{\gamma}-Fe phase plasma-induced on the surface of thin S3A alloy ribbons

Amorphous alloy ribbons of Fe₇₇Cr₂B₁₆Si₅ were exposed to cold plasmas of N₂ and Ar?CN₂ at temperatures lower than T_x?=?808?K. The conversion X-ray M?ssbauer spectra of the plasma-exposed ribbons consist of a singlet and a broadened magnetic sextet. The singlet with isomer shift $\updelta = -0.11$ ?mm/s can be assigned to $\upgamma $ -Fe austenite phase. Minor bulk magnetic changes in the alloy were measured as a consequence of these treatments; e.g. the relative intensities A23 of the transmission M?ssbauer spectra of the untreated and treated samples, were 3.22 and 3.56, respectively, the B_hf values changed from 22.9?T (untreated sample) to 22.4?T (plasma treated samples). Unexpectedly, the $\upgamma $ -Fe phase can also be produced by simply heating the alloy ribbons under N₂ flux at temperatures as low as 423?K. M?ssbauer data of the crystallized samples are also reported, and a qualitative assessment on the mechanical properties of the Fe₇₇Cr₂B₁₆Si₅ alloy associated with the plasma and/or temperature surface induced $\upgamma $ -Fe phase is given.     

Study of Chlorambucil and Chlorambucil–Trimethyl-β-cyclodextrin Inclusion Complex by CE

The results of CE studies of solid inclusion complexes of chlorambucil (CHL) and trimethyl-β-cyclodextrin (TM-β-CD) are presented. Chlorambucil has low stability in aqueous solution, so the formation of complexes with β-CD is a good way to improve its stability and dissolution. The experimental results confirm the existence of inclusion complexes. CE can differentiate free CHL from CHL–TM-β-CD complexes due to their different electrophoretic mobilities.     

Assembling OX40 aptamers on a molecular scaffold to create a receptor-activating aptamer

We show that a molecular scaffold can be utilized to convert a receptor binding aptamer into a receptor agonist. Many receptors (including tumor necrosis receptor family members) are activated when they are multimerized on the cell surface. Molecular scaffolds have been utilized to assemble multiple receptor binding peptide ligands to generate activators of such receptors. We demonstrate that an RNA aptamer that recognizes OX40, a member of the tumor necrosis factor receptor superfamily, can be converted into a receptor-activating aptamer by assembling two copies on an olignucleotide-based scaffold. The OX40 receptor-activating aptamer is able to induce nuclear localization of nuclear factor-kappaB, cytokine production, and cell proliferation, as well as enhance the potency of dendritic cell-based tumor vaccines when systemically delivered to mice.     

1H-Azepine-4-amino-4-carboxylic acid: a new α,α-disubstituted ornithine analogue capable of inducing helix conformations in short Ala-Aib pentapeptides

A very efficient synthesis of orthogonally protected 1H-azepine-4-amino-4-carboxylic acid, abbreviated as Azn, a conformationally restricted analogue of ornithine, was realized. It was obtained on a gram scale in good overall yield in five steps, three of which did not require isolation of the intermediates, starting from the readily available 1-amino-4-oxo-cyclohexane-4-carboxylic acid. Both enantiomers were used for the preparation of pentapeptide models containing Ala, Aib, and Azn. Conformational studies using both spectroscopic techniques (NMR, CD) and molecular dynamics on model 5-mer peptides showed that the (R)-Azn isomer possesses a marked helicogenic effect.     

TiCl4/t-BuNH2-promoted hydroamination/annulation of delta-keto-acetylenes: synthesis of novel pyrrolo[1,2-a]indol-2-carbaldehydes

[reaction: see text] An original TiCl(4)/t-BuNH(2)-mediated hydroamination/annulation domino reaction of delta-keto-acetylenes is described. The synthesis of pyrrolo[1,2-a]indole-2-carbaldehydes, starting from 2-carbonyl-1-propargyl-1H-indoles runs under mild reaction conditions. A conceivable mechanism is also discussed. TiCl(4) has proved to be an effective multiactivity reagent: catalyst/Lewis acid/water scavenger. Some unpublished 2-carbonyl-1-propargyl-1H-indoles are prepared by means of Suzuki- and Negishi-type reactions.     

Carbon Quantum Dot Optical Properties for potential infiltration into Hollow Core Photonic Crystal Fibers

Carbon quantum dots (CQD) have received significant attention in recent years due to their potential applications in optics and sensing. In this study, the authors report on the first characterization of the optical activity and broad absorption spectrum covering from short-wave ultraviolet, at 200 nm, to mid-infrared, at 1600 nm, of CQD synthesized using the “low-molecular-weight alcohols electrochemical carbonization” method. The CQD are analyzed using spectroscopic techniques, optical activity in the infrared, and high-resolution transmission electron microscopy. Results show a CQD size distribution of 5±3 nm and spherical morphology. The absorption spectra show increased absorption at both, high and low frequency. Additionally, the specific rotation of the CQD solution is significantly higher than that of pure ethanol, by three orders of magnitude. These findings suggest that CQD may have potential applications in polarized infrared filters and/or sensors due to their ability to rotate the polarization state of light at 1550 nm. The results of this study provide valuable insights into the optical properties of CQD and their potential for infiltration into hollow core photonic crystal fibers, making them a promising material for future research and development in the field of optics and sensing.     

ChemInform Abstract: Theoretical Investigation of Clusters of Phosphorus and Arsenic: Fascination and Temptation of High Symmetries.

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