Nickel-catalysed alkylation of C(sp3)–H bonds with alcohols: direct access to functionalised N-heteroaromatics

2018 ◽  
Vol 54 (87) ◽  
pp. 12369-12372 ◽  
Author(s):  
Mari Vellakkaran ◽  
Jagadish Das ◽  
Sourajit Bera ◽  
Debasis Banerjee
Keyword(s):  
Base Metal ◽  
Direct Access ◽  
First Time

Base-metal catalysed C(sp3)–H bond functionalisation of methyl-N-heteroaromatics with alcohols is reported for the first time.

scholarly journals Visualization of the Ludford column

2013 ◽  
Vol 721 ◽  
pp. 438-453 ◽  
Author(s):  
Oleg Andreev ◽  
Yurii Kolesnikov ◽  
André Thess
Keyword(s):  
Liquid Metals ◽  
Basic Feature ◽  
Direct Access ◽  
Experimental Procedure ◽  
Stagnant Region ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Truncated Cylinder ◽  
First Time ◽  
Flow Experiments

AbstractWhen a liquid metal flows around a truncated cylinder in the presence of a magnetic field which is parallel to the axis of the cylinder, a stagnant region develops above the cylinder. We call this region a Ludford column. The Ludford column represents the magnetohydrodynamics (MHD) analogue of the well-known Taylor columns in rotating flows. Whereas Taylor columns can be easily visualized using dye, the visualization of Ludford columns has remained elusive up to now because liquid metals are opaque. We demonstrate that this fundamental limitation of experimental MHD can be overcome by using a superconducting 5 T magnet. This facility permits us to perform MHD experiments in which the opaque liquid metals are replaced with a transparent electrolyte while maintaining the key MHD effects. We report results of a series of flow experiments in which an aqueous solution of sulphuric acid flows around a bar with square cross-section (which for simplicity shall be referred to as a cylinder). We vary the Reynolds number in the range $5\lt Re\lt 100$ and the Hartmann number in the range $0\lt Ha\lt 14$. The experimental procedure involves flow visualizations using tracer particles as well as velocity measurements using particle image velocimetry (PIV). Our experiments provide direct access to the Ludford column for the first time and reveal the spatial structure of this basic feature of MHD flows.

Asymmetric formal synthesis of (+)-cycloclavine

2017 ◽  
Vol 53 (96) ◽  
pp. 12902-12905 ◽  
Author(s):  
Jin-Quan Chen ◽  
Le-Le Song ◽  
Feng-Xing Li ◽  
Zi-Fa Shi ◽  
Xiao-Ping Cao
Keyword(s):  
Asymmetric Synthesis ◽  
Direct Access ◽  
Formal Synthesis ◽  
First Time

The asymmetric synthesis of Szántay's amine (+)-2, the pivotal precursor for direct access to (+)-cycloclavine (1), is described for the first time in eleven steps with 19.7% overall yield from the commercially available 4-bromoindole.

scholarly journals Asymmetric Zinc Catalysis in Green One-Pot Processes

2021 ◽  
Vol 25 ◽  
Author(s):  
Hélène Pellissier
Keyword(s):  
Environmentally Benign ◽  
Direct Access ◽  
Tandem Reactions ◽  
Chiral Molecules ◽  
One Pot ◽  
First Time ◽  
Zinc Catalysis

: This review collects for the first time enantioselective one-pot processes promoted by green chiral zinc catalysts. It illustrates how much these cheap, non-toxic and environmentally benign catalysts allow unprecedented asymmetric domino and tandem reactions of many types to be achieved, allowing a direct access to a wide variety of very complex chiral molecules.

Metal-free oxidative decarbonylative coupling of aromatic aldehydes with arenes: direct access to biaryls

2015 ◽  
Vol 51 (27) ◽  
pp. 5925-5928 ◽  
Author(s):  
Ren-Jin Tang ◽  
Qing He ◽  
Luo Yang
Keyword(s):  
Aromatic Aldehydes ◽  
Direct Access ◽  
Metal Free ◽  
First Time ◽  
Biaryl Compounds

A metal-free oxidative decarbonylative coupling of aromatic aldehydes with electron-rich or electron-deficient arenes to produce biaryl compounds was developed for the first time.

scholarly journals iPod: A personalized sound world for its consumers

Comunicar ◽  
2010 ◽  
Vol 17 (34) ◽  
pp. 55-63 ◽  
Author(s):  
Michael Bull
Keyword(s):  
Cultural Theory ◽  
Specific Form ◽  
Direct Access ◽  
Specific Nature ◽  
Public And Private ◽  
Private Space ◽  
Technological Support ◽  
The World ◽  
Mode Of Being ◽  
First Time

For the first time in industrialised culture, over fifty percent of the population possesses the ability to privatise whatever environment they might be in through the use of a dedicated MP3 player or through a mobile phone with MP3 capabilities. The consumption of technologically mediated sound in the 20th and 21st centuries represents an increasingly significant mode of ‘being-in-theworld’ in which the ‘self’ claims a mobile and auditory territory for itself through a specific form of ‘sensory gating’ permitting the user to screen out unwanted sounds through the creation of their own seductive soundscape. The untrammelled pleasures of creating a privatised mobile soundworld resonates through urban and cultural theory posing a set of interrelated theoretical problems relating to both our relation to the spaces we move through. the nature and meaning of public and private space., the potential for urban aestheticisation, urban retreat and withdrawalIn this paper I discuss the use of Apple iPod in terms of its use as a technological support system of users. The paper draws upon the Internet responses of over one thousand iPod users worldwide between 2004 and 2005. The paper investigates the specific nature of auditory mediation that use entails. It argues that iPod use can usefully be interpreted as a form of pleasurable toxicity within which the ‘total mediated’ world of users lies a dream of unmediated experience - of direct access to the world and one’s emotions. Por primera vez desde el nacimiento de la cultura industrializada, más de la mitad de la población es capaz de personalizar cualquier parte de su entorno gracias a un reproductor de MP3 o a través de un teléfono móvil. El consumo de sonidos mediados tecnológicamente durante los siglos XX y XXI representa una forma cada vez más importante de «estar-en-el-mundo»; el «yo» reclama un territorio sonoro móvil a través de una especie de «compuerta sensorial» que le permite filtrar los sonidos que no le interesan y crear el paisaje sonoro que más le satisface. El placer sin límites que supone crear un mundo sonoro móvil de carácter privado plantea, para la teoría urbana y cultural, un conjunto de problemas teóricos que tienen que ver con la relación con los espacios en los que nos movemos, la naturaleza y el significado del espacio público y privado, el potencial de la estetización de lo urbano, y la incomunicación de la ciudad. También cuestiona el conocimiento de las tecnologías que se usan para mediatizar gran parte de la experiencia cotidiana. En este artículo se analiza el uso del iPod como soporte tecnológico para los consumidores. Se basa en las respuestas de más de un millar de usuarios entre 2004-05. Plantea que el uso del iPod puede ser interpretado positivamente si se considera como una forma de toxicidad placentera en la que bajo el mundo «totalmente mediatizado» de los usuarios subyace un anhelo de experiencia no mediatizada –de acceso directo al mundo y a las emociones de cada uno.

scholarly journals Large evanescently-induced Brillouin scattering at the surrounding of a nanofibre

2021 ◽  
Author(s):  
Fan Yang ◽  
Flavien Gyger ◽  
Adrien Godet ◽  
Jacques Chretien ◽  
Li Zhang ◽  
...  
Keyword(s):  
Free Space ◽  
Brillouin Scattering ◽  
Single Mode ◽  
Gain Coefficient ◽  
Direct Access ◽  
Brillouin Spectroscopy ◽  
Acoustic Interaction ◽  
Photonic Waveguides ◽  
Brillouin Gain ◽  
First Time

Abstract Brillouin scattering has been widely exploited for advanced photonics functionalities such as microwave photonics, signal processing, sensing, lasing, and more recently in micro- and nano-photonic waveguides. So far, all the works have focused on the opto-acoustic interaction driven from the core region of micro- and nano-waveguides. Here we observe, for the first time, an efficient Brillouin scattering generated by an evanescent field nearby a sub-wavelength waveguide embedded in a pressurised gas cell, with a maximum gain coefficient of 18.90 ± 0.17 m^(-1)W^(-1). This gain is 11 times larger than the highest Brillouin gain obtained in a hollow-core fibre and 79 times larger than in a standard single-mode fibre. The realisation of strong free-space Brillouin scattering from a waveguide benefits from the flexibility of confined light while providing a direct access to the opto-acoustic interaction, as required in free-space optoacoustics such as Brillouin spectroscopy and microscopy. Therefore, our work creates an important bridge between Brillouin scattering in waveguides, Brillouin spectroscopy and microscopy, and opens new avenues in light-sound interactions, optomechanics, sensing, lasing and imaging.

scholarly journals Using Satellite Interferometry to Infer Landslide Sliding Surface Depth and Geometry

2020 ◽  
Vol 12 (9) ◽  
pp. 1462
Author(s):  
Emanuele Intrieri ◽  
William Frodella ◽  
Federico Raspini ◽  
Federica Bardi ◽  
Veronica Tofani
Keyword(s):  
Cross Section ◽  
Direct Access ◽  
Sliding Surface ◽  
Movement Kinematics ◽  
Easy Task ◽  
Combined Use ◽  
Different Types ◽  
Geophysical Information ◽  
First Time ◽  
Insight Into

Information regarding the shape and depth of a landslide sliding surface (LSS) is fundamental for the estimation of the volume of the unstable masses, which in turn is of primary importance for the assessment of landslide magnitude and risk scenarios as well as in refining stability analyses. To assess an LSS is not an easy task and is generally time-consuming and expensive. In this work, a method existing in the literature, based on the inclination of movement vectors along a cross-section to estimate the depth and geometry LSSs, is used for the first time while exploiting satellite interferometric data. Given the advent of satellite interferometric data and the related increasing availability of spatially dense and accurate measurements, we test the effectiveness of this method—here named the vector inclination method (VIM)—to four case landslides located in Italy characterized by different types of movement, kinematics and volume. Geotechnical and geophysical information of the LSS is used to validate the method. Our results show that each of the presented cases provides useful insight into the validity of VIM using satellite interferometric data. The main advantages of VIM applied to satellite interferometry are that it enables estimation of the LSS with a theoretical worldwide coverage, as well as with no need for onsite instrumentation or even direct access; however, a good density of measurement points in both ascending and descending geometry is necessary. The combined use of VIM and traditional investigations can provide a more accurate LSS model.

Cobalt-catalyzed alkylation of methyl-substituted N-heteroarenes with primary alcohols: direct access to functionalized N-heteroaromatics

2020 ◽  
Vol 56 (2) ◽  
pp. 249-252 ◽  
Author(s):  
Anju Mishra ◽  
Ambikesh D. Dwivedi ◽  
Sujan Shee ◽  
Sabuj Kundu
Keyword(s):  
Direct Access ◽  
Primary Alcohols ◽  
First Time

Cobalt-catalyzed alkylation of various methyl-substituted N-heteroarenes with alcohols is reported for the first time.

scholarly journals Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

2013 ◽  
Vol 9 ◽  
pp. 2537-2543 ◽  
Author(s):  
Yumeng Xi ◽  
Boliang Dong ◽  
Xiaodong Shi
Keyword(s):  
Vinyl Ether ◽  
Catalytic Amount ◽  
Direct Access ◽  
Vinyl Ethers ◽  
Ether Synthesis ◽  
First Time

Gold-catalyzed O-vinylation of cyclic 1,3-diketones has been achieved for the first time, which provides direct access to various vinyl ethers. A catalytic amount of copper triflate was identified as the significant additive in promoting this transformation. Both aromatic and aliphatic alkynes are suitable substrates with good to excellent yields.

scholarly journals Visualising Iron Gall Ink Underdrawings In 16th Century Paintings In-Situ By Micro-XRF Scanning (MA-XRF) And LED-Excited IRR (LEDE-IRR)

2022 ◽  
Author(s):  
Mareike Gerken ◽  
Jochen Sander ◽  
Christoph Krekel
Keyword(s):  
Cross Sections ◽  
Interdisciplinary Studies ◽  
Direct Access ◽  
Invasive Approach ◽  
X Ray ◽  
Non Invasive ◽  
Xrf Scanning ◽  
Iron Gall ◽  
Panel Paintings ◽  
First Time

Abstract Until today, iron gall ink is classified as an exceptional underdrawing material for paintings. A certain identification is always based on invasive analysis. This article presents a new non-destructive analysis approach using micro-X-ray fluorescence scanning (MA-XRF), LED-excited IRR (LEDE-IRR) using a narrow wavelength-range of infrared radiation (IR) and stereomicroscopy for visualising and identifying iron gall ink underdrawings. To assess possibilities and limits of this non-invasive approach, results were compared to invasive examinations on cross-sections using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). The approach is tested on panel paintings of Hans Holbein the Elder and Giovanni Battista Cima da Conegliano. The holistic setup could successfully visualise underdrawing lines made with iron gall inks, which formerly remained invisible by means of conventional IRR. For the first time, a direct access to a formerly invisible type of underdrawing is created, allowing to harness the whole iron gall ink underdrawing for interdisciplinary studies.

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