bluuebunny/crossref_metadata_2025 huggingface dataset:
Schwangerschaft nach sequenzieller Leber-Nieren-Transplantation bei Hyperoxalurie Typ I: Was ist daran anders als sonst?
Authors: Schwarz Anke , Günter Hans Heinrich , Haller Hermann
Published: November 2020

Schwangerschaft nach Nierentransplantation ist immer ein Risiko sowohl für Mutter und Kind als auch für das Nierentransplantat. Wir beschreiben den Fall einer jungen Frau mit primärer Hyperoxalurie Typ 1 und dadurch bedingtem terminalem Nierenversagen durch Nephrokalzinose. Sie hatte als 10-jähriges Kind eine Lebertransplantation durch Fremdspende erhalten zur Behebung des Enzymdefektes in der Leber sowie 2 Monate später eine Nierentransplantation durch Nierenspende der Mutter. Die Immunsuppression erfolgte durch Cyclosporin, Mycophenolatmofetil und Prednisolon. Das Lebertransplantat hatte 3 Abstoßungen, jeweils behandelt mit Steroidboli. Das Nierentransplantat zeigte eine langsame Funktionsverschlechterung über die Jahre, Entwicklung einer Proteinurie von 1 Gramm Protein pro 1 Gramm Kreatinin sowie eine mittelschwere Hypertonie. Trotzdem hatte die Frau einen persistierenden dringenden Kinderwunsch und setzte sich damit durch. Der Artikel beschreibt die speziellen Probleme dieses Falles: (1) das allgemeine Problem, Patienten mit Hyperoxalurie Typ 1 überhaupt zu transplantieren; (2) das spezielle Problem der Schwangerschaft dieser 31-jährigen Frau mit genetisch bedingter Nierenerkrankung und vorangehender Transplantation von 2 soliden Organen vor 18 Jahren; (3) die mit einem immunologisch instabilen Lebertransplantat und einem Nierentransplantat einhergehende langsam progrediente Funktionsverschlechterung und ansteigende Proteinurie. Die generellen Richtlinien für eine Schwangerschaft nach Nierentransplantation werden aufgezeigt im Vergleich zu dem hier beschriebenen Fall einer Schwangerschaft, bei der fast alle Parameter außerhalb der Richtlinien liegen bei persistierend starkem Kinderwunsch dieser Frau.
Gibt es eine neue Kopfspeicheldrüse? – Eher nicht!
Authors: Guntinas-Lichius Orlando , Ihrler Stephan , Freesmeyer Martin , Gühne Falk , Kluge Regine , Bräuer Lars , Iro Heinrich , Paulsen Friedrich , Dietz Andreas , Bechmann Ingo
Published: November 2020

Im Oktober 2020 vermeldeten die Laienpresse, aber auch einige medizinische Journale und Internetseiten, die angebliche Entdeckung einer neuen Speicheldrüse im Nasenrachen ausgehend von Positronen-Emissions-Tomografie-Computertomografie-Untersuchungen mit Liganden für das Prostata-spezifische Membranantigen (PSMA-PET/CT). Als interdisziplinäre Gruppe aus den Fachbereichen Anatomie, Pathologie, Nuklearmedizin und HNO-Heilkunde kommen wir zu der Ansicht, dass hier eine Anhäufung von kleinen Speicheldrüsen beschrieben wird. Kleine Speicheldrüsen im Nasenrachen und peritubar sind mindestens seit 1866 bekannt und immer wieder in der Literatur und in Lehrbüchern beschrieben. Das PSMA-PET/CT könnte aber geeignet sein, bei einer Bestrahlungsplanung funktionell relevante Anhäufungen von Schleimhautspeicheldrüsen, wie beispielsweise im Bereich des Nasenrachens, besser darzustellen und zu schonen. Dies sollte in klinischen Studien geprüft werden.
Management of patients after failed peroral endoscopic myotomy: a multicenter study
Authors: Ichkhanian Yervant , Assis Daniella , Familiari Pietro , Ujiki Michael , Su Baily , Khan Sarah R. , Pioche Mathieu , Draganov Peter V. , Cho Joo young , Eleftheriadis Nikolas , Barret Maximilien , Haji Amyn , Velanovich Vic , Tantau Marcel , Marks Jeffrey M. , Bapaye Amol , Sedarat Alireza , Albeniz Eduardo , Bechara Robert , Kumta Nikhil A. , Costamagna Guido , Perbtani Yaseen B. , Patel Mehul , Sippey Megan , Korrapati Sravan K. , Jain Rishabh , Estremera Fermín , El Zein Mohamad H. , Brewer Gutierrez Olaya I. , Khashab Mouen A.
Published: November 2020

Background Although peroral endoscopic myotomy (POEM) is highly effective for the management of achalasia, clinical failures may occur. The optimal management of patients who fail POEM is not well known. This study aimed to compare the outcomes of different management strategies in patients who had failed POEM.

Methods This was an international multicenter retrospective study at 16 tertiary centers between January 2012 and November 2019. All patients who underwent POEM and experienced persistent or recurrent symptoms (Eckardt score > 3) were included. The primary outcome was to compare the rates of clinical success (Eckardt score ≤ 3) between different management strategies.

Results 99 patients (50 men [50.5 %]; mean age 51.4 [standard deviation (SD) 16.2]) experienced clinical failure during the study period, with a mean (SD) Eckardt score of 5.4 (0.3). A total of 29 patients (32.2 %) were managed conservatively and 70 (71 %) underwent retreatment (repeat POEM 33 [33 %], pneumatic dilation 30 [30 %], and laparoscopic Heller myotomy (LHM) 7 [7.1 %]). During a median follow-up of 10 (interquartile range 3 – 20) months, clinical success was highest in patients who underwent repeat POEM (25 /33 [76 %]; mean [SD] Eckardt score 2.1 [2.1]), followed by pneumatic dilation (18/30 [60 %]; Eckardt score 2.8 [2.3]), and LHM (2/7 [29 %]; Eckardt score 4 [1.8]; P = 0.12). A total of 11 patients in the conservative group (37.9 %; mean Eckardt score 4 [1.8]) achieved clinical success.

Conclusion This study comprehensively assessed an international cohort of patients who underwent management of failed POEM. Repeat POEM and pneumatic dilation achieved acceptable clinical success, with excellent safety profiles.
2-Carbamimidoylbenzoic Acid as a New Effective and Available Precursor for the Synthesis of Substituted 2-(Pyrimidin-2-yl)benzoic Acids
Authors: Hordiyenko Olga V. , Tkachuk Volodymyr A. , Shishkanu Vyacheslav O. , Tkachuk Tetiana M. , Shishkina Svitlana V.
Published: November 2020

A new approach to the synthesis of 2-(pyrimidin-2-yl)benzoic acids based on the ring contraction of the 2-carbamimidoylbenzoic acid [(2-amidinobenzoic) acid] with 1,3-dicarbonyl compounds and their synthetic equivalents has been developed. The intramolecular condensation of the obtained acids with 1,3-dielectrophiles proceeds with the formation of the 4,6-dihydropyrimido[2,1-a]isoindole-4,6-dione system, the pyrrolidone ring of which is easily opened under the action of weak nucleophiles. The reaction of 2-amidinobenzoic acid with chromones, which have an aryloxy group at 3-position does not stop at the step of pyrimidine ring formation and undergoes further spontaneous cyclization into 2-(benzo[4,5]furo[3,2-d]pyrimidin-2-yl)benzoic acids.
Synthesis of Tryptamines through a Novel Brønsted Acid Mediated Tandem Reaction Initiated by α-Iminol Rearrangement of Transient 2-Substituted 2-Hydroxycyclobutylimines
Authors: Frongia Angelo , Serusi Lorenzo , Cuccu Federico , Secci Francesco , Aitken David J.
Published: November 2020

A novel Brønsted acid promoted condensation reaction between a primary aniline and 2-hydroxycyclobutanone provides access to diverse tryptamine derivatives in moderate to good yields. The proposed mechanism involves an α-iminol rearrangement, ring expansion, ring closure, and a depart-and-return rearrangement process.
Imaging Diagnosis of Adenomyosis
Authors: O'Shea Aileen , Figueiredo Gabrielle , Lee Susanna I.
Published: November 2020

Uterine adenomyosis can be diagnosed on ultrasonography (US) and magnetic resonance imaging (MRI) with a high degree of accuracy. Adenomyosis is a myometrial process that can appear as diffuse or focal on imaging. Diffuse adenomyosis typically causes uterine enlargement, while focal adenomyosis can mimic other myometrial lesions, such as leiomyomas. Imaging features frequently seen on US include a heterogenous thickened myometrium and myometrial cysts. On MRI, widening of the junctional zone, whether focal or diffuse, and the presence of myometrial cysts, either simple or hemorrhagic, support the diagnosis of adenomyosis. Despite these characteristic imaging appearances, there are several gynecologic pathologies which can mimic adenomyosis and it is important to be vigilant of these when interpreting cross-sectional imaging exams. The decision to evaluate patients with US or MRI is contingent on multiple factors, including availability of the necessary technology and expertise for the latter. However, MRI appears to offer greater specificity and positive predictive value for the diagnosis of adenomyosis.
European Pediatric Surgeon' Association Survey on the Management of Short-Bowel Syndrome
Authors: Dariel Anne , Faure Alice , Martinez Leopoldo , Morini Francesco , Pini Prato Alessio , Friedmacher Florian , Coste Marie-Edith
Published: November 2020

Introduction The aim of this study was to assess the management of short-bowel syndrome (SBS) at the time of primary surgery, and the strategies used to facilitate enteral autonomy depending on the institutional expertise.

Materials and Methods An online questionnaire was sent in 2019 to members of The European Pediatric Surgeons' Association.

Results Among the 65 responding members (26 countries, 85% from university hospitals), 57% manage less than three new patients with SBS per year (group A), and 43% at least three patients (group B). The cut-off of three patients treated yearly used in our study was defined after statistical analysis of different cut-offs. A multidisciplinary intestinal rehabilitation program is significantly more frequent in group B than in group A (85 and 53%, respectively; p = 0.009). Considering the primary surgical management of multiple intestinal atresia and congenital ultra-short bowel with jejunal atresia, primary surgical strategies to optimize bowel length are more often used in group B than group A (p = 0.09 and p = 0.04, respectively). A minimum of one intestinal lengthening procedure every 2 to 3 years is significantly more frequent in group B than group A (95 and 45%, respectively; p = 0.0013). Among the strategies used to promote intestinal adaptation, group B (35%) uses significantly more often glucagon-like peptide 2 analogs than group A (10%) (p = 0.02).

Conclusion Based on our survey, a minimum number of SBS patients treated yearly is required to manage this challenging disease according to up-to-date medical and surgical strategies. However, whatever their level of expertise is in managing SBS, most of pediatric surgeons are involved in the primary surgery. Medical education programs about SBS should be more largely available to pediatric surgeons.
Classical limits of unbounded quantities by strict quantization
Authors: Browning Thomas L. , Feintzeig Benjamin H. , Gates-Redburg Robin , Librande Jonah , Soiffer Rory
Published: November 2020

This paper extends the tools of C*-algebraic strict quantization toward analyzing the classical limits of unbounded quantities in quantum theories. We introduce the approach first in the simple case of finite systems. Then, we apply this approach to analyze the classical limits of unbounded quantities in bosonic quantum field theories, with particular attention to number operators and Hamiltonians. The methods take classical limits in a representation-independent manner and so allow one to compare quantities appearing in inequivalent Fock space representations.
A fast local embedded boundary method suitable for high power electromagnetic sources
Authors: Thavappiragasam Mathialakan , Christlieb Andrew , Luginsland John , Guthrey Pierson
Published: November 2020

High power sources of electromagnetic energy often require complicated structures to support electromagnetic modes and shape electromagnetic fields to maximize the coupling of the field energy to intense relativistic electron beams. Geometric fidelity is critical to the accurate simulation of these High Power Electromagnetic (HPEM) sources. Here, we present a fast and geometrically flexible approach to calculate the solution to Maxwell’s equations in vector potential form under the Lorenz gauge. The scheme is an implicit, linear-time, high-order, A-stable method that is based on the method of lines transpose (MOLT). As presented, the method is fourth order in time and second order in space, but the A-stable formulation could be extended to both high order in time and space. An O(n) fast convolution is employed for space-integration. The main focus of this work is to develop an approach to impose perfectly electrically conducting (PEC) boundary conditions in MOLT by extending our past work on embedded boundary methods. As the method is A-stable, it does not suffer from small time step limitations that are found in explicit finite difference time domain methods when using either embedded boundary or cut-cell methods to capture geometry. This is a major advance for the simulation of HPEM devices. While there is no conceptual limitation to develop this in 3D, our initial work has centered on 2D. The extension to 3D requires validation that the proposed fixed point iteration will converge and is the subject of our follow-up work. The eventual goal is to combine this method with particle methods for the simulations of plasma. In the current work, the scheme is evaluated for EM wave propagation within an object that is bounded by PEC. The consistency and performance of the scheme are confirmed using the ping test and frequency mode analysis for rotated square cavities—a standard test in the HPEM community. We then demonstrate the diffraction Q value test and the use of this method for simulating an A6 magnetron. The ability to handle both PEC and open boundaries in a standard device test problem, such as the A6, gives confidence on the robustness of this new method.
Smart local orbitals for efficient calculations within density functional theory and beyond
Authors: Gandus G. , Valli A. , Passerone D. , Stadler R.
Published: November 2020

Localized basis sets in the projector augmented wave formalism allow for computationally efficient calculations within density functional theory (DFT). However, achieving high numerical accuracy requires an extensive basis set, which also poses a fundamental problem for the interpretation of the results. We present a way to obtain a reduced basis set of atomic orbitals through the subdiagonalization of each atomic block of the Hamiltonian. The resulting local orbitals (LOs) inherit the information of the local crystal field. In the LO basis, it becomes apparent that the Hamiltonian is nearly block-diagonal, and we demonstrate that it is possible to keep only a subset of relevant LOs that provide an accurate description of the physics around the Fermi level. This reduces to some extent the redundancy of the original basis set, and at the same time, it allows one to perform post-processing of DFT calculations, ranging from the interpretation of electron transport to extracting effective tight-binding Hamiltonians, very efficiently and without sacrificing the accuracy of the results.
Accelerated design of photovoltaic Ruddlesden–Popper perovskite Ca6Sn4S14−xOx using machine learning
Authors: Hu Junjie , Wang Chenxi , Li Qianhong , Sa Rongjian , Gao Peng
Published: November 2020

Ruddlesden–Popper (R–P) phase layered chalcogenide perovskites had attracted broad interest as potential lead-free high-performance photovoltaic absorbers. Ca3Sn2S7 is a graphene-like RP phase perovskite with a ultrahigh carrier mobility and a more significant absorption coefficient in the visible light region than those of the classic hybrid halide perovskite MAPbI3. However, the ultra-low direct bandgap of Ca3Sn2S7 is unfavorable for the photovoltaic application. In this work, we addressed these issues by designing an anion-mixed RP phase perovskite with an appropriate direct bandgap. The idea was to adjust its bandgap with different O proportions from 7.14% to 35.71%. We considered more than 3000 derivative structures of Ca6Sn4S14−xOx (x = 1–5) that were related to the arrangement of mixed S/O atoms. To ensure that the computational models were based on the screened optimal structures, we found that Ca6Sn4S14−xOx (x = 4 and 5) could increase the bandgap of Ca3Sn2S7 into the range of 1.19 eV–1.64 eV and 1.02 eV–1.47 eV, respectively. Meanwhile, Ca6Sn4S14−xOx also had absorption coefficients beyond 105 cm−1. These results made them possible candidates as new-generation photovoltaic absorbers. We also trained the supervised graph convolutional network and the unsupervised Mat-generative adversarial networks (GAN) for accelerating the density functional theory (DFT) calculation of over 3000 structures. Even if considering the time to generate the training samples by DFT, we prove that the Mat-GAN strategy could reduce the DFT calculation consumption by more than 99%. In order to reveal the distributive characteristics of the arrangement of mixed S/O, we adopted active machine learning to analyze the differences of these structures. We found that the O atom would preferentially replace the S in the Sn–S–Sn position.
Quantum magic squares: Dilations and their limitations
Authors: De las Cuevas Gemma , Drescher Tom , Netzer Tim
Published: November 2020

Quantum permutation matrices and quantum magic squares are generalizations of permutation matrices and magic squares, where the entries are no longer numbers but elements from arbitrary (non-commutative) algebras. The famous Birkhoff–von Neumann theorem characterizes magic squares as convex combinations of permutation matrices. In the non-commutative case, the corresponding question is as follows: Does every quantum magic square belong to the matrix convex hull of quantum permutation matrices? That is, does every quantum magic square dilate to a quantum permutation matrix? Here, we show that this is false even in the simplest non-commutative case. We also classify the quantum magic squares that dilate to a quantum permutation matrix with commuting entries and prove a quantitative lower bound on the diameter of this set. Finally, we conclude that not all Arveson extreme points of the free spectrahedron of quantum magic squares are quantum permutation matrices.
Spectroscopic imaging of surfaces—Sum frequency generation microscopy (SFGM) combined with compressive sensing (CS) technique
Authors: Li Hao , Kelly Kevin F. , Baldelli Steven
Published: November 2020

Surface chemistry is notoriously difficult to study, in part, due to the decreased number of molecules that contribute to the properties compared to the bulk phase but often has significant effects on the chemical activity of the material. This is especially true in topics such as corrosion, catalysis, wetting, and many others in nature and industry. Sum frequency generation (SFG) spectroscopy was developed for interface studies due to its high molecular selectivity and surface sensitivity, which is quite useful to study the effects of structural inhomogeneity in microscopy. Compressive sensing (CS) combined with SFG spectroscopy minimizes the imaging time while still producing quality images. Selected systems are presented here to demonstrate the capability of CS-SFG microscopy. CS-SFG microscopy successfully distinguished the static monolayer molecular mixtures, the orientations and adsorption of adsorbed molecules by the dip-coating technique, and the localized CO behaviors on polycrystalline Pt electrodes. Further discussion includes dynamic imaging as a future direction in CS-SFG microscopy. As materials and surfaces become more complex, imaging with chemical contrast becomes indispensable to understanding their performance and CS-SFG microscopy seems highly beneficial in this respect.
A hybrid self-aligned MIS-MESFET architecture for improved diamond-based transistors
Authors: Lee Young Tack , Vardi Alon , Tordjman Moshe
Published: November 2020

Diamond is a promising electronic semiconductor candidate that has recently attracted intense interest in the implementation of its superior physical properties in electronic devices. In particular, attention has been focused on the surface transfer doping of diamond, in which the hydrogen-terminated diamond (diamond:H) benefices of a unique conductive two-dimensional hole gas (2DHG) layer at the diamond's sub-surface upon coverage with a suitable surface acceptor. Several diamond:H transistors have been developed. However, their inherent architecture dependence on the diamond:H conductive surface sensitivity to harsh processing environments has been a major barrier to the realization of high-performance devices. Here, we report on a diamond:H transistor structure that incorporates a mutual diamond:H active channel into the hybrid model of a metal-semiconductor field-effect transistor (MESFET) and a self-aligned metal-insulator-semiconductor FET (MISFET) with a common gate connection. The resulting diamond:H hybrid transistor exhibits a beneficial symbiosis that includes the advantages of both the MISFET (a high ON current of 0.8 μA/μm and a low OFF current of ∼10−9 μA/μm) and MESFET (almost an ideal subthreshold swing of 67 mV/dec) performance operations in the same multilayered device.
Efficient modeling of three-dimensional convection–diffusion problems in stationary flows
Authors: Thiele Jan Christoph , Gregor Ingo , Karedla Narain , Enderlein Jörg
Published: November 2020

A large number of transport processes in physics, chemistry, and engineering are described by a convection–diffusion equation. This equation is notoriously difficult to solve due to the presence of convection-related first-order gradient differential operators. We describe a new and efficient numerical method for solving the convection–diffusion equation for laminar flows within channels of arbitrary cross section. It is based on reducing the convection–diffusion equation to a set of pure diffusion equations with a complex-valued potential for which fast and numerically stable solvers are readily available. Additionally, we use an eigenvector projection method that allows us to compute snapshots of full concentration distributions over millions of finite elements within a few seconds using a conventional state-of-the-art desktop computer. Our results will be important for all applications where diffusion and convection are both important for correctly describing material transport.
Photothermal spectroscopy: A promising tool for nanofluids
Authors: Usoltseva Liliya O. , Korobov Mikhail V. , Proskurnin Mikhail A.
Published: November 2020

In recent years, the demand for more efficient cooling circuits has resulted in active studies of nanofluids, two-component liquids consisting of a base fluid, and dispersed nanoparticles with high thermal conductivity. From the viewpoint of both physics and chemistry, nanofluids are systems that require the characterization of many interconnected thermal and chemical properties. This perspective article sums up the state of the art and recent trends in the development and applications of nanofluids and especially carbon nanofluids. A focus of the paper is the possibilities of photothermal and photoacoustic methods—as techniques combining molecular spectroscopy and thermal characterization—for the assessment of thermal conductivity and thermal diffusivity of nanofluids. The possibilities of photothermal spectroscopy for wider characterization of nanofluids and related materials are discussed and compared with other techniques. As nanofluids are one of the examples of complex objects dedicated to photothermal spectroscopy, more general outlooks of phototermics are also discussed.
Topological semimetals from the perspective of first-principles calculations
Authors: Li Jiaheng , Zhang Zetao , Wang Chong , Huang Huaqing , Gu Bing-Lin , Duan Wenhui
Published: November 2020

Topological semimetals (TSMs) refer to electronic gapless phases that exhibit topological band crossings around the Fermi level and have intrigued enormous research interest in the past few decades. There have been many theoretical and experimental progresses regarding TSMs, and first-principles calculations have been proven to be an instrumental tool in finding candidate materials for TSMs. In this tutorial, we will focus on two representative types of TSMs—Weyl and Dirac semimetals and summarize the recent progress from the perspective of first-principles calculations. First of all, the basic concepts of TSMs, the generic topological invariants, and the frequently used techniques within first-principles calculations are briefly introduced. Second, taking typical materials as representative examples, we summarize the characteristic electronic properties, formation mechanisms, and general methodologies for Weyl and Dirac semimetals, respectively. In the last part, we present a short review of recent progresses on other types of TSMs.
Single-file diffusion in a bi-stable potential: Signatures of memory in the barrier-crossing of a tagged-particle
Authors: Lapolla Alessio , Godec Aljaž
Published: November 2020

We investigate memory effects in barrier-crossing in the overdamped setting. We focus on the scenario where the hidden degrees of freedom relax on exactly the same time scale as the observable. As a prototypical model, we analyze tagged-particle diffusion in a single file confined to a bi-stable potential. We identify the signatures of memory and explain their origin. The emerging memory is a result of the projection of collective many-body eigenmodes onto the motion of a tagged-particle. We are interested in the “confining” (all background particles in front of the tagged-particle) and “pushing” (all background particles behind the tagged-particle) scenarios for which we find non-trivial and qualitatively different relaxation behaviors. Notably and somewhat unexpectedly, at a fixed particle number, we find that the higher the barrier, the stronger the memory effects are. The fact that the external potential alters the memory is important more generally and should be taken into account in applications of generalized Langevin equations. Our results can readily be tested experimentally and may be relevant for understanding transport in biological ion-channels.
Conceptual design of a collimator for the neutron emission profile monitor in JT-60SA using Monte Carlo simulations
Authors: Sumida S. , Shinohara K. , Nishitani T. , Ogawa K. , Bando T. , M. Sukegawa A. , Ishikawa M. , Takada E. , Bierwage A. , Oyama N.
Published: November 2020

Materials and structures of a collimator for a new neutron emission profile monitor in JT-60SA are examined through Monte Carlo simulations using the Monte Carlo N-Particle transport code. First, the shielding properties of various material combinations are compared in order to determine a combination with high shielding performances against both neutrons and gamma-rays. It is found that a collimator consisting of borated polyethylene and lead has a high shielding performance against neutrons. Moreover, a high shielding performance against gamma-rays is obtained when a lead pipe with a radial thickness of 0.01 m is inserted into a collimation tube. Second, we demonstrate that it is possible to improve the spatial resolution to a desired level by installing a thin tubular extension structure that fits into the limited space available between the main collimator block and the tokamak device. Finally, the collimator structures that meet both the targeted spatial resolutions (<10% of the plasma minor radius) and the targeted counting rate (105 cps order) are discussed.
Defect spectroscopy and non-ionizing energy loss analysis of proton and electron irradiated p-type GaAs solar cells
Authors: Pellegrino C. , Gagliardi A. , Zimmermann C. G.
Published: November 2020

Admittance spectroscopy combined with non-ionizing energy loss (NIEL) analysis is shown to be a powerful tool for analyzing solar cell radiation degradation, not relying on the change of macroscopic cell parameters. GaAs component cells, representative of the middle sub-cell in Ga0.5In0.5P/GaAs/Ge solar cells, were irradiated with protons and electrons in the 0.5–3 MeV energy range. Four irradiation-induced defects are identified in the p-type base layer. The nature of each defect is assessed by analyzing the dependence of its introduction rate on the NIEL deposited by electrons in the semiconductor. The expected linear relationship is only achieved if a unique threshold energy Ed is ascribed to each defect, which ranges from 9 to 38 eV. An electron NIEL with Ed=21eV, customarily used for GaAs-based solar cell degradation analysis, is an approximation of the relative abundance of these four defects. The 21 eV value is thus a GaAs material-specific parameter, independent of the electrical device design. In addition, the type and energy of the incident particle is correlated with the relative abundance of high Ed defects. The impact of each defect on the macroscopic electrical parameters of the cell, namely, the open-circuit voltage VOC, the short-circuit current density JSC, and the recombination current density J02, is assessed with the help of a Pearson analysis. The different effectiveness of electron and proton irradiation on parameters dominated by recombination in the depleted region, such as VOC or J02, is attributed in part to the influence of the particle recoil spectra on the defect capture cross section.
Magnetic field based actuation and amalgamation of ferrofluid droplets on hydrophobic surface: An experimental and numerical study
Authors: Khan Adnan , Li Qian-Ping , Niu Xiao-Dong , Wang Yu-Qiao , Wen Ming-Fu , Li De-Cai , Yamaguchi Hiroshi , Li Juan
Published: November 2020

This article presents a detailed experimental analysis along with numerical simulations to provide the information about shape evolutions and mechanism of actuation and amalgamation of the ferrofluid droplets deposited on a hydrophobic surface by moving a permanent magnet. To validate the numerical methods used in this article, a benchmark phenomenon of a sessile droplet spreading under the effect of a non-uniform magnetic field is first simulated, and the results are compared with available experimental observations. To further ensure the accuracy of experimental and numerical techniques and to understand the wetting properties and spreading behavior of non-stationary ferrofluid droplets, a prototype demonstration of the merging droplets on a hydrophobic solid surface in the presence of a permanent magnet is designed. It is observed that for hydrophobic surfaces, the merging droplets entrap an air bubble at the time of first contact. Moreover, the physics behind the transient variations of droplet morphology and the effect of the state-of-the-art parameters on droplet actuation are also discussed. The force evaluation, energy variations, velocity contours, and velocity vectors of the moving droplet are provided to understand the internal behavior of droplet mobility. Experiments are performed several times with different speeds of moving a magnet to find the critical velocity when the droplet fails to follow the magnet motion. While doing so, we encounter an anomalous phenomenon of thread formation and daughter droplet generation at the receding end of the sliding droplet. A phase diagram is also provided in the end, which describes different regions of the sliding phenomenon.
Similarity law and frequency scaling in low-pressure capacitive radio frequency plasmas
Authors: Fu Yangyang , Zheng Bocong , Wen De-Qi , Zhang Peng , Fan Qi Hua , Verboncoeur John P.
Published: November 2020

We verify the similarity law (SL) and show a violation of frequency scaling (f-scaling) in low-pressure capacitive radio frequency (rf) plasmas via fully kinetic particle-in-cell simulations. The SL scaling relations for electron density and electron power absorption are first confirmed in similar rf discharges. Based on these results, with only the driving frequency varied, the f-scaling for electron density is also validated, showing almost the same trend as the SL scaling, across most of the frequency regime. However, violations of the f-scaling are observed at lower frequencies, which are found to be relevant to the electron heating mode transition from stochastic to Ohmic heating. Electron kinetic invariance is illustrated for the SL and f-scaling being valid, respectively, whereas the electron kinetic variation is observed when the f-scaling is violated.
Method of full polarization control of microwave fields in a scalable transparent structure for spin manipulation
Authors: Staacke Robert , John Roger , Kneiß Max , Osterkamp Christian , Diziain Séverine , Jelezko Fedor , Grundmann Marius , Meijer Jan
Published: November 2020

The application of transparent conducting oxides in electronic devices like solar cells or displays is common. By transferring this technology to quantum sensing and computing in the form of microwave conductors, it is possible to benefit from the advantages of these materials. By using indium tin oxide (ITO), it is demonstrated that at an arbitrary position below the conductor, an arbitrary elliptical microwave polarization can be produced by two independent sources. This is independent of the geometry and size of the ITO, whereby a non-resonant microwave approach can be chosen. Using single nitrogen vacancy (NV) centers in diamond in combination with a cross-like ITO structure, each NV center can be addressed with an ideal (clockwise or anticlockwise) microwave polarization. By optimizing the coupling of the microwave field to the NV centers and minimizing the conductor size, the creation of smaller devices compared to common approaches is possible.
Temperature effects on singlet fission dynamics mediated by a conical intersection
Authors: Sun Kewei , Xu Quan , Chen Lipeng , Gelin Maxim F. , Zhao Yang
Published: November 2020

Finite-temperature dynamics of singlet fission in crystalline rubrene is investigated by utilizing the Dirac–Frenkel time-dependent variational method in combination with multiple Davydov D2 trial states. To probe temperature effects on the singlet fission process mediated by a conical intersection, the variational method is extended to include number state propagation with thermally averaged Boltzmann distribution as initialization. This allows us to simulate two-dimensional electronic spectroscopic signals of two-mode and three-mode models of crystalline rubrene in the temperature range from 0 K to 300 K. It is demonstrated that an elevated temperature facilitates excitonic population transfer and accelerates the singlet fission process. In addition, increasing temperature leads to dramatic changes in two-dimensional spectra, thanks to temperature-dependent electronic dephasing and to an increased number of system eigenstates amenable to spectroscopic probing.
A novel and reliable interlayer exchange coupled nanomagnetic universal logic gate design
Authors: Mattela Venkat , Debroy Sanghamitra , Sivasubramani Santhosh , Acharyya Amit
Published: November 2020

In this paper, we propose an interlayer exchange coupling (IEC) based 3D universal NAND/NOR gate design methodology for the reliable and robust implementation of nanomagnetic logic design as compared to the state-of-the art architectures. Owing to stronger coupling scheme as compared to the conventional dipole coupling, the random flip of the states of the nanomagnets (i.e. the soft error) is reduced resulting in greater scalability and better data retention at the deep sub-micron level. Results obtained from Object Oriented Micromagnetic Framework micromagnetic simulation show even at a Curie temperature of the nanomagnets coupled through IEC, the logic function works properly as opposed to dipole coupled nanomagnets which fails at 5 K when scaled down to sub 50 nm. Contemplating the fabrication challenges, the robustness of the IEC design was studied for structural defects, positional misalignment, shape, and size variations. This proposed 3D universal gate design methodology benefits from the miniaturization of nanomagnets as well as reduces the effect of thermally induced errors resulting in opening up a new perspective for nanomagnet based design in magneto-logic devices.
Real-time dose control for electron-beam lithography
Authors: Yang-Keathley Yugu , Maloney Stephen A , Hastings J Todd
Published: November 2020

Shot-to-shot, or pixel-to-pixel, dose variation during electron-beam lithography is a significant practical and fundamental problem. Dose variations associated with charging, electron source instability, optical system drift, and ultimately shot noise in the e-beam itself conspire to critical dimension variability, line width/edge roughness, and limited throughput. It would be an important improvement to e-beam based patterning technology if real-time feedback control of electron-dose were provided so that pattern quality and throughput would be improved beyond the shot noise limit. In this paper, we demonstrate control of e-beam dose based on the measurement of electron arrival at the sample where patterns are written, rather than from the source or another point in the electron optical column. Our results serve as the first steps towards real-time dose control and eventually overcoming the shot noise.
Single-walled carbon nanotube membranes as non-reflective substrates for nanophotonic applications
Authors: Zhigunov Denis M , Shilkin Daniil A , Kokareva Natalia G , Bessonov Vladimir O , Dyakov Sergey A , Chermoshentsev Dmitry A , Mkrtchyan Aram A , Gladush Yury G , Fedyanin Andrey A , Nasibulin Albert G
Published: November 2020

We demonstrate that single-walled carbon nanotube (SWCNT) membranes can be successfully utilized as nanometer-thick substrates for enhanced visualization and facilitated study of individual nanoparticles. As model objects, we transfer optically resonant 200 nm silicon nanoparticles onto pristine and ethanol-densified SWCNT membranes by the femtosecond laser printing method. We image nanoparticles by scanning electron and bright-field optical microscopy, and characterize by linear and Raman scattering spectroscopy. The use of a pristine SWCNT membrane allows to achieve an order-of-magnitude enhancement of the optical contrast of the nanoparticle bright field image over the results shown in the case of the glass substrate use. The observed optical contrast enhancement is in agreement with the spectrophotometric measurements showing an extremely low specular reflectance of the pristine membrane (≤0.1%). Owing to the high transparency, negligibly small reflectance and thickness, SWCNT membranes offer a variety of perspective applications in nanophotonics, bioimaging and synchrotron radiation studies.
Finite element analysis of straight twisted polymer actuators using precursor properties
Authors: Higueras-Ruiz Diego R , Center Charles J , Feigenbaum Heidi P , Swartz Amy M , Shafer Michael W
Published: November 2020

Twisted polymer actuators (TPAs) are a promising new low-cost actuation technology that can generate torsional or linear actuation. While analytical models for TPAs have been explored to predict their thermal actuation responses, these models are either based on elastic properties of the twisted monofilament, which does not allow for design of initial twist, or ignore the internal stresses between layers. How the elastic properties of the precursor (untwisted) monofilament affects internal stresses is not well understood. Our goal is to better understand how the actuation response is affected by internal stresses. To study the internal stresses in TPAs, we simulate a straight twisted polymer actuator (STPA) using a finite element (FE) model. The linear elastic mechanical properties of the untwisted monofilament as a function of temperature are needed as inputs to the FE model, and are obtained experimentally. FE results are compared with experimental actuation responses and closed-form predictions using models which neglect internal stresses, namely the Shafer et al and the averaged Shafer et al models. The simulations and experiments use a STPA to generate torsional actuation under free torsion conditions. Under these conditions, we show that interlayer stresses are not the main driver for the torsional actuation of STPAs and FE model predicts experimental data about as well as closed-form models. Additionally, we use the internal stresses to better understand the actuation mechanism of TPAs and evaluate their effects on STPAs torsional actuation under free torsion conditions.
Untethered, high-speed soft jumpers enabled by combustion for motions through multiphase environments
Authors: Wang Haipeng , Yang Yang , Lin Guanzheng , Jiao Pengcheng , He Zhiguo
Published: November 2020

Soft robots have been widely studied to accomplish multifunctional on-land tasks in recent years. Here, we develop a type of combustion-enabled soft jumpers that are able to move through multiphase media (e.g. water–air multiphase) with a high-speed of ∼6 times body length per second on average and up to ∼9 times body length per second at most while the driving time is less than 0.5 s. The reported soft jumpers are driven by extremely expandable silicon-rubber membranes resulted in the combustion of oxygen-propane mixed gas. Experiments are conducted to investigate the multiphase jumping response of the soft jumpers with respect to the premixed gas ratio

r

of the combustion. Both numerical and analytical models are developed to investigate the jumping response in terms of the gas amount

A

, the premixed gas ratio

r

and the water depth

D

W

, and satisfactory agreements are obtained from the comparisons among the experimental, numerical and analytical results.
Low-power high-speed half-flux-quantum circuits driven by low bias voltages
Authors: Li Feng , Takeshita Yuto , Hasegawa Daiki , Tanaka Masamitsu , Yamashita Taro , Fujimaki Akira
Published: November 2020

Half-flux-quantum (HFQ) circuits store and propagate half-flux quanta. The basic circuit element is a 0-π SQUID, which is a superconducting quantum interference device with a conventional Josephson junction (0-junction) and a π-shifted ferromagnetic junction (π-junction). A 0-π SQUID achieves a small critical current in the absence of an external magnetic field, thus reducing power consumption. It is easy to set up 0-0-π SQUIDs with two 0-junctions and a π-junction which serves as a π phase-shifter. We simulated 0-0-π SQUID-based HFQ circuits driven by low bias voltages, referred to as LV-HFQ circuits. In these circuits, shunt resistors are not required for switching junctions because there is no hysteresis in the current–voltage characteristics of 0-0-π SQUIDs. We estimated the power consumption and maximum operating frequency of an HFQ Josephson transmission line based on 0-0-π SQUIDs. When operating at 43.5 GHz, the power dissipation of a single element composed of a 0-0-π SQUID and a bias resistor fell to about 0.165 nW when biased at 60 μV. The LV-HFQ circuit is potentially more power-efficient than all other currently available superconducting logic circuits.
Complex Berry curvature pair and quantum Hall admittance in non-Hermitian systems
Authors: Fan Annan , Huang Guang-Yao , Liang Shi-Dong
Published: November 2020

We propose complex Berry curvatures associated with the non-Hermitian Hamiltonian and its Hermitian adjoint and use these to reveal new physics in non-Hermitian systems. We give the complex Berry curvature and Berry phase for the two-dimensional non-Hermitian Dirac model. The imaginary part of the complex Berry phase induces susceptance so that the quantum Hall conductance is generalized to admittance for non-Hermitian systems. This implies that the non-Hermiticity of physical systems can induce intrinsic capacitive or inductive properties, depending on the non-Hermitian parameters. We analyze the complex energy band structures of the two-dimensional non-Hermitian Dirac model, determine the point and line gaps, and identify the conditions for their closure. We find that closure is associated with the exceptional degeneracy of the energy bands in the parameter space, which, in turn, is associated with topological phase transitions. In the continuum limit, we obtain the complex Berry phase in the parameter space.
The 𝐿^{𝑝} Dirichlet boundary problem for second order elliptic Systems with rough coefficients
Authors: Dindoš Martin , Hwang Sukjung , Mitrea Marius
Published: November 2020

Given a domain above a Lipschitz graph, we establish solvability results for strongly elliptic second-order systems in divergence-form, allowed to have lower-order (drift) terms, with

L
p

L^p

-boundary data for

p
p

near

2
2

(more precisely, in an interval of the form

(

2
−
ε
,

2
(
n
−
1
)

n
−
2

+
ε

)

\big (2-\varepsilon ,\frac {2(n-1)}{n-2}+\varepsilon \big )

for some small

ε
>
0

\varepsilon >0

). The main novel aspect of our result is that the coefficients of the operator do not have to be constant, or have very high regularity; instead they will satisfy a natural Carleson condition that has appeared first in the scalar case. A significant example of a system to which our result may be applied is the Lamé system for isotropic inhomogeneous materials. We show that our result applies to isotropic materials with Poisson ratio

ν
>
0.396

\nu >0.396

.

Dealing with genuine systems gives rise to substantial new challenges, absent in the scalar case. Among other things, there is no maximum principle for general elliptic systems, and the De Giorgi–Nash–Moser theory may also not apply. We are, nonetheless, successful in establishing estimates for the square-function and the nontangential maximal operator for the solutions of the elliptic system described earlier, and use these as alternative tools for proving

L
p

L^p

solvability results for

p
p

near

2
2

.
Orthogonal structure and orthogonal series in and on a double cone or a hyperboloid
Authors: Xu Yuan
Published: November 2020

We consider orthogonal polynomials on the surface of a double cone or a hyperboloid of revolution, either finite or infinite in axis direction, and on the solid domain bounded by such a surface and, when the surface is finite, by hyperplanes at the two ends. On each domain a family of orthogonal polynomials, related to the Gegebauer polynomials, is studied and shown to share two characteristic properties of spherical harmonics: they are eigenfunctions of a second order linear differential operator with eigenvalues depending only on the polynomial degree, and they satisfy an addition formula that provides a closed form formula for the reproducing kernel of the orthogonal projection operator. The addition formula leads to a convolution structure, which provides a powerful tool for studying the Fourier orthogonal series on these domains. Furthermore, another family of orthogonal polynomials, related to the Hermite polynomials, is defined and shown to be the limit of the first family, and their properties are derived accordingly.