bluuebunny/crossref_metadata_2025 huggingface dataset:
Cholangioscopy: Has It Changed Management?
Authors: Dhar Chowdhury Sudipta , Jaleel Rajeeb
Published: April 2022

The single operator per oral cholangioscope is a catheter-based system that allows for direct visualization of the bile duct and pancreatic duct. The instrument with its improved imaging technique and larger accessory channel allows for high-quality image acquisition and performance of therapeutic and diagnostic procedures within the bile duct and pancreatic duct. There has been an increase in the range of indications for the use of the cholangioscope. The current indications include management of difficult biliary stones, pancreatic calculi, assessment of indeterminate biliary stricture, pancreatic stricture, intra-ductal papillary mucinous neoplasms, and extractions of proximally migrated stents. The use of laser lithotripsy and electro-hydraulic lithotripsy has improved the management of difficult bile duct stones. Direct visualization of biliary and pancreatic duct strictures is helpful in the diagnosis of indeterminate strictures. In this review, we explore how cholangioscopy has changed management.
Quality of Life Post Breast Cancer Surgery: Comparison of Breast Conservation Surgery versus Modified Radical Mastectomy in a Developing Country
Authors: Cherian Kurian , Acharya Nitish Rajan , Bhargavan Rexeena V. , Augustine Paul , Krishnan Jagathnath K.M.
Published: April 2022

Introduction Breast cancer survivors are the largest group of female cancer survivors. Oncologic breast surgery can have a profound impact on a woman's body image and sense of self that can significantly affect their quality of life (QOL). The paucity of data about the effect of type of surgery on QOL of Indian breast cancer survivors has led to this study.

Materials and Methods This prospective study included consecutive female early breast cancer patients who underwent primary surgery, that is, breast conservation surgery (BCS) or modified radical mastectomy (MRM) from January 1, 2015 to December 31, 2015. The primary objective was the comparison of QOL using European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and EORTC QLQ-BR 23 between the two groups at 6 months and 1 year postsurgery with the baseline.

Results One hundred and thirty-eight patients were included of which 62 underwent BCS and 76 underwent MRM. BCS patients fared better with respect to physical functioning, dyspnea, fatigue, appetite loss, and body image at 6 months (p < 0.05) as compared with MRM. At 1 year postsurgery, BCS patients fared better with respect to physical functioning, role functioning, global health status, body image, sexual enjoyment, and dyspnea, while MRM patients fared better in emotional functioning and future prospectives (p < 0.05).

Conclusion Patients undergoing BCS have a better QOL with respect to various functional and symptom scales at 6 months and 1 year. However, patients undergoing MRM perform better in terms of future perspective and emotional functioning at 1 year.
Concurrent Weekly Cisplatin and Simultaneous Integrated Boost-IMRT in Locally Advanced Head and Neck Squamous Cell Carcinoma—An Institutional Experience
Authors: Ahmed Imtiaz , Krishnamurthy Sapna , Bhise Rohan , Vinchurkar Kumar , Kalloli Mahesh
Published: April 2022

Introduction Concurrent chemoradiation with weekly cisplatin in locally advanced head and neck squamous cell carcinoma (LA-HNSCC) is widely practiced in India. Radiation with simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) has the advantage of executing IMRT in single phase with better dose distribution.

Material and Methods 150 patients with LA-HNSCC treated between April 2015 and December 2019 were retrospectively evaluated. All patients received 70Gy in 33 to 35 fractions with SIB-IMRT and concurrent weekly cisplatin at a dose of 40 mg/m2. Treatment compliance and toxicities were assessed. Overall survival (OS) was evaluated using Kaplan-Meier estimates; univariate and multivariate analysis of prognostic factors were also evaluated.

Results Median age was 58.5 years. Forty-five percent had primary oropharyngeal cancer. Sixty-two percent had T3 disease, 41% had N2 disease, and 51% had stage IV disease. All patients received 70Gy dose of RT. Median chemotherapy cycles were six, 84.7% received 200 mg/m2. Acute grade 2 xerostomia was seen in 79%, grade 3 neutropenia, mucositis and pharyngitis were seen in 11, 15, and 21%, respectively. Complete response was seen in 66.6%. At median follow-up of 21.4 months (3–71) OS was 60% and median OS was 33.2 months. Estimated 2 and 3 year OS was 56 and 48%. On univariate analysis, absence of node, N0–N1, stage III, cisplatin use, dose per fraction 2.12Gy ,and complete response showed good OS (p <0.05). On multivariate analysis dose per fraction 2.12Gy and complete response showed good OS (p <0.05).

Conclusion Definitive chemoradiation with weekly cisplatin and SIB-IMRT in LA-HNSCC is well tolerated with good clinical outcomes.
Diagnosis and Management of Preeclampsia: Suggested Guidance on the Use of Biomarkers
Authors: Costa Maria Laura , Cavalli Ricardo de Carvalho , Korkes Henri Augusto , Cunha Filho Edson Vieira da , Peraçoli José Carlos
Published: April 2022

Objective It is a challenge to consider preeclampsia (PE) diagnosis and management in low and middle-income settings, where it represents a major public health concern. The placenta is the underlying cause of disease, and the plasma concentrations of proangiogenic and antiangiogenic factors released by the placenta can reflect the risks of disease progression. Antiangiogenic proteins, such as soluble fms-like tyrosine kinase 1 (sFlt-1), and proangiogenic, like placental growth factors (PlGF), are directly and inversely correlated with the disease onset, respectively.

Methods Narrative review on the use of biomarkers (sFlt-1 to PlGF ratio) with a suggested guidance protocol.

Results Key considerations on the use of biomarkers: the sFlt-1/PlGF ratio is mainly relevant to rule out PE between 20 and 36 6/7 weeks in cases of suspected PE; however, it should not replace the routine exams for the diagnosis of PE. The sFlt-1/PlGF ratio should not be performed after confirmed PE diagnosis (only in research settings). In women with suspected PE, sFlt-1/PlGF ratio < 38 can rule out the diagnosis of PE for 1 week (VPN = 99.3) and up to 4 weeks (VPN= 94.3); sFlt-1/PlGF ratio > 38 does not confirm the diagnosis of PE; however, it can assist clinical management. In cases of severe hypertension and/or symptoms (imminent eclampsia), hospitalization is imperative, regardless of the result of the sFlt-1/PlGF ratio.

Conclusion The use of biomarkers can help support clinical decisions on the management of suspected PE cases, especially to rule out PE diagnosis, thus avoiding unnecessary interventions, especially hospitalizations and elective prematurity
Diagnosis and Management of Acute and Chronic Portomesenteric Venous Thrombosis
Authors: Ferral Hector
Published: April 2022

Thrombosis of the portal and mesenteric veins is relatively uncommon. Thrombosis can be acute or chronic. Management is dictated by symptoms on clinical presentation. Acute symptomatic mesenteric vein thrombosis may require aggressive endovascular intervention with mechanical thrombectomy, thromboaspiration, infusion of thrombolytic drugs, TIPS creation or surgery. Chronic, symptomatic portal and mesenteric vein thrombosis usually requires recanalization of occluded segments and stent placement. The three main catheterization techniques for access into the portal venous system are: transhepatic, transjugular and trans-splenic. Evidence-based therapeutic strategies for acute and chronic portal and mesenteric vein thrombosis have not been established. There are no prospective comparative studies to support superiority of any given technique in the management of these conditions. The purpose of this review is to present an overview of the etiology, physiopathology, clinical presentation, and management of acute and chronic portal and mesenteric vein thrombosis.
Modeling prey behavior in response to fear of predation
Authors: Thompson Avery
Published: April 2022

Fractional-order differential equations allow for a more detailed and accurate model of prey-predator system
Cross-beam energy transfer in direct-drive ICF. I. Nonlinear and kinetic effects
Authors: Seaton A. G. , Yin L. , Follett R. K. , Albright B. J. , Le A.
Published: April 2022

Results are presented from a series of simulations examining the susceptibility of the cross-beam energy transfer (CBET) instability to nonlinear processes in the context of direct-drive inertial confinement fusion experiments on the OMEGA laser facility. These form the basis for the second paper of this series [A. G. Seaton, L. Yin, R. Follett, B. J. Albright, and A. Le, “Cross-beam energy transfer in direct-drive ICF. II. Theory and simulation of mitigation through increased laser bandwidth,” Phys. Plasmas 29, 042707 (2022)], where we examine the efficacy of increases in laser bandwidth at suppressing CBET. We choose laser and plasma conditions for the simulations that are favorable to CBET and promote nonlinearity. Through a comparison of outputs from the particle-in-cell code vector particle in cell (VPIC) and the linearized fluid code laser-plasma simulation environment (LPSE), a series of nonlinear effects have been identified in the kinetic simulations that include particle trapping, the two-ion wave decay, and ion-acoustic wave self-focusing. These effects produce time-dependent energy transfer, in contrast to the linearized fluid simulations in which a steady state is reached after an initial transient. Ion trapping is shown to allow for increased energy transfer relative to fluid simulations, with the remaining nonlinear processes acting to reduce the energy transfer. Nonlinear dynamics is contrasted for low- and high-intensity beams as well as between speckled and planar beams. For the parameters under consideration, beam profile has a significant effect on nonlinear dynamics, though the greatest sensitivity is to beam intensity.
Development and tuning of the microwave resonant cavity of a cryogenic cesium atomic fountain clock
Authors: Yang Fan , Wang Xinliang , Fan Sichen , Bai Yang , Shi Junru , Liu Dandan , Zhang Hui , Guan Yong , Hao Qiang , Ruan Jun , Zhang Shougang
Published: April 2022

A cryogenic cesium atomic fountain clock is a novel clock with the microwave cavity and atomic free flight region placed in liquid nitrogen. On the one hand, the blackbody radiation shift is reduced at cryogenic temperature. On the other hand, the vacuum in the atomic free flight region is optimized, and the background gas collision shift reduced. The microwave resonant cavity is the most important unit in a cryogenic cesium atomic fountain clock. Through theoretical and simulative investigation, this study designs the configuration and dimensions for an optimized microwave cavity. Concurrently, experiments reveal the effects of temperature, pressure, humidity, and other factors on the resonant frequency of the microwave cavity. Combining the theoretical and experimental study, we obtain the resonant frequency difference between the microwave cavity in a cryogenic vacuum and at room temperature and ambient pressure. By subtracting this frequency difference, we adjust the microwave cavity for room temperature and ambient pressure, then vacuumize and immerse it in liquid nitrogen for verification and fine tuning. Finally, we determine that the microwave cavity resonant frequency deviation from the clock transition frequency is 10 kHz with an unloaded quality factor of 25 000, which meets the application requirements of the cryogenic cesium atomic fountain clock.
Enhanced performance of supercapacitors based on rotationally stacked CVD graphene
Authors: Ibrahim W. Lisheshar , Şar Hüseyin , Ay Feridun , Kosku Perkgöz Nihan
Published: April 2022

One of the main problems faced by 2D materials used in supercapacitor applications when scaling up is restacking, such that their gravimetric capacitances become dramatically inferior to that of their monolayer forms. This study analyzes the Raman spectra of transferred layers of CVD-graphene revealing decoupling and rotational stacking of layers, with the potential of retention of intrinsic monolayer properties. Rotationally stacked layers have the potential to mitigate restacking and, thus, are capable of easing ion intercalation and boosting their performance in supercapacitor applications. In this pursuit, binder-free supercapacitors are fabricated out of chemical vapor deposited bilayer graphene, successively transferred to form rotationally stacked multilayers. Supercapacitors constructed with rotationally stacked four-layer graphene have an incredible specific gravimetric capacitance of 316.1 F g−1 at 1 mV s−1, with a corresponding energy density of 28.1 Wh kg−1 and ∼100% capacitance retention at 10 000 cycles.
Realizing single-mode lasing in all-inorganic CsPbBr3 perovskite microwires using intrinsic self-absorption
Authors: Lu Junfeng , Zhang Chengyu , Li Fangtao , Wang Ru , Qin Feifei , Zhu Gangyi
Published: April 2022

Single-mode operation while maintaining a high-quality factor have always been key factors for building high-performance semiconductor lasers. Here, single CsPbBr3 perovskite microwire with a width of ∼3 μm is served as an active microresonator in which a typical single-mode laser output with a quality factor of 3000 is realized through the intrinsic self-absorption effect in success. Simultaneously, we observed the evolution of cavity modes in different dimensional perovskite microresonators and discussed the internal mechanisms of mode evolution and single-mode output in depth. The synergistic effect of intrinsic self-absorption and cavity size is the dominant factor for single-mode lasing output. It provides a feasible approach for the subsequent construction of high-quality electrically pumped single-mode lasers.
Generation of intense sub-cycle terahertz pulses with variable elliptical polarization
Authors: Ropagnol X. , lsgandarov E. , Chai X. , M. Raeis-Zadeh S. , Safavi-Naeini S. , Reid M. , Blanchard F. , Ozaki T.
Published: April 2022

We demonstrate the generation of intense, sub-cycle terahertz (THz) pulses with variable elliptical polarization and peak fields above 80 kV/cm from large aperture photoconductive antennas using a specific interdigitated structure. The latter is composed of horizontal and vertical electrodes, which allow the generation of two quasi-half-cycle THz pulses with orthogonal polarization. A time delay between the two THz pulses is introduced by a phase delay mask covering only the parts of the antenna with horizontal electrodes. By changing the mask thicknesses, we can control, on demand, the polarization state of the THz pulses from linear polarization through elliptical to circular polarization over a quarter of a THz cycle.
Elliptical-tube off-beam quartz-enhanced photoacoustic spectroscopy
Authors: Shang Zhijin , Wu Hongpeng , Li Shangzhi , Tittel Frank K. , Dong Lei
Published: April 2022

We propose an elliptical-tube off-beam quartz-enhanced photoacoustic spectroscopy (EO-QEPAS) method in which an elliptical tube is employed as an acoustic resonator, instead of a circular resonator in QEPAS, to match the stripe-like beam emitted from a high-power multimode laser diode (MLD). A lower noise level than that of conventional QEPAS is achieved due to the optimal matching between the elliptical resonator and the beam profile, hence resulting in a ∼3 times higher signal-to-noise ratio gain factor compared with the circular resonator. The parameters of the elliptical resonator are optimized, and a 1σ normalized noise equivalent absorption coefficient of 3.4 × 10−8 cm−1 W/Hz1/2 is obtained for dry NO2 detection at normal atmospheric pressure. EO-QEPAS paves the way for developing compact, cost-effective, and highly sensitive gas sensors based on the combination of MLDs and QEPAS.
Rashba spin–orbit interaction effect in twisted silicon nanotubes for chiral spintronics
Authors: D'yachkov Pavel N. , D'yachkov Evgeny P.
Published: April 2022

Using a relativistic symmetrized linear augmented cylindrical wave method, we investigated a formation of spin minigaps due to a torsion strain of the nonchiral hexagonal and gear-like armchair (n, n) and zigzag (n, 0) silicon nanotubes (SiNTs). In the absence of mechanical twisting, the hexagonal (n, n) SiNTs have an inversion symmetry and metallic band structures with the spin-degenerate states at the Fermi region. The torsion deformation of hexagonal armchair SiNT breaks the inversion symmetry, transforming it into the chiral system with the right or left screw axis. Due to the combined effect of spin–orbit coupling and low-symmetry perturbation, the degeneration of levels is completely removed and the α and β type bands are formed. The torsion deformation works like a switch, the opposite twisting directions result in the opposite chirality of tubules and induce the opposite spin currents due to Rashba effect. Even in the ideal non-twisted gear-like SiNTs, there is no inversion symmetry. Such tubules have semiconductor band structures with the spin–orbit splittings of the valence and conduction bands. Twisting causes an increase in the antisymmetric component of the potential leading to a monotonic increase in the spin gaps.
Tracking moving target for 6 degree-of-freedom robot manipulator with adaptive visual servoing based on deep reinforcement learning PID controller
Authors: Wang Fei , Ren Baiming , Liu Yue , Cui Ben
Published: April 2022

In this paper, an image-based visual servoing (IBVS) controller with a 6 degree-of-freedom robotic manipulator that tracks moving objects is investigated using the proposed Deep Q-Networks and proportional–integral–derivative (DQN-PID) controller. First, the classical IBVS controller and the problem of feature loss and large steady-state error for tracking moving targets are introduced. Then, a DQN-PID based IBVS method is proposed to solve the problem of feature loss and large steady-state error and improve the servo precision, as the existing methods are hard to use for solve the problems. Specifically, the IBVS method is inherited by our controller to build the tracking model, and a value-based reinforcement learning method is proposed as an adaptive law for dynamically tuning the PID parameters in the discrete space, which can track the moving target and keep the servo feature in the field of the camera. Finally, compared with the different existing methods, the DQN-PID based IBVS method has merits of higher accuracy and more stable tracking, or generalization.
Regulation of energy band and luminescence properties in blue quasi-2D lead bromide perovskite via lattice strain
Authors: Cao Chunyue , Lu Yao , Li Huitian , Song Dandan , Zhao Suling , Xu Zheng , Smirnov Aliaksandr , Qiao Bo
Published: April 2022

Development of blue quasi-2D lead halide perovskite LEDs is key to the perovskite based full-color displays and white-light illumination. It is still quite challenging to accurately enlarge the bandgap to achieve high performance and stable blue Quasi-2D perovskite LEDs. The lattice strain due to the deformation of lead-bromide octahedra is a critical factor leading to the energy band adjustment and stability optimization. In this Letter, the lattice strain is adjusted via three cations with different sizes, Cs+, CH3CH2NH2+ (EA+), and Rb+, for sophisticatedly micro-tuning of the lattice strain to achieve overall lattice expansion and lattice contraction. A ternary quasi-2D blue bromide perovskite material PEA2(CsxEAyRb1-x-yPbBr3)2PbBr4 is specially designed. The crystal structure and energy band are studied by the first principles calculations using the Density Functional Theory method. The luminescence properties of blue quasi-2D lead bromide perovskite materials are analyzed with spectra regulation from 508 to 464 nm for photoluminescence and from 510 to 470 nm for electroluminescence. The thermal treatment is used to accelerate the release of residual strain due to mismatch and disorder in the lattice, leading to defects and degradation. The lattice strain is strongly correlated with the energy band, luminescence performance, and thermal stability of blue quasi-2D lead bromide perovskite. The study of lattice strain relaxation in blue quasi-2D lead bromide perovskite could open avenues for high-performance and stable blue quasi-2D perovskite LEDs.
Temperature induced change of TMAO effects on hydrophobic hydration
Authors: Folberth Angelina , van der Vegt Nico F. A.
Published: April 2022

The effect of trimethylamine-N-oxide (TMAO) on hydrophobic solvation and hydrophobic interactions of methane has been studied with Molecular Dynamics simulations in the temperature range between 280 and 370 K at 1 bar ambient pressure. We observe a temperature transition in the effect of TMAO on the aqueous solubility of methane. At low temperature (280 K), methane is preferentially hydrated, causing TMAO to reduce its solubility in water, while above 320 K, methane preferentially interacts with TMAO, causing TMAO to promote its solubility in water. Based on a statistical-mechanical analysis of the excess chemical potential of methane, we find that the reversible work of creating a repulsive methane cavity opposes the solubility of methane in TMAO/water solution more than in pure water. Below 320 K, this solvent-excluded volume effect overcompensates the contribution of methane–TMAO van der Waals interactions, which promote the solvation of methane and are observed at all temperatures. These van der Waals interactions with the methyl groups of TMAO tip the balance above 320 K where the effect of TMAO on solvent-excluded volume is smaller. We furthermore find that the effective attraction between dissolved methane solutes increases with the increasing TMAO concentration. This observation correlates with a reduction in the methane solubility below 320 K but with an increase in methane solubility at higher temperatures.
Magnetic properties and coercivity mechanism of high Ce-content CeNdFeB film with Tb diffusion
Authors: Wu J. X. , Zhao X. T. , Liu W. , Li Y. , Ma J. , Song Y. H. , Liu L. , Ju H. Z. , Zhang Z. D.
Published: April 2022

Magnetic properties and coercivity mechanism of an anisotropic Ce–Nd–Fe–B film with a high Ce content (70 at. % Nd is replaced by Ce) have been investigated. After grain boundary diffusion with Tb layers, an enhancement of coercivity from 4150 to 9250 Oe is observed. Combining the initial magnetization curves, micromagnetic theory, and in-siut observation of magnetic domains in the demagnetization process, it is confirmed that the coercivity mechanism for the high-Ce-content magnets is the mixed type dominated by the pinning mechanism. Moreover, as the thickness of the Tb diffusion layer increases, the pinning center of domain walls changes from narrow planar inhomogeneities to wide planar inhomogeneities. A growing role of pinning plays in determining the coercivity of samples with increasing the thickness of Tb layer due to the increase in magnetocrystalline anisotropy after Tb substitution in the RE2Fe14B phase. In addition, the CeFe2 intergranular phase leads to the enhancement of coercivity due to decoupling the hard magnetic phase grains. Our results provide an insight into the coercivity mechanism of high-Ce-concentration Ce–Nd–Fe–B magnetic materials and promote the comprehension of the effect of Tb diffusion in the magnetization reversal process.
AlN/GaN/InGaN coupling-channel HEMTs with steep subthreshold swing of sub-60 mV/decade
Authors: Lu Hao , Yang Ling , Hou Bin , Zhang Meng , Wu Mei , Ma Xiao-Hua , Hao Yue
Published: April 2022

This work reports an AlN/GaN/InGaN high electron mobility transistor (HEMT) with a steep subthreshold swing (SS) of sub-60 mV/dec utilizing a coupling-channel architecture. The fabricated transistors show a negligible hysteresis, a SS of 39 mV/dec, a large gate voltage swing of >4.2 V, and achieving an excellent quality factor Q = gm/SS of 6.3 μS-dec/μm-mV. The negative differential resistance effect was found in the subthreshold region in the gate current–voltage (Ig–VGS) curve. The hot carrier transfer mechanism that occurred in the turn-on/pinch-off progress of the CC-HEMT under the dual-directional sweep, proved by the VDS- and Lg-dependent bi-directional transfer I–V characteristics, can be responsible for these excellent device performances. This work is believed to encourage further study of the AlN/GaN platform to power the future group III-nitrides CMOS technology.
Critical electric field for transition of thermionic field emission/field emission transport in heavily doped SiC Schottky barrier diodes
Authors: Hara Masahiro , Tanaka Hajime , Kaneko Mitsuaki , Kimoto Tsunenobu
Published: April 2022

In this study, n-type SiC Schottky barrier diodes (SBDs) with various doping concentrations (Nd=4×1015–1×1019cm−3) were fabricated, and their forward and reverse current–voltage (I–V) characteristics were analyzed focusing on tunneling current. Numerical calculation with the fundamental formula of tunneling current gives good agreement with experimental forward and reverse I–V curves in the heavily doped SiC SBDs (Nd>2×1017cm−3). The analysis of the energy where electron tunneling most frequently occurs revealed that field emission (FE) tunneling dominates conduction instead of thermionic field emission (TFE) under a higher electric field in reverse-biased heavily doped SiC SBDs, while forward I–V characteristics are described only by TFE. In addition, the critical electric field for the TFE–FE transition is quantitatively clarified by carefully considering the sharply changing electric field distribution in SiC with a high donor concentration.
Simultaneously realized large low-temperature magnetocaloric effect and good mechanical properties in Ni36Co13Mn35Ti16 alloy
Authors: Guan Ziqi , Bai Jing , Zhang Yu , Gu Jianglong , Liang Xinzeng , Zhang Yudong , Esling Claude , Zhao Xiang , Zuo Liang
Published: April 2022

In this work, we present the observation of large low-temperature magnetocaloric effect and good mechanical properties in the Ni36Co13Mn35Ti16 alloy. The phase transition behaviors, magnetocaloric effect, and mechanical properties for the Ni36Co13Mn35Ti16 non-textured polycrystalline alloy were systematically investigated. Under the magnetic field changes of 5 T, a typical meta-magnetic behavior with a large magnetization change of about 110 A m2 kg−1 between the austenite and martensite can be observed, the maximum magnetic entropy changes (ΔSm) of the Ni36Co13Mn35Ti16 alloy is ∼16.1 J kg−1 K−1 at 148 K. Furthermore, the maximum compressive stress and strain are 894 MPa and 8.0%, respectively. The scanning electron microscope and first-principles calculations were used to analyze the fracture mechanism and the bonding interaction. In the combination of the large low-temperature magnetocaloric effect and good mechanical properties, the Ni36Co13Mn35Ti16 alloy has a good prospect for low-temperature magnetic refrigeration applications.
Fluorographene with impurities as a biomimetic light-harvesting medium
Authors: Sláma Vladislav , Rajabi Sayeh , Mančal Tomáš
Published: April 2022

We investigate the prospect of using a two-dimensional material, fluorographene, to mimic the light-harvesting function of natural photosynthetic antennas. We show by quantum chemical calculations that isles of graphene in a fluorographene sheet can act as quasi-molecules similar to natural pigments from which the structures similar in function to photosynthetic antennas can be built. The graphene isles retain enough identity so that they can be used as building blocks to which intuitive design principles of natural photosynthetic antennas can be applied. We examine the excited state properties, stability, and interactions of these building blocks. Constraints put on the antenna structure by the two-dimensionality of the material as well as the discrete nature of fluorographene sheet are studied. We construct a hypothetical energetic funnel out of two types of quasi-molecules to show how a limited number of building blocks can be arranged to bridge the energy gap and spatial separation in excitation energy transfer. Energy transfer rates for a wide range of the system–environment interaction strengths are predicted. We conclude that conditions for the near unity quantum efficiency of energy transfer are likely to be fulfilled in fluorographene with the controlled arrangement of quasi-molecules.
Modeling temperature, frequency, and strain effects on the linear electro-optic coefficients of ferroelectric oxides
Authors: Liu Yang , Ren Guodong , Cao Tengfei , Mishra Rohan , Ravichandran Jayakanth
Published: April 2022

An electro-optic modulator offers the function of modulating the propagation of light in a material with an electric field and enables a seamless connection between electronics-based computing and photonics-based communication. The search for materials with large electro-optic coefficients and low optical loss is critical to increase the efficiency and minimize the size of electro-optic devices. We present a semi-empirical method to compute the electro-optic coefficients of ferroelectric materials by combining first-principles density-functional theory calculations with Landau–Devonshire phenomenological modeling. We apply the method to study the electro-optic constants, also called Pockels coefficients, of three paradigmatic ferroelectric oxides: BaTiO3, LiNbO3, and LiTaO3. We present their temperature-, frequency-, and strain-dependent electro-optic tensors calculated using our method. The predicted electro-optic constants agree with the experimental results, where available, and provide benchmarks for experimental verification.
Understanding the chemical bonding of ground and excited states of HfO and HfB with correlated wavefunction theory and density functional approximations
Authors: Ariyarathna Isuru R. , Duan Chenru , Kulik Heather J.
Published: April 2022

Knowledge of the chemical bonding of HfO and HfB ground and low-lying electronic states provides essential insights into a range of catalysts and materials that contain Hf–O or Hf–B moieties. Here, we carry out high-level multi-reference configuration interaction theory and coupled cluster quantum chemical calculations on these systems. We compute full potential energy curves, excitation energies, ionization energies, electronic configurations, and spectroscopic parameters with large quadruple-ζ and quintuple-ζ quality correlation consistent basis sets. We also investigate equilibrium chemical bonding patterns and effects of correlating core electrons on property predictions. Differences in the ground state electron configuration of HfB(X4Σ−) and HfO(X1Σ+) lead to a significantly stronger bond in HfO than HfB, as judged by both dissociation energies and equilibrium bond distances. We extend our analysis to the chemical bonding patterns of the isovalent HfX (X = O, S, Se, Te, and Po) series and observe similar trends. We also note a linear trend between the decreasing value of the dissociation energy (De) from HfO to HfPo and the singlet–triplet energy gap (ΔES–T) of the molecule. Finally, we compare these benchmark results to those obtained using density functional theory (DFT) with 23 exchange–correlation functionals spanning multiple rungs of “Jacob’s ladder.” When comparing DFT errors to coupled cluster reference values on dissociation energies, excitation energies, and ionization energies of HfB and HfO, we observe semi-local generalized gradient approximations to significantly outperform more complex and high-cost functionals.
Three-dimensional direct numerical simulation of Rayleigh–Taylor instability triggered by acoustic excitation
Authors: Sengupta Aditi , Sundaram Prasannabalaji , Suman Vajjala K. , Sengupta Tapan K.
Published: April 2022

Rayleigh–Taylor instability (RTI) occurs when the interface between two fluids of different densities is removed, with the heavier (cold) fluid resting on top of the lighter (hot) fluid in the equilibrium state. This arrangement is unstable due to buoyancy, in the absence of any other forces. RTI is noted across a range of length scales from very small in nuclear fusion to supernova explosion at astrophysical scales. RTI is viewed as a baroclinic instability if viscous actions are ignored. An accurate non-overlapping parallel algorithm is used to solve a three-dimensional RTI problem, employing more than 4 × 109 points and a refined time step (7.69×10−8s) for the direct numerical simulation. Air masses at two different temperatures are initially separated by a non-conducting partition inside a box (with a temperature difference of 200 K). The impermeable partition is removed impulsively at t = 0, and the ensuing instability is triggered by an acoustic mechanism involving infra to ultrasonic pulses that travel to either side of the interface. Present high precision petascale computations enable one to capture acoustic disturbances with unprecedented accuracy without any additional interfacial disturbances. The creation of the vorticity is studied by performing enstrophy budget for the compressible flow for RTI, which shows that the viscous terms are dominant compared to the baroclinic one.
Revealing the exotic structure of molecules in strong magnetic fields
Authors: Pemberton Miles J. , Irons Tom J. P. , Helgaker Trygve , Teale Andrew M.
Published: April 2022

A novel implementation for the calculation of molecular gradients under strong magnetic fields is employed at the current-density functional theory level to optimize the geometries of molecular structures, which change significantly under these conditions. An analog of the ab initio random structure search is utilized to determine the ground-state equilibrium geometries for Hen and CHn systems at high magnetic field strengths, revealing the most stable structures to be those in high-spin states with a planar geometry aligned perpendicular to the field. The electron and current densities for these systems have also been investigated to develop an explanation of chemical bonding in the strong field regime, providing an insight into the exotic chemistry present in these extreme environments.
FAF1 blocks ferroptosis by inhibiting peroxidation of polyunsaturated fatty acids
Authors: Cui Shaojie , Simmons Glenn , Vale Goncalo , Deng Yaqin , Kim Jungyeon , Kim Hyeonwoo , Zhang Ruihui , McDonald Jeffrey G. , Ye Jin
Published: April 2022

Significance

The current study reveals the functions of FAF1 in protecting cells from ferroptosis, a novel cell death pathway triggered by PUFA peroxidation. In the absence of FAF1, cultured cells and mice are extremely sensitive to ferroptosis when exposed to physiological levels of PUFAs. Mechanistically, FAF1 sequesters PUFAs into the hydrophobic core of a global structure that limits their access to positively charged Fe
2+
, which catalyzes the peroxidation reaction. These observations suggest that FAF1-mediated protection of PUFA peroxidation plays a critical role in preventing initiation of ferroptosis.
Alcohol use Disorder Pharmacotherapy and Treatment in Primary Care (ADaPT-PC) Trial: Impact on Identified Barriers to Implementation
Authors: Hagedorn Hildi J. , Wisdom Jennifer P. , Gerould Heather , Pinsker Erika , Brown Randall , Dawes Michael , Dieperink Eric , Myrick Donald Hugh , Oliva Elizabeth M. , Wagner Todd H. , Harris Alex H. S.
Published: April 2022

Background: A minority of individuals meeting diagnostic criteria for alcohol use disorders (AUD) receive any type of formal treatment. Developing options for AUD treatment within primary care settings is imperative to increase treatment access. A multi-faceted implementation intervention including provider and patient education, clinician reminders, development of local champions and ongoing facilitation was designed to enhance access to AUD pharmacotherapy in primary care settings at three large Veterans Health Administration (VHA) facilities. This qualitative study compared pre-implementation barriers to post-implementation barriers identified via provider interviews to identify those barriers addressed and not addressed by the intervention to better understand the limited impact of the intervention. Methods: Following the nine-month implementation period, primary care providers at the three participating facilities took part in qualitative interviews to collect perceptions regarding which pre-implementation barriers had and had not been successfully addressed by the intervention. Participants included 20 primary care providers from three large VHA facilities. Interviews were coded using common coding techniques for qualitative data using the Consolidated Framework for Implementation Research (CFIR) codebook. Summary reports were created for each CFIR construct for each facility and the impact of each CFIR construct on implementation was coded as positive, neutral, or negative. Results: Some barriers identified during pre-implementation interviews were no longer identified as barriers in the post-implementation interviews. These included Relative Advantage, Relative Priority, and Knowledge & Beliefs about the Innovation. However, Compatibility, Design Quality & Packaging, and Available Resources remained barriers at the end of the implementation period. No substantial new barriers were identified. Conclusions: The implementation intervention appears to have been successful at addressing barriers that could be mitigated with traditional educational approaches. However, the intervention did not adequately address structural and organizational barriers to implementation. Recommendations for enhancing future interventions are provided.
Altered brain functional connectivity in the frontoparietal network following an ice hockey season
Authors: DiFabio Melissa S. , Smith Daniel R. , Breedlove Katherine M. , Pohlig Ryan T. , Buckley Thomas A. , Johnson Curtis L.
Published: April 2022

Sustaining sports‐related head impacts has been reported to result in neurological changes that potentially lead to later‐life neurological disease. Advanced neuroimaging techniques have been used to detect subtle neurological effects resulting from head impacts, even after a single competitive season. The current study used resting‐state functional magnetic resonance imaging to assess changes in functional connectivity of the frontoparietal network, a brain network responsible for executive functioning, in collegiate club ice hockey players over one season. Each player was scanned before and after the season and wore accelerometers to measure head impacts at practices and home games throughout the season. We examined pre‐ to post‐season differences in connectivity within the frontoparietal and default mode networks, as well as the relationship between the total number of head impacts sustained and changes in connectivity. We found a significant interaction between network region of interest and time point (p = .016), in which connectivity between the left and right posterior parietal cortex seed regions increased over the season (p < .01). Number of impacts had a significant effect on frontoparietal network connectivity, such that more impacts were related to greater connectivity differences over the season (p = .042). Overall, functional connectivity increased in ice hockey athletes over a season between regions involved in executive functioning, and sensory integration, in particular. Furthermore, those who sustained more impacts had the greatest changes in connectivity. Consistent with prior findings in resting‐state sports‐related head impact literature, these findings have been suggested to represent brain injury.

Highlights

Functional connectivity of the frontoparietal network significantly increased between the pre‐ and post‐season, which may be a compensatory mechanism driven by neural tissue injury caused by repetitive head impacts.

Changes in frontoparietal network connectivity are related to head impact exposure, measured as the number of head impacts sustained in a single season.

Functional connectivity of the default mode network did not change over an ice hockey season.
Terahertz bremsstrahlung and frequency comb induced by variable motion of an antiferromagnetic domain wall
Authors: Ge Xu , Chen Yangyi , Cao Yue , Li Can , Li Tailin , Li Ziquan , You Long , Liang Shiheng , Yang Xiaofei , Zhang Yue
Published: April 2022

We numerically investigate the emission of spin wave (SW) packets from an antiferromagnetic (AFM) domain wall (DW) moving at a varying velocity. This SW is analogous to the bremsstrahlung of a charge with variable motion. The SW packets are emitted towards both sides of DW in the DW acceleration/deceleration process. The frequency of this bremsstrahlung-type SW is at sub-terahertz (THz), which is one magnitude lower than that of SW emitted by the Lorentz contraction of DW. Based on the bremsstrahlung-type SW, we proposed a frequency comb with a sub-THz central frequency and a GHz frequency interval by exploiting the back-and-forth DW variable motion. Our work paves a way for developing a spin–orbit-torque -based AFM THz device with a tunable frequency band.
Sub-nanometer-sized carbon nanoparticle shows higher biocompatibility to DNA than nanometer-sized nanoparticles
Authors: Lin Shujing , Wang Xiuxiu , Yang Yanmei , Meng Xuanyu , Qu Yuanyuan , Li Yong-Qiang , Zhao Mingwen , Liu Xiangdong , Li Weifeng
Published: April 2022

Nanomaterials have been extensively studied for their potential applications in biomedical research, but the concerns of nanotoxicity still remain. A systematic understanding of how the geometrical factors of nanomaterials, especially the dimensional size, regulating the toxicity is critical for the development of biomedical materials, which has yet to be documented. In this work, we have studied how the ultra-small-sized C28 nanoparticles bind to and regulate the structure of double stranded (dsDNA) by molecular dynamics simulations. Our results show that the C28 molecule can strongly bind to the nucleic acid terminal or the minor groove. It is interesting to observe a high sequence preference for C28 binding which prefers to bind to GC-rich than AT-rich segments. The C28 binding does not cause evident structural distortion and has little effect on the global motion of dsDNA, showing relatively higher biocompatibility than most reported nanomaterials that are usually at the nanometer size. These results reveal a fact that the nanomaterials toxicity is highly correlated to their size where sub-nanometer sized materials may have higher biocompatibility. This could provide deep understanding of how to control the biomaterials effects and might further extend applications of nanomaterials in biomedical research.
Uncertainty evaluation of thermodynamic properties estimated with online data tools: vapor pressure as case study
Authors: Lecuna Maricarmen , Sassi Guido
Published: April 2022

Online databanks are a convenient source of information whenever thermodynamic properties are required for calculations, in both scientific and engineering environment. The data listed in these repositories is usually reported along with a range of validity and their sources. The values of the thermodynamic properties can usually be retrieved from databases and handbooks, in the form of tables, curves or correlations with regression parameters. Most of the times, little to no information is given on the uncertainty of the reported estimates, let alone regression parameters uncertainty. Evaluating the sources of uncertainty in any model is fundamental to verify the significance of the results for a specific application. Knowing the uncertainty, makes the difference between trusted values and random values. Depending on the model where the property is required and its application (the use of results), the contribution to the total uncertainty of thermodynamic properties and constants can surpass the contributions of other experimental input quantities. In this work, the methods described in the ‘Guide for the expression of uncertainty in measurement’ are used to evaluate the uncertainty of a thermodynamic property of a pure substance, calculated based on the constants and references reported in two important online data banks (NIST and Dortmund Databank). The vapor pressure is considered as case study and several definitions with their relevant sources of uncertainty are presented. The aim of the work is to highlight the limitations of properties data commonly used in engineering estimations, as well as the importance of accounting for their uncertainty. Following established metrological guidelines, a full procedure has been developed, with specific considerations aimed to account for the ‘quality’ of the realization of the definition of the measurand as a source of uncertainty of the property.
Primary measurement method for the characterisation of impedance standard in the mΩ range
Authors: Rusanto Benyamin H , Seitz Steffen , Funck Torsten , Heinrich Marco
Published: April 2022

Impedance standards having impedance values in the low mΩ range, with non-zero reactances, and operable with alternating current-currents of a few Amps and up to a few kHz are needed for appropriate impedance meter calibration. These challenging operation parameters are most relevant for electrochemical impedance spectroscopy of high energy Li-ion battery cells. We present a primary measurement method that can be used for the characterisation of respective impedance standards traceable to the SI. Basically, two calibrated high precision DC voltage meters are used to sample the voltages across a characterised reference resistor and the impedance standard under test, while both are excited with the same ac current. The measured voltages are fitted with sin waves and the complex impedance value is calculated from the amplitudes and phase difference of the voltage curves. We present the measurement results of a test impedance in mΩ range, including a full uncertainty budget. Moduli of the measured impedances are compared with those of another method that has been presented recently. The results are equivalent up to 1 kHz and within a relative expanded uncertainty of around 0.47%.
Convergence analysis of a viscosity parameter recovery algorithm for the 2D Navier–Stokes equations
Authors: Martinez Vincent R
Published: April 2022

In this paper, the convergence of an algorithm for recovering the unknown kinematic viscosity of a two-dimensional incompressible, viscous fluid is studied. The algorithm of interest is a recursive feedback control-based algorithm that leverages observations that are received continuously-in-time, then dynamically provides updated values of the viscosity at judicious moments. It is shown that in an idealized setup, convergence to the true value of the viscosity can indeed be achieved under a natural and practically verifiable non-degeneracy condition. This appears to be first such result of its kind for parameter estimation of nonlinear partial differential equations. Analysis for two parameter update rules is provided: one which involves instantaneous evaluation in time and the other, averaging in time. The proof of convergence for either rule exploits sensitivity-type bounds in higher-order Sobolev topologies, while the instantaneous version particularly requires delicate energy estimates involving the time-derivative of the sensitivity-type variable. Indeed, a crucial component in the analysis is the identification of a dissipative structure for the time-derivative of the sensitivity-type variable, which ultimately ensures a favorable dependence on the tuning parameter of the algorithm.