Monthly Archives: September 2023

Access to High‐Purity 7mG‐cap RNA in Substantial Quantities by a Convenient All‐Chemical Solid‐Phase Method

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Access to High-Purity 7mG-cap RNA in Substantial Quantities by a Convenient All-Chemical Solid-Phase Method

A practical and valuable all-chemical method has been developed to synthesize 5’-7mGppp RNA on solid-support without damaging the 7mG-cap or the RNA during RNA deprotection and release from the support under mild basic conditions. Substantial quantities of high-purity 5’-7mGppp RNA are thus affordable as useful research tools.


Abstract

Given the importance of mRNA with 5’-cap, easy access to RNA substrates with different 7mG caps, of high quality and in large quantities is essential to elucidate the roles of RNA and the regulation of underlying processes. In addition to existing synthetic routes to 5’-cap RNA based on enzymatic, chemical or chemo-enzymatic methods, we present here an all-chemical method for synthetic RNA capping. The novelty of this study lies in the fact that the capping reaction is performed on solid-support after automated RNA assembly using commercial 2’-O-propionyloxymethyl ribonucleoside phosphoramidites, which enable final RNA deprotection under mild conditions while preserving both 7mG-cap and RNA integrity. The capping reaction is efficiently carried out between a 5’-phosphoroimidazolide RNA anchored on the support and 7mGDP in DMF in the presence of zinc chloride. Substantial amounts of 7mG-cap RNA (from 1 to 28 nucleotides in length and of any sequence with or without internal methylations) containing various cap structures (7mGpppA, 7mGpppAm, 7mGpppm6A, 7mGpppm6Am, 7mGpppG, 7mGpppGm) were obtained with high purity after IEX-HPLC purification. This capping method using solid-phase chemistry is convenient to perform and provides access to valuable RNA substrates as useful research tools to unravel specific issues regarding cap-related processes.

Terpenoids as Human Neutrophil Elastase (HNE) Inhibitors: A Comprehensive Review of Natural Anti‐inflammatory Isoprenoids

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Terpenoids as Human Neutrophil Elastase (HNE) Inhibitors: A Comprehensive Review of Natural Anti-inflammatory Isoprenoids

The information on the potential therapeutic effects of terpenoids reviewed here should help to guide researchers in the development of safer and more effective drugs derived from natural terpenoid compounds for managing inflammatory problems.


Abstract

Human neutrophil elastase (HNE) is an enzyme that plays a key role in the body‘s inflammatory response. It has been linked to several diseases such as chronic obstructive pulmonary disease (COPD), emphysema, and cystic fibrosis. As potential treatments for these diseases, HNE inhibitors are of great interest. Metabolites derived from plants, particularly terpenoids such as β-caryophyllene found in black pepper and other plants, and geraniol present in several essential oils, are recognized as significant sources of inhibitors for HNE. Because of their ability to inhibit HNE, terpenoids are considered promising candidates for developing novel therapies to treat inflammatory conditions such as COPD and emphysema. Furthermore, nature can serve as an excellent designer, and it may offer a safer drug candidate for inhibiting HNE production and activity in the future. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses were searched to get relevant and up-to-date literature on terpenoids as human neutrophil elastase inhibitors. This review focuses on the isolation, chemical diversity, and inhibition of human neutrophil elastase (HNE) of various terpenoids reported from natural sources up to 2022. A total of 251 compounds from various terpenoids classes have been reported. Further, it also provides a summary of HNE inhibitors and includes a thorough discussion on the structure-activity relationship.

Strong Metal‐support Interactions in Photocatalysis: Fundamentals and Design Methods

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Strong Metal-support Interactions in Photocatalysis: Fundamentals and Design Methods

This review focuses on recent efforts to enhance photocatalytic activities of metal nanoparticle-mediated photocatalysts through “strong metal-support interaction” (SMSI). Herein, we discuss the fundamentals of “strong metal-support interaction” and the methodology to practice the concept, involving synthesis and characterization techniques. The strengths and limitations of SMSI are also discussed, thus outlining future perspectives.


Abstract

Engineering the composition and geometry of metallic sites has become a popular manner to boost reaction rate and control reaction selectivity in heterogeneous catalysis. Many studies have been devoted to enhancing the stability of metallic nanoparticles during catalytic reactions by dispersion on metal oxide supports such as TiO2, CeO2 or Nb2O5. These supports not only modulate electronic properties and dispersion/stabilization of metallic nanoparticle but also influence catalytic selectivity, resulting in the so-called “strong metal-support interaction” (SMSI). In this minireview, we outlined the discovery and fundamentals of SMSI, as well as its extensive development over years. In addition, we summarized recent approaches developed to induce the construction of SMSI between different metal nanoparticles and metal oxide supports. Associated characterization microscopic and spectroscopic techniques were emphasized. Despite being a prevalent concept in catalysis, the number of studies on SMSI in heterogeneous photocatalysis has been even in limitation. Herein, we highlighted the beneficial effects of SMSI on boosting photocatalytic activity for CO2 reduction and H2 evolution reactions. In general, despite some controversial aspects of the SMSI, this concept offers wide opportunities ahead and encourages researchers to rethink the local active site localization and photocatalyst design.

Stability of Bipolar Plate Materials for Proton‐Exchange Membrane Water Electrolyzers: Dissolution of Titanium and Stainless Steel in DI Water and Highly Diluted Acid

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Stability of Bipolar Plate Materials for Proton-Exchange Membrane Water Electrolyzers: Dissolution of Titanium and Stainless Steel in DI Water and Highly Diluted Acid

We studied the stability of bipolar plate materials on-line. To mimic application-near conditions, we measured in deionized water and 0.5 mM H2SO4. For titanium, the dissolution is negligible, whereas for stainless steel 316L notable dissolution is detected. Yet, it remained below the reported poisoning limit for Nafion-based proton exchange membranes.


Abstract

The widespread use of proton exchange membrane water electrolyzers (PEMWE) is hindered by their high cost, of which a colossal factor is caused by the bipolar plates (BPP). In this paper, we investigate the stability of two BPP materials on-line with an optimized scanning flow cell setup coupled to an inductively coupled plasma mass spectrometer (SFC-ICP-MS), as well as scanning electron microscopy (SEM). The stability of currently used titanium and a cheaper alternative, stainless steel (SS) 316L, were characterized in deionized (DI) water and 0.5 mM H2SO4 to mimic the conditions at the BPP under operation. We show that the dissolution of Ti is negligible, whereas SS 316L degrades notably. Here, besides pH, the applied potentials play a crucial role. Nonetheless, even for the highest measured dissolution rate of SS 316L, the contamination in a full cell is estimated to remain below 1 ppm. This work illustrates the capabilities of on-line high-throughput stability tests for BPP materials and could therefore contribute towards optimization of cost-effective PEMWE.

Excellent MCM‐49 Supported CeCuOx Nanocatalyst with Ultrawide Operating Temperature Window and Strong Anti‐Alkali Ability for NH3‐SCR

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Excellent MCM-49 Supported CeCuOx Nanocatalyst with Ultrawide Operating Temperature Window and Strong Anti-Alkali Ability for NH3-SCR

Schematic diagram of the dominant mechanism of NH3-SCR reaction on CeCu/MCM-49 catalyst before and after poisoning. The L−H mechanism was dominant before poisoning. However, after alkali metal poisoning, NOx adsorption on the catalyst is inhibited, so the E−R mechanism dominates.


Abstract

NOx is a common atmospheric pollutant, and NH3-SCR technology efficiently purifies it. CeCuOx binary-oxide nanoparticles were synthesized and loaded onto acid MCM-49 molecular sieve with a large specific surface area to increase acid sites and disperse active sites of the catalyst. The optimized 35 % CeCu/MCM-49 catalyst effectively purified over 80 % of NOx in the temperature range of 200–500 °C and demonstrated excellent resistance to alkali metals, such as K, Na, and Ca. Even after K poisoning, it still removed over 80 % of NOx in the range of 200–450 °C. Various characterization methods, including XRD, FT-IR, TEM, and N2 isotherm adsorption-desorption tests, confirmed the structure of the catalyst remained intact after poisoning with no substance change, nor agglomeration of nanoparticles. NH3-TPD and H2-TPR confirmed that the catalyst had effective acidity and redox capacity that were not affected by alkali metals. In-situ DRIFTs showed that the catalytic reaction predominant mechanism shifted from L−H to E−R mechanism after poisoning. This study provides valuable insights into the development of high-performance Ce-based NH3-SCR catalysts with alkali metal resistance.

A strategy for improving the efficiency of boronic acid catalysis in the synthesis of amides.

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This study outlines the development of novel boronic acids as catalysts for the direct synthesis of amides from carboxylic acids and amines. The Lewis acidity of the boronic acids was estimated by means of computational techniques, and the observed increase in catalytic activity was corroborated by kinetic data derived from a model reaction. Our investigations led to the discovery of a set of ortho-(sulfonyloxy)benzeneboronic acids that compared favorably with the established state-of-the-art. These newly developed catalysts demonstrated efficacy in the coupling of aliphatic, aromatic, and heteroaromatic acids, as well as primary and secondary amines.

Model‐Assisted Interpretation of 4,4′‐Methylene Dianiline Adsorption on Soils at Micromolar Concentrations

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Abstract

Adsorption kinetics and isotherms were determined for 4,4′-methylene dianiline (MDA) on five diverse soils at nominal concentrations of 0.01–1.0 mg L−1 (nominal soil loading 0.1–40 μg gs −1). The data were used to model the adsorption process based on the two-step mechanism that is characteristic of the adsorption of aromatic amines, consisting of a physical equilibrium between the aqueous phase and the soil organic matter and a chemical reaction between the adsorbed MDA and reactive sites in the soil organic matter. Generic parameters were determined that enabled application of the model to other soils, which was checked against previously published data for MDA adsorption. At the low concentrations evaluated, the adsorption process took place almost exclusively in the organic matter without the need to account for a separate ion exchange process with the soil mineral fraction. Physical adsorption was found to be mainly dependent on the protonation state of MDA and increased with decreasing pH of the soils. Because of the chemical reaction taking place, adsorption equilibrium constants (organic–carbon partition coefficient [K OC]) normalized to the organic carbon content in the soil gradually increased with time; and it was demonstrated that, at steady-state conditions, values of log K OC > 3.5 can be expected for most any soil at conservatively estimated potential environmental MDA concentrations. Environ Toxicol Chem 2023;00:1–9. © 2023 SETAC

Different Life‐Stage Exposure to Hexafluoropropylene Oxide Trimer Acid Induces Reproductive Toxicity in Adult Zebrafish (Danio rerio)

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Abstract

As a novel alternative to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide trimer acid (HFPO-TA) has been widely used and has caused ubiquitous water pollution. However, its adverse effects on aquatic organisms are still not well known. In the present study, zebrafish at different life stages were exposed to 0, 5, 50, and 100 μg/L of HFPO-TA for 21 days to investigate reproductive toxicity in zebrafish. The results showed that HFPO-TA exposure significantly inhibited growth and induced reproductive toxicity in zebrafish, including a decrease of the condition factor, gonadosomatic index, and the average number of eggs. Histological section observation revealed that percentages of mature oocytes and spermatozoa were reduced, while those of primary oocytes and spermatocytes increased. In addition, exposure to HFPO-TA at three stages induced a significant decrease in the hatching rate, while the heart rate and normal growth rate of F1 offspring were only significantly inhibited for the exposure from fertilization to 21 days postfertilization (dpf). Compared with the exposure from 42 to 63 dpf, the reproductive toxicity induced by HFPO-TA was more significant for the exposure from fertilization to 21 dpf and from 21 to 42 dpf. Expression of the genes for cytochrome P450 A1A, vitellogenin 1, estrogen receptor alpha, and estrogen receptor 2b was significantly up-regulated in most cases after exposure to HFPO-TA, suggesting that HFPO-TA exhibited an estrogen effect similar to PFOA. Therefore, HFPO-TA might disturb the balance of sex steroid hormones and consequently induce reproductive toxicity in zebrafish. Taken together, the results demonstrate that exposure to HFPO-TA at different life stages could induce reproductive toxicity in zebrafish. However, the underlying mechanisms deserve further investigation. Environ Toxicol Chem 2023;00:1–11. © 2023 SETAC

Influence of Particles on the Roller Discharge of Thin‐Film Filtration without Gas Throughput

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Influence of Particles on the Roller Discharge of Thin-Film Filtration without Gas Throughput

The impact of a particle system on the roller discharge is investigated comparing the behavior of the inorganic white pigment titanium dioxide and the biological model organism yeast. The quality of the removal properties of the filter cakes on a laboratory drum filter is recorded. Five different track-etched membranes are used to assess the filter properties with varying particle-pore size ratios.


Abstract

If fine and compressible particle systems need to be separated, the ground layer compaction caused by the compacting of the filter cake leads to high flow resistances. Thin-film filtration is a suitable method to avoid the limiting effect of the filter cakes. Gas-impermeable filter membranes prevent shrinkage cracking, which can occur during demoisturing of the filter cakes. Titanium dioxide and baker's yeast are used as model particle systems, which are present in different concentrations and are filtered with track-etched membranes in different particle-to-pore size ratios. The parameters determined during the investigation are the residual moisture, the specific solid mass, and the completeness of the discharge. Filtration causes progressive blocking of the membrane pores, resulting in filter medium resistances that are increased by up to a factor of 175. Metabolism of yeast can cause bubbles to accumulate on the membrane and decreasing the free filter area. Without regeneration the specific solid mass flow rate is reduced by 61 % for titanium dioxide and by 13 % for yeast under ideal conditions of this experimental study.