Generalist versus Specialist Self-Replicators.

Darwinian evolution, including the selection of the fittest species under given environmental conditions, is a major milestone in the development of synthetic living systems. In this regard, generalist or specialist behavior (the ability to replicate in a broader or narrower, more specific food environment) are of importance. Here we demonstrate generalist and specialist behavior in dynamic combinatorial libraries composed of a peptide-based and an oligo(ethylene glycol) based building block. Three different sets of macrocyclic replicators could be distinguished based on their supramolecular organization: two prepared from a single building block as well as one prepared from an equimolar mixture of them. Peptide-containing hexamer replicators were found to be generalists, i. e. they could replicate in a broad range of food niches, whereas the octamer peptide-based replicator and hexameric ethyleneoxide-based replicator were proven to be specialists, i. e. they only replicate in very specific food niches that correspond to their composition. However, sequence specificity cannot be demonstrated for either of the generalist replicators. The generalist versus specialist nature of these replicators was linked to their supramolecular organization. Assembly modes that accommodate structurally different building blocks lead to generalist replicators, while assembly modes that are more restrictive yield specialist replicators.

New tobacco products, old advertising strategies: point-of-sale advertising in Guatemala.

OBJECTIVE: Capsule cigarettes, electronic cigarettes (e-cigarettes) and heated tobacco products (HTPs) are now readily available in Guatemala. As in most countries, the point-of-sale (POS) remains an important marketing channel for the tobacco industry. Therefore, we sought to characterise the POS marketing of these products in the two largest cities in Guatemala. METHODS: Convenience stores were randomly surveyed in mid and high socioeconomic status (SES) neighbourhoods in Guatemala City (n=60) and Quetzaltenango (n=15) in 2019. We adapted a previously implemented checklist to assess the availability of interior advertising of capsule cigarettes, e-cigarettes and HTP. Data entry was done in Kobo toolbox and analysis in STATA. RESULTS: All stores sold conventional and flavoured capsule cigarettes, 78% e-cigarettes and 68% HTP. Most cigarette advertising was for capsule cigarettes. E-cigarettes were more likely to be sold in Guatemala City (96%) than in Quetzaltenango (13%). HTPs were only found in Guatemala City (85%), with no difference between high and medium SES neighbourhoods. Median number of ads for cigarettes and capsule cigarettes was higher in the high SES neighbourhood. Most e-cigarettes (83%) and HTP (74%) were found <50 cm from candy. E-cigarettes and HTP were available in a wide range of flavours. All stores that sold HTP had flavoured HEETS (amber, bronze, turquoise, yellow, blue and purple). CONCLUSION: We found a high prevalence of advertising for capsule cigarettes, e-cigarettes and HTP at the POS. The POS, a crucial advertising channel for the tobacco industry, is now being used for new products and therefore needs to be urgently regulated.

Intramolecular Nicholas Reaction Enables the Stereoselective Synthesis of Strained Cyclooctynes.

Cyclic products can be obtained through the intramolecular version of the Nicholas reaction, which requires having the nucleophile connected to the alkyne unit. Here, we report the synthesis of 1-oxa-3-cyclooctynes starting from commercially available (1R,3S)-camphoric acid. The strategy is based on the initial preparation of propargylic alcohols, complexation of the triple bond with Co2(CO)8, and treatment with BF3·Et2O to induce an intramolecular Nicholas reaction with the free hydroxyl group as nucleophile. Finally, oxidative deprotection of the alkyne afforded the cyclooctynes in good yields. Notably, large-sized R substituents at the chiral center connected to the O atom were oriented in such a way that steric interactions were minimized in the cyclization, allowing the formation of cyclooctynes exclusively with (R) configuration, in good agreement with theoretical predictions. Moreover, preliminary studies demonstrated that these cyclooctynes were reactive in the presence of azides yielding substituted triazoles.

Characteristics of illegal and legal cigarette packs sold in Guatemala.

BACKGROUND: Guatemala, as a party to the Framework Convention on Tobacco Control (FCTC), is required to regulate cigarette packaging and labeling and eliminate illicit tobacco trade. Current packaging and labeling characteristics (of legal and illegal cigarettes) and their compliance with the FCTC is unknown. METHODS: We sought to analyze package and label characteristics of illegal and legal cigarettes sold in Guatemala. We visited the 22 largest traditional markets in the country to purchase illegal cigarettes. All brands registered on tobacco industry websites were purchased as legal cigarettes. Analysis compared labeling characteristics of illegal and legal packs. FINDINGS: Most (95%) markets and street vendors sold illegal cigarettes; 104 packs were purchased (79 illegal and 25 legal). Ten percent of illegal and none of the legal packs had misleading terms. Half of the illegal packs had a warning label covering 26 to 50% of the pack surface. All legal packs had a label covering 25% of the surface. Illegal packs were more likely to have information on constituents and emissions (85% vs. 45%, p < 0.001) and were less expensive than legal ones (USD 0.70 ± 0.7 and 1.9 ± 1.8, p < 0.001). CONCLUSIONS: In Guatemala, neither illegal nor legal cigarette packs comply with FCTC labeling mandates. Urgent implementation and enforcement of the FCTC is necessary to halt the tobacco epidemic.

Block Copolymer-Based Membranes for Vanadium Redox Flow Batteries: Synthesis, Characterization, and Performance.

Nonfluorinated polymers have been widely proposed to replace Nafion as raw materials for redox flow battery ion-exchange membranes. Hereby, block copolymers based on polysulfone (PSU) and polyphenylsulfone (PPSU) are synthesized and employed as precursors of membranes for vanadium redox flow batteries. A series of copolymers with varying molar proportions of PSU (75/25, 60/40, 50/50 mol %) were prepared. The 60/40 and 75/25 copolymers exhibit concentrated sulfonic groups predominantly in the PSU unit, favoring the formation of hydrophobic and hydrophilic domains. The 50/50 copolymer presents a balanced degree of sulfonation between the two units, leading to a homogeneous distribution of sulfonic groups. An ex situ study of these materials comprising vanadium ion permeability and chemical and mechanical stability was performed. The best performance is achieved with 50/50 membranes, which exhibited performance comparable to commercial Nafion membranes. These results signify a promising breakthrough in the pursuit of high-performance, sustainable membranes for next-generation VRFBs.

Mild-Base-Promoted Arylation of (Hetero)Arenes with Anilines.

Transition metal-free radical arylation of heteroarenes is achieved at room temperature by simply adding aqueous sodium carbonate to a solution of the corresponding heteroarene and arenediazonium salt, which can even be formed in situ. Such an easy, inexpensive and mild methodology has been optimized and applied to the expeditious modification of interesting molecular cores like naphthylimide or bisthienylcyclopentenes.

Radical C-H arylations of (hetero)arenes catalysed by gallic acid.

Gallic acid efficiently catalyses radical arylations in water-acetone at room temperature. This methodology proved to be versatile and scalable. Therefore, it constitutes a greener alternative to arylation. Moreover, considering that gallic acid is an abundant vegetable tannin, this work also unleashes an alternative method for the reutilisation of bio-wastes.

Oxidation with air by ascorbate-driven quinone redox cycling.

Transition metal-free oxidation with air at room temperature has been achieved by simply using ascorbate (vitamin C) and catalytic amounts of menadione (vitamin K3). A combination of the mentioned vitamins transforms atmospheric oxygen into hydrogen peroxide, which is able to oxidize arylboronic acids and other chemical moieties.

Cirugía de raíz aórtica tras switch arterial / Aortic root surgery after arterial switch operation

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