Easy access to 3,8-Diaryldifurano[2,3-a:2',3'-f]naphthalenes. A new extended aromatic system

3,8-Diaryldifurano[2,3-a:2',3'-f]naphthalenes were prepared in two simple steps. First, 1,5-dihydroxynaphthalene and 1-aryl-2-bromodecan-1-ones were condensed to the corresponding naphthalene 1,5-diethers. Second, these intermediates were cyclized using methanesulfonic acid in methylene chloride. Seven examples are given, three of which are doubly substituted with octyl chains to enhance the solubility. This increased solubility allowed further modification of the 3,8-aryl groups to attach electron-withdrawing groups (formyl, nitrile, dicyanovinyl, and benzoyl).     

Macrocyclization of alpha-(alkynyloxy)silyl-alpha-diazoacetates by inter-/intramolecular

Thermally induced intra-/intermolecular [3 + 2] cycloaddition reaction sequences of alpha-(alkynyloxy)silyl-alpha-diazoacetates 1 lead to [3.3](1,4)pyrazolophanes (2)2 and higher cyclooligomers thereof [(2)n, n > 2]. In most cases, the cyclodimer was isolated by crystallization, while a complete separation of the mixture of the higher cyclooligomers was not possible. Solid state structures of cyclodimers (2b)2 and (2c)2, cyclotrimer (2b)3, and cyclotetramer (2e)4 were determined by X-ray diffraction analysis. Field-desorption mass spectra were used to characterize the cyclooligomer mixtures. The relative amounts of the cyclooligomers depend on the substitution pattern of the diazo compound. The cyclooligomerization reactions reported herein demonstrate, for the first time, the involvement of diazo functions in macrocyclization reactions via 1,3-dipolar cycloaddition.     

Steric and conformational control of the regioselectivities in the ene reaction with trisubstituted cycloalkenes: comparison of the enophiles singlet oxygen, triazolinedione, and nitrosoarene

The nitrosoarene ene reaction with the cycloalkenes 1-3 and E-4 proceeds in high twix regioselectivity to afford the hydroxylamine ene products 1a-4a (twix) and 1b-4b (twin, except far E-4 twix). Steric interactions in the enophile attack are responsible for the skew trajectory of the nitrosoarene enophile. For Z-1-methylcyclooctene (Z-4), twin abstraction dominates, caused by conformational constraints (transannular interactions) in the hydrgogen-atom abstraction. The balance between these steric and conformational factors dictates the regioselectivity in the ene reaction     

Lattice simulations for light nuclei: Chiral effective field theory at leading order

We discuss lattice simulations of light nuclei at leading order in the chiral effective field theory. Using lattice pion fields and auxiliary fields, we include the physics of instantaneous one-pion exchange and the leading-order S-wave contact interactions. We also consider higher-derivative contact interactions which adjust the S-wave scattering amplitude at higher momenta. By construction our lattice path integral is positive definite in the limit of exact Wigner SU(4) symmetry for any even number of nucleons. This SU(4) positivity and the approximate SU(4) symmetry of the low-energy interactions play an important role in suppressing sign and phase oscillations in Monte Carlo simulations. We assess the computational scaling of the lattice algorithm for light nuclei with up to eight nucleons and analyze in detail calculations of the deuteron, triton, and helium-4.     

Large eddy simulation of piloting effects on turbulent swirling flames

Pilot flames, created by additional injectors of pure fuel, are often used in turbulent burners to enhance flame stabilization and reduce combustion instabilities. The exact mechanisms through which these additional rich zones modify the flame anchoring location and the combustion dynamics are often difficult to identify, especially when they include unsteady hydrodynamic motion. This study presents Large Eddy Simulations (LES) of the reacting flow within a large-scale gas turbine burner for two different cases of piloting, where either 2 or 6% of the total methane used in the burner is injected through additional pilot flame lines. For each case, LES shows how the pilot fuel injection affects both flame stabilization and flame stability. The 6% case leads to a stable flame and limited hydrodynamic perturbations in the initial flame zone. The 2% case is less stable, with a small-lift-off of the flame and a Precessing Vortex Core (PVC) in the cold stabilization zone. This PVC traps some of the lean cold gases issuing from the pilot passage stream, changes the flame stabilization point and induces instability.     

Considering baseline homophily when generating spatial social networks for agent-based modelling

Social networks have become an important part of agent-based models, and their structure may have remarkable impact on simulation results. We propose a simple and efficient but empirically based approach for spatial agent-based models which explicitly takes into account restrictions and opportunities imposed by effects of baseline homophily, i.e. the influence of local socio-demography on the composition of one’s social network. Furthermore, the algorithm considers the probability of links that depends on geographical distance between potential partners. The resulting network reflects social settings and furthermore allows the modeller to influence network properties by adjusting agent type specific parameters. Especially the parameter for distance dependence and the probability of distant links allow for control of clustering and agent type distribution of personal networks.     

Magnetic moment of proton halo nucleus 28 P

The magnetic moment of ²⁸P (I _π = 3^?+?, T_1/2 = 270.3 ms) in the ground state has been measured by the $\upbeta $ -nuclear magnetic resonance method for the first time. The measured magnetic moment of $\vert \upmu (^{28}$ P)∣ = 0.309(9)  $\upmu _{{\rm N}}$ is well reproduced by the shell model value of +0.306  $\upmu _{{\rm N} }$ . The shell model calculation also yields a proton density distribution with a long tail. The present results provide a strong confirmation of the configuration of the 2s _1/2 proton which should lead to the proton halo.     

Isoelectric point determination by imaged CIEF of commercially available SARS-CoV-2 proteins and the hACE2 receptor

In order to contribute to the scientific research on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we have investigated the isoelectric points (pI) of several related proteins, which are commercially available: the receptor-binding domain (RBD) with His- and Fc-tag, the S1 subunit with His-tag, the S1/S2 subunits with His-tag and the human angiotensin-converting enzyme 2 (hACE2) with His-tag. First, the theoretical pI values, based on the amino acid (AA) sequences of the proteins, were calculated using the ProtParam tool from the Bioinformatics Resource Portal ExPASy. The proteins were then measured with the Maurice imaged CIEF system (native fluorescence detection), testing various measurement conditions, such as different ampholytes or ampholyte mixtures. Due to isoforms, we get sections with several peaks and not just one peak for each protein. The determined pI range for the RBD/Fc is 8.24–9.32 (theoretical pI: 8.55), for the RBD/His it is 7.36–9.88 (8.91) and for the S1/His it is 7.30–8.37 (7.80). The pI range of the S1/S2/His is 4.41–5.87 (no theoretical pI, AA sequence unknown) and for hACE2/His, the determined global range is 5.19–6.11 (5.60) for all experimental conditions chosen. All theoretically derived values were found within these ranges, usually close to the center. Therefore, we consider theoretical values as useful to make predictions about the isoelectric points of SARS-CoV-2 proteins. The experimental conditions had only a minor influence on the pI ranges obtained and mainly influenced the peak shapes.     

A comparative study of CE-SDS,SDS-PAGE,and Simple Western—Precision,repeatability, and apparent molecular mass shifts by glycosylation

SDS gel electrophoresis is a commonly used approach for monitoring purity and apparent molecular mass (Mr) of proteins, especially in the field of quality control of biopharmaceutical proteins. The technological installation of CE-SDS as the replacement of the slab gel technique (SDS-PAGE) is still in progress, leading to a continuous improvement of CE-SDS instruments. Various CE-SDS instruments, namely Maurice (CE-SDS/CE-SDS PLUS) and Wes by ProteinSimple as well as the microchip gel electrophoresis system LabChip® GXII Touch™ HT by PerkinElmer were tested for precision and repeatability compared to SDS-PAGE (Bio-Rad). For assessing these quality control parameters, standard model proteins with minor post-translational modifications were used. Overall, it can be concluded that the CE-SDS-based methods are similar to SDS-PAGE with respect to these parameters. Quality characteristics of test systems gain more significance by testing proteins that do not behave like model proteins. Therefore, glycosylated proteins were analyzed to comparatively investigate the influence of glycosylation on Mr determination in the different instruments. In some cases, high deviations were found both among the methods and with regard to reference values. This article provides possible explanations for these findings.