bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Study between Transforaminal Lumbar Interbody Fusion and Posterolateral Fusion for Treatment of Spondylolisthesis: Clinical Outcomes and Spino-Pelvic Sagittal Balance Parameters
Authors: Farrokhi Majid Reza , Eghbal Keyvan , Mousavi Seyed Reza , Moumani Mustafa , Bazyari Khshayar , chaurasia Bipin
Published: March 2021

Objective This retrospective study aims to compare the clinical and radiological outcomes of posterolateral fusion (PLF) with transforaminal lumbar interbody fusion (TLIF + PLF) for the treatment of patients with low-grade spondylolisthesis.

Methodology A total of 77 adult patients ≥18 years with low-grade spondylolisthesis, Meyerding grades I and II, were assigned into two groups: 36 patients treated with PLF and 41 patients treated with TLIF + PLF. The PLF group is composed of the patients that were operated with pedicle screw and the TLIF + PLF group is composed of the ones that were operated with fixation and TILF by autografting. Clinical evaluation was performed using the spino-pelvic sagittal balance, Numeric Rating Scale, Oswestry Disability Index, blood loss, operation times, and postoperative hospital stay of the PLF vs TLIF groups. The incidences of postoperative low back pain and radicular pain in the two groups were also recorded. Radiography was performed preoperatively and postoperatively to assess spino-pelvic parameters.

Results Significant restoration of spino-pelvic sagittal balance was observed in the TLIF group after surgery, and all spino-pelvic sagittal balance parameters showed significant improvement in the TLIF group after surgery, while in the PLF group, all spino-pelvic sagittal parameters had improved except the segmental angle lordosis (p = 0.316), which showed no significant difference after surgery in the PLF group. Postoperative pelvic incidence and pelvic tilt significantly improved in the TLIF group in comparison to PLF groups. Hence, TLIF can achieve better postoperative spino-pelvic sagittal balance parameters than PLF. There was no difference in the complication rates for each group. Both groups achieved significant improvement in postoperative clinical outcomes, and there was no significant difference in the incidence of postoperative low back pain or radicular pain between the two groups.

Conclusion Both surgical procedures PLF and TLIF were effective. PLF and TLIF can result in improved clinical and radiological outcomes for patients treated for low-grade spondylolisthesis. TLIF can achieve better restoration of spino-pelvic sagittal balance parameters than PLF alone.
‘People Consider Us Devils’: Exploring Patterns of Exclusion Facing Adolescents with Disabilities in Ethiopia
Authors: Jones Nicola , Seager Jennifer , Yadete Workneh
Published: March 2021

The 2030 Sustainable Development Goals’ call to ‘leave no one behind’ has helped to highlight the importance of investing in inclusive services for persons with disabilities in low- and middle-income countries (LMICs). Evidence on the experiences of young Ethiopians with disabilities remains weak. Drawing on quantitative and qualitative data from 2017 to 2018, this article explores the educational, bodily integrity and psychosocial outcomes of adolescents with different impairment types (visual, hearing and physical) in rural and urban communities. Our findings indicate that young people with disabilities face intersecting barriers to inclusive education, heightened vulnerability to gender- and age-based violence, and increased psychosocial distress compared to peers without disabilities. Implications of these findings for policy and programming, include: the pressing need for specialised training and mentoring of education and other service providers; investments in support networks for parents of adolescents with disabilities; and strengthening of disability-inclusive social protection and referral mechanisms.
Cold ion energization at separatrices during magnetic reconnection
Authors: Zaitsev I. , Divin A. , Semenov V. , Kubyshkin I. , Korovinskiy D. , Deca J. , Khotyaintsev Yu. , Markidis S.
Published: March 2021

Separatrices of magnetic reconnection host intense perpendicular Hall electric fields. The fields are produced by the decoupling of the ion and electron components and are associated with the in-plane electrostatic potential drop between the inflow and outflow regions. The width of these structures is typically less than the ion inertial length, which is small enough to demagnetize ions as they cross the layer. We investigate ion acceleration at separatrices by means of 2D particle-in-cell simulations of magnetic reconnection for two limiting cases: (1) a “GEM-like” setup (here GEM stands for geospace environmental modeling reconnection challenge) with the lobe ion thermal velocity equal to the thermal velocity of the initial current sheet ions, which is comparable to the Alfvén velocity and (2) a “cold” ion setup, in which the temperature of the background lobe ions is 1/100 of the initial current sheet temperature. The separatrix Hall electric field is balanced by the ion inertia term in the cold background simulations. The effect is indicative of the quasi-steady local perpendicular acceleration. The electric field introduces a cross field beam of unmagnetized particles, which makes the ion distribution function strongly non-gyrotropic and susceptible to sub-ion scale instabilities. This acceleration mechanism nearly vanishes in the hot ion background simulations. Our particle-in-cell simulations are complemented by one-dimensional test particle calculations. They show that the hot ion particles experience energy-scattering after crossing the accelerating layer, whereas cold ions are uniformly energized up to the energies comparable to the electrostatic potential drop between the inflow and outflow regions.
Dynamics of domain boundaries at metal–organic interfaces
Authors: Pazoki Sara , Frick Jordan , Dougherty Daniel B.
Published: March 2021

Domain boundaries are a determining factor in the performance of organic electronic devices since they can trap mobile charge carriers. We point out the possibility of time-dependent motion of these boundaries and suggest that their thermal fluctuations can be a source of dynamic disorder in organic films. In particular, we study the C8-BTBT monolayer films with several different domain boundaries. After characterizing the crystallography and diversity of structures in the first layer of C8-BTBT on Au(111), we focus on quantifying the domain boundary fluctuations in the saturated monolayer. We find that the mean squared displacement of the boundary position grows linearly with time at early times but tends to saturate after about 7 s. This behavior is ascribed to confined diffusion of the interface position based on fits and numerical integration of a Langevin equation for the interface motion.
Loss channels affecting lithium niobate phononic crystal resonators at cryogenic temperature
Authors: Wollack E. Alex , Cleland Agnetta Y. , Arrangoiz-Arriola Patricio , McKenna Timothy P. , Gruenke Rachel G. , Patel Rishi N. , Jiang Wentao , Sarabalis Christopher J. , Safavi-Naeini Amir H.
Published: March 2021

We investigate the performance of microwave-frequency phononic crystal resonators fabricated on thin-film lithium niobate for integration with superconducting quantum circuits. For different design geometries at millikelvin temperatures, we achieve mechanical internal quality factors Qi above 105–106 at high microwave drive power, corresponding to 5×106 phonons inside the resonator. By sweeping the defect size of resonators with identical mirror cell designs, we are able to indirectly observe signatures of the complete phononic bandgap via the resonators' internal quality factors. Examination of quality factors' temperature dependence shows how superconducting and two-level system (TLS) loss channels impact device performance. Finally, we observe an anomalous low-temperature frequency shift consistent with resonant TLS decay and find that the material choice can help to mitigate these losses.
Improving molecular force fields across configurational space by combining supervised and unsupervised machine learning
Authors: Fonseca Gregory , Poltavsky Igor , Vassilev-Galindo Valentin , Tkatchenko Alexandre
Published: March 2021

The training set of atomic configurations is key to the performance of any Machine Learning Force Field (MLFF) and, as such, the training set selection determines the applicability of the MLFF model for predictive molecular simulations. However, most atomistic reference datasets are inhomogeneously distributed across configurational space (CS), and thus, choosing the training set randomly or according to the probability distribution of the data leads to models whose accuracy is mainly defined by the most common close-to-equilibrium configurations in the reference data. In this work, we combine unsupervised and supervised ML methods to bypass the inherent bias of the data for common configurations, effectively widening the applicability range of the MLFF to the fullest capabilities of the dataset. To achieve this goal, we first cluster the CS into subregions similar in terms of geometry and energetics. We iteratively test a given MLFF performance on each subregion and fill the training set of the model with the representatives of the most inaccurate parts of the CS. The proposed approach has been applied to a set of small organic molecules and alanine tetrapeptide, demonstrating an up to twofold decrease in the root mean squared errors for force predictions on non-equilibrium geometries of these molecules. Furthermore, our ML models demonstrate superior stability over the default training approaches, allowing reliable study of processes involving highly out-of-equilibrium molecular configurations. These results hold for both kernel-based methods (sGDML and GAP/SOAP models) and deep neural networks (SchNet model).
Early-time symmetry quantifying with thin-shell capsule radiography for pulse shaped implosion
Authors: Chen Bolun , Xia Liqiong , Jiang Wei , Wang Peng , Deng Keli , Jing Longfei , Huang Tianxuan , Ge Fengjun , Zou Shiyang , He Xiaoan , Chen Zhongjing , Yang Jiamin , Jiang Shaoen
Published: March 2021

To achieve ignition with high gain in inertial confinement fusion, precise symmetry control is one of the key issues to guarantee the PdV work converting into the inner energy efficiently and maximize the pressure of the hot spot. The shaped pulse is used to maintain a low adiabat of the shell. A longer pulse and more compressible shell require more rigorous symmetry control, especially the driven symmetry during the picket pulse and main pulse. A surrogate capsule with high Z materials is usually used for the early-time symmetry tuning. The passive diagnosis of the re-emission spheres gives the time-resolved measurement of the first 2 ns, and the precision is mainly affected by the weak signals due to the low radiation temperature of the hohlraum. To compare with the re-emission technique with high Z surrogate capsule, we demonstrated the early-time symmetry tuning for picket pulse by using thin-shell capsule radiography technique. Combined with 1D hydrodynamics simulation and backlit imaging simulation, the driven asymmetry was quantified. A view factor assessment was also carried out by IRAD3D and coincided with the experimental consequences.
Generation of giant electric energy density by adiabatically compressed PIN-PMN-PT ferroelectric single crystals
Authors: Shkuratov Sergey I. , Baird Jason , Antipov Vladimir G. , Chase Jay B.
Published: March 2021

The results are reported herein of experimental investigations of the mechanism of electric breakdown and the generation of high voltage and energy by shock-compressed rhombohedral (1-y-x)Pb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-xPbTiO3 (PIN-PMN-PT) ferroelectric single crystals cut and poled along the [111]c crystallographic direction. PIN-PMN-PT crystals were shock-compressed in a direction perpendicular to the polarization, in either the [11¯0]c or [112¯]c crystallographic directions. Our experiments demonstrated that shocked crystals with thicknesses ranging from 1 to 5 mm are capable of producing high voltage amplitudes of 9–37 kV, with the amplitudes being directly proportional to the crystal thickness. The experimental results indicate that the shock loading direction does not have a significant effect on the generated voltage amplitude. The important finding is that the breakdown fields of adiabatically compressed crystals strongly depend on the crystal thicknesses, and this dependence obeys a power law similar to the one for solid dielectrics at ambient conditions. We found that high electric fields have significant impacts on the dielectric permittivity of poled PIN-PMN-PT crystals and a corresponding effect on the generated energy density. Our experimental results made it possible to determine the relationship between the energy density generated by crystals under shock loading and the crystal thickness. The energy density generated by shocked PIN-PMN-PT crystals is greater by a factor of three than that for high-energy-density Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics currently used in high-power systems, making these crystals very promising ferroelectric materials for high-power applications.
How free exciton–exciton annihilation lets bound exciton emission dominate the photoluminescence of 2D-perovskites under high-fluence pulsed excitation at cryogenic temperatures
Authors: Kaiser Milian , Li Yang , Schwenzer Jonas , Jakoby Marius , Allegro Isabel , Gerhard Marina , Koch Martin , Ducinskas Algirdas , Richards Bryce S. , Graetzel Michael , Milić Jovana V. , Paetzold Ulrich W. , Howard Ian A.
Published: March 2021

Photoluminescence (PL) spectra of atomically thin 2D lead iodide perovskite films are shown to depend on excited-state density, especially at cryogenic temperatures. At high excited-state densities and low temperatures, free exciton (FE) emission is so suppressed by exciton–exciton annihilation (EEA) that other—normally much weaker—emissions dominate the PL spectrum, such as emission from bound excitons (BEs) or PbI2 inclusions. In the Ruddlesden–Popper perovskite with phenethylammonium (PEA) ligands (PEA2PbI4, PEPI), FE emission dominates at all temperatures at the excited-state densities reached with continuous wave excitation. At higher excited state densities reached with femtosecond pulsed excitation, the PL at temperatures under 100 K is dominated by BE emission redshifted from that of FE by 40.3 meV. Weak emission from PbI2 inclusions 170 meV higher in energy than FE PL is also observable under these conditions. Equilibrium between BE and FE states explains why FE emission first increases with decreasing temperature from 290 until 140 K and then decreases with decreasing temperature as the BEs become stable. A Dion–Jacobson (DJ) material based on 1,4-phenyl-enedimethanammonium (PDMA) supports the reduction of FE emission by EEA at cryogenic temperatures. However, in the PDMA-based DJ material, BE emission is never as pronounced. At low temperatures and high-excited state densities caused by pulsed excitation, a broad emission redshifted by 390 meV from the FE dominates. Based on comparison with temperature-dependent measurements of PbI2 films, this emission is suggested to arise from PbI2 inclusions in the material. Possible avenues for improving PL at room temperature are discussed concerning these findings.
Optically transparent antenna based on carrier-doped three-layer stacked graphene
Authors: Kosuga Shohei , Nagata Shunichiro , Kuromatsu Sho , Suga Ryosuke , Watanabe Takeshi , Hashimoto Osamu , Koh Shinji
Published: March 2021

We fabricated an optically transparent monopole antenna using graphene film and investigated the feasibility of the film as an electrode material for antennas. A low sheet resistance (80 Ω/sq) was attained by stacking the graphene films and carrier doping with an ionic liquid. The optical transmittance of the carrier-doped three-layer stacked graphene film was greater than 90%, enabling it to be embedded in highly transparent objects without altering their landscape. Using the monopole antenna structure with a metal ground plane, we measured the reflection and radiation characteristics of the graphene monopole antenna, excluding the contribution from the power feeding components. The radiation efficiency of the graphene monopole antenna, which was measured by the Wheeler cap method, was determined to be 52.5% at 9.8 GHz. Through the measurements of the graphene monopole antenna, we demonstrated that the carrier-doped three-layer stacked graphene film can be used as an electrode material for optically transparent antennas.
Neural network surrogate of QuaLiKiz using JET experimental data to populate training space
Authors: Ho A. , Citrin J. , Bourdelle C. , Camenen Y. , Casson F. J. , van de Plassche K. L. , Weisen H. ,   JET Contributors
Published: March 2021

Within integrated tokamak plasma modeling, turbulent transport codes are typically the computational bottleneck limiting their routine use outside of post-discharge analysis. Neural network (NN) surrogates have been used to accelerate these calculations while retaining the desired accuracy of the physics-based models. This paper extends a previous NN model, known as QLKNN-hyper-10D, by incorporating the impact of impurities, plasma rotation, and magnetic equilibrium effects. This is achieved by adding a light impurity fractional density (nimp,light/ne) and its normalized gradient, the normalized pressure gradient (α), the toroidal Mach number (Mtor), and the normalized toroidal flow velocity gradient. The input space was sampled based on experimental data from the JET tokamak to avoid the curse of dimensionality. The resulting networks, named QLKNN-jetexp-15D, show good agreement with the original QuaLiKiz model, both by comparing individual transport quantity predictions and by comparing its impact within the integrated model, JINTRAC. The profile-averaged RMS of the integrated modeling simulations is <10% for each of the five scenarios tested. This is non-trivial given the potential numerical instabilities present within the highly nonlinear system of equations governing plasma transport, especially considering the novel addition of momentum flux predictions to the model proposed here. An evaluation of all 25 NN output quantities at one radial location takes ∼0.1 ms, 104 times faster than the original QuaLiKiz model. Within the JINTRAC integrated modeling tests performed in this study, using QLKNN-jetexp-15D resulted in a speed increase of only 60–100 as other physics modules outside of turbulent transport become the bottleneck.
Interaction of Bragg scattering bandgaps and local resonators in mono-coupled periodic structures
Authors: Cenedese Mattia , Belloni Edoardo , Braghin Francesco
Published: March 2021

Periodic structures have gained attention in the research community since they show attenuation zones in their frequency response, called bandgaps. In this paper, the interactions of two mechanisms of bandgap formation in mono-coupled periodic structures are examined, i.e., Bragg scattering and local resonators. With reference to longitudinal elastic waves, an analytical study is carried out to describe in detail the formation of bandgaps. Local resonators are implemented via piezoelectric inserts shunted with a resonating electrical circuit for which a non-traditional model is needed since the study concerns higher frequencies with respect to those of the subwavelength regime. Design maps and tuning formulas are developed not only for the case of infinite structures, but also for the finite case, highlighting the role of the number of unit cells and that of resonances in the attenuation zones. Among the possible tuning strategies of local resonators, it is shown that the mutual influence between elastic and electric parameters is able to produce a wider attenuation zone, bridging Bragg scattering bandgaps thanks to the effect of local resonators. The analytical findings of this paper are validated with numerical results in an example application.
Aerosol generation in public restrooms
Authors: Schreck Jesse H. , Lashaki Masoud Jahandar , Hashemi Javad , Dhanak Manhar , Verma Siddhartha
Published: March 2021

Aerosolized droplets play a central role in the transmission of various infectious diseases, including Legionnaire's disease, gastroenteritis-causing norovirus, and most recently COVID-19. Respiratory droplets are known to be the most prominent source of transmission for COVID-19; however, alternative routes may exist given the discovery of small numbers of viable viruses in urine and stool samples. Flushing biomatter can lead to the aerosolization of micro-organisms; thus, there is a likelihood that bioaerosols generated in public restrooms may pose a concern for the transmission of COVID-19, especially since these areas are relatively confined, experience heavy foot traffic, and may suffer from inadequate ventilation. To quantify the extent of aerosolization, we measure the size and number of droplets generated by flushing toilets and urinals in a public restroom. The results indicate that the particular designs tested in the study generate a large number of droplets in the size range 0.3 μm–3 μm, which can reach heights of at least 1.52 m. Covering the toilet reduced aerosol levels but did not eliminate them completely, suggesting that aerosolized droplets escaped through small gaps between the cover and the seat. In addition to consistent increases in aerosol levels immediately after flushing, there was a notable rise in ambient aerosol levels due to the accumulation of droplets from multiple flushes conducted during the tests. This highlights the need for incorporating adequate ventilation in the design and operation of public spaces, which can help prevent aerosol accumulation in high occupancy areas and mitigate the risk of airborne disease transmission.
Application of physics-based flow models in cardiovascular medicine: Current practices and challenges
Authors: Vardhan M. , Randles A.
Published: March 2021

Personalized physics-based flow models are becoming increasingly important in cardiovascular medicine. They are a powerful complement to traditional methods of clinical decision-making and offer a wealth of physiological information beyond conventional anatomic viewing using medical imaging data. These models have been used to identify key hemodynamic biomarkers, such as pressure gradient and wall shear stress, which are associated with determining the functional severity of cardiovascular diseases. Importantly, simulation-driven diagnostics can help researchers understand the complex interplay between geometric and fluid dynamic parameters, which can ultimately improve patient outcomes and treatment planning. The possibility to compute and predict diagnostic variables and hemodynamics biomarkers can therefore play a pivotal role in reducing adverse treatment outcomes and accelerate development of novel strategies for cardiovascular disease management.
Integrated package of electron cyclotron emission imaging data processing and forward modeling in OMFIT
Authors: Yu G. , Zhu Y. , Wang Y. , Meneghini O. , Smith S. P. , Zou Y. , Luo C. , Cao J. , Tobias B. , Diallo A. , Kramer G. J. , Ren Y. , Luhmann N. C.
Published: March 2021

An Electron Cyclotron Emission Imaging (ECEI) data analysis module has been developed for the OMFIT platform to accommodate the needs of users at the DIII-D tokamak for physics applications. The user can easily access the ECEI spatial observation windows in the plasma that are calculated based on the automatically retrieved hardware setup and available DIII-D equilibria, perform spectral analysis, and obtain 2D electron temperature fluctuation images. The module provides a powerful data post-processing package for extracting important physics parameters from the 2D measurements, including the radial structure and poloidal mode number of Alfven eigenmodes, as well as the frequency-vs-wavenumber dispersion relationship of broadband MHD. The module propagates characterized synthetic fluctuations for the user, so one can perform forward modeling tasks with simple analytical fluctuations.
The pH-dependent orientation of N3 dye on a gold substrate is revealed using heterodyne-detected vibrational sum frequency generation spectroscopy
Authors: Farah Yusef R. , Krummel Amber T.
Published: March 2021

We report on systematic changes to the adsorption geometry of the dye N3 {[cis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato ruthenium(II)]} on a gold substrate as the pH of the deposition environment is altered. The protonation states of the four —COOH groups of the N3 dye change according to the modified pH conditions, thus affecting the number of —COOH and —NCS functional groups that participate in the adsorption to gold. Here, we use heterodyne detected vibrational sum frequency generation (HD-VSFG) spectroscopy to obtain surface specific vibrational information on both —COOH and —NCS groups as a function of pH of the deposition conditions. Polarization-dependent HD-VSFG yields sets of complex χ(2) spectra, enabling us to perform a simultaneous fitting procedure to the polarization-dependent real and imaginary components and thus extract detailed structural information of the N3/gold interface. Our results show that N3 preferentially adsorbs to gold either with two —COOH groups and one —NCS group in more acidic conditions or with one —COOH group and two —NCS groups in more basic conditions.
On the representation of dense plasma focus as a circuit element
Authors: Auluck S. K. H.
Published: March 2021

The dense plasma focus is a plasma discharge powered by a capacitor bank. Standard diagnostics include the measurement of the time derivative of the current through and the voltage across its connections with the capacitor bank. Interpretation of this diagnostic data often involves some assumptions regarding the representation of the dense plasma focus as a time varying inductance. One of the characteristic features of the current derivative waveform is a relatively sharp dip and an associated sharp voltage spike. This has often been interpreted as a result of a rapid rise in the time varying inductance of the plasma. Sometimes, an anomalous plasma impedance is invoked. This Letter discusses instances where such interpretation creates conceptual difficulties. A first principles approach to the representation of the dense plasma focus as a circuit element reveals some fundamental problems with the traditional representation of plasma focus as a time varying inductance. The anomalous impedance is shown to be necessary to account for the difference in the motional impedance implied by a time-varying inductance in the circuit element representation and a first principles description based on Poynting's theorem. Dynamo effects that convert post-stagnation local motion of plasma into three-dimensional magnetic fields are shown to contribute to the effective inductance of the plasma focus and resolve the observed conceptual difficulties.
Tuning the linear field range of tunnel magnetoresistive sensor with MgO capping in perpendicular pinned double-interface CoFeB/MgO structure
Authors: Cao Zhiqiang , Chen Weibin , Lu Shiyang , Yan Shaohua , Zhang Yu , Zhou Zitong , Yang Yaodi , Li Zhi , Zhao Weisheng , Leng Qunwen
Published: March 2021

A double-interface CoFeB/MgO perpendicular tunnel magnetoresistance (p-TMR) structure has been proposed as a solution to improve the thermal stability of perpendicular magnetic tunnel junction (MTJ)-based devices. In this paper, we have investigated the performance of TMR film stacks by varying the thickness of the MgO cap layer. The resistance area (RA) product and TMR ratio are characterized using a current-in-plane tunneling system. Structural and physical analyses are performed using transmission electron microscopy and a superconducting quantum interference device. It is found that the sensing layer is able to exhibit a linear output and sensitivity up to 0.25% MR/Oe as the thickness of the MgO cap layer is lowered to 0.7 nm. The RA product increases as the thickness of the MgO cap layer decreases under 0.8 nm, which is attributed to oxidization of the CoFeB layer. This research provides a valuable direction to the optimization of double-interface CoFeB/MgO p-TMR and the sensor design in terms of linear magnetic field range and sensor RA product target for sensor applications.
A fast forecast method for dynamic stress of cylinders entering water
Authors: Zhang Xiangyuan , Shi Yao , Pan Guang
Published: March 2021

At present, the dynamic stress of a cylinder during water entry is generally investigated by the explicit dynamics method involving multiphases, which has a long calculation period. In this paper, a fast forecast method for dynamic stress of cylinders entering water is proposed. The water impact is replaced by an equivalent classical impact load, and the explicit dynamic analysis of multiphases is transformed into the implicit dynamic analysis of a single phase. Therefore, the dynamic stresses of cylinders can be solved rapidly and the relative errors with the results in existing literature are less than 10%. This study can be used to evaluate the dynamic stress and strength of cylindrical structures in a relatively short time.
An insight into the binding behavior of graphene oxide and noble metal nanoparticles
Authors: Saeed Wajeeha , Abbasi Zeeshan , Majeed Shumaila , Shahzad Sohail Anjum , Khan Abdul Faheem , Shaikh Ahson Jabbar
Published: March 2021

The binding behavior of graphene oxide and metal nanoparticles (Au, Pt, and Pd) was observed by UV–Vis spectroscopy, fluorescence spectroscopy, dynamic light scattering, and zeta potential. Hybrids with a fixed concentration of graphene oxide (GO) were prepared with increasing concentration of metal nanoparticles to observe the effect of binding on their spectroscopic properties, size, and zeta potential. An increase in the absorption spectra of GO after binding with nanoparticles and a gradual decrease in fluorescence emission intensity with increasing concentration of nanoparticles was observed, representing their effective binding. Stern–Volmer plots differentiated the quenching constants of these nanoparticles, where Au shows the lowest and Pd shows the highest quenching among these nanoparticles. The initial hybrids showed more size change as compared to hybrids with a higher concentration of nanoparticles, whereas initial hybrids have charge similar to that of GO and gradual increase in the concentration of nanoparticles bring the charge near to the respective charge of nanoparticles. To the best of our understanding, this is the first report of its kind to study the binding interactions of two different moieties by studying changes occurred in the hydrodynamic radius and zeta potential of hybrids by titration experiments, having applications in surface treatment, drug delivery, and as sensors for environmental pollutants or other classes of organic molecules, etc.
Order-of-magnitude laser imprint reduction using pre-expanded high-Z coatings on targets driven by a third harmonic Nd:glass laser
Authors: Karasik Max , Oh Jaechul , Obenschain S. P. , Schmitt A. J. , Aglitskiy Y. , Stoeckl C.
Published: March 2021

A hybrid early time x-ray drive followed by conventional laser direct drive obtained by utilizing a thin high-Z overcoat on plastic ablator targets has proven to be very effective at reducing laser imprint in experiments driven by the Nike krypton-fluoride laser. An inherent low level laser prepulse from that laser system heated and expanded the coating prior to the main pulse. Here, we report on results using a frequency tripled Nd:glass laser system (Omega EP) where the inherent prepulse was several orders of magnitude smaller. By applying a separate prepulse, these experiments allowed us to test if the prepulse is important for mitigating imprint with the high-Z layer. The results show that the high-Z coating is much more effective at reducing laser imprint when it is pre-expanded, in this case, by an externally generated low level soft x-ray prepulse of ∼10 J/cm2. With the x-ray prepulse, laser imprint at spatial wavelengths below 100 μm was reduced by an order of magnitude, similar to that observed with the laser prepulse on Nike. Furthermore, the experiments here establish that high-Z coating is effective in reducing imprint even in the case of a fixed speckle pattern. Rayleigh–Taylor-amplified laser imprint and high-Z layer dynamics were measured using through-foil and side-on x-ray radiography. Pre-expansion times from 30 down to 6 ns were effective, potentially compatible with laser prepulse generation using existing NIF and OMEGA front ends; however, temporal beam smoothing appears to be necessary for the laser prepulse that directly illuminates the high-Z coating. The highest imprint reduction is observed for Pd and Au coatings of at least 400 Å thickness; thicknesses down to 200 Å show a reduction in imprint with an adjusted prepulse.
Demystifying the Stern layer at a metal–electrolyte interface: Local dielectric constant, specific ion adsorption, and partial charge transfer
Authors: Wang Xuepeng , Liu Kun , Wu Jianzhong
Published: March 2021

Electric double layer (EDL) represents one of the most basic concepts in electrochemistry and is pertinent to diverse engineering applications ranging from electrocatalysis to energy storage. Whereas phenomenological and coarse-grained models have been long established to describe ionic distributions in the diffuse layer, a faithful prediction of the physicochemical properties of the electrode–electrolyte interface from a molecular perspective remains a daunting challenge. In this work, we investigate the charging behavior of an Ag (111) electrode in NaF aqueous solutions leveraging experimental results and theoretical calculations based on the classical density functional theory for ion distributions in the diffuse layer and on the joint density functional theory (JDFT) for the electronic structure. When the Ag electrode is applied with a negative voltage, the surface charge density can be reasonably described by assuming a neutral Stern layer with the dielectric constant dependent on the local electric field as predicted by the Kirkwood equation. However, the specific adsorption of F− ions must be considered when the electrode is positively charged and the fluoride adsorption can be attributed to both physical and chemical interactions. Qualitatively, F− binding and partial charge transfer are supported by JDFT calculations, which predict an increased binding energy as the voltage increases. Our findings shed insight on the molecular characteristics of the Stern layer and the charge behavior of adsorbed species not specified by conventional EDL models.
β-Ga2O3 hetero-junction barrier Schottky diode with reverse leakage current modulation and BV2/Ron,sp value of 0.93 GW/cm2
Authors: Yan Qinglong , Gong Hehe , Zhang Jincheng , Ye Jiandong , Zhou Hong , Liu Zhihong , Xu Shengrui , Wang Chenlu , Hu Zhuangzhuang , Feng Qian , Ning Jing , Zhang Chunfu , Ma Peijun , Zhang Rong , Hao Yue
Published: March 2021

In this paper, we show that high-performance β-Ga2O3 hetero-junction barrier Schottky (HJBS) diodes with various β-Ga2O3 periodic fin widths of 1.5/3/5 μm are demonstrated with the incorporation of p-type NiOx. The β-Ga2O3 HJBS diode achieves a low specific on-resistance (Ron,sp) of 1.94 mΩ cm2 with a breakdown voltage of 1.34 kV at a β-Ga2O3 periodic fin width of 3 μm, translating to a direct-current Baliga's power figure of merit (PFOM) of 0.93 GW/cm2. In addition, we find that by shrinking the β-Ga2O3 width, the reverse leakage current is minimized due to the enhanced sidewall depletion effect from p-type NiOx. β-Ga2O3 HJBS diodes with p-type NiOx turn out to be an effective route for Ga2O3 power device technology by considering the high PFOM while maintaining a suppressed reverse leakage current.
Optoelectronic superlattices based on 2D transition metal dichalcogenides
Authors: Liu Dan-Na , Guo Yong
Published: March 2021

Optoelectronic superlattices are proposed based on two-dimensional transition metal dichalcogenides, which can be realized by periodically superimposed, interlaced, or alternate modulations of the gate voltage and the off-resonant right circularly polarized light. Owing to the huge band gap and spin–orbit coupling, the propagation of electrons through the gate tunable WSe2 superlattice under the optical field becomes highly valley-dependent, i.e., the transmission and conductance are suppressed for the K valley but enhanced remarkably for the K′ valley. Moreover, it is shown that the properties of the line-type resonant peaks are extremely sensitive to the valley and spin degrees of freedom, the period number of superlattice, and the mode of modulated external fields and can be further drastically adjusted by the width of the modulated region. This work may shed light on potential applications of the optoelectronic superlattices in the fields of valleytronics and spintronics.
Engineering electron wavefunctions in asymmetrically confined quasi one-dimensional structures
Authors: Kumar S. , Pepper M. , Montagu H. , Ritchie D. , Farrer I. , Griffiths J. , Jones G.
Published: March 2021

We present results on electron transport in quasi-one dimensional quantum wires in GaAs/AlGaAs heterostructures obtained using an asymmetric confinement potential. The variation of the energy levels of the spatially quantized states is followed from strong confinement through weak confinement to the onset of two dimensionality. An anticrossing of the initial ground and first excited states is found as the asymmetry of the potential is varied, giving rise to two anticrossing events, which occur on either side of symmetric confinement. We present results analyzing this behavior and showing how it can be affected by the inhomogeneity in background potential. The use of an enhanced source-drain voltage to alter the energy levels is shown to be a significant validation of the analysis by showing the formation of double rows of electrons, which correlate with the anticrossing.
Quantum reactive scattering calculations for the cold and ultracold Li + LiNa → Li2 + Na reaction
Authors: Kendrick Brian K.
Published: March 2021

A first-principles based quantum dynamics study of the Li + LiNa(v = 0, j = 0) → Li2(v′, j′) + Na reaction is reported for collision energies spanning the ultracold (1 nK) to cold (1 K) regimes. A full-dimensional ab initio potential energy surface for the ground electronic state of Li2Na is utilized that includes an accurate treatment of the long-range interactions. The Li + LiNa reaction is barrierless and exoergic and exhibits a deep attractive potential well that supports complex formation. Thus, significant reactivity occurs even for collision temperatures approaching absolute zero. The reactive scattering calculations are based on a numerically exact time-independent quantum dynamics methodology in hyperspherical coordinates. Total and rotationally resolved rate coefficients are reported at 56 collision energies and include all contributing partial waves. Several shape resonances are observed in many of the rotationally resolved rate coefficients and a small resonance feature is also reported in the total rate coefficient near 50 mK. Of particular interest, the angular distributions or differential cross sections are reported as a function of both the collision energy and scattering angle. Unique quantum fingerprints (bumps, channels, and ripples) are observed in the angular distributions for each product rotational state due to quantum interference and shape resonance contributions. The Li + LiNa reaction is under active experimental investigation so that these intriguing features could be verified experimentally when sufficient product state resolution becomes feasible for collision energies below 1 K.
Thermochemistry of the Ir+ + SO2 reaction using guided ion beam tandem mass spectrometry and theory
Authors: Kim JungSoo , Armentrout P. B.
Published: March 2021

Kinetic energy dependences of the reactions of Ir+ (5F5) with SO2 were studied using a guided ion beam tandem mass spectrometer and theory. The observed cationic products are IrO+, IrS+, and IrSO+, formed in endothermic reactions. Bond dissociation energies (BDEs) of the products are determined by modeling the kinetic energy dependent product cross sections: D0(Ir+–O) = 4.27 ± 0.11 eV, D0(Ir+–S) = 4.03 ± 0.06 eV, and D0(Ir+–SO) ≥ 2.95 ± 0.06 eV. The oxide BDE agrees well with literature values, whereas the two latter results are novel measurements. Quantum mechanical calculations are performed at the B3LYP level of theory using the def2-TZVPPD basis set for all product BDEs with additional calculations for IrS+, IrO2+, and IrSO+ at the coupled cluster with single, double, and perturbative triple excitation levels with def2-QZVPPD and aug-cc-pVXZ (X = T and Q and for IrS+, also X = 5) basis sets and complete basis set extrapolations. These theoretical BDEs agree reasonably well with the experimental values. 1A1 (IrO2+), 5Δ4 (IrS+), and 3A″/1A′ (IrSO+) are found to be the ground states after including empirical spin–orbit corrections. The potential energy surfaces including intermediates and transition states for each reaction are also calculated at the B3LYP/def2-TZVPPD level. The formation of MO+ (M = Re, Os, and Ir) from M+ + SO2 reactions is compared with those from the M+ + O2 and M+ + CO reactions, where interesting trends in cross sections are observed. Overall, these studies suggest that the M+ + O2 reactions had restrictions associated with reactions along A′ and A″ surfaces.
Multi-phase simulation of infected respiratory cloud transmission in air
Authors: De Padova Diana , Mossa Michele
Published: March 2021

In the face of the increasing death toll of the COVID-19 global pandemic, countries around the world have instituted restrictive measures to mitigate the serious effects of the pandemic. Human-to-human transmission of COVID-19 occurs primarily through large droplets that are expelled with sufficient momentum to come in direct contact with the recipients’ mouth. Therefore, the physics of flow is central to transmission of COVID-19. Respiratory infections increase the frequency of violent expiration, including coughing and sneezing that are particularly effective in dispersing virus-carrying droplets. Moreover, the high viral load in droplets of asymptomatic hosts that are expelled during respiratory activities is contributing to the rapid growth of the COVID-19 global pandemic. The present study uses 2D smoothed-particle-hydrodynamics multi-phase simulations of the fluid dynamics of violent expiratory events in order to obtain a deeper understanding of the multi-phase nature of respiratory clouds, which can help determine separation distances from an infected person needed to minimize respiratory transmission. Our results indicate that there are three phases of jet cloud flow: the first is dominated by no-buoyancy jet-like dynamics characterized by a high speed, the second is dominated by negative buoyancy, and the third is dominated by gravity that deflects the cloud downward. Moreover, two modes of jet behavior that differ in dilution have been identified to be a function of distance from the human mouth. This work is of direct relevance to studies on the spread of COVID-19 and similar outbreaks in the future.
Effect of dietary inclusion of yellow mealworm (
Authors: Sedgh-Gooya Shadi , Torki Mehran , Darbemamieh Maryam , Khamisabadi Hassan , Abdolmohamadi Alireza
Published: March 2021

Abstract Context Increasing demand for animal products, and scarcity and cost of conventional feed ingredients, drive the search for alternative energy and protein sources for poultry feed. Insects provide opportunities as a sustainable, high-quality and low-cost component of poultry feed. Aims This study evaluated the effects of dietary inclusion of powdered Tenebrio molitor (yellow mealworm) larvae meal on productive performance, egg quality characteristics and blood parameters of laying hens. Methods In total, 126 Bovans White laying hens, 63 weeks of age, were allocated to three dietary groups, each with seven replicate cages of six birds per cage. Treatments were: a basal diet, and two experimental diets comprising the basal diet plus T. molitor larvae meal at 2.5% or 5% inclusion rate. The duration of the study was 8 weeks. Key results Egg production, egg mass and feed conversion ratio were all improved (P < 0.05) by inclusion of T. molitor meal in the diet. The lower rate of inclusion was more effective with respect to egg production and feed conversion ratio. Inclusion of larvae meal did not influence (P > 0.05) feed intake, egg weight or bodyweight gain. Furthermore, egg quality characteristics and blood parameters were not influenced (P > 0.05) by dietary treatment. Conclusions The study showed that inclusion of T. molitor larvae meal in the diet of laying hens could improve productive performance, especially at the 2.5% level. Implications Powdered meal of T. molitor larvae is an appropriate, unconventional feed ingredient for laying hens, and may have a role in improving socioeconomic and environmental outcomes, aligning with the United Nations’ sustainable development goals.
Overheating turns a bat box into a death trap
Authors: Griffiths Stephen R.
Published: March 2021

Thirty juvenile large forest bats (Vespadelus darlingtoni) were found dead in a plywood bat box. This is the first example in Australia of an overheating event in a bat box resulting in multiple mortalities. It confirms that extreme heat in poorly insulated bat boxes can result in acute hyperthermia.
Mad dephosphorylation at the nuclear pore is essential for asymmetric stem cell division
Authors: Sardi Justin , Bener Muhammed Burak , Simao Taylor , Descoteaux Abigail E. , Slepchenko Boris M. , Inaba Mayu
Published: March 2021

Significance

Stem cells often divide into two different cell types: stem cells and differentiating cells. This phenomenon, called “asymmetric cell division,” is important for balancing the number of these two cell populations. Here, we demonstrate that phosphorylated Mad (pMad), the immediate downstream molecule of the niche signal, is asymmetrically partitioned within a dividing stem cell before the completion of cytokinesis. We identified a known Mad phosphatase, Dullard, as an essential factor for this process. Mathematical modeling recapitulates high sensitivity of the ratio of pMad levels to the Mad phosphatase activity and explains how the early asymmetry arises in a shared cytoplasm.
The producer benefits of implicit fossil fuel subsidies in the United States
Authors: Kotchen Matthew J.
Published: March 2021

Significance

There are real and substantial financial implications to fossil fuel producers of policies that seek to correct market failures brought about by climate change, adverse health effects from local pollution, and inefficient transportation. The producer benefits of the existing policy regime in the United States are estimated at $62 billion annually during normal economic conditions. This translates into large amounts for individual companies due to the relatively small number of fossil fuel producers. This paper provides company-specific estimates, and these numbers clarify why many in the fossil fuel industry oppose more efficient regulatory reform; they may also shape the way policymakers view the prospects for additional subsidies going forward.