bluuebunny/crossref_metadata_2025 huggingface dataset:
Hsa_circ_0001649 restrains gastric carcinoma growth and metastasis by downregulation of miR‐20a
Authors: Sun Haiyuan , Wang Qunying , Yuan Gang , Quan Jingzi , Dong Dongfang , Lun Yue , Sun Bo
Published: March 2020

Background

Gastric carcinoma (GC) is a familiar carcinoma and serious threat to human health. We investigated the efficacy and mechanism of circular RNA hsa_circ_0001649 on the growth, migration, and invasion of GC cells.

Methods

microRNA (miR)‐20a and hsa_circ_0001649 expression was investigated by RT‐qPCR and was changed by cell transfection. CCK‐8, flow cytometry, and BrdU assays were, respectively, used to investigate the efficacies of hsa_circ_0001649 and miR‐20a on cell viability, apoptosis, and proliferation. Transwell assay was used to investigate the efficacies of hsa_circ_0001649 and miR‐20a on cell migration and invasion. Moreover, the levels of cyclin D1, Bax, cleaved caspase‐3, and signal pathway‐related proteins were investigated by Western blot.

Results

Hsa_circ_0001649 was downregulated in GC cells and tissues. Upregulation of hsa_circ_0001649 restrained viability, proliferation, migration, and invasion, while promoted apoptosis. Furthermore, miR‐20a was negatively regulated by hsa_circ_0001649 and miR‐20a overexpression reversed the efficacy of hsa_circ_0001649 upregulation. Finally, upregulation of hsa_circ_0001649 restrained ERK and Wnt/β‐catenin pathways while miR‐20a overexpression reversed these progresses.

Conclusion

Upregulation of hsa_circ_0001649 restrained GC cell growth and metastasis by downregulating miR‐20a and thereby inactivated ERK and Wnt/β‐catenin pathways.
Quantifying background nitrate removal mechanisms in an agricultural watershed with contrasting subcatchment baseflow concentrations
Authors: Zell Wesley O. , Culver Teresa B. , Sanford Ward E. , Goodall Jonathan L.
Published: March 2020

Numerous studies have documented the linkages between agricultural nitrogen loads and surface water degradation. In contrast, potential water quality improvements due to agricultural best management practices are difficult to detect because of the confounding effect of background nitrate removal rates, as well as the groundwater‐driven delay between land surface action and stream response. To characterize background controls on nitrate removal in two agricultural catchments, we calibrated groundwater travel time distributions with subsurface environmental tracer data to quantify the lag time between historic agricultural inputs and measured baseflow nitrate. We then estimated spatially distributed loading to the water table from nitrate measurements at monitoring wells, using machine learning techniques to extrapolate the loading to unmonitored portions of the catchment to subsequently estimate catchment removal controls. Multiple models agree that in‐stream processes remove as much as 75% of incoming loads for one subcatchment while removing <20% of incoming loads for the other. The use of a spatially variable loading field did not result in meaningfully different optimized parameter estimates or model performance when compared with spatially constant loading derived directly from a county‐scale agricultural nitrogen budget. Although previous studies using individual well measurements have shown that subsurface denitrification due to contact with a reducing argillaceous confining unit plays an important role in nitrate removal, the catchment‐scale contribution of this process is difficult to quantify given the available data. Nonetheless, the study provides a baseline characterization of nitrate transport timescales and removal mechanisms that will support future efforts to detect water quality benefits from ongoing best management practice implementation.
Magnetic carbon nanotube as a highly stable and retrievable support for the heterogenization of sulfonic acid and its application in the synthesis of 2‐(1H‐tetrazole‐5‐yl) acrylonitrile derivatives
Authors: Akbarzadeh Parisa , Koukabi Nadiya , Hosseini Maliheh M.
Published: March 2020

In the present study, a novel magnetic carbon nanotube functionalized by chlorosulfonicacid (Fe3O4‐CNT‐SO3H) with nanotube morphology decorated by the spherical nanoparticles was prepared, characterized and introduced as a retrievable magnetic heterogeneous nanocatalyst for green synthesis a variety of 2‐(1H‐tetrazole‐5‐yl) acrylonitrile via multicomponent domino Knoevenagel condensation/ 1,3‐dipolar cycloaddition reaction between aromatic aldehydes, malononitrile, and sodium azide under solvent free conditions. The catalyst was magnetically separated from the reaction system by an outer magnetic force and recycled up to five runs without a remarkable loss in its efficiency. The as‐preparedacidic magnetic nanocomposite was characterized by different techniques inclusive Fourier transform infrared, thermogravimetric analysis, energy dispersive X‐ray, field emission scanning electron microscopy, X‐ray diffraction, vibrating sample magnetometry, CHNS elemental analysis, and acid‐base titration. Easy workup, affordability, elimination of volatile and toxic solvents, and high yield of products are some merits of this protocol.
Synthesis of some oxazolo and oxazinopyrano[3,2‐c]quinolines and their antitumor activity
Authors: Abdel‐Kader Dalia , Abass Mohamed
Published: March 2020

3‐Amino‐4‐hydroxy‐6‐phenylpyrano[3,2‐c]quinoline‐2,5(6H)‐dione was produced by a smooth reduction of its nitro precursor. Reaction of this 3‐amino‐4‐hydroxypyranoquinoline derivative with different electrophiles, leading to a variety of oxazolo and oxazinopyrano[3,2‐c]quinoline derivatives, was described. The structure of the new products was elucidated via elemental analysis, IR, 1H NMR, 13C NMR, and mass spectra. Also, screening the antitumor activity of new compounds against two human cell lines (HepG‐2 and HCT‐116) was carried out. Some new products showed significant antitumor activities.
Sjögren‐Larsson syndrome: The mild end of the phenotypic spectrum
Authors: Staps Pippa , van Gaalen Judith , van Domburg Peter. , Steijlen Peter M. , Ferdinandusse Sacha , den Heijer Tom , Seyger Marieke M. B. , Theelen Thomas , Willemsen Michèl A. A. P.
Published: March 2020

Sjögren‐Larsson syndrome (SLS) is a rare inborn error of lipid metabolism. The syndrome is caused by mutations in the ALDH3A2 gene, resulting in a deficiency of fatty aldehyde dehydrogenase. Most patients have a clearly recognizable severe phenotype, with congenital ichthyosis, intellectual disability, and spastic diplegia. In this study, we describe two patients with a remarkably mild phenotype. In both patients, males with actual ages of 45 and 61 years, the diagnosis was only established at an adult age. Their skin had been moderately affected from childhood onward, and both men remained ambulant with mild spasticity of their legs. Cognitive development, as reflected by school performance and professional career, had been unremarkable. Magnetic resonance spectroscopy of the first patient was lacking the characteristic lipid peak. We performed a literature search to identify additional SLS patients with a mild phenotype. We compared the clinical, radiologic, and molecular features of the mildly affected patients with the classical phenotype. We found 10 cases in the literature with a molecular proven diagnosis and a mild phenotype. Neither a genotype‐phenotype correlation nor an alternative explanation for the strikingly mild phenotypes was found. New biochemical techniques to study the underlying metabolic defect in SLS, like lipidomics, may in the future help to unravel the reasons for the exceptionally mild phenotypes. In the meantime, it is important to recognize these mildly affected patients to provide them with appropriate care and genetic counseling, and to increase our insights in the true disease spectrum of SLS.
Optimization of norbornyl‐based carbocyclic nucleoside analogs as cyclin‐dependent kinase 2 inhibitors
Authors: Köprülüoğlu Cemal , Dejmek Milan , Šála Michal , Ajani Haresh , Hřebabecký Hubert , Fanfrlík Jindřich , Jorda Radek , Dračínský Martin , Procházková Eliška , Šácha Pavel , Kryštof Vladimír , Hobza Pavel , Lepšík Martin , Nencka Radim
Published: March 2020

We report on the discovery of norbornyl moiety as a novel structural motif for cyclin‐dependent kinase 2 (CDK2) inhibitors which was identified by screening a carbocyclic nucleoside analogue library. Three micromolar hits were expanded by the use of medicinal chemistry methods into a series of 16 novel compounds. They had prevailingly micromolar activities against CDK2 and the best compound of the series attained IC50 of 190 nM. The binding modes were explored in molecular details by modeling and docking. Quantum mechanics‐based scoring was used to rationalize the affinities. In conclusion, the discovered 9‐hydroxymethylnorbornyl moiety was shown by joint experimental‐theoretical efforts to be able to serve as a novel substituent for CDK2 inhibitors. This finding opens door to the exploration of chemical space towards more effective derivatives targeting this important class of protein kinases.
Noninvasive Prediction of High‐Grade Prostate Cancer via Biparametric MRI Radiomics
Authors: Gong Lixin , Xu Min , Fang Mengjie , Zou Jian , Yang Shudong , Yu Xinyi , Xu Dandan , Zhou Lijuan , Li Hailin , He Bingxi , Wang Yan , Fang Xiangming , Dong Di , Tian Jie
Published: March 2020

Background

Gleason score (GS) is a histologic prognostic factor and the basis of treatment decision‐making for prostate cancer (PCa). Treatment regimens between lower‐grade (GS ≤7) and high‐grade (GS >7) PCa differ largely and have great effects on cancer progression.

Purpose

To investigate the use of different sequences in biparametric MRI (bpMRI) of the prostate gland for noninvasively distinguishing high‐grade PCa.

Study Type

Retrospective.

Population

In all, 489 patients (training cohort: N = 326; test cohort: N = 163) with PCa between June 2008 and January 2018.

Field Strength/Sequence

3.0T, pelvic phased‐array coils, bpMRI including T2‐weighted imaging (T2WI) and diffusion‐weighted imaging (DWI); apparent diffusion coefficient map extracted from DWI.

Assessment

The whole prostate gland was delineated. Radiomic features were extracted and selected using the Kruskal–Wallis test, the minimum redundancy‐maximum relevance, and the sequential backward elimination algorithm. Two single‐sequence radiomic (T2WI, DWI) and two combined (T2WI‐DWI, T2WI‐DWI‐Clinic) models were respectively constructed and validated via logistic regression.

Statistical Tests

The Kruskal–Wallis test and chi‐squared test were utilized to evaluate the differences among variable groups. P < 0.05 determined statistical significance. The area under the receiver operating characteristic curve (AUC), specificity, sensitivity, and accuracy were used to evaluate model performance. The Delong test was conducted to compare the differences between the AUCs of all models.

Result

All radiomic models showed significant (P < 0.001) predictive performances. Between the single‐sequence radiomic models, the DWI model achieved the most encouraging results, with AUCs of 0.801 and 0.787 in the training and test cohorts, respectively. For the combined models, the T2WI‐DWI models acquired an AUC of 0.788, which was almost the same with DWI in the test cohort, and no significant difference was found between them (training cohort: P = 0.199; test cohort: P = 0.924).

Data Conclusion

Radiomics based on bpMRI can noninvasively identify high‐grade PCa before the operation, which is helpful for individualized diagnosis of PCa.

Level of Evidence

4

Technical Efficacy Stage

2 J. Magn. Reson. Imaging 2020;52:1102–1109.
Prognostic Value of Tumor Staging: Predicting Nodal Metastases in Cutaneous Squamous Cell Carcinoma
Authors: Upton Montana , Kita Ashley , Scapa Jason , St. John Maie
Published: March 2020

Objectives

Determine the ability of three staging systems to stratify the risk of nodal metastases in cases of cutaneous squamous cell carcinoma (cSCC). Examine differential staging of tumors across the three systems and the resulting implications for clinical decision making.

Study Design

Retrospective chart review.

Methods

This study included 118 patients who underwent excision of primary cSCC of the head and neck as well as elective neck dissection for the same tumor between 2006 and 2017. Tumors were staged using the 2010 7th edition American Joint Committee on Cancer (AJCC 7) staging system, the 2016 8th edition AJCC staging system (AJCC 8), and the Brigham and Women's Hospital (BWH) alternative tumor staging system published in 2013.

Results

There were 28 patients (23.7%) with positive nodal metastases at the time of tumor excision. Almost all tumors staged as tumor (T)2 using AJCC 7 were upstaged to T3 or T4 using the new AJCC 8, and these two groups accounted for the majority of the nodal metastases. Similarly, the BWH‐staged T3 group contained the highest number of tumors with nodal metastases. None of the three staging systems significantly stratified tumors in a manner that predicted the presence of nodal metastases.

Conclusion

Individuals with cSCC tumors staged T3 or higher in the AJCC 8 and BWH staging systems should undergo neck dissection, whereas those with lower staging should be discussed with the patient on a case‐by‐case basis.

Level of Evidence: 4
A Prospective Observational Study of Video Laryngoscopy Use in Difficult Airway Management
Authors: Hyman Jaime B. , Apatov David , Katz Daniel , Levine Adam I. , DeMaria Samuel
Published: March 2020

Objectives/Hypothesis

Video laryngoscopy has grown tremendously in popularity over the last decade for management of the anticipated difficult airway. The use of video laryngoscopy has not been adequately studied in the head and neck pathology patient population, including those with masses, previous head and neck surgery, or radiation.

Study Design

Prospective observational study.

Methods

This study included 100 patients with head and neck pathology undergoing awake flexible bronchoscopic intubation for nonemergency surgery requiring general anesthesia. After the performance of awake flexible bronchoscopic intubation and induction of anesthesia, video laryngoscopy was performed with the CMAC D blade and Glidescope AVL. The primary outcome was the modified Cormack‐Lehane view obtained on video laryngoscopy.

Results

One hundred patients were enrolled in the study. After exclusions, 92 patients underwent video laryngoscopy with both the CMAC D blade and the Glidescope AVL. Thirty‐seven patients (40.2%) had a Cormack‐Lehane view ≥3 with the CMAC D blade, and 28 patients (30.4%) had a Cormack‐Lehane view ≥3 with the Glidescope AVL. There were no complications from awake flexible bronchoscopic intubation or video laryngoscopy.

Conclusions

There is a high incidence of inability to obtain a view of the glottis with video laryngoscopy in patients with head and neck pathology, particularly airway masses.

Level of Evidence

3 Laryngoscope, 131:82–86, 2021
Land management to reconcile ecosystem services supply and demand mismatches—A case study in Shanghai municipality, China
Authors: Jiang Bo , Bai Yang , Chen Junyu , Alatalo Juha M. , Xu Xibao , Liu Gang , Wang Qing
Published: March 2020

City managers need to understand how land use and land cover (LULC) change in an urban landscape can affect future land degradation and conditions for ecosystem services (ESs) supply and demand. Optimal land use and land management requires explicit spatial mapping of ESs supply and demand under alternative land use scenarios. In this study, we applied spatially explicit models to predict changes in ESs supply and demand, and their coupling mechanisms, under one baseline scenario and three stakeholder‐defined LULC change scenarios (developed, planning, policy) in Shanghai municipality, China. The results suggest that the policy scenario could significantly increase ESs supply and restore degraded urban areas, but would not guarantee that supply meets demand for four key ESs tested: water retention, particulate matter removal, carbon sequestration, and recreation. However, the policy scenario significantly reduced the shortfalls and spatial mismatches in water retention, particulate matter removal and recreation services, and also greatly restored deficit areas for all four ESs. This is valuable scientific evidence that ESs supply and demand information can be incorporated into urban land management planning in a spatially explicit manner, in order to control or prevent future potential land degradation.
Morphological and Electronic Properties of Poly(ethylene glycol)/RAMEB Polyrotaxane and Polypyrrole Supramolecular Networks
Authors: Resmerita Ana‐Maria , Asandulesa Mihai , Farcas Aurica
Published: March 2020

The effect of 10 wt% polypyrrole (PPy) incorporation on the evolution of conductivity, dielectric constant, and dielectric loss by varying the temperature and frequency of amine‐terminated poly(ethylene glycol)/randomly methylated β‐cyclodextrins (PEGBA/RAMEB) polyrotaxane cross‐linked with 1,6‐hexamethylene diisocyanate is reported. This composite material shows an enhanced dielectric constant value of 25.6 (at 10 Hz) compared with 8.3 of the pure cross‐linked PEGBA/RAMEB polyrotaxane. The values of the dielectric constant are consistent with the dielectric loss and conductivity results. The composite material shows that the direct current conductivity (σDC) at lower temperature is independent of frequency. In comparison, at higher temperature, σDC is dependent on frequency, denoting that the conductivity of the composite material is a thermally activated process. Moreover, the presence of PPy significantly influences the morphology of the cross‐linked PEGBA/RAMEB polyrotaxane. Addition of PPy into PEGBA/RAMEB material seems to be very attractive and should provide an opportunity to obtain desirable electronic properties.
Insights into gene regulation of the halovirus His2 infecting Haloarcula hispanica
Authors: Lee Sonny T. M. , Ding Jiun‐Yan , Chiang Pei‐Wen , Dyall‐Smith Mike , Tang Sen‐Lin
Published: March 2020

Gene expression in Haloarcula hispanica cells infected with the gammapleolipovirus His2 was studied using a custom DNA microarray. Total RNA from cells sampled at 0, 1, 2, 3, and 4.5 hr postinfection was reverse‐transcribed into labeled cDNA and hybridized to microarrays, revealing temporal and differential expression in both host and viral genes. His2 gene expression occurred in three main phases (early, middle, and late), and by 4.5 hr p.i. the majority of genes were actively transcribed, including those encoding the major structural proteins. Eighty host genes were differentially regulated ≥twofold postinfection, with most of them predicted to be involved in transport, translation, and metabolism. Differentially expressed host genes could also be grouped into early‐, middle‐, and late‐expressed genes based on the timing of their up‐ and downregulation postinfection. The altered host transcriptional pattern suggests regulation by His2 infection, which may reprogram host metabolism to facilitate its own DNA replication and propagation. This study enhances the characterization of many hypothetical viral genes and provides insights into the interaction between His2 and its host.
Welfare‐improving cooperation with a consumer‐friendly multiproduct corporation
Authors: García Arturo , Leal Mariel , Lee Sang‐Ho
Published: March 2020

We consider a multiproduct corporation that adopts consumer‐friendly activities and cooperates with single‐plant firms for improving welfare. We show that full cooperation is socially beneficial if products are strong complements, whereas partial cooperation with higher consumer‐friendly activities is beneficial if products are substitutes. We also examine a sequential choice game of endogenous cooperation in which the multiproduct corporation can induce (partial or full) cooperation and show that our findings are still consistent at equilibrium. We finally compare different ownership of the single‐plant firms and find that foreign ownership decreases the benefits of cooperation.
On the convergence of nonstationary column‐oriented version of algebraic iterative methods
Authors: Karimpour Mehdi , Nikazad Touraj
Published: March 2020

Recently, Elfving, Hansen, and Nikazad introduced a successful nonstationary block‐column iterative method for solving linear system of equations based on flagging idea (called BCI‐F). Their numerical tests show that the column‐action method provides a basis for saving computational work using flagging technique in BCI algorithm. However, they did not present a general convergence analysis. In this paper, we give a convergence analysis of BCI‐F. Furthermore, we consider a fully flexible version of block‐column iterative method (FBCI), in which the relaxation parameters and weight matrices can be updated in each iteration and the column partitioning of coefficient matrix is allowed to update in each cycle. We also provide the convergence analysis of algorithm FBCI under mild conditions.
Role of blogging in perceived learning and satisfaction of students
Authors: Khan Barkat Ullah , Wei Song , Shah Syed Nadir Ali , Gul Rabia , Ullah Shahid , Mehmood Shafaqat , Asma
Published: March 2020

The contemporary smart concepts of education signify a heavy role of blogging tools in digital learning environments that have a substantial effect on students' learning and satisfaction. This study aims to analyze the influence of students' four perceptions about blogging that is, perception of digital technology (PDT), perceptions of teaching and learning (PTL), perceptions of previous blogging experience (PBE), and perceived usefulness of blogging (PUB) on the frequency of blogging and then assesses the impact of the frequency of blogging on perceived satisfaction as well as perceived learning of students. For this purpose, the researchers conducted a quantitative study with a positivist approach in which the data were collected from 350 students in Anhui Province, China to conduct analysis of the proposed relationships. The results of the current study suggest that there is a positive impact of PDT, PTL, PBE and PUB on the frequency of blogging. It means that the positive perceptions of students towards digital technology, teaching and learning, previous bogging experience and usefulness of blogging result in higher frequency and use of blogging activity. It further indicates that the high frequency of blogging has ultimately a positive impact on perceived satisfaction and perceived learning. The discussion and findings of the current study have useful implications for theory and practice because they provide empirical evidence and theoretical guidelines about the role of blogging in perceived learning and satisfaction.
Cherry Picking with Synthetic Controls
Authors: Ferman Bruno , Pinto Cristine , Possebom Vitor
Published: March 2020

We evaluate whether a lack of guidance on how to choose the matching variables used in the Synthetic Control (SC) estimator creates specification‐searching opportunities. We provide theoretical results showing that specification‐searching opportunities are asymptotically irrelevant if we restrict to a subset of SC specifications. However, based on Monte Carlo simulations and simulations with real datasets, we show significant room for specification searching when the number of pre‐treatment periods is in line with common SC applications, and when alternative specifications commonly used in SC applications are also considered. This suggests that such lack of guidance generates a substantial level of discretion in the choice of the comparison units in SC applications, undermining one of the advantages of the method. We provide recommendations to limit the possibilities for specification searching in the SC method. Finally, we analyze the possibilities for specification searching and provide our recommendations in a series of empirical applications.
Color tuning in Cu(In,Ga)Se2 thin‐film solar cells by controlling optical interference in transparent front layers
Authors: Cho Dae‐Hyung , Lee Woo‐Jung , Kim Myeong‐Eon , Shin Byungha , Chung Yong‐Duck
Published: March 2020

Aesthetic factors such as colorization in harmony with the surrounding environment are becoming important in the field of applied photovoltaics. Therefore, there exists a need to realize colors in solar cells, with minimum additional cost and efficiency loss. We tuned the color of Cu(In,Ga)Se2 thin‐film solar cells by controlling the optical interference between the sputtered Zn(O,S) buffer layer and indium tin oxide (ITO) transparent electrode layer, which are intrinsic components of the solar cell device, without any additional process and/or material. The nontoxic Cd‐free buffer layer was prepared in consideration of the environmental factor. In order to minimize the degradation of the photovoltaic performance of the solar cell, the experiment was conducted within the thickness (optical path length) of the Zn(O,S) and ITO transparent front layers, which affected the solar cell performance more optically and less electrically. As the antireflection coating thickness increased, the solar cell was calculated to have a wider color range, lower luminosity, and lower JSC loss. Relatively even efficiencies were obtained with a wide color range.
Optical emission spectra of microwave discharge in different liquid hydrocarbons
Authors: Lebedev Yuri A. , Shakhatov Viatcheslav A.
Published: March 2020

Emission spectra of microwave discharge in liquid hydrocarbons (hexane (C6H14), n‐heptane (С7Н16), decane (С10Н22), pentadecane (C15H32), cyclohexane (С6Н12), toluene (С6Н5–СН3), ortho‐xylene (С6Н5–(СН3)2), and petroleum solvent nefras S2 80/120 [mixture of light hydrocarbons with boiling temperature ranging between 33°C and 205°C]) were studied in the range of wavelength 200–700 nm. The pressure above the surface of the liquid was equal to the atmospheric pressure. It was shown that in the spectra measured in aromatic hydrocarbons (toluene and ortho‐xylene) the sequence of the Swan band with  = 0 was overlapped with the molecular emission band with a maximum at 511 nm never observed before. Analysis of known data allowed us to hypothesize that this emission can be attributed to the emission of linear carbon cluster C5 . This cluster was previously observed only in absorption. Rotational temperatures determined by modeling of the sequence Δυ = −1 of the Swan band were equal to 2,000 ± 300 K for all studied hydrocarbons.
Design and characterization of a plasma chamber for improved radial and axial film uniformity
Authors: Radjef Racim , Jarvis Karyn , Fox Bronwyn L. , McArthur Sally L.
Published: March 2020

Film uniformity is an issue in many deposition processes, especially in substrates with elongated lateral dimensions such as fibers. In this study, a plasma chamber was designed with dual electrodes to improve the uniformity of plasma polymer films. Plasma‐polymerized acrylic acid films were deposited via single‐electrode or double‐electrode configurations onto silicon wafer pieces placed at the center of the chamber to mimic the potential position of a fiber. A radial and spatial map of film chemistry and thickness throughout the chamber was determined which demonstrated improved radial uniformity and film stability using the dual‐electrode configuration, thus highlighting the importance of spatial characterization when designing a reactor for the coating of three‐dimensional objects such as fibers.
Enhancing the Performance of an HTPE Binder by Adding a Novel Hyperbranched Multi‐Arm Azide Copolyether
Authors: Wen Xiaomu , Zhang Guangpu , Chen Keke , Yuan Shen , Luo Yunjun
Published: March 2020

Modern composite solid propellants must exhibit excellent mechanical properties together with high energy outputs, and the binder system plays a vital role in establishing these characteristics. In the present work, varying proportions of a novel hyperbranched multi‐arm azide copolyether (POG) were combined with a hydroxyl‐terminated polyether (HTPE) to prepare crosslinked elastomeric binders. The compatibility of the POG and HTPE was demonstrated before a series of HTPE/POG blend binders were prepared based on a urethane reaction using hexamethylene diisocyanate (HMDI) as the curing agent. The mechanical properties of HTPE/POG/HMDI elastomers were found to be superior to those of traditional HTPE/N100 crosslinked binders as a result of the formation of a hyperbranched crosslink structure. Evaluations of the local motions of polymers chains and parameters related to the cured network structure demonstrated the advantages of introducing the hyperbranched POG. Hydrogen bonding in the HTPE/POG/HMDI binder was investigated and the results confirmed that these elastomers also benefited from hydrogen bonding, as well as the entanglement and interpenetration of molecular chains. Decomposition behavior was studied by thermogravimetric analysis, differential thermogravimetry and differential scanning calorimetry, and the new binders exhibited good thermal stability and superior energetic performance that could potentially meet the requirements for military applications.
Gradient Denitration Strategy Eliminates Phthalates Associated Potential Hazards During Gun Propellant Production and Application
Authors: Li Shiying , Tao Zhongan , Ding Yajun , Liang Hao , Zhao Xianzheng , Xiao Zhongliang , Li Chunzhi , Ou Jiangyang
Published: March 2020

Phthalates, which often have to be used as deterrents during gun propellants production for realizing progressive burning, are widely believed to be harmful to human and the environment. Meanwhile, phthalates also generate much smoke during propellant combustion, thus, lowering firing accuracy and exposing positions, which may bring risk. To avoid phthalates usage during propellants production, this work, for the first time, reported the employment of “gradient denitration” strategy to prepare nitrocellulose‐based gun propellant without the addition of any phthalate deterrents. The successful preparation of gradiently denitrated gun propellant (GDGP) was supported by FT‐IR, Raman spectroscopy and FESEM equipped with energy‐dispersive X‐ray spectroscopy (EDS), as evidenced by the gradiently increased content of nitrogen and nitrate group from the surface to the core of GDGP. Such a denitration process, without any hazardous phthalates deterrents addition, could also realize the good progressive burning performance of the gun propellant, as confirmed by closed bomb test and ballistic gun test. Meanwhile, both theoretical calculation and weapon muzzle smoke test also demonstrated the lowering of smoke generation during propellant combustion. This phthalates‐free strategy paves a new way to eliminate potential hazards associated with phthalates during traditional gun propellant production and application.
Molecularly Imprinted Polymer‐based Novel Electrochemical Sensor for the Selective Detection of Aldicarb
Authors: Saxena Suryansh , Lakshmi Garimella B. V. S. , Chauhan Deepika , Solanki Pratima R.
Published: March 2020

The development of a novel, molecularly imprinted polymer (MIP), based on polyaniline nanofibers (PANInfs) for the electrochemical detection of aldicarb (Ald), is reported. PANInfs are synthesized by the simple interfacial polymerization method with and without the presence of Ald. A part of the PANInfs containing Ald (MIP‐Ald) is dispersed in deionized (DI) water and sonicated to remove Ald and obtain MIP. The MIP, bare PANInfs (non‐imprinted polymer or [NIP]), and the nonsonicated polymer (MIP‐Ald) are separately drop cast onto hydrolyzed indium tin oxide (ITO)‐coated glass. All these three types of electrodes are characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and cyclic voltammetry (CV) techniques to understand their structure, morphology, and successful synthesis of the desired compounds. The electrochemical detection of Ald is conducted using differential pulse voltammetry (DPV). This MIP‐based sensor is able to detect Ald in the range of 50–80 nM with a limit of detection 500 pM L−1, having a sensitivity of 6.83 ± 0.09 μA nM−1 cm−2, making it an ideal candidate for Ald detection. This method is adapted to synthesize MIPs of other pesticides by which the cost and the detection time is reduced considerably.
Internal Fields in Multilayer WS2/MoS2 Heterostructures Epitaxially Grown on Sapphire Substrates
Authors: Kim Bora , Kim Jayeong , Tsai Po-Cheng , Kwon Soyeong , Kim Eunah , Yoon Seokhyun , Lin Shih-Yen , Kim Dong-Wook
Published: March 2020

In conventional 3D heterostructures, a gradual potential gradient in constituent layers and an abrupt potential discontinuity at heterointerfaces can appear. Studies of the electrostatic potential in 2D heterostructures require careful characterizations and analyses because the 2D materials have distinct physical characteristics compared with their 3D counterparts. Herein, three kinds of samples are prepared using sulfurization of metal layers on single‐crystalline sapphire substrates: WS2, MoS2, and WS2/MoS2. The surface potential (VS) of the samples is measured using Kelvin probe force microscopy. The light‐induced VS change in the stand‐alone trilayer (3L‐) WS2 (−63 mV) is much more notable than that in the 3L‐WS2/3L‐MoS2 heterostructure (−12 mV). In contrast, the light‐induced VS change in the stand‐alone 3L‐MoS2 is positive and very large (≈200 mV). To explain these results, the potential and internal field distributions are proposed for both the stand‐alone (WS2 and MoS2) and heterostructure (WS2/MoS2) samples. The polarity and magnitude of the internal field depend on the electronic interaction and screening from neighboring 2D layers and underlying substrates. Relative peak shifts of the Raman spectra of the samples are obtained and discussed, with consideration of the internal field effects.
Changing the Electronic and Magnetic Properties of Monolayer HfS2 by Doping and Vacancy Defects: Insight from First‐Principles Calculations
Authors: Ali Anwar , Zhang Jian-Min , Muhammad Iltaf , Wei Xiu-Mei , Ahmad Iqtidar , Rehman Majeed Ur
Published: March 2020

The effects of various vacancies and group‐VIB and VIIB transition metal substitutional doping on the structural, electronic, and magnetic properties of monolayer HfS2 are studied by first‐principles calculations. The results show that pristine monolayer HfS2 is a nonmagnetic semiconductor; it becomes a metal on creating a single V1Hf or V1S vacancy, whereas it is still a semiconductor on creating V1Hf+1S divacancy or V1Hf+2S trivacancy. The V1Hf single vacancy and V1Hf+1S divacancy induce magnetic moments of 3.265 and 2.000 μB, respectively, whereas the V1S single vacancy and V1Hf+2S trivacancy do not induce any magnetic moments. One of the group‐VIB and VIIB transition metal atoms substituting for one Hf atom in the monolayer HfS2 induces magnetic moments of about 2.000 and 3.000 μB, respectively. Furthermore, the spin‐polarized band structures show that the Cr‐doped monolayer HfS2 is a magnetic metal, whereas the Mn‐, Tc‐, and Re‐doped monolayer HfS2 are magnetic semiconductor. The Mo‐ and W‐doped monolayer HfS2 are magnetic half metal with wide spin‐down bandgaps of 0.975 and 1.074 eV, respectively, and thus can be used in nanoelectronics and spintronics devices.
A Facile Air‐Retreatment Strategy for Efficient Inverted Perovskite Solar Cells
Authors: Dai Zhongjun , Xiong Jian , Zhan Shiping , Fan Baojin , Zhao Qian , Liu Weizhi , He Zhen , Yang Bingchu , Yang Junliang , Xue Xiaogang , Zhang Jian
Published: March 2020

A simple air‐retreatment strategy is proposed to improve the performance of the inverted perovskite solar cells (PSCs). This air‐retreatment impact on the physical properties and corresponding performance of the devices is systematically studied. The results show that the grain size of perovskite films is enhanced by this method, and the high quality of MAPbI3 films is successfully prepared. The average grain size of 3.91 μm and the largest grain size exceeding 9 μm are achieved, and the trap states are reduced from 4.05 × 1016 cm−3 to 1.60 × 1016 cm−3. Benefitted by the relatively larger grain size, lower trap density, and higher crystallinity, a high power conversion efficiency (PCE) of 18.44% and negligible hysteresis are obtained. This air‐retreatment strategy has great potential in the large‐scale, low‐temperature preparation of efficient and stable PSCs.
Evaluating the GECCO3 1948–2018 ocean synthesis – a configuration for initializing the MPI‐ESM climate model
Authors: Köhl Armin
Published: March 2020

The paper describes an update of the GECCO (German contribution to the Estimating the Circulation and Climate of the Ocean project) ocean synthesis, now in its version 3, and provides an evaluation of the results with assimilated and independent data. GECCO3 covers the 71‐year period 1948–2018 and differs from its predecessor by returning to a single assimilation window instead of partitioning the period in 5‐year‐long overlapping windows which was previously necessary to yield convergence. A solution to the convergence problem is presented. GECCO3 is intended to be used for the initialization of coupled climate models and is configured for the higher‐resolution version of the earth system model (MPI‐ESM) developed at the Max Planck Institute for Meteorology. It uses the bathymetry and grid of the MPI‐ESM with quasi‐uniform resolution of 0.4°, thereby providing the first global eddy‐permitting synthesis based on the adjoint method. The synthesis additionally features the estimation of various mixing parameters and can regionally choose between explicit or parametrized eddy fluxes. Except for the altimeter data in tropical regions, GECCO3 is in better agreement with the assimilated data than GECCO2. The improvements relative to the in situ data partly result from the much larger amount of Argo data, which show lower model–data differences. Global heat content changes are in good agreement with recent estimates, but show uptake almost exclusively in the top 700 m. An alternative version of GECCO3, created by starting from different first‐guess control parameters, was used to evaluate the uncertainty of the estimated parameters and state due to lack of convergence. This estimate suggests a large uncertainty related to the uptake of heat into the lower layers, while estimates of mean meridional transport of heat and freshwater are not affected.
The potential use of operational radar network data to evaluate the representation of convective storms in NWP models
Authors: Stein Thorwald H. M. , Scovell Robert W. , Hanley Kirsty E. , Lean Humphrey W. , Marsden Nicola H.
Published: March 2020

Operational forecasting centres increasingly rely on convection‐permitting NWP simulations to assist in their forecasting of convective events. The evaluation of upgrades in the underlying NWP modelling system normally happens through routine verification using traditional metrics on two‐dimensional fields, such as gridded rainfall data. Object‐ and process‐based evaluation can identify specific physical mechanisms for model improvement, but such evaluation procedures normally require targeted and expensive field campaigns. Here, we explore the potential use of the UK operational radar network observations and its derived 3D composite product for evaluating the representation of convective storms in the Met Office Unified Model. A comparison of the 1 × 1 × 0.5 km 3D radar composites against observations made with the research‐grade radar at Chilbolton in the southern UK indicates that the 3D radar composite data can reliably be used to evaluate the morphology of convective storms. The 3D radar composite data are subsequently used to evaluate the development of convective storms in the Met Office Unified Model. Such analysis was previously unavailable due to a lack of 3D radar data of high temporal frequency. The operational nature of the UK radar data makes these 3D composites a valuable resource for future studies of the initiation, growth, development, and organisation of convective storms over the
UK.
Remaining useful life prediction via a variational autoencoder and a time‐window‐based sequence neural network
Authors: Su Chun , Li Le , Wen Zejun
Published: March 2020

The prediction of remaining useful life (RUL) has attracted much attention, and it is also a key section for predictive maintenance. In this study, a novel hybrid deep learning framework is proposed for RUL prediction, where a variational autoencoder (VAE) and time‐window‐based sequence neural network (twSNN) are integrated. Among it, VAE is used to extract the hidden and low‐dimensional features from the raw sensor data, and a loss function is designed to extract useful data features; by using a sliding time window, twSNN can predict RUL dynamically; meanwhile, it can simplify the network architecture in the time dimension. Furthermore, to achieve higher performance on various failure conditions, long short‐term memory (LSTM) cell and convolutional LSTM (ConvLSTM) cell are designed for twSNN respectively. A case study is completed with a dataset of aircraft turbine engines. It is found that the proposed frameworks with LSTM cell and ConvLSTM cell have better performance on both single failure mode and multiple failure modes. The results also show that the prediction accuracy is averagely improved by 6.65% for single failure mode and 15.05% for multiple failure modes respectively.
Structures, g‐tensors, and hyperfine coupling constants of L‐α‐alanine radicals in radiation dosimetry: An ab initio molecular dynamics simulation study
Authors: Janbazi Mehdi , Azar Yavar T. , Ziaie Farhood , Ghandi Khashayar , Matta Chérif F. , Shadman Lakmehsari Muhammad
Published: March 2020

Alanine is used as a transfer standard dosimeter for gamma ray and electron beam calibration. An important factor affecting its dosimetric response is humidity which can lead to errors in absorbed dose calculations. Ab initio molecular dynamics calculations were performed to determine the environmental effects on the electron paramagnetic resonance (EPR) parameters of L‐α‐alanine radicals in acidic and alkaline solutions. A new result, not dissimilar to the closed‐shell amino acid molecule alanine, is that the non‐zwitterionic form of the alanine radical is the stable form in the gas phase while the zwitterionic neutral alanine radical is not a stable structure in the gas phase. Geometric and EPR parameters of radicals in both gas and solution phases are found to be dependent on hydrogen bonding of water molecules with the polar groups and on dynamic solvation. Calculations on the optimized free radicals in the gas phase revealed that for the neutral radical, hydrogen bonding to water molecules drives a decrease in the magnitudes of g‐tensor components g
xx and g
yy without affecting neither g
zz component nor the hyperfine coupling constants (HFCCs). The transfer from the gas to solution phase of the alanine radical anion is accompanied with an increase in the spin density on the carboxylic group's oxygen atoms. However, for the neutral radical, this transfer from gas to solution phase is accompanied with the decrease in the spin density on oxygen atoms. Calculated isotropic HFCCs and g‐tensor of all radicals are in good agreement with experiment in both acidic and alkaline solutions.
In search of the smallest boroxol‐type heterocyclic ring system: Planar hexagonal B3S3+ cluster with double 6π/2σ aromaticity
Authors: Zhang Li‐Juan , Feng Lin‐Yan , Bian He , Pei Ling , Li Da‐Zhi , Zhai Hua‐Jin
Published: March 2020

Boroxol (B3O3) rings and relevant hexagonal B3S3 structural blocks are ubiquitous in boron oxide/sulfide glasses, crystals, and high‐temperature liquids. However, the isolation of an ultimate heterocyclic B3O3 or B3S3 cluster in the free‐standing form, with as few as six atoms, has been unsuccessful so far. We report on computational design of the simplest case of such a system: the highly symmetric D3h B3S3+ (1A1′) cluster. It is the well‐defined global minimum on the potential energy surface, following global searches and electronic structure calculations at the B3LYP and single‐point CCSD(T) levels. Chemical bonding analysis reveals an ideal system with skeleton Lewis BS σ single bonds and unique double 6π/2σ aromaticity, which underlies its stability. The cluster turns out to be an inorganic analog of the 3,5‐dehydrophenyl cation, a typical double π/σ aromatic system. It offers an example for chemical analogy between boron‐based heterocyclic clusters and aromatic hydrocarbons. Double π/σ aromaticity is also a new concept in heterocyclic boron clusters. Previous systems such as borazine, boroxine, and boronyl boroxine only deal with π aromaticity as in benzene.
Nanostructuring Co3O4 to Tune Capacitive Behaviors: From Low to High Dimensions
Authors: Yang Pingping , Wu Fengkai , Wang Liuliu , Chen Xiaoying , Xie Jiale
Published: March 2020

Pseudocapacitance is mainly contributed by fast surface‐controlled reactions. However, the effect of nanostructures on the capacitive behaviour has not been systematically studied yet. In this work, we synthesize different Co3O4 nanostructures with the same crystal structure and exposed clean crystal planes that include 1D nanowire, 2D nanosheet, 3D rambutan‐like and hierarchical structures, ranging from low to high dimensions. It is discovered the specific capacitance of Co3O4 materials follows the order of 1D nanowire > hierarchical structure > 2D nanosheet > 3D rambutan‐like structure while the electron transfer resistance is 1D nanowire < 2D nanosheet < hierarchical structure < 3D rambutan‐like structure. Under the same electrochemistry, results suggest the pseudocapacitance is not simply dependent on the surface area offered by the nanostructure, but relies on the conductivity, accessibility, diffusion rate and reactivity of the electrode. 1D nanostructure can render the highest reactant accessibility, fastest electron transfer and largest diffusion rate, thus achieving the highest specific pseudocapacitance.
Egg Yolk Biomass Derived N‐Doped Ordered Mesoporous Carbon: Highly Robust Heterogeneous Organocatalyst for One‐Pot Deacatalization‐Knoevenagel Reaction
Authors: Nadem Sahar , Vahdati‐Khajeh Saleh , Eftekhari‐Sis Bagher
Published: March 2020

A novel and facile synthetic route for CMK‐3 type N‐rich ordered mesoporous carbon from cheap egg yolk biomass as a carbon precursor (EYCP) and SBA‐15 as a hard structure directing agent has been developed. To obtain a well‐ordered material, carbonization temperature was investigated. The N2 adsorption‐desorption analysis proved that the synthetic mesoporous carbon material at 500 °C is highly ordered, with high surface area of 226 m2 g−1, and nitrogen content of 6.2% was determined by CHN analysis. Corresponding mesoporous materials were examined as bifunctional acid‐base organocatalysts in a one‐pot tandem deacetalization‐Knoevenagel reaction. Results showed that the modified carbon material which was synthesized at 500 °C exhabited high nitrogen content and reactivity in one‐pot deacetalization‐Knoevenagel reaction. Carboxylic acid and pyridinic nitrogen groups of carbon material play as a bifunctional acid and base catalyst.