bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of technology for increasing well completion during drilling in the abnormal reservoir pressures intervals
Authors: Redrovan Pierre , Kuchin Vyacheslav , Dvoynikov Mikhail
Published: November 2020

Oil and gas resource production volumes in Russian fields are more confined to the development of areas discovered in the 70s-80s. According to their operation and development level, a depletion of reserves and a decrease in reservoir pressure are observed. The long time for development contributes to the complication of well construction conditions in these fields, especially in the matter of ensuring the reliability of separation of discovered reservoirs. The analysis of drilling and completion materials for fields in North Siberia and the Artic region showed that the absorption value of cement slurries during well attachment has increased, as well as the presence of inter-reservoir flows.
Die Insula
Authors: Corts Magga
Published: November 2020

Die Insula ist also Teil der Großhirnrinde und liegt im tiefgefalteten Sulcus lateralis. Sie ist ein sensorisches Areal mit vielen Aufgaben.
Wenn der Körper Schatten auf die Seele wirft
Authors: Pasch Anja
Published: November 2020

Die Somatopsychologie beschreibt den Einfluss körperlicher Erkrankungen auf die Psyche einschließlich somatisch bedingter psychischer Störungen wie Depressionen, Ängsten und Impulsivität. Veränderungen von Persönlichkeit und Stimmung werden häufig psychopathologisch diagnostiziert und behandelt, auch wenn sie tatsächlich sekundär im Rahmen einer körperlichen Erkrankung auftreten. Zu den häufigen, zunächst oft unerkannten, organischen Ursachen psychischer Störungen zählen chronische Entzündungen, Allergien, Hormonschwankungen und neurologische Prozesse wie Chorea Huntington oder Hydrocephalus.
Einmal Erschöpfung und zurück
Authors: Grappendorf Doris
Published: November 2020

Das Chronische Erschöpfungssyndrom gilt bis heute als unheilbar. Die Autorin des Beitrags berichtet von einer erfolgreichen Selbstheilung auf Basis eines eigens erdachten Behandlungskonzepts. Als Ursache der Erkrankungen werden verschiedene Faktoren diskutiert. Der geschilderte Fall legt nahe, dass schwerwiegende Vergiftungserscheinungen im Sinne einer Verschlackung eine Ursache sein können. Das vorgestellte Behandlungskonzept kombiniert eine tiefgreifende und langwierige Ernährungsumstellung mit einem sorgfältigen Energiemanagement nach der 50 %-Methode.
Heilpraktikerausbildung steuerlich absetzen
Authors: Sell Michael
Published: November 2020

Kosten der Heilpraktikerausbildung können ohne Einschränkungen geltend gemacht werden, wenn der Kandidat bereits eine abgeschlossene Berufsausbildung vorweisen kann. Ist die Heilpraktikerausbildung eine Erstausbildung, sind diese Kosten nur als Sonderausgaben begrenzt abzugsfähig. Als Ausbildungskosten sind alle Kosten abzugsfähig, die durch die Ausbildung veranlasst sind. Die Aufwendungen sind nur in dem Jahr abzugsfähig, in dem sie bezahlt wurden.
Die Hunderute – Grundlagen der osteopathischen und physiotherapeutischen Therapie
Authors: Röhrmann Nicole , Louis Anne Lisa , Raabe Isabel
Published: November 2020

Die Rute des Hundes ist auf verschiedene Weise ein Signalgeber und dient nicht nur der Kommunikation mit Artgenossen, sondern auch mit Tierärzten und Therapeuten. Durch ihre enge Beziehung zu Wirbelsäule und Becken, aber auch zum Nervensystem und dem umliegenden Weichteilgewebe gibt sie Aufschluss über innere und äußere Spannungen. Dies kann in der Physiotherapie und Osteopathie sowohl diagnostisch als auch therapeutisch hilfreich sein.
Alle Jahre wieder – Geräuschängsten von Hund und Katze wirksam begegnen
Authors: Zurr Daniela , Brendieck-Worm Cäcilia , Kübler Heidi
Published: November 2020

Geräuschängste bei Hund und Katze stellen ein relativ häufiges, aber meist wenig beachtetes Problem dar. Oftmals zwingen erst Ausnahmesituationen, wie das Feuerwerk an Silvester, die Tierhalter zum konkreten Handeln. Unmittelbar vor dem Ereignis bleibt dem behandelnden Tierarzt dann nur noch ein Notfallplan, der sich aus Maßnahmen zur Abschirmung des Tieres, sozialer Unterstützung und sensorischem Feedback zusammensetzt – gegebenenfalls unterstützt durch die Gabe von Psychopharmaka. Regulationsmedizinische Ansätze, wie Phytotherapie oder Bach-Blüten-Therapie, brauchen etwas mehr Zeit (Beginn mindestens 1 Woche vor Silvester), zeigen dann aber gute Wirksamkeit ohne unerwünschte Nebenwirkungen oder unvorhersehbare Reaktionen. Besonders effektiv ist ihr Einsatz im Rahmen einer Verhaltenstherapie bei Tieren, die generell ängstlich sind und auch auf andere Auslöser als Geräusche reagieren.
Establishing key research questions for the implementation of artificial intelligence in colonoscopy: a modified Delphi method
Authors: Ahmad Omer F. , Mori Yuichi , Misawa Masashi , Kudo Shin-ei , Anderson John T. , Bernal Jorge , Berzin Tyler M. , Bisschops Raf , Byrne Michael F. , Chen Peng-Jen , East James E. , Eelbode Tom , Elson Daniel S. , Gurudu Suryakanth R. , Histace Aymeric , Karnes William E. , Repici Alessandro , Singh Rajvinder , Valdastri Pietro , Wallace Michael B. , Wang Pu , Stoyanov Danail , Lovat Laurence B.
Published: November 2020

Background Artificial intelligence (AI) research in colonoscopy is progressing rapidly but widespread clinical implementation is not yet a reality. We aimed to identify the top implementation research priorities.

Methods An established modified Delphi approach for research priority setting was used. Fifteen international experts, including endoscopists and translational computer scientists/engineers, from nine countries participated in an online survey over 9 months. Questions related to AI implementation in colonoscopy were generated as a long-list in the first round, and then scored in two subsequent rounds to identify the top 10 research questions.

Results The top 10 ranked questions were categorized into five themes. Theme 1: clinical trial design/end points (4 questions), related to optimum trial designs for polyp detection and characterization, determining the optimal end points for evaluation of AI, and demonstrating impact on interval cancer rates. Theme 2: technological developments (3 questions), including improving detection of more challenging and advanced lesions, reduction of false-positive rates, and minimizing latency. Theme 3: clinical adoption/integration (1 question), concerning the effective combination of detection and characterization into one workflow. Theme 4: data access/annotation (1 question), concerning more efficient or automated data annotation methods to reduce the burden on human experts. Theme 5: regulatory approval (1 question), related to making regulatory approval processes more efficient.

Conclusions This is the first reported international research priority setting exercise for AI in colonoscopy. The study findings should be used as a framework to guide future research with key stakeholders to accelerate the clinical implementation of AI in endoscopy.
Transition-Metal-Free Functionalization of Saturated and Unsaturated Amines to Bioactive Alkaloids Mediated by Sodium Chlorite
Authors: Sartillo-Piscil Fernando , Romero-Ibañez Julio , Fuentes Lilia
Published: November 2020

New approaches to the synthesis of alkaloids through the straightforward functionalization of C(sp3)–H and C(sp2)=C(sp2) bonds of simple five- and six-membered-ring N-heterocycles are highlighted. The direct functionalization of pre-existing N-heterocycles to advanced alkaloids intermediates is a chemical operation that commonly requires the intervention of transition or precious metals. Regardless the inherent unwanted waste production, the high economical cost of many transition-metal catalysts limits their use globally. Here, we account our efforts directed toward the synthesis of bioactive alkaloids under an economic and ecological fashion by using NaClO2 as the key activating or oxidizing reagent that substitutes the use of transition-metal catalysts. While undesired metal wastes are collected during the extraction process of a transition-metal-catalyzed reaction, innocuous NaCl is the commonly product waste when NaClO2 is employed in our chemical transformations. Beginning with the synthesis of 2,3-epoxyamides from allyl amines, we concluded with the functionalization of multiple and remote C(sp3)–H and C(sp3)–C(sp3) bonds in piperidine rings that enabled the preparation of important bioactive alkaloids. For the latter functionalization, a precise amount of co-oxidant reagent (NaOCl) and radical 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) were needed.

1 Introduction

2 Direct Chemical Method for Preparing 2,3-Epoxyamides

3 Dual C(sp3)–H Oxidation of Cyclic Amines to 3‑Alkoxyamine Lac­tams

4 Electrochemical Deamination of 3-Alkoxyamine Lactams

5 Direct C–H Oxidation of Piperazines and Morpholines to 2,3-Diketopiperazines and 3-Morpholinones, Respectively

6 Transition-Metal-Free Triple C–H Oxidation

7 Deconstructive Lactamization of Piperidines

8 Conclusion
Recent Developments in Heck-Type Reaction of Unactivated Alkenes and Alkyl Electrophiles
Authors: Shi Lili , Fu Junkai , Gao Shuangqiu , Chang Le , Wang Binglin
Published: November 2020

The Mizoroki–Heck reaction is considered as one of the most ingenious and widely used methods for constructing C–C bonds. This reaction mainly focuses on activated olefins (styrenes, acrylates, or vinyl ethers) and aryl/vinyl (pseudo) halides. In comparison, the studies on unactivated alkenes and alkyl electrophiles are far less due to the low reactivity, poor selectivity, as well as competitive β-H elimination. In the past years, a growing interest has thus been devoted and significant breakthroughs have been achieved in the employment of unactivated alkenes and alkyl electrophiles as the reaction components, and this type of coupling is called as Heck-type or Heck-like reaction, which distinguishes from the traditional Heck reaction. Herein, we give a brief summary on Heck-type reaction between unactivated alkenes and alkyl electrophlies, covering its initial work, recent advancements, and mechanistic discussions.

1 Introduction

2 Intramolecular Heck-Type Reaction of Unactivated Alkenes and Alkyl Electrophiles

2.1 Cobalt-Catalyzed Intramolecular Heck-Type Reaction

2.2 Palladium-Catalyzed Intramolecular Heck-Type Reaction

2.3 Nickel-Catalyzed Intramolecular Heck-Type Reaction

2.4 Photocatalysis and Multimetallic Protocol for Intramolecular Heck-Type Reaction

3 Intermolecular Heck-Type Reaction of Unactivated Alkenes and Alkyl Electrophiles

3.1 Electrophilic Trifluoromethylating Reagent as Reaction Partners

3.2 Alkyl Electrophiles as Reaction Partners

4 Oxidative Heck-Type Reaction of Unactivated Alkenes and Alkyl Radicals

5 Conclusions and Outlook
Birth Tourism Is Associated with Fewer Neonatal Intensive Care Unit Admissions: A Healthy Migrant Effect?
Authors: Lim Jina , Sun Wang-Dar , Zhang Lishi , Mikhael Michel
Published: November 2020

Objective This work aimed to study perinatal, maternal, and neonatal characteristics of birth tourism (BT) mother–baby dyads and the rate of neonatal intensive care unit (NICU) admissions of BT infants.

Study Design Retrospective study at a regional perinatal center comparing BT mother–baby dyads to all dyads. BT infants admitted to the NICU were compared with a randomly selected group of infants admitted to the NICU during the same time period.

Results A total of 1,755 BT dyads were identified over 4 years. BT mothers were older (32 vs. 28 years, p < 0.0001), more likely to carry multiples (5.5 vs. 1.4%, p < 0.0001), deliver via cesarean section (40 vs. 34%, p < 0.0001), and require postpartum intensive care (0.6 vs. 0.1%, p < 0.0001). BT infants had significantly fewer NICU admissions 96 (5.5%) versus 3,213 (11.3%; p < 0.0001). There were no statistically significant differences in NICU course and outcome between BT and non-BT control infants.

Conclusion Birth tourism is associated with unique determinants of health. In our study, there were fewer NICU admissions, potentially explained by the healthy migrant effect.

Key Points
Pathogenesis of Congenital Malformations: Possible Role of Oxidative Stress
Authors: Impellizzeri Pietro , Nascimben Francesca , Di Fabrizio Donatella , Antonuccio Pietro , Antonelli Enrica , Peri Flora Maria , Calabrese Ugo , Arena Salvatore , Romeo Carmelo
Published: November 2020

Objective Congenital anomalies are important causes of morbidity and mortality in children. Oxidative stress (OS) is involved in the physiopathology of pregnancy-related congenital malformations. This review summarizes the role of OS in the pathogenesis of congenital malformations; in particular, its purpose is to describe how OS influences the development of heart congenital malformations, oesophageal atresia, biliary atresia, diaphragmatic hernia, and autosomal dominant polycystic kidney disease.

Study Design Systematic review of previous studies about the role of OS in pregnancy and its possible effects in developing of congenital malformations. One electronic database (PubMed) was searched and reference lists were checked.

Results An imbalance between the production of reactive oxygen species (ROS) and antioxidant defense can occur early in pregnancy and continue in the postnatal life, producing OS. It may destroy the signaling pathways needed for a correct embryogenesis leading to birth defects. In fact, cell functions, especially during embryogenesis, needs specific signaling pathways to regulate the development. These pathways are sensitive to both endogenous and exogenous factors; therefore, they can produce structural alterations of the developing fetus.

Conclusion Because OS plays a significant role in pathogenesis of congenital malformations, studies should be developed in order to better define their OS mechanisms and the beneficial effects of supplemental therapeutic strategies.

Key Points
Direct and indirect excitons in two-dimensional covalent organic
frameworks
Authors: Sun Shan , Ma Hui-zhong , Zhang Xiao , Ma Yu-chen
Published: November 2020

Highly luminescent bulk two-dimensional covalent organic frameworks (COFs) attract much attention recently. Origin of their luminescence and their large Stokes shift is an open question. After first-principles calculations on two kinds of COFs using the GW method and Bethe-Salpeter equation, we find that monolayer COF has a direct band gap, while bulk COF is an indirect band-gap material. The calculated optical gap and optical absorption spectrum for the direct excitons of bulk COF agree with the experiment. However, the calculated energy of the indirect exciton, in which the photoelectron and the hole locate at the conduction band minimum and the valence band maximum of bulk COF respectively, is too low compared to the fluorescence spectrum in experiment. This may exclude the possible assistance of phonons in the luminescence of bulk COF. Luminescence of bulk COF might result from exciton recombination at the defects sites. The indirect band-gap character of bulk COF originates from its AA-stacked conformation. If the conformation is changed to the AB-stacked one, the band gap of COF becomes direct which may enhance the luminescence.
Hydroxyl group modifies aggregation behavior of a non-ionic hydro-fluorocarbon hybrid surfactant by disrupting interfacial water
Authors: Peng Ying-ying , Liao Yi-fan , Gan Wei , Tong Qing-xiao , Yuan Qun-hui
Published: November 2020

Two non-ionic hydro-fluorocarbon hybrid surfactants with and without hydroxyl groups were synthesized and compared. They exhibited good thermal stability and superior surface activity. It was observed that the hydroxyl group had a profound effect on modifying the surface tension of their solutions and the morphology of the formed micelles. This effect may be attributed to the rearranging of the alkane group from above the air/aqueous surface to below it and the disrupting of the interfacial water structure induced by the hydroxyl groups. This work provides a strategy to weaken the immiscibility between hydrocarbon and fluorocarbon chains by modifying their orientational structure at the interface, thus it is helpful for the design of surfactants with varied interfacial properties.
Fractal analysis of recurrence networks constructed from the two-dimensional fractional Brownian motions
Authors: Liu Jin-Long , Yu Zu-Guo , Leung Yee , Fung Tung , Zhou Yu
Published: November 2020

In this study, we focus on the fractal property of recurrence networks constructed from the two-dimensional fractional Brownian motion (2D fBm), i.e., the inter-system recurrence network, the joint recurrence network, the cross-joint recurrence network, and the multidimensional recurrence network, which are the variants of classic recurrence networks extended for multiple time series. Generally, the fractal dimension of these recurrence networks can only be estimated numerically. The numerical analysis identifies the existence of fractality in these constructed recurrence networks. Furthermore, it is found that the numerically estimated fractal dimension of these networks can be connected to the theoretical fractal dimension of the 2D fBm graphs, because both fractal dimensions are piecewisely associated with the Hurst exponent H in a highly similar pattern, i.e., a linear decrease (if H varies from 0 to 0.5) followed by an inversely proportional-like decay (if H changes from 0.5 to 1). Although their fractal dimensions are not exactly identical, their difference can actually be deciphered by one single parameter with the value around 1. Therefore, it can be concluded that these recurrence networks constructed from the 2D fBms must inherit some fractal properties of its associated 2D fBms with respect to the fBm graphs.
Phase portrait for high fidelity feature extraction and classification: A surrogate approach
Authors: Renjini A. , Raj Vimal , Swapna M. S. , Sreejyothi S. , Sankararaman S.
Published: November 2020

This paper proposes a novel surrogate method of classification of breath sound signals for auscultation through the principal component analysis (PCA), extracting the features of a phase portrait. The nonlinear parameters of the phase portrait like the Lyapunov exponent, the sample entropy, the fractal dimension, and the Hurst exponent help in understanding the degree of complexity arising due to the turbulence of air molecules in the airways of the lungs. Thirty-nine breath sound signals of bronchial breath (BB) and pleural rub (PR) are studied through spectral, fractal, and phase portrait analyses. The fast Fourier transform and wavelet analyses show a lesser number of high-intense, low-frequency components in PR, unlike BB. The fractal dimension and sample entropy values for PR are, respectively, 1.772 and 1.041, while those for BB are 1.801 and 1.331, respectively. This study reveals that the BB signal is more complex and random, as evidenced by the fractal dimension and sample entropy values. The signals are classified by PCA based on the features extracted from the power spectral density (PSD) data and the features of the phase portrait. The PCA based on the features of the phase portrait considers the temporal correlation of the signal amplitudes and that based on the PSD data considers only the signal amplitudes, suggesting that the former method is better than the latter as it reflects the multidimensional aspects of the signal. This appears in the PCA-based classification as 89.6% for BB, a higher variance than the 80.5% for the PR signal, suggesting the higher fidelity of the phase portrait-based classification.
Transient magnetic field diffusion considerations relevant to magnetically assisted indirect drive inertial confinement fusion
Authors: Moody J. D. , Johnson A. , Javedani J. , Carroll E. , Fry J. , Kozioziemski B. , Kucheyev S. O. , Logan B. G. , Pollock B. B. , Sio H. , Strozzi D. , Stygar W. A. , Tang V. , Winters S.
Published: November 2020

Application of a magnetic field to an indirect drive inertial confinement fusion target requires diffusion of the field through the high-Z and electrically conducting Hohlraum. The onset of the external field generates eddy currents in the Hohlraum wall that result in (1) a reduction of the peak field at the capsule, (2) heating of the Hohlraum wall through Ohmic dissipation, and (3) wall movement due to the inward force from the eddy current interacting with the field. Heating of the wall causes an increase in blackbody radiation which can preheat the capsule and frozen deuterium–tritium fuel, while wall motion leads to potential misalignment of the lasers at the Hohlraum wall. Limiting these detrimental effects sets requirements on the tolerable magnitude of each effect. We present a nonlinear model for B-field diffusion through an infinitely long thin-walled cylinder with a temperature dependent resistivity, to show that a 15 μm thick wall of pure gold fails to meet these requirements. A new Hohlraum material made from an alloy of Au and Ta has a measured resistivity of ≥60 times that of Au and is shown with the nonlinear model to meet the requirements for magnetization. We compare the nonlinear model to simulations of the actual Hohlraum target using a finite element code which includes temperature-dependent Hohlraum resistivity.
The Fermi–Löwdin self-interaction correction for ionization energies of organic molecules
Authors: Adhikari Santosh , Santra Biswajit , Ruan Shiqi , Bhattarai Puskar , Nepal Niraj K. , Jackson Koblar A. , Ruzsinszky Adrienn
Published: November 2020

(Semi)-local density functional approximations (DFAs) suffer from self-interaction error (SIE). When the first ionization energy (IE) is computed as the negative of the highest-occupied orbital (HO) eigenvalue, DFAs notoriously underestimate them compared to quasi-particle calculations. The inaccuracy for the HO is attributed to SIE inherent in DFAs. We assessed the IE based on Perdew–Zunger self-interaction correction on 14 small to moderate-sized organic molecules relevant in organic electronics and polymer donor materials. Although self-interaction corrected DFAs were found to significantly improve the IE relative to the uncorrected DFAs, they overestimate. However, when the self-interaction correction is interiorly scaled using a function of the iso-orbital indicator zσ, only the regions where SIE is significant get a correction. We discuss these approaches and show how these methods significantly improve the description of the HO eigenvalue for the organic molecules.
Influence of asymmetric degree on the characteristics of a homogeneous barrier discharge excited by an asymmetric sine
Authors: Ren Chenhua , He Xingran , Jia Pengying , Wu Kaiyue , Li Xuechen
Published: November 2020

An atmospheric pressure dielectric barrier discharge driven by an asymmetric sinusoidal voltage has been investigated numerically with a one-dimensional fluid model. Results indicate that, as a controlling parameter, the asymmetric degree (Das) of applied voltage can significantly affect discharge characteristics. With an increasing absolute value of Das [abs(Das)], the maximal current density remains almost constant at low abs(Das) and increases significantly at high abs(Das), while the phase of the discharge with the maximal current gradually approaches toward 0° of the applied voltage. Meanwhile, discharge transits from a Townsend mode to a glow mode. Moreover, the electron density (ne) increases more than three orders of magnitude during this process, hence it is viable to manipulate ne by adjusting Das. Besides, N4+ is the predominant positively charged species with abs(Das) lower than about 60%. Out of this range, He2+ takes the place of N4+, becoming the predominant positively charged species. Further investigations reveal that in the primary discharge, direct ionization takes an important role with high abs(Das), while Penning ionization becomes important with low abs(Das). Moreover, dominant reactions for electron production are clarified. These results are of great significance in the manipulation of ne for a homogeneous barrier discharge.
Photodissociation spectroscopy of N2O+ in the ion storage ring RICE
Authors: Igosawa R. , Hirota A. , Kimura N. , Kuma S. , Chartkunchand K. C. , Mishra P. M. , Lindley M. , Yamaguchi T. , Nakano Y. , Azuma T.
Published: November 2020

The A2Σ+–X2Π electronic transition of the nitrous oxide cation, N2O+, was measured via photodissociation spectroscopy in a cryogenic electrostatic ion storage ring. Rotationally resolved spectra of the N–O stretching vibrational sequence were obtained by detecting neutral N fragments produced via N2O+ → NO+ + N predissociation channels. A new set of molecular constants was determined for the high-lying vibrational levels of the A2Σ+ state.
Surface wave characteristics of a volume source horizontally translating in a stratified fluid
Authors: Li Yuhang , Chen Ke , Wang Hongwei , You Yunxiang
Published: November 2020

The present work aims to investigate the free surface wave system of a volume source translating in a stratified fluid. In this paper, a modified model is established with linearized governing equations and the free surface condition. This modified model can describe both the internal and surface waves excited by a volume source with arbitrary density profiles. The wave characteristics that are analyzed include the half-wedge angle, crestlines, the maximum amplitude, and the apparent angle. The results show that the entire wave system is complex and composed by an infinite number of single wave modes. The different modes can be divided into surface modes (mode number n = 0) and internal modes (n ≥ 1). It is found that internal modes have many similarities to each other but are quite different from surface modes. In the subcritical area [Fr<Frn, where the Froude number is Fr=U/gL and the critical Froude number of mode n is Frn=cpn(0)/gL], the wave structure of the nth mode contains divergent and transverse waves, and the half-wedge angle of surface mode waves increases from the Kelvin-wave angle of 19°28′ to 90°, while the half-wedge angle of internal mode waves increases from 0° to 90°. In the supercritical domain (Fr ≥ Frn), there are only divergent waves, and the half-wedge angle of all mode waves decays as sin−1(Frn/Fr). The amplitude of waves is related to the velocity of the source, the location of the source, the depth of the fluid, the Brunt–Väisälä frequency, the thickness of the pycnocline, and the center location of the pycnocline. The effects of these factors have been discussed in this paper. The apparent angle, which indicates the highest peak of waves, is also discussed. The results show that the apparent angle of all mode waves scales like Fr−1 at large Froude numbers.
Exploring reactivity and product formation in N(4S) collisions with pristine and defected graphene with direct dynamics simulations
Authors: Nieman Reed , Spezia Riccardo , Jayee Bhumika , Minton Timothy K. , Hase William L. , Guo Hua
Published: November 2020

Atomic nitrogen is formed in the high-temperature shock layer of hypersonic vehicles and contributes to the ablation of their thermal protection systems (TPSs). To gain atomic-level understanding of the ablation of carbon-based TPS, collisions of hyperthermal atomic nitrogen on representative carbon surfaces have recently be investigated using molecular beams. In this work, we report direct dynamics simulations of atomic-nitrogen [N(4S)] collisions with pristine, defected, and oxidized graphene. Apart from non-reactive scattering of nitrogen atoms, various forms of nitridation of graphene were observed in our simulations. Furthermore, a number of gaseous molecules, including the experimentally observed CN molecule, have been found to desorb as a result of N-atom bombardment. These results provide a foundation for understanding the molecular beam experiment and for modeling the ablation of carbon-based TPSs and for future improvement of their properties.
Forced oscillation dynamics of surface nanobubbles
Authors: Dockar Duncan , Gibelli Livio , Borg Matthew K.
Published: November 2020

Surface nanobubbles have potential applications in the manipulation of nanoscale and biological materials, waste-water treatment, and surface cleaning. These spherically capped bubbles of gas can exist in stable diffusive equilibrium on chemically patterned or rough hydrophobic surfaces, under supersaturated conditions. Previous studies have investigated their long-term response to pressure variations, which is governed by the surrounding liquid’s local supersaturation; however, not much is known about their short-term response to rapid pressure changes, i.e., their cavitation dynamics. Here, we present molecular dynamics simulations of a surface nanobubble subjected to an external oscillating pressure field. The surface nanobubble is found to oscillate with a pinned contact line, while still retaining a mostly spherical cap shape. The amplitude–frequency response is typical of an underdamped system, with a peak amplitude near the estimated natural frequency, despite the strong viscous effects at the nanoscale. This peak is enhanced by the surface nanobubble’s high internal gas pressure, a result of the Laplace pressure. We find that accurately capturing the gas pressure, bubble volume, and pinned growth mode is important for estimating the natural frequency, and we propose a simple model for the surface nanobubble frequency response, with comparisons made to other common models for a spherical bubble, a constant contact angle surface bubble, and a bubble entrapped within a cylindrical micropore. This work reveals the initial stages of growth of cavitation nanobubbles on surfaces, common in heterogeneous nucleation, where classical models based on spherical bubble growth break down.
Infrared multiple photon dissociation spectroscopy of anionic copper formate clusters
Authors: Pascher Tobias F. , Ončák Milan , van der Linde Christian , Beyer Martin K.
Published: November 2020

We investigate the structure of copper formate and deuterated copper formate clusters using infrared multiple photon dissociation in combination with quantum chemical calculations. Symmetric and asymmetric C–O stretching vibrations along with C–H/C–D stretching vibrations were characterized. Fermi interactions between the C–H stretch and likely a C–O combination band and/or the overtone of a C–H in-plane bending motion have been confirmed by deuteration. The spectra reveal a strong dependence on the monodentate or bidentate binding motif of the formate ligands. Many minima are energetically accessible on the potential energy surface through rotation of the monodentate formate ligands into several almost isoenergetic local minima. While the C–H/C–D stretching vibration is heavily influenced by the charge distribution in the cluster, the C–O vibrations are largely unaffected. The C–H stretch region is not very diagnostic due to a variety of possible Fermi resonances, which also depend on the charge distribution at the formate ligand. Deuteration yields unperturbed spectra in the C–D stretch region and reveals characteristic shifts of the C–D stretching mode for the different binding motifs, with a strong dependence of the band position on the oxidation state of the copper center. The observed bands are compared with formate adsorbed on copper surfaces from the literature.
Revisiting the basic theory of sum-frequency generation
Authors: Shen Y. R.
Published: November 2020

The basic theory of sum-frequency generation (SFG) is revisited. A rigorous derivation showing that linear optical transmission and reflection at an interface result from the interference of the incident wave and induced radiation wave in a medium is presented. The derivation is extended to SFG in a medium with a finite interface layer to see how SFG evolves. Detailed description on interface vs bulk and electric dipole (ED) vs electric quadrupole (EQ) contribution to SFG are provided with essentially no model dependence, putting the theory of SFG on a solid ground and removing possible existing confusions. Electric-quadrupole contributions to SFG from the interface and bulk are discussed. It is seen that there is a relevant bulk EQ contribution intrinsically inseparable in measurement from the interface ED contribution but plays a major role among all EQ contributions; its importance relative to the ED part can only be judged by referring to the established reference cases.
Theoretical study of fast diffusion in carbon nanontubes
Authors: Barlow Douglas A. , Colson Fenner E.
Published: November 2020

Using a recently reported method for the statistical representation of gaseous diffusion within a cylindrical pore, we report here on an analysis of situations that describe fast diffusion within carbon nanotubes. It is proposed that if gaseous flow properties of the tube, in the highly rarefied situation, are due to there being only specular particle–wall reflections, then these particles can transit the tube via self-diffusion. On comparing this self-diffusive flux with Knudsen transport diffusion, our model predicts that enhanced diffusion is indeed possible in the carbon nanotube. Depending upon the statistical nature of the particle–wall scattering phenomenon, the enhancements are predicted be three to four times that of classical transport diffusion and, for certain conditions, the enhancement factor can be greater than 4.
Flow visualization of an N95 respirator with and without an exhalation valve using schlieren imaging and light scattering
Authors: Staymates Matthew
Published: November 2020

This work demonstrates the qualitative fluid flow characteristics of a standard N95 respirator with and without an exhalation valve. Schlieren imaging was used to compare an adult male breathing through an N95 respirator with and without a valve. The schlieren imaging technique showed the flow of warm air passing through these respirators but did not provide information about droplet penetration. For this, strategic lighting of fog droplets was used with a mannequin head to visualize the penetration of droplets through both masks. The mannequin exhaled with a realistic flow rate and velocity that matched an adult male. The penetration of fog droplets was also visualized with a custom system that seals each respirator onto the end of a flow tube. Results of these qualitative experiments show that an N95 respirator without an exhalation valve is effective at blocking most droplets from penetrating through the mask material. Results also suggest that N95 respirators with exhalation valves are not appropriate as a source control strategy for reducing the proliferation of infectious diseases that spread via respiratory droplets.
Anomalous changes in the acoustic properties and central peak behaviors of PbxBa1−xNb2O6 single crystals with x = 0.5 studied by Brillouin spectroscopy
Authors: Naqvi Furqan Ul Hassan , Ko Jae-Hyeon , Lim Ki-Soo
Published: November 2020

The acoustic properties of tetragonal PbxBa1−xNb2O6 (PBN-x) single crystals with x = 0.5 were studied by Brillouin spectroscopy over a wide temperature range from room temperature to 600 °C. Anomalous changes in the Brillouin frequency shift and the half width of acoustic waves were observed at ∼350 °C that corresponds to the ferroelectric–paraelectric phase transition temperature of PBN-0.50. The longitudinal sound velocity and its associated elastic constant (C33) showed substantial softening in the paraelectric phase when the phonon propagated along the polar c axis, while their degree of softening for the phonon along the a axis was small, revealing clear acoustic anisotropy. It was associated with the strong polarization dependence of the quasi-elastic central peak. The relaxation time derived from the central peak seemed to follow the critical slowing-down behavior indicating order–disorder nature of the phase transition. Among C44 and C66, the former displayed substantial softening in the ferroelectric phase resembling the order parameter behavior. The longitudinal sound velocity and the related acoustic damping showed significant anomalies in the ferroelectric phase of unpoled PBN-0.5, which disappeared completely under poled condition. The possible origin for these unexpected acoustic anomalies was suggested.
Therapeutics for COVID-19: established and in development
Authors: Singh Kasha P , Sasadeusz Joe , Lewin Sharon R , Audsley Jennifer
Published: November 2020

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first recognised in late 2019, with over 30 000 000 cases and over 1 000 000 deaths reported by the end of September 2020. SARS-CoV-2 infection is usually associated with fever, cough, coryza, dyspnoea, anosmia, headache and fatigue and may cause pneumonia and hypoxemia. An excessive/dysregulated inflammatory response may lead to lung damage including acute respiratory distress syndrome (ARDS), coagulopathy and other complications. Mortality amongst hospitalised patients is higher in those needing intensive care. In Australia over 27 000 cases with 882 deaths had been reported by 30 September, most in Victoria. Two therapies have proven beneficial in treatment of hospitalised patients in expedited randomised placebo-controlled trials and are now in widespread use. Dexamethasone improved survival of those requiring respiratory support and the antiviral agent remdesivir decreased time to recovery in mild-moderate disease. Remdesivir was authorised by the Australian Therapeutic Goods Administration in July 2020. Over 200 other therapeutics are being tested for COVID-19 in more than 2000 clinical trials, and many more agents are in preclinical development. We review the evidence for some of the candidates for therapy in COVID-19.
The potassium channel subunit K
v
β1 serves as a major control point for synaptic facilitation
Authors: Cho In Ha , Panzera Lauren C. , Chin Morven , Alpizar Scott A. , Olveda Genaro E. , Hill Robert A. , Hoppa Michael B.
Published: November 2020

Significance

Nerve terminals generally engage in two opposite and essential forms of synaptic plasticity (facilitation or depression) that play critical roles in learning and memory. While the molecular components of both types of terminals are similar with regards to vesicle fusion, much less is known about their molecular control of electrical signaling. Measurements of the electrical impulses (action potentials) underlying these two forms of plasticity have been difficult in small nerve terminals due to their size. In this study we deployed optical physiology measurements to overcome this size barrier. Here, we identify a unique mechanism (Kvβ1 subunit) that enables broadening of the presynaptic action potentials that selectively supports synaptic facilitation, but does not alter any other aspects of nerve terminal function.
Rerouting of ribosomal proteins into splicing in plant organelles
Authors: Wang Chuande , Fourdin Rachel , Quadrado Martine , Dargel-Graffin Céline , Tolleter Dimitri , Macherel David , Mireau Hakim
Published: November 2020

Significance

Ribosomal proteins (RPs) are essential structural components of ribosomes. In many instances, RPs are encoded in small families of genes, suggesting possible neofunctionalization for some family members. This is the case of the uL18 family of proteins that developed during plant evolution and which is composed of eight members in most Angiosperms. Our study shows that two members associate with organellar ribosomes while two other uL18-Like proteins have become intron-specific splicing factors acting in mitochondria and plastids, respectively. Our study shows that the RNA binding capacity of RPs can be diverted to create factors acting in intron splicing.
Rapid reductions and millennial-scale variability in Nordic Seas sea ice cover during abrupt glacial climate changes
Authors: Sadatzki Henrik , Maffezzoli Niccolò , Dokken Trond M. , Simon Margit H. , Berben Sarah M. P. , Fahl Kirsten , Kjær Helle A. , Spolaor Andrea , Stein Ruediger , Vallelonga Paul , Vinther Bo M. , Jansen Eystein
Published: November 2020

Significance

The last glacial period was marked by abrupt, high-amplitude Greenland warming events, known as Dansgaard–Oeschger (D-O) events, which were likely linked with Nordic Seas sea ice retreat. We reconstruct the sea ice variability during four D-O events ∼32–41 ka with unprecedented spatial representation and rigorous temporal constraints, using proxy records from two Norwegian Sea sediment cores and an East Greenland ice core. Our records reveal millennial-scale variations between extended sea ice conditions and reduced seasonal sea ice conditions, with rapid sea ice reductions at the onset of D-O events. Our findings imply that rapid sea ice reduction amplified ocean-atmosphere processes causing the abrupt D-O climate transitions, providing constraints for model simulations of abrupt climate changes and their mechanisms.
Geographies of insecure water access and the housing–water nexus in US cities
Authors: Meehan Katie , Jurjevich Jason R. , Chun Nicholas M. J. W. , Sherrill Justin
Published: November 2020

Significance

Secure water access is a fundamental human right. Our study reveals disparities in piped water access in urban areas in the United States. From 2013 to 2017, we find that an estimated 1,121,100 people (±25,500) in the United States had insecure water access, with nearly one-half (47%) located in the 50 largest metropolitan areas. Unplumbed households in cities, on balance, are more likely to be headed by people of color, earn lower incomes, live in mobile homes, rent their residence, and pay a higher share of their gross income toward housing costs. We offer clear evidence that gaps in urban water access are neither random nor accidental but underpinned by precarious housing conditions and systemic social and racialized inequality.
A climatic dipole drives short- and long-term patterns of postfire forest recovery in the western United States
Authors: Littlefield Caitlin E. , Dobrowski Solomon Z. , Abatzoglou John T. , Parks Sean A. , Davis Kimberley T.
Published: November 2020

Significance

Rising temperatures and increasing drought may compromise ecosystems’ abilities to recover from disturbance. This study reveals how recurring, large-scale patterns in drought variability have short- and long-term effects on forest recovery from wildfire in the western United States. Annual juvenile ponderosa pine recruitment in the Northern Rockies and Southwest tracks a north–south climatic dipole that emerges approximately every 4 y and renders one region anomalously dry and the other anomalously wet. Anomalously dry conditions inhibit postfire recruitment in the short-term and shape recovery trajectories decades later. To date, the influence of climatic dipoles on large-scale, enduring patterns of forest recovery has remained largely unexplored and may improve predictions of both ecosystem transformations and species range dynamics under climate change.
Water oxidation by photosystem II is the primary source of electrons for sustained H
2
photoproduction in nutrient-replete green algae
Authors: Kosourov Sergey , Nagy Valéria , Shevela Dmitry , Jokel Martina , Messinger Johannes , Allahverdiyeva Yagut
Published: November 2020

Significance

Photosynthetic H
2
production in the green alga
Chlamydomonas reinhardtii
is catalyzed by O
2
-sensitive [FeFe]-hydrogenases, which accept electrons from photosynthetically reduced ferredoxin and reduce protons to H
2
. Since the process occurs downstream of photosystem I, the contribution of photosystem II (PSII) in H
2
photoproduction has long been a subject of debate. Indeed, water oxidation by PSII results in O
2
accumulation in chloroplasts, which inhibits H
2
evolution. Therefore, clear evidence for direct water biophotolysis resulting in simultaneous H
2
and O
2
releases in algae has never been presented. This paper demonstrates that sustained H
2
photoproduction in
C. reinhardtii
is directly linked to PSII-dependent water oxidation and brings insights into regulation of PSII activity and H
2
production by CO
2
/HCO
3
–
under microoxic conditions.
Type I interferon remodels lysosome function and modifies intestinal epithelial defense
Authors: Zhang Hailong , Zoued Abdelrahim , Liu Xu , Sit Brandon , Waldor Matthew K.
Published: November 2020

Significance

Here, a genome-scale CRISPR/Cas9 screen in epithelial cells using
Salmonella
, a prototypical intracellular pathogen, led to the discovery of a new role for IFN-I signaling. We found that this canonical antiviral signaling pathway controls the subcellular localization, protein content, pH, and protease activity of lysosomes. IFN-I signaling-dependent lysosomal acidification was associated with heightened
Salmonella
virulence gene expression and escape into the cytosol, and
in vivo
studies confirmed a role for epithelial IFN-I signaling in promoting
Salmonella
systemic infection. We propose that IFN-I signaling-mediated control of lysosome function contributes to host responses to diverse intracellular pathogens and viruses. Investigating how cytokine signaling modifies organelle function will deepen understanding of the cell biology of innate defense.
Label-free adaptive optics imaging of human retinal macrophage distribution and dynamics
Authors: Hammer Daniel X. , Agrawal Anant , Villanueva Ricardo , Saeedi Osamah , Liu Zhuolin
Published: November 2020

Significance

Microglia, a type of macrophage, were discovered a little more than a century ago by Pío del Río-Hortega. Since that time, we have gained an immense amount of knowledge on their origin and multifaceted function with the aid of labeling techniques and animal models, among other tools. Only recently have macrophage cells been imaged in living humans. Here we characterize macrophage spatial distribution and temporal dynamics in live human eyes using a label-free adaptive optics imaging approach. This investigation lays a foundation to better understand the body’s immune response not only to ocular diseases like glaucoma, but also to a vast array of neurological diseases with ocular manifestations, including Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis.
High-resolution land value maps reveal underestimation of conservation costs in the United States
Authors: Nolte Christoph
Published: November 2020

Significance

This paper presents high-resolution maps of the estimated value of private lands in the contiguous United States. The estimates permit the prediction of the cost of conservation interventions at a much higher accuracy than proxies used in previous nationwide conservation planning studies. A close look at two recent studies on US-wide floodplain protection and species conservation planning for climate change suggests that the use of previous cost proxies led to the underestimation of policy budgets necessary to achieve environmental goals by a factor of 2 and a factor of 37.5, respectively. This can undermine the validity of findings. Future analyses of conservation policies can and should use high-resolution cost estimates in their justification and spatial prioritization of interventions.
Regulating kinetics and thermodynamics of electrochemical nitrogen reduction with metal single-atom catalysts in a pressurized electrolyser
Authors: Zou Haiyuan , Rong Weifeng , Wei Shuting , Ji Yongfei , Duan Lele
Published: November 2020

Significance

The present-day industrial ammonia synthesis is overreliance on the Haber–Bosch process, yet consumes more than 1% of the global energy supply along with gigatonne greenhouse-gas emission per year. Electrochemical nitrogen reduction reaction (ENRR) offers a sustainable path to produce ammonia under mild conditions, while its efficiency achieved by far is fairly low, which requires the development of both catalysts and electrolyzers. Here, by the cooperation of densely populated metal single atoms on graphdiyne substrate with the pressurized electrocatalytic system, the kinetics and the thermodynamic driving force of ENRR are effectively regulated, leading to a record-high ammonia yield rate. This work motivates the technological and material coevolution for the ENRR toward its envisioned application.