Shear-strain-induced Spatially Varying Super-lattice Structures on Graphite studied by STM

We report on the Scanning Tunneling Microscope (STM) observation of linear fringes together with spatially varying super-lattice structures on (0001) graphite (HOPG) surface. The structure, present in a region of a layer bounded by two straight carbon fibers, varies from a hexagonal lattice of 6nm periodicity to nearly a square lattice of 13nm periodicity. It then changes into a one-dimensional (1-D) fringe-like pattern before relaxing into a pattern-free region. We attribute this surface structure to a shear strain giving rise to a spatially varying rotation of the affected graphite layer relative to the bulk substrate. We propose a simple method to understand these moire patterns by looking at the fixed and rotated lattices in the Fourier transformed k-space. Using this approach we can reproduce the spatially varying 2-D lattice as well as the 1-D fringes by simulation. The 1-D fringes are found to result from a particular spatial dependence of the rotation angle.Comment: 14 pages, 6 figure

On Color Critical Graphs of Star Coloring

A \emph{star coloring} of a graph $G$ is a proper vertex-coloring such that no path on four vertices is $2$-colored. The minimum number of colors required to obtain a star coloring of a graph $G$ is called star chromatic number and it is denoted by $\chi_s(G)$. A graph $G$ is called $k$-critical if $\chi_s(G)=k$ and $\chi_s(G -e) < \chi_s(G)$ for every edge $e \in E(G)$. In this paper, we give a characterization of 3-critical, $(n-1)$-critical and $(n-2)$-critical graphs with respect to star coloring, where $n$ denotes the number of vertices of $G$. We also give upper and lower bounds on the minimum number of edges in $(n-1)$-critical and $(n-2)$-critical graphs

21-Hy­droxy­pregna-1,4-diene-3,20-dione

The title compound, C21H28O3, is a fungal transformed metabolite of decoxycorticosterone acetate, consisting of four fused rings A, B, C and D. Ring A is nearly planar, with a maximum deviation of 0.010 (3) Å from the least-squares plane, while the trans-fused rings B and C adopt chair conformations. The five-membered ring D is in an envelope conformation. The orientation of the side chain is stabilized by an intramolecular O—H⋯O hydrogen bond. In the crystal, adjecent mol­ecules are linked by C—H⋯O hydrogen bonds into extended zigzag chains along the a axis

Chemical constituents of Eremomastax speciosa (Hochst.) Cufod leaves and its cytotoxic potential on NIH-3T3 cells

This study aimed at assessing the cytotoxicity of Eremomastax speciosa crude extract on NIH-3T3 fibroblast cell lines and reporting the chemical constituents in the extract. The MTT assay on NIH-3T3 cells showed a significantly lower (p &lt; 0.05) inhibition from E. speciosa (IC50 &gt; 30 µg/mL) compared to cyclohexamide (IC50 &gt; 0.8 µg/mL). This result validates the non-toxicity observed with the use of E. speciosa on normal cells at low to moderate doses. Four compounds were isolated and identified from their EIMS as well as 1D and 2D NMR spectroscopic data namely hydroxyandrographolide (1), stigmasterol glucoside (2), (Z)-4-coumaric acid 4-O-β-D-apiofuranosyl-(1’’→2’)-O-β-D-glucopyranoside (3) and 5-methoxy-4,4′-di-O-methyl- secolariciresinol-9′-monoacetate (4). These compounds are isolated from this species for the first time. Thirteen volatile constituents were detected in the extract using gas chromatography mass spectrometry (GC-MS). Besides 6,10,14-trimethy-2-pentadecanone (12.63%), mostly fatty acid esters were detected in high amounts notably ethyl hexadecanoate (16.00%), ethyl-9,12,15-octadecatrienoate (11.51%) and 9,12-octadecadienoic acid ethyl ester (8.05%). This study revealed many unsaturated fatty acid esters in E. speciosa and is noteworthy that ω-3 and ω-6 fatty acid esters were predominant, hence an added nutritional value to this plant. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; KEY WORDS: Eremomastax speciosa, Secondary metabolites, NIH-3T3 cytotoxicity, NMR, GC-MS &nbsp; Bull. Chem. Soc. Ethiop. 2020, 34(3), 633-640. DOI: https://dx.doi.org/10.4314/bcse.v34i3.1

Case report of serial pleural effusion managed with good fetal outcome

Fetal pleural effusion is a rare congenital anomaly that occurs when some amount of fluid surrounds the fetal lung without concomitant hydrops. It may remain the same or progress more. We present here a case of a 32-year-old lady with primary infertility who conceived naturally. She presented to us for her routine term pregnancy evaluation. At 17 weeks her targeted imaging for fetal anomalies (TIFFA) scan revealed left side severe fetal hydrothorax. Again at 29 weeks left pleural effusion was noted. A C-section was performed at 38th week of pregnancy and a male child weighing 2.995 grams was born, with no need for ventilator support

Synthesis, spectral characterization and antioxidant activity of a supramolecular copper (II) complex obtained from pyridine-2, 6- dicarboxylic acid and 3,5-diamino - 1, 2, 4-triazole.

A supramolecular copper (II) compound, (HdatrzH)[Cu (Hdipic) (dipic)].3H2O (1) (Hdatrz = 3,5-diamino-1,2,4- triazole, dipic = pyridine- 2,6-dicarboxylic acid) was synthesized and characterized by elemental analysis, Fourier transformed infrared spectroscopy (FT-IR), UV-Visible spectroscopy, mass spectrometry, proton nuclear magnetic resonance (1H-NMR), thermal analysis, and magnetic susceptibility measurement. The room temperature magnetic susceptibility measurement showed a magnetic moment of 1.67 BM for compound 1, deviating slightly from the spin-only magnetic moment value for Cu (II) ion. Thermogravimetric analysis revealed three decomposition stages for compound 1. The compound showed no activity against all the tested microorganisms. Interestingly, compound 1 exhibited a significant radical scavenging activity (RSA)

Parasiticidal, antifungal and antibacterial activities of Onosma griffithii Vatke

Onosma griffithii was screened for possible pharmacological activities. The crude methanolic extract (MeOH) and its fractions demonstrated parasiticidal activity (IC 50 (ìg/ml ± S.D) = 31.03 ± 0.23) against Leishmania major. Based on the IC 50 values, the potency of the standard drug (Pentamidine) and test fractions were of the order as: Pentamidine > crude extract > n-hexane fraction > ethyl acetate (ETOAc) fraction > chloroform fraction (CHCl3) fraction > n-butanol (BUOH) fraction > aqueous fraction. Similarlymoderate antifungal activity was displayed by the crude methanolic extract against Aspergillus flavus and Fusarium solani. Against the Staphylococcus aureus, the aqueous fraction demonstrated moderate antibacterial activity