bluuebunny/crossref_metadata_2025_split huggingface dataset:
Discussion Addendum For: Protection of Alcohols Using 2‐Benzyloxy‐1‐Methylpyridinium Trifluoromethanesulfonate: Methyl (
R
)‐(‐)‐3‐Benzyloxy‐2‐methyl Propanoate
Authors: Fulo Harvey F. , Albiniak Philip A. , Dudley* Gregory B. 
Published: April 2020

Abstract
Benzyl ethers are important protecting groups in organic synthesis, but traditional installation methods, such as the Williamson ether synthesis or reaction of an alcohol with benzyl trichloroacetimidate, often limit their formation with substrates containing functional groups unable to tolerate strongly basic or acidic conditions, respectively. The reaction of N,N‐dimethylaniline occurred via an N‐methyl to benzyl exchange instead of the expected electrophilic aromatic substitution. This illustrates that amines can also trap the putative phenylcarbenium species released during the thermal activation of 2‐benzyloxy‐1‐methylpyridinium triflate (BnOPT). Benzylation can generally be achieved chemoselectively using BnOPT with triethylamine in the presence of alcohols, amides, and other functional groups. The mild and nearly neutral conditions associated with the use of BnOPT is the main advantage of the benzylation protocol.
Discussion Addendum for: Preparation of Enantioenriched Homoallylic Primary Amines
Authors: Yus* Miguel 
Published: April 2020

Abstract

One of the most efficient methodologies to prepare amines is the addition of organometallic reagents to imines. From a synthetic point of view, the corresponding allylation presents special interest due to the possible transformation of the introduced carbon‐carbon double bond into other functionalities. This addendum discusses the preparation of enantioenriched homoallylic primary amines. The most commonly used method to prepare the starting enantiomerically pure
N‐tert
‐butylsulfinyl imines is the direct reaction of the corresponding carbonyl compounds with enantiomerically pure commercially available
tert
‐butanesulfinamides and titanium tetraethoxide under thermal or microwave activation. The addendum also provides information on the synthetic applications of chiral N‐sulfinyl homoallylic amines.
Discussion Addendum for: Synthesis of Ynamides by Copper‐Mediated Coupling of 1,1‐Dibromo‐1‐Alkenes with Nitrogen Nucleophiles. Preparation of 4‐Methyl‐N‐(2‐Phenylethynyl)‐N‐(Phenylmethyl)Benzenesulfonamide
Authors: Theunissen Cédric , Thilmany Pierre , Lahboubi Mounsef , Blanchard Nicolas , Evano* Gwilherm 
Published: April 2020

AbstractYnamides provide unique opportunities not only for the introduction of nitrogen‐containing motifs into organic molecules but also for the generation of otherwise hardly accessible highly reactive intermediates. This addendum discusses the synthesis of ynamides with copper as the general solution. It provides information on 1,1‐dibromo‐1‐alkenes as practical alkynylating agents. The addendum also discusses the chemistry of ynamides, which is a versatile and useful building blocks in organic synthesis. The development of efficient synthetic procedures for the preparation of ynamides, including those from 1,1‐dibromo‐1‐alkenes, paved the way for their use as building blocks in organic chemistry. Besides the use of strong acids, electrophilic metal complexes have also proven successful to activate ynamides.
Synthesis of 5‐Hydroxy‐4‐Methoxy‐2‐Methylpyrylium Trifluoromethanesulfonate from Kojic Acid
Authors: Agyemang Nana B. , Murelli* Ryan P. 
Published: April 2020

Abstract
Oxidopyrylium ylides are versatile and reactive species that have been used widely in total synthesis, particularly due to their ability to undergo complexity‐forming [5+2] cycloaddition reactions. Group transfer strategies have been generally limited to intramolecular cycloaddition reactions, however, likely due to the short lifetime of the active ylide. However, in 1992 Wender and Mascarenas found that this limitation can be overcome through the use of methyl triflate based pre‐ylide salt. This article describes the procedure for synthesis of 5‐Hydroxy‐4‐methoxy‐2‐methylpyrylium trifluoromethanesulfonate from Kojic acid. It presents some of the important points to be considered, the conditions that need to be maintained, characterization data, and the reagents required, as well as the techniques used and the equipment setup that are vital to carrying out the process. The article also describes the hazards associated with working with chemicals and the ways to deal with these hazards.
Outline and background of “merged temple”: Study on extension and construction surrounding existing Hindu temples in Varanasi Old City, India
Authors: Yanagisawa Kiwamu , Ohara Ryosuke , Yamamoto Shota 
Published: April 2020

AbstractThis paper discusses the outline and the conditions of the phenomenon known as the “merged temple,” a composite building consisting of the extension of a “sub‐building” covering or wrapping an existing Hindu temple, or “main temple.” These are frequently observed in the Old City of Varanasi (Uttar Pradesh, India). Their number and distribution, morphological variations, forming process, and other properties were investigated through a field survey and interviews with their residents. Merged temples of various shapes and degrees are generated through a combination of extrinsic development pressure and intrinsic characteristics of Hindu temples, their continuity, and their immobility, in the urban space which has historically accumulated numerous temples. In its formative process, the “moderate” plasticity of the Hindu temple building works effectively as a medium, and covering the top of the temple with new construction is carefully avoided.
Cocrystal Strategy toward Multifunctional 3D‐Printing Scaffolds Enables NIR‐Activated Photonic Osteosarcoma Hyperthermia and Enhanced Bone Defect Regeneration
Authors: Xiang Huijing , Yang Qianhao , Gao Youshui , Zhu Daoyu , Pan Shanshan , Xu Tianming , Chen Yu 
Published: April 2020

AbstractMalignant bone tumors are one of the major serious diseases in clinic. Inferior reconstruction of new bone and rapid propagation of residual tumor cells are the main challenges to surgical intervention. Herein, a bifunctional DTC@BG scaffold for near‐infrared (NIR)‐activated photonic thermal ablation of osteosarcoma and accelerated bone defect regeneration is engineered by in situ growth of NIR‐absorbing cocrystal (DTC) on the surface of a 3D‐printing bioactive glass (BG) scaffold. The prominent photothermal conversion performance and outstanding bone regeneration capability of DTC@BG scaffolds originate from the precise tailoring of the bandgap between the electron donors and acceptors of DTC and promote new bone growth performance of BG scaffolds. DTC@BG scaffolds not only significantly promote tumor cell ablation in vitro, but also effectively facilitate bone tumor suppression in vivo. In particular, DTC@BG scaffolds exhibit excellent capability in stimulating osteogenic differentiation and angiogenesis, and finally promote newborn bone formation in the bone defects. This research represents the first paradigm for ablating osteosarcoma and facilitating new bone formation through precise modulation of electron donors and acceptors in the cocrystal, which offers a new avenue to construct high‐efficiency therapeutic platforms based on cocrystal strategy for ablation of malignant bone tumor.
Achieving Rich and Active Alkaline Hydrogen Evolution Heterostructures via Interface Engineering on 2D 1T‐MoS2 Quantum Sheets
Authors: Chen Wenshu , Gu Jiajun , Du Yongping , Song Fang , Bu Fanxing , Li Jinghan , Yuan Yang , Luo Ruichun , Liu Qinglei , Zhang Di 
Published: April 2020

AbstractLarge‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active / heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich / sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm−2, respectively, and has a low Tafel slope of 30 mV dec−1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm−2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions.
2D Covalent Organic Frameworks for Biomedical Applications
Authors: Bhunia Sukanya , Deo Kaivalya A. , Gaharwar Akhilesh K. 
Published: April 2020

AbstractCovalent organic frameworks (COFs) are an emerging class of organic crystalline polymers with well‐defined molecular geometry and tunable porosity. COFs are formed via reversible condensation of lightweight molecular building blocks, which dictate its geometry in two or three dimensions. Among COFs, 2D COFs have garnered special attention due to their unique structure composed of two‐dimensionally extended organic sheets stacked in layers generating periodic columnar π‐arrays, functional pore space, and their ease of synthesis. These unique features in combination with their low density, high crystallinity, large surface area, and biodegradability have made them an excellent candidate for a plethora of applications ranging from energy to biomedical sciences. In this article, the evolution of 2D COFs is briefly discussed in terms of different types of chemical linkages, synthetic strategies of bulk and nanoscale 2D COFs, and their tunability from a biomedical perspective. Next, the biomedical applications of 2D COFs specifically for drug delivery, phototherapy, biosensing, bioimaging, biocatalysis, and antibacterial activity are summarized. In addition, current challenges and emerging approaches in designing 2D COFs for advanced biomedical applications are discussed.
Photoelectrochemical Synthesis of Ammonia with Black Phosphorus
Authors: Liu Danni , Wang Jiahong , Bian Shi , Liu Qian , Gao Yuanhong , Wang Xin , Chu Paul K. , Yu Xue‐Feng 
Published: April 2020

AbstractEfficient production of ammonia using environmentally friendly techniques under ambient conditions is crucial to renewable energy storage and industrial applications, and catalysts with new reaction pathways are highly desirable. In this work, black phosphorus (BP) is used as a metal‐free 2D catalyst for the photoelectrochemical (PEC) nitrogen reduction reaction (NRR). The electrode is fabricated by layer‐by‐layer assembly of BP nanosheets on an indium tin oxide substrate. The PEC NRR activity in the N2 saturated aqueous electrolyte without a sacrificial agent is excellent, as exemplified by an ammonia yield rate of 102.4 µg h−1 mgcat.−1 and Faradaic efficiency of 23.3% at −0.4 V, which are the best among nonmetal catalysts for synthesis of ammonia by photocatalysis and electrocatalysis. Furthermore, the BP electrode shows excellent stability after 6 consecutive cycles. The excellent PEC catalytic properties are attributed to the light excitation enhanced electrocatalytic process and that the external bias promoted photocatalytic process improves ammonia production synergistically. The results not only demonstrate the great potential of BP in PEC catalysis, but also identify a promising technique to produce ammonia under ambient conditions using solar energy and electric energy.
A Highly Efficient Metal‐Free Electrocatalyst of F‐Doped Porous Carbon toward N2 Electroreduction
Authors: Liu Yan , Li Qiuyao , Guo Xu , Kong Xiangdong , Ke Jingwen , Chi Mingfang , Li Qunxiang , Geng Zhigang , Zeng Jie 
Published: April 2020

AbstractN2 electroreduction into NH3 represents an attractive prospect for N2 utilization. Nevertheless, this process suffers from low Faraday efficiency (FE) and yield rate for NH3. In this work, a highly efficient metal‐free catalyst is developed by introducing F atoms into a 3D porous carbon framework (F‐doped carbon) toward N2 electroreduction. At −0.2 V versus reversible hydrogen electrode (RHE), the F‐doped carbon achieves the highest FE of 54.8% for NH3, which is 3.0 times as high as that (18.3%) of pristine carbon frameworks. Notably, at −0.3 V versus RHE, the yield rate of F‐doped carbon for NH3 reaches 197.7 µgNH3 mg−1cat. h−1. Such a value is more than one order of magnitude higher than those of other metal‐free electrocatalysts under the near‐ambient conditions for NH3 product to date. Mechanistic studies reveal that the improved performance in N2 electroreduction for F‐doped carbon originates from the enhanced binding strength of N2 and the facilitated dissociation of N2 into *N2H. F bonding to C atom creates a Lewis acid site due to the different electronegativity between the F and C atoms. As such, the repulsive interaction between the Lewis acid site and proton H suppresses the activity of H2 evolution reaction, thus enhancing the selectivity of N2 electroreduction into NH3.
Bark water storage capacity influences epiphytic orchid preference for host trees
Authors: Zarate‐García Angel M. , Noguera‐Savelli Eliana , Andrade‐Canto Silvia B. , Zavaleta‐Mancera Hilda A. , Gauthier Adrien , Alatorre‐Cobos Fulgencio 
Published: April 2020

PremiseOf all orchid species described, 70% live on phorophytes. Trees offer a vital space with characteristics that influence the successful establishment and life cycle of orchids. Field inventory and distribution analysis suggest that phorophyte selection is biased to certain tree species that would serve as better hosts. Phorophyte bark is known as an important factor that influences this preference, but the chemical and physical properties of bark that contribute to creating a favorable space for orchids are still poorly understood. In this work, the effect of bark physical characteristics on phorophyte preference of tropical orchids was studied.MethodsOrchids and their phorophytes were counted and identified along transects inside two natural reserves in Southeast Mexico. A rhytidome classification was used to describe the bark decoration patterns of the phorophytes. To quantify bark fissuring, we developed a new protocol based on image processing of light micrographs using free‐access software. Bark topology characterization was complemented with scanning electronic microscopy. Maximum and minimum water content was also determined.ResultsAnalyses of bark decorations and bark fissuring were not enough to explain the preference found for some tropical trees. In contrast, a positive relationship was found among water‐storage capacity, bark porosity, and phorophyte preference. The host trees preferred by most orchids have bark with higher pore density and higher water retention after draining.ConclusionsUnexpectedly, the phorophytes preferred by orchids are not those with more fissured bark but those with a higher ability to retain minimum water content after draining, which is a bark property positively correlated with higher pore density. Our data indicate that the bark microenvironment, determined by topology and water storage capacity, has a pivotal role in phorophyte specificity, a key factor that affects orchid diversity and distribution in the world.
Giant Enhancement and Sign Inversion of Optical Kerr Nonlinearity in Random High Index Nanocomposites near Mie Resonances
Authors: Panov Andrey V. 
Published: April 2020

AbstractHigh‐index dielectric nanoantennas excited at Mie‐type resonances have exhibited enormous enhancement of optical nonlinearity. Such nanostructures have been actively studied by researchers in recent years. Here, a numerical analysis study of the optical Kerr effect of nanocomposites consisting of high refractive index (GaP) spheres at the wavelength of 532 nm is presented. This is done by means of 3D finite‐difference time‐domain simulations. The effective nonlinear refractive index of 0.8 µm thick nanocomposites and metasurfaces is evaluated. It is shown that the optical Kerr nonlinearity of the nanocomposites rises by orders in proximity to Mie resonances and may exceed the second‐order refractive index of the bulk material. It is revealed that the sign of the effective optical Kerr coefficient is inverted near the Mie resonances. This effect may be of interest in developing nonlinear optical metadevices.
Non‐Equilibrium Polymerization of Cross‐β Amyloid Peptides for Temporal Control of Electronic Properties
Authors: Bal Subhajit , Ghosh Chandranath , Ghosh Tapan , Vijayaraghavan Ratheesh K. , Das Dibyendu 
Published: April 2020

AbstractHydrophobic collapse plays crucial roles in protein functions, from accessing the complex three‐dimensional structures of native enzymes to the dynamic polymerization of non‐equilibrium microtubules. However, hydrophobic collapse can also lead to the thermodynamically downhill aggregation of aberrant proteins, which has interestingly led to the development of a unique class of soft nanomaterials. There remain critical gaps in the understanding of the mechanisms of how hydrophobic collapse can regulate such aggregation. Demonstrated herein is a methodology for non‐equilibrium amyloid polymerization through mutations of the core sequence of Aβ peptides by a thermodynamically activated moiety. An out of equilibrium state is realized because of the negative feedback from the transiently formed cross‐β amyloid networks. Such non‐equilibrium amyloid nanostructures were utilized to access temporal control over its electronic properties.
Dinuclear Gold(I) Complexes Bearing N,N′‐Allyl‐Bridged Bisimidazolylidene Ligands
Authors: Jakob Christian H. G. , Dominelli Bruno , Rieb Julia , Jandl Christian , Pöthig Alexander , Reich Robert M. , Correia João D. G. , Kühn Fritz E. 
Published: April 2020

AbstractA novel N,N’‐allyl‐bridged bisimidazolium salt and a novel dinuclear Ag(I) and a Au(I) NHC complex are reported. Both metallacyclic complexes have a twisted structural shape due to the rigid allylic system and form two different isomers relating to the position of the double bonds. The allyl‐group shows photoisomerisation, but no reactivity towards bases for the additional coordination of Pd(II).
Mechanistic Insights into the Role of Covalent Triazine Frameworks as Cathodes in Lithium‐Sulfur Batteries
Authors: Troschke Erik , Kensy Christian , Haase Frederik , Dörfler Susanne , Joseph Yvonne , Lotsch Bettina V. , Kaskel Stefan 
Published: April 2020

AbstractThis study illuminates the applicability of covalent triazine frameworks (CTFs) as a potential cathode material in lithium‐sulfur (Li−S) batteries. A systematic synthesis protocol is applied to generate a set of model CTFs containing covalently bound sulfur with varying porosities and conductivities. An in‐depth structural characterization reconsiders the bonding motif of sulfur within the pore system. The model materials are electrochemically evaluated in coin cells. The CTF cathodes exhibit practically no cycling performance as a result of active material loss in carbonate‐based electrolyte (≥200 mAh gsulfur−1 after 200 cycles). Moreover, in ether‐based electrolytes the differentiation between sulfur transformation on the surface of the conductive additive and the (semi‐)conducting CTF matrix is hardly feasible. Based on these results, the influence of the CTF material and the conductive additive with respect to sulfur utilization are discussed, demonstrating the critical role of this class of materials for application in Li−S batteries.
Membrane‐Associated Nucleobase‐Functionalized β‐Peptides (β‐PNAs) Affecting Membrane Support and Lipid Composition
Authors: Höger Geralin A. , Wiegand Markus , Worbs Brigitte , Diederichsen Ulf 
Published: April 2020

AbstractProtein‐membrane interactions are essential to maintain membrane integrity and control membrane morphology and composition. Cytoskeletal proteins in particular are known to interact to a high degree with lipid bilayers and to line the cytoplasmic side of the plasma membrane with an extensive network structure. In order to gain a better mechanistical understanding of the protein–membrane interplay and possible membrane signaling, we started to develop a model system based on β‐peptide nucleic acids (β‐PNAs). These β‐peptides are known to form stable hydrogen‐bonded aggregates due to their helical secondary structure, which serve to pre‐organize the attached nucleobases. After optimization of the β‐PNA solid‐phase peptide synthesis and validation of helix formation, the ability of the novel β‐PNAs to dimerize and interact with lipid bilayers was investigated by both fluorescence and circular dichroism spectroscopy. It was shown that duplex formation occurs rapidly and with high specificity and could also be detected on the surfaces of the lipid bilayers. Hereby, the potential of a β‐PNA‐based peptide system to mimic membrane‐associated protein networks could be demonstrated.
Stress cardiomyopathy should be considered with unexpected hypotension in pregnant women
Authors: Li Chen , Wang Hui , Wu Yina , Duan Jun 
Published: April 2020

AbstractStress‐induced cardiomyopathy is expected that with the wide application of critical ultrasound, ICU doctors will find more cases, particularly among pregnant patients. Patients can actually survive the acute period of excessive stress, and their cardiac function can recover as long as effective treatment measures are taken.
Co@CoAl‐Layered Double Hydroxide/Nitrogen‐Doped Graphene Composite Catalyst for Al−H2O‐Based Batteries: Simultaneous Hydrogen Production and Electricity Generation
Authors: Nadeema Ayasha , Pandurang Kharabe Geeta , Prakash Biswal Dibya , Kurungot Sreekumar 
Published: April 2020

AbstractCurrently, the low energy efficiency of water electrolysis has compelled research toward the development of novel and energy‐effective strategies for low‐cost H2 generation. In this context, we report a new concept of simultaneous H2 and electricity generation by separating out the exothermic self‐sustained Al−H2O reaction via electrochemistry. In addition, to catalyze the cathodic water reduction reaction, a single‐pot and environmentally benign synthesis method is adopted. It results in the design of an electrocatalyst composed of Co@CoAl‐layered double hydroxide core‐shell nanospheres anchored over in situ generated N‐doped graphene. Toward the water reduction reaction, the designed catalyst shows a negative voltage shift of mere around 113 mV with respect to the commercial Pt/C catalyst to reach the benchmark 10 mA cm−2, with excellent stability of approximately 86 % voltage retention after 12 h of continuous operation. The catalytic superiority of our material is evident when taken for battery‐level testing; the fabricated device was able to deliver an average output voltage of around 0.95 V at a discharge current density of 5 mA cm−2 along with H2 liberation, which was also detected and quantified through gas chromatography.