bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the optimal sampling density to characterize spatial heterogeneity of soil carbon stocks in a Karst Region
Authors: Zhang zhenming , Zhou Yunchao , Huang Xianfei
Published: September 2020

The aim of this study is to investigate the spatial distribution of soil organic C stock and to determine the optimal number of samples required for its determination, in a small karst basin. By taking the soil organic C stock in the Houzhai River Basin, calculated on the basis of a 150 by 150 m grid sampling design as original data and selecting sample sets at five grid scales (300, 450, 600, 750, and 900 m), the optimal number of samples for different sampling distances was obtained, using geographic information system (GIS) technology and geostatistical analyses. With increasing sampling distance, the coefficient of variation of the soil organic C stocks first increased and then decreased; the spatial predictions of the soil organic C stock tended to be smoother, and the ability to represent detail was weaker. The prediction accuracy was comprehensively discussed. When the surface soil organic C stock (0–20 cm) was considered, 357 sampling points at a sampling distance of 450 by 450 m could accurately represent its spatial variability. For a depth of 0–100 cm, 200 sampling points and a sampling distance of 600 m could accurately represent the spatial variability in the soil organic C stock. The results of this study could provide data for future studies for the estimation of soil organic C stock in the karst areas of Southwest China and similar areas.
Diamine versus amines blend for CO2 chemical absorption
Authors: Gómez‐Díaz Diego , Muñiz‐Mouro Abel , Navaza José M. , Rumbo Antonio
Published: September 2020

Present work analyses the behavior of aqueous solutions of N,N‐dimethylethylenediamine as chemical solvent for carbon dioxide separation by gas–liquid absorption. The interest of this molecule is centered on the presence of different types of amino centers that confer it the capability to act as a solvent based on amines blend. For this reason, a comparison between diamine and amines blend solvent has been carried out in order to understand the differences between these solvents using absorption and nuclear magnetic resonance studies. This experimental work analyses the influence of amine type, concentration, and ratio between different amines. Also, the effect of gas flow rate used in the bubble column reactor upon the absorption kinetics has been analyzed.
Niche similarity in diploid‐autotetraploid contact zones ofArabidopsis arenosaacross spatial scales
Authors: Morgan Emma J. , Čertner Martin , Lučanová Magdalena , Kubíková Kateřina , Marhold Karol , Kolář Filip
Published: September 2020

Premise

Whole genome duplication is a major evolutionary event, but its role in ecological divergence remains equivocal. When populations of different ploidy (cytotypes) overlap in space, “contact zones” are formed, allowing the study of evolutionary mechanisms contributing toward ploidy divergence. Multiple contact zones per species’ range are often described but rarely leveraged as natural replicates. We explored whether the strength of niche differentiation of diploid and autotetraploidArabidopsis arenosavaries over distinct contact zones and if the frequency of triploids decreases from seedling to adult stage.

Methods

We characterized ploidy composition and habitat preferences in 264 populations across three contact zones using climatic niche modeling. Ecological differences of cytotypes were also assessed using local vegetation surveys at 110 populations within two contact zones, and at the finer scale within five mixed‐ploidy sites. This was complemented by flow cytometry of seedlings.

Results

We found no niche differences between diploid and tetraploid populations within contact zones for either climatic or local environmental variables. Comparisons of cytotypes within mixed‐ploidy sites found weak niche differences that were inconsistent in direction. Triploid individuals were virtually absent (0.14%) in the field, and they were at a similarly low frequency (0.2%) in ex situ germinated seedlings.

Conclusions

This study demonstrates the strength in investigating different spatial scales across several contact zones when addressing ecological niche differentiation between ploidies. The lack of consistent habitat differentiation of ploidies across the scales and locations supports the recently emerging picture that processes other than ecological differentiation may underlie ploidy coexistence in diploid‐autopolyploid systems.
Relationships between mental health and diet during pregnancy and birth outcomes in a lower‐middle income country: “Healthy mothers, healthy communities” study in Vanuatu
Authors: Therrien Ann‐Sophie , Buffa Giovanna , Roome Amanda B. , Standard Elizabeth , Pomer Alysa , Obed Jimmy , Taleo George , Tarivonda Len , Chan Chim W. , Kaneko Akira , Olszowy Kathryn M. , Dancause Kelsey N.
Published: September 2020

Poor maternal mental health during pregnancy is associated with adverse birth outcomes, including lower birthweight and gestational age. However, few studies assess both mental health and diet, which might have interactive effects. Furthermore, most studies are in high‐income countries, though patterns might differ in low‐ and middle‐income countries (LMICs).

Objectives

To analyze relationships between mental health and diet during pregnancy with birth outcomes in Vanuatu, a lower‐middle income country.

Methods

We assessed negative emotional symptoms of depression, anxiety, and stress (referred to as “distress”) and dietary diversity during pregnancy, and infant weight and gestational age at birth, among 187 women. We used multivariate linear regression to analyze independent and interactive relationships between distress, dietary diversity, and birth outcomes, controlling for sociodemographic and maternal health covariates.

Results

There were no direct linear relationships between dietary diversity or distress with infant birthweight or gestational age, and no curvilinear relationships between distress and infant outcomes. We observed interactive relationships between distress and dietary diversity on birthweight, explaining 2.1% of unique variance (P = .024). High levels of distress predicted lower birthweights among women with low dietary diversity. These relationships were not evident among women with moderate or high dietary diversity.

Conclusions

Relationships between mental health and diet might underlie inconsistencies in past studies of prenatal mental health and birthweight. Results highlight the importance of maternal mental health on birthweight in LMICs. Interactive relationships between mental health and diet might ultimately point to new intervention pathways to address the persistent problem of low birthweight in LMICs.
Palladium‐Catalyzed Direct C−H Arylation of Arenes Promoted by Quaternary Ammonium Salt
Authors: Yang Sabyuk , Hong Soon Hyeok
Published: September 2020

A new Pd‐based catalytic system for the direct C−H arylation of arenes was developed. The use of a substoichiometric amount of quaternary ammonium salt as an additive with a Pd source achieved the direct arylation of unactivated arenes under milder reaction conditions in moderate to high yields. The ammonium salt generates the anionic palladium complex, thereby facilitating arylation by a concerted metalation‐deprotonation process.
Sequential One‐Pot Coupling Reactions of Diiodobenzenes, Propiolic Acid, and Aryl Halides for the Synthesis of Diarylalkynyl Arenes
Authors: Ryu Beomseok , Oh Jonghoon , Lee Sunwoo
Published: September 2020

Diiodobenzenes were employed in palladium‐catalyzed one‐pot sequential reactions with propiolic acid and aryl halides to provide the corresponding diarylalkynyl benzenes. The combination of Pd(PPh3)4 (10 mol %) and DBU (5.0 equiv) gave optimal results in the sequence. Reactions with 1,2‐diiodobenzene gave higher yields than those utilizing 1,3‐ and 1,4‐diiodobenzenes. Furthermore, benzenes bearing electron‐donating substituents gave higher yields than those with electron‐withdrawing substituents.
Amidation Reaction of Quinoline‐3‐carboxylic Acids with Tetraalkylthiuram Disulfides under Simple Conditions: A facile Synthesis of Quinoline‐3‐carboxamides
Authors: Hu Jingyan , Ye Xiefeng , Hao Shuai , Zhao Qianrui , Zhao Mingqin , Wei Yuewei , Wu Zhiyong , Wang Na , Ji Xiaoming
Published: September 2020

A highly efficient and simple procedure for the synthesis quinoline‐3‐carboxamides and their analogues via amidation reaction of quinoline‐3‐carboxylic acids with tetraalkylthiuram disulfides has been developed. The reaction proceeds efficiently under simple reaction conditions and features the generality of broad scope of substrates with good yields. This protocol provides a convenient procedure for the synthesis of various aza‐heteroaromatic carboxamides, which is of pharmaceutical interest.
Carbene‐Catalyzed Enantioselective Aldol Reaction: Post‐Aldol Stereochemistry Control and Formation of Quaternary Stereogenic Centers
Authors: Yang Xing , Majhi Pankaj Kumar , Chai Huifang , Liu Bin , Sun Jun , Liu Ting , Liu Yonggui , Zhou Liejin , Xu Jun , Liu Jiawei , Wang Dongdong , Zhao Yanli , Jin Zhichao , Chi Yonggui Robin
Published: September 2020

The dominated approaches for asymmetric aldol reactions have primarily focused on the aldol carbon–carbon bond‐forming events. Here we postulate and develop a new catalytic strategy that seeks to modulate the reaction thermodynamics and control the product enantioselectivities via post‐aldol processes. Specifically, an NHC catalyst is used to activate a masked enolate substrate (vinyl carbonate) to promote the aldol reaction in a non‐enantioselective manner. This reversible aldol event is subsequently followed by an enantioselective acylative kinetic resolution that is mediated by the same (chiral) NHC catalyst without introducing any additional substance. This post‐aldol process takes care of the enantioselectivity issues and drives the otherwise reversible aldol reaction toward a complete conversion. The acylated aldol products bearing quaternary/tetrasubstituted carbon stereogenic centers are formed in good yields and high optical purities.
CeIV‐ and HClO4‐Promoted Assembly of an Fe2IV(μ‐O)2 Diamond Core from its Monomeric FeIV=O Precursor at Room Temperature
Authors: Draksharapu Apparao , Xu Shuangning , Que Lawrence
Published: September 2020

Diiron(IV)‐oxo species are proposed to effect the cleavage of strong C−H bonds by nonheme diiron enzymes such as soluble methane monooxygenase (sMMO) and fatty acid desaturases. However, synthetic mimics of such diiron(IV) oxidants are rare. Herein we report the reaction of (TPA*)FeII (1) (TPA*=tris(3,5‐dimethyl‐4‐methoxypyridyl‐2‐methyl)amine) in CH3CN with 4 equiv CAN and 200 equiv HClO4 at 20 °C to form a complex with an [FeIV2(μ‐O)2]4+ core. CAN and HClO4 play essential roles in this unprecedented transformation, in which the comproportionation of FeIII‐O‐CeIV and FeIV=O/Ce4+ species is proposed to be involved in the assembly of the [FeIV2(μ‐O)2]4+ core.
Highly Selective CO2 Electroreduction to CH4 by In Situ Generated Cu2O Single‐Type Sites on a Conductive MOF: Stabilizing Key Intermediates with Hydrogen Bonding
Authors: Yi Jun‐Dong , Xie Ruikuan , Xie Zai‐Lai , Chai Guo‐Liang , Liu Tian‐Fu , Chen Rui‐Ping , Huang Yuan‐Biao , Cao Rong
Published: September 2020

It is still a great challenge to achieve high selectivity of CH4 in CO2 electroreduction reactions (CO2RR) because of the similar reduction potentials of possible products and the sluggish kinetics for CO2 activation. Stabilizing key reaction intermediates by single type of active sites supported on porous conductive material is crucial to achieve high selectivity for single product such as CH4. Here, Cu2O(111) quantum dots with an average size of 3.5 nm are in situ synthesized on a porous conductive copper‐based metal–organic framework (CuHHTP), exhibiting high selectivity of 73 % towards CH4 with partial current density of 10.8 mA cm−2 at −1.4 V vs. RHE (reversible hydrogen electrode) in CO2RR. Operando infrared spectroscopy and DFT calculations reveal that the key intermediates (such as *CH2O and *OCH3) involved in the pathway of CH4 formation are stabilized by the single active Cu2O(111) and hydrogen bonding, thus generating CH4 instead of CO.
Radical Addition Enables 1,2‐Aryl Migration from a Vinyl‐Substituted All‐Carbon Quaternary Center
Authors: Li Zexian , Wang Minyan , Shi Zhuangzhi
Published: September 2020

An efficient method for photocatalytic perfluoroalkylation of vinyl‐substituted all‐carbon quaternary centers involving 1,2‐aryl migration has been developed. The rearrangement reactions use fac‐Ir(ppy)3, visible light and commercially available fluoroalkyl halides and can generate valuable multisubstituted perfluoroalkylated compounds in a single step that would be challenging to prepare by other methods. Mechanistically, the photoinduced alkyl radical addition to an alkene leads to the migration of a vicinal aryl substituent from its adjacent all‐carbon quaternary center with the concomitant generation of a C‐radical bearing two electron‐withdrawing groups that is further reduced by a hydrogen donor to complete the domino sequence.
A Room‐Temperature Stable Distonic Radical Cation
Authors: Chen Xiaodan , Liu Liu Leo , Liu Shihua , Grützmacher Hansjörg , Li Zhongshu
Published: September 2020

Distonic radical cations (DRCs) with spatially separated charge and radical sites have, so far, largely been observed by gas‐phase mass spectrometry and/or matrix isolation spectroscopy work. Herein, we disclose the isolation of a crystalline dicarbondiphosphide‐based β‐distonic radical cation salt 3.+(BARF) (BARF=[B(3,5‐(CF3)2C6H3)4)]−) stable at room temperature and formed by a one‐electron‐oxidation‐induced intramolecular skeletal rearrangement reaction. Such a species has been validated by electron paramagnetic resonance (EPR) spectroscopy, single‐crystal X‐ray diffraction, UV/Vis spectroscopy and density functional theory (DFT) calculations. Compound 3.+(BARF) exhibits a large majority of spin density at a two‐coordinate phosphorus atom (0.74 a.u.) and a cationic charge located predominantly at the four‐coordinate phosphorus atom (1.53 a.u.), which are separated by one carbon atom. This species represents an isolable entity of a phosphorus radical cation that is the closest to a genuine phosphorus DRC to date.
The Key Role of the Interface in the Highly Sensitive Mechanochromic Luminescence Properties of Hybrid Perovskites
Authors: Ben Haj Salah Maroua , Mercier Nicolas , Dittmer Jens , Zouari Nabil , Botta Chiara
Published: September 2020

Hybrid perovskite (HP) materials are of interest in photovoltaics and lighting applications. Here we report that hybrid perovskite composites, as crystallized powders, can behave as intelligent materials showing highly sensitive and reversible mechanochromic luminescence (MCL). Composites consisting of monolayered 2D HP and 3D HP components exhibit reversible tunable color emission upon mechanical strain. The bluish‐whitish emission of the 2D HP turns into orange in the composite owing to an energy transfer process. The bright green emission, observed as soon as the composite is slightly crushed, originates from the 3D HP after efficient energy funneling from the multi‐layered 2D HP produced at the 2D/3D interface by the mechanical treatment. Besides highlighting the key role of the interfaces in light emission of HP, our findings pave the way for hybrid perovskites as highly sensitive MCL smart materials for mechanosensors, security papers, or optical storage applications.
MeSi(CH2SnRO)3 (R=Ph, Me3SiCH2): Building Blocks for Triangular‐Shaped Diorganotin Oxide Macrocycles
Authors: Ayari Jihed , Göb Christian R. , Oppel Iris M. , Lutter Michael , Hiller Wolf , Jurkschat Klaus
Published: September 2020

The syntheses of the novel silicon‐bridged tris(tetraorganotin) compounds MeSi(CH2SnPh2R)3 (2, R=Ph; 5, R=Me3SiCH2) and their halogen‐substituted derivatives MeSi(CH2SnPh(3−n)In)3 (3, n=1; 4, n=2) and MeSi(CH2SnI2R)3 (6, R=Me3SiCH2) are reported. The reaction of compound 4 with di‐t‐butyltin oxide (t‐Bu2SnO)3 gives the oktokaideka‐nuclear (18‐nuclear) molecular diorganotin oxide [MeSi(CH2SnPhO)3]6 (7) while the reaction of 6 with sodium hydroxide, NaOH, provides the trikonta‐nuclear (30‐nuclear) molecular diorganotin oxide [MeSi(CH2SnRO)3]10 (8, R=Me3SiCH2). Both 7 and 8 show belt‐like ladder‐type macrocyclic structures and are by far the biggest molecular diorganotin oxides reported to date. The compounds have been characterized by elemental analyses, electrospray mass spectrometry (ESI‐MS), NMR spectroscopy, 1H DOSY NMR spectroscopy (7), IR spectroscopy (7, 8), and single‐crystal X‐ray diffraction analysis (2, 7, 8).
Study of mechanical and dynamic mechanical behavior of halloysite nanotube‐reinforced multiscale syntactic foam
Authors: Bakshi Mohammed Sohail , Kattimani Subhaschandra
Published: September 2020

The present study deals with the development of novel cenosphere‐epoxy multiscale syntactic foam (MSF) reinforced with halloysite nanotubes (HNTs). Cenospheres with different volume fractions (0, 20, 30, 40, 50 vol%) and HNTs (1 vol%) used in the fabrication of syntactic foams. The addition of HNTs increases the tensile modulus (42%) and flexural modulus (66%) compared with plain syntactic foam (PSF). Furthermore, FTIR studies reveal the strong hydrogen bonding interaction between HNTs and epoxy. Field emission scanning electron microscopy (FESEM) confirms the unique crack deflection phenomenon by HNT, which indicates the structure–property correlation. In addition, the storage and loss modulus of MSFs is 36 and 113%, respectively (at 30°C) higher than the neat epoxy. Improvement in the tensile and flexural properties along with excellent thermal stability at elevated temperature makes MSF a promising material for structural, weight‐sensitive, and high‐temperature applications.
Observation of latent ion tracks in semicrystalline polymers by scanning electron microscopy
Authors: Blonskaya Irina V. , Kristavchuk Olga V. , Nechaev Alexandr N. , Orelovich Oleg L. , Polezhaeva Olga A. , Apel Pavel Y.
Published: September 2020

Advances in nanotechnology and materials science require further improvement of metrology of nanostructured polymers, in particular, polymers modified by high energy ion beams. The observation of latent ion tracks using various microscopy methods is an important part of studies on heavy ion effects in solids. However, scanning electron microscopy (SEM) has not been utilized for polymers. In the present study, it is shown how SEM can be used to observe latent tracks in semicrystalline polymers. The procedure includes the embrittlement of a polymer specimen by controlled photooxidation and its subsequent fracture. Latent tracks are clearly visible on fractured surfaces as structureless stripes surrounded by an inhomogeneous semicrystalline matrix. Using this method, the latent tracks of Kr, Xe, Au, and Bi ions with energies of 1–11 MeV/u in polyethylene terephthalate and polypropylene films are observed and their diameters are estimated. In contrast to transmission electron microscopy, the suggested novel technique detects the outer track shell consisting of an amorphized polymer. Therefore, SEM observations can complement other commonly used techniques to comprehensively characterize the structure of ion tracks in polymers.
The determinants of social promotion success: A case study of crowdfunding projects
Authors: Wang Feifei , Yang Yang , Tso Geoffrey K. F. , Li Yang
Published: September 2020

Crowdfunding has emerged as a major way to raise financial supports through collaborative contributions of the general public. In recent studies, promotional activities are found to be highly influential to the final outcome of crowdfunding projects. In order to conduct effective and efficient promotional campaigns, it is essential to contiguously monitor their progress status and investigate the determinants to their success during the whole fundraising process. It can help project starters and fundraisers to make decisions on whether and how to adjust the promotional campaigns to make them more useful. To this end, we propose a prediction framework for social influence, an evaluation for success of social promotions, and utilize knowledge gained from both crowdfunding websites and social networks to facilitate the promotional activities. Under two influence definitions based on reshare count and followers count, we find that knowledge gained from aggregate data rather than incremental data is better indicators of the social influence growth. We also discover that some features, including “value of pledged funds” and “number of total promoters,” are of great importance to social influence within the fundraising durations. All these findings could help project starters and fundraisers to make decisions on devising effective social promotions.
Multimodal Imaging and Soft X‐Ray Tomography of Fluorescent Nanodiamonds in Cancer Cells
Authors: Reineck Philipp , Abraham Amanda N. , Poddar Arpita , Shukla Ravi , Abe Hiroshi , Ohshima Takeshi , Gibson Brant C. , Dekiwadia Chaitali , Conesa José J. , Pereiro Eva , Gelmi Amy , Bryant Gary
Published: September 2020

Multimodal imaging promises to revolutionize the understanding of biological processes across scales in space and time by combining the strengths of multiple imaging techniques. Fluorescent nanodiamonds (FNDs) are biocompatible, chemically inert, provide high contrast in light‐ and electron‐based microscopy, and are versatile optical quantum sensors. Here it is demonstrated that FNDs also provide high absorption contrast in nanoscale 3D soft X‐ray tomograms with a resolution of 28 nm in all dimensions. Confocal fluorescence, atomic force, and scanning electron microscopy images of FNDs inside and on the surface of PC3 cancer cells with sub‐micrometer precision are correlated. FNDs are found inside ≈1 µm sized vesicles present in the cytoplasm, providing direct evidence of the active uptake of bare FNDs by cancer cells. Imaging artefacts are quantified and separated from changes in cell morphology caused by sample preparation. These results demonstrate the utility of FNDs in multimodal imaging, contribute to the understanding of the fate of FNDs in cells, and open up new possibilities for biological imaging and sensing across the nano‐ and microscale.
Modeling tangential flow filtration using reverse asymmetric membranes for bioreactor harvesting
Authors: Zhang Da , Patel Parag , Strauss Daniel , Qian Xianghong , Ranil Wickramasinghe S.
Published: September 2020

Tangential flow filtration (TFF) has many advantages for bioreactor harvesting, as the permeate could be introduced directly to the subsequent capture step. However, membrane fouling has limited its widespread use. This is particularly problematic given the high cell densities encountered today. Here, a reverse asymmetric membrane, where the more open surface faces the feed stream and the tighter barrier layer faces the permeate stream, has been investigated. The open surface contains pores up to 40 μm in diameter while the tighter barrier layer has an average pore size of 0.4 μm. Filtration of yeast suspensions has been conducted under a range of conditions. The yeast cells are trapped in the open pore structure. The membrane stabilizes an internal porous cake that acts like a depth filter. This stabilized cake layer can remove particulate matter that would foul the barrier layer if it faced the feed stream. As filtration continues, a surface cake layer forms on the membrane surface. A resistance in series model has been developed to describe the permeate flux during TFF. The model contains three fitted parameters which can easily be determined from constant pressure normal flow filtration experiments and total recycle constant flux TFF experiments. The model can be used to estimate the capacity of the filter for a given feed stream. Our results suggest that using a reverse asymmetric membrane could avoid severe flux decline associated with fouling of the barrier layer during bioreactor harvesting.
HAO‐CNN: Filament‐aware hair reconstruction based on volumetric vector fields
Authors: Ye Zehao , Li Guiqing , Yao Biyuan , Xian Chuhua
Published: September 2020

Hair modeling plays an important role in computer animation, virtual reality, and other applications. This paper proposes an encoder‐decoder network, named HAO‐CNN, to recover 3D hair strand models from a single image. Specifically, HAO‐CNN generates a volumetric vector field (VVF) from the oriented map of hairstyles. However, instead of directly working on the full resolution VVFs, we introduce the adapted O‐CNN to predict the adaptive representation of VVFs in order to greatly reduce the memory cost. In addition, we fuse the features from different layers of the encoding stage for both capturing the global structure and being aware of hair filaments. Considering the difficulty of acquiring true three‐dimensional (3D) hair models, we augment the dataset with 340 3D hair models by 1,800 hair models via interactive editing using the software and render their oriented maps as training data. Then given a hair photo associated with human head, we segment out the hair region, compute its two‐dimensional oriented map using Gabor filter, and feed it into the network to produce a hair volumetric vector field which is then converted into hairline models using an improved VVF‐to‐strands algorithm. This greatly decreases the time cost of approaches based on volumetric vector fields.
OCRE Domains of Splicing Factors RBM5 and RBM10: Tyrosine Ring‐Flip Frequencies Determined by Integrated Use of 1H NMR Spectroscopy and Molecular Dynamics Simulations
Authors: Martin Bryan T. , Malmstrom Robert D. , Amaro Rommie E. , Wüthrich Kurt
Published: September 2020

The 55‐residue OCRE domains of the splicing factors RBM5 and RBM10 contain 15 tyrosines in compact, globular folds. At 25 °C, all 15 tyrosines show symmetric 1H NMR spectra, with averaged signals for the pairs of δ‐ and ϵ‐ring hydrogens. At 4 °C, two tyrosines were identified as showing 1H NMR line‐broadening due to lowered frequency of the ring‐flipping. For the other 13 tyrosine rings, it was not evident, from the 1H NMR data alone, whether they were either all flipping at high frequencies, or whether slowed flipping went undetected due to small chemical‐shift differences between pairs of exchanging ring hydrogen atoms. Here, we integrate 1H NMR spectroscopy and molecular dynamics (MD) simulations to determine the tyrosine ring‐flip frequencies. In the RBM10‐OCRE domain, we found that, for 11 of the 15 tyrosines, these frequencies are in the range 2.0×106 to 1.3×108 s−1, and we established an upper limit of <1.0×106 s−1 for the remaining four residues. The experimental data and the MD simulation are mutually supportive, and their combined use extends the analysis of aromatic ring‐flip events beyond the limitations of routine 1H NMR line‐shape analysis into the nanosecond frequency range.
Surface Ligand Density Switches Glycovesicles between Monomeric and Multimeric Lectin Recognition
Authors: Yadav Shivender , Naresh Kottari , Jayaraman Narayanaswamy
Published: September 2020

Carbohydrate‐protein interactions define a multitude of cellular recognition events. We present herein synthetic glycovesicles as cell‐surface mimics in order to switch the nature of lectin recognition. The covalent glycovesicles, constituted with diacetylene monomers of various ligand densities at their surfaces, are prepared through photo‐polymerization. Vesicles with sparsely imbedded ligands engage in a lectin interaction leading to the formation of a dense, crosslinked multimeric complex. On the other hand, vesicles with many ligands, or completely covered with them, switch the lectin interaction to form a fully soluble monomeric complex, without crosslinking. Nanomolar dissociation constants govern these interactions, as assessed by a ligand‐displacement assay. The study demonstrates the switching nature – between monomeric and multimeric – of the interaction as a function of ligand density in the vesicles; the results are directly relevant to understanding such a phenomenon occurring at cell surfaces.
Molecular Basis of the Antiangiogenic Action of Rosmarinic Acid, a Natural Compound Targeting Fibroblast Growth Factor‐2/FGFR Interactions
Authors: Pagano Katiuscia , Carminati Laura , Tomaselli Simona , Molinari Henriette , Taraboletti Giulia , Ragona Laura
Published: September 2020

Fibroblast growth factor (FGF2)/fibroblast growth factor receptor (FGFR) signalling plays a major role both in physiology and in several pathologies, including cancer development, metastasis formation and resistance to therapy. The development of small molecules, acting extracellularly to target FGF2/FGFR interactions, has the advantage of limiting the adverse effects associated with current intracellular FGFR inhibitors. Herein, we discuss the ability of the natural compound rosmarinic acid (RA) to induce FGF2/FGFR complex dissociation. The molecular‐level description of the FGF2/FGFR/RA system, by NMR spectroscopy and docking, clearly demonstrates that RA binds to the FGFR‐D2 domain and directly competes with FGF2 for the same binding site. Direct and allosteric perturbations combine to destabilise the complex. The proposed molecular mechanism is validated by cellular studies showing that RA inhibits FGF2‐induced endothelial cell proliferation and FGFR activation. Our results can serve as the basis for the development of new extracellular inhibitors of the FGF/FGFR pathways.
A Case of bilateral concomitant inguinal and femoral hernias treated with transabdominal preperitoneal repair
Authors: Uesato Yasunori , Takatsuki Mitsuhisa
Published: September 2020

Synchronous bilateral hernias are very rare, and subclinical hernias as this case are very difficult to diagnose preoperatively. Laparoscopic surgery, which can accurately confirm and reinforce the weakened bilateral inguinal region, was very useful.
Male pseudohermaphroditism: A case study of 46,XY disorder of sexual development using whole‐exome sequencing
Authors: Naumova Oxana Yu. , Rychkov Sergey Yu. , Burenkova Olga V. , Solodunova Maria Yu. , Polyanskaya Irina V. , Arintcina Irina A. , Zhukova Marina A. , Ovchinnikova Irina V. , Zhukova Olga V. , Grigorenko Elena L.
Published: September 2020

The study shows that whole‐exome sequencing is a promising approach to detect novel variants—and gene candidates in DSD, that, as a future direction, may improve the diagnostic gene panels for this heterogeneous disorder.
Photoswitchable phosphines in catalysis
Authors: Medici Fabrizio , Goual Nawel , Delattre Vincent , Voituriez Arnaud , Marinetti Angela
Published: September 2020

Photoswitchable catalysts based on phosphorus ligands have been overlooked so far, despite the growing current interest for catalysts control through external stimuli. This review surveys the current knowledge in the field, including synthetic approaches to photoswitchable phosphines and their transition metal complexes, and applications in rhodium, palladium, gold, ruthenium and copper catalysis. This survey demonstrates that both regulation of the catalytic activity and tuning of the chemo‐ and enantioselectivity can be achieved using irradiation as a non‐invasive external stimulus. Non‐catalytic uses of photoswitchable phosphines in organic synthesis are also mentioned.
Deactivation Mechanism and Enhanced Durability of V2O5/TiO2–SiO2–MoO3 Catalysts for NH3−SCR in the Presence of SO2
Authors: Kuma Ryoji , Kitano Tomoyuki , Tsujiguchi Takuya , Tanaka Tsunehiro
Published: September 2020

V2O5/TiO2‐type catalysts are widely applied for selective catalytic NO reduction by NH3 (NH3‐SCR), but enhanced sulfur tolerance and low‐temperature activity are required. Herein, V2O5/TiO2−SiO2−MoO3 (V/TSM) was demonstrated to have excellent catalytic activity and durability for NH3‐SCR in the presence of SO2 at temperatures lower than 200 °C. The deactivation mechanism and factors influencing SO2 durability were investigated using catalytic durability tests, Fourier‐transform infrared spectroscopy, and temperature‐programmed desorption/decomposition. Our results revealed that (NH4)2S2O3 and NH4HSO4 form on catalyst surfaces by NH3−SO2−H2O reactions at low temperatures, resulting in catalyst deactivation via pore blockage. However, V/TSM was found to possess an increased number of active sites for decomposing deposited ammonium sulfate salts. The decomposition activity was related to the solid acidity, which enhanced SO2 desorption and reactions between ammonium sulfate salts and NO. These findings will contribute to the development of catalysts with improved lifetimes for NH3−SCR.
Role of Recrystallization in Alkaline Treatment on the Catalytic Activity of 1‐Butene Epoxidation
Authors: Zuo Yi , Yang Liqian , Jiang Xiao , Ma Mengtong , Wang Yanli , Liu Min , Song Chunshan , Guo Xinwen
Published: September 2020

Two alkylol amines, which were ethanolamine (EOA) and triethanolamine (TEOA), were used to posttreat nanosized titanium silicalite‐1 (TS‐1) to improve its catalytic activity for 1‐butene epoxidation. Comparative studies were conducted to clarify the influences of the EOA and TEOA concentrations on the physicochemical properties through detailed characterization. EOA treatment can dissolve the framework Si, [SiO4], on the external surface of TS‐1, generating some macropores. TEOA serves as structure‐directing agent to form MFI topology other than the dissolution of [SiO4], and promotes the recrystallization of [SiO4], forming new TS‐1 particles over the external surface. The two treatments can both improve the catalytic activity of 1‐butene epoxidation, but the samples treated with TEOA exhibit better catalytic stability. This can be attributed to the characteristic recrystallization of [SiO4] in the case of TEOA treatment, stabilizing the structure of TS‐1 and maintaining more framework Ti and intercrystal space.
Predictors of Broaching: Multicultural Competence, Racial Color Blindness, and Interpersonal Communication
Authors: King Kelly M. , Summers LaTonya
Published: September 2020

Predictors of broaching race for trainees and professionals (N = 85) seeing clients were examined in a correlational design. Results showed multicultural competence was a strong positive predictor of broaching, color blindness was a moderate negative predictor, and interpersonal communication as a predictor was mediated by multicultural competence. Demographics and experience were also studied to guide recommendations for broaching.
Practical Application of Hierarchical Beta Zeolite in a Vacuum Gas Oil Hydrocracking Catalyst
Authors: Zhang Weimin , Qin Bo , Li Wenxi , Hou Kaige , Du Yanze , Ma Jinghong , Li Ruifeng
Published: September 2020

A hierarchical Beta zeolite has been successfully mass‐prepared hydrothermally and dynamically in a pilot‐scale autoclave by an economical and simple process with low‐cost raw materials. The characterization results indicated that the pilot‐scale hierarchical Beta zeolite has the same textural, structural, and acidic properties like the bench‐scale sample. Moreover, the catalyst composed of the pilot‐scale hierarchical H‐Beta zeolite showed higher activity and selectivity to the middle distillate than that containing microporous Beta zeolite in catalytic hydrocracking of vacuum gas oil (VGO) evaluated by an industrial pilot installation in running of 3000 h, due to the increased accessibility and the reduction of diffusion constraint of large molecules to acid sites in the Beta zeolite framework.
A Dendron‐Based Fluorescence Turn‐On Probe for Tumor Detection
Authors: Liu Changren , Zhang Ling'e , Zhou Sensen , Zhang Xiaoke , Wu Wei , Jiang Xiqun
Published: September 2020

Specifically amplifying the emission signals of optical probes in tumors is an effective way to improve the tumor‐imaging sensitivity and contrast. In this paper, the first case of dendron‐based fluorescence turn‐on probes mediated by a Förster resonance energy transfer (FRET) mechanism is reported. Dendrons up to the fourth generation with a hydrophilic oligo(ethylene glycol) scaffold are synthesized by a solid‐phase synthesis strategy, and show precise and defect‐free chemical structures. To construct the fluorescence turn‐on probe, one Cy5.5 molecule is conjugated to the focal of a G3 dendron through a robust linkage and eight Black Hole Quencher 3 (BHQ‐3) molecules are conjugated to its periphery through a PEG chain bearing a reductively cleavable disulfide linkage. By in vitro and in vivo experiments, it is demonstrated that the fluorescence of the dendron‐based probe can be activated effectively and rapidly in the reductive environments of tumor cells and tissues, and the probe thus exhibits amplified tumor signals and weak normal tissue signals. Compared with the reported nanoscale turn‐on probes, the dendron‐based probe has several significant advantages, such as well‐defined chemical structure, precisely controllable fluorophore/quencher conjugation sites and ratio, desirable chemical stability, and reproducible pharmacokinetic and pharmacological profiles, and is very promising in tumor detection.
A Water‐Soluble Iridium Photocatalyst for Chemical Modification of Dehydroalanines in Peptides and Proteins
Authors: van Lier Roos C. W. , de Bruijn A. Dowine , Roelfes Gerard
Published: September 2020

Dehydroalanine (Dha) residues are attractive noncanonical amino acids that occur naturally in ribosomally synthesised and post‐translationally modified peptides (RiPPs). Dha residues are attractive targets for selective late‐stage modification of these complex biomolecules. In this work, we show the selective photocatalytic modification of dehydroalanine residues in the antimicrobial peptide nisin and in the proteins small ubiquitin‐like modifier (SUMO) and superfolder green fluorescent protein (sfGFP). For this purpose, a new water‐soluble iridium(III) photoredox catalyst was used. The design and synthesis of this new photocatalyst, [Ir(dF(CF3)ppy)2(dNMe3bpy)]Cl3, is presented. In contrast to commonly used iridium photocatalysts, this complex is highly water soluble and allows peptides and proteins to be modified in water and aqueous solvents under physiologically relevant conditions, with short reaction times and with low reagent and catalyst loadings. This work suggests that photoredox catalysis using this newly designed catalyst is a promising strategy to modify dehydroalanine‐containing natural products and thus could have great potential for novel bioconjugation strategies.
DpgC‐Catalyzed Peroxidation of 3,5‐Dihydroxyphenylacetyl‐CoA (DPA‐CoA): Insights into the Spin‐Forbidden Transition and Charge Transfer Mechanisms**
Authors: Ortega Pablo , Zanchet Alexandre , Sanz‐Sanz Cristina , Gómez‐Carrasco Susana , González‐Sánchez Lola , Jambrina Pablo G.
Published: September 2020

Despite being a very strong oxidizing agent, most organic molecules are not oxidized in the presence of O2 at room temperature because O2 is a diradical whereas most organic molecules are closed‐shell. Oxidation then requires a change in the spin state of the system, which is forbidden according to non‐relativistic quantum theory. To overcome this limitation, oxygenases usually rely on metal or redox cofactors to catalyze the incorporation of, at least, one oxygen atom into an organic substrate. However, some oxygenases do not require any cofactor, and the detailed mechanism followed by these enzymes remains elusive. To fill this gap, here the mechanism for the enzymatic cofactor‐independent oxidation of 3,5‐dihydroxyphenylacetyl‐CoA (DPA‐CoA) is studied by combining multireference calculations on a model system with QM/MM calculations. Our results reveal that intersystem crossing takes place without requiring the previous protonation of molecular oxygen. The characterization of the electronic states reveals that electron transfer is concomitant with the triplet–singlet transition. The enzyme plays a passive role in promoting the intersystem crossing, although spontaneous reorganization of the water wire connecting the active site with the bulk presets the substrate for subsequent chemical transformations. The results show that the stabilization of the singlet radical‐pair between dioxygen and enolate is enough to promote spin‐forbidden reaction without the need for neither metal cofactors nor basic residues in the active site.
Quadruplex–Duplex Junction: A High‐Affinity Binding Site for Indoloquinoline Ligands
Authors: Vianney Yoanes Maria , Preckwinkel Pit , Mohr Swantje , Weisz Klaus
Published: September 2020

A parallel quadruplex derived from the Myc promoter sequence was extended by a stem‐loop duplex at either its 5′‐ or 3′‐terminus to mimic a quadruplex–duplex (Q–D) junction as a potential genomic target. High‐resolution structures of the hybrids demonstrate continuous stacking of the duplex on the quadruplex core without significant perturbations. An indoloquinoline ligand carrying an aminoalkyl side chain was shown to bind the Q–D hybrids with a very high affinity in the order Ka≈107 m−1 irrespective of the duplex location at the quadruplex 3′‐ or 5′‐end. NMR chemical shift perturbations identified the tetrad face of the Q–D junction as specific binding site for the ligand. However, calorimetric analyses revealed significant differences in the thermodynamic profiles upon binding to hybrids with either a duplex extension at the quadruplex 3′‐ or 5′‐terminus. A large enthalpic gain and considerable hydrophobic effects are accompanied by the binding of one ligand to the 3′‐Q–D junction, whereas non‐hydrophobic entropic contributions favor binding with formation of a 2:1 ligand‐quadruplex complex in case of the 5′‐Q–D hybrid.
High‐Efficiency FRET Processes in BODIPY‐Functionalized Quantum Dot Architectures
Authors: Panniello Annamaria , Trapani Mariachiara , Cordaro Massimiliano , Dibenedetto Carlo Nazareno , Tommasi Raffaele , Ingrosso Chiara , Fanizza Elisabetta , Grisorio Roberto , Collini Elisabetta , Agostiano Angela , Curri Maria Lucia , Castriciano Maria Angela , Striccoli Marinella
Published: September 2020

Efficient FRET systems are developed combining colloidal CdSe quantum dots (QDs) donors and BODIPY acceptors. To promote effective energy transfer in FRET architectures, the distance between the organic fluorophore and the QDs needs to be optimized by a careful system engineering. In this context, BODIPY dyes bearing amino‐terminated functionalities are used in virtue of the high affinity of amine groups in coordinating the QD surface. A preliminary QD surface treatment with a short amine ligand is performed to favor the interaction with the organic fluorophores in solution. The successful coordination of the dye to the QD surface, accomplishing a short donor–acceptor distance, provides effective energy transfer already in solution, with efficiency of 76 %. The efficiency further increases in the solid state where the QDs and the dye are deposited as single coordinated units from solution, with a distance between the fluorophores down to 2.2 nm, demonstrating the effectiveness of the coupling strategy.
Improvement of Molecular Diagnosis Using Domain‐Level Single‐Nucleotide Variants by Eliminating Unexpected Secondary Structures
Authors: Tan Yun , Zhong Weiye , Tang Weiyang , Fan Jin , Zhang Xiaohui , Guo Donghua , Wu Xiaolong , Liu Yizhen
Published: September 2020

Identification of single‐nucleotide variants (SNVs) is of great significance in molecular diagnosis. The problem that should not be ignored in the identification process is that the unexpected secondary structure of the target nucleic acid may greatly affect the detection accuracy. Herein, we proposed a conditional domain‐level SNV diagnosis strategy, in which the subsequent SNV detection can only be carried out after eliminating the unexpected secondary structure of target DNA. Specifically, the target DNA is assembled into a rigid double strand, which makes folding the target DNA difficult and the unexpected secondary structure is eliminated. Based on this double‐stranded structure, specially designed probes are used to detect double‐stranded properties and report abundant domain‐level oligonucleotide information to improve the effective information in the detection results and complete domain‐level SNV diagnosis. If the unexpected secondary structure is not eliminated, the detector will first detect it and feed back to us, ensuring the accuracy of the subsequent detection results. With the occurrence (or not) of SNV and the change of the SNV site, in the proof‐of‐concept experiment, we successfully identified the four homologous sequences to be tested related to BRAF gene.
Push–Pull Bisnaphthyridylamine Supramolecular Nanoparticles: Polarity‐Induced Aggregation and Crystallization‐Induced Emission Enhancement and Fluorescence Resonance Energy Transfer
Authors: Hagihara Ryusuke , Umeno Tomohiro , Ueki Shoji , Yoshihara Daisuke , Fuchi Yasufumi , Usui Kazuteru , Sakuma Masaomi , Yamada Ken‐ichi , Karasawa Satoru
Published: September 2020

Emissive push–pull‐type bisnaphthyridylamine derivatives (BNA‐X: X=Me, Et, Bzl, Ph, BuBr, and BuTEMPO) aggregate in aqueous methanol. Furthermore, a two‐step emission and aggregation process is controllable by varying the methanol‐to‐water ratio. At 2:3 MeOH/H2O, crystallization‐induced emission enhancement (CIEE) occurs via formation of an emissive crystal phase, whereas, at 1:9 MeOH/H2O, aggregation‐induced emission enhancement (AIEE) occurs, induced by emissive supramolecular nanoparticles (NPs). For BNA‐Ph, the emission quantum yield was 25 times higher in aqueous methanol than that in pure methanol. Despite the high hydrophobicity of BNA‐X (C log P=6.1–8.0), the spherical NPs were monodisperse (polydispersity indices <0.2). Moreover, the emissive NPs exhibited fluorescence resonance energy transfer (FRET) with pyrene; however, for BNA‐X bearing the TEMPO radical (BNA‐BuTEMPO), no FRET was observed because of quenching. In particular, the BNA‐BuTEMPO NPs have a slow rotational correlation time (1.3 ns), suggesting applications as magnetic resonance imaging contrast agents with large relaxivity.
Cucurbit[n]urils for Supramolecular Catalysis
Authors: Tang Bohan , Zhao Jiantao , Xu Jiang‐Fei , Zhang Xi
Published: September 2020

The control over chemical reactivity and selectivity are always pursued. Using non‐covalent interactions to achieve efficient and selective catalysis is an essential goal of supramolecular catalysis. Supramolecular catalysis based on cucurbit[n]urils (CB[n]s) possesses distinct characteristics for the unique structure of CB[n]s. CB[n]s are a family of pumpkin‐shaped host molecules with various molecular sizes, rigid structures, electronegative portals and wealthy host‐guest chemistry. Herein, we summarize the three major mechanisms of CB[n]s based supramolecular catalysis. Owing to the structural properties of CB[n]s, CB[n]s can serve as nanoreactors and steric hindrance to modulate the reactivity of substrates. They can also catalyze the reactions by modulating the reactivity of ionized intermediates. Recent progresses on the CB[n]s based supramolecular catalysis are introduced in this Minireview and the future development in this field is discussed. It is anticipated that this review provides insights into the mechanism of CB[n]s based supramolecular catalysis and may help scientists find new opportunities in this field.
Lignin from Annual Plants as Raw Material Source for Flavors and Basic Chemicals
Authors: Jahn Annika , Hoffmann Anton , Blaesing Luisa , Kunde Fabian , Bertau Martin , Bremer Martina , Fischer Steffen
Published: September 2020

The enzymatic conversion of lignins, possibly in combination with electrochemical oxidation, makes aromatics such as syringol, guaiacol, vanillin and catechol available in the qualities required by the fragrance industry. The lignins were obtained by soda digestion from wheat straw and Miscanthus, characterized and then converted with laccases. The overall yield amounted up to 9 wt % with a product spectrum confined to four substances. Catechol was the major product, with a fraction of ≈75 %. It can easily be isolated by extraction with acetone.