure determined. The two-dimensional uranyl-aqua sulfate compound exhibits a previously reported anionic structural unit topology, but features an interstitial complex incorporating hydronium in the form of a disorder Zundel cation and the cation moiety from the ionic liquid 1-carboxymethyl 3-methylimidazolium bistriflimide [HBetMIm][Tf2N], which forms hydrogen bonding dimer pairs. An analysis of similar uranyl sulfate complexes from the literature is conducted to explore the relative importance and role of structure directing factors in alkylammonium charge-balanced two-dimensional uranyl sulfates. A correlation is observed between structural unit charge density and interlayer spacing, with a concomitant direction of structural and orientational geometric isomerism of the anionic structural unit. We discuss the role of synthetic conditions and molecular cation properties in directing structural unit formation through charge density matching and hydrogen bonding.

Solving the Perennial Electricity Crises Management of Residential Consumer through DRPs in Sub-Saharan Africa: A Case Study of Ghana’s Electricity Market using Incentivized Credit Function Technique

This paper focuses on how demand response programs (DRPs) can be used in sub-Saharan Africa to resolve residential electricity management crises using Ghana as a case study with particular interest in retailer’s returns as against the flat rate tariff system in use. Applying an incentive-based DRP model on unit charge per kWh data for residential consumers of Ghana, our simulation results indicated that, retailers can improve their revenue by about 4% or more if DRPs are implemented. Thus, sub-Saharan African countries can introduce DRPs to solve their electricity management crises in their economies, optimize electricity usage and attract investors into the electricity sector.

Programming Planck units from a virtual electron: a simulation hypothesis

The simulation hypothesis proposes that all of reality is an artificial simulation. In this article I describe a simulation model that derives Planck level units as geometrical forms from a virtual (dimensionless) electron formula $f_{e}$ that is constructed from 2 unit-less mathematical constants; the fine structure constant $\alpha$ and $\Omega = 2.00713494 \ldots$ ( $ f_{e} = 4\pi^{2}r^{3}$ , $ r = 2^{6} 3 \pi^{2} \alpha \Omega^{5}$ ). The mass, space, time, charge units are embedded in $ f_{e}$ according to these ratios; $ M^{9}T^{11}/L^{15} = (AL)^{3}/T$ ( $ {\rm units} = 1$ ), giving mass $ M=1$ , time $T=2\pi$ , length $ L=2\pi^{2}\Omega^{2}$ , ampere $ A = (4\pi \Omega)^{3}/\alpha$ . We can thus, for example, create as much mass M as we wish but with the proviso that we create an equivalent space L and time T to balance the above. The 5 SI units kg, m, s, A, K are derived from a single unit $ u = \sqrt{({\rm velocity/mass})}$ that also defines the relationships between the SI units: $ {\rm kg}= u^{15}$ , $ {\rm m}= u^{-13}$ , $ {\rm s}= u^{-30}$ , $ {\rm A}= u^{3}$ , $ k_{B} = u^{29}$ . To convert MLTA from the above $ \alpha$ , $ \Omega$ geometries to their respective SI Planck unit numerical values (and thus solve the dimensioned physical constants G, h, e, c, me, kB) requires an additional 2-unit-dependent scalars. Results are consistent with CODATA 2014. The rationale for the virtual electron was derived using the sqrt of momentum P and a black-hole electron model as a function of magnetic-monopoles AL (ampere-meters) and time T.

Two Macrocycles in One Shot: Synthesis, Spectroscopy, Photophysics, and Tautomerism of 23-Oxahemiporphycene and 21-Oxacorrole-5-carbaldehyde.

The synthesis of 23-oxahemiporphycene, the first monooxa analogue of hemiporphycene, a structural isomer of porphyrin, is reported. Its generation under McMurry reaction conditions is surprisingly accompanied by the appearance of a formyl derivative of oxacorrole, 21-oxacorrole-5-carbaldehyde. A mechanism for the formation of the latter is proposed, relying on pinacol rearrangement of titanium pinacolate. The structures of the most stable tautomeric forms are established for both compounds based on IR and NMR spectra combined with DFT calculations. Spectral and photophysical characteristics are compared with those of structurally similar macrocycles. Replacement of one nitrogen by oxygen in hemiporphycene has only a minor impact. In contrast, for corrole it leads to the enhancement of stability and to strongly reduced rates of nonradiative deactivation of the lowest excited singlet state. This is explained by the planarity of oxacorroles, achieved by removing one of the inner hydrogen atoms from the inner cavity. Unusual crystal packing is observed for the protonated form of 23-oxahemiporphycene, which exhibits a π-π stacked columnar alignment of positively charged macrocycle units.

Explicit screening full band quantum transport model for semiconductor nanodevices

State of the art quantum transport models for semiconductor nanodevices attribute negative (positive) unit charges to states of the conduction (valence) band. Hybrid states that enable band-to-band tunneling are subject to interpolation that yields model dependent charge contributions. In any nanodevice structure, these models rely on device and physics specific input for the dielectric constants. This paper exemplifies the large variability of different charge interpretation models when applied to ultrathin body transistor performance predictions. To solve this modeling challenge, an electron-only band structure model is extended to atomistic quantum transport. Performance predictions of Metal-Oxide-Semiconductor Field-Effect Transistors (FET) and tunneling FETs confirm the generality of the new model and its independence of additional screening models.

CALCULATION OF STATIC PARAMETERS OF SILICON DIODE CONTAINING δ-LAYER OF TRIPLE-CHARGED POINT DEFECTS IN SYMMETRIC p–n-JUNCTION

The study of semiconductor materials and devices containing a narrow layer of impurity atoms and/or intrinsic point defects of the crystal lattice is of fundamental and practical interest. The aim of the study is to calculate the electric parameters of a symmetric silicon diode, in the flat p–n-junction of which a δ-layer of point triple-charged t-defects is formed. Such a diode is called p–t–n-diode, similarly to p–i–n-diode.Each t-defect can be in one of the three charge states (−1, 0, and +1; in the units of the elementary charge). It is assumed that at room temperature all hydrogen-like acceptors in p-region and hydrogen-like donors in n-region are ionized. It was assumed that the cross-section for v-band hole capture on t-defects is greater than the cross-section for c-band electron capture on t-defects.The system of stationary nonlinear differential equations, which describe in the drift-diffusion approximation a migration of electrons and holes in semiconductors, is solved numerically. The static capacityvoltage and current-voltage characteristics of the silicon diode with nondegenerate regions of pand n-type of electrical conductivity are calculated for forward and reverse electric bias voltage.It is shown by calculation that in the p–t–n-diode containing the δ-layer of t-defects, at the forward bias a region of current density stabilization occurs. At the reverse bias the current density in such a diode is much greater than the one in a p–n-diode without t-defects. With the reverse bias the capacitance of the p–t–n-diode, in contrast to the p–n-diode, increases at first and then decreases.

Structural and spectroscopic characterization of bis[1-(diaminomethylene)thiouron-1-ium] naphthalene-1,5-disulfonate

Single crystals of bis[1-(diaminomethylene)thiouron-1-ium] naphthalene-1,5-disulfonate (1) are grown using growth solution technique. The compound crystallizes in the centrosymmetric C2/c space group of the monoclinic system with four molecules per unit cell. The arrangement of oppositely charged units, i.e. 1-(diaminomethylene)thiouron-1-ium cations and naphthalene-1,5-disulfonate anions in the crystal is mainly determined by the ionic and the NH⋯O hydrogen bonding interactions. Hirshfeld surface and the analysis of 2D fingerprint plots are illustrating both qualitatively and quantitatively interactions governing the supramolecular arrangement. The compound was also characterized by FT-IR and Raman spectroscopies. The vibrational assignment of the characteristic bands of the functional groups have been supported by the isotopic frequency shift.