Thermochemical destruction of carbon-filled plastic thermo-protective materials during inertial deposition of liquid burning active-metal agglomerates

1995 ◽  
Vol 31 (2) ◽  
pp. 188-192
Author(s):  
V. A. Burakov
Keyword(s):  
Active Metal ◽  
Thermochemical Destruction

Piperazine as an Inexpensive and Efficient Ligand for Pd-Catalyzed Homocoupling Reactions to Synthesize Bipyridines and Their Analogues

2019 ◽  
Vol 16 (1) ◽  
pp. 173-180
Author(s):  
Mingwei Chen ◽  
Jinyu Hu ◽  
Xiaoli Tang ◽  
Qiming Zhu
Keyword(s):  
Transition Metal ◽  
Oxidation State ◽  
Coupling Reaction ◽  
Aryl Halides ◽  
Metal Species ◽  
Good Substrate ◽  
Active Metal ◽  
Homocoupling Reaction ◽  
Catalytic Cycles ◽  
Reductive Homocoupling

Aim and Objective: The synthesis of bipyridines, especially 2, 2’-bipyridines, remains challenging because the catalytic cycle can be inhibited due to coordination of bipyridine to transition metal. Thus, the development of efficient methods for the synthesis of bipyridines is highly desirable. In the present work, we presented a promising approach for preparation of bipyridines via a Pd-catalyzed reductive homocoupling reaction with simple piperazine as a ligand. Materials and Methods: Simple and inexpensive piperazine was used as a ligand for Pd-catalyzed homocoupling reaction. The combination of Pd(OAc)2 and piperazine in dimethylformamide (DMF) was observed to form an excellent catalyst and efficiently catalyzed the homocoupling of azaarenyl halides, in which DMF was used as the solvent without excess reductants although stoichiometric reductant was generally required to generate the low-oxidation-state active metal species in the catalytic cycles. </P><P> Results: In this case, good to excellent yields of bipyridines and their (hetero) aromatic analogues were obtained in the presence of 2.5 mol% of Pd(OAc)2 and 5 mol% of piperazine, using K3PO4 as a base in DMF at 140°C. Conclusion: According to the results, piperazine as an inexpensive and efficient ligand was used in the Pd(OAc)2-catalyzed homocoupling reaction of heteroaryl and aryl halides. The coupling reaction was operationally simple and displayed good substrate compatibility.

Active metal single-sites based on metal–organic frameworks: construction and chemical prospects

2021 ◽  
Author(s):  
Yiyang Sun ◽  
Qiuzheng Du ◽  
Fangqi Wang ◽  
Pierre Dramou ◽  
Hua He
Keyword(s):  
Single Point ◽  
Metal Organic Frameworks ◽  
Design Strategy ◽  
Active Metal ◽  
Metal Organic

Metal single-point is a novel and potential design strategy that has been applied for the development of metal organic frameworks.

scholarly journals Efficient long-range conduction in cable bacteria through nickel protein wires

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Henricus T. S. Boschker ◽  
Perran L. M. Cook ◽  
Lubos Polerecky ◽  
Raghavendran Thiruvallur Eachambadi ◽  
Helena Lozano ◽  
...  
Keyword(s):  
Electron Transport ◽  
Long Range ◽  
Cell Envelope ◽  
Protein Structures ◽  
Chemical Imaging ◽  
Electrical Currents ◽  
Core Proteins ◽  
Active Metal ◽  
Unknown Form ◽  
High Resolution Microscopy

AbstractFilamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.

scholarly journals Nanozymes for Environmental Pollutant Monitoring and Remediation

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 408
Author(s):  
Elicia L. S. Wong ◽  
Khuong Q. Vuong ◽  
Edith Chow
Keyword(s):  
Real Time ◽  
Organic Pollutants ◽  
Architectural Design ◽  
Electrochemical Techniques ◽  
Environmental Pollutant ◽  
Field Application ◽  
Optical Methods ◽  
Enzyme Mimicking ◽  
Active Metal ◽  
Recent Developments

Nanozymes are advanced nanomaterials which mimic natural enzymes by exhibiting enzyme-like properties. As nanozymes offer better structural stability over their respective natural enzymes, they are ideal candidates for real-time and/or remote environmental pollutant monitoring and remediation. In this review, we classify nanozymes into four types depending on their enzyme-mimicking behaviour (active metal centre mimic, functional mimic, nanocomposite or 3D structural mimic) and offer mechanistic insights into the nature of their catalytic activity. Following this, we discuss the current environmental translation of nanozymes into a powerful sensing or remediation tool through inventive nano-architectural design of nanozymes and their transduction methodologies. Here, we focus on recent developments in nanozymes for the detection of heavy metal ions, pesticides and other organic pollutants, emphasising optical methods and a few electrochemical techniques. Strategies to remediate persistent organic pollutants such as pesticides, phenols, antibiotics and textile dyes are included. We conclude with a discussion on the practical deployment of these nanozymes in terms of their effectiveness, reusability, real-time in-field application, commercial production and regulatory considerations.

scholarly journals Anodic Stripping Voltammetry with the Hanging Mercury Drop Electrode for Trace Metal Detection in Soil Samples

Chemosensors ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 107
Author(s):  
Kequan Xu ◽  
Clara Pérez-Ràfols ◽  
Amine Marchoud ◽  
María Cuartero ◽  
Gastón A. Crespo
Keyword(s):  
Metal Ions ◽  
Limit Of Detection ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Redox Active ◽  
Active Metal ◽  
Metal Detection ◽  
Trace Metal Detection

The widely spread use of the hanging mercury drop electrode (HMDE) for multi-ion analysis is primarily ascribed to the following reasons: (i) excellent reproducibility owing to the easy renewal of the electrode surface avoiding any hysteresis effect (i.e., a new identical drop is generated for each measurement to be accomplished); (ii) a wide cathodic potential window originating from the passive hydrogen evolution and solvent electrolysis; (iii) the ability to form amalgams with many redox-active metal ions; and (iv) the achievement of (sub)nanomolar limits of detection. On the other hand, the main controversy of the HMDE usage is the high toxicity level of mercury, which has motivated the scientific community to question whether the HMDE deserves to continue being used despite its unique capability for multi-metal detection. In this work, the simultaneous determination of Zn2+, Cd2+, Pb2+, and Cu2+ using the HMDE is investigated as a model system to evaluate the main features of the technique. The analytical benefits of the HMDE in terms of linear range of response, reproducibility, limit of detection, proximity to ideal redox behavior of metal ions and analysis time are herein demonstrated and compared to other electrodes proposed in the literature as less-toxic alternatives to the HMDE. The results have revealed that the HMDE is largely superior to other reported methods in several aspects and, moreover, it displays excellent accuracy when simultaneously analyzing Zn2+, Cd2+, Pb2+, and Cu2+ in such a complex matrix as digested soils. Yet, more efforts are required towards the definitive replacement of the HMDE in the electroanalysis field, despite the elegant approaches already reported in the literature.

Nonlinear optical properties and markedly higher two photon absorption of ordered c-shaped plasmon-active metal nanostructures

2021 ◽  
Vol 112 ◽  
pp. 110695
Author(s):  
J. Švanda ◽  
Y. Kalachyova ◽  
A. Ajami ◽  
W. Husinsky ◽  
P. Macháč ◽  
...  
Keyword(s):  
Optical Properties ◽  
Nonlinear Optical ◽  
Nonlinear Optical Properties ◽  
Photon Absorption ◽  
Metal Nanostructures ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Active Metal

Effect of high temperature cycling on both crack formation in ceramics and delamination of copper layers in silicon nitride active metal brazing substrates

2017 ◽  
Vol 43 (6) ◽  
pp. 5080-5088 ◽  
Author(s):  
Hiroyuki Miyazakia ◽  
Shoji Iwakiri ◽  
Kiyoshi Hirao ◽  
Shinji Fukuda ◽  
Noriya Izu ◽  
...  
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Crack Formation ◽  
Temperature Cycling ◽  
Active Metal

scholarly journals Application of scanning probe energy loss spectroscopy to SERS-active metal nanostructures

2021 ◽  
Vol 1866 (1) ◽  
pp. 012006
Author(s):  
M Beshr ◽  
G Amarandei ◽  
A D Meade ◽  
R E Palmer ◽  
S Murphy
Keyword(s):  
Energy Loss ◽  
Scanning Probe ◽  
Metal Nanostructures ◽  
Active Metal

MRI‐Active Metal‐Organic Frameworks: Concepts for the Translation from Lab to Clinic

2021 ◽  
pp. 2100067
Author(s):  
Michael Peller ◽  
Arianna Lanza ◽  
Stefan Wuttke
Keyword(s):  
Metal Organic Frameworks ◽  
Active Metal ◽  
Metal Organic

Influence of Active Metal Precursors on the Structure and Catalytic Behavior of Pd/Al2O3 Catalysts for Selective Acetylene Hydrogenation

2021 ◽  
Author(s):  
Tianxing Yang ◽  
Min Zhao ◽  
Xue Wang ◽  
Rui Ma ◽  
Yanan Liu ◽  
...  
Keyword(s):  
Acetylene Hydrogenation ◽  
Catalytic Behavior ◽  
Metal Precursors ◽  
Active Metal
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