Metal-Free Reversible Double Cyclization of Cyanuric Diazide to an Asymmetric Bitetrazolate via Cleavage of the Six-Membered Aromatic Ring.

Crystallization of the reaction mixture of 2-amino-4,6-diazido-1,3,5-triazine and excess tert-butylamine results in the isolation of tert-butylammonium N,N-[1'H-(1,5'-bitetrazol)-5-yl]cyanamidate, suggesting a complex decyclization/cyclization rearrangement involving breakage of the six-membered aromatic ring and the formation of two new five-membered azole rings mediated by deprotonation of the precursor by the amine. The addition of tert-butylamine to 2-amino-4,6-diazido-1,3,5-triazine gives spectroscopic indication of thermodynamically unfavorable reactivity in low-dielectric solvents, and high-level quantum chemical computations also suggest its formation to be unfavorable. A computed interconversion pathway describes the likely reaction mechanism and supports the general thermodynamic unfavorability of the reaction and the requirement for a high-dielectric environment to template formation of the ionic product and its trapping by crystallization.

Emergence and spread of novel H5N8, H5N5 and H5N1 clade 2.3.4.4 highly pathogenic avian influenza in 2020.

Analyses of HPAI H5 viruses from poultry outbreaks across a wide Eurasian region since July 2020 including the Russian Federation, Republics of Iraq and Kazakhstan, and recent detections in migratory waterfowl in the Netherlands, revealed undetected maintenance of H5N8, likely in galliform poultry since 2017/18 and both H5N5 and H5N1. All viruses belong to A/H5 clade 2.3.4.4b with closely related HA genes. Heterogeneity in Eurasian H5Nx HPAI emerging variants threatens poultry production, food security and veterinary public health.

Transition-metal-mediated reduction and reversible double-cyclization of cyanuric triazide to an asymmetric bitetrazolate involving cleavage of the six-membered aromatic ring.

Cyanuric triazide reacts with several transition metal precursors, extruding one equivalent of N2 and reducing the putative diazidotriazeneylnitrene species by two electrons, which rearranges to N-(1'H-[1,5'-bitetrazol]-5-yl)methanediiminate (biTzI2-) dianionic ligand, which ligates the metal and dimerizes, and is isolated from pyridine as [M(biTzI)]2Py6 (M = Mn, Fe, Zn, Cu, Ni). Reagent scope, product analysis, and quantum chemical calculations were combined to elucidate the mechanism of formation as a two-electron reduction preceding ligand rearrangement.

Randomised trial of the comparison of drug-eluting stents in patients with diabetes: OCT DES trial.

Background: To date, there have been limited comparisons performed between everolimus-eluting stents (EES) and zotarolimus-eluting stents (ZES) in patients with diabetes mellitus (DM). The objectives of this study was to assess the use of second-generation drug-eluting stents in patients with DM, using optical coherence tomography (OCT) to compare the level of stent coverage of Boston Scientific Promus Element EES compared with Medtronic Resolute Integrity ZES.(Clinicaltrials.gov number NCT02060357). Methods: This is a single-centre randomised blinded trials assessing two commercially available stents in 60 patients with diabetes (ZES: n=30, EES: n=30). Patients underwent intracoronary assessment at 6 months with OCT assessing stent coverage, malapposition, neointimal thickness and percentage of in-stent restenosis (ISR). Results: Of the 60 patients randomised, 46 patients underwent OCT analysis. There was no difference in baseline characteristics between the two groups. Both Promus Element and Resolute Integrity had low rates of uncovered struts at 6 months with no significant difference between the two groups (2.44% vs 1.24%, respectively; P=0.17). Rates of malapposition struts (3.9% vs 2.5%, P=0.25) and percentage of luminal loss did not differ between stent types. In addition, there was no significant difference in major adverse cardiovascular events (P=0.24) between the stent types. Conclusions: This study is the first randomised trial to evaluate OCT at 6 months for ZES and EES in patients with diabetes. Both stents showed comparable strut coverage at 6 months, with no difference in ISR rates at 6 months.

An observational study of clinical outcomes of everolimus-eluting bioresorbable scaffolds comparing the procedural use of optical coherence tomography against angiography alone.

OBJECTIVES: The introduction of the bioresorbable vascular scaffold (BVS) has led to new avenues of coronary intervention; however, there have been concerns raised regarding the mechanical properties of BVS and the resulting in-stent thrombosis. We aim to assess whether intracoronary imaging improves outcome in patients following BVS implantation. PATIENTS AND METHODS: All patients undergoing percutaneous coronary intervention using BVS at a single centre between June 2013 and June 2016 were included in this study (n=79). Percutaneous coronary intervention with BVS was performed according to conventional practice: predilatation, postdilatation and intracoronary assessment with optical coherence tomography (OCT) according to operator's preferences. The primary endpoint was Major Adverse Cardiovascular Events (MACE), defined as all-cause mortality, myocardial infarction and revascularization, at 120 days. RESULTS: Forty-three (54.4%) patients underwent OCT assessment and 36 (45.6%) patients underwent angiography alone post-BVS insertion. There were no significant differences at baseline between both groups; a total of 13 (30.2%) patients who had intracoronary OCT imaging performed underwent further postdilatation after malapposed struts were identified. Although no deaths were observed, there was a significant difference seen in MACE over the follow-up period between OCT and angiography cohorts (4.7 vs. 19.4% respectively; P=0.042). There was a greater number of MACE in low-experienced operators. CONCLUSION: As visual assessment with angiography has poor specificity for identifying strut malapposition, intracoronary OCT should be undertaken in all patients postinsertion of BVS stents in inexperienced operators to appropriately assess for stent malapposition, and reduce the subsequent risk of MACE.

Color Relationalism and Relativism.

This paper critically examines color relationalism and color relativism, two theories of color that are allegedly supported by variation in normal human color vision. We mostly discuss color relationalism, defended at length in Jonathan Cohen's The Red and the Real, and argue that the theory has insuperable problems.

Color realism and color science.

The target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically, types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in the mind." The article has two other purposes: First, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. The first part explains the problem of color realism and makes some useful distinctions. These distinctions are then used to expose various confusions that often prevent people from seeing that the issues are genuine and difficult, and that the problem of color realism ought to be of interest to anyone working in the field of color science. The second part explains the various leading answers to the problem of color realism, and (briefly) argues that all views other than our own have serious difficulties or are unmotivated. The third part explains and motivates our own view, that colors are types of reflectances and defends it against objections made in the recent literature that are often taken as fatal.

Challenges of short magnet design.

The desire to improve patient comfort and acceptance of high field magnetic resonance imaging (MRI) systems results in new approaches to magnet and other critical MRI component design. One such approach, based upon an anatomical field of view analysis, is presented in this paper. The approach is utilized to define imaging volume requirements for short, high field, solenoid magnet designs that maintain whole body imaging capability. A short magnet design with excellent magnetic field homogeneity is presented accordingly. Combined with a novel flared gradient coil the overall system achieves improvements in openness.