bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding controls on the geochemistry of hydrocarbon produced waters from different basins across the US
Authors: Sharma Shikha , Agrawal Vikas , Akondi Rawlings N. , Wang Yifeng , Hakala Alexandra
Published: December 2020

Geochemistry of produced water (PW) from different conventional and unconventional formations with varying lithology, depositional environment, and hydrogeological history were analyzed to understand the major controls on PW quality.
Scutellarin protects mouse ovarian granulosa cells from injury induced by the toxin zearalenone
Authors: Yi Yanyan , Wan Shuangxiu , Wang Shaoyu , Khan Ajab , Guo Jianhua , Zheng Xiaozhong , Li Hongquan , Sun Na
Published: December 2020

This study investigated the protective effect of scutellarin on ZEA-induced reproductive toxicity both in vivo and in vitro and explored the underlying mechanisms.
Microfluidic organ-on-a-chip model of the outer blood–retinal barrier with clinically relevant read-outs for tissue permeability and vascular structure
Authors: Arık Yusuf B. , Buijsman Wesley , Loessberg-Zahl Joshua , Cuartas-Vélez Carlos , Veenstra Colin , Logtenberg Sander , Grobbink Anne M. , Bergveld Piet , Gagliardi Giuliana , den Hollander Anneke I. , Bosschaart Nienke , van den Berg Albert , Passier Robert , van der Meer Andries D.
Published: December 2020

This organ-on-a-chip device of the outer blood retinal barrier will allow future studies of complex disease mechanisms and treatments of visual disorders using clinically relevant endpoints in vitro.
Dramatic influence of the hydroxy functionality of azasugar moiety in the head group region of tocopherol-based cationic lipids on in vitro gene transfection efficacies
Authors: Muripiti Venkanna , Lohchania Brijesh , Ravula Venkatesh , Manturthi Shireesha , Marepally Srujan , Velidandi Amarnath , Patri Srilakshmi V.
Published: December 2020

Cationic lipids have been effectively used as nonviral vectors for the delivery of polynucleic acids into the cytosol.
Aza-heterocyclic frameworks through intramolecular π-system trapping of spiro-N-acyliminiums generated from isoindolinone
Authors: Chortani Sarra , Othman Mohamed , Lawson Ata Martin , Romdhane Anis , Ben Jannet Hichem , Knorr Michael , Brieger Lukas , Strohmann Carsten , Daïch Adam
Published: December 2020

Spiro-acetoxylactams, obtained easily by the tandem carbonyl reduction/O-acylation, were submitted to acids giving through π-cationic cyclization aza-heterocyclic systems including amino-acids.
Direct synthesis of highly porous interconnected carbon nanosheets from sodiumd-isoascorbic acid for the simultaneous determination of catechol and hydroquinone
Authors: Zheng Yin , Chen Jiabing , Lu Youluan , Song Xinjian , Shi Zhen
Published: December 2020

Interconnected porous carbon was prepared by pyrolyzing sodiumd-isoascorbic acid. An electrochemical sensor for simultaneous detection of hydroquinone and catechol was fabricated by modification with porous carbon on the glassy carbon electrode surface.
Biocatalytic ketone reductions using Biobeads for miniaturized high throughput experimentation
Authors: Chew Jia Shen , Ho Thi Thanh Nha , Lee Chi-Lik Ken
Published: December 2020

Miniaturized reactions conducted in parallel can lead to increased productivity in laboratories without depleting high value reagents.
A cage-based covalent organic framework for drug delivery
Authors: Li Ming , Peng Yu , Yan Fei , Li Chunguang , He Yiqiang , Lou Yue , Ma Dingxuan , Li Yi , Shi Zhan , Feng Shouhua
Published: December 2020

A novel cage-based crystalline covalent organic framework, i.e. Cage-COF-TT (TT = triammonia–terephthalaldehyde), was prepared from a prism-like triammonia-containing molecular cage and terephthalaldehyde.
High topological tri-metal phosphide of CoP@FeNiP toward enhanced activities in oxygen evolution reaction
Authors: Wang Jianzhi , Chen Chen , Cai Ning , Wang Miao , Li Hui , Yu Faquan
Published: December 2020

The development of non-precious metal electrocatalysts with high activity, good durability and low cost to replace precious metal electrocatalysts is highly demanded for oxygen evolution reaction (OER).
Antiferromagnetic proximity coupling between semiconductor quantum emitters in WSe2 and van der Waals ferromagnets
Authors: Liu Na , Gallaro Cosmo M. , Shayan Kamran , Mukherjee Arunabh , Kim Bumho , Hone James , Vamivakas Nick , Strauf Stefan
Published: December 2020

Quantum emitter magnetometry can probe interface magnetism in van der Waals ferromagnets. The hysteretic optical response demonstrates switching from ferromagnetic to antiferromagnetic proximity-coupling in the presence of surface oxides.
A 2D material-based floating gate device with linear synaptic weight update
Authors: Park Eunpyo , Kim Minkyung , Kim Tae Soo , Kim In Soo , Park Jongkil , Kim Jaewook , Jeong YeonJoo , Lee Suyoun , Kim Inho , Park Jong-Keuk , Kim Gyu Tae , Chang Jiwon , Kang Kibum , Kwak Joon Young
Published: December 2020

A three-terminal top-gated flash device based on two-dimensional materials with a high coupling ratio exhibits highly linear synaptic weight updates.
Recent advances in biofluid detection with micro/nanostructured bioelectronic devices
Authors: Li Hu , Gu Shaochun , Zhang Qianmin , Song Enming , Kuang Tairong , Chen Feng , Yu Xinge , Chang Lingqian
Published: December 2020

Micro/nanostructured bioelectronic devices for various biofluid detection applications are systematically summarized and discussed with new insights for future health monitoring.
IFPTML mapping of nanoparticle antibacterial activity vs. pathogen metabolic networks
Authors: Ortega-Tenezaca Bernabé , González-Díaz Humberto
Published: December 2020

Machine learning mapping of antibacterial nanoparticles vs. bacteria metabolic network structure.
Redox/photo dual-responsive, self-targeted, and photosensitizer-laden bismuth sulfide nanourchins for combination therapy in cancer
Authors: Poudel Kishwor , Banstola Asmita , Gautam Milan , Soe Zar Chi , Pham Le Minh , Jeong Jee-Heon , Choi Han-Gon , Ku Sae Kwang , Yong Chul Soon , Tran Tuan Hiep , Kim Jong Oh
Published: December 2020

Scheme of fabrication and action of NUs after tumor internalizationviafolate receptors, redox-triggered S–S bond cleavage, and laser-receptive behavior.
Mechanistic divergence between (4S,7R)-germacra-(1(10)E,5E)-dien-11-ol synthases from Dictyostelium purpureum and Streptomyces coelicolor
Authors: Xu Houchao , Rinkel Jan , Chen Xinlu , Köllner Tobias G. , Chen Feng , Dickschat Jeroen S.
Published: December 2020

The enzyme mechanism of germacradienol synthase DpTPS9 from Dictyostelium purpureum has been studied by labelling experiments and site-directed mutagenesis, and is different to the mechanism of geosmin synthase SCO6073 from Streptomyces coelicolor.
Novel tetraphenylethylene (TPE)-functionalized nitroxide/alkoxyamine for nitroxide-mediated homogeneous and heterogeneous polymerizations
Authors: Ma Huanhuan , Wang Linan , Liang Yachao , Cui Zhe , Fu Peng , Liu Minying , Qiao Xiaoguang , Pang Xinchang
Published: December 2020

Tetraphenylethylene (TPE)-functionalized nitroxide/alkoxyamine realized the “in situ observation” of the NMP process for both homogeneous and heterogeneous polymerization systems.
Stereoselective polymerization of rac-lactide catalyzed by zwitterionic calcium complexes
Authors: Liu Na , Liu Doudou , Liu Bo , Zhang Hao , Cui Dongmei
Published: December 2020

Two zwitterionic calcium complexes L1CaN(SiMe3)2(THF) (1) and L2CaN(SiMe3)2 (2) via protolysis reaction were synthesized. At −75 °C, 1 gave a heterotactic sequence enriched polylactide, whilst 2 produced an isotactic sequence enriched polymer.
Developing non-isocyanate urethane-methacrylate photo-monomers for 3D printing application
Authors: Singh Neelima , Bakhshi Hadi , Meyer Wolfdietrich
Published: December 2020

Synthesis of urethane-methacrylate photo-monomersviaa non-isocyanate route for 3D printing of flexible biomedical materials.
Seven confluence principles: a case study of standardized statistical analysis for 26 methods that assign net atomic charges in molecules
Authors: Manz Thomas A.
Published: December 2020

Standardized statistical analysis of many methods to assign net atomic charges revealed relative charge transfer magnitudes and confluent correlations.
Effect of the loading amount and arrangement of iodine chains on the interfacial thermal transport of carbon nanotubes: a molecular dynamics study
Authors: Zou Hanying , Feng Yanhui , Qiu Lin , Zhang Xinxin
Published: December 2020

Study of the heat transfer enhancement mechanism of a CNTs' interface by iodine particles loaded in different amounts and arrangements.
Assessment of the vigor of rice seeds by near-infrared hyperspectral imaging combined with transfer learning
Authors: Yang Yong , Chen Jianping , He Yong , Liu Feng , Feng Xuping , Zhang Jinnuo
Published: December 2020

Rice seed vigor plays a significant role in determining the quality and quantity of rice production.
Poly(trimethylene carbonate-co-valerolactone) copolymers are materials with tailorable properties: from soft to thermoplastic elastomers
Authors: Reinišová Lucie , Hermanová Soňa
Published: December 2020

Aliphatic poly(ester-carbonates) are receiving extensive research attention as tailorable materials suitable for multiple applications from tissue engineering and 3D scaffold printing to drug delivery.
Degradation of pesticides using amine-functionalized cellulose nanocrystals
Authors: Swasy Maria I. , Brummel Beau R. , Narangoda Chandima , Attia Mohamed F. , Hawk Joshua M. , Alexis Frank , Whitehead Daniel C.
Published: December 2020

A series of amine-functionalized cellulose nanocrystal materials were successfully synthesized, characterized, and evaluated for the remediation of pesticide contaminants from organic and aqueous media.
Photoelectrochemical enzymatic sensor for glucose based on Au@C/TiO2 nanorod arrays
Authors: Ge Lianyuan , Hou Rui , Cao Yang , Tu Jinchun , Wu Qiang
Published: December 2020

In this work, a photoelectrochemical (PEC) glucose biosensor was synthesized on the basis of a type of Au@C/TiO2 composite by using an unsophisticated secondary hydrothermal strategy.
Facile assembly of 1,5-diazocan-2-ones via cyclization of tethered sulfonamides to cyclopropenes
Authors: Matheny Jonathon P. , Yamanushkin Pavel M. , Petillo Peter A. , Rubin Michael
Published: December 2020

The sulfonamide moiety was evaluated as an activating and stabilizing functional group in the metal templated strain release-driven intramolecular nucleophilic addition of amines to cyclopropenes to generate 1,5-diazocan-2-ones.
Prescribed drugs containing nitrogen heterocycles: an overview
Authors: Heravi Majid M. , Zadsirjan Vahideh
Published: December 2020

In this review, we try to present a comprehensive overview on top prescribed drugs containing nitrogen heterocycles, describing their pharmacological properties, medical applications and their selected synthetic pathways.
Real-time imaging of surface chemical reactions by electrochemical photothermal reflectance microscopy
Authors: Zong Cheng , Zhang Chi , Lin Peng , Yin Jiaze , Bai Yeran , Lin Haonan , Ren Bin , Cheng Ji-Xin
Published: December 2020

The potential-dependent photothermal signal, which is sensitive to the free electron density, map the evolution of surface species on the electrode in real time.
Designing tubular conducting polymer actuators for wireless electropumping
Authors: Gupta Bhavana , Zhang Lin , Melvin Ambrose Ashwin , Goudeau Bertrand , Bouffier Laurent , Kuhn Alexander
Published: December 2020

Tubular conducting polymer actuators are used for developing a wireless electropumping device. Bipolar electrochemistry, allowing symmetry breaking in terms of polarization and electrochemical reactions, is the key ingredient for efficient pumping.
Towards photoswitchable quadruple hydrogen bonds via a reversible “photolocking” strategy for photocontrolled self-assembly
Authors: Wei Lu , Han Shi-Tao , Jin Ting-Ting , Zhan Tian-Guang , Liu Li-Juan , Cui Jiecheng , Zhang Kang-Da
Published: December 2020

A photolocking strategy is described to achieve the construction of effectively photoswitchable quadruple hydrogen bonds featuring with photoregulable H-bonding affinities, which is further applied in the photocontrollable H-bonded self-assemblies.
Enhanced voltammetric anion sensing at halogen and hydrogen bonding ferrocenyl SAMs
Authors: Hein Robert , Li Xiaoxiong , Beer Paul D. , Davis Jason J.
Published: December 2020

Surface enhancement effects in the sensing of anions at redox-active molecular films are investigated in detail and rationalised based on a consideration of the dielectric binding microenvironment.
Switch chemistry at cryogenic conditions: quantum tunnelling under electric fields
Authors: Kirshenboim Omer , Frenklah Alexander , Kozuch Sebastian
Published: December 2020

Adding an external electric field to reactions driven by quantum mechanical tunneling brings a whole new dimension to the idea of switch chemistry.
Controlling nanostructure and mechanical properties in triblock copolymer/monomer blends via reaction-induced phase transitions
Authors: Torres Vincent M. , LaNasa Jacob A. , Vogt Bryan D. , Hickey Robert J.
Published: December 2020

In situ polymer grafting from the mid-block of an ABA triblock copolymer leads to morphology transitions and enhanced mechanical properties.
Elastic constants of biological filamentous colloids: estimation and implications on nematic and cholesteric tactoid morphologies
Authors: Bagnani Massimo , Azzari Paride , De Michele Cristiano , Arcari Mario , Mezzenga Raffaele
Published: December 2020

Biological liquid crystals, such as cellulose and amyloid fibrils, show a physical behaviour difficult to predict and characterize. Here we present four different techniques to estimate the elastic constantK1,K2andK3for three different biological filamentous colloids.
Penetration and preferential binding of charged nanoparticles to mixed lipid monolayers: interplay of lipid packing and charge density
Authors: Chaudhury Anurag , Debnath Koushik , Bu Wei , Jana Nikhil R. , Basu Jaydeep Kumar
Published: December 2020

Designing of nanoparticles (NPs) for biomedical applications or mitigating their cytotoxic effects requires microscopic understanding of their interactions with cell membranes.
Molecular ordering and phase segregation induced by a volatile solid additive for highly efficient all-small-molecule organic solar cells
Authors: Chen Shanshan , Ye Junfeng , Yang Qianguang , Oh Jiyeon , Hu Dingqin , Yang Ke , Odunmbaku George Omololu , Li Feng , Yu Qingqing , Kan Zhipeng , Xiao Zeyun , Yang Changduk , Lu Shirong , Sun Kuan
Published: December 2020

The IC-IF volatile solid additive enables an interpenetrating BHJ microstructure with a predominant π-face-on molecular packing, affording an efficient all-small-molecule OSCs with an efficiency of 14.43% and an outstanding fill factor of 73.53%.
A general route towards two-dimensional organic crystal-based functional fibriform transistors for wearable electronic textiles
Authors: Zheng Lei , Wang Cong , Tian Xinzi , Zhang Xiaotao , Dong Huanli , Hu Wenping
Published: December 2020

High-performance fibriform OFET-based functional devices based on two-dimensional crystals of organic semiconductors are demonstrated through a novel jigsaw puzzle strategy.
Outage analysis and optimisation of NOMA‐based amplify‐and‐forward relay systems
Authors: Lv Guocheng , Li Xunan , Xue Ping , Jin Ye
Published: December 2020

In this study, a non‐orthogonal multiple access based cooperative relay system is investigated, where the source serves multiple destinations via an amplify‐and‐forward relay. Direct links between the source and destinations are considered to form a general framework while the maximum ratio combination (MRC) is applied to obtain the largest decoding signal‐to‐interference‐plus‐noise ratio (SINR). Firstly, the outage performance is analysed with given successive interference cancellation (SIC) order and power allocation. An excellent approximated expression for the exact outage probabilities is derived in closed form. In addition, the asymptotic expression at high signal‐to‐noise ratio is provided to gain further insights. Then, in order to fully exploit the potential of the system, a joint optimisation of SIC order design and power allocation is formulated, with the objective of minimising the maximum outage probability of all destinations. By exploring the inherent property of the system, an optimal solution of SIC order and power allocation is developed. Finally, simulation results are presented to verify the correctness of the analytical results as well as indicate the efficiency of authors' SIC order design and power allocation algorithm.
Parameter estimation of impulsive noise for channel coded communication systems
Authors: Chen Chun‐Yin , Chiu Mao‐Ching
Published: December 2020

In this paper, an impulsive noise estimation algorithm for generating bit log‐likelihood ratios (LLRs) for channel coded systems in impulsive noise environments is proposed. This approach is to design the LLR detector in the maximum‐likelihood (ML) sense, which requires the parameters of the impulsive noise. The expectation‐maximisation (EM) algorithm is utilised to estimate the parameters of the Bernoulli–Gaussian (B–G) impulsive noise model. The estimated parameters is then used to generate the bit LLRs for the soft‐input channel decoder. Simulation results show that over a wide range of impulsive noise power, the proposed algorithm approaches the optimal performance (with ideal estimation) even under Middleton class‐A (M‐CA) impulsive noise models.
A novel robust fixed‐time fault‐tolerant tracking control of uncertain robot manipulators
Authors: Liu Linzhi , Zhang Liyin , Wang Youming , Hou Yinlong
Published: December 2020

This paper presents a novel robust fixed‐time fault‐tolerant control for global fixed‐time tracking of uncertain robot manipulators with actuator effectiveness faults. With the sufficient consideration of the effects on uncertain dynamics, external disturbances and actuator effectiveness faults to the trajectory tracking performance, a singularity‐free robust fault‐tolerant control with an auxiliary vector is constructed for the fixed‐time tracking control of uncertain robot manipulators. Lyapunov stability theory is employed to prove the global fixed‐time stability ensuring that both the position and velocity tracking errors converge globally to the origin within a fixed time. The appealing advantages of the proposed control are as follows: (i) it is easy to implement with the global robust fixed‐time fault‐tolerant tracking control for uncertain robot manipulators featuring with faster transient convergence rate and higher steady‐state tracking precision; (ii) the settling time is independent of the initial states of closed‐loop system and can be calculated in advance for robot manipulators with uncertain dynamics, external disturbances and actuator faults. Extensive simulations on a two‐DOFs robot are presented to demonstrate the effectiveness and improved performances of the proposed approach.
Multi‐variable finite‐time observer‐based adaptive‐gain sliding mode control for fixed‐wing UAV
Authors: Zhang Chaofan , Zhang Guoshan , Dong Qi
Published: December 2020

This paper presents a multivariable finite‐time observer‐based adaptive‐gain sliding mode control scheme for a fixed‐wing unmanned aerial vehicle (UAV) subject to the unmeasurable angular rates and unknown matched/unmatched disturbance. The control‐oriented model is obtained through the dynamics of fixed‐wing UAV and is composed of attitude subsystem and airspeed subsystem. For the attitude subsystem, a multi‐variable finite‐time observer (MFO) is constructed to achieve the estimation values of unknown states. With the estimation values provided by MFO, a novel adaptive dual‐layer continuous terminal sliding mode (ADL‐CTSM) controller is proposed to track the reference attitude command in finite time. The advantage of the proposed ADL‐CTSM controller is that the bounds of the disturbances are not required and the adaptive gains are obtained as small as possible to attenuate chattering efficiently. For the airspeed subsystem, the tracking differentiator (TD), which enhances the tracking performance, is employed to obtain the smooth reference command and its derivative. The Lipschitz continuous control signal is generated by the designed airspeed controller which is based on the linear proportional‐integral (PI) and the integral of the adaptive‐dual layer twisting algorithm (PIATCI). The rigorous proof of the finite‐time stability of the close‐loop system is provided through Lyapunov criteria and homogeneous technique. Finally, three cases of simulations are carried out to verify the effectiveness and superiority of the proposed control scheme.
Convolutional neural network with batch normalisation for fault detection in squirrel cage induction motor
Authors: Kumar Prashant , Shankar Hati Ananda
Published: December 2020

Early fault detection in an induction motor is the need of modern industries for minimal downtime and maximum production. A learning technique known as the Convolutional Neural network (CNN) provides automated and reliable feature extraction and selection. Considering these inherent traits of CNN, this study proposes a CNN in combination with batch normalisation (BN)‐based fault detection approach for simultaneous detection of bearing fault and broken rotor bars in squirrel cage induction motors (SCIMs). The SCIM vibration signals have different patterns for different defects, and the architecture of CNN is used in this study for fault diagnosis. For an efficient fault feature extraction, the proposed method uses CNN having multiple stacked layers with BN for faster training. In the proposed method, a CNN model with small kernel size is used along with adaptive gradient optimizer and BN to avoid performance degradation and optimum results. For the validation of the proposed technique, a test set‐up is used along with different fault conditions. The proposed method is also compared with the existing state‐of‐the‐art methods to illustrate its effectiveness.
Small‐disturbance stability of a weakly grid‐connected wind farm with multiple PMSGs dominated by the DC‐link voltage dynamics
Authors: Du Wenjuan , Ren Bixing , Wang Haifeng , Chen Jue
Published: December 2020

This study investigates the model‐free assessment of small‐disturbance stability determined by the DC‐link voltage dynamics in a weakly grid‐connected wind farm with M permanent magnet synchronous generators (PMSGs). A reduced‐order model of the PMSG wind farm is established, which is the approximate representation of the wind farm dominated by the DC‐link voltage dynamics. Based on the reduced‐order model, limit of small‐disturbance stability of the PMSG wind farm determined by the DC‐link voltage dynamics is derived. Calculation of derived stability limit does not need to have the parametric model and can be used to approximately assess the small‐disturbance stability of the PMSG wind farm. Hence, the assessment made by using the derived stability limit is model‐free and useful in practice when it is usually difficult to establish the parametric model of the wind farm. In addition, the derived stability limit clearly indicates and explains that when the grid connection weakens or/and the number of PMSGs increases, the DC‐link voltage dynamics are more likely to cause the instability of the PMSG wind farm. In the study, an example AC grid with a grid‐connected PMSG wind farm is presented to demonstrate and evaluate the model‐free assessment of small‐disturbance stability of the wind farm.
Filter‐less power allocation and regulation scheme with the prototypic implementation
Authors: Bhowmik Pritam , Rout Pravat Kumar , Guerrero Josep M.
Published: December 2020

Microgrids are often accomplished with power‐dense and energy‐dense hybrid storage systems for the assured improvement in the stability and the awake time. The conventional droop based steady‐state power bifurcation strategies for the energy‐dense storage elements can efficiently improve the awake time. However, the improvement in the stability and the robustness demands accurate transient demand allocation. The constant cut‐off frequency‐based physical power decomposition filter cannot ensure an accurate transient demand allocation, particularly, while the demand is fluctuating and uncertain. Therefore, the study proposes the concept of pseudo‐power decomposition filter. The concept of the pseudo‐decomposition filter has been executed for the microgrid through the novel selected power component droop. The real‐time performance of the proposed concept has been evaluated in the BTS‐7960 packaged‐Metal Oxide Semiconductor Field Effect Transistor (MOSFET) ‐based hardware platform, regularised through the ARM Cortex A‐72 based digital signal processor. In respect to the conventional linear droop, the improvement through the concept in the power decomposition and the allocation of transient demands is significant.
Coordinated voltage and reactive power control of offshore HVAC meshed grid and wind power
Authors: Wu Qiuwei , Akhmatov Vladislav , Takarics Tibor
Published: December 2020

The Kriegers Flak combined grid solution (KF CGS) is the first hybrid‐asset project utilising an offshore high voltage alternating current/high voltage direct current (HVAC/HVDC) interconnector for large offshore wind power plants between Eastern Denmark and Germany in the Baltic Sea. On the Danish side, above 200 km 220 kV cables are arranged into a meshed offshore transmission grid (MOG). In order to maintain good voltages in the MOG and wind power plants, on the Danish side, the control is realised by an automatic voltage regulation and reactive power control (AVR/RPC) of several switchable and variable reactors and transformers with tap‐position controllers, and the wind power plant controllers (WPPC); on the German side, the voltage control is achieved by the HVDC back‐to‐back converter, WPPC, and part of the optimal power flow by the master controller for interconnector operation. This paper presents the proposed coordinated voltage and RPC of the HVAC MOG on the Danish side of the KF CGS interconnector. The efficiency and constraints of the proposed coordinated control scheme of the KF CGS at fluctuating voltage and reactive power on both ends of the MOG are presented by simulations using the entire set up of the 220 kV AC MOG.
Wind mass transfer in S-type symbiotic binaries
Authors: Shagatova N. , Skopal A. , Shugarov S. Yu. , Komžík R. , Kundra E. , Teyssier F.
Published: December 2020

Context. The structure of the wind from the cool giants in symbiotic binaries carries important information for understanding the wind mass transfer to their white dwarf companions, its fuelling, and thus the path towards different phases of symbiotic-star evolution.

Aims. In this paper, we indicate a non-spherical distribution of the neutral wind zone around the red giant (RG) in the symbiotic binary star, EG And. We concentrate in particular on the wind focusing towards the orbital plane and its asymmetry alongside the orbital motion of the RG.

Methods. We achieved this aim by analysing the periodic orbital variations of fluxes and radial velocities of individual components of the Hα and [O III] λ5007 lines observed on our high-cadence medium (R ∼ 11 000) and high-resolution (R ∼ 38 000) spectra.

Results. The asymmetric shaping of the neutral wind zone at the near-orbital-plane region is indicated by: (i) the asymmetric course of the Hα core emission fluxes along the orbit; (ii) the presence of their secondary maximum around the orbital phase φ = 0.1, which is possibly caused by the refraction effect; and (iii) the properties of the Hα broad wing emission originating by Raman scattering on H0 atoms. The wind is substantially compressed from polar directions to the orbital plane as constrained by the location of the [O III] λ5007 line emission zones in the vicinity of the RG at/around its poles. The corresponding mass-loss rate from the polar regions of ≲10−8 M⊙ yr−1 is a factor of ≳10 lower than the average rate of ≈10−7 M⊙ yr−1 derived from nebular emission of the ionised wind from the RG. Furthermore, it is two orders of magnitude lower than that measured in the near-orbital-plane region from Rayleigh scattering.

Conclusions. The startling properties of the nebular [O III] λ5007 line in EG And provides an independent indication of the wind focusing towards the orbital plane – the key to understanding the efficient wind mass transfer in symbiotic binary stars.
Strongly pulsed thermal X-rays from a single extended hot spot on PSR J2021+4026
Authors: Rigoselli Michela , Mereghetti Sandro , Taverna Roberto , Turolla Roberto , De Grandis Davide
Published: December 2020

The radio-quiet pulsar PSR J2021+4026 is mostly known because it is the only rotation-powered pulsar that shows variability in its γ-ray emission. Using XMM-Newton archival data, we first confirmed that its flux is steady in the X-ray band, and then we showed that both the spectral and timing X-ray properties, that is to say the narrow pulse profile, the high pulsed fraction of 80–90%, and its dependence on the energy, can be better reproduced using a magnetized atmosphere model instead of simply a blackbody model. With a maximum likelihood analysis in the energy-phase space, we inferred that the pulsar has, in correspondence of one magnetic pole, a hot spot with a temperature of T ∼ 1 MK and colatitude extension of θ ∼ 20°. For the pulsar distance of 1.5 kpc, this corresponds to a cap of R ∼ 5 − 6 km, which is greater than the standard dimension of the dipolar polar caps. The large pulsed fraction further argues against emission from the entire star surface, as it would be expected in the case of secular cooling. An unpulsed (≲40% pulsed fraction), nonthermal component, probably originating in a wind nebula, is also detected. The pulsar geometry derived with our spectral fits in the X-ray is relatively well constrained (χ = 90° and ξ = 20°–25°) and consistent with what is deduced from γ-ray observations, provided that only one of the two hemispheres is active. The evidence for an extended hot spot in PSR J2021+4026, which was also found in other pulsars of a similar age but not in older objects, suggests a possible age dependence of the emitting size of thermal X-rays.
Evidence of a predation event on a tagged Mediterranean spearfish (Tetrapturus belone; Pisces, Istiophoridae), inferred from pop-up satellite tagging data
Authors: Malara Danilo , Battaglia Pietro , Consoli Pierpaolo , Arcadi Erika , Canese Simonepietro , Greco Silvestro , Andaloro Franco , Romeo Teresa
Published: December 2020

The Strait of Messina is located at the centre of the Mediterranean Sea and is considered a biodiversity hotspot and an obligatory seasonal passage for different pelagic species such as sharks, marine mammals, and billfishes. For the first time, in the Strait of Messina, our research group tagged a Mediterranean spearfish (Tetrapturus belone) using a pop-up satellite archival tag (PSAT). The observation of abiotic parameters (depth, light, and temperature) recorded by the PSAT confirmed that the tagged specimen was predated after about nine hours. The tag was then regurgitated 14 days after the tag deployment date. The analysis of collected data seems to indicate that the predator may be an ectothermic shark, most likely the bluntnose sixgill shark (Hexanchus griseus).
Transformation of a mathematical model of gas flow distribution to solve the problems of gas supply system development
Authors: Ilkevich Nikolay , Dzyubina Tatyana , Kalinina Zhanna
Published: December 2020

This paper proposes taking into account new properties of gas supply systems in a mathematical model of flow distribution in comparison with the traditional formulation. The approach suggests introducing an arc coefficient, which allows for changes in the magnitude of gas flow passing along the arc, a vector of an increase in the arc throughput, and lower constraints on the gas flow along the arc. We also propose considering a new economic environment, namely, new criteria for optimizing the flow distribution and setting fictitious gas prices for consumers. These criteria enable us to take account of the priority gas supply to a definite group of consumers. As an example, the calculation of gas flows for the aggregated Unified Gas Supply System (UGSS) for 2030 is considered. This calculation takes into account the arc coefficients and the increase in the throughput of arcs.
Search the optimal ratio of system’s component reliability parameters and the heat capacity of prosumers in the district heating system
Authors: Stennikov Valery , Postnikov Ivan
Published: December 2020

The paper presents a methodology for ensuring the reliability of heat supply to prosumer connected to a district heating system, by using the heat capacity of its own heat source and optimization of failure rates of system components. To solve this problem, a mathematical formalization is developed, within which a markov random process, a flow distribution model of the theory of hydraulic circuits, nodal reliability indices, and simplified models of heat transfer processes in heat supply to consumers are used. A case study is considered based on a test scheme of district heating system with prosumer, an analysis of the results obtained is carried out, conclusions and directions for the further research on the subject are formulated.
Design optimisation of labyrinth seals using LES
Authors: Tyacke J.C. , Dai Y. , Watson R. , Tucker P.G.
Published: December 2020

Labyrinth seals are extensively used in gas turbines to control leakage between components. In this research, the effects of geometry on the sealing performance are investigated. To obtain the best sealing performance, an investigation is undertaken into the possibility of optimising labyrinth seal planforms using a genetic algorithm (GA). Large Eddy Simulation (LES) is used for its ability to accurately capture the complex unsteady behaviour of this type of flow. Three hundred LES calculations are carried out. By making use of a large number of processors, an optimum geometry can be achieved within design cycle timescales. The optimised design shows a leakage reduction of 27.6% compared to the baseline geometry. An immersed boundary method (IBM) is used with LES to generate complex geometries on a background Cartesian grid. The GA is inherently parallel, and this enables the exploitation of the reliability and accuracy benefit of LES as demonstrated.
Implantate der weiblichen Brust – Teil 2: Implantatkomplikationen
Authors: Fischer Uwe , Said Hafiez
Published: December 2020

Bei der Diagnostik von Implantaten wird prinzipiell unterschieden zwischen frühen postoperativen und späten Komplikationen. Unmittelbar postoperative Komplikationen betreffen ganz allgemein die Nachblutung, die Wundinfektion und die Wundheilungsstörung. Diese Veränderungen sind in aller Regel klinisch und ggf. durch einen ergänzenden Ultraschall zu diagnostizieren. Bei später auftretenden Komplikationen im Zusammenhang mit dem Implantat kann unterschieden werden zwischen solchen, die eher frühzeitig nach Implantateinbringung entstehen (Rotation, Hernierung, Kapsulitis, Kapselfibrose), und solchen, die sich im Rahmen der Materialermüdung typischerweise erst 10–20 Jahre nach Einbringung des Implantats ausbilden (Gelbluten, Hüllenabhebung, intrakapsuläre und extrakapsuläre Ruptur). Unabhängig hiervon kann es natürlich jederzeit durch die Einwirkung externer Kräfte zu einer Ruptur des Implantats (Silikonaustritt, Silikonom) kommen. In der zweiten der 3-teiligen Präsentation werden die Komplikationen von Implantaten der weiblichen Brust unter besonderer Berücksichtigung der MRT präsentiert.
Langfristige Inzidenz- und Mortalitätstrends für Brustkrebs in Deutschland
Authors: Hübner Joachim , Katalinic Alexander , Waldmann Annika , Kraywinkel Klaus
Published: December 2020

Einleitung Änderungen bei den Risikofaktoren und das 2005 eingeführte Mammografiescreening bedingen eine hohe Dynamik der brustkrebsassoziierten Krankheitslast in Deutschland. Ziel der Studie ist die Untersuchung langfristiger krankheitsbezogener Inzidenz- und Mortalitätstrends bei Frauen in Ost- und Westdeutschland seit der Wiedervereinigung.

Methoden Gesamt- und stadienspezifische Inzidenzraten wurden basierend auf den Daten ausgewählter Krebsregister untersucht. Daten mit hinreichender Vollzähligkeit seit 1995 standen für 4 ostdeutsche und 3 westdeutsche Regionen zur Verfügung. Werte für Gesamtdeutschland wurden populationsgewichtet aus den Raten für Ost- und Westdeutschland errechnet. Besonders betrachtet wurden 3 Altersgruppen: Frauen mit Anspruch auf das Mammografiescreening (50–69 Jahre), jüngere Frauen (30–49 Jahre) und ältere Frauen (70 + Jahre). Alle Raten wurden altersstandardisiert. Entsprechend wurden Mortalitätsraten aus der amtlichen Todesursachenstatistik seit 1990 aufbereitet.

Ergebnisse Im Beobachtungszeitraum kam es zu einem Inzidenzanstieg, der durch die vermehrte Diagnose früher Stadien in der Screeningaltersgruppe geprägt ist. In dieser Gruppe stieg die Gesamtinzidenz unter Einschluss der nichtinvasiven Brustkrebsfälle von 2005 bis 2016 um 14,5 %. Frühe Stadien (UICC 0 und I) nahmen um 48,1 % zu, während Spätstadien (UICC III und IV) um 31,6 % zurückgingen. In den anderen Altersgruppen kam es zu qualitativ ähnlichen Veränderungen, die jedoch weniger stark ausgeprägt waren. Der seit Mitte der 90er-Jahre zu beobachtende Rückgang der Brustkrebssterblichkeit endete bei den jüngeren Frauen um 2008, während er sich in der Screeningaltersgruppe fortsetzte. Bei älteren Frauen kam es nach 2008 zu einem Anstieg. Ost-West-Unterschiede bei der Krankheitslast (zugunsten Ostdeutschlands) nahmen bei den jüngeren Frauen im Beobachtungszeitraum ab, während sie bei den älteren Frauen eher zunahmen.

Schlussfolgerung Die Analyse legt nahe, dass die Einführung des Mammografiescreenings zum Rückgang der Inzidenz fortgeschrittener Brustkrebsstadien und der Brustkrebsmortalität beigetragen, aber auch eine substanzielle Zahl von Überdiagnosen verursacht hat. Relativ ungünstige Inzidenztrends bei jüngeren Frauen, insbesondere in Ostdeutschland, sind vor dem Hintergrund von Lebensstiländerungen zu interpretieren. Die beobachtete leichte Zunahme der Mortalität bei älteren Frauen seit 2008 bedarf eingehenderer Analysen.
Übersicht über die Endoprothetik an den Fingergrund- und Mittelgelenken
Authors: Keller Marco , Gübeli Alissa , Honigmann Philipp
Published: December 2020

Hintergrund Arthrotische Veränderungen der Fingergelenke sind häufig, insbesondere in der älteren Population. Unbehandelt können diese zu Schmerzen, Deformität, Instabilität oder Bewegungseinschränkung führen. Nebst Denervation und Arthrodese ist der prothetische Gelenkersatz eine mögliche operative Behandlungsmethode.

Patienten/Material und Methode Während der letzten Jahrzehnte erschienen diverse Prothesenmodelle zum Gelenkersatz des Fingergrund- und -mittelgelenkes auf dem Markt. Dieser Artikel bietet eine Übersicht über deren Entwicklung, heutige Prothesenmodelle, klinische Ergebnisse sowie zukunftsträchtige technische Neuheiten.

Ergebnisse Der seit den 1960er Jahren erhältliche Silikonspacer bleibt aufgrund guter klinischer Langzeitergebnisse, niedriger Revisionsraten sowie günstiger Kosten das Implantat der Wahl. Am Zeige- und Mittelfinger ist die laterale Stabilität wichtig, um dem Daumen beim Präzisionsgriff ein Widerlager zu bieten. Medullär verankernde Prothesen und modulare Oberflächenersatz-Prothesen können hier durch ihre erhöhte intrinsische Stabilität einen Vorteil bieten. Neue derartige Implantate zeigen vielversprechende mittelfristige klinische Ergebnisse.

Schlussfolgerung Obwohl sich die technischen Fortschritte auf dem Gebiet der Endoprothetik der großen Gelenke in der Vergangenheit nur bedingt auf die der Fingergelenke und der restlichen Hand übertragen ließen, gewinnen langsam auch Neuheiten wie patientenspezifische oder auf 3D-Druck-Technologie basierende Implantate an Bedeutung.
COVID-19: Intensivmedizinische Aspekte und Langzeitfolgen
Authors: Bruno Raphael Romano , Wolff Georg , Kelm Malte , Jung Christian
Published: December 2020

Etwa 14% der COVID-19-Patienten weisen einen schwereren und ca. 5% einen kritischen Krankheitsverlauf auf. Besonders gefährdet sind ältere Personen, männliches Geschlecht, Raucher und stark adipöse Menschen. Wird der Patient invasiv oder nichtinvasiv beatmet, so steigt die Mortalität auf 53% respektive 50% an. In der Regel beträgt die Dauer vom Beginn der Symptome bis zur Aufnahme auf die Intensivstation 10 Tage. Die mittlere Verweildauer auf der Intensivstation beträgt 9 Tage. Für die Priorisierung sind die klinische Erfolgsaussicht einer intensivmedizinischen Behandlung sowie der Wunsch des Patienten maßgebend. Zentrale Kriterien für die Aufnahme auf die Intensivstation sind eine Hypoxämie (SpO2 < 90% unter 2 – 4 Liter Sauerstoff/min bei nicht vorbestehender Therapie), Dyspnoe, eine erhöhte Atemfrequenz (> 25 – 30/min) und ein systolischer Blutdruck ≤ 100 mmHg. Der Schutz des Personals genießt bei allen Maßnahmen Vorrang. Alle aerosolgenerierenden
Prozeduren sollten nur mit großer Vorsicht erfolgen. Wird unter High Flow keine adäquate Oxygenierung erreicht (SpO2 ≥ 90% oder ein paO2 > 55 mmHg), sollte über eine Eskalation nachgedacht werden (NIV, invasive Beatmung). Die Patienten sollten lungenprotektiv beatmet werden. Die Intubation sollte als Rapid Sequence Induction erfolgen. Eine ECMO kann erwogen werden. Thrombembolische Komplikationen sind sehr häufig. Antibiotika sollten nicht routinemäßig gegeben werden. Die aktuell beste Datenlage liegt für Dexamethason vor. Remdesivir kann die Rekonvaleszenz beschleunigen. Langzeitfolgen nach COVID-19 sind sehr häufig. Kardiale, pulmonale und neurologische Probleme stehen dabei im Vordergrund.
Precursor-directed Biosynthesis in Tabernaemontana catharinensis as a New Avenue for Alzheimerʼs Disease-modifying Agents
Authors: Musquiari Bruno , Crevelin Eduardo J. , Bertoni Bianca W. , França Suzelei de C. , Pereira Ana Maria S. , Castello Ana Carolina Devides , Castillo-Ordoñez Willian O. , Giuliatti Silvana , Lopes Adriana A.
Published: December 2020

Plants produce a high diversity of metabolites that can act as regulators of cholinergic dysfunction. Among plants, the potential of species of the genus Tabernaemontana to treat neurological disorders has been linked to iboga-type alkaloids that are biosynthesized by those species. In this context, precursor-directed biosynthesis approaches were carried out using T. catharinensis plantlets to achieve new-to-nature molecules as promising agents against Alzheimerʼs disease. Aerial parts of T. catharinensis, cultured in vitro, produced 7 unnatural alkaloids (5-fluoro-ibogamine, 5-fluoro-voachalotine, 5-fluoro-12-methoxy-Nb-methyl-voachalotine, 5-fluoro-isovoacangine, 5-fluoro-catharanthine, 5-fluoro-19-(S)-hydroxy-ibogamine, and 5-fluoro-coronaridine), while root extracts showed the presence of the same unnatural iboga-type alkaloids and 2 additional ones: 5-fluoro-voafinine and 5-fluoro-affinisine. Moreover, molecular docking approaches were carried
out to evaluate the potential inhibition activity of T. catharinensis’ natural and unnatural alkaloids against AChE and BChE enzymes. Fluorinated iboga alkaloids (5-fluoro-catharanthine, 5-fluoro-voachalotine, 5-fluoro-affinisine, 5-fluoro-isovoacangine, 5-fluoro-corinaridine) were more active than natural ones and controls against AchE, while 5-fluoro-19-(S)-hydroxy-ibogamine, 5-fluoro-catharanthine, 5-fluoro-isovoacangine, and 5-fluoro-corinaridine showed better activity than natural ones and controls against BChE. Our findings showed that precursor-directed biosynthesis strategies generated “new-to-nature” alkaloids that are promising Alzheimerʼs disease drug candidates. Furthermore, the isotopic experiments also allowed us to elucidate the initial steps of the biosynthetic pathway for iboga-type alkaloids, which are derived from the MEP and shikimate pathways.
Oxidative C–H Acyloxylation of Acetone with Carboxylic Acids under Iodine Catalysis
Authors: Zhou Xiao-Yu , Chen Xia
Published: December 2020

Iodine-catalyzed oxidative C(sp3)–H acyloxylation of acetone with carboxylic acids has been developed. The method employs iodide­ as catalyst and sodium chlorite as oxidant. Substituted benzoic acids, naphthoic acids and heteroaromatic carboxylic acids can be used, and 2-oxopropyl carboxylates are obtained with good to excellent yields.
Advances in Carbon–Element Bond Construction under Chan–Lam Cross-Coupling Conditions: A Second Decade
Authors: Vijayan Ajesh , Rao Desaboini Nageswara , Radhakrishnan K. V. , Lam Patrick Y. S. , Das Parthasarathi
Published: December 2020

Copper-mediated carbon–heteroatom bond-forming reactions involving a wide range of substrates have been in the spotlight for many organic chemists. This review highlights developments between 2010 and 2019 in both stoichiometric and catalytic copper-mediated reactions, and also examples of nickel-mediated reactions, under modified Chan–Lam cross-coupling conditions using various nucleophiles; examples include chemo- and regioselective N-arylations or O-arylations. The utilization of various nucleophiles as coupling partners together with reaction optimization (including the choice of copper source, ligands, base, and other additives), limitations, scope, and mechanisms are examined; these have benefitted the development of efficient and milder methods. The synthesis of medicinally valuable or pharmaceutically important nitrogen heterocycles, including isotope-labeled compounds, is also included. Chan–Lam coupling reaction can now form twelve different C–element bonds, making it one of the most diverse and mild reactions known in organic chemistry.

1 Introduction

2 Construction of C–N and C–O Bonds

2.1 C–N Bond Formation

2.1.1 Original Discovery via Stoichiometric Copper-Mediated C–N Bond Formation

2.1.2 Copper-Catalyzed C–N Bond Formation

2.1.3 Coupling with Azides, Sulfoximines, and Sulfonediimines as Nitrogen­ Nucleophiles

2.1.4 Coupling with N,N-Dialkylhydroxylamines

2.1.5 Enolate Coupling with sp3-Carbon Nucleophiles

2.1.6 Nickel-Catalyzed Chan–Lam Coupling

2.1.7 Coupling with Amino Acids

2.1.8 Coupling with Alkylboron Reagents

2.1.9 Coupling with Electron-Deficient Heteroarylamines

2.1.10 Selective C–N Bond Formation for the Synthesis of Heterocycle-Containing Compounds

2.1.11 Using Sulfonato-imino Copper(II) Complexes

2.2 C–O Bond Formation

2.2.1 Coupling with (Hetero)arylboron Reagents

2.2.2 Coupling with Alkyl- and Alkenylboron Reagents

3 C–Element (Element = S, P, C, F, Cl, Br, I, Se, Te, At) Bond Forma tion under Modified Chan–Lam Conditions

4 Conclusions