bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionogram Echo Extraction Based on the Convolutional Neural Networks
Authors: Xue Jiawei , Zhang Chengfeng , Yin Bo , Jia Xiaoyi , Xu Jiali , Ma Mengfei
Published: June 2022

The extraction of ionospheric echo plays a key role in the research of radio wave propagation theory and is the basis of the design, application, and test of the radio engineering system. However, it is too complicated to achieve because of several negative factors, such as environmental noise, thermal noise, ionospheric time‐varying dispersion characteristics, and so on. In this paper, a novel ionospheric echoes extraction model, referred to as IECAENet, is proposed based on the convolutional neural networks. First, VGGNet is introduced as the classification module to extract echoes from different kinds of ionograms, including vertical ionograms, oblique ionograms, and backscatter ionograms. Then, the echoes extraction module is designed. It considers not only the ionogram features but also an explicit hint, named echo mask, that expresses the location of the echoes. Finally, the residual learning technology and skip connection structure are introduced to improve the performance of the module. Experimental results on a real data set indicate that IECAENet outperforms the baselines for the ionospheric echoes extraction. Using the false alarm probability that IECAENet has an optimal performance as the benchmark, the detection probabilities of the vertical ionogram, oblique ionogram, and backscatter ionogram are improved by 22.18%, 22.56%, and 6.67%, respectively, compared with the traditional methods.
Grain-size-evolution controls on lithospheric weakening during continental rifting
Authors: Ruh J. B. , Tokle L. , Behr W. M.
Published: June 2022

Variation in the effective strength of the lithosphere allows for active plate tectonics and is permitted by different deformation mechanisms operating in the crust and upper mantle. The dominant mechanisms are debated, but geodynamic models often employ grain-size-independent mechanisms or evaluate a single grain size. However, observations from nature and rock deformation experiments suggest a transition to grain-size-dependent mechanisms due to a reduction in grain size can cause lithospheric weakening. Here, we employ a two-dimensional thermo-mechanical numerical model of the upper mantle to investigate the nature of deformation and grain-size evolution in a continental rift setting, on the basis of a recent growth law for polycrystalline olivine. We find that the average olivine grain size is greater in the asthenospheric mantle (centimetre-scale grains) than at the crust–mantle boundary (millimetre-scale grains). This grain-size distribution could result in dislocation creep being the dominant deformation mechanism in the upper mantle. However, we suggest that along lithospheric-scale shear zones, a reduction in grain sizes due to localized deformation causes a transition to diffusion creep as the dominant deformation mechanism, causing weakening of the lithosphere and facilitating the initiation of continental rifting.
Rapid evaluation of COVID-19 vaccine effectiveness against symptomatic infection with SARS-CoV-2 variants by analysis of genetic distance
Authors: Cao Lirong , Lou Jingzhi , Chan See Yeung , Zheng Hong , Liu Caiqi , Zhao Shi , Li Qi , Mok Chris Ka Pun , Chan Renee Wan Yi , Chong Marc Ka Chun , Wu William Ka Kei , Chen Zigui , Wong Eliza Lai Yi , Chan Paul Kay Sheung , Zee Benny Chung Ying , Yeoh Eng Kiong , Wang Maggie Haitian
Published: June 2022

Timely evaluation of the protective effects of Coronavirus Disease 2019 (COVID-19) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern is urgently needed to inform pandemic control planning. Based on 78 vaccine efficacy or effectiveness (VE) data from 49 studies and 1,984,241 SARS-CoV-2 sequences collected from 31 regions, we analyzed the relationship between genetic distance (GD) of circulating viruses against the vaccine strain and VE against symptomatic infection. We found that the GD of the receptor-binding domain of the SARS-CoV-2 spike protein is highly predictive of vaccine protection and accounted for 86.3% (P = 0.038) of the VE change in a vaccine platform-based mixed-effects model and 87.9% (P = 0.006) in a manufacturer-based model. We applied the VE-GD model to predict protection mediated by existing vaccines against new genetic variants and validated the results by published real-world and clinical trial data, finding high concordance of predicted VE with observed VE. We estimated the VE against the Delta variant to be 82.8% (95% prediction interval: 68.7–96.0) using the mRNA vaccine platform, closely matching the reported VE of 83.0% from an observational study. Among the four sublineages of Omicron, the predicted VE varied between 11.9% and 33.3%, with the highest VE predicted against BA.1 and the lowest against BA.2, using the mRNA vaccine platform. The VE-GD framework enables predictions of vaccine protection in real time and offers a rapid evaluation method against novel variants that may inform vaccine deployment and public health responses.
500 metagenome-assembled microbial genomes from 30 subtropical estuaries in South China
Authors: Zhou Lei , Huang Shihui , Gong Jiayi , Xu Peng , Huang Xiande
Published: June 2022

As a unique geographical transition zone, the estuary is considered as a model environment to decipher the diversity, functions and ecological processes of microbial communities, which play important roles in the global biogeochemical cycle. Here we used surface water metagenomic sequencing datasets to construct metagenome-assembled genomes (MAGs) from 30 subtropical estuaries at a large scale along South China. In total, 500 dereplicated MAGs with completeness ≥ 50% and contamination ≤ 10% were obtained, among which more than one-thirds (n = 207 MAGs) have a completeness ≥ 70%. These MAGs are dominated by taxa assigned to the phylum Proteobacteria (n = 182 MAGs), Bacteroidota (n = 110) and Actinobacteriota (n = 104). These draft genomes can be used to study the diversity, phylogenetic history and metabolic potential of microbiota in the estuary, which should help improve our understanding of the structure and function of these microorganisms and how they evolved and adapted to extreme conditions in the estuarine ecosystem.
Numerical aspects of thermo migrated radiative nanofluid flow towards a moving wedge with combined magnetic force and porous medium
Authors: Haq Ehsan Ul , Khan Sami Ullah , Abbas Tasawar , Smida Kamel , Hassan Qazi Mahmood Ul , Ahmad Bilal , Khan M. Ijaz , Guedri Kamel , Kumam Poom , Galal Ahmed M.
Published: June 2022

The researchers are continuously working on nanomaterials and exploring many multidisciplinary applications in thermal engineering, biomedical and industrial systems. In current problem, the analytical simulations for performed for thermos-migration flow of nanofluid subject to the thermal radiation and porous media. The moving wedge endorsed the flow pattern. The heat source effects are also utilized to improves the heat transfer rate. The applications of thermophoresis phenomenon are addressed. The formulated set of expressions are analytically treated with implementation of variational iteration method (VIM). The simulations are verified by making the comparison the numerical date with existing literature. The VIM analytical can effectively tackle the nonlinear coupled flow system effectively. The physical impact for flow regime due to different parameters is highlighted. Moreover, the numerical outcomes are listed for Nusselt number.
Integrated bioinformatics analysis reveals marker genes and immune infiltration for pulmonary arterial hypertension
Authors: Tang Shengxin , Liu Yue , Liu Bin
Published: June 2022

Pulmonary arterial hypertension (PAH) is a chronic cardiopulmonary syndrome with high pulmonary vascular load and eventually causing RV heart failure even death. However, the mechanism of pulmonary hypertension remains unclear. The purpose of this research is to detect the underlying key genes and potential mechanism of PAH using several bioinformatic methods. The microarrays GSE22356, GSE131793 and GSE168905 were acquired from the GEO. Subsequently, a host of bioinformatics techniques such as DAVID, STRING, R language and Cytoscape were utilized to investigate DEGs between PAH and healthy controls and conduct GO annotation, KEGG enrichment analysis and PPI network construction etc. Additionally, we predicted the transcription factors regulating DEGs through iRegulon plugin of Cytoscape and CIBERSORT was used to conduct immune infiltration analysis. One thousand two hundred and seventy-seven DEGs (403 up-regulated and 874 down-regulated) were identified from peripheral blood samples of 32 PAH patients and 29 controls, among which SLC4A1, AHSP, ALAS2, CA1, HBD, SNCA, HBM, SELENBP1, SERPINE1 and ITGA2B were detected as hub genes. The functional enrichment changes of DEGs were mainly enriched in protein binding, extracellular exosome, extracellular space, extracellular region and integral component of plasma membrane. The hub genes are chiefly enriched at extracellular exosome, hemoglobin complex, blood microparticle, oxygen transporter activity. Among TF-DEGs network, 42 target DEGs and 6 TFs were predicted with an NES > 4 (TEAD4, TGIF2LY, GATA5, GATA1, GATA2, FOS). Immune infiltration analysis showed that monocytes occupied the largest proportion of immune cells. The trend analysis results of infiltration immune cells illustrated that PAH patients had higher infiltration of NK cell activation, monocyte, T cell CD4 memory activation, and mast cell than healthy controls and lower infiltration of T cell CD4 naive. We detected SLC4A1, AHSP, ALAS2, CA1, HBD, SNCA, HBM, SELENBP1, SERPINE1 and ITGA2B as the most significant markers of PAH. The PAH patients had higher infiltration of NK cell activation, monocyte, T cell CD4 memory activation, and mast cell than healthy controls and lower infiltration of T cell CD4 naive. These identified genes and these immune cells probably have precise regulatory relationships in the development of PAH.
Determination of very long-chain polyunsaturated fatty acids from 24 to 44 carbons in eye, brain and gonads of wild and cultured gilthead sea bream (Sparus aurata)
Authors: Serrano Roque , Navarro Juan C. , Sales Carlos , Portolés Tania , Monroig Óscar , Beltran Joaquin , Hernández Félix
Published: June 2022

Very long-chain (> C24) polyunsaturated fatty acids (VLC-PUFA) play an important role in the development of nervous system, retinal function and reproductive processes in vertebrates. Their presence in very small amounts in specific lipid classes, the lack of reference standards and their late elution in chromatographic analyses render their identification and, most important, their quantification, still a challenge. Consequently, a sensitive and feasible analytical methodology is needed. In this work, we have studied the effect of chain length, as well as the number and position of unsaturations (or double bonds) on the response of GC-APCI-(Q)TOF MS, to establish an analytical method for VLC-PUFA quantification. The developed methodology allows the quantification of these compounds down to 2.5 × 10–3 pmol/mg lipid. The reduction of VLC-PUFA levels in lipid fractions of the organs from the herein sampled farmed fish suggesting a yet undetected effect on these compounds of high vegetable oil aquafeed formulations, that currently dominate the market.
Photochemistry of transition metal carbonyls
Authors: Turner James J. , George Michael W. , Poliakoff Martyn , Perutz Robin N.
Published: June 2022

Ultrafast photodissociation of metal carbonyls leads to wavelength-selective photochemistry with applications in photo-induced polymerisation, catalysis, CO-release, synthesis and surface modification.
Scar prevention through topical delivery of gelatin-tyramine-siSPARC nanoplex loaded in dissolvable hyaluronic acid microneedle patch across skin barrier
Authors: Chun Yong Yao , Tan William Wei Ren , Vos Marcus Ivan Gerard , Chan Wen Kiat , Tey Hong Liang , Tan Nguan Soon , Tan Timothy Thatt Yang
Published: June 2022

Dissolvable microneedle patch made of HA designed for delivery of siSPARC across skin barrier to prevent scar formation.
A simple and versatile synthesis strategy of hollow MOFs for CO2 separation and catalysis
Authors: Shao Yanhua , Xu Jie , Low Ze-Xian , Chen Chunhong , Jiang Hong , Chen Rizhi
Published: June 2022

Hollow MOFs are fabricated using a single-solvent-interfacial strategy, and their hierarchically porous structures exhibit significant enhancement in CO2 separation and catalysis.
Photodegradation of carbonic anhydrase IXviaa binding-enhanced ruthenium-based photosensitizer
Authors: Hao Liang , Wang Jie , Pan Zheng-Yin , Mao Zong-Wan , Tan Cai-Ping
Published: June 2022

A binding-enhanced ruthenium-based photosensitizer is reported for photodegradation of carbonic anhydrase IX.
Low-crystalline nickel hydroxide nanosheets embedded with NiMoO4 nanoparticles on nickel foam for high-performance supercapacitor applications
Authors: Chen Y. B. , You J. J. , Chen Y. H. , Ma L. A. , Chen H. X. , Wei Z. H. , Ye X. Y. , Zhang L.
Published: June 2022

Nickel hydroxide nanosheets embedded with NiMoO4 nanoparticles with controllable composition were prepared. The optimized hybrid electrode exhibits high energy density.
Structural and electronic properties of pristine and hydrogen-terminated c-BN(100) surfaces
Authors: Gong Mengmeng , Liu Yaning , Gao Lilin , Gao Nan , Li Hongdong
Published: June 2022

Theoretically, the pristine and H-terminated c-BN(100) surfaces show dimer structures, determining to the corresponding band structures and electron affinity values.
Ab initio trajectory surface-hopping dynamics studies of excited-state proton-coupled electron transfer reactions in trianisoleheptazine–phenol complexes
Authors: Huang Xiang , Domcke Wolfgang
Published: June 2022

Ab initio surface-hopping dynamics simulations provide temporally and structurally resolved insight into the photoinduced proton-coupled electron transfer reaction in hydrogen-bonded complexes of trianisoleheptazine with phenol and methoxyphenol.
Donors, acceptors, and a bit of aromatics: electronic interactions of molecular adsorbates on hBN and MoS2 monolayers
Authors: Melani Giacomo , Guerrero-Felipe Juan Pablo , Valencia Ana M. , Krumland Jannis , Cocchi Caterina , Iannuzzi Marcella
Published: June 2022

The design of low-dimensional organic–inorganic interfaces for the next generation of opto-electronic applications requires in-depth understanding of the microscopic mechanisms ruling electronic interactions in these systems.
Small-angle neutron scattering from mixtures of long- and short-chain 3-alkyl-1-methyl imidazolium bistriflimides
Authors: Cabry Christopher P. , D’Andrea Lucía , Elstone Naomi S. , Kirchhecker Sarah , Riccobono Alessio , Khazal Iman , Li Peixun , Rogers Sarah E. , Bruce Duncan W. , Slattery John M.
Published: June 2022

The preparation of mixtures of ionic liquids (ILs) represents an attractive strategy to tune their properties, an important aspect of which is to understand how the structure of the bulk varies with composition.
Surface diffusion within the Caldeira–Leggett formalism
Authors: Torres-Miyares E. E. , Rojas-Lorenzo G. , Rubayo-Soneira J. , Miret-Artés S.
Published: June 2022

Intermediate scattering function for a light adsorbate considered to be distinguishable (black solid curve), boson (blue dashed curve) and fermion (red dotted curve).
An accurate many-body expansion potential energy surface for AlH2 (22A′) and quantum dynamics in Al(3P) + H2 (v0 = 0–3, j0 = 0, 2, 4, 6) collisions
Authors: Lü Yanling , Zhang ChengYuan , Wang Hainan , Guo Qiang , Li Yongqing
Published: June 2022

A new PES is constructed for the present work in hyperspherical coordinates, which depicts all stable structures for the Al(3P) + H2(X1Σg+) → AlH(a3Π) + H(2S) reaction.
Local excitation and valley polarization in graphene with multi-harmonic pulses
Authors: Saalmann Ulf , Rost Jan Michael
Published: June 2022

Excitation in the valley domains of graphene, around K (warm colors) and K′ (cold colors) are induced by vertically-polarized multi-harmonic pulses (here containing ω and 2ω) with a maximum vector potential matching the distance K–K′.
Carbon neutral methanol from pulp mills towards full energy decarbonization: an inside perspective and critical review
Authors: Pio D. T. , Vilas-Boas A. C. M. , Rodrigues N. F. C. , Mendes A.
Published: June 2022

A neutral and potentially negative carbon cycle for methanol production and use.
Biomimetic reconstruction of butterfly wing scale nanostructures for radiative cooling and structural coloration
Authors: Lee Jinwoo , Jung Yeongju , Lee MinJae , Hwang June Sik , Guo Jiang , Shin Wooseop , Min JinKi , Pyun Kyung Rok , Lee Huseung , Lee Yaerim , Shiomi Junichiro , Kim Young-Jin , Kim Byung-Wook , Ko Seung Hwan
Published: June 2022

The butterfly wing scales of several species exhibit dual functionalities of radiative cooling and structural coloring. Here, we artificially reconstruct a butterfly wing scale of periodically grating nanostructures with extremely high porosity.
A visible-light-gated donor–acceptor Stenhouse adduct chemosensor: synthesis, photochromism and naked-eye colorimetric/fluorometric sensing of Al3+ and Zn2+
Authors: Fu Peng , Yan Qing , Wang Sheng , Wu Hanlun , Cao Derong
Published: June 2022

A visible-light-gated donor–acceptor Stenhouse adduct chemosensor is designed for the colorimetric/fluorometric sensing of Al3+ and Zn2+.
Self-assembly driven chiral transfer from a dipeptide to the twist and stacking handedness of cyanobiphenylyl groups
Authors: Wu Lijia , Liu Wei , Li Yi , Yang Yonggang
Published: June 2022

The chiral transfer phenomenon was studied on four Ala–Ala lipodipeptides with a cyanobiphenylyl group at the terminal alkyl chain.
Copper(i)-catalyzed synthesis of natural alkaloid tryptanthrin and its derivatives
Authors: Hong Jiankai , Zhang Min , Shi Liang , Liu Peng , Guo Yuchao , Zhao Ting , Li Qing X. , Yang Liuqing
Published: June 2022

A facile one-pot synthesis of natural alkaloid tryptanthrin and its derivatives from isatins catalyzed by CuI in the presence of KHCO3 has been developed.
Fabrication of Fe3O4@poly(methyl methacrylate-co-glycidyl methacrylate) microspheres via miniemulsion polymerization using porous microspheres as templates for removal of cationic dyes
Authors: Man Hong , Nie Yingrui , Shao Shimin , Wang Yang , Wang Zhifei , Jiang Yong
Published: June 2022

A novel and simple method was proposed to prepare monodisperse magnetic microspheres with controllable particle sizes and different functionalities.
Synthesis and performance of PdMulti@HCS catalysts with Pd nanoparticles partially embedded in the inner wall of hollow carbon spheres for the direct synthesis of hydrogen peroxide from hydrogen and oxygen
Authors: Shi Yongyong , Jiang Donghai , Zhao Jingyun , Wu Lang , Zhao Chenchen , Ma Jun , Pan Hongyan , Lin Qian
Published: June 2022

PdMulti@HCS catalysts ensure the maximum exposure of Pd active sites and optimal transfer and diffusion ability for H2O2 synthesis.
Novel carbazole- and dioxino[2,3-b]pyrazine-based bipolar hosts for red PhOLEDs with a high brightness
Authors: Wu Haifa , Wang Guoliang , Zhang Daqing , Jin Xin , Luo Xin , Guo Shiyan , Zhou Haitao , Miao Yanqin , Huang Jinhai , Su Jianhua
Published: June 2022

The target compounds offer new synthetic ideas for red bipolar host materials.
FeIII/TBHP mediated remote C–O bond construction of 8-aminoquinolines: access to methoxylation and cyanomethoxylation
Authors: Zhao Mengfei , Zhang Kaixin , Xu Jianxiong , Li Jizhen
Published: June 2022

The C5 regioselective methoxylation and cyanomethoxylation of 8-aminoquinolines were achieved under FeIII/TBHP system by tuning the temperature and solvent. TBHP was investigated as an “oxygen” source in the ether bond formation for the first time.
Data mining for predicting gas diffusivity in zeolitic-imidazolate frameworks (ZIFs)
Authors: Krokidas Panagiotis , Karozis Stelios , Moncho Salvador , Giannakopoulos George , Brothers Edward N. , Kainourgiakis Michael E. , Economou Ioannis G. , Steriotis Theodore A.
Published: June 2022

Molecular sieving is based on mobility differences of species under extreme confinement, i.e. within pores of molecular dimensions.
On-chip high-energy interdigital micro-supercapacitors with 3D nanotubular array electrodes
Authors: Li Fei , Hu Anjun , Zhao Xiaoli , Wu Tongwei , Chen Wei , Lei Tianyu , Hu Yin , Huang Ming , Wang Xianfu
Published: June 2022

3D MnO2nanotube arrays assembled with intersecting nanoflakes are fabricatedviaa novel membrane transfer process for on-chip interdigital micro-supercapacitor, exhibiting high energy density, excellent cycling stability and desirable flexibility.
Oxygen vacancies in a catalyst for VOCs oxidation: synthesis, characterization, and catalytic effects
Authors: Zheng Yanfei , Fu Kaixuan , Yu Zhihao , Su Yun , Han Rui , Liu Qingling
Published: June 2022

This review about the recent advances in oxygen vacancies for catalytic oxidation of volatile organic compounds considers the construction strategies, characterization methods and catalytic effects of oxygen vacancies in catalysts.
A temperature-responsive selenium nanohydrogel for strawberry grey mould management
Authors: Liu Yanan , Huang Yuqin , Liu Jiawei , Liu Jie
Published: June 2022

The synthesis of an Ipr@MSe@LA nanoplatform was illustrated and its antifungal activity with temperature-responsive release in vitro and in potted strawberries was studied.
Design and analysis of double 6/3 transverse flux bearingless switched reluctance motor
Authors: Xie Kai , Huang Yonghong , Sun Yukun , Yuan Ye , Xia Dawei , Geng Jinfeng
Published: June 2022

A novel dual 6/3 Transverse Flux Bearingless Switched Reluctance Motor is proposed to solve the coupling problem between torque and suspension of conventional Switched Reluctance Motor. The working principle is introduced in detail, the motor is modelled by ANSYS, and the accurate mathematical model of the suspension force is deduced and verified. The electromagnetic characteristics of the motor are simulated, and the torque characteristics, suspension characteristics and the coupling characteristics between them are verified. The simulation results show that the torque and suspension force can be stabilised by using the zoning control of torque and suspension force, and the decoupling between torque and suspension force is excellent.
Research on current‐type high frequency resonant power converter based on magnetic energy recovery switch
Authors: Cheng Miaomiao , Jiang Keyao , Chen Kai
Published: June 2022

LCL resonant converters have been widely used to get a constant current output. This paper proposes an LCL resonant converter based on the magnetic energy recovery switch (MERS), which adjusts the output current of the converter by controlling the paralleled equivalent capacitance, as responding to the parameter errors or input voltage disturbance. Firstly, based on the equivalent model of the LCL resonant converter, the effect of variable capacitive impedance on the output current characteristics of the converter is analysed. Then the topological structure of MERS is introduced and its working principle as a controllable capacitive impedance controller is further explained. On this basis, the operating characteristics and soft switching characteristics of the proposed topology in each complete working cycle are analysed in detail. By controlling the phase shift angle between the output voltage of bridge and the fundamental component of MERS voltage, the equivalent capacitance of the MERS is changed, and the resonant frequency of the converter is accordingly adjusted to accurately compensate the output current against the input voltage disturbance. Finally, the effectiveness and feasibility of the MERS applied to the LCL resonant converter are verified by simulation and experiments. Besides, its operating characteristics are analysed and evaluated.
Simulation of a non‐linear, time‐variant circuit using the Haar wavelet transform
Authors: Roumeliotis Georgios G. , Desmet Jan , Knockaert Jos
Published: June 2022

Wavelet theory has disentangled numerous complexities, including those pertinent to transient and steady‐state responses of systems, when Laplace and Fourier transforms face insoluble obstacles. Reactive linear components (e.g. inductors and capacitors) are typically handled in the frequency plane. Non‐linear (e.g. diodes) or time‐variant components (e.g. switches) are conventionally simulated in the time plane (e.g. a diode via its I–V characteristic) and are considered open or short circuits in AC analyses (e.g. in circuit simulation software). Although translating circuits in an alternative plane, such as the Haar wavelet plane, significantly simplifies the process, a wide integration of wavelets into instruments and education is not yet realised; an underlying reason is the considerate complexity of applying wavelet theory to circuits and signals. The aim of this paper is to bridge this gap, providing a new user‐friendly, Laplace‐alike approach, utilising measurement‐based models and the Haar wavelet. The Haar wavelet transform and a numerical method for the inverse Laplace transform which uses the Haar operational matrix are applied, to calculate the total current of a non‐linear, time‐variant system, that is the total current of a voltage source which powers a non‐linear, time‐variant load.
Dynamic air ticket pricing using reinforcement learning method
Authors: Gao Jinmin , Le Meilong , Fang Yuan
Published: June 2022

This paper studies a dynamic air ticket pricing problem in a strategic and myopic passengers co-existence market. The strategic or myopic passengers can be further divided into high-valuation and low-valuation groups according to how they evaluate their purchases. The strategic passengers have different strategic levels. When the airline sets a ticket price, every passenger makes his or her purchase decision according to his or her type and the strategic level, or might select “wait” or “leave (the market)”. The paper firstly proposes a dynamic pricing algorithm in which the utilities of both the airline and passengers are considered. The reinforcement learning (RL) is employed to deal with the progressive or dynamic decision-making framework, in which the dynamic pricing problem is formulated as a discrete finite Markov decision process (MDP) and the Q-learning is adopted to solve the problem. By using this method, the airline can adaptively decide the ticket price based on passengers strategic behaviors and the time-varying demand. The effects of the passenger type proportion and strategic level are analyzed. The computational results show the higher proportion of strategic passengers is, the smaller price increase the airline can adopt, and the higher proportion of high-valuation strategic passengers is, the larger price increase the airline can put to use under the same strategic level. If the proportion of low-valuation strategic passengers is higher, the price increase should be gentle and step by step when the price increase strategy is adopted. If the airline uses price-cut policy, the adjustment should be small. In addition, the high-valuation passenger mainly affects high-price periods and the low-valuation passenger mainly affects low-price periods. When the proportion of strategic passengers is fixed, the lower the passenger strategic level is, the larger the price slope is. These findings can provide some references for the airline to make more precise and flexible pricing decisions.
Photochemical Activation of Sulfur Hexafluoride: A Tool for Fluorination and Pentafluorosulfanylation Reactions
Authors: Rombach David , Wagenknecht Hans-Achim
Published: June 2022

The photoactivation of notoriously inert sulfur hexafluoride represents a challenge for photochemistry. This short review summarizes recently published efforts and the corresponding photochemical mechanisms for switching between the fluorination and pentafluorosulfanylation reactivity of organic substrates.

1 Introduction

2 Sulfur Hexafluoride (SF6)

3 The Pentafluorosulfanyl (SF5) Group

4 Photoredox Catalytic Activation of SF6

5 Conclusions
Infective Endocarditis in Pregnancy: A Contemporary Cohort
Authors: Countouris Malamo E. , Marino Amy L. , Raymond Megan , Hauspurg Alisse , Berlacher Kathryn L.
Published: June 2022

Objective Pregnancy-related infective endocarditis (IE) caries a high risk of morbidity and mortality. With increasing intravenous drug abuse (IVDA) amid the opioid epidemic, the risk factor profile may be shifting. In this case series, we aimed to describe risk factors and outcomes for peripartum IE in a contemporary cohort.

Study Design We identified patients with IE diagnosed during pregnancy or up to 6 weeks' postpartum from 2015 through 2018 at a single tertiary care center. We abstracted detailed medical history and clinical outcome measures from the electronic medical record. The diagnosis of IE was supported by the modified Duke Criteria.

Results Nine patients had peripartum IE: eight (89%) with a history of IVDA, one with an indwelling central venous catheter (11%), and one with prior IE (11%). None had preexisting congenital or valvular heart disease. Six (67%) had comorbid hepatitis C. Eight cases (89%) had gram-positive cocci with vegetations involving the tricuspid valve (56%) and both mitral and tricuspid valves (22%). Major complications included shock (33%), mechanical ventilation (44%), septic emboli (67%), and noncardiac abscesses (33%). Two patients underwent valve surgery, and there were two cases of postpartum maternal mortality (22%), one from septic shock and one from intracerebral hemorrhage. While four patients (44%) delivered preterm (average gestational age 35 weeks), most delivered vaginally (89%) with only one requiring an emergent caesarean section. There was no fetal mortality, although three newborns (43%) required admission to the neonatal intensive care unit. Two patients were initiated on medication-assisted treatment for opioid use disorder. Consultants included infectious disease, cardiology, cardiac surgery, maternal-fetal medicine, and psychiatry.

Conclusion These findings confirm that IVDA is a growing risk factor for pregnancy-related IE. Peripartum IE carries a high risk of complications, including maternal mortality, and warrants management with a multidisciplinary care team at a tertiary center.

Key Points
Pregnant Populations which Benefit from Vaginal Progesterone for Preventing Preterm Birth at <34 Weeks and Neonatal Morbidities: A Systematic Review and Meta-analysis
Authors: Lin Xiaobin , Nie Yu
Published: June 2022

This study aimed to assess vaginal progesterone's effect on different populations and performed comparation between women with varied risk factors. Embase, PubMed, Cochrane library (CENTRAL) were searched without restriction to language up to February 25, 2021. Randomized controlled trials (RCTs) assessing vaginal progesterone administered to women at risk of preterm birth at <37 weeks. Two reviewers independently extracted data, and pooled relative risk (RR) with 95% confidence intervals (CIs) was calculated as well. Women with short cervix have a significantly lower risk of preterm birth at <34 weeks (pooled RR = 0.65; 95% CI: 0.55–0.77; I
2 = 0; p < 0.001; nine studies) and some neonatal morbidities; interaction tests showed that effect of vaginal progesterone differs significantly between women with short cervix and those with other risk factors (history of preterm birth, exclusive twin gestation, and vaginal bleeding). Evidences of this study showed that singleton gestations, as well as women with short cervix, benefit from vaginal progesterone in preventing preterm birth at <34 weeks and some neonatal morbidities. Women with short cervix are populations who benefit the most among other risk populations.

Key Points
DLK1: A Novel Biomarker of Placental Insufficiency in Stillbirth and Live Birth
Authors: Page Jessica M. , Allshouse Amanda A. , Gaffney Jessica E. , Roberts Victoria H. J. , Thorsten Vanessa , Gibbins Karen J. , Dudley Donald J. , Saade George , Goldenberg Robert L. , Stoll Barbara J. , Hogue Carol J. , Bukowski Radek , Parker Corette , Conway Deborah , Reddy Uma M. , Varner Michael W. , Frias Antonio E. , Silver Robert M.
Published: June 2022

Objective Delta-like homolog 1 (DLK1) is a growth factor that is reduced in maternal sera in pregnancies with small for gestational age neonates. We sought to determine if DLK1 is associated with stillbirth (SB), with and without placental insufficiency.

Study Design A nested case-control study was performed using maternal sera from a multicenter case-control study of SB and live birth (LB). SB and LB were stratified as placental insufficiency cases (small for gestational age <5% or circulatory lesions on placental histopathology) or normal placenta controls (appropriate for gestational age and no circulatory lesions). Enzyme-linked immunosorbent assay (ELISA) was used to measure DLK1. The mean difference in DLK1 was compared on the log scale in an adjusted linear regression model with pairwise differences, stratified by term/preterm deliveries among DLK1 results in the quantifiable range. In exploratory analysis, geometric means were compared among all data and the proportion of “low DLK1” (less than the median value for gestational age) was compared between groups and modeled using linear and logistic regression, respectively.

Results Overall, 234 SB and 234 LB were analyzed; 246 DLK1 values were quantifiable within the standard curve. Pairwise comparisons of case and control DLK1 geometric means showed no significant differences between groups. In exploratory analysis of all data, adjusted analysis revealed a significant difference for the LB comparison only (SB: 71.9 vs. 99.1 pg/mL, p = 0.097; LB: 37.6 vs. 98.1 pg/mL, p = 0.005). In exploratory analysis of “low DLK1,” there was a significant difference between the odds ratio of having “low DLK1” between preterm cases and controls for both SB and LB. There were no significant differences in geometric means nor “low DLK1” between SB and LB.

Conclusion In exploratory analysis, more placental insufficiency cases in preterm SB and LB had “low DLK1.” However, low DLK1 levels were not associated with SB.

Key Points
Adverse Pregnancy Outcomes in Nondiabetic Patients with an Elevated Early Pregnancy HbA1c
Authors: Bender Whitney R. , McCarthy Clare , Elovitz Michal , Parry Samuel , Durnwald Celeste
Published: June 2022

Objective This study aimed to evaluate the impact of elevated early hemoglobin A1c (HbA1c) values on perinatal outcomes in patients without a diagnosis of diabetes or gestational diabetes.

Study Design This is a retrospective study of patients with a singleton pregnancy who underwent universal HbA1c screening in early pregnancy at an urban tertiary care center between December 1, 2016, and December 31, 2018. Patients with pregestational diabetes mellitus (DM) and gestational DM (GDM) were excluded from analysis. The exposure of interest was HbA1c of 5.7 to 6.4% as measured on routine prenatal bloodwork at or during 16 weeks' gestation. The following pregnancy outcomes were assessed: preterm delivery <37 weeks, hypertensive disorders of pregnancy, shoulder dystocia, macrosomia (birth weight >4,000 g), small or large for gestational age neonate, operative vaginal delivery, third- or fourth-degree lacerations, cesarean delivery, neonatal intensive care unit (NICU) admission, neonatal hypoglycemia, and neonatal hyperbilirubinemia. Multivariable regression was performed to assess the relationship between HbA1c and selected adverse outcomes while controlling for potential confounders

Results Of the 2,621 patients who met inclusion criteria, 334 (12.7%) had an elevated HbA1c of 5.7 to 6.4%. Patients with an elevated HbA1c were more likely to be older, Black, multiparous, publically insured, obese, or have chronic hypertension than patients with normal HbA1c values. In the unadjusted analysis, patients with an elevated HbA1c were less likely to deliver at term (84.7 vs. 92.4%, p = 0.006), but more likely to undergo cesarean section (32.8 vs. 27.6%, p = 0.038), develop hypertensive disorders of pregnancy (31.9 vs. 23.2%, p = 0.001), or deliver a macrosomic infant (10.5 vs. 6.8%, p = 0.016) than those with a normal A1c. After adjusting for race, body mass index, insurance status, nulliparity, and age, however, only the relationship between HbA1c and spontaneous preterm birth remained significant (adjusted odds ratio [aOR] = 1.76, 95% confidence interval [CI]: 1.01–3.07).

Conclusion In our urban population, an elevated early HbA1c was associated with spontaneous preterm birth in nondiabetic patients

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Facelift Techniques: An Overview
Authors: Kaya Kerem Sami , Cakmak Ozcan
Published: June 2022

Facelift techniques can be classified according to the depth and extent of the dissection applied. Imbrication and plication of the superficial musculoaponeurotic system (SMAS) referred to as “SMAS lifts” or “classical facelifts” are the most commonly used techniques. Plication techniques involve in-folding of the SMAS and suture suspension without any SMAS incision whereas imbrication techniques involve a SMAS incision with a portion of the SMAS either removed or transposed with or without limited sub-SMAS dissection. Aging changes in the lower face and neck can be successfully treated with SMAS lift techniques. However, there is no lifting effect at midface level or improvement in the nasolabial folds since the retaining (zygomatic cutaneous and masseteric cutaneous) ligaments that prevent the transmission of traction to the malar portion of the facelift dissection are not released. Extended facelift techniques involve surgical release of these ligaments, and produce combined, balanced, and harmonious rejuvenation of the midface, cheek, and lower face without requiring a separate midface lift procedure. There are different techniques having similar extended midface dissections with some variations: The extended SMAS technique involves a long skin flap and a distinct SMAS flap dissected and pulled separately. The high SMAS technique has a similar dissection but involves a higher SMAS flap along the superior border of the zygomatic arch. The deep plane facelift involves undermining of skin-SMAS flap as a single unit following a more limited subcutaneous dissection. In the composite plane facelift, in addition to deep plane facelift dissection, the lower part of the orbicularis oculi muscle is also dissected and included in the flap. As they have a single unit, deep and composite flap facelifts allow excellent blood supply to the overlying skin. In this article, various facelift techniques are discussed in detail in line with the relevant surgical anatomy.
Predicting Progression from Gestational Diabetes to Impaired Glucose Tolerance Using Peridelivery Data: An Observational Study
Authors: Bengtson Angela M. , Dice Ana Lucia Espinosa , Clark Melissa A. , Gutman Roee , Rouse Dwight , Werner Erika
Published: June 2022

Objective This article aimed to develop a predictive model to identify persons with recent gestational diabetes mellitus (GDM) most likely to progress to impaired glucose tolerance postpartum.

Study Design We conducted an observational study among persons with GDM in their most recent pregnancy, defined by Carpenter-Coustan criteria. Participants were followed up from delivery through 1-year postpartum. We used lasso regression with k-fold cross validation to develop a multivariable model to predict progression to impaired glucose tolerance, defined as HbA1c≥5.7%, at 1-year postpartum. Predictive ability was assessed by the area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values (PPV and NPV).

Results Of 203 participants, 71 (35%) had impaired glucose tolerance at 1-year postpartum. The final model had an AUC of 0.79 (95% confidence interval [CI]: 0.72, 0.85) and included eight indicators of weight, body mass index, family history of type 2 diabetes, GDM in a prior pregnancy, GDM diagnosis<24 weeks' gestation, and fasting and 2-hour plasma glucose at 2 days postpartum. A cutoff point of ≥ 0.25 predicted probability had sensitivity of 80% (95% CI: 69, 89), specificity of 58% (95% CI: 49, 67), PPV of 51% (95% CI: 41, 61), and NPV of 85% (95% CI: 76, 91) to identify women with impaired glucose tolerance at 1-year postpartum.

Conclusion Our predictive model had reasonable ability to predict impaired glucose tolerance around delivery for persons with recent GDM.

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Identification of Distinct Risk Factors for Antepartum and Postpartum Preeclampsia in a High-Risk Safety-Net Hospital
Authors: Picon Michelle , Stanhope Kaitlyn K. , Jamieson Denise J. , Boulet Sheree L.
Published: June 2022

Objective Postpartum preeclampsia (PE), defined as de novo PE that develops at least 48 hours following delivery, can be particularly dangerous as many patients are already discharged at that point. The goal of our study was to identify risk factors uniquely associated with the development of late postpartum preeclampsia (PPPE).

Study Design In a retrospective cohort study of deliveries between July 1, 2016 and June 30, 2018 at a safety-net hospital in Atlanta, Georgia, we used multinomial logistic regression models to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for associations between demographic, medical, and obstetric factors and development of PE, categorized as a three-level outcome: no PE, antepartum/intrapartum preeclampsia (APE) (diagnosed prior to or < 48 hours of delivery), and late PPPE (diagnosed ≥ 48-hour postpartum).

Results Among 3,681 deliveries, women were primarily of ages 20 to 35 years (76.4%), identified as non-Hispanic Black (68.5%), and covered by public health insurance (88.6%). PE was diagnosed prior to delivery or within 48-hour postpartum in 12% (n = 477) of the study population, and 1.5% (57) developed PE greater than 48-hour postpartum. In the adjusted models, maternal age ≥ 35, race/ethnicity, nulliparity, a diagnosis of pregestational or gestational diabetes, and chronic hypertension were associated with increased odds of APE only, while maternal obesity (OR: 1.9; 95% CI: 1.0–3.5) and gestational hypertension (OR: 2.7; 95% CI: 1.5–4.8) were uniquely associated with PPPE. Multifetal gestations and cesarean delivery predicted both PPPE and APE; however, the association was stronger for PPPE.

Conclusion Patients with obesity, gestational hypertension, multifetal gestations, or cesarean delivery may benefit from additional follow-up in the early postpartum period to detect PPPE.

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Incidence of Gestational Diabetes Diagnosed on the 100-G Glucose Tolerance Test in Pregnancies with a 50-G Glucose Challenge Test Result of 200 mg/dL or Greater
Authors: Lord Megan G. , Agee Robert L. , Sood Nikki , Clark Melissa , Johnson Isaiah M.
Published: June 2022

Objective This study aimed to assess the positive predictive value (PPV) of a 1-hour, 50-g glucose challenge test (GCT) result ≥200 mg/dL for the diagnosis of gestational diabetes mellitus (GDM) on a 3-hour, 100-g glucose tolerance test (GTT).

Study Design Pregnancies between 2008 and 2016 with a GCT result ≥200 mg/dL were identified retrospectively. GCT and GTT dates and results, demographics, and working due date (EDD) were extracted. Gestational age at testing was calculated from test date and EDD. As some clinicians presumptively diagnose GDM in such cases, if a GTT result was not available, clinic notes were reviewed to determine whether a GTT was ordered. Positive predictive values (PPV) were calculated at GCT cut-offs at and beyond 200 mg/dL. Subgroups were compared including early GCT (<16 weeks) versus routine GCT (24–28 weeks), GTT result normal versus GTT diagnostic of GDM, and GTT ordered versus GTT not ordered. Rates of use of medication for glycemic control were assessed among these groups.

Results Of 236 pregnant women with a GCT result ≥200 mg/dL, 115 (48%) GTT was ordered for 115 (49%), whereas 123 (52%) were managed as presumed GDM. Of 100 (87%) who completed the test, 81 (81%) were diagnosed with GDM with a median intertest interval of 14 days. No statistically significant differences were found between groups stratified by GTT result. Use of rates of metformin, glyburide, and insulin were similar between those diagnosed with GDM by GTT and those diagnosed with GDM by GCT alone.

Conclusion A GCT result of ≥200 mg/dL has a PPV of 81% for diagnosis of GDM by GTT in a contemporary U.S. population, with a median intertest interval of 14 days between GCT and GTT. However, those diagnosed by GCT alone were as likely as those diagnosed by GTT to require medication for glycemic control, including insulin, suggesting that requiring a GTT may result in underdiagnosis and delayed treatment of GDM.

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Population-Level Study on Fetal Deaths and Preterm Births during SARS-CoV-2 Pandemic in the State of Michigan
Authors: Bajaj Monika , Romero Roberto , Myers Lindsey , Duncan Jeffrey , Yeo Lami , Jani Sanket , Natarajan Girija
Published: June 2022

Objective The aim of the study is to explore the effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic on preterm birth at different gestational ages and fetal death in the state of Michigan.

Study Design Data on live births and fetal deaths in the state of Michigan from March to November in the years 2017 through 2020 were obtained from Michigan Department of Health and Human Services (MDHHS). Preterm birth rate, fetal death rate (per 1,000 live births) overall and stratified by race and maternal comorbidities during the period of pandemic (March–November 2020) were compared with the same period (March–November) in the prepandemic years (2017–2019).

Results Of 328,879 live births and 1,470 fetal deaths during the study period, 77,983 live births and 242 fetal deaths were reported in 2020. Compared with prepandemic years, fetal death rate per 1,000 live births was significantly lower in 2020 (3.1 vs. 4.7 [2017], 5.2 [2018], 4.4 [2019], p-value <0.001). The adjusted risk for fetal death in 2020 was decreased (odds ratio [OR] = 0.64 [95% confidence interval (CI): 0.56–0.74], p <0.0001), compared with prepandemic years. Fetal death was significantly associated with African-American race, pregnancy hypertension and prepregnancy diabetes. No significant difference in the proportion of preterm births (<37 weeks' gestation) was noted between pandemic and prepandemic years (9.9 vs. 10.0%, p = 0.50). There was no significant difference in the risk of preterm birth across gestational age strata (<28, 28–316/7, 32–366/7, 37–416/7, and >42 weeks) between pandemic and prepandemic years on multinomial analysis. Significant associations with preterm birth across all years included African American race, lower level of maternal education, pregnancy-induced hypertension, chronic hypertension, prepregnancy diabetes, congenital anomalies, previous preterm birth, and prolonged rupture of membranes >12 hours.

Conclusion Fetal death rate was significantly lower whereas preterm births remained unchanged during pandemic in comparison with prepandemic years in the state of Michigan.

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Vortex patch problem for steady lake equation
Authors: Cao Daomin , Qin Guolin , Zou Changjun
Published: June 2022

We study the vortex patch problem for the steady lake equation in a bounded domain and construct three different kinds of solutions where the vorticity concentrates in the domain or near the boundary. Our approach is based on the Lyapunov–Schmidt reduction, which transforms the construction into a problem of seeking critical points for a function related to the kinetic energy. The method in this paper has a wide applicability and can be used to deal with general elliptic equations in divergence form with Heaviside nonlinearity.