bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular fingerprint and machine learning to accelerate design of high‐performance homochiral metal–organic frameworks
Authors: Qiao Zhiwei , Li Lifeng , Li Shuhua , Liang Hong , Zhou Jian , Snurr Randall Q. 
Published: June 2021

AbstractComputational screening was employed to calculate the enantioseparation capabilities of 45 functionalized homochiral metal–organic frameworks (FHMOFs), and machine learning (ML) and molecular fingerprint (MF) techniques were used to find new FHMOFs with high performance. With increasing temperature, the enantioselectivities for (R,S)‐1,3‐dimethyl‐1,2‐propadiene are improved. The “glove effect” in the chiral pockets was proposed to explain the correlations between the steric effect of functional groups and performance of FHMOFs. Moreover, the neighborhood component analysis and RDKit/MACCS MFs show the highest predictive effect on enantioselectivities among the four ML classification algorithms with nine MFs that were tested. Based on the importance of MF, 85 new FHMOFs were designed, and a newly designed FHMOF, NO2‐NHOH‐FHMOF, with high similarity to the optimal MFs achieved improved chiral separation performance, with enantioselectivities of 85%. The design principles and new chiral pockets obtained by ML and MFs could facilitate the development of new materials for chiral separation.
Universal Singlet‐Triplet Qubits Implemented Near the Transverse Sweet Spot
Authors: Xie Wen‐Xin , Zhang Chengxian , Xue Zheng‐Yuan 
Published: June 2021

AbstractThe key to realizing fault‐tolerant quantum computation for singlet‐triplet (ST) qubits in semiconductor double quantum dot (DQD) is to operate both the single‐ and two‐qubit gates with high fidelity. The feasible way includes operating the qubit near the transverse sweet spot (TSS) to reduce the leading order of the noise, as well as adopting the proper pulse sequences which are immune to noise. The single‐qubit gates can be achieved by introducing an AC drive on the detuning near the TSS. The large dipole moment of the DQDs at the TSS has enabled strong coupling between the qubits and the cavity resonator, which leads to two‐qubit entangling gates. When operating in the proper region and applying modest pulse sequences, both single‐ and two‐qubit gates have fidelity higher than 99%. The results in this paper suggest that taking advantage of the appropriate pulse sequences near the TSS can be effective to obtain high‐fidelity ST qubits.
Synthesis of N‐Heterocycles via Oxidant‐Free Dehydrocyclization of Alcohols Using Heterogeneous Catalysts
Authors: Sun Kangkang , Shan Hongbin , Lu Guo‐Ping , Cai Chun , Beller Matthias 
Published: June 2021

AbstractN‐Heterocycles, such as pyrroles, pyrimidines, quinazolines, and quinoxalines, are important building blocks for organic chemistry and the fine‐chemical industry. For their synthesis, catalytic borrowing hydrogen and acceptorless dehydrogenative coupling reactions of alcohols as sustainable reagents have received significant attention in recent years. To overcome the problems of product separation and catalyst reusability, several metal‐based heterogeneous catalysts have been reported to achieve these transformations with good yields and selectivity. In this Minireview, we summarize recent developments using both noble and non‐noble metal‐based heterogeneous catalysts to synthesize N‐heterocycles from alcohols and N‐nucleophiles via acceptorless dehydrogenation or borrowing hydrogen methodologies. Furthermore, this Minireview introduces strategies for the preparation and functionalization of the corresponding heterogeneous catalysts, discusses the reaction mechanisms and the roles of metal electronic states, and the influence of support Lewis acid–base properties on these reactions.
Photoelectron Circular Dichroism in the Photodetachment of Amino Acid Anions
Authors: Krüger Peter , Weitzel Karl‐Michael 
Published: June 2021

AbstractThe chirality of chemical compounds is of undisputed importance in science and technology. In particular with respect to pharmacological application most molecules of interest cannot be accessed by the powerful techniques developed in recent years for gas phase analytes. Here, we demonstrate that the combination of electrospray ionization (ESI) with the detection of photoelectron circular dichroism (PECD) provides access to chirality information applicable to molecular materials with negligible vapor pressure, for example, amino acids. To this end, glutamic acid and 3,4‐dihydroxyphenylalanine (DOPA) have been electrosprayed into the source of a chirality spectrometer, where photodetachment is enforced and the PECD is detected. The technique can be expected to be conceptually applicable to all chemical systems with chirality based on molecular properties.
Effects of shell powder size and content on the properties of polycaprolactone composites
Authors: Weng Fangqing , Zhang Peirui , Koranteng Ernest , Zhang Yu , Wu Qiangxian , Zeng Guoping 
Published: June 2021

AbstractIn this work, the effects of particle size and content of clam shell powder (CSP) on the mechanical properties and microstructure of clam shell powder‐polycaprolactone (CSP‐PCL) composites were studied. Accordingly, shell powder with particle size of 50, 100, 200, and 400 meshes, and CSP content of 30, 40, 50, and 60 wt%, respectively, were utilized to prepare CSP‐PCL composites. The interface structure and properties of CSP‐PCL composites were investigated by infrared spectroscopy (IR), X‐Ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis (TGA), and tensile tests. The results showed that the tensile properties of the composite materials correlated with the particle size and content of the filler. For instance, the smaller the particle size of CSP (400 meshes), the better the tensile properties of the composite. What is more, the tensile properties of the composites were negatively affected by the amount of CSP content. In terms of microstructure, shell powder particles could disperse uniformly in the PCL matrix, and the CSP‐PCL composites with polyurethane prepolymer as compatibilizer gave a better compatibility.
Photosensitive acrylates containing bio‐based epoxy‐acrylate soybean oil for 3D printing application
Authors: Rosace Giuseppe , Palucci Rosa Raphael , Arrigo Rossella , Malucelli Giulio 
Published: June 2021

AbstractStereolithography is a 3D‐printing process that is rapidly shifting from being an expensive and limited technology to an affordable, precise, and fast method of mass production. However, most of the current resins are petroleum‐based, which makes them toxic, non‐degradable and with poor biocompatibility. In this study, a standard petroleum‐based resin containing urethane acrylate and acrylic monomers was combined with epoxy‐acrylate soybean oil (EASO), aiming to reduce its impact on the environment. Ratios varying from 10 to 50 wt% of EASO were incorporated into the commercial resin while maintaining the viscosity low, between 0.27 and 1.06 Pa s. The printed samples showed good quality and complete integration between the layers. The addition of 50 wt% of EASO increased the samples elongation at break by 108% (from 2.3% to 4.8%) and decreased the contact angle by 26.4% (from 72 to 53°). Moreover, the mixture showed good thermal and swelling stability and tensile strength in the range of other commercial cured systems. The addition of EASO may significantly contribute to the exploitation of greener materials, which well matches today's circular economy concept.
Contextualizing the relative importance of habitat connectivity for metapopulation persistence: A case study of a critically endangered fish
Authors: Coats Simon C. , Wilson Matthew , McIntosh Angus R. 
Published: June 2021

AbstractLocal population characteristics and habitat connectivity both have important influences on metapopulation persistence; however, the relative importance of each can vary depending on the ecological context, making it difficult to apply general ‘rules‐of‐thumb’ for conservation actions. This is particularly true in dendritic networks, where habitat connections are constrained.By constructing a metapopulation model that specifically accounts for the unique characteristics and ecological system of a target species, the relative influence of local population characteristics and habitat connectivity on metapopulation persistence can be assessed more accurately.This modelling approach was used to improve conservation outcomes for the Canterbury mudfish (kо̄waroNeochanna burrowsius), a critically endangered and poorly understood species that is endemic to the Canterbury Plains of Aotearoa/New Zealand. A spatially structured metapopulation model ofN. burrowsiuswas used to investigate the relationship between habitat patch connectivity, rate of population growth as limited by habitat quality (rconditional), and metapopulation persistence.N. burrowsiusmetapopulation persistence increased most strongly under increases inrconditional, but increases in habitat connectivity also had positive effects (94% metapopulation persistence for highly connected networks vs. 39% metapopulation persistence for poorly connected networks whererconditional = 1.3).Although rates of population growth were more influential than increases in habitat connectivity in this case study, both will be important to consider for effectively allocating conservation resources for metapopulations in dendritic networks, depending on what managers could effectively manipulate to enhance metapopulation persistence.
Anticancer activities, structure–activity relationship, and mechanism of action of 12‐, 14‐, and 16‐membered macrolactones
Authors: Wang Ruo 
Published: June 2021

AbstractCancer remains one of the major causes of death worldwide despite the encouraging breakthroughs in the discovery of novel chemotherapeutic agents in recent years. The development of new effective anticancer candidates still represents a challenging endeavor due to the severe anticancer demands and the emergence of drug‐resistant, especially multidrug‐resistant, cancers. Macrolactones could regulate multiple signaling pathways in cancer cells and demonstrated potential anticancer effects, including inhibition of proliferation, metastasis, and angiogenic activity. Accordingly, macrolactones possess excellent efficacy against both drug‐sensitive and drug‐resistant cancer cells, and the rational design of macrolactones may provide valuable therapeutic interventions for cancers. The purpose of this review is as follows: (1) outline the recent advances made in the development of 12‐, 14‐, and 16‐membered macrolactones with anticancer potential; (2) summarize the structure–activity relationship; and (3) discuss their anticancer mechanisms.
Lexical data augmentation for sentiment analysis
Authors: Xiang Rong , Chersoni Emmanuele , Lu Qin , Huang Chu‐Ren , Li Wenjie , Long Yunfei 
Published: June 2021

AbstractMachine learning methods, especially deep learning models, have achieved impressive performance in various natural language processing tasks including sentiment analysis. However, deep learning models are more demanding for training data. Data augmentation techniques are widely used to generate new instances based on modifications to existing data or relying on external knowledge bases to address annotated data scarcity, which hinders the full potential of machine learning techniques. This paper presents our work using part‐of‐speech (POS) focused lexical substitution for data augmentation (PLSDA) to enhance the performance of machine learning algorithms in sentiment analysis. We exploit POS information to identify words to be replaced and investigate different augmentation strategies to find semantically related substitutions when generating new instances. The choice of POS tags as well as a variety of strategies such as semantic‐based substitution methods and sampling methods are discussed in detail. Performance evaluation focuses on the comparison between PLSDA and two previous lexical substitution‐based data augmentation methods, one of which is thesaurus‐based, and the other is lexicon manipulation based. Our approach is tested on five English sentiment analysis benchmarks: SST‐2, MR, IMDB, Twitter, and AirRecord. Hyperparameters such as the candidate similarity threshold and number of newly generated instances are optimized. Results show that six classifiers (SVM, LSTM, BiLSTM‐AT, bidirectional encoder representations from transformers [BERT], XLNet, and RoBERTa) trained with PLSDA achieve accuracy improvement of more than 0.6% comparing to two previous lexical substitution methods averaged on five benchmarks. Introducing POS constraint and well‐designed augmentation strategies can improve the reliability of lexical data augmentation methods. Consequently, PLSDA significantly improves the performance of sentiment analysis algorithms.
Gravitational radiation‐reaction driven instabilities in rotating neutron stars
Authors: Lin Zikun , Bratton Eric , Weber Fridolin , Orsaria Milva G. , Ranea‐Sandoval Ignacio F. 
Published: June 2021

AbstractWe investigate in this work two different types of instabilities that set limits on the rotation rates of neutron (compact) stars. The first one is that caused by rotation at the Kepler frequency, at which mass shedding at the star's equator sets in. The second limit is set by instabilities driven by the growth of gravitational radiation‐reaction (GRR) driven ‐modes of order , which are moderated by shear and bulk viscosity. The calculations are performed for two relativistic models for the nuclear equation of state, DD2 and ACB4. The latter accounts for a phase transition that gives rise to the existence of so‐called mass‐twin compact stars. Our results confirm that the stable rotation periods of cold neutron stars are determined by the modes and that these modes are excited at rotation periods between 1 and 1.4 ms (20–30% above the Kepler periods of these stars). The situation is reversed in hot neutron stars where bulk viscosity damps the GRR modes, pushing the excitation period of the ‐mode instability to values below the Kepler period. For cold mass‐twin compact stars, we find that the instability sets in at rotation periods between 0.8 and 1 ms (25–30% below the Kepler period). This feature may allow one to distinguish conventional neutron stars from their possibly existing mass‐twin counterparts observationally, provided the ‐mode instability, which is expected to compete with the ‐mode instability, sets the limit on stable rotation of compact stars.
An ion‐paired moxifloxacin nanosuspension eye drop provides improved prevention and treatment of ocular infection
Authors: Josyula Aditya , Omiadze Revaz , Parikh Kunal , Kanvinde Pranjali , Appell Matthew B. , Patel Pratikkumar , Saeed Hiwa , Sutar Yogesh , Anders Nicole , He Ping , McDonnell Peter J. , Hanes Justin , Date Abhijit A. , Ensign Laura M. 
Published: June 2021

AbstractThere are numerous barriers to achieving effective intraocular drug administration, including the mucus layer protecting the ocular surface. For this reason, antibiotic eye drops must be used multiple times per day to prevent and treat ocular infections. Frequent eye drop use is inconvenient for patients, and lack of adherence to prescribed dosing regimens limits treatment efficacy and contributes to antibiotic resistance. Here, we describe an ion‐pairing approach used to create an insoluble moxifloxacin–pamoate (MOX–PAM) complex for formulation into mucus‐penetrating nanosuspension eye drops (MOX–PAM NS). The MOX–PAM NS provided a significant increase in ocular drug absorption, as measured by the area under the curve in cornea tissue and aqueous humor, compared to Vigamox in healthy rats. Prophylactic and treatment efficacy were evaluated in a rat model of ocular Staphylococcus aureus infection. A single drop of MOX–PAM NS was more effective than Vigamox, and completely prevented infection. Once a day dosing with MOX–PAM NS was similar, if not more effective, than three times a day dosing with Vigamox for treating S. aureus infection. The MOX–PAM NS provided increased intraocular antibiotic absorption and improved prevention and treatment of ocular keratitis, and the formulation approach is highly translational and clinically relevant.
Improving antitumor immunity using antiangiogenic agents: Mechanistic insights, current progress, and clinical challenges
Authors: Li Shu‐Jin , Chen Jia‐Xian , Sun Zhi‐Jun 
Published: June 2021

AbstractCancer immunotherapy, especially immune checkpoint blockade (ICB), has revolutionized oncology. However, only a limited number of patients benefit from immunotherapy, and some cancers that initially respond to immunotherapy can ultimately relapse and progress. Thus, some studies have investigated combining immunotherapy with other therapies to overcome resistance to monotherapy. Recently, multiple preclinical and clinical studies have shown that tumor vasculature is a determinant of whether immunotherapy will elicit an antitumor response; thus, vascular targeting may be a promising strategy to improve cancer immunotherapy outcomes. A successful antitumor immune response requires an intact “Cancer‐Immunity Cycle,” including T cell priming and activation, immune cell recruitment, and recognition and killing of cancer cells. Angiogenic inducers, especially vascular endothelial growth factor (VEGF), can interfere with activation, infiltration, and function of T cells, thus breaking the “Cancer‐Immunity Cycle.” Together with immunostimulation‐regulated tumor vessel remodeling, VEGF‐mediated immunosuppression provides a solid therapeutic rationale for combining immunotherapy with antiangiogenic agents to treat solid tumors. Following the successes of recent landmark phase III clinical trials, therapies combining immune checkpoint inhibitors (ICIs) with antiangiogenic agents have become first‐line treatments for multiple solid tumors, whereas the efficacy of such combinations in other solid tumors remains to be validated in ongoing studies. In this review, we discussed synergies between antiangiogenic agents and cancer immunotherapy based on results from preclinical and translational studies. Then, we discussed recent progress in randomized clinical trials. ICI‐containing combinations were the focus of this review because of their recent successes, but combinations containing other immunotherapies were also discussed. Finally, we attempted to define critical challenges in combining ICIs with antiangiogenic agents to promote coordination and stimulate collaboration within the research community.
Studies on the Polyphenolic Composition and the Antioxidant Properties of the Leaves of Poplar (Populus spp.) Various Species and Hybrids
Authors: Pobłocka‐Olech Loretta , Głód Daniel , Jesionek Anna , Łuczkiewicz Maria , Krauze‐Baranowska Mirosława 
Published: June 2021

AbstractThe chemical composition in terms of flavonoid and salicylic compounds of leaves from 6 species and 3 hybrids of poplars (Populus) was identified with the use of TLC and HPLC‐DAD/ESI‐MS methods. Chromatographic analyses were carried out with 21 standard compounds including salicylic compounds (2), phenolic acids (3) and flavonoids (16). Moreover, on the basis of the obtained chromatographic data from the HPLC‐DAD/ESI‐MS and TLC separations, the presence of salicortin, tremulacin and chlorogenic acid was confirmed, depending on the analyzed poplar species or hybrid. The content of salicylic compounds was determined by HPLC‐UV method and expressed on salicin as free and total fraction. Total flavonoid content was determined by spectroscopic method as quercetin equivalent. Significant qualitative and quantitative differences in the chemical composition of the analyzed leaves were demonstrated. The highest concentration of flavonoids (8.02 mg/g) was found in the leaves of Populus nigra, while the highest content of salicylic compounds (47.14 mg/g) was found in the leaves of P.×berolinensis. The antioxidant and xanthine oxidase inhibition properties of extracts from poplar leaves were investigated by TLC bioautography. It has been shown that the richest set of compounds with antioxidant properties are present in the leaves of P. alba, P.×candicans and P. nigra.
Antinociceptive Activity of Compounds from the Aqueous Extract of Melampodium divaricatum
Authors: Pérez‐Vásquez Araceli , Padilla‐Mayne Sofía , Martínez Ana Laura , Calderón José S. , Macías‐Rubalcava Martha L. , Torres‐Colín Rafael , Rangel‐Grimaldo Manuel , Mata Rachel 
Published: June 2021

AbstractA decoction prepared from the aerial parts of Melampodium divaricatum showed antinociceptive and antihyperalgesic responses when tested in the formalin model in mice. From the CH2Cl2 fraction of the decoction, two non‐previously reported secondary metabolites, 3‐O‐β‐D‐glucopyranosyl‐16α‐hydroxy‐ent‐kaurane (1) and melampodiamide (2) [(2′R*,4′Z)‐2′‐hydroxy‐N‐[(2S*,3S*,4R*)‐1,3,4‐trihydroxyoctadec‐2‐yl]tetracos‐4‐enamide] were separated and characterized by spectroscopic, spectrometric, and computational techniques. The flavonoids isoquercitrin and hyperoside, which possessed noted antinociceptive properties, were obtained from the active AcOEt fraction of the decoction. The chemical composition of the essential oil of the plant was also analyzed by gas chromatography‐mass spectrometry. The major constituents were (E)‐caryophyllene, germacrene D, β‐elemene, δ‐elemene, γ‐patchoulene, and 7‐epi‐α‐selinene. Headspace solid‐phase microextraction analysis detected (E)‐caryophyllene as the main volatile compound of the plant.
An Overview of Numerical Simulations on Gas‐Solid Cyclone Separators with Tangential Inlet
Authors: Dehdarinejad Ehsan , Bayareh Morteza 
Published: June 2021

AbstractCyclone separators play a dominating role in fluid catalytic cracking, biomass pyrolysis, dedusting, demisting, heavy oil regrading, etc. Separation mechanism, pressure drop, particle size, collection efficiency, gas underflow, gas inlet velocity, particle loading, cut‐off size of particles, and gas residence time are the main cyclone performance criteria. In the present work, the particle separation theory is explained and recent developments of numerical simulations of different cyclone separators with tangential inlet are summarized. Besides, the effect of different parameters on cyclone performance is discussed and several suggestions are provided based on previous numerical simulations.
Ionization and Photofragmentation of Isolated Metalloporphyrin Cations Investigated by VUV Action Spectroscopy**
Authors: Schubert Kaja , Schwob Lucas , Dörner Simon , Girod Marion , MacAleese Luke , Pieterse Cornelius L. , Schlathölter Thomas , Techert Simone , Bari Sadia 
Published: June 2021

AbstractWe investigated the photoionization and fragmentation of isolated metal protoporphyrin IX cations (MPPIX+ with M=Fe, Co, Zn) by means of vacuum‐ultraviolet (VUV) action spectroscopy in the energy range of 8.5–35 eV. Experiments were carried out in the gas phase by interfacing an electrospray ionization tandem mass spectrometer with a synchrotron beamline. The mass spectra and partial ion yields show that photoexcitation of the precursor ions predominantly leads to .CH2COOH radical side‐chain losses of the macrocycle with additional methyl radical (.CH3) side‐chain losses. Ionization, in contrast, leads to the formation of the intact ionized precursor and various doubly charged fragments which are mostly due to side‐chain cleavages. Although statistical fragmentation dominates, we found evidence for non‐statistical processes such as new fragments involving for example single and double H2O losses, indicating that different relaxation mechanisms are at play upon photoionization compared to photoexcitation. The measured ionization energies were 9.6±0.2 eV, 9.4±0.2 eV and 9.6±0.2 eV for FePPIX+, CoPPIX+ and ZnPPIX+, respectively.