scholarly journals SuFEx-Enabled, Chemoselective Synthesis of Triflates, Triflamides and Triflimidates

2022 ◽  
Author(s):  
Bing-Yu Li ◽  
Lauren Voets ◽  
Ruben Van Lommel ◽  
Fien Hoppenbrouwers ◽  
Mercedes Alonso ◽  
...  

Sulfur(VI) Fluoride Exchange (SuFEx) chemistry has emerged as a next-generation click reaction, designed to assemble functional molecules quickly and modularly. Here, we report the ex situ generation of trifluoromethanesulfonyl fluoride...

2020 ◽  
Vol 21 (5) ◽  
pp. 785-793
Author(s):  
Marina B. Blanco ◽  
Lydia K. Greene ◽  
Fidisoa Rasambainarivo ◽  
Elizabeth Toomey ◽  
Rachel C. Williams ◽  
...  

Abstract Madagascar is a biodiversity hotspot that is facing rapid rates of deforestation, habitat destruction, and poverty. Urgent action is required to document the status of biodiversity to facilitate efficacious conservation plans. With the recent advent of portable and affordable genetic technologies, it is now possible to take genomic approaches out of the lab and into the field. Mobile genetics labs can produce scientifically reproducible data under field conditions, dramatically minimizing the time between sample collection and data analysis. Here, we show “proof of concept” by deploying miniPCR bio’s miniaturized thermal cycler alongside Oxford Nanopore’s MinION DNA sequencer in Madagascar. Specifically, we deployed this technology at Anjajavy, northwestern Madagascar for rapid biodiversity assessment. We successfully extracted mouse lemur DNA, amplified and sequenced a phylogenetically informative mitochondrial gene (cytochrome-b; cytb), and thereby confirmed the presence of Danfoss’ mouse lemur (M. danfossi) within the Anjajavy Reserve. We show that a mobile genetics lab can provide expeditious results, and allow scientists to conduct genetic analyses, potentially allowing for rapid interventions under emergency conditions in situ. Additionally, mobile labs offer powerful training opportunities for in-country scientists for whom training opportunities were previously confined to ex-situ locations. By bringing genomic technologies to Madagascar and other economically challenged and biodiverse regions of the world, the next generation of scientists and conservationists can more fully implement their leadership roles. Local laboratory and training facilities are changing the polarity of research programs in Madagascar and empowering national researchers to take charge of environmental stewardship.


2018 ◽  
Author(s):  
Narinder Singh ◽  
Shuangye Wu ◽  
W. John Raupp ◽  
Sunish Sehgal ◽  
Sanu Arora ◽  
...  

ABSTRACTGenebanks are valuable resources for crop improvement through the acquisition, ex-situ conservation and sharing of unique germplasm among plant breeders and geneticists. With over seven million existing accessions and increasing storage demands and costs, genebanks need efficient characterization and curation to make them more accessible and usable and to reduce operating costs, so that the crop improvement community can most effectively leverage this vast resource of untapped novel genetic diversity. However, the sharing and inconsistent documentation of germplasm often results in unintentionally duplicated collections with poor characterization and many identical accessions that can be hard or impossible to identify without passport information and unmatched accession identifiers. Here we demonstrate the use of genotypic information from these accessions using a cost-effective next generation sequencing platform to find and remove duplications. We identify and characterize over 50% duplicated accessions both within and across genebank collections of Aegilops tauschii, an important wild relative of wheat and source of genetic diversity for wheat improvement. We present a pipeline to identify and remove identical accessions within and among genebanks and curate globally unique accessions. We also show how this approach can also be applied to future collection efforts to avoid the accumulation of identical material. When coordinated across global genebanks, this approach will ultimately allow for cost effective and efficient management of germplasm and better stewarding of these valuable resources.


Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.


Author(s):  
K. Barmak

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.


Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.


Author(s):  
M. E. Twigg ◽  
B. R. Bennett ◽  
J. R. Waterman ◽  
J. L. Davis ◽  
B. V. Shanabrook ◽  
...  

Recently, the GaSb/InAs superlattice system has received renewed attention. The interest stems from a model demonstrating that short period Ga1-xInxSb/InAs superlattices will have both a band gap less than 100 meV and high optical absorption coefficients, principal requirements for infrared detector applications. Because this superlattice system contains two species of cations and anions, it is possible to prepare either InSb-like or GaAs-like interfaces. As such, the system presents a unique opportunity to examine interfacial properties.We used molecular beam epitaxy (MBE) to prepare an extensive set of GaSb/InAs superlattices grown on an GaSb buffer, which, in turn had been grown on a (100) GaAs substrate. Through appropriate shutter sequences, the interfaces were directed to assume either an InSb-like or GaAs-like character. These superlattices were then studied with a variety of ex-situ probes such as x-ray diffraction and Raman spectroscopy. These probes confirmed that, indeed, predominantly InSb-like and GaAs-like interfaces had been achieved.


2004 ◽  
Vol 171 (4S) ◽  
pp. 389-389
Author(s):  
Manoj Monga ◽  
Ramakrishna Venkatesh ◽  
Sara Best ◽  
Caroline D. Ames ◽  
Courtney Lee ◽  
...  

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