bluuebunny/crossref_metadata_2025 huggingface dataset:
Low molecular weight silicones induce cell death in cultured cells
Authors: Onnekink Carla , Kappel Rita M. , Boelens Wilbert C. , Pruijn Ger J. M.
Published: June 2020

Women with silicone gel-filled breast implants are exposed to organosilicon compounds, in particular methylsiloxanes, as a result of ‘gel bleed’ and implant rupture. Although these silicones were originally considered to be inert, increasing evidence indicates that they can cause serious health problems. Here, we have analyzed the effects of microdroplets of the methylcyclosiloxanes, in particular D4, on the viability of cultured human cells. The exposure of Jurkat suspension and HeLa monolayer cells to D4 resulted in morphological changes of the cells. The analysis of molecular markers for apoptotic and necrotic processes not only demonstrated that caspases were activated and DNA was fragmented in Jurkat cells exposed to D4, but that also the permeability of the plasma membrane was altered. The induction of apoptotic pathways by D4 was substantiated by the inhibition of caspase activation in cells overexpressing Bcl-2. Cleavage of the caspase-3 substrate U1-70K appeared to be dependent on the D4 content and the efficiency of cleavage decreased with increasing size of the methylcyclosiloxanes (D4, D5 and D6). In addition to Jurkat cells, D4-induced U1-70K cleavage was also observed in HeLa cells, but not in HEp-2 cells. Taken together, these results indicate that D4 and, to a lesser extent, D5 can activate cell-death-related pathways in a cell type-specific fashion and suggest that this phenomenon may contribute to the development of Breast Implant Illness.
Convolutional-neural-network-based diagnosis of appendicitis via CT scans in patients with acute abdominal pain presenting in the emergency department
Authors: Park Jin Joo , Kim Kyung Ah , Nam Yoonho , Choi Moon Hyung , Choi Sun Young , Rhie Jeongbae
Published: June 2020

Acute appendicitis is one of the most common causes of abdominal emergencies. We investigated the feasibility of a neural-network-based diagnosis algorithm of appendicitis by using computed tomography (CT) for patients with acute abdominal pain visiting the emergency room (ER). A neural-network-based diagnostic algorithm of appendicitis was developed and validated using CT data from three institutions who visited the ER with abdominal pain and underwent abdominopelvic CT. For input data, 3D isotropic cubes including the appendix were manually extracted and labeled as appendicitis or a normal appendix. A 3D convolutional neural network (CNN) was trained to binary classification on the input. For model development and testing, 8-fold cross validation was conducted for internal validation and an ensemble model was used for external validation. Diagnostic performance was excellent in both the internal and external validation with an accuracy larger than 90%. The CNN-based diagnosis algorithm may be feasible in diagnosing acute appendicitis using the CT data of patients visiting the ER with acute abdominal pain.
Investigations on the complex flows induced by dual-swept/dual-ramp wedges in supersonic flows
Authors: Gao X. , Xiang G. X. , Tang W. J. , Jie X. Z. , Huang X. , He J. Y. , Liu S. A.
Published: June 2020

The caret inlet with a dual-swept/dual-ramp configuration has excellent stealth performance and aerodynamic capability. Most previous investigations on this configuration have focused on experiments and numerical simulations but there are relatively few theoretical investigations. In this study, the flow field characteristics of dual-swept/dual-ramp configuration are investigated analytically and numerically. An analytical approach that combines the shock dynamics with a “spatial dimension reduction” was used to analyze the characteristics of the wave structures and state parameters of the flow field. The effects of the sweep angles and inflow Mach number on the flow field characteristics are investigated. The results indicate that the problem of shock/shock interaction in two intersecting wedges of large back-swept angle is a problem of weak shock interaction. Therefore, the theory of weak shock interaction is used to investigate the flow field characteristics, including the uniformity of the flow field and the total pressure recovery performance.
Author Correction: The in vitro inertial positions and viability of cells in suspension under different in vivo flow conditions
Authors: Connolly Sinead , McGourty Kieran , Newport David
Published: June 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Publisher Correction: Seagrass can mitigate negative ocean acidification effects on calcifying algae
Authors: Bergstrom Ellie , Silva João , Martins Cíntia , Horta Paulo
Published: June 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Physiological and ecological characteristics of Periploca sepium Bunge under drought stress on shell sand in the Yellow River Delta of China
Authors: Wang Xiao , Xia Jiang-Bao , Cao Xue-Bin
Published: June 2020

This study investigated the physiological and ecological changes in P. sepium Bunge and elucidated the physiological regulatory mechanisms underlying the adaptation of P. sepium to drought stress in shell sand. Drought stress led to a significant decrease in the net photosynthesis rate (Pn) and respiration rate of leaves and a decrease in low-intensity light-use efficiency (LUE) and light ecological amplitude. An increase in drought stress led to a considerable decrease in the photosynthetic electron transport rate in the P. sepium leaves and a significant increase in the amount of light energy dissipated as heat. In addition, the photosynthesis process suffered from severe photoinhibition. P. sepium plants counteracted the effects of drought stress primarily by increasing their peroxidase (POD) activity and by regulating membrane lipid peroxidation by secreting greater numbers of osmotic adjustment substances (proline (Pro) and soluble sugars (Ss)) and malondialdehyde (MDA). As drought stress increased, both the stem sap flow rate and the cumulative sap flow of P. sepium decreased considerably. P. sepium Bunge adapts to drought stress through interregulatory activity between photosynthesis, water-related physiological activities, and physiological and biochemical processes, and this species exhibits relatively high adaptive plasticity to drought.
Systemic hypertension associated retinal microvascular changes can be detected with optical coherence tomography angiography
Authors: Sun Christopher , Ladores Carlo , Hong Jimmy , Nguyen Duc Quang , Chua Jacqueline , Ting Daniel , Schmetterer Leopold , Wong Tien Yin , Cheng Ching-Yu , Tan Anna C. S.
Published: June 2020

A major complication of hypertension is microvascular damage and capillary rarefaction is a known complication of hypertensive end-organ damage which confers a higher risk of systemic disease such as stroke and cardiovascular events. Our aim was to study the effect of hypertension on the retinal microvasculature using non-invasive optical coherence tomography angiography (OCTA). We performed a case-control study of 94 eyes of 94 participants with systemic hypertension and 46 normal control eyes from the Singapore Chinese Eye Study using a standardized protocol to collect data on past medical history of hypertension, including the number and type of hypertensive medications and assessed mean arterial pressure. Retinal vascular parameters were measured in all eyes using OCTA. In the multivariate analysis adjusting for confounders, compared to controls, eyes of hypertensive patients showed a decrease in the macular vessel density at the level of the superficial [OR 0.02; 95% CI, 0 to 0.64; P 0.027] and deep venous plexuses [OR 0.03; 95% CI, 0 to 0.41; P 0.009] and an increase in the deep foveal avascular zone. This shows that hypertension is associated with reduced retinal vessel density and an increased foveal avascular zone, especially in the deep venous plexus, as seen on OCTA and there is a potential role in using OCTA as a clinical tool to monitor hypertensive damage and identifying at risk patients
Sub-picosecond photo-induced displacive phase transition in two-dimensional MoTe2
Authors: Peng Bo , Zhang Hao , Chen Weiwen , Hou Bowen , Qiu Zhi-Jun , Shao Hezhu , Zhu Heyuan , Monserrat Bartomeu , Fu Desheng , Weng Hongming , Soukoulis Costas M.
Published: June 2020

Photo-induced phase transitions (PIPTs) provide an ultrafast, energy-efficient way for precisely manipulating the topological properties of transition-metal ditellurides and can be used to stabilize a topological phase in an otherwise semiconducting material. Using first-principles calculations, we demonstrate that the PIPT in monolayer MoTe2 from the semiconducting 2H phase to the topological 1T′ phase can be triggered purely by electronic excitations that soften multiple lattice vibrational modes. These softenings, driven by a Peierls-like mechanism within the conduction bands, lead to structural symmetry breaking within sub-picosecond timescales, which is shorter than the timescale of a thermally driven phase transition. The transition is predicted to be triggered by photons with energies over 1.96 eV, with an associated excited carrier density of 3.4 × 1014 cm−2, which enables a controllable phase transformation by varying the laser wavelength. Our results provide insight into the underlying physics of the phase transition in 2D transition-metal ditellurides and show an ultrafast phase-transition mechanism for manipulation of the topological properties of 2D systems.
The surprisingly high activation barrier for oxygen-vacancy migration in oxygen-excess manganite perovskites
Authors: Börgers Jacqueline M. , De Souza Roger A.
Published: June 2020

Cation vacancies diminish the oxygen-vacancy diffusivity, raise the activation enthalpy, and cause the diffusivity to depend on oxygen activity.
Reconciling MA′AT and molecular dynamics models of linkage conformation in oligosaccharides
Authors: Meredith Reagan J. , Woods Robert J. , Carmichael Ian , Serianni Anthony S.
Published: June 2020

MA′AT conformational models of the phi torsion angles ofO-glycosidic linkages differ from those obtained from MD simulation.
Solving the Schrödinger equation of the hydrogen molecule with the free-complement variational theory: essentially exact potential curves and vibrational levels of the ground and excited states of Π symmetry
Authors: Kurokawa Yusaku I. , Nakashima Hiroyuki , Nakatsuji Hiroshi
Published: June 2020

Following a previous study of the Σ states (Phys. Chem. Chem. Phys., 2019, 21, 6327), we solved the Schrödinger equation (SE) of the hydrogen molecule in the ground and excited Π states using the free complement (FC) variational method.
The introduction of functional side groups and the application of the mixed-linker concept in divalent MIL-53(Ni) materials
Authors: Bitzer Johannes , Titze-Alonso Alba , Roshdy Abdelkarim , Kleist Wolfgang
Published: June 2020

Divalent MIL-53(Ni) metal–organic frameworks with 2-bromoterephthalate and terephthalate linkers feature interesting material properties as proven by various characterization techniques.
Metal–organic frameworks for solid-state electrolytes
Authors: Zhao Ruo , Wu Yingxiao , Liang Zibin , Gao Lei , Xia Wei , Zhao Yusheng , Zou Ruqiang
Published: June 2020

This perspective highlights the application of MOFs for solid-state electrolytes, emphasizing their advantages, challenges and future directions.
Engineering a chemoenzymatic cascade for sustainable photobiological hydrogen production with green algae
Authors: Chen Jie , Li Jiang , Li Qian , Wang Shuai , Wang Lihua , Liu Huajie , Fan Chunhai
Published: June 2020

A chemoenzymatic cascade (CEC) composed of glucose, glucose oxidase (GOx), catalase (CAT), and Mg(OH)2 enabled C. reinhardtii-based sustainable and efficient H2 production for up to 26 days with ordinary TAP medium under continuous irradiation.
Hydrogen bonding rather than cation bridging promotes graphene oxide attachment to lipid membranes in the presence of heavy metals
Authors: Li Huimin , Ji Haodong , Zhang Ruijie , Zhang Wei , Pan Baozhu , Liu Wen , Sun Weiling
Published: June 2020

GO first binds with metals, and GO–metal complexes attach to SSLBs via hydrogen bonding through GO rather than cation bridging through metals.
Perfluorocarbon nanodroplets stabilized with cisplatin-prodrug-constructed lipids enable efficient tumor oxygenation and chemo-radiotherapy of cancer
Authors: Yao Li , Feng Liangzhu , Tao Danlei , Tao Huiquan , Zhong Xiaoyan , Liang Chao , Zhu Yujie , Hu Bing , Liu Zhuang , Zheng Yuanyi
Published: June 2020

Concurrent chemo-radiotherapy has been widely applied for the treatment of a wide range of cancers, but its therapeutic efficacy against most solid tumors is severely impaired by their intrinsic hypoxic microenvironments.
An ab initio approach on the asymmetric stacking of GaAs 〈111〉 nanowires grown by a vapor–solid method
Authors: Yeu In Won , Han Gyuseung , Hwang Cheol Seong , Choi Jung-Hae
Published: June 2020

This study provides an ab initio thermodynamics approach to take a step forward in the theoretical modeling on the growth of GaAs nanowires.
Strain mapping inside an individual processed vertical nanowire transistor using scanning X-ray nanodiffraction
Authors: Dzhigaev Dmitry , Svensson Johannes , Krishnaraja Abinaya , Zhu Zhongyunshen , Ren Zhe , Liu Yi , Kalbfleisch Sebastian , Björling Alexander , Lenrick Filip , Balogh Zoltan Imre , Hammarberg Susanna , Wallentin Jesper , Timm Rainer , Wernersson Lars-Erik , Mikkelsen Anders
Published: June 2020

Scanning X-ray nanodiffraction applied to map the strain field inside a realistic nanowire transistor embedded in device processing layers.
On interfacial viscosity in nanochannels
Authors: Nazari Masoumeh , Davoodabadi Ali , Huang Dezhao , Luo Tengfei , Ghasemi Hadi
Published: June 2020

Capillary flow is omnipresent in nature and technology and its dynamics strongly depend on liquid viscosity. The enhanced viscosity in nanochannels can be attributed to an interfacial layer with a viscosity significantly larger than bulk liquid.
High-temperature and multichannel quantum anomalous Hall effect in pristine and alkali–metal-doped CrBr3 monolayers
Authors: Zhang Huisheng , Yang Wenjia , Ning Yaohui , Xu Xiaohong
Published: June 2020

We provide an experimentally achievable guide for realizing the high-temperature and multichannel QAHE in prinstine and Na-doped CrBr3 monolayer.
Correction: Research status, industrial application demand and prospects of phenolic resin
Authors: Xu Yanru , Guo Lifang , Zhang Haonan , Zhai Huamin , Ren Hao
Published: June 2020

Correction for ‘Research status, industrial application demand and prospects of phenolic resin’ by Yanru Xu et al., RSC Adv., 2019, 9, 28924–28935. DOI: 10.1039/C9RA06487G.
Anomalous and heterogeneous DNA transport in biomimetic cytoskeleton networks
Authors: Garamella Jonathan , Regan Kathryn , Aguirre Gina , McGorty Ryan J. , Robertson-Anderson Rae M.
Published: June 2020

The cytoskeleton, a complex network of protein filaments and crosslinking proteins, dictates diverse cellular processes ranging from division to cargo transport.
Efficient electroosmotic mixing in a narrow-fluidic channel: the role of a patterned soft layer
Authors: Gaikwad Harshad Sanjay , Kumar Gaurav , Mondal Pranab Kumar
Published: June 2020

We propose a novel and efficient mixing technique in a soft narrow-fluidic channel under the influence of electrical forcing.
A Tutorial on Saliva's Role in Swallowing With a Focus on Sjögren's Syndrome
Authors: Letawsky Veronica H. , Schreiber Ann-Marie , Skoretz Stacey A.
Published: June 2020

Purpose

Saliva is integral to swallowing and necessary for oral health. Understanding saliva's origin and properties is important for swallowing assessment and management. Diseases such as Sjögren's syndrome (SS) can affect saliva negatively, often contributing to dysphagia. Our objectives are to (a) highlight saliva's fundamental role in swallowing, (b) provide a bibliometric overview of literature pertaining to SS pathophysiology and effects on saliva, (c) explore implications of salivary changes on swallowing and quality of life in SS and other populations, and (d) provide suggestions for systematic saliva assessment in practice.

Method

This tutorial reviews saliva production, composition, and involvement in swallowing within health and disease. Using rapid review methodology, we outline the effect of SS on saliva and describe SS etiology, diagnosis, and treatment. We discuss formal saliva assessments and a multidisciplinary approach.

Results

Saliva plays a vital role in swallowing, particularly lubrication, bolus formation, and oral health. SS affects the salivary glands altering salivary flow rate and composition. We identified 55 studies (
N
) measuring salivary changes, grouping them according to four strata demarcated by SS classification criteria updates. For some, xerostomia, dysphagia, and reduced life quality result. Formal saliva assessments include the Clinical Oral Dryness Score, Xerostomia Inventory, and Secretion Rating Scale. Multidisciplinary care is optimal for patients with salivary changes.

Conclusion

Understanding salivary changes in disease may enhance understanding of swallowing and inform dysphagia practice. Expanding swallowing assessments with formal saliva evaluations, and patient perspectives thereof, may aid in developing bespoke treatments, ultimately improving outcomes and quality of life.

Supplemental Material

https://doi.org/10.23641/asha.12456449
Time of arrival estimation based on clustering for positioning in OFDM system
Authors: Zhang Zhenyu , Kang Shaoli
Published: June 2020

In positioning research based on the orthogonal frequency division multiplex (OFDM) system, the observed time difference of arrival positioning method is a widely studied direction. The terminal measures the reference signal sent by the base station to calculate the time of arrival (TOA). Using TOA information, the location of the terminal can be identified. So the accuracy of the positioning is highly dependent on the results of the TOA measurements. Terminals often have difficulty measuring accurate TOA due to multipath channels and occlusion of obstacles. This study proposes two clustering‐based TOA estimation methods. The cluster‐based Max‐peak estimator is used to solve the problem that the energy of the first‐path is not the strongest in the case of multipath. Moreover, a cluster‐based adaptive threshold estimator is used to estimate TOA when the power of the direct path is low. The joint estimator of the two methods is designed to improve estimation accuracy. The proposed method is tested in the OFDM localisation environment, and the results demonstrate that the proposed method has better performance than the conventional way.
Secure polar coding with delayed wiretapping information
Authors: Zhao Yizhi , Chi Hongmei
Published: June 2020

In this study, the authors investigate the secure coding issue for a wiretap channel model with fixed main channel and varying wiretap channel, by assuming that legitimate parties can obtain the wiretapping channel state information (CSI) with some delay. For the symmetric degraded delay CSI case, they present an explicit weak security scheme by constructing secure polar codes on a one‐time pad chaining structure, and prove its weak security, reliability and capability of approaching the secrecy capacity for perfect CSI case with delay CSI assumption. Further for the symmetric no‐degraded delay CSI case, they present a modified multi‐block chaining structure in which the original subset of frozen bit is designed for conveying functional random bits securely. Then they combine this modified multi‐block chaining structure with the weak security scheme to construct an explicit strong security polar coding scheme, and prove its strong security, reliability and also the capability of approaching the secrecy capacity for perfect CSI case with delay CSI assumption. At last, they carry out simulations to prove the performance of both secure schemes.
Frequency synchronisation for massive MIMO: a survey
Authors: Jeong Sumin , Farhang Arman , Gao Feifei , Flanagan Mark F.
Published: June 2020

Massive multiple‐input multiple‐output (MIMO) is currently entering the practical implementation phase, and key implementation issues for this technology have yet to be fully addressed. Crucial among these is the practical problem of frequency synchronisation, which refers to the adjustment of the clock frequency of local nodes to the clock frequency of a reference node by estimating and compensating carrier frequency offset. Existing theoretical studies on massive MIMO generally assume perfect frequency synchronisation; however, the potentially very high complexity of this process poses a major challenge for massive MIMO systems. Therefore, new frequency synchronisation techniques are urgently needed to make the practical implementation of massive MIMO feasible. In this study, the authors provide a comprehensive classification of the existing research efforts along this line, considering different antenna architectures and modulation schemes. They also highlight the key challenges in frequency synchronisation for massive MIMO, and they outline future research directions on this topic.
Secondary‐control‐based harmonics compensation scheme for voltage‐ and current‐controlled inverters in islanded microgrids
Authors: Mousazadeh Mousavi Seyyed Yousef , Jalilian Alireza , Savaghebi Mehdi , Guerrero Josep M.
Published: June 2020

In this study, a coordinated control scheme is proposed for sharing harmonics compensation effort among voltage and current controlled mode (VCM and CCM) inverters in islanded microgrids. In this method, the voltage harmonics compensation of sensitive bus (SB) is achieved by using secondary control as well as virtual impedance and admittance loops in primary control of VCM and CCM units. The limited capacity of the inverter is taken into account for harmonics compensation. Photovoltaic (PV) systems are considered as CCM units. The harmonics compensation is mainly performed by VCM inverters. However, in order to prevent these units from overloading, the PV interfacing inverters (CCM units) are called to collaborate in harmonics compensation whenever needed. The results of simulation study in Matlab/Simulink show the effectiveness of this method in coordination of CCM and VCM units.
Observer‐based sliding‐mode control of a DC/DC buck converter for railway systems
Authors: Lin Hao , Liu Jianxing , Leon Jose Ignacio , Marquez Abraham , Luo Wensheng , Franquelo Leopoldo G.
Published: June 2020

DC/DC power converters are critical parts of railway applications because they are required in on‐board, off‐board, and communication systems. Traditionally sliding‐mode control is only insensitive to the matched disturbances, and the system performance is reduced when mismatched disturbances appear. This study develops a non‐linear disturbance observer (NDO)‐based adaptive non‐singular fast terminal sliding‐mode control strategy for DC/DC buck converter with mismatched disturbances. The proposed strategy exhibits the following three attractive features. Firstly, the observer can estimate the matched and mismatched disturbances in finite time. Next, by taking the estimations of the disturbances into account, a sliding‐mode variable is designed, the system reach the sliding‐mode surface in finite time, and the output voltage tracking error converges to zero in finite time. Then, the convergence rates of the sliding‐mode variable and output voltage tracking error are faster compared with those of the NDO‐based non‐singular terminal sliding‐mode (NTSM) controller. Finally, with the adaptive law, the control gain is adjusted to an appropriate value with respect to disturbances, and the chattering of the control signal is reduced. Experimental results show that comparing with the NDO‐based NTSM controller, the proposed method exhibits better steady‐state performance and dynamic performance including robustness and disturbance rejection ability.
Recent advances in nanodentistry: a special focus on endodontics
Authors: Mohammadi Fatemeh , Abbaszadegan Abbas , Gholami Ahmad
Published: June 2020

Root canal ecosystem is a complex environment due to its anatomy and persistence of microorganisms; those may reside within the canal after therapeutic efforts and cause subsequent complications and treatment failure. Nanomaterials with unique physicochemical properties have high accessibility to untouched areas of the intracanal ecosystem. Therefore, they have attracted the attention of researchers on the efficacy of nanodentistry in endodontics. This Letter reviews the recent advances in nanodentistry, especially in root canal treatment. In addition, it focuses on the application of nanoparticles in treatment and prevention of a variety of post‐treatment infections in endodontics, treatment of antibiotic resistance and bacterial biofilm structures. In addition, it points out applications of nanoparticles in endodontic materials, restorative materials, dental adhesives, implants, prostheses and dentures. At last, the Letter elaborates on how nanoparticles used for targeted endodontic drug delivery and their efficiently controlled releases.
Synthesis of Cu2ZnSnSe4 thin‐film solar cells from nanoparticles by a non‐vacuum mechanical ball milling and rapid thermal processing
Authors: Liu Ying , Xu Xiaowei , Liu Ke , Liu Huihong
Published: June 2020

A truly simple, reproducible, and environmentally friendly non‐vacuum synthesis method for synthesising of carbon‐free Cu2ZnSnSe4 (CZTSe) absorber layer has been presented. The stannite CZTSe nanoparticles with an average size of about 20 nm distributions were fabricated by an ambient mechanical milling procedure using Cu2Se, Zn, Sn, elemental selenium powders as raw materials and non‐toxic ethanol as solvent. The compact CZTSe thin films were formed via an annealing treatment under Ar/Se atmosphere using rapid thermal processing. The optical properties of the obtained CZTSe thin films are the absorption coefficient (α) exceeding 104 cm−1 and Eg of 0.91 eV. The electrical properties of the CZTSe thin films indicate p‐type semiconductor behaviour. The photovoltaic properties of this solar cell are power conversion efficiency of 0.18%.
Pulsed plasma chemical synthesis of Fe2O3@TiO2 core–shell nanocomposites
Authors: Kholodnaya Galina , Sazonov Roman , Ponomarev Denis , Sivkov Alexander , Shanenkov Ivan , Konusov Fedor , Gadirov Ruslan
Published: June 2020

The Letter presents the results of the experimental investigation on the synthesis of core–shell structured nanocomposites. Iron oxide, which served as a nucleus in the composite, was synthesised using the plasma dynamic method. The composite shell was titanium oxide produced by the pulsed plasma chemical method. Average sizes of nanoparticles were estimated between 50 and 150 nm in the Fe2O3@TiO2 core–shell structured composite nanoparticles using TEM. A distinctive feature of the morphology of the synthesised Fe2O3@TiO2 core–shell is that the core entirely encapsulates clusters of titanium oxide nanoparticles. The wall thickness of the coating is 5–10 nm. The spectral dependence of the absorption coefficient α(hν) was calculated for the Fe2O3@TiO2 composite. The interband absorption parameters are determined in the energy intervals Δ′(hν) upon approximation of the absorption spectra. The bandgap for indirect and direct allowed transitions is 1.36 and 1.97 eV for and , respectively.
Highly stable Au/Ag core–shell nanoparticles prepared via novel green approach for the abatement of nitro pollutants
Authors: Verma Vishal , Singh Maninder , Pal Singh Prit , Singh Jagpreet , Rawat Mohit
Published: June 2020

The development of a benign, cost‐effective and eco‐friendly system for the removal of pollutants from water is an ongoing challenge. In this regard, the authors first time explored a clean and sustainable mean for the synthesis of Au/Ag core–shell nanoparticles (NPs) using Ananas comosus leaves extract as a reducing and stabilising agent. Spectroscopic and microscopic techniques confirmed the formation of Au/Ag core–shell NPs with an average size range between 5 and 10 nm. The synthesised Au/Ag core–shell NPs showed the excellent catalytic potential for the reduction of 4‐nitrophenol into 4‐aminophemol within 15 min. Kinetic study explicates that the catalytic reaction obeys the pseudo‐first‐order kinetic law with an apparent rate constant (kapp) of 0.03 min−1. Moreover, Au–Ag core–shell NPs showed exceptional stability over a long period (three months). Thus, this study provides a positive step towards the development of novel green catalysts.
Ionization: a possible explanation for the difference of mean disk sizes in star-forming regions
Authors: Kuffmeier M. , Zhao B. , Caselli P.
Published: June 2020

Context. Surveys of protoplanetary disks in star-forming regions of similar age revealed significant variations in average disk mass in some regions. For instance, disks in the Orion Nebular Cluster (ONC) and Corona Australis (CrA) are on average smaller than disks observed in Lupus, Taurus, Chamaeleon I, or Ophiuchus.

Aims. In contrast to previous models that studied the truncation of disks at a late stage of their evolution, we investigate whether disks may already be born with systematically smaller disk sizes in more massive star-forming regions as a consequence of higher ionization rates.

Methods. Assuming various cosmic-ray ionization rates, we computed the resistivities for ambipolar diffusion and Ohmic dissipation with a chemical network, and performed 2D nonideal magnetohydrodynamical protostellar collapse simulations.

Results. A higher ionization rate leads to stronger magnetic braking, and hence to the formation of smaller disks. Accounting for recent findings that protostars act as forges of cosmic rays and considering only mild attenuation during the collapse phase, we show that a high average cosmic-ray ionization rate in star-forming regions such as the ONC or CrA can explain the detection of smaller disks in these regions.

Conclusions. Our results show that on average, a higher ionization rate leads to the formation of smaller disks. Smaller disks in regions of similar age can therefore be the consequence of different levels of ionization, and may not exclusively be caused by disk truncation through external photoevaporation. We strongly encourage observations that allow measuring the cosmic-ray ionization degrees in different star-forming regions to test our hypothesis.
Active red giants: Close binaries versus single rapid rotators
Authors: Gaulme Patrick , Jackiewicz Jason , Spada Federico , Chojnowski Drew , Mosser Benoît , McKeever Jean , Hedlund Anne , Vrard Mathieu , Benbakoura Mansour , Damiani Cilia
Published: June 2020

Oscillating red-giant stars have provided a wealth of asteroseismic information regarding their interiors and evolutionary states, which enables detailed studies of the Milky Way. The objective of this work is to determine what fraction of red-giant stars shows photometric rotational modulation, and understand its origin. One of the underlying questions is the role of close binarity in this population, which relies on the fact that red giants in short-period binary systems (less than 150 days or so) have been observed to display strong rotational modulation. We selected a sample of about 4500 relatively bright red giants observed by Kepler, and show that about 370 of them (∼8%) display rotational modulation. Almost all have oscillation amplitudes below the median of the sample, while 30 of them are not oscillating at all. Of the 85 of these red giants with rotational modulation chosen for follow-up radial-velocity observation and analysis, 34 show clear evidence of spectroscopic binarity. Surprisingly, 26 of the 30 nonoscillators are in this group of binaries. On the contrary, about 85% of the active red giants with detectable oscillations are not part of close binaries. With the help of the stellar masses and evolutionary states computed from the oscillation properties, we shed light on the origin of their activity. It appears that low-mass red-giant branch stars tend to be magnetically inactive, while intermediate-mass ones tend to be highly active. The opposite trends are true for helium-core burning (red clump) stars, whereby the lower-mass clump stars are comparatively more active and the higher-mass ones are less active. In other words, we find that low-mass red-giant branch stars gain angular momentum as they evolve to clump stars, while higher-mass ones lose angular momentum. The trend observed with low-mass stars leads to possible scenarios of planet engulfment or other merging events during the shell-burning phase. Regarding intermediate-mass stars, the rotation periods that we measured are long with respect to theoretical expectations reported in the literature, which reinforces the existence of an unidentified sink of angular momentum after the main sequence. This article establishes strong links between rotational modulation, tidal interactions, (surface) magnetic fields, and oscillation suppression. There is a wealth of physics to be studied in these targets that is not available in the Sun.
Longitudinal drift of Tayler instability eigenmodes as a possible explanation for super-slowly rotating Ap stars
Authors: Kitchatinov L. L. , Potravnov I. S. , Nepomnyashchikh A. A.
Published: June 2020

Context. Rotation periods inferred from the magnetic variability of some Ap stars are incredibly long, exceeding ten years in some cases. An explanation for such slow rotation is lacking.

Aims. This paper attempts to provide an explanation of the super-slow rotation of the magnetic and thermal patterns of Ap stars in terms of the longitudinal drift of the unstable disturbances of the kink-type (Tayler) instability of their internal magnetic field.

Methods. The rates of drift and growth were computed for eigenmodes of Tayler instability using stellar parameters estimated from a structure model of an A star. The computations refer to the toroidal background magnetic field of varied strength.

Results. The non-axisymmetric unstable disturbances drift in a counter-rotational direction in the co-rotating reference frame. The drift rate increases with the strength of the background field. For a field strength exceeding the (equipartition) value of equal Alfven and rotational velocities, the drift rate approaches the proper rotation rate of a star. The eigenmodes in an inertial frame show very slow rotation in this case. Patterns of magnetic and thermal disturbances of the slowly rotating eigenmodes are also computed.

Conclusions. The counter-rotational drift of Tayler instability eigenmodes is a possible explanation for the observed phenomenon of super-slowly rotating Ap stars.
First observation of the magnetic dipole CO2absorption band at 3.3μm in the atmosphere of Mars by the ExoMars Trace Gas Orbiter ACS instrument
Authors: Trokhimovskiy A. , Perevalov V. , Korablev O. , Fedorova A. A. , Olsen K. S. , Bertaux J.-L. , Patrakeev A. , Shakun A. , Montmessin F. , Lefèvre F. , Lukashevskaya A.
Published: June 2020

The atmosphere of Mars is dominated by CO2, making it a natural laboratory for studying CO2spectroscopy. The Atmospheric Chemistry Suite (ACS) on board the ExoMars Trace Gas Orbiter uses solar occultation geometry to search for minor atmospheric species. During the first year of ACS observations, the attention was focused on the spectral range covering the methaneν3absorption band, 2900–3300 cm−1, which has previously been observed on Mars. No methane was detected by ACS; instead, an improvement of the data processing has led to the identification of 30 weak absorption lines that were missing from spectroscopic databases. Periodic series of absorptions up to ~1.6% deep are observed systematically around the position of the methaneQ-branch when the line of sight penetrates below 20 km (creating an optical path length of 300–400 km, with an effective pressure of a few millibar). The observed frequencies of the discovered lines match theoretically computed positions of theP-,Q-, andR-branches of the magnetic dipole and electric quadrupole 01111-00001 (ν2+ν3) absorption bands of the main CO2isotopologue; neither band has been measured or computed before. The relative depths of the observed spectral features support the magnetic dipole origin of the band. The contribution of the electric quadrupole absorption is several times smaller. Here we report the first observational evidence of a magnetic dipole CO2absorption.
Briefing des patients simulés en cinq étapes : effets perçus sur la préparation à la pratique simulée. Données d’un projet pilote
Authors: Burnier Isabelle , Fotsing Salomon , Bouchard-Lamothe Diane , Amrani Selya
Published: June 2020

Problématique :La formation des patients simulés (PS) est nécessaire pour répondre aux critères d’authenticité de la simulation. Dans le cadre de cliniques simulées, nous avons mis en place un nouveau format de briefing des PS, créé à partir d’un modèle de formation issu des arts du théâtre, combiné au briefing habituel du monde de la simulation.Objectif :Décrire les effets perçus du briefing en cinq étapes sur la préparation des PS à la pratique simulée.Méthodes :Étude qualitative et descriptive. Dix-sept PS ont répondu à un questionnaire en ligne. L’analyse inductive des données a été effectuée par trois chercheurs.Résultats :Les PS perçoivent une meilleure compréhension du scénario, une amélioration de leurs habiletés d’interprétation et de mémorisation ainsi qu’un renforcement de leur sentiment d’appartenance.Conclusion :Le briefing en cinq étapes répond au besoin d’avoir une formation courte, ponctuelle, ciblée sur le cas et propice à un encadrement sûr des PS. Il est complémentaire des formations longues et thématiques, offertes périodiquement. Une évaluation des effets observables de ce briefing sur la performance réelle des PS devrait être envisagée.
Die Addison-Krise im Notarztdienst oder „der Wolf im Schafspelz“
Authors: Köser Andrea , Gruenewald Matthias , Schulte Dominik , Reifferscheid Florian
Published: June 2020

Endokrinologische Erkrankungen begegnen einem in der Notfallmedizin insgesamt selten, noch seltener kommt es vor, dass man mit einem lebensbedrohlichen endokrinologischen Notfall konfrontiert wird. Da dieser häufig mit unspezifischen Allgemeinsymptomen einhergeht und oft als solcher verkannt wird, soll dieser Beitrag auf dieses Krankheitsbild aufmerksam machen, sensibilisieren und ein Konzept zum präklinischen Umgang vorstellen.
An Uncommon Case of Isolated Superior Rectus Palsy
Authors: Mendonca Teena Mariet , K. Suprasanna , Rodrigues Gladys R. , Pai Shobha G.
Published: June 2020

Head injury associated with orbital trauma is commonly encountered in day-to-day practice. We report a rare case of orbital trauma resulting in isolated orbital “roof blow” in fracture in a 14-year-old child. The patient presented to us with diplopia and limitation of elevation of right eye after orbital trauma. Computed tomography of the orbits (2 mm sections) did not reveal fracture of the orbital floor. However, there was orbital roof “blow in” fracture with fracture fragment impingement on the superior rectus muscle. Patient was treated conservatively and spontaneous recovery of ocular motility was noted after a month.
Robust waveguiding in substrate-integrated topological photonic crystals
Authors: Chen Qiaolu , Zhang Li , Xu Su , Wang Zuojia , Li Erping , Yang Yihao , Chen Hongsheng
Published: June 2020

Recent development of topological photonics has enabled photonic energy flow robust against disorders. On the other hand, waveguiding in substrate-integrated planar platforms is significant for microwave and mm-wave technology. Here, we propose substrate-integrated topological photonic crystals (PhCs) that support robust pseudospin-dependent edge states. We verify the robustness of pseudospin-dependent electromagnetic-wave (EM-wave) energy transport through sharply twisted corners, random defects, or a channel intersection both numerically and experimentally at microwave frequencies. The present topological PhCs with planar forms, small thicknesses, and excellent electrical shielding pave the way toward manipulation of EM topological pseudospins in an integrated platform.
A torque type full tensor gravity gradiometer based on a flexure-strip suspension
Authors: Zhang T. X. , Bai Y. Z. , Hong W. , Ma Y. , Qu S. B. , Yu L. H. , Wu S. C. , Zhou Z. B.
Published: June 2020

Full tensor gravity gradiometers based on accelerometer pair combination are widely employed in earth resource explorations using gravity gradient measurements. However, the extremely high requirements of accelerometer dynamic range and the scale factor consistency of accelerometer pairs are the two main limitations to further improve their performances. In order to overcome these two extreme challenges, the torque type gravity gradiometer based on the Etövös torsion balance pendulum is re-considered. In this paper, an improved torque type full tensor gravity gradiometer with a flexure-strip suspension is proposed, which balances the mechanical sensitivity and the response time. The proposed gradiometer can be used to measure the full tensor gravity gradient by observing angle variations at three azimuths. The principle and feasibility of the torque type full tensor gravity gradiometer based on a flexure-strip suspension are introduced, and the main noise sources including mechanical thermal noise, position sensing noise, and readout noise are analyzed. A prototype gravity gradiometer with a designed resolution of 2 E/Hz1/2 at 0.1 Hz is constructed (1 E = 10−9/s2), and the experimental results indicate that its resolution comes to 3 E/Hz1/2 at 0.1 Hz, which is mainly limited by the seismic noise. This type of gravity gradiometer can be further improved due to its high potential resolution and independence of matching combination requirement, which allows it to be applied in next generation gravity resource exploration.
Plasmon excitation in hydrogenated silicene nanostructures
Authors: Yin Hai-Feng
Published: June 2020

The impacts of the hydrogenation method and hydrogenation concentration on the plasmon excitations in hydrogenated silicene nanostructures are studied by the time-dependent density functional theory. Chair and Z-line conformations of the hydrogenated silicene nanostructure are mainly considered. When the whole silicene nanostructure is hydrogenated, because the delocalized π electrons form sp3 hybrid orbitals, the low energy plasmon resonance mode disappears. Compared with the hydrogenation that occurred in the middle area of nanostructure, when the hydrogenation occurred in the boundary area, the resonance intensity of the low-energy plasmon decreases greatly. In the high energy region, hydrogenation methods have important effects on plasmon excitation. For the chair-conformation hydrogenated silicene nanostructure, compared with pure silicene nanostructures, the band of high energy plasmon resonance spreads toward the low energy end. However, for the Z-line conformation hydrogenated silicene nanostructure, both the resonance band and the main absorption peak of the high energy plasmon have a blue shift. Moreover, the shape of the resonance band of high energy plasmon is different for hydrogenated silicene nanostructures of different conformations.
TeraChem: Accelerating electronic structure and ab initio molecular dynamics with graphical processing units
Authors: Seritan Stefan , Bannwarth Christoph , Fales B. Scott , Hohenstein Edward G. , Kokkila-Schumacher Sara I. L. , Luehr Nathan , Snyder James W. , Song Chenchen , Titov Alexey V. , Ufimtsev Ivan S. , Martínez Todd J.
Published: June 2020

Developed over the past decade, TeraChem is an electronic structure and ab initio molecular dynamics software package designed from the ground up to leverage graphics processing units (GPUs) to perform large-scale ground and excited state quantum chemistry calculations in the gas and the condensed phase. TeraChem’s speed stems from the reformulation of conventional electronic structure theories in terms of a set of individually optimized high-performance electronic structure operations (e.g., Coulomb and exchange matrix builds, one- and two-particle density matrix builds) and rank-reduction techniques (e.g., tensor hypercontraction). Recent efforts have encapsulated these core operations and provided language-agnostic interfaces. This greatly increases the accessibility and flexibility of TeraChem as a platform to develop new electronic structure methods on GPUs and provides clear optimization targets for emerging parallel computing architectures.
Plume accumulation effect and interaction of plumes induced by irradiation of a copper target with a burst of nanosecond laser pulses near the ionization threshold
Authors: Ranjbar Omid A. , Lin Zhibin , Volkov Alexey N.
Published: June 2020

The interaction between plumes induced by irradiation of a copper target in argon background gas with a burst of nanosecond laser pulses is studied numerically. The two-dimensional (2D) simulations are performed based on a model that includes a thermal model of the irradiated target and a kinetic model of plume expansion. The latter is implemented in the form of the direct simulation Monte Carlo method, where the equilibrium ionization and absorption of laser radiation are considered. For the laser spot diameter varying from 20 μm to 200 μm, the 2D plume structure is found to be different from the structure predicted by a one-dimensional model. The simulations reveal a strong plume accumulation effect when the plumes generated by preceding pulses in a burst change the conditions of propagation for plumes induced by subsequent pulses. The inter-plume interaction can result in merging shock waves induced by individual pulses and formation of a single plume. The degree of plume accumulation depends on the inter-pulse separation, laser spot diameter, background gas pressure, and number of pulses. When the irradiation conditions for a single pulse are below the ionization threshold, the conditions of plasma ignition can be reached by increasing the number of laser pulses due to the plume accumulation effect. This results in plasma shielding and reduction of the effectiveness of material removal by the subsequent pulses in the burst. The plume accumulation effect, thus, determines the optimum number of pulses in the burst in applications of laser ablation for material removal.
Tunable third harmonic generation in the vacuum ultraviolet region using dielectric nanomembranes
Authors: Konishi Kuniaki , Akai Daisuke , Mita Yoshio , Ishida Makoto , Yumoto Junji , Kuwata-Gonokami Makoto
Published: June 2020

Tunable coherent light sources operating in the vacuum ultraviolet (VUV) region in the 100–200-nm (6–12 eV) wavelength range have important spectroscopic applications in many research fields, including time-resolved angle-resolved photoemission spectroscopy. Recent advances in laser technology have enabled the upconversion of visible femtosecond lasers to the vacuum and extreme ultraviolet regions. However, the complexity of their experimental setups and the scarcity of bulk nonlinear crystals for VUV generation have hampered its widespread use. Here, we propose the use of a free-standing dielectric nanomembrane as a simple and practical method for tunable VUV generation. We demonstrate that third harmonic VUV light is generated with sufficient intensity for spectroscopic applications from commercially available SiO2 nanomembranes of submicron thicknesses under excitation with visible femtosecond laser pulses. The submicron thickness of the nanomembranes is optimal for maximizing VUV generation efficiency and prevents self-phase modulation and spectral broadening of the fundamental beam. The observed VUV photons are up to 107 photons per pulse at 157 nm with a 1-kHz repetition rate, corresponding to a conversion efficiency of 10−6. Moreover, the central VUV wavelength can be tuned in the 146–190-nm wavelength range by changing the fundamental wavelength. We also explore material and thickness dependence with experiments and calculations. The presented results suggest that dielectric nanomembranes can be used as practical nonlinear media for VUV spectroscopic applications.