Lewis Acid-Assisted Reduction of Nitrite to Nitric and Nitrous Oxide via the Elusive Nitrite Radical Dianion

Reduction of nitrite anions [NO2]- takes place in a myriad of environments such as in the soil as part of the biogeochemical nitrogen cycle as well as in acidified nuclear waste. Nitrite reduction typically takes place within the coordination sphere of a redox active transition metal. Lewis acid coordination, however, can dramatically modify the reduction potential of this polyoxoanion to allow for reduction under non-aqueous conditions (-0.74 V vs. NHE). This strategy enables the isolation of a borane-capped nitrite dianion [NO2]2- along with its spectroscopic study consistent with reduction to the N(II) oxidation state. Protonation of the nitrite dianion results in facile loss of nitric oxide (NO) while reaction of the nitrite dianion with nitric oxide results in disproportionation to nitrous oxide (N2O) and nitrite, connecting three redox levels in the global nitrogen cycle.

Tailoring Atomically Dispersed Cobalt-Nitrogen Active Sites in Wrinkled Carbon Nanosheets via “Fence” Isolation for Highly Sensitive Detection of Hydrogen Peroxide

Stable and highly sensitive determination of hydrogen peroxide (H2O2) is needed in various fields ranging from disease prevention to environmental protection. The construction of inexpensive and highly active transition-metal-based nitrogen-doped...

Inactive status is an independent predictor of liver transplant waitlist mortality and is associated with a transplant centers median meld at transplant

Background Approximately 30% of patients on the liver transplant waitlist experience at least one inactive status change which makes them temporarily ineligible to receive a deceased donor transplant. We hypothesized that inactive status would be associated with higher mortality which may differ on a transplant centers’ or donor service areas’ (DSA) Median MELD at Transplant (MMaT). Methods Multi-state models were constructed (OPTN database;06/18/2013-06/08/2018) using DSA-level and transplant center-level data where MMaT were numerically ranked and categorized into tertiles. Hazards ratios were calculated between DSA and transplant center tertiles, stratified by MELD score, to determine differences in inactive to active transition probabilities. Results 7,625 (30.2% of sample registrants;25,216 total) experienced at least one inactive status change in the DSA-level cohort and 7,623 experienced at least one inactive status change in the transplant-center level cohort (30.2% of sample registrants;25,211 total). Inactive patients with MELD≤34 had a higher probability of becoming re-activated if they were waitlisted in a low or medium MMaT transplant center or DSA. Transplant rates were higher and lower re-activation probability was associated with higher mortality for the MELD 26–34 group in the high MMaT tertile. There were no significant differences in re-activation, transplant probability, or waitlist mortality for inactivated patients with MELD≥35 regardless of a DSA’s or center’s MMaT. Conclusion This study shows that an inactive status change is independently associated with waitlist mortality. This association differs by a centers’ and a DSAs’ MMaT. Prioritization through care coordination to resolve issues of inactivity is fundamental to improving access.

IMPROVING THE PROCESS OF MANAGING THE COST OF CONSTRUCTION OF AN OBJECT IN THE CONTEXT OF DIGITAL TRANSFORMATION OF THE INDUSTRY

Currently, there is an active transition of the investment and construction industry in the field of digitalization in many management processes. The main focus of the state is focused on the continuous process of managing information modeling technologies of a construction object at all stages of its life cycle, and the key element of this management process is the collection and publication of analytical data collected automatically by extracting the requested information from information systems about stages and critical points in urban development. Of particular importance is the automation of the process of managing the cost of the object and the creation of a unified information environment that takes into account possible factors of cost changes during the implementation of the construction object.

Density-Based Descriptors of Redox Reactions Involving Transition Metal Compounds as a Reality-Anchored Framework: A Perspective

Description of redox reactions is critically important for understanding and rational design of materials for electrochemical technologies, including metal-ion batteries, catalytic surfaces, or redox-flow cells. Most of these technologies utilize redox-active transition metal compounds due to their rich chemistry and their beneficial physical and chemical properties for these types of applications. A century since its introduction, the concept of formal oxidation states (FOS) is still widely used for rationalization of the mechanisms of redox reactions, but there exists a well-documented discrepancy between FOS and the electron density-derived charge states of transition metal ions in their bulk and molecular compounds. We summarize our findings and those of others which suggest that density-driven descriptors are, in certain cases, better suited to characterize the mechanism of redox reactions, especially when anion redox is involved, which is the blind spot of the FOS ansatz.

Bild und Spiegelbild: Kleiner Unterschied – große Auswirkungen

Henri Brunner, Looking Glass Chemistry: Small Differences—Gigantic Effects (Lives in Chemistry–Lebenswerke in der Chemie) “A different sort of chemistry is needed”. In 1966 this rather disconcerting thought led HENRI BRUNNER to create the hitherto unknown, optically active transition metal complexes—and so to his lifelong interest in image/mirror image molecules and other objects. Nowadays it is textbook knowledge that minute quantities of optically active transition metal complexes can act as catalysts to allow the synthesis of large quantities of organic and pharmaceutical products. In 1971 his outstanding chemistry resulted in his appointment as the youngest university professor in Germany and founder of the inorganic chemistry department in Regensburg. His mother always taught him to “Keep your eyes open”. Henri Brunner, born in 1935, did just that—whether he was drawing, playing chess, doing sports, collecting Colorado potato beetles, demonstrating, obtaining grants, teaching, appointing academic staff, or looking after his tie and snail collections – and he continues to do so aged 85+!

Density-based Descriptors of Redox Reactions Involving Transition Metal Compounds as a Reality-anchored Framework: A Perspective

Description of redox reactions is critically important for understanding and rational design of materials for electrochemical technologies including metal-ion batteries, catalytic surfaces, or redox-flow cells. Most of these technologies utilize redox-active transition metal compounds due to their rich chemistry and their beneficial physical and chemical properties for these types of applications. A century since its introduction, the concept of formal oxidation states (FOS) is still widely used for rationalization of the mechanisms of redox reactions, but there exists a well-documented discrepancy between FOS and the electron density-derived charge states of transition metal ions in their bulk and molecular compounds. We summarize our findings and those of others which suggest that density-driven descriptors are in certain cases better suited to characterize the mechanism of redox reactions, especially when anion redox is involved, which is the blind spot of the FOS ansatz.

RESEARCH OF THE EFFICIENCY OF MARINE DIESEL FUEL COOLING SYSTEM ON THE BASIS OF NEW REFRIGERANTS

The requirements of the International Maritime Organization, government environmental agencies and other non-governmental groups are aimed at reducing emissions of harmful substances into the environment during the operation of diesel engines. Among these substances, the most dangerous are sulfur oxide (SOx), nitrogen oxide (NOx) and particulate matter (PM). In accordance with the specified requirements, there is an active transition to fuels with ultra-low sulfur content. The use of these fuels in marine diesel engines is associated with a number of difficulties, because these engines are usually designed for operation on fuels with high viscosity and lubricity. The viscosity values for ultra-low sulfur fuels are close to the permitted minimums for diesel engines at normal engine room temperature. The greatest difficulties occur when the viscosity values fall below the specific range when the fuel temperature before the engine increases. For reliable operation of the engine, the fuel temperature must be constantly maintained at a range in which the fuel viscosity will have the required values. For this purpose the engine design provides presence of fuel cooling system with a water cooler and a chiller for heat removal from water. In this paper the efficiency of chiller refrigeration plant was investigated using new perspective refrigerant mixtures R125/R290 and R134a/R290 as working fluids in comparison with basic R134a and R22. The values of composition for both mixtures are chosen such that they are closest to the azeotrope. It is possible for azeotrope mixtures to minimize the temperature difference between heat exchanging medias in condenser and evaporator of refrigeration plant. During the investigation it was revealed that the values of refrigeration coefficient of refrigerating plant when using mixtures as working fluids were somewhat lower when operating on R134a and R22. But the values of volumetric refrigeration capacity with mixtures as working fluids are significantly higher.