bluuebunny/crossref_metadata_2025 huggingface dataset:
Topologically stable helices in exchange coupled rare-earth/rare-earth multilayer with superspin-glass like ordering
Authors: Ye Jingfan , Baldauf Thomas , Mattauch Stefan , Paul Neelima , Paul Amitesh
Published: September 2019

Existence of 2π-planar domain walls (DWs) are often reported for transition metal-rare-earth (TM/RE) layered systems. The magnetization process of such two-dimensional randomly anisotropical system in the form of 2π-DWs is directly correlated with topologically stable helices. Here, instead of TM/RE, we have investigated [Dy/Tb]10 multilayers involving two different anisotropic layers of rare-earth/rare-earth (RE/RE). Using magnetization and susceptibility as function of temperature along with thermo-remanent magnetization measurements we have confirmed superspin-glass type of behavior within this RE/RE system. Additionally, an exchange bias field up to –0.88 kOe (–88 mT) was also revealed for such rare-earth based multilayers. Interestingly, using detailed analysis of the polarized neutron reflectometry profiles, we find evidences of superimposed helical magnetic configurations within both materials of Dy and Tb associated with spin-frustrated interfaces. Furthermore, magnetization fluctuations around the mean magnetization from vertically uncorrelated domains were observed with polarized off-specular neutron scattering. We believe that coexistence of helical ground states with superspin-glass-like ordering are fundamentally instrumental for topologically stability in RE/RE systems, which in principle, can be exploited in all-spin-based technology.
Cu–NHC azide complex: synthesis and reactivity
Authors: Trose Michael , Nahra Fady , Cordes David B. , Slawin Alexandra M. Z. , Cazin Catherine S. J.
Published: September 2019

The first example of a NHC-based copper azide complex is reported. Its reactivity was investigated with various reagents affording 8 new complexes.
AB loop engineered ferritin nanocages for drug loading under benign experimental conditions
Authors: Wang Wenming , Wang Lele , Li Guobang , Zhao Guanghua , Zhao Xuan , Wang Hongfei
Published: September 2019

Selective removal of several residues from the AB loop of ferritin makes it more suitable for drug loading under benign experimental conditions.
Intercepted dehomologation of aldoses by N-heterocyclic carbene catalysis – a novel transformation in carbohydrate chemistry
Authors: Draskovits Markus , Kalaus Hubert , Stanetty Christian , Mihovilovic Marko D.
Published: September 2019

Examples of strong substrate governance and tuning of selectivity between two borderline scenarios by successful catalyst design are reported.
Facile synthesis of crystalline RuSe2 nanoparticles as a novel pseudocapacitive electrode material for supercapacitors
Authors: Yun Xiaoru , Wu Shanglin , Li Jingying , Li Linshuo , Zhou Ji , Lu Pengcheng , Tang Heng , Zhu Yirong
Published: September 2019

Crystalline RuSe2 nanoparticles were firstly utilized as a pseudocapacitive electrode material for supercapacitors, and superior capacitive behaviors were observed.
LAMP-generated H+ ions-induced dimer i-motif as signal transducer for ultrasensitive electrochemical detection of DNA
Authors: Hua Xiaoyu , Yang Enfen , Yang Wenting , Yuan Ruo , Xu Wenju
Published: September 2019

An electrochemical biosensor was developed based on a LAMP-H+-induced dimer i-motif coupled with ExoIII-assisted DNA walking for signal transduction and amplification.
In vivo ratiometric tracking of endogenous β-galactosidase activity using an activatable near-infrared fluorescent probe
Authors: Shi Limin , Yan Chenxu , Ma Yiyu , Wang Ting , Guo Zhiqian , Zhu Wei-Hong
Published: September 2019

Herein, we exemplify BODIPY-βgal as a ratiometric light-up NIR probe for the quantitative sensing of endogenous β-gal distribution in living cells, and real-time tracking of β-gal activity in tumor-bearing nude mice.
The key effects of polymorphism during PbII uptake by calcite and aragonite
Authors: Di Lorenzo Fulvio , Ruiz-Agudo Cristina , Churakov Sergey V.
Published: September 2019

The efficiency of Pb uptake by CaCO3 is different for calcite and aragonite due to surface passivation.
Reply to the ‘Comment on “Penicillin's catalytic mechanism revealed by inelastic neutrons and quantum chemical theory”’ by S. A. Glover, Phys. Chem. Chem. Phys., 2019, 21, 18012
Authors: Mucsi Zoltan , Chass Gregory A. , Csizmadia Imre G.
Published: September 2019

Herein we comparatively comment on the molecular metric ‘amidicity’, a descriptor of amide reactivity, and differing methods to determining it; with focus on lactam-rings.
A novel model for pyro-electro-catalytic hydrogen production in pure water
Authors: Schlechtweg Julian , Raufeisen Sascha , Stelter Michael , Braeutigam Patrick
Published: September 2019

The pyro-electro-catalytic induced generation of hydrogen gas is an environmentally friendly and sustainable way to convert excess thermal energy into a storable form.
Interfacial anomaly in low global warming potential refrigerant blends as predicted by molecular dynamics simulations
Authors: Li Yuting , Fouad Wael A. , Vega Lourdes F.
Published: September 2019

Anomalous behavior of the interfacial properties of low GWP refrigerants predicted by MD simulations.
The ground state of KO revisited: the millimeter and submillimeter spectrum of potassium oxide
Authors: Burton Mark A. , Russ Benjamin T. , Bucchino Matthew P. , Sheridan Phillip M. , Ziurys Lucy M.
Published: September 2019

Measurement of the millimeter-wave spectrum of the KO radical, using direct absorption methods, suggests that the ground electronic state is X2Πi with a close-lying excited state approximately 120 cm−1 higher in energy.
Understanding of binding energy calibration in XPS of lanthanum oxide by in situ treatment
Authors: Li Jerry Pui Ho , Zhou Xiaohong , Pang Yaoqi , Zhu Liang , Vovk Evgeny I. , Cong Linna , van Bavel Alexander P. , Li Shenggang , Yang Yong
Published: September 2019

La compounds photoelectron spectra calibration using La 4d5/2 peak as internal standard is proposed. This is demonstrated by characterizing different La compounds formed after in situ treatments on a nanorod La2O3 catalyst.
Readily recyclable carbon fiber reinforced composites based on degradable thermosets: a review
Authors: Wang Binbo , Ma Songqi , Yan Shifeng , Zhu Jin
Published: September 2019

CFRPs based on degradable thermosets have benefits of low energy consumption and reduced damage to carbon fibers during the recycling process.
Structural modification of zolpidem led to potent antimicrobial activity in imidazo[1,2-a]pyridine/pyrimidine-1,2,3-triazoles
Authors: Reddyrajula Rajkumar , Dalimba Udaya Kumar
Published: September 2019

New imidazo[1,2-a]pyridine/pyrimidine-1,2,3-triazoles (IPTs) designed by specific structural modifications of zolpidem exhibited superior antitubercular activity than the parent compound.
Towards the surface hydroxyl species in CeO2 nanoparticles
Authors: Plakhova Tatiana V. , Romanchuk Anna Yu. , Butorin Sergei M. , Konyukhova Anastasia D. , Egorov Alexander V. , Shiryaev Andrey A. , Baranchikov Alexander E. , Dorovatovskii Pavel V. , Huthwelker Thomas , Gerber Evgeny , Bauters Stephen , Sozarukova Madina M. , Scheinost Andreas C. , Ivanov Vladimir K. , Kalmykov Stepan N. , Kvashnina Kristina O.
Published: September 2019

X-ray absorption experiments at Ce L3 and M5 edges and theoretical calculations demonstrate that in addition to the nanoceria charge stability, the formation of hydroxyl groups at the surface affects the chemical performance of nanomaterials.
Structure, optical simulation and thermal stability of the HfB2-based high-temperature solar selective absorbing coatings
Authors: Qiu Xiao-Li , Gao Xiang-Hu , He Cheng-Yu , Chen Bao-Hui , Liu Gang
Published: September 2019

Transition metal borides are a kind of potential materials for high-temperature solar thermal applications.
Synthesis of Bi2WO6/Na-bentonite composites for photocatalytic oxidation of arsenic(iii) under simulated sunlight
Authors: Yang Quancheng , Dai Yunxiang , Huang Zijian , Zhang Jing , Zeng Ming , Shi Changsheng
Published: September 2019

Novel Bi2WO6/bentonite (denoted as BWO/BENT) composites were prepared via a typical hydrothermal process and employed for the photocatalytic oxidation of arsenic(iii) (As(iii)).
The oxygen reduction reaction catalyzed by Synechocystis sp. PCC 6803 flavodiiron proteins
Authors: Brown Katherine A. , Guo Zhanjun , Tokmina-Lukaszewska Monika , Scott Liam W. , Lubner Carolyn E. , Smolinski Sharon , Mulder David W. , Bothner Brian , King Paul W.
Published: September 2019

Photosynthetic flavodiiron proteins catalyze oxygen reduction at non-heme iron sites (brown spheres) using flavin (FMN) mediated electron transfer (black arrows).
Switching charge kinetics from type-I to Z-scheme for g-C3N4 and ZnIn2S4 by defective engineering for efficient and durable hydrogen evolution
Authors: Wang Mingya , Huang Shushu , Pang Xin , Song Meiting , Du Chunfang , Su Yiguo
Published: September 2019

A direct Z-scheme DC-g-C3N4/ZnIn2S4 heterostructure was obtained by regulating the defective and crystalline features of g-C3N4 to show robust hydrogen production performance.
Highly crystalline sodium manganese ferrocyanide microcubes for advanced sodium ion battery cathodes
Authors: Peng Fangwei , Yu Lei , Gao Pengyue , Liao Xiao-Zhen , Wen Jianguo , He Yu-shi , Tan Guoqiang , Ren Yang , Ma Zi-Feng
Published: September 2019

Highly crystalline Na1.92Mn[Fe(CN)6]0.98 microcubes with superior performance for advanced sodium ion battery cathodes were prepared using EDTA–MnNa2 as the precursor.
Fluorometric and colorimetric analysis of alkaline phosphatase activity based on a nucleotide coordinated copper ion mimicking polyphenol oxidase
Authors: Huang Hui , Bai Juan , Li Jiao , Lei Lulu , Zhang Wenjing , Yan Shujun , Li Yongxin
Published: September 2019

We have established a fluorometric and colorimetric detection method for alkaline phosphatase based on the difference in the catalytic activity of polyphenol oxidase mimetic enzymes formed by a nucleotide coordinated copper ion.
B–N coordinated triaryl pyrazole: effect of dimerization, and optical and NLO properties
Authors: Mukundam Vanga , Sa Shreenibasa , Kumari Anupa , Das Ritwick , Venkatasubbaiah Krishnan
Published: September 2019

Triaryl pyrazole B–N coordinate dimers with and without π-conjugation exhibit unique photophysical (linear as well as nonlinear optical) properties.
A candidate activation pathway for coagulation factor VII
Authors: Misenheimer Tina M. , Kumfer Kraig T. , Bates Barbara E. , Nettesheim Emily R. , Schwartz Bradford S.
Published: September 2019

The mechanism of generation of factor VIIa, considered the initiating protease in the tissue factor-initiated extrinsic limb of blood coagulation, is obscure. Decreased levels of plasma VIIa in individuals with congenital factor IX deficiency suggest that generation of VIIa is dependent on an activation product of factor IX. Factor VIIa activates IX to IXa by a two-step removal of the activation peptide with cleavages occurring after R191 and R226. Factor IXaα, however, is IX cleaved only after R226, and not after R191. We tested the hypothesis that IXaα activates VII with mutant IX that could be cleaved only at R226 and thus generate only IXaα upon activation. Factor IXaα demonstrated 1.6% the coagulant activity of IXa in a contact activation-based assay of the intrinsic activation limb and was less efficient than IXa at activating factor X in the presence of factor VIIIa. However, IXaα and IXa had indistinguishable amidolytic activity, and, strikingly, both catalyzed the cleavage required to convert VII to VIIa with indistinguishable kinetic parameters that were augmented by phospholipids, but not by factor VIIIa or tissue factor. We propose that IXa and IXaα participate in a pathway of reciprocal activation of VII and IX that does not require a protein cofactor. Since both VIIa and activated IX are equally plausible as the initiating protease for the extrinsic limb of blood coagulation, it might be appropriate to illustrate this key step of hemostasis as currently being unknown.
Leonurus cardiaca L., das Echte Herzgespann
Authors: Zhang Xinting , Melzig Matthias F
Published: September 2019

Leonurus cardiaca L. ist eine seit Langem genutzte europäische traditionelle Heilpflanze, die v. a. Terpene, Flavonoide, Stachydrin und das Pseudoalkaloid Leonurin enthält. Zubereitungen aus der Arzneidroge besitzen sedative, blutdrucksenkende, antioxidative bzw. entzündungshemmende Wirkungen. Ein therapeutischer Einsatz im Rahmen einer traditionellen Anwendung erfolgt bei nervösen Herzbeschwerden, Schilddrüsenüberfunktion und klimakterischen Beschwerden. Zurzeit gibt es nur unzureichende klinische Studien, und die den Wirkungen zugrundeliegenden Mechanismen sind noch nicht vollständig geklärt.
Zu den molekularbiologischen Grundlagen der antientzündlichen Wirkungen von Thymiankrautextrakt, Thymus vulgaris L. und Thymus zygis L., herba
Authors: Appel Kurt , Rose Thorsten , Collado Rojas Juan Antonio , Washausen Ute
Published: September 2019

ZUsammenfassung

Bereits früher publizierte Daten zeigten günstige Effekte von Thymian bei entzündlichen Prozessen. Um diese Erkenntnisse zu vertiefen, wurde in verschiedenen experimentellen Modellen ein Thymianextrakt auf die hier zugrundeliegenden molekularbiologischen Mechanismen in vitro untersucht. Nachgewiesen wurde eine Hemmung der LPS-induzierten Zytokin-Freisetzung von IL-1β, PGE2 sowie TNF-α in humanen Monozyten, eine Hemmung der LPS-induzierten Phosphorylierung und eine Aktivierung von IκBα sowie eine Inhibition der Transkriptionsaktivität von NF-κB und AP-1 in der Bronchialepithel-Zelllinie A549. Ein weiterer interessanter Befund war eine antagonistische Aktivität des untersuchten Thymianextraktes am TRPA1-Rezeptor, ein Rezeptor, der Hustenreize vermitteln kann. Die Anwendung des Thymianextraktes bei Erkältungs- bzw. Bronchitis-bedingtem Husten, bei dem entzündliche Prozesse auf bzw. in der Schleimhaut involviert sind, darf daher als plausibel gelten.
Kalzium, Magnesium und Phosphat
Authors: Ketteler Markus
Published: September 2019

Während die Hyperkalzämie in allen Stadien der Niereninsuffizienz inkl. des Dialysestadiums als bedenklich eingeschätzt wird, werden milde und asymptomatische Hypokalzämien als zumeist tolerabel betrachtet, insbesondere wenn sie im Kontext einer Calcimimetika-Therapie auftreten. Hypomagnesiämien sind bei Dialysepatienten mit erhöhtem Mortalitäts- und Frakturrisiko assoziiert – eindeutige Empfehlungen zu Magnesium-Zielbereichen bzw. zur Dosierung von Supplementationen lassen sich allerdings auf dem Boden der derzeitigen Datenlage noch nicht machen. Die Hyperphosphatämie als Mortalitätsrisikofaktor bei Dialysepatienten wird durch weitere aktuelle Studien bestätigt – interessanterweise existieren nun erste Hinweise, dass eine hohe Phosphat-Zufuhr auch eine Hypertonieentwicklung begünstigen kann.
Nierentransplantation
Authors: Wiederhold Dietmar
Published: September 2019

Lebendnierenspenden werden häufig durchgeführt, um den zunehmenden Bedarf nach einer Nierentransplantation realisieren zu können. Die Sorge um die Gesundheit des Empfängers kann den Entscheidungsprozess beeinflussen. Ebenso kann sich das Ergebnis der Transplantation auf das Leben und die Gesundheit des Spenders auswirken. Aus Sicht der Lebendspender sind die Langzeiterfahrungen allerdings bisher unzureichend erforscht. Daher war es das Ziel der Studie aus Norwegen, die langfristigen Erfahrungen von Spendern zu untersuchen.
Body Adiposity and Endocrine Profile of Female Wistar Rats of
Distinct Ages that were Early Weaned
Authors: Pietrobon Carla Bruna , Bertasso Iala Milene , Silva Beatrix S. , Peixoto-Silva Nayara , Oliveira Elaine , Moura Egberto Gaspar , Lisboa Patricia Cristina
Published: September 2019

Early weaning (EW) is a risk factor for metabolic syndrome. Male rats that were
precociously weaned present neonatal malnutrition and, in adulthood, developed
overweight, accumulation of body fat, dyslipidemia, changes in glycemic
homeostasis, hyperleptinemia, and increase of vitamin D. As metabolic profile of
early-weaned females is not known, we investigated the endocrine-metabolic
parameters in adolescence and adult female rats of 2 different EW models. Wistar
lactating rats and pups from both sexes were separated into 3 groups:
non-pharmacological EW (NPEW), dams were involved with a bandage interrupting
suckling in the last 3 days of lactation; pharmacological EW (PEW), dams were
bromocriptine-treated (0.5 mg/twice a day via intraperitoneal
injection) for 3 days before weaning; and control, dams whose pups ate milk
throughout lactation. At 21 days-old, NPEW and PEW females had lower body
weight. At 180 days-old, NPEW and PEW females showed higher feed efficiency,
weight gain, body fat percentage, and greater accumulation of gonadal and
retroperitoneal fat depots associated with adipocyte hypertrophy. NPEW females
also showed hyperphagia. Only NPEW females presented hyperleptinemia. Plasma
thyroid hormones and vitamin D were unchanged among EW females. Regarding sex
hormones, at 45 days-old, no change was found in EW females, while at 180
days-old, PEW females had hypoestrogenemia. EW increases the risk for obesity in
female rats in adulthood, as already demonstrated for males, although through
distinct mechanisms involving some hormones.
Operative Zugangswege beim Gleithoden und tiefen Leistenhoden – skrotaler Zugang
Authors: Younsi Nina Friederike , Zahn Katrin , Stein Raimund
Published: September 2019

Der Hodenhochstand ist die häufigste urogenitale Erkrankung im Kindesalter. Weiterhin gilt der inguinale Zugangsweg für die Orchidofunikolyse als operative Methode der Wahl. Eine Vielzahl von Studien konnten in den letzten zwei Jahrzehnten zeigen, dass die skrotale Orchidofunikolyse aufgrund der geringen Invasivität und einer damit verbundenen reduzierten Morbidität bei deutlich kürzerer Operationszeit und einem guten kosmetischen Ergebnis bei gleichem operativen Behandlungsergebnis eine gute Alternative beim Gleit- und tiefen Leistenhoden darstellt.
Hyper- und Hypokaliämien
Authors: Alscher Mark Dominik
Published: September 2019

Die Konzentration von Kalium im Serum resultiert aus dem Zusammenspiel von Kaliumaufnahme, -ausscheidung und interner Verteilung zwischen zellulären und extrazellulären Räumen und kann leicht bestimmt werden. Erhöhungen oder Erniedrigungen des Kalium-Wertes sind häufig. Insgesamt nehmen Patienten mit chronischen Nieren- und/oder Herzerkrankungen zu und diese erhalten häufig eine Diuretika-Therapie. Oft haben diese Patienten auch eine Nierenschädigung. Im ersten Fall finden sich häufig Hypokaliämien, im letzteren Fall Hyperkaliämien. Beides kann zu einer erhöhten Sterblichkeit führen. Deshalb sind das Erkennen und Behandeln dieser Störungen wichtig.
Störungen des Natrium-Haushaltes
Authors: Bonmann Tobias , Schricker Severin
Published: September 2019

Störungen des Natrium-Haushaltes gehören zu den häufigsten Elektrolytstörungen. Die Ausprägung der Störung und der damit einhergehenden Klinik kann stark variieren und ist v. a. von der Schnelligkeit des Auftretens der Elektrolytverschiebung abhängig. Pathologische Veränderungen des Natrium-Haushaltes sind mit einer erhöhten Mortalität assoziiert. Da die Ursachen sehr vielfältig sein können, ist die richtige Diagnosestellung nicht trivial und erfordert eine sorgfältige Interpretation von klinischen und laborchemischen Befunden. Ziel dieses Artikels ist daher, neben einer Wiederholung der Grundlagen des Natrium- und Wasser-Haushaltes die Ursachen, Diagnose und Therapie der Störungen des Natrium-Haushaltes verständlich zu machen.
Outcome nach Nierentransplantation
Authors: Latus Jörg , Kroll Katharina
Published: September 2019

Obwohl die präemptive Nierentransplantation mit einem besseren Patienten- und Organüberleben einhergeht, sind 83 % aller Patienten, die im Verlauf eine Nierentransplantation erhalten, zuvor dialysepflichtig 1. Der überwiegende Teil der Patienten entscheidet sich für die Durchführung der Hämodialyse: Hämodialyse (HD) vs. Peritonealdialyse (PD): 90 % vs. 10 % 2.
Autoantikörperdiagnostik bei rheumatischen Erkrankungen
Authors: Mahrhold Juliane , Csernok Elena
Published: September 2019

Die Labordiagnostik in der Rheumatologie ist neben den Routinelaboruntersuchungen mit Bestimmung der Entzündungsparameter, sowie hämatologischen und klinisch-chemischen Untersuchungen insbesondere durch den Nachweis spezifischer Autoantikörper definiert. Hierfür steht eine Vielzahl an Antikörpertests zur Verfügung: Für die rheumatoide Arthritis ergänzen Antikörper gegen cyclische citrullinierte Peptide zusätzlich zum Rheumafaktor die Diagnostik; der Nachweis von Antinukleäre Antikörpern (ANA) und die darauffolgenden antigenspezifischen Immunoassays werden für Kollagenosen, die Bestimmung der Anti-Neutrophile Cytoplasmatischen Antikörper (ANCA) zur Sub-Spezifizierung von Kleingefäßvaskulitiden genutzt. Im vorliegenden Beitrag soll eine Übersicht über die Antikörperdiagnostik in der Rheumatologie gegeben werden.
The Pathogenesis of Primary Biliary Cholangitis: A Comprehensive Review
Authors: Lleo Ana , Leung Patrick S.C. , Hirschfield Gideon M. , Gershwin Eric M.
Published: September 2019

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease characterized by autoimmune destruction of small to medium size intrahepatic bile ducts. The etiology of PBC remains unknown and pathogenesis features immune-mediated biliary injury, alongside the consequences of chronic cholestasis. PBC is strongly associated with the loss of immune tolerance against mitochondrial antigens and the subsequent presence of an articulated immunologic response that involves both humoral and cellular responses. Both environmental factors and genetic variants increase PBC susceptibility. Biliary epithelial cells have often been considered a passive target of the immune attack in PBC; however, cholangiocyte dedifferentiation, senescence, stress, and deoxyribonucleic acid damage have been recognized to play an active role in the pathogenesis of PBC. This review highlights and discusses the most relevant pathogenetic mechanisms in PBC, focusing on the key factors that lead to the onset of cholestasis and immune activation.
Microstructural control of the transport properties of β-FeSe films grown by sputtering
Authors: Ale Crivillero M. V. , Amigó M. L. , Haberkorn N. , Nieva G. , Guimpel J.
Published: September 2019

We have investigated the correlation between structural and transport properties in sputtered β-FeSe films grown onto SrTiO3 (100). The growth parameters, such as substrate temperature and thickness, have been varied in order to explore different regimes. In the limit of textured thick films, we found promising features like an enhanced Tc∼12 K, a relatively high Hc2, and a low anisotropy. By performing magnetoresistance and Hall coefficient measurements, we investigate the influence of the disorder associated with the textured morphology on some features attributed to subtle details of the multiband electronic structure of β-FeSe. Regarding the superconductor-insulator transition induced by reducing the thickness, we found a nontrivial evolution of the structural properties and morphology associated with a strained initial growth and the coalescence of grains. Finally, we discuss the origin of the insulating behavior in high-quality stressed epitaxial thin films. We found that a lattice distortion, described by Poisson’s coefficient associated with the lattice parameters a and c, may play a key role.
Clear-sky direct normal irradiance estimation based on adjustable inputs and error correction
Authors: Zhu Tingting , Xie Liping , Wei HaiKun , Wang Hai , Zhao Xin , Zhang Kanjian
Published: September 2019

The accurate estimation of direct normal irradiance (DNI) under clear sky conditions plays an important role in the concentrated solar thermal plant. A hybrid model with adjustable inputs is proposed to calculate the clear-sky DNI, including a base clear-sky model and an error-correction model. The base clear-sky model is able to estimate the clear-sky DNI at any place with only the local date and location information, and the error-correction model serves as a supplementary to improve the calculating accuracy with available meteorological data. The error-correction model effectively integrates a linear part and a nonlinear part, and its inputs are adjustable according to the available meteorological observations. Several experiments have been conducted to evaluate the performance of the proposed model with data from three observation stations provided by the National Renewable Energy Laboratory open database. The results show that the hybrid model is able to provide great improvement over the base clear-sky model with 28%–70% on normalized root mean square error, and it also performs better than those using a linear or nonlinear error correction model. It is concluded that the performance of the hybrid model is comparable with other published methods in calculating the clear-sky DNI with concrete statistics.
On-chip tunable photonic delay line
Authors: Ji Xingchen , Yao Xinwen , Gan Yu , Mohanty Aseema , Tadayon Mohammad A. , Hendon Christine P. , Lipson Michal
Published: September 2019

An on-chip tunable photonic delay line is a key building block for applications including sensing, imaging, and optical communication. However, achieving long and tunable delay lines within a small footprint remains challenging. Here, we demonstrate an on-chip tunable photonic delay line using ultralow loss high confinement Si3N4 waveguides with integrated microheaters. As an example of potential application, we embed a 0.4 m delay line within an optical coherence tomography (OCT) system. We show that the delay line can extend the OCT imaging range by 0.6 mm while maintaining a high signal to noise ratio. Our tunable photonic delay line is achieved without any moving parts which could provide high stability, critical for interference based applications.
Second harmonic microscopy of poled x-cut thin film lithium niobate: Understanding the contrast mechanism
Authors: Rüsing M. , Zhao J. , Mookherjea S.
Published: September 2019

Thin film lithium niobate has been of great interest recently, and an understanding of periodically poled thin films is crucial for both fundamental physics and device developments. Second-harmonic (SH) microscopy allows for the noninvasive visualization and analysis of ferroelectric domain structures and walls. While the technique is well understood in bulk lithium niobate, SH microscopy in thin films is largely influenced by interfacial reflections and resonant enhancements, which depend on film thicknesses and substrate materials. We present a comprehensive analysis of SH microscopy in x-cut lithium niobate thin films, based on a full three-dimensional focus calculation and accounting for interface reflections. We show that the dominant signal in backreflection originates from a copropagating phase-matched process observed through reflections, rather than direct detection of the counterpropagating signal as in bulk samples. We simulate the SH signatures of domain structures by a simple model of the domain wall as an extensionless transition from a −χ(2) to a +χ(2) region. This allows us to explain the main observation of domain structures in the thin-film geometry, and, in particular, we show that the SH signal from thin poled films allows to unambiguously distinguish areas, which are completely or only partly inverted in depth.
Experimental validation of interpolation method for pair correlations in model crystals
Authors: Yakovlev Egor V. , Chaudhuri Manis , Kryuchkov Nikita P. , Ovcharov Pavel V. , Sapelkin Andrei V. , Yurchenko Stanislav O.
Published: September 2019

Accurate analysis of pair correlations in condensed matter allows us to establish relations between structures and thermodynamic properties and, thus, is of high importance for a wide range of systems, from solids to colloidal suspensions. Recently, the interpolation method (IM) that describes satisfactorily the shape of pair correlation peaks at short and at long distances has been elaborated theoretically and using molecular dynamics simulations, but it has not been verified experimentally as yet. Here, we test the IM by particle-resolved studies with colloidal suspensions and with complex (dusty) plasmas and demonstrate that, owing to its high accuracy, the IM can be used to experimentally measure parameters that describe interaction between particles in these systems. We used three- and two-dimensional colloidal crystals and monolayer complex (dusty) plasma crystals to explore suitability of the IM in systems with soft to hard-sphere-like repulsion between particles. In addition to the systems with pairwise interactions, if many-body interactions can be mapped to the pairwise ones with some effective (e.g., density-dependent) parameters, the IM could be used to obtain these parameters. The results reliably show that the IM can be effectively used for analysis of pair correlations and interactions in a wide variety of systems and therefore is of broad interest in condensed matter, complex plasma, chemical physics, physical chemistry, materials science, and soft matter.
Three-dimensional flow simulations for polymer extrudate swell out of slit dies from low to high aspect ratios
Authors: Tang Dahang , Marchesini Flavio H. , Cardon Ludwig , D’hooge Dagmar R.
Published: September 2019

The impact of the slit die geometry and the polymer melt flow characteristics on the extrudate swell behavior, which is a key extrusion operating parameter, is highlighted. Three-dimensional (3D) numerical simulations based on the finite element method are compared with their conventional two-dimensional (2D) counterparts at the same apparent shear rates using ANSYS Polyflow software. The rheological behavior is described by the differential multimode Phan-Thien-Tanner constitutive model, with polypropylene as a reference. It is shown that increasing the aspect ratio of the die geometry (width/height ratio variation from 1 to 20) contributes to a significant change in the 3D extrudate deformation (relative changes of 10% in several directions; absolute changes up to 30%) and delays the equilibrium axial position (up to a factor 10). High aspect ratios induce a switch to contract flow (swell ratio <1) for the edge height swell. The 3D extrudate swell strongly deviates from the 2D simplified case due to the die effect near the wall, even for higher aspect ratios. Also a different relation with the material parameters is recorded. The initially large swell behavior is followed by a small shrinkage flow in the middle height direction which cannot be captured by the 2D counterpart. The findings are supported by a comprehensive analysis of the velocity and stress fields in and out of the slit dies.
Radiation transport and scaling of optical depth in Nd:YAG laser-produced microdroplet-tin plasma
Authors: Schupp R. , Torretti F. , Meijer R. A. , Bayraktar M. , Sheil J. , Scheers J. , Kurilovich D. , Bayerle A. , Schafgans A. A. , Purvis M. , Eikema K. S. E. , Witte S. , Ubachs W. , Hoekstra R. , Versolato O. O.
Published: September 2019

Experimental scaling relations of the optical depth are presented for the emission spectra of a tin-droplet-based, 1-μm-laser-produced plasma source of extreme-ultraviolet (EUV) light. The observed changes in the complex spectral emission of the plasma over a wide range of droplet diameters (16–65 μm) and laser pulse durations (5–25 ns) are accurately captured in a scaling relation featuring the optical depth of the plasma as a single, pertinent parameter. The scans were performed at a constant laser intensity of 1.4 × 1011 W/cm2, which maximizes the emission in a 2% bandwidth around 13.5 nm relative to the total spectral energy, the bandwidth relevant for industrial EUV lithography. Using a one-dimensional radiation transport model, the relative optical depth of the plasma is found to linearly increase with the droplet size with a slope that increases with the laser pulse duration. For small droplets and short laser pulses, the fraction of light emitted in the 2% bandwidth around 13.5 nm relative to the total spectral energy is shown to reach high values of more than 14%, which may enable conversion efficiencies of Nd:YAG laser light into—industrially—useful EUV radiation rivaling those of current state-of-the-art CO2-laser-driven sources.
Dissipative particle dynamics with reactions: Application to RDX decomposition
Authors: Lísal Martin , Larentzos James P. , Sellers Michael S. , Schweigert Igor V. , Brennan John K.
Published: September 2019

We present a general, flexible framework for a constant-energy variant of the dissipative particle dynamics method that allows chemical reactions (DPD-RX). In our DPD-RX approach, reaction progress variables are assigned to each particle that monitor the time evolution of an extent-of-reaction associated with the prescribed reaction mechanisms and kinetics assumed to occur within the particle, where chemistry can be modeled using complex or reduced reaction mechanisms. We demonstrate our DPD-RX method by considering thermally initiated unimolecular decomposition of the energetic material, cyclotrimethylene trinitramine (RDX), into a molecular gas mixture. Studies are performed to demonstrate the effect of a spatially averaged particle internal temperature and a local reaction volume term in the chemical kinetics expressions, where both provide implicit mechanisms for capturing condensed phase reactivity. We also present an analysis of the expansion of the product gas mixture during decomposition. Finally, a discussion of other potential applications and extensions of the DPD-RX method is given.
Random two-frame phase-shifting interferometry via minimization of coefficient of variation
Authors: Cheng Zhongtao , Liu Dong , Zhang Lei
Published: September 2019

Random two-frame phase-shifting interferometry (PSI) is an advanced technique to retrieve the phase information from as few as two interferograms with unknown phase steps. Because of the advantages of no requirement for accurate phase shifters and much less time for data acquisition and processing, random two-frame PSI is attracting more and more interest in fast and high-precision optical metrology. However, reconstructing the phase from only two interferograms is challenging because it is an ill-posed problem in essence, especially when the phase step is unknown. Although some solutions have been proposed for this problem to date, most of them require complicated preprocessing or special usage preconditions for interferograms to be demodulated. In this letter, we developed an elegant phase reconstruction method for random two-frame PSI, which is much different from frameworks of existing methods. In the proposed approach, the phase of random two-frame PSI can be accurately reconstructed using the phase step value which minimizes the coefficient of variation (CV) of the modulation term of interferograms. Sufficient numerical simulations and experimental data demonstrate the high accuracy and high efficiency of this CV minimization (CVM) method. Moreover, its performance is not limited by the number of fringes in interferograms, in contrast to existing state-of-the-art approaches. We anticipate extensive applications of the CVM method in random two-frame PSI in the future.
Magnetostriction in magnetic gels and elastomers as a function of the internal structure and particle distribution
Authors: Fischer Lukas , Menzel Andreas M.
Published: September 2019

Magnetic gels and elastomers are promising candidates to construct reversibly excitable soft actuators, triggered from outside by magnetic fields. These magnetic fields induce or alter the magnetic interactions between discrete rigid particles embedded in a soft elastic polymeric matrix, leading to overall deformations. It is a major challenge in theory to correctly predict from the discrete particle configuration the type of deformation resulting for a finite-sized system. Considering an elastic sphere, we here present such an approach. The method is in principle exact, at least within the framework of linear elasticity theory and for large enough interparticle distances. Different particle arrangements are considered. We find, for instance, that regular simple cubic configurations show elongation of the sphere along the magnetization if oriented along a face or space diagonal of the cubic unit cell. Contrariwise, with the magnetization along the edge of the cubic unit cell, they contract. The opposite is true in this geometry for body- and face-centered configurations. Remarkably, for the latter configurations but the magnetization along a face or space diagonal of the unit cell, contraction was observed to revert to expansion with decreasing Poisson ratio of the elastic material. Randomized configurations were considered as well. They show a tendency of elongating the sphere along the magnetization, which is more pronounced for compressible systems. Our results can be tested against actual experiments for spherical samples. Moreover, our approach shall support the search of optimal particle distributions for a maximized effect of actuation.
Time resolved mechanism of the isotope selectivity in the ultrafast light induced dissociation in N2
Authors: Komarova Ksenia G. , Remacle Francoise , Levine R. D.
Published: September 2019

The time evolution of a vacuum ultraviolet excited N2 molecule is followed all the way from an ultrafast excitation to dissociation by a quantum mechanical simulation. The primary aim is to discern the role of the excitation by a pulse short compared to the vibrational period, to discern the different coupling mechanisms between different electronic states, nonadiabatic, spin orbit, and to analyze the origin of any isotopic effect. We compare the picture in the time and energy domains. The initial ultrafast excitation pumps the molecule to a coherent electronic wave packet to which several singlet bound electronic states contribute. The total nonstationary wave function is given as a coherent sum of nuclear wave packets on each electronic state times the stationary electronic wave function. When the wave packets on different electronic states overlap, they are coupled in a mass-dependent manner whether one uses an adiabatic or a diabatic electronic basis. A weak spin-orbit coupling acts as a bottleneck between the bound singlet part of phase space and the triplet manifold of states in which dissociation takes place. To describe the spin-orbit perturbation that is ongoing in time, an energy-resolved eigenstate representation appears to be more intuitive. In the eigenstate basis, the singlet-to-triplet population transfer is large only between those vibronic eigenstates that are quasiresonant in energy. The states in resonance are different for different excitation energy ranges. The resonances are mass dependent, which explains the control of the isotope effect through the profile of the pulse.
Water hydrogen-bonding structure and dynamics near lipid multibilayer surface: Molecular dynamics simulation study with direct experimental comparison
Authors: Lee Euihyun , Kundu Achintya , Jeon Jonggu , Cho Minhaeng
Published: September 2019

Lipid multibilayers are excellent model systems for studying water structures and dynamics near biological membrane surfaces. In particular, the orientational distribution and rotational dynamics of water molecules near hydrophilic lipid groups are found to be sensitive to the chemical nature and charge distributions of the amphiphilic lipids. To elucidate how different parts of these lipids affect the water hydrogen-bonding structure and dynamics and to directly compare with recent experimental results, we carried out molecular dynamics (MD) simulations of lipid multibilayer systems. We found that the water molecules close to positively charged choline groups have a broad distribution of orientations due to the clathratelike shell formation around the choline groups but that those associated with phosphate groups, even in the second hydration shell, are orientationally restricted due to their strong hydrogen bonding with the phosphate group. These MD simulation results are in excellent agreement with our time-resolved infrared pump-probe anisotropy measurements, and we believe that they provide valuable insights into the role of water molecules in maintaining lipid bilayer integrity.
Localised plasmons in sphere-like fullerenes and nanoparticles with conducting shells: Classical electrodynamic approach
Authors: Davidovich M.V.
Published: September 2019

Based on the classical electrodynamic approach, we consider localised plasmons in fullerenes and small particles with metal layers and shells. At low energies of the radiation quantum, models of fullerenes as conducting shells are used taking into account the contribution of only π electrons, and at high energies, of both π and σ electrons. The obtained maxima of the scattering cross sections correspond to the values of 20 and 27 eV that were determined experimentally and in quantum models for the maxima of the photoionisation cross sections of fullerenes C60 and C28, respectively. Approximate analytical results are presented for resonant frequencies, Q factors, radiation patterns, scattering and absorption cross sections for sphere-like particles and fullerenes, as well as integral equations and functionals for dielectric particles with a conducting shell of arbitrary shape. Analysis relies on the use of effective surface conductivity.
Recording of pulsed currents by a fibre-optic Faraday effect-based sensor with limited frequency band
Authors: Gubin V.P. , Starostin N.I. , Przhiyalkovsky Ya.V. , Morshnev S.K. , Sazonov A.I.
Published: September 2019

We have studied, experimentally and theoretically, the dependence of the amplitude and noise response parameters of a fibre-optic Faraday effect-based current sensor on the photodetector frequency band in recording rectangular current pulses, the duration of which does not exceed the time of light propagation through the sensing fibre. The presence of an optimal band at which the signal-to-noise ratio has a pronounced maximum is demonstrated. It is shown that the optimal bandwidth is close in magnitude to the inverse time of light passage through the fibre. The revealed feature is explained by the difference in dependences of the response amplitude and the white noise level of optical radiation on the frequency band of the photodetector. A technique for amplitude error correction at the optimal band is proposed.
On exact determination of small radiation frequency shifts using a Fabry – Perot interferometer
Authors: Gordeev A.A. , Efimkov V.F. , Zubarev I.G. , Mikhailov S.I.
Published: September 2019

A method for the mathematical processing of digitised Fabry – Perot interferograms is proposed and implemented to eliminate subjective factors and increase the accuracy of measurements.
Versitile X-ray diagnostics of laser-produced high-temperature plasmas using an ultra-high luminosity spectrometer
Authors: Shevelko A.P.
Published: September 2019

Versitile diagnostics of high-temperature magnesium laser-produced plasmas is performed using an ultra-high luminosity X-ray focusing crystal spectrometer. The plasmas are produced by focusing nanosecond laser pulses (0.53 μm, 1 J, 2 ns) on a massive magnesium target. The absolute intensities and X-ray yields are measured for the resonance lines of H- and He-like ions (spectral range: Δλ = 8 –10 Å), the electron temperature of plasmas is determined (range: T
e = 200 – 550 eV), and the behaviour of these parameters is established in a broad range of laser pulse energy E
L (10 mJ – 1 J). This approach permits the parameters of laser-plasma radiation sources to be monitored in real time in a wide intensity range (difference in intensity: over 104) and in a broad range of plasma parameters.
Effect of recovery time of nonlinear absorber saturated losses on the soliton pulse structure in a fibre laser with different cavity lengths
Authors: Mastin A.A. , Ryabochkina P.A.
Published: September 2019

Using numerical simulation methods, we have calculated the dependences of the pulse profile and spectrum of a ring fibre laser in the region of anomalous group velocity dispersion on the length of the laser cavity and the recovery time of the nonlinear absorber saturated losses. It is found that with increasing cavity length the laser pulse acquires a pedestal, the positions of its edges corresponding to the frequencies of the Kelly sidebands. It is shown that the finiteness of the recovery time of the saturable absorber leads to an asymmetry in the profile and spectrum of the laser pulse.
High-coupling distributed feedback lasers for the 1.55 μm spectral region
Authors: Dudelev V.V. , Mikhailov D.A. , Chistyakov D.V. , Kognovitskaya E.A. , Lyutetskiy A.V. , Slipchenko S.O. , Pikhtin N.A. , Gladyshev A.G. , Denisov D.V. , Voropaev K.O. , Ionov A.S. , Babichev A.V. , Novikov I.I. , Karachinskii L.Ya. , Kuchinskii V.I. , Egorov A.Yu , Sokolovskii G.S.
Published: September 2019

A technique for the development of high-coupling distributed-feedback (DFB) lasers for the 1.55 μm spectral region is described. The lasers demonstrate stable single-frequency generation in a broad temperature range with a maximum side-mode suppression ratio of more than 30 dB.
Immobilisation of palladium nanostructures in polyethersulfone beads: recyclable catalyst for chromium(VI) remediation
Authors: Markad Uddhav S. , Naik Devidas B. , Singh Krishan Kant , Kumar Manmohan , Sharma Geeta K.
Published: September 2019

Environmental contextChromium, a carcinogenic metal present in the wastewater of several industries, is currently removed by treatment with large amounts of chemicals and expensive nano-catalysts. We have immobilised a nano-catalyst in tiny polymeric balls that are highly efficient at capturing chromium, and are easy to isolate for multiple reuse. Using our methodology, consumption of chemicals for removing chromium from wastewater is reduced by 97%.
AbstractWe have synthesised and immobilised palladium nanostructures in porous polyethersulfone beads for the first time and demonstrated their catalytic application for the reductive transformation of toxic CrVI to nontoxic CrIII by formic acid at 25°C. The reduction of CrVI using palladium-polyethersulfone composite beads (Pd-PES), with a minimal Pd loading of 0.4 wt%, is found to be 98% with excellent operational stability retained up to 100 consecutive reaction cycles. Pseudo-first-order rate constant kapp for the 1st and 100th catalytic cycles is 0.167 and 0.158min−1 respectively. Pd-PES beads having a diameter of 2mm are easy to isolate post reduction by simple mesh filtration and can be re-used consecutively without any treatment. Owing to the high catalytic stability of the Pd nanostructures inside the beads, and the good mechanical and thermal stability of polyethersulfone, these beads can withstand rigorous treatment like mechanical stirring and elevated temperature, which renders them as highly reusable and as promising metal-polymer composite for practical application in CrVI remediation. For large scale application of this catalyst, we have demonstrated a methodology which reduces the consumption of formic acid by 98% in chromium remediation technology.