Palladium-mediated approach to dibenzo[b,e][1,4]diazepines and benzopyrido-analogues. An efficient synthesis of tarpane

An original synthetic route toward dibenzo[b,e][1,4]diazepin-11-ones and analogues pyridobenzodiazepinones has been developed. The method relies upon an intramolecular amination process between an (hetero)aryl halide and the appropriate aniline moiety.     

Two-dimensional mapping of three phenotype-associated isoforms of the prion protein in sporadic Creutzfeldt-Jakob disease

Transmissible spongiform encephalopathies (TSE), or prion diseases, are mammalian neurodegenerative disorders characterized by a conformational modification of the host-encoded prion protein (PrP(C)) into an isoform which is detergent-insoluble and partially resistant to protease treatment (PrP(Sc)). Distinct types of PrP(Sc), differing in conformation and variation in the relative amount of their glycoforms, have been associated with different phenotypes of TSE. In sporadic Creutzfeldt-Jakob disease (sCJD), two major types of PrP(Sc), with proteinase K (PK)-resistant fragments of 21 and 19 kDa, have been described. No consensus exists, however, on the molecular classification of PrP(Sc) in sCJD, since further heterogeneity within PrPSc conformers has been reported. We studied 19 subjects with dementia or dementia/ataxia at onset and 12 subjects with ataxia at onset. Following two-dimensional gel electrophoresis, we characterized PrP(C) and PrP(Sc) species in normal and sCJD brains by immunoblotting with antibodies recognizing N-terminal and C-terminal PrP regions. Three types of PrP(Sc) were detected in detergent-insoluble fractions from sCJD brains, mainly consisting of full-length PrP(Sc) in subjects with rapidly progressive dementia, and two different sets of amino-truncated PrP(Sc) glycoforms in subjects with dementia/ataxia and ataxia at onset. Examination of the PrP(Sc) core fragment, following PK treatment and deglycosylation, confirmed the existence of three distinctive patterns. These findings have immediate implications for the molecular classification of sCJD.     

Simultaneous detection and deconvolution of congested NMR spectra containing three isotopically labeled species

We present a procedure for isolating subspectra corresponding to individual protein or peptide components in a ternary mixture or complex. Each of the three-component species is labeled differently: species A uniformly with 15N, species B uniformly with 15N and 13C, and species C uniformly with 15N but selectively with 13C' or 13Calpha. By using the dual carbon label selective HSQC (DCLS-HSQC) pulse sequence and exploiting differences in 1J 15N-13C coupling patterns to filter selected 15N resonances from detection during a constant time period, a subspectrum from each species can be generated from three spectra acquired from a single sample. Many important biological pathways involve dynamic interactions among members of multicomponent protein assemblies, and this approach offers a powerful way to monitor such processes.     

Comparative Evaluation of the Nutrients,Phytochemicals, and Antioxidant Activity of Two Hempseed Oils and Their Byproducts after Cold Pressing

Recently, there has been a growing interest in the recovery of agri-food waste within the circular economy perspective. In this study, the nutritional, phytochemical, and biological features of the cold-pressed hempseed oil (HSO) and hempseed meal (HSM) of two industrial hemp varieties (USO 31 and Futura 75, THC ≤ 0.2%) were evaluated. The HSOs showed a high total phenols and flavonoid content, which were confirmed by LC-DAD-ESI-MS analysis, with rutin as the most abundant compound (56.93–77.89 µg/100 FW). They also proved to be a rich source of tocopherols (81.69–101.45 mg/100 g FW) and of a well-balanced ω-6 to ω-3 fatty acid ratio (3:1) with USO 31, which showed the best phytochemical profile and consequently the best antioxidant activity (about two times higher than Futura 75). The HSMs still retained part of the phytochemicals identified in the HSOs (polyphenols, tocopherols, and the preserved ω-6/ω-3 fatty acids ratio) and a modest antioxidant activity. Furthermore, they showed a very interesting nutritional profile, which was very rich in proteins (29.88–31.44 g/100 g FW), crude fibers (18.39–19.67 g/100 g), and essential and non-essential amino acids. Finally, only a restrained amount of anti-nutritional factors (trypsin inhibitors, phytic acid, and condensed tannins) was found, suggesting a promising re-use of these byproducts in the nutraceutical field.     

Dynamical and allosteric regulation of photoprotection in light harvesting complex Ⅱ

Major light-harvesting complex of photosystem Ⅱ(LHCⅡ) plays a dual role in light-harvesting and excited energy dissipation to protect photodamage from excess energy. The regulatory switch is induced by increased acidity, temperature or both. However,the molecular origin of the protein dynamics at the atomic level is still unknown. We carried out temperature-jump time-resolved infrared spectroscopy and molecular dynamics simulations to determine the energy quenching dynamics and conformational changes of LHCⅡ trimers. We found that the spontaneous formation of a pair of local α-helices from the 310-helix E/loop and the C-terminal coil of the neighboring monomer, in response to the increased environmental temperature and/or acidity, induces a scissoring motion of transmembrane helices A and B, shifting the conformational equilibrium to a more open state, with an increased angle between the associated carotenoids. The dynamical and allosteric conformation change leads to close contacts between carotenoid lutein 1 and chlorophyll pigment 612, facilitating the fluorescence quenching. Based on these results, we suggest a unified mechanism by which the LHCⅡ trimer controls the dissipation of excess excited energy in response to increased temperature and acidity, as an intrinsic result of intense sun light in plant photosynthesis.     

Aggregation Modes of Chiral Diketopyrrolo[3,4-c]pyrrole Dyes in Solution and Thin Films

The chiroptical features of chiral diketopyrrolo[3,4-c]pyrrole (DPP) derivatives have been only marginally investigated to date. In this regard, we have synthesized ad hoc four chiral DPP dyes, functionalized with enantiopure alkyl groups from natural sources either on the lactam moieties or on the terminal positions of the π-conjugated backbone, to promote an efficient self-assembly into chiral supramolecular structures. For each of them, the aggregation modes has been investigated by absorbance and ECD spectroscopies in conditions of solution aggregation and on thin films, considering the effects of deposition technique (drop casting vs. spin coating) and post-deposition operations (solvent and thermal annealing). The effect of the structure of lateral π-conjugated units attached to the central DPP scaffold, as well as that of the position of the alkyl chiral group, has been assessed. ECD revealed superior capability, compared to absorbance spectroscopy, to provide information on the aggregation modes and to detect the possible co-existence of multiple aggregation pathways.     

Chiral Oligothiophenes with Remarkable Circularly Polarized Luminescence and Electroluminescence in Thin Films

This work reports the first observation of circularly polarized electroluminescence (CPEL) in thin films of self-organized oligothiophenes. Four new 1,4-phenylene and 9H-carbazole-based oligothiophenes were ad hoc designed to ensure efficient spontaneous formation of chiral supramolecular order. They were easily synthesized and their chiroptical properties in thin films were measured. Circularly polarized luminescence (CPL) spectra revealed g_lum in the order of 10⁻² on a wide wavelengths range, originating from their self-organized chiral supramolecular organization. These molecules have reasonable properties as organic semiconductors and for this reason they can constitute the active layer of circularly-polarized organic light-emitting diodes (CP-OLEDs). Thus, we could investigate directly their electroluminescence (EL) and CPEL, without resorting to blends, but rather in a simple multilayer device with basic architecture. This is the first example of a CP-OLED with active layer made only of a small organic compound.     

Thermal analysis and high heat flux testing of unidirectional carbon–carbon composite for infrared imaging diagnostic

Carbothermic reduction of chromite in the presence of nickel as the alloying element was investigated in a wide temperature range up to 1500 °C using thermogravimetric analysis coupled with continuous off-gas analysis (TG-DSC-MS). Both isothermal and non-isothermal linear heating tests were performed for the kinetic study with the calculation of activation energies. In order to further elucidate the reduction mechanism, the reduced products were characterized by SEM–EDS and XRD. It was concluded that the reduction sequence followed a multi-stage mechanism, reflected partly by the dependency of the activation energy on the extent of reduction. With the progress of reduction, refractory oxide layers gradually formed on/close to the surface of each chromite particle, causing the shift of the rate-limiting factor from chemical control to diffusion control. The promoting effect from the addition of Ni was evident at temperatures higher than 1300 °C due to the formation of alloys of lower melting point.     

Fresnel tomography and interferometric technique for characterizing Laguerre–Gaussian beams

The Fresnel tomograms of Laguerre–Gaussian beams are found and the relation of the two-point spatial correlation function with the tomographic map is discussed. The spatial distribution and signature of vorticity of Laguerre–Gaussian modes is analyzed by measuring the two-point spatial correlation function of the one-dimensional projection of the vortex field. An interferometric approach, based on a Fourier projection algorithm, for the experimental determination of the two-point correlation function of the full complex vortex field at the cross-section plane of the recorded interference pattern is also described; this approach allows one to characterize the vortex structure and spatial coherence along the direction of propagation.