Search results for "two-dimensional"

The first sorbicillinoid alkaloids, the antileukemic sorbicillactones A and B, from a sponge-derived Penicillium chrysogenum strain

2005

The saltwater culture of a Penicillium chrysogenum strain isolated from the Mediterranean sponge Ircinia fasciculata yielded three new sorbicillin-derived compounds (1-3), whose structures were elucidated mainly by 2D NMR and mass spectrometry. Among them, sorbicillactones A (1) and B (2) are the first sorbicillinoid natural products that contain nitrogen. Compound 1 is anti-HIV active and it exhibits a strong cytotoxic activity against L5178y leukemic cells, combined with a relatively low toxicity to cervical carcinoma HeLa S3 cells and pheochromocytoma PC 12 cells. The absolute configurations of I and 2 were elucidated by quantum chemical calculation of circular dichroism (CD) spectra. An…

Two-Dimensional Indium Selenide for Sulphur Vapour Sensing Applications

2020

Surface-to-volume ratio in two-dimensional (2D) materials highlights among their characteristics as an inherent and intrinsic advantage taking into account their strong sensitivity to surface effects. For this reason, we have proposed in this work micromechanically exfoliated 2D nanosheets of InSe as an optical vapour sensor. As a proof of concept, we used 2-mercaptoethanol as the chemical analyte in vapour phase to monitor the change of the InSe photoluminescence (PL) before and after exposure to the analyte. For short vapour exposure times (at low analyte concentration), we found a PL enhancement of InSe nanosheets attributed to the surface localization of Se defects. For long vapour expo…

New pregnane and phenolic glycosides from Solenostemma argel.

2016

Abstract From the aerial parts, pericarps and roots of Solenostemma argel, three new pregnane glycosides (1–3) with two known ones and a new phenolic glycoside (4) have been isolated. Their structures were established by extensive 1D – and 2D NMR and mass spectroscopic analysis. The cytotoxicity of all compounds was evaluated against two human tumor cell lines (SW 480, MCF-7), but none of them was active in the concentration range 0.9–59.0 μM. Compounds 2 and the known argeloside F at non toxic concentrations for the PBMCs (27.3 μM and 27.6 μM, respectively) significantly decreased the Il-1β production by LPS-stimulated PBMCs. All isolated compounds showed a significant antioxidant potentia…

The apolipoprotein(a) moiety of lipoprotein(a) interacts with the complement activation fragment iC3b but does not functionally affect C3 activation …

1992

A previous study has shown that complement component C3 binds to recombinant apolipoprotein(a) (r-apo(a)). In the present report we have investigated the interactions between lipoprotein(a) (Lp(a)), r-apo(a) and C3 in relation to complement activation and degradation. Neither Lp(a) nor r-apo(a) affected complement activation as indicated by sheep and rabbit red blood cell hemolytic assays, and by assessment of the amount of C3a generated in zymosan-activated human serum in the presence or absence of Lp(a). Crossed immunoelectrophoretic analyses indicated that Lp(a) retarded the migration of iC3b in complement-activated serum but had no effects on C3, C3b, C3c or C3dg. Recombinant apo(a) exh…

Unusual oleanane-type saponins from Arenaria montana

2010

Three oleanane-type saponins, 3-O-β-d-glucopyranosylechinocystic acid 28-O-β-d-xylopyranosyl-(1→4)-[α-l-rhamnopyranosyl-(1→2)]-α-l-rhamnopyranosyl ester (1), 3-O-β-d-glucopyranosylechinocystic acid 28-O-α-l-arabinopyranosyl-(1→3)-β-d-xylopyranosyl-(1→4)-[α-l-rhamnopyranosyl-(1→2)]-α-l-rhamnopyranosyl ester (2), 3-O-β-d-glucopyranosylcaulophyllogenin 28-O-β-d-apiofuranosyl-(1→3)-β-d-xylopyranosyl-(1→4)-[β-d-apiofuranosyl-(1→3)]-α-l-rhamnopyranosyl-(1→2)-α-l-rhamnopyranosyl ester (3) were isolated from the whole plant of Arenaria montana. Their unusual structures for the Caryophyllaceae family were established mainly by 2D NMR techniques and mass spectrometry.

New organotin(IV) complexes with L-Arginine,Nα-t-Boc-L-Arginine and L-Alanyl-L-Arginine.Synthesis, structural investigations and cytotoxic activity

2010

Abstract Novel diorganotin(IV) derivatives of l -Arginine (HArg), N α -( tert -Butoxycarbonyl)- l -Arginine (Boc–Arg–OH) and l -Ala- l -Arg (H 2 Ala–Arg), H 2 NC( NH)NH(CH 2 ) 3 CH(NHR′)CO 2 H, where R′ = H in HArg, R′ = C(O)OC(CH 3 ) 3 in Boc–Arg–OH, R′ = H 2 NCH(CH 3 )CO in H 2 Ala–Arg and triorganotin(IV) derivatives of Boc–Arg–OH have been synthesized and structurally characterized. The complexes were investigated by FT-IR and 119 Sn Mossbauer in the solid state and by 1 H, 13 C, 119 Sn and 1 H– 1 H COSY NMR spectroscopy, in solution. The spectroscopic characterization leading to the proposed molecular structures was accomplished on the basis of these experiments. l -Arginine appears to…

The Monotone Area-preserving Flux-Form Advection Algorithm: Reducing the Time-splitting Error in Two-Dimensional Flow Fields

1993

Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance

2015

Zero- to ultra-low-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero- to ultra-low-field NMR measurements of residual dipolar couplings in acetonitrile…

Cytotoxic labdane diterpenes and bisflavonoid atropisomers from leaves of Araucaria bidwillii

2017

Abstract Chemical investigation of a methanolic extract of leaves from Araucaria bidwillii (Araucariaceae) from Egypt afforded four new labdane diterpenoidal metabolites (1–4) together with one known diterpene, 7-oxocallitrisic acid (5), two triterpenoidal metabolites, 2-O-acetyl-11-keto-boswellic acid (6) and β-sitosterol-3-O-glucopyranoside (7), phloretic acid (8), and two methylated bisflavonoids, agathisflavone-4′,7,7″-trimethyl ether (9) and cupressuflavone-4′,7,7″-trimethyl ether (10). The new metabolites 1–4 were unambiguously identified by applying extensive 1D and 2D NMR spectroscopic studies as well as HRESIMS. The relative and absolute configurations of 1–4 were determined using …

New upper bounds for some instances from benchmark for vector packing problem

2021

This dataset is a result of the research: Đorđe Stakić, Miodrag Živković, Ana Anokić, "A Reduced Variable Neighborhood Search Approach to the Heterogeneous Vector Bin Packing Problem", Information Technology and Control, 2021, 50(4), 808-826, https://doi.org/10.5755/j01.itc.50.4.29009 Files are given by algorithm described in it. This dataset consists of 14 solutions with better bounds for instances described in paper: Heßler, K., Gschwind, T., Irnich, S. Stabilized branch-and-price algorithms for vector packing problems. European Journal of Operational Research, 2018, 271(2), 401-419. https://doi.org/10.1016/j.ejor.2018.04.047 File structure: Instance name: UB: solut…