bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of Silymarin in Silybi mariani fructus: Challenging the Analytical Performance of Benchtop vs. Handheld NIR Spectrometers on Whole Seeds
Authors: Mayr Sophia , Strasser Simon , Kirchler Christian G. , Meischl Florian , Stuppner Stefan , Beć Krzysztof B. , Grabska Justyna , Sturm Sonja , Stuppner Hermann , Popp Michael A. , Bonn Günther K. , Huck Christian W.
Published: January 2021

The content of the flavonolignan mixture silymarin and its individual components (silichristin, silidianin, silibinin A, silibinin B, isosilibinin A, and isosilibinin B) in whole and milled milk thistle seeds (Silybi mariani fructus) was analyzed with near-infrared spectroscopy. The analytical performance of one benchtop and two handheld near-infrared spectrometers was compared. Reference analysis was performed with HPLC following a Soxhlet extraction (European Pharmacopoeia) and a more resource-efficient ultrasonic extraction. The reliability of near-infrared spectral analysis determined through partial least squares regression models constructed independently for the spectral datasets obtained by the three spectrometers was as follows. The benchtop device NIRFlex N-500 performed the best both for milled and whole seeds with a root mean square error of CV between 0.01 and 0.17%. The handheld spectrometer MicroNIR 2200 as well as the microPHAZIR provided a similar
performance (root mean square error of CV between 0.01 and 0.18% and between 0.01 and 0.23%, respectively). We carried out quantum chemical simulation of near-infrared spectra of silichristin, silidianin, silibinin, and isosilibinin for interpretation of the results of spectral analysis. This provided understanding of the absorption regions meaningful for the calibration. Further, it helped to better separate how the chemical and physical properties of the samples affect the analysis. While the study demonstrated that milling of samples slightly improves the performance, it was deemed to be critical only for the analysis carried out with the microPHAZIR. This study evidenced that rapid and nondestructive quantification of silymarin and individual flavonolignans is possible with miniaturized near-infrared spectroscopy in whole milk thistle seeds.
Portal and hepatic vein embolization prior to major hepatectomy
Authors: Masthoff Max , Katou Shadi , Köhler Michael , Schindler Philipp , Heindel Walter , Wilms Christian , Schmidt Hartmut H. , Pascher Andreas , Struecker Benjamin , Wildgruber Moritz , Morgul Haluk
Published: January 2021

Purpose To analyze safety and effectiveness of simultaneous portal and hepatic vein embolization (PHVE) or sequential hepatic vein embolization (HVE) compared to portal vein embolization (PVE) for future remnant liver (FRL) hypertrophy prior to major hepatic surgery.

Methods Patients undergoing PVE, PHVE or HVE at our tertiary care center between 2018 and 2020 were retrospectively included. FRLV, standardized FRLV (sFRLV) and sFRLV growth rate per day were assessed via volumetry, as well as laboratory parameters.

Results 36 patients (f = 15, m = 21; median 64.5 y) were included, 16 patients received PHVE and 20 patients PVE, of which 4 received sequential HVE. Significant increase of FRLV was achieved with both PVE and PHVE compared to baseline (p < 0.0001). sFRLV growth rate did not significantly differ following PHVE (2.2 ± 1.2 %/d) or PVE (2.2 ± 1.7 %/d, p = 0.94). Left portal vein thrombosis (LPVT) was observed after PHVE in 6 patients and in 1 patient after PVE. Sequential HVE showed a considerably high growth rate of 1.42 ± 0.45 %/d after PVE.

Conclusion PHVE effectively induces FRL hypertrophy but yields comparable sFRLV to PVE. Sequential HVE further induces hypertrophy after insufficient growth due to PVE. Considering a potentially higher rate of LPVT after PHVE, PVE might be preferred in patients with moderate baseline sFRLV, with optional sequential HVE in non-sufficient responders.
Multidisciplinary approach to the complex treatment for non-cirrhotic portal hypertension – case-report-based discussion
Authors: Gairing Simon J. , Kloeckner Roman , Pitton Michael B. , Baumgart Janine , von Auer-Wegener Charis , Lang Hauke , Galle Peter R. , Foerster Friedrich , Schattenberg Jörn M.
Published: January 2021

Non-cirrhotic portal vein thrombosis (PVT) in patients with antiphospholipid syndrome (APS) is a rare complication, and the management has to be determined individually based on the extent and severity of the presentation. We report on a 37-year-old male patient with non-cirrhotic chronic PVT related to a severe thrombophilia, comprising APS, antithrombin-, factor V- and factor X-deficiency. Three years after the initial diagnosis of non-cirrhotic PVT, the patient presented with severe hemorrhagic shock related to acute bleeding from esophageal varices, requiring an emergency transjugular intrahepatic portosystemic stent shunt (TIPSS). TIPSS was revised after a recurrent bleeding episode due to insufficient reduction of the portal pressure. Additionally, embolization of the dilated V. coronaria ventriculi led to the regression of esophageal varices but resulted simultaneously in a left-sided portal hypertension (LSPH) with development of stomach wall and perisplenic varices. After a third episode of acute esophageal varices bleeding, a surgical distal splenorenal shunt (Warren shunt) was performed to reduce the LSPH. Despite anticoagulation with low molecular weight heparin and antithrombin substitution, endoluminal thrombosis led to a complete Warren shunt occlusion, aggravating the severe splenomegaly and pancytopenia. Finally, a partial spleen embolization (PSE) was performed. In the postinterventional course, leukocyte and platelet counts increased rapidly and the patient showed no further bleeding episodes. Overall, this complex course demonstrates the need for individual assessment of multimodal treatment options in non-cirrhotic portal hypertension. This young patient required triple modality porto-systemic pressure reduction (TIPSS, Warren shunt, PSE) and involved finely balanced anticoagulation and bleeding control.
Möglichkeiten der Vorhersage des Erfolgs einer Hörgeräteversorgung mittels des APHAB-Fragebogens
Authors: Thomas Max , Schönweiler Rainer , Löhler Jan
Published: January 2021

Hintergrund Die subjektive Bewertung einer Hörminderung durch Patienten erfolgt durch Fragebögen, z. B. den APHAB. Kumulierte Werte (Gesamtnutzen, Verbesserungsquotient) konnten bisher nicht individuell interpretiert werden, da es keine entsprechenden Daten gab. Diese zu schaffen und die Klärung der Frage, ob eine Perzentiltreue vor und nach einer HGV besteht, waren die Ziele der Studie.

Methode Aufgrund von 6861 Datensätzen von Patienten mit abgeschlossener HGV aus einer APHAB-Datenbank wurden für verschiedene Alters- sowie Perzentilgruppen der Gesamtnutzen und der Verbesserungsquotient berechnet und eine Heatmap erzeugt. Die Perzentiltreue der Individuen vor und nach einer HGV wurde mittels des Rangkoeffizienten nach Spearman ermittelt.

Ergebnisse Der Mittelwert des Verbesserungsquotienten lag bei 41,01 %. Jüngere Probanden (Durchschnitt 72,26 Jahre ± 11,86) hatten einen signifikant besseren Verbesserungsquotienten (44,36 %) als ältere (37,66 %). Der durchschnittliche Verbesserungsquotient nahm mit kleinerem APHAB-Score vor einer HGV in Bezug auf die Perzentilgruppen ab (23,22–52,07 %). Der Spearman-Korrelationskoeffizient für den APHAB-Nutzen war 0,285, die Effektstärke nach Cohen war klein. Der Gesamtnutzen korrelierte mit 0,582 und der Verbesserungsquotient mit 0,270 mit dem APHAB-Score vor einer HGV.

Schlussfolgerung Eine Perzentiltreue von Probanden vor und nach einer HGV war nicht nachweisbar. Es lassen sich aber Aussagen zum durchschnittlichen Erfolg nach dem Verbesserungsquotienten in Abhängigkeit von Perzentilgruppen und dem Lebensalter vom APHAB vor einer HGV erkennen. Alte Patienten mit einem geringen subjektiven Hörverlust profitierten am geringsten, junge mit einem hohen subjektiven Hörverlust am meisten von einer HGV.
Medicinal Plants in the Treatment of Depression: Evidence from Preclinical Studies
Authors: Moragrega Inés , Ríos José Luis
Published: January 2021

Medicinal plants and their extracts are natural remedies with enormous potential for treating various diseases, including depression and anxiety. In the case of depression, hundreds of plants have traditionally been used in folk medicine for generations. Different plant extracts and natural products have been analyzed as potential antidepressant agents with validated models to test for antidepressant-like effects in animals, although other complementary studies have also been employed. Most of these studies focus on the possible mediators implicated in these potential effects, with dopamine, serotonin, and noradrenaline being the principal neurotransmitters implicated, both through interference with receptors and with their metabolism by monoamino oxidases, as well as through neuro-endocrine and neuroprotective effects. There are approximately 650 reports of antidepressant-like medicinal plants in PubMed; 155 of them have been compiled in this review, with a relevant group yielding positive results. Saffron and turmeric are the most relevant species studied in both preclinical and clinical studies; St. Johnʼs wort or kava have also been tested extensively. To the best of our knowledge, no review to date has provided a comprehensive understanding of the biomolecular mechanisms of action of these herbs or of whether their potential effects could have real benefits. The purpose of this narrative review is to provide an update regarding medicinal plants from the year 2000 to the present to examine the therapeutic potential of these antidepressant-like plants in order to contribute to the development of new therapeutic methods to alleviate the tremendous burden that depression causes worldwide.
Novel Piperidine and 3,4-dihydro-2H-pyrrole Alkaloids from Tilia platyphyllos and Tilia cordata Flowers
Authors: Symma Nico , Bütergerds Marek , Sendker Jandirk , Petereit Frank , Hake Alexander , Düfer Martina , Hensel Andreas
Published: January 2021

Lime flowers, traditionally used for medical purposes for the treatment of symptoms of the common cold and mental stress, consist of the dried inflorescences including the floral bracts of Tilia cordata, Tilia platyphyllos, Tilia × vulgaris, or mixtures thereof. During phytochemical investigations, 6 different alkaloids – not described until now – were detected in T. cordata and T. platyphyllos flowers. They have been isolated and characterized as alkaloids with a dihydro-pyrrole and a piperidine substructure, respectively. Compounds 1a and 1b (tiliines A and B) are characterized as 2 diastereomers containing a 2-methyl-3,4-dihydro-2H-pyrrol-3-ol, connected via a C-10 alkyl chain to a O-glucosylated hydroquinone moiety. Compounds 2a and 2b (tiliamines A and B) are diastereomers of a 2-methyl-substituted piperidin-3-ol, coupled via a C-9 alkyl chain again to an O-glucosylated hydroquinone moiety. Compounds 3a and 3b (tilacetines A and B) are 3-O-acetylated derivatives of tiliamines. Quantification of the 6 alkaloids by HPLC-ESI-qTOF analysis indicated the presence of all alkaloids in T. cordata flowers and T. platyphyllos flowers, bracts, and leaves, with tiliines A and B and tilacetines A and B being the major compounds. Acetone/water turned out be the best extraction solvent for the alkaloids, but ethanol and ethanol/water mixtures also can be used for effective extraction. Furthermore, the alkaloids are found in hot water extracts, which are typically used in the traditional medicine.
Recent Advances in the Development of Catalytic Methods that Construct Medium-Ring Lactams, Partially Saturated Benzazepines and Their Derivatives
Authors: Driver Tom G. , Mazumdar Wrickban
Published: January 2021

Recent catalytic methods to construct medium-sized lactams­ and partially saturated benzazepines and their derivatives are surveyed. The review is divided into the following sections:

1 Introduction

2 Non-Transition-Metal-Catalyzed Reactions

2.1 Beckmann Rearrangement

2.2 Non-Beckmann Rearrangement Reactions

2.3 Multicomponent reactions

3 Transition-Metal-Catalyzed Reactions

3.1 Gold-Catalyzed Reactions to Access Medium-Sized N-Hetero­cycles

3.2 Reactions Involving a Metal η3-Complex Catalytic Intermediate

3.3 Transition-Metal-Catalyzed Reactions of Strained Cycloalkanes

4 Conclusions
Complementary and Regioselective Synthesis of Isomeric 3-[Isoxazol-3(or 5)-yl]indoles from β-Ethylthio-β-indolyl-α,β-unsaturated Ketones
Authors: Yu Haifeng , Wang Wenju , Wang Kehua , Zhang Xue
Published: January 2021

A simple and efficient method for the complementary and regioselective synthesis of isomeric 3-(isoxazol-5-yl)indoles and 3-(isoxazol-3-yl)indoles has been developed by the regioselective cyclocondensation reaction of β-ethylthio-β-indolyl-α,β-unsaturated ketones and hydroxylamine hydrochloride. It was found that the cyclocondensation reaction in the presence of excess NaOEt in refluxing EtOH gives 3-(isoxazol-5-yl)indoles in good yields, whereas using NaOAc in boiling AcOH gives 3-(isoxazol-3-yl)indoles in good yields.
Spinal Cord Stimulation for Chronic Refractory Neuropathic Pain: A Technical Note Initial Experience of Two cases
Authors: Srivastava Sanjeev , Goyal Pawan , Sharma Anurag , Rajan Sanjay K. , Gupta Aditya
Published: January 2021

Spinal cord stimulation is an established procedure for relieving chronic neuropathic pain conditions. Although it has been over five decades since the first spinal cord stimulation (SCS) was developed, it has only been used in a few cases in India. It is primarily based on the “Gate Theory” of pain. The mechanism of its action is not exactly clear, but reports have suggested that it plays the main role in selectively stimulating the large diameter pain fibers in the dorsal aspect of spinal cord. SCS procedure involves a very careful case selection, and current evidence suggests that only a few conditions of chronic refractory neuropathic pain are its established indications. In these patients too, the efficacy rate remains around 50 to 75%. The overall pain relief observed is around 50% decrease in visual analog scale (VAS) scores. It is a technically simple procedure involving placement of electrodes over the dorsal aspect of spinal cord in the epidural space. The procedure is a staged one in which trial lead electrodes are first implanted and stimulated with an external pulse generator (EPG). If the trial is successful and patient has acceptable pain relief over 1 week of stimulation at various settings, the patient undergoes the permanent implantation of electrodes at the same position. The permanent electrodes are then stimulated by an implantable pulse generator (IPG) in the subcutaneous pocket (abdominal or gluteal). Complications are rare and are more related to hardware like lead migration and breakage. Since it is does not damage the cord per se, its acceptance as a procedure for pain is known quite well in the Western world. Its availability and cost of implants is the major hurdle in its use in a developing nation like India. Here, we present a technical note and our experience of two cases of thoracic spinal cord stimulation for chronic neuropathic pain at our institution.
Complications of Costal Cartilage Asian Rhinoplasty and Their Management
Authors: Won Tae-Bin , Jin Hong-Ryul
Published: January 2021

The abundance, biocompatibility, and versatility of autologous costal cartilage allow rhinoplasty surgeons to perform an array of maneuvers needed to successfully manage cases that require an ample source of grafting materials. Hence, there has been a steady increase in the use of costal cartilage in Asian rhinoplasty. Despite its many advantages, autologous costal cartilage rhinoplasty is also associated with complications, which include warping, infection, and displacement, as well as donor-site morbidity issues such as pneumothorax, pain, and chest scars. Many of these can be minimized by adhering to the recommended techniques. In this review, operative techniques that focus on the prevention and management of complications associated with the use of autologous costal cartilage are presented.
Patella Fracture Repair Using Multiple Fixation Modalities in a Dog
Authors: Chau Lincoln , Wilson Lance
Published: January 2021

The aim of this study was to describe the clinical use of a titanium locking plate and screws as an adjunct for the surgical treatment of an open, transverse, mid-body patellar fracture. A 2-year-old crossbreed dog was diagnosed with an open, transverse, mid-body patellar fracture. Initial fracture reduction and compression were achieved with two parallel Kirschner wires and a figure of eight tension band wire. This was followed by a titanium locking plate and screws placed on the cranial aspect of the patella. A transarticular circular external skeletal fixator was used as an additional augmentation for 5 weeks. Wire failure was noted in the transarticular circular external skeletal fixator at 10 days postoperation, necessitating wire replacement. Complete return to previous activity level and progressive radiographic osseous union were observed 8 weeks after surgery. Breakage of the Kirschner wires at the proximal pole of the patella was noted 3 years after surgery and explantation of all implants was performed. Recheck evaluation at 8 months after explantation confirmed full return to athletic function. This case report described the clinical use of a locking plate and screws as an adjunct for transverse patellar fracture repair and its long-term functional outcome.
Cardiac Fibroma with Asymptomatic Ventricular Arrhythmia in an Adolescent with Gorlin's Syndrome
Authors: Menon Dipika , Dentel John N. , Sanil Yamuna , Lawrence David
Published: January 2021

Nevoid basal cell carcinoma syndrome (NBCCS), also referred to as Gorlin's syndrome, is an autosomal dominant inherited condition that predisposes affected individuals to various tumors such as cardiac fibromas. Though technically benign, cardiac fibromas may result in malignant arrhythmias and sudden death. The pertinent literature pertaining to pediatric cases of cardiac fibromas and their clinical features were reviewed. We present the case of an asymptomatic teenage with de novo NBCCS who was diagnosed with both NBCCS and cardiac fibroma later in life. The patient was noted to have clinically significant ventricular arrhythmias that were eliminated with tumor resection. There are no established best practice guidelines for the management of cardiac fibromas in patients with NBCCS. Given the risk of sudden arrhythmic death, the presence of ventricular arrhythmias should prompt strong consideration of tumor resection.
Controlling the Film Microstructure in Organic Thermoelectrics
Authors: Xiong Miao , Wang Jie-Yu , Pei Jian
Published: January 2021

Doping is a vital method to increase the charge carrier concentration of conjugated polymers, thus improving the performance of organic electronic devices. However, the introduction of dopants may cause phase separation. The miscibility of dopants and polymers as well as the doping-induced microstructure change are always the barriers in the way to further enhance the thermoelectrical performance. Here, recent research studies about the influence of molecular doping on the microstructures of conjugated polymers are summarized, with an emphasis on the n-type doping. Highlighted topics include how to control the distribution and density of dopants within the conjugated polymers by modulating the polymer structure, dopant structure, and solution-processing method. The strong Coulombic interactions between dopants and polymers as well as the heterogeneous doping process of polymers can hinder the polymer film to achieve better miscibility of dopants/polymer and further loading of the charge carriers. Recent developments and breakthroughs provide guidance to control the film microstructures in the doping process and achieve high-performance thermoelectrical materials.
Searching for Utopia, the Challenge of Standardized Medical Nutrition Therapy Prescription in Gestational Diabetes Mellitus Management: A Critical Review
Authors: Meloncelli Nina , Wilkinson Shelley A. , de Jersey Susan
Published: January 2021

Gestational diabetes mellitus (GDM) is a common pregnancy disorder and the incidence is increasing worldwide. GDM is associated with adverse maternal outcomes which may be reduced with proper management. Lifestyle modification in the form of medical nutrition therapy and physical activity, as well as self-monitoring of blood glucose levels, is the cornerstone of GDM management. Inevitably, the search for the “ultimate” diet prescription has been ongoing. Identifying the amount and type of carbohydrate to maintain blood glucose levels below targets while balancing the nutritional requirements of pregnancy and achieving gestational weight gain within recommendations is challenging. Recent developments in the area of the gut microbiota and its impact on glycemic response add another layer of complexity to the success of medical nutrition therapy. This review critically explores the challenges to dietary prescription for GDM and why utopia may never be found.
Prevalence and Risk Factors of Premature Ovarian Insufficiency/Early Menopause
Authors: Giri Rinky , Vincent Amanda J.
Published: January 2021

Premature ovarian insufficiency (POI) and early menopause, defined as loss of ovarian activity prior to 40 years or menopause between the ages of 40 and 45 years, respectively, is associated with significant adverse health impacts. Recent data indicate that the prevalence of POI and early menopause is greater than was previously thought, affecting more than 10% of women. Biopsychosocial risk factors including genetic, autoimmune, reproductive, lifestyle, early-life, social/environmental, and iatrogenic have been associated with POI/early menopause or earlier age at menopause. However, establishing a causal role and the underlying mechanisms remains elusive. Understanding and clarification of these risk factors will facilitate prevention and risk minimization strategies to optimize women's health.
Detecting prediction limit of marked point processes using constrained random shuffle surrogate data
Authors: Shimada Yutaka , Yamamoto Kohei , Ikeguchi Tohru
Published: January 2021

Marked point processes refer to time series of discrete events with additional information about the events. Seismic activities, neural activities, and price movements in financial markets are typical examples of marked point process data. In this paper, we propose a method for investigating the prediction limits of marked point process data, where random shuffle surrogate data with time window constraints are proposed and utilized to estimate the prediction limits. We applied the proposed method to the marked point process data obtained from several dynamical systems and investigated the relationship between the largest Lyapunov exponent and the prediction limit estimated by the proposed method. The results revealed a positive correlation between the reciprocal of the estimated prediction limit and the largest Lyapunov exponent of the underlying dynamical systems in marked point processes.
A novel algorithm for implementing time-frequency transform with low computation
Authors: Zhang Yijiao , Tian Shulin , Pan Huiqing , Qiu Duyu , Guo Lianping
Published: January 2021

In this paper, a novel algorithm called two-dimensional sliding fast Fourier transform (2D SFFT) algorithm is proposed. This algorithm organizes one-dimensional data in two dimensions and calculates the spectrum of current data by using the existing spectrum and new collected data. The algorithm formula and accurate simulation results show the following: first, the computation required by the proposed 2D SFFT algorithm is lower than that required by the traditional sliding discrete Fourier transform algorithm when the sliding rate is larger than or equal to 4/M, where M is the sequence length. Moreover, the computation required by the proposed 2D SFFT algorithm is lower than that required by the fast Fourier transform (FFT) algorithm when the sliding rate is less than or equal to 6.25%. Finally, the error between the spectrum calculated by the 2D SFFT and FFT algorithms is less than 10−10. The 2D SFFT algorithm is used to increase the power of the ultra-short pulse, which is initially invisible in the frequency-domain window of the mixed-domain oscilloscope. Therefore, the 100% probability of intercept of the mixed-domain oscilloscope is lower.
Multifunctionality in a reservoir computer
Authors: Flynn Andrew , Tsachouridis Vassilios A. , Amann Andreas
Published: January 2021

Multifunctionality is a well observed phenomenological feature of biological neural networks and considered to be of fundamental importance to the survival of certain species over time. These multifunctional neural networks are capable of performing more than one task without changing any network connections. In this paper, we investigate how this neurological idiosyncrasy can be achieved in an artificial setting with a modern machine learning paradigm known as “reservoir computing.” A training technique is designed to enable a reservoir computer to perform tasks of a multifunctional nature. We explore the critical effects that changes in certain parameters can have on the reservoir computers’ ability to express multifunctionality. We also expose the existence of several “untrained attractors”; attractors that dwell within the prediction state space of the reservoir computer were not part of the training. We conduct a bifurcation analysis of these untrained attractors and discuss the implications of our results.
A state observer for the computational network model of neural populations
Authors: Sun Cheng-Xia , Liu Xian
Published: January 2021

A state observer plays a vital role in the design of state feedback neuromodulation schemes used to prevent and treat neurological or psychiatric disorders. This paper aims to design a state observer to reconstruct all unmeasured states of the computational network model of neural populations that replicates patterns seen on the electroencephalogram by using the model inputs and outputs, as the theoretical basis for designing state feedback neuromodulation clinical schemes. The feasibility problem of linear matrix inequality conditions, which is the most important one for observer design of the computational network model of neural populations, is solved by using the input–output stability theory and the Lurie system theory. The observer matrices of the designed observer are formed by the optimal solution of the linear matrix inequality conditions. An illustrative example shows that the observer can simultaneously reproduce internal state variables of normal and lesion populations of the computational network model of neural populations under the background of focal origin brain dysfunction, and the designed observer has certain robustness toward input uncertainty and measurement noise. To the best of our knowledge, no observers have previously been designed for the computational network model of neural populations. The design of state feedback neuromodulation schemes based on the computational network model of neural populations is a new direction in the field of computational neuroscience.
X-ray powder diffraction in reflection geometry on multi-beam kJ-type laser facilities
Authors: Denoeud A. , Hernandez J.-A. , Vinci T. , Benuzzi-Mounaix A. , Brygoo S. , Berlioux A. , Lefevre F. , Sollier A. , Videau L. , Ravasio A. , Guarguaglini M. , Duthoit L. , Loison D. , Brambrink E.
Published: January 2021

An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been developed at the LULI2000 laser facility. X-ray diffraction is performed in reflection geometry from a quasi-monochromatic laser-generated plasma x-ray source. In comparison to a transmission geometry setup, this configuration allows us to probe only a small portion of the compressed sample, as well as to shield the detectors against the x-rays generated by the laser–plasma interaction on the front side of the target. Thus, this new platform facilitates probing of spatially and temporarily uniform thermodynamic conditions and enables us to study samples of a large range of atomic numbers, thicknesses, and compression dynamics. As a proof-of-concept, we report direct structural measurements of the bcc–hcp transition both in shock and ramp-compressed polycrystalline iron with diffraction signals recorded between 2θ ∼ 30° and ∼150°. In parallel, the pressure and temperature history of probed samples is measured by rear-side visible diagnostics (velocimetry and pyrometry).
Broadband high-energy resolution hard x-ray spectroscopy using transition edge sensors at SPring-8
Authors: Yamada Shinya , Ichinohe Yuto , Tatsuno Hideyuki , Hayakawa Ryota , Suda Hirotaka , Ohashi Takaya , Ishisaki Yoshitaka , Uruga Tomoya , Sekizawa Oki , Nitta Kiyofumi , Takahashi Yoshio , Itai Takaaki , Suga Hiroki , Nagasawa Makoto , Tanaka Masato , Kurisu Minako , Hashimoto Tadashi , Bennett Douglas , Denison Ed , Doriese William Bertrand , Durkin Malcolm , Fowler Joseph , O’Neil Galen , Morgan Kelsey , Schmidt Dan , Swetz Daniel , Ullom Joel , Vale Leila , Okada Shinji , Okumura Takuma , Azuma Toshiyuki , Tamagawa Toru , Isobe Tadaaki , Kohjiro Satoshi , Noda Hirofumi , Tanaka Keigo , Taguchi Akimichi , Imai Yuki , Sato Kosuke , Hayashi Tasuku , Kashiwabara Teruhiko , Sakata Kohei
Published: January 2021

We have succeeded in operating a transition-edge sensor (TES) spectrometer and evaluating its performance at the SPring-8 synchrotron x-ray light source. The TES spectrometer consists of a 240 pixel National Institute of Standards and Technology (NIST) TES system, and 220 pixels are operated simultaneously with an energy resolution of 4 eV at 6 keV at a rate of ∼1 c/s pixel−1. The tolerance for high count rates is evaluated in terms of energy resolution and live time fraction, leading to an empirical compromise of ∼2 × 103 c/s (all pixels) with an energy resolution of 5 eV at 6 keV. By utilizing the TES’s wideband spectroscopic capability, simultaneous multi-element analysis is demonstrated for a standard sample. We conducted x-ray absorption near-edge structure (XANES) analysis in fluorescence mode using the TES spectrometer. The excellent energy resolution of the TES enabled us to detect weak fluorescence lines from dilute samples and trace elements that have previously been difficult to resolve due to the nearly overlapping emission lines of other dominant elements. The neighboring lines of As Kα and Pb Lα2 of the standard sample were clearly resolved, and the XANES of Pb Lα2 was obtained. Moreover, the x-ray spectrum from the small amount of Fe in aerosols was distinguished from the spectrum of a blank target, which helps us to understand the targets and the environment. These results are the first important step for the application of high resolution TES-based spectroscopy at hard x-ray synchrotron facilities.
Neural modeling of antisaccade performance of healthy controls and early Huntington's disease patients
Authors: Cutsuridis Vassilis , Jiang Shouyong , Dunn Matt J. , Rosser Anne , Brawn James , Erichsen Jonathan T.
Published: January 2021

Huntington's disease (HD), a genetically determined neurodegenerative disease, is positively correlated with eye movement abnormalities in decision making. The antisaccade conflict paradigm has been widely used to study response inhibition in eye movements, and reliable performance deficits in HD subjects have been observed, including a greater number and timing of direction errors. We recorded the error rates and response latencies of early HD patients and healthy age-matched controls performing the mirror antisaccade task. HD participants displayed slower and more variable antisaccade latencies and increased error rates relative to healthy controls. A competitive accumulator-to-threshold neural model was then employed to quantitatively simulate the controls' and patients' reaction latencies and error rates and uncover the mechanisms giving rise to the observed HD antisaccade deficits. Our simulations showed that (1) a more gradual and noisy rate of accumulation of evidence by HD patients is responsible for the observed prolonged and more variable antisaccade latencies in early HD; (2) the confidence level of early HD patients making a decision is unaffected by the disease; and (3) the antisaccade performance of healthy controls and early HD patients is the end product of a neural lateral competition (inhibition) between a correct and an erroneous decision process, and not the end product of a third top-down stop signal suppressing the erroneous decision process as many have speculated.
Nonlocal symmetry of CMA generates ASD Ricci-flat metric with no Killing vectors
Authors: Sheftel M. B.
Published: January 2021

The complex Monge–Ampère (CMA) equation in a two-component form is treated as a bi-Hamiltonian system. I present explicitly the first nonlocal symmetry flow in each of the two hierarchies of this system. An invariant solution of the CMA equation with respect to these nonlocal symmetries is constructed, which, being a noninvariant solution in the usual sense, does not undergo symmetry reduction in the number of independent variables. I also construct the corresponding four-dimensional anti-self-dual Ricci-flat metric with either the Euclidean or neutral signature. It admits no Killing vectors, which is one of the characteristic features of the famous gravitational instanton K3. For the metric with the Euclidean signature, relevant for gravitational instantons, I explicitly calculate the Levi-Civita connection one-forms and the Riemann curvature tensor.
Compressible subsonic cavity flow in a nozzle
Authors: Wang Xiaohui
Published: January 2021

This paper concerns the existence and uniqueness of a two-dimensional compressible subsonic cavity flow behind a given obstacle with a free surface in an infinitely long nozzle. More precisely, for any given atmospheric pressure pe > 0, we first show that there exists a critical value mcr for the incoming mass flux m0 such that if m0 < mcr, then there exists a unique smooth subsonic cavity flow behind the given obstacle, and the free surface initiates smoothly from the vertex of the obstacle and goes to infinity at the far field. Second, we establish some fundamental properties of the cavity flow, such as the positivity of the horizontal velocity and the asymptotic behavior of the flow at the far field. Finally, we obtain that the vertical velocity is positive under the corresponding assumptions on the upper nozzle wall and the upper surface of the obstacle.
Collision of a hard ball with singular points of the boundary
Authors: Attarchi H. , Bunimovich L. A.
Published: January 2021

Recently, physical billiards were introduced where a moving particle is a hard sphere rather than a point as in standard mathematical billiards. It has been shown that in the same billiard tables, the physical billiards may have totally different dynamics than mathematical billiards. This difference appears if the boundary of a billiard table has visible singularities (internal corners if the billiard table is two-dimensional); i.e., the particle may collide with these singular points. Here, we consider the collision of a hard ball with a visible singular point and demonstrate that the motion of the smooth ball after collision with a visible singular point is indeed the one that was used in the studies of physical billiards. Therefore, such collision is equivalent to the elastic reflection of hard ball’s center off a sphere with the center at the singular point and the same radius as the radius of the moving particle. However, a ball could be rough, not smooth. In difference with a smooth ball, a rough ball also acquires rotation after reflection off a point of the boundary, which leads to more complicated dynamics.
Laser transport and backscatter in low-density SiO2 and Ta2O5 foams
Authors: Mariscal D. A. , Jones O. S. , Berger R. L. , Patankar S. , Baker K. L. , Baumann T. F. , Biener M. M. , Goyon C. , Pollock B. B. , Moody J. D. , Strozzi D. J.
Published: January 2021

Experiments using a single 527 nm wavelength beam interacting with sub- and supercritical density SiO2 and Ta2O5 foams examined laser propagation and backscatter from laser–plasma instabilities such as Stimulated Brillouin Scattering (SBS). Two densities of each material were examined, and multiple diagnostics were used to characterize the propagation and backscatter. For 5 mg/cc SiO2 (ne/nc = 0.375), the laser propagation distance was well approximated by treating the foam as a gas. However, for the 2 mg/cc SiO2 foam (ne/nc = 0.15), the same model over-predicts the propagation distance by ∼40%. Existing analytical theories on propagation through subcritical foams were able to account for this difference. The laser heat wave propagated ∼1/2 as far in Ta2O5 than SiO2 foams with similar electron density. We showed that this difference is due to the increased radiation losses in the higher Z foam. The fraction of backscattered light scales linearly with incident laser intensity for the range of intensities examined. Ta2O5 foams had significantly lower levels of backscatter (1–3%) than the SiO2 (4–8%), which is consistent with estimates of large Landau damping due to the presence of the oxygen atoms. The measured fraction of SBS backscattered laser energy for a 2 mg/cc SiO2 foam shot was ∼4 times lower than predicted by simulations assuming a gas-like foam. We found that we needed to assume increased ion heating such that Ti/Te ∼ 1.2–1.5 in the plasma to agree with the measured SBS reflectivity. Analytical models of laser-heated foams predict preferential heating of the ions as has been observed in previous experiments.
Raman spectra and elastic light scattering dynamics of V3O5 across insulator–metal transition
Authors: Lysenko Sergiy , Rúa Armando , Kumar Nardeep , Lu Junqiang , Yan Jia-An , Theran Larry , Echeverria Karla , Ramos Leonardo , Goenaga Gabriel , Hernández-Rivera Samuel P. , Fernández Félix E.
Published: January 2021

The observation of Raman-active mode softening is a powerful tool to understand phase transition mechanisms in solids. The evolution of the phonon spectrum of technologically important correlated oxide V3O5 attracts much attention for the steady-state regime and for ultrashort temporal scales since thermal contribution to the insulator-to-metal (IMT) transition is excluded during the first few picoseconds. Here, we show theoretical modeling of V3O5 phonon spectrum and experiment. It is shown that the IMT is a first-order phase transition. Photoinduced transition was observed by a elastic light scattering technique, showing the principal difference in V3O5 surface dynamics across IMT for thermally and ultrafast light-induced phase transitions. The ultrafast IMT is accompanied primarily by short-range optical phonon interactions with a negligible contribution by acoustic phonons, while the acoustic phonons provide a key contribution to the transformation of surface geometry upon thermally induced IMT. Scattering imaging of surface autocorrelation function upon IMT shows the rise of optical homogeneity in the lateral direction of the surface in the steady-state regime and on a subpicosecond time scale.
Bipolar electric field-induced nucleation of magnetic domains with 90° domain walls
Authors: Antipin K. S. , Gareev T. T. , Myasnikov N. V. , Nikolaeva E. P. , Pyatakov A. P.
Published: January 2021

Magnetoelectric effects in multiferroics give an opportunity to control intrinsic magnetic ordering with an external electric field. In this paper, we demonstrate the emergence of magnetic domains in the local electric field generated by cantilever tip in the (110)-oriented iron garnet film at room temperature. We show that the in-plane magnetized phase observed in this film enables the nucleation of the magnetic domain with 90°domain walls both at positively and negatively biased tip. The found bipolarity of the effect is in contrast to the unipolar nucleation of a bubble domain in the case of a conventional 180° domain wall. The experimental and theoretical studies reveal the mechanism of electric field generation of the 90° magnetic domain and its dependence on the domain wall's chirality.
Sodium-storage behavior of electron-rich element-doped amorphous carbon
Authors: Li Yuqian , Zhang Liyuan , Wang Xiuli , Xia Xinhui , Xie Dong , Gu Changdong , Tu Jiangping
Published: January 2021

In recent years, sodium ion batteries (SIBs) have been widely investigated due to limited lithium resources. Though sodium and lithium elements have similar physical and chemical properties, some decently performing anodes of lithium ion batteries are problematic in SIBs. Hence, it is of great importance to develop suitable anodes for SIBs. In recent works, doped amorphous carbon has been considered a prospective and serviceable anode for the storage of sodium. Nevertheless, there is no commonly accepted explanation for the sodium storage mechanism and doping effect of doped carbon to explain why doping can improve the sodium-storage performance in SIBs. In this study, sodium-storage behavior in electron-rich, element-modified, amorphous carbon is addressed, considering N and P. The affinity of N-doped amorphous carbon is identified by calculating the electron distributions of the N-doped structures. Furthermore, the adsorption energies of sodium in the P-doped amorphous carbon systems are analyzed to elucidate the storage behavior of doping. From the above analysis, the internal structure of co-doped carbon is characterized and pyrrolic N and P-O structures reveal excellent sodium-storage performance. Consequently, hydrothermal treatment is designed to build the precursor of the required P-O structure. Based on the sodium-storage theory, a carbon anode doped with dual electron-rich elements is synthesized successfully, which shows enhanced electrochemical performances in terms of cycle life and capacity in batteries. As a result, these research results fill the theoretical gap of the sodium-storage behavior of electron-rich, element-doped, amorphous carbon and provide the experimental basis for its application.
The effect of localized strain on the electrical characteristics of curved carbon nanotubes
Authors: Zhu Zhenxing , Wei Nan , Gao Jun , Jiang Yaxin , Peng Lianmao , Wei Fei
Published: January 2021

Carbon nanotubes (CNTs) are the emerging alternative for silicon for developing miniatured electromechanical devices in the More than Moore's era. But, the inconsistent pitch distances among the aligned CNTs have limited their outstanding performances. Except for the intertube overlapping, the curved morphology is an important but often ignored factor for the attractive CNTs under van der Waals interaction. Here, we have synthesized a clean and curved CNT structure with a definite curvature radius by introducing micro perturbation. Electrical measurement has demonstrated that the curved structure will limit the on/off ratio by orders of magnitude but can maintain a high output delivery in transistors. This is attributed to the resistance induced by the localized strain and the extra current delivery capability of the inner walls, which can be well explained by the energy band diagram model. Among the curved CNTs, incommensurate double walled CNTs of higher diameter difference are the optimal candidates for delivering a high current output by limiting intertube charge transfer. Our demonstrations and analysis have highlighted the importance of controlling both the chiral structures and morphology of CNTs for the applications of high-performance carbon-based electronics.
Curvature-induced bandgap reduction in TiO2 double-walled nanotubes
Authors: An Jiao , Wanaguru Prabath , Tan Zhi , Peng Yuting , Zhang Qiming
Published: January 2021

The geometric and electronic properties of the double-walled nanotubes (DWNTs), constructed by the two coaxial single-walled nanotubes (SWNTs) rolling the hexagonal titanium dioxide (TiO2) nanosheet along with the armchair (ac-) and the zigzag (zz-) directions, have been investigated systematically using the methods based on the density functional theory. For the optimized structures, the bandgap values of the TiO2 DWNTs are significantly reduced from that of the constituent SWNTs, falling in the visible light range. Further detailed analysis reveals that the reduction is caused by the band misalignment due to the different curvatures of the inner and outer TiO2 SWNTs.
Mechanistic understanding of entanglement and heralding in cascade emitters
Authors: N. Avanaki Kobra , Schatz George C.
Published: January 2021

Semiconductor quantum light sources are favorable for a wide range of quantum photonic tasks, particularly quantum computing and quantum information processing. Here, we theoretically investigate the properties of quantum emitters as a source of entangled photons with practical quantum properties including heralding of on-demand single photons. Through the theoretical analysis, we characterize the properties of a cascade (biexciton) emitter, including (1) studies of single-photon purity, (2) investigating the first- and second-order correlation functions, and (3) determining the Schmidt number of the entangled photons. The analytical expression derived for the Schmidt number of the cascade emitters reveals a strong dependence on the ratio of decay rates of the first and second photons. Looking into the joint spectral density of the generated biphotons, we show how the purity and degree of entanglement are connected to the production of heralded single photons. Our model is further developed to include polarization effects, fine structure splitting, and the emission delay between the exciton and biexciton emission. The extended model offers more details about the underlying mechanism of entangled photon production, and it provides additional degrees of freedom for manipulating the system and characterizing purity of the output photon. The theoretical investigations and the analysis provide a cornerstone for the experimental design and engineering of on-demand single photons.
Electrically driven frequency blue-chirped emission in Fabry–Perot cavity quantum cascade laser at room temperature
Authors: Chin S. , Mitev V. , Giraud E. , Maulini R. , Blaser S. , Boiko D. L.
Published: January 2021

We present a method to produce a fast frequency swept laser emission from a monolithic mid-infrared laser. A commercially available Fabry–Pérot cavity quantum cascade laser (QCL) operating at a wavelength of 8.15 μm was electrically driven by a current pulse with a 10 μs duration and a slow front rising time of ∼2 μs. Due to the switching of the lasing emission from the vertical to the diagonal transition in the QCL and a strong quantum-confined Stark effect energy shift of the diagonal transition, the frequency of the emitted light was blue-shifting as the injection current continues to raise above the threshold. The temporal evolution of the laser spectrum was measured by a high-resolution step-scan Fourier transform infrared spectrometer. The blue-chirped emission was strongly influenced by the heatsink temperature due to the high thermal sensitivity of the threshold current and slope efficiency. By optimizing carefully the QCL operating temperature and the amplitude of the current pulse, we demonstrate a high-speed self-sweeping laser emission under room temperature operation conditions, reaching the spectral tuning range of ∼25 cm−1 within 1.8 μs.