scholarly journals Nanoengineered chiral Pt-Ir alloys for high-performance enantioselective electrosynthesis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sopon Butcha ◽  
Sunpet Assavapanumat ◽  
Somlak Ittisanronnachai ◽  
Veronique Lapeyre ◽  
Chularat Wattanakit ◽  
...  
Keyword(s):  
High Performance ◽  
Electrochemical Stability ◽  
Lyotropic Liquid Crystal ◽  
Crucial Importance ◽  
Chiral Compound ◽  
Enantiomerically Pure ◽  
Chiral Compounds ◽  
The Past ◽  
Pure Compounds ◽  
Potential Applications

AbstractThe design of efficient chiral catalysts is of crucial importance since it allows generating enantiomerically pure compounds. Tremendous efforts have been made over the past decades regarding the development of materials with enantioselective properties for various potential applications ranging from sensing to catalysis and separation. Recently, chiral features have been generated in mesoporous metals. Although these monometallic matrices show interesting enantioselectivity, they suffer from rather low stability, constituting an important roadblock for applications. Here, a straightforward strategy to circumvent this limitation by using nanostructured platinum-iridium alloys is presented. These materials can be successfully encoded with chiral information by co-electrodeposition from Pt and Ir salts in the simultaneous presence of a chiral compound and a lyotropic liquid crystal as asymmetric template and mesoporogen, respectively. The alloys enable a remarkable discrimination between chiral compounds and greatly improved enantioselectivity when used for asymmetric electrosynthesis (>95 %ee), combined with high electrochemical stability.

scholarly journals Altering the Stereoselectivity of Whole-Cell Biotransformations via the Physicochemical Parameters Impacting the Processes

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 781
Author(s):  
Agnieszka Raczyńska ◽  
Joanna Jadczyk ◽  
Małgorzata Brzezińska-Rodak
Keyword(s):  
Culture Conditions ◽  
Biologically Active ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
Chiral Compounds ◽  
Physicochemical Factors ◽  
Pure Compounds ◽  
Genetic Level ◽  
Prochiral Ketones ◽  
Optically Pure

The enantioselective synthesis of organic compounds is one of the great challenges in organic synthetic chemistry due to its importance for the acquisition of biologically active derivatives, e.g., pharmaceuticals, agrochemicals, and others. This is why biological systems are increasingly applied as tools for chiral compounds synthesis or modification. The use of whole cells of “wild-type” microorganisms is one possible approach, especially as some methods allow improving the conversion degrees and controlling the stereoselectivity of the reaction without the need to introduce changes at the genetic level. Simple manipulation of the culture conditions, the form of a biocatalyst, or the appropriate composition of the biotransformation medium makes it possible to obtain optically pure products in a cheap, safe, and environmentally friendly manner. This review contains selected examples of the influence of physicochemical factors on the stereochemistry of the biocatalytic preparation of enantiomerically pure compounds, which is undertaken through kinetically controlled separation of their racemic mixtures or reduction of prochiral ketones and has an effect on the final enantiomeric purity and enantioselectivity of the reaction.

Preparation of high-performance PEEK anti-wear blends with melt-processable PTFE

2019 ◽  
Vol 32 (6) ◽  
pp. 645-654
Author(s):  
Xiaotao Qiu ◽  
Congli Fu ◽  
Aiqun Gu ◽  
Yang Gao ◽  
Xiuli Wang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Wear Resistance ◽  
Surface Analysis ◽  
Tribological Properties ◽  
High Performance ◽  
Tribological Performance ◽  
Mechanical And Tribological Properties ◽  
The Past ◽  
Wide Range ◽  
Potential Applications

High-performance anti-wear polyetheretherketone/polytetrafluoroethylene (PEEK/PTFE) blends have drawn much attention over the past few years, owing to their wide range of potential applications. However, a convenient and effective method to prepare such blends with superior mechanical and tribological properties is still lacking. In this work, we propose a promising approach that uses melt-processable PTFE (MP PTFE), instead of conventional PTFE, to prepare anti-wear blends. MP PTFE, with melt flow abilities under appropriate conditions, can disperse homogeneously in PEEK, enhancing both the mechanical and tribological properties of the PEEK/PTFE blend. To prove this postulation, in this work, both MP PTFE and commercial PTFE were blended with PEEK, separately, and the effects of PTFE type and content on the tensile and tribological properties of the blends were studied. The results showed that, although the addition of commercial PTFE to PEEK could increase the wear resistance, it decreased the tensile strength of PEEK significantly. Compared to the blends with commercial PTFE, the blends with MP PTFE exhibited better tribological performance and higher tensile strength for PTFE content below 10 wt%. It was confirmed that the better dispersion of MP PTFE in PEEK endowed the blends with higher tensile strength. The surface analysis indicated that the MP PTFE could readily migrate to and enrich the surfaces of the blends. The relatively high PTFE content on the surface favored the formation of tribo-films, enhancing the tribological properties of the blends.

scholarly journals Bioreduction of α,β-unsaturated carbonyl compounds by Lasiodiplodia pseudotheobromae, endophytic fungus from Morinda citrifolia (RUBIACEAE)

2020 ◽  
Vol 9 (10) ◽  
pp. e9739109419
Author(s):  
Mark Carvalho da Silva ◽  
Maricelia Lopes dos Anjos ◽  
Luana Cardoso de Oliveira ◽  
Patrícia Santana Barbosa Marinho ◽  
Alessandra Keiko Nakasone ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carbonyl Compounds ◽  
High Performance ◽  
Room Temperature ◽  
Morinda Citrifolia ◽  
Enantiomerically Pure ◽  
Food Industries ◽  
Pure Compounds ◽  
Layer Chromatography ◽  
Orbital Shaker

Biotransformations are reactions carried out by microorganisms that lead to changes in the structures of organic compounds, among the biotransformations there are bioreductions. Bioreductions are of great interest to the pharmaceutical and food industries, as they almost always lead to the formation of enantiomerically pure compounds. Thus, this work aimed to verify the ability of the fungus Lasiodiplodia pseudotheobromae in bioreduce α,β-unsaturated carbonyl compounds. Compounds (3E)-4-(2-methoxy-phenyl)-but-3-en-2-one (1), (1E, 4E)-1,5-diphenyl-pent-1,4-dien-3-one (2) and (1E, 4E)-1,5-bis-(2-methoxy-phenyl)-penta-1,4-dien-3-one (3) were used as substrates. The reactions were carried out on an orbital shaker for 8 days at room temperature. The products formed were characterized by analytical thin layer chromatography (ATLC), high performance liquid chromatography (HPLC) and hydrogen nuclear magnetic resonance (1H NMR). For all products formed was observed reduction in double bonds C=C and C=O leading to the formation of the respective alcohols. This is the first report of biotransformation reactions using the fungus Lasiodiplodia pseudotheobromae.

scholarly journals Characterization of Exopolysaccharides Produced by Rhizobia Species

2015 ◽  
Vol 39 (6) ◽  
pp. 1566-1575 ◽  
Author(s):  
Tereza Cristina Luque Castellane ◽  
Alda Maria Machado Bueno Otoboni ◽  
Eliana Gertrudes de Macedo Lemos
Keyword(s):  
High Performance ◽  
Biological Properties ◽  
Reversed Phase ◽  
The Past ◽  
Structure And Dynamics ◽  
Key Factor ◽  
Reactive Groups ◽  
Potential Applications ◽  
Species Specific

ABSTRACT Increasing attention has been given, over the past decades, to the production of exopolysaccharides (EPS) from rhizobia, due to their various biotechnological applications. Overall characterization of biopolymers involves evaluation of their chemical, physical, and biological properties; this evaluation is a key factor in understanding their behavior in different environments, which enables researchers to foresee their potential applications. Our focus was to study the EPS produced by Mesorhizobium huakuii LMG14107, M. loti LMG6125, M. plurifarium LMG11892,Rhizobium giardini bv. giardiniH152T, R. mongolense LMG19141, andSinorhizobium (= Ensifer)kostiense LMG19227 in a RDM medium with glycerol as a carbon source. These biopolymers were isolated and characterized by reversed-phase high-performance liquid chromatography (RP-HPLC), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopies. Maximum exopolysaccharide production was 3.10, 2.72, and 2.50 g L-1for the strains LMG6125, LMG19227, and LMG19141, respectively. The purified EPS revealed prominent functional reactive groups, such as hydroxyl and carboxylic, which correspond to a typical heteropolysaccharide. The EPS are composed primarily of galactose and glucose. Minor components found were rhamnose, glucuronic acid, and galacturonic acid. Indeed, from the results of techniques applied in this study, it can be noted that the EPS are species-specific heteropolysaccharide polymers composed of common sugars that are substituted by non-carbohydrate moieties. In addition, analysis of these results indicates that rhizobial EPS can be classified into five groups based on ester type, as determined from the 13C NMR spectra. Knowledge of the EPS composition now facilitates further investigations relating polysaccharide structure and dynamics to rheological properties.

scholarly journals Fano-Resonance in Hybrid Metal-Graphene Metamaterial and Its Application as Mid-Infrared Plasmonic Sensor

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 268 ◽  
Author(s):  
Jianfa Zhang ◽  
Qilin Hong ◽  
Jinglan Zou ◽  
Yuwen He ◽  
Xiaodong Yuan ◽  
...  
Keyword(s):  
Fano Resonance ◽  
High Performance ◽  
Figure Of Merit ◽  
Plasmonic Sensor ◽  
Resonance Strength ◽  
Mid Infrared ◽  
Graphene Layers ◽  
The Past ◽  
Potential Applications ◽  
Hybrid Metamaterial

Fano resonances in nanostructures have attracted widespread research interests in the past few years for their potential applications in sensing, switching and nonlinear optics. In this paper, a mid-infrared Fano resonance in a hybrid metal-graphene metamaterial is studied. The hybrid metamaterial consists of a metallic grid enclosing with graphene nanodisks. The Fano resonance arises from the coupling of graphene and metallic plasmonic resonances and it is sharper than plasmonic resonances in pure graphene nanostructures. The resonance strength can be enhanced by increasing the number of graphene layers. The proposed metamaterial can be employed as a high-performance mid-infrared plasmonic sensor with an unprecedented sensitivity of about 7.93 μm/RIU and figure of merit (FOM) of about 158.7.

Analytical and Preparative Scale Separation of Enantiomers of Chiral Drugs by Chromatography and Related Methods

2018 ◽  
Vol 25 (33) ◽  
pp. 4152-4188 ◽  
Author(s):  
Mehmet Gumustas ◽  
Sibel A. Ozkan ◽  
Bezhan Chankvetadze
Keyword(s):  
Capillary Electrochromatography ◽  
High Performance ◽  
Analytical Techniques ◽  
Chiral Separations ◽  
Chiral Drugs ◽  
Preparative Scale ◽  
Enantiomerically Pure ◽  
Separation Of Enantiomers ◽  
Chiral Compounds ◽  
Chiral Pharmaceuticals

While the amino acids, enzymes and hormones are chiral, chirality plays significant role in the life of plants, animals, as well as the human being. Chirality of molecules is important in various industries, such as pharmaceutical, agricultural, food, electronics, etc. Chiral drugs may have different bioavailability, distribution, biotransformation and excretion, as well as quantitatively and/or qualitatively different pharmacological or toxic properties. Enantiomerically pure chiral drugs have been increasingly developed for the pharmaceutical market due to their superiority from the viewpoints of potency and safety. This is supported by the development of new methods for enantioselective production of the chiral compounds, as well as by the capability of the enantioselective analytical methods to allow a detection and quantification of minor enantiomeric impurity in the presence of another enantiomer in a large excess. The aim of the present review is to provide a short summary of the basic principles of chiral separations on an analytical and preparative scale. In addition, some selected applications for analytical techniques, such as gas chromatography, supercritical fluid chromatography, high performance liquid chromatography, capillary electrophoresis and capillary electrochromatography for the separation of enantiomers of chiral pharmaceuticals published in the last two years are also discussed.

Progress and perspectives on halide lithium conductors for all-solid-state lithium batteries

2020 ◽  
Vol 13 (5) ◽  
pp. 1429-1461 ◽  
Author(s):  
Xiaona Li ◽  
Jianwen Liang ◽  
Xiaofei Yang ◽  
Keegan R. Adair ◽  
Changhong Wang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Solid State ◽  
Lithium Batteries ◽  
Electrochemical Stability ◽  
Superionic Conductors ◽  
Fundamental Understanding ◽  
Potential Applications ◽  
Synthesis Routes

This review focuses on fundamental understanding, various synthesis routes, chemical/electrochemical stability of halide-based lithium superionic conductors, and their potential applications in energy storage as well as related challenges.

Electrochemical Deposition of Polypyrrole Nanostructures for Energy Applications: A Review

2020 ◽  
Vol 16 (4) ◽  
pp. 462-477 ◽  
Author(s):  
Patrizia Bocchetta ◽  
Domenico Frattini ◽  
Miriana Tagliente ◽  
Filippo Selleri
Keyword(s):  
Lithium Batteries ◽  
High Performance ◽  
Relevant Literature ◽  
Chemical Parameters ◽  
Energy Devices ◽  
Energy Applications ◽  
Physico Chemical ◽  
Potential Applications ◽  
Template Free ◽  
Cathodic Polymerization

By collecting and analyzing relevant literature results, we demonstrate that the nanostructuring of polypyrrole (PPy) electrodes is a crucial strategy to achieve high performance and stability in energy devices such as fuel cells, lithium batteries and supercapacitors. In this critic and comprehensive review, we focus the attention on the electrochemical methods for deposition of PPy, nanostructures and potential applications, by analyzing the effect of different physico-chemical parameters, electro-oxidative conditions including template-based or template-free depositions and cathodic polymerization. Diverse interfaces and morphologies of polymer nanodeposits are also discussed.

Performance Management Transformation

2020 ◽  
Keyword(s):  
Organizational Performance ◽  
Performance Management ◽  
High Performance ◽  
Best Practice ◽  
Call To Action ◽  
Daily Work ◽  
The Past ◽  
Great Debate ◽  
The Subject ◽  
New Research

No other talent process has been the subject of such great debate and emotion as performance management (PM). For decades, different strategies have been tried to improve PM processes, yielding an endless cycle of reform to capture the next “flavor-of-the-day” PM trend. The past 5 years, however, have brought novel thinking that is different from past trends. Companies are reducing their formal processes, driving performance-based cultures, and embedding effective PM behavior into daily work rather than relying on annual reviews to drive these. Through case studies provided from leading organizations, this book illustrates the range of PM processes that companies are using today. These show a shift away from adopting someone else’s best practice; instead, companies are designing bespoke PM processes that fit their specific strategy, climate, and needs. Leading PM thought leaders offer their views about the state of PM today, what we have learned and where we need to focus future efforts, including provocative new research that shows what matters most in driving high performance. This book is a call to action for talent management professionals to go beyond traditional best practice and provide thought leadership in designing PM processes and systems that will enhance both individual and organizational performance.

scholarly journals Organic magnetoelectric and optomagnetic couplings: perspectives for organic spin optoelectronics

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Zhongxuan Wang ◽  
Wei Qin
Keyword(s):  
Ferromagnetic Materials ◽  
The Past ◽  
Potential Applications ◽  
Further Development

AbstractOver the past years, the development of organic ferromagnetic materials has been investigated worldwide for potential applications. Due to the couplings among the charge, orbit, spin, and phonon in organic ferromagnetic materials, magnetoelectric, and optomagnetic couplings have been realized and observed. In this review, progress in organic magnetoelectric and optomagnetic couplings is presented, and the mechanisms behind the phenomena are also briefly summarized. Hopefully, the understanding of magnetoelectric and optomagnetic couplings could provide guidance for the further development of organic spin optoelectronics.

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