Planar and non-planar ion acoustic shock waves in electron-positron-ion plasmas

Ion acoustic shock waves (IASW's) are studied in an unmagnetized plasma consisting of electrons, positrons and adiabatically hot positive ions. This is done by deriving the Kortweg-deVries-Burger (KdVB) equation under the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of ion acoustic shock wave is maximum for spherical, intermediate for cylindrical, and minimum for planar geometry. It is observed that the positron concentration, ratio of ion to electron temperature, and the plasma kinematic viscosity significantly modifies the shock structure. Finally, it is found that the temporal evolution of the non-planar IASW's is quite different by comparison with the planar geometry. The relevance of the present study with regard to the dense astrophysical environments is also pointed out.     

Synthesis,Spectroscopic Characterization,Thermogravimetric and Biological Activity Evaluation of Te(Ⅳ),Se(Ⅳ),V(Ⅲ),Nb(Ⅴ),Ta(Ⅴ)Complexes With Indole-3-Acetic Acid Plant Hormone Ligand

Te(Ⅳ), Se(Ⅳ), V(Ⅲ), Nb(Ⅴ) and Ta(Ⅴ) complexes of indole-3-acetic acid (IAAH) ligand were synthesized, characterized by elemental analysis and various spectroscopic techniques like, IR, 1H-NMR, X-ray powder diffraction, UV-Visible, thermogravimetry analysis, magnetic measurements, molar conductance and surface morphology using SEM. All the synthesized complexes of IAAH ligand have 1∶2 stoichiometry of the types [Te(IAA)₂(NH₃)₂]·2Cl (Ⅰ), [Se(IAA)₂(NH₃)₂]·2Cl (Ⅱ), [V(IAA)₂(NH₃)(Cl)] (Ⅲ), [Nb(IAA)₂(Cl)₃] (Ⅳ), and [Ta(IAA)₂(Cl)₃] (Ⅴ). Spectral analysis indicates octahedral geometry for the Te(Ⅳ), Se(Ⅳ) and V(Ⅲ) complexes, whereas both Nb(Ⅴ) and Ta(Ⅴ) have a seven-coordination. The bonding sites are the oxygen atoms of carboxylate group for the deprotonated indole-3-acetic acid (IAA) ligand. The thermogravimetry analysis studies gave evidence for the presence of other coordinated molecules (Cl or NH₃) in the composition of IAA complexes, which were further supported by IR and micro analytical measurements. The higher molar conductance data of tellurium and selenium (Ⅳ) complexes reveal that these chelates are electrolytes, while low conductivity values for the vanadium(Ⅲ), niobium and tantalum(Ⅴ) chelates indicated a non-electrolytes. To test the antibacterial property of the five complexes in this study, four bacterial strains Klebsiella (G-), Escherichia coli (G-), Staphylococcus aureus (G+) and Staphylococcus epidermidis (G+) were used in the investigation. The effects of the five complexes in the cytotoxicity of Caco-2 and Mcf-7 human cancer cell lines were studied Neutral red uptake assay for the estimation of cell viability/cytotoxicity protocol.     

Spontaneous Chirality Induction in the Assembly of a Single Layer 2D Network with Switchable Pores

Although two-dimensional (2D) chiral sheet structures are attractive because of their unique chemical and physical properties, single layer 2D chiral network structures with switchable pore interior remain elusive. Here we report spontaneous chirality induction in a single layer 2D network structure formed from the self-assembly of tetrapod azobenzene molecules. The chirality induction arises from multiple sublayers slipped in a preferred direction in which the sublayer consists of unidentical molecular arrangements in the in-plane a and b directions, breaking both the plane of symmetry and inversion symmetry. The protruded azobenzene units in the pore interior can be selectively isomerized upon UV irradiation, resulting in a reversible deformation of the chiral pores while maintaining the 2D frameworks. The chiral network can thus selectively entrap one enantiomer from a racemic solution with near perfect enantioselectivity, and then release it upon UV irradiation.     

Solvent-Free Mechanochemical Synthesis of High Transition Biphenyltetracarboxydiimide Liquid Crystals

A series of high temperature alkyl and alkoxy biphenyltetracarboxydiimide liquid crystals have been prepared under ball mill method using solvent-free mechanochemical approach. The thermal properties of the prepared compounds were investigated by deferential scanning calorimetry (DSC) measurements and the textures were identified by polarized optical microscope (POM). The compounds showed smectic mesomorphic behaviour. The results showed the increasing nature of transition temperature Cr-SmC with chain length with increments of the SmC mesophase range. However, the mesophase range of the SmA was decreased with the terminal chain length either for the alkyl or alkoxy terminal groups. Moreover, the DFT theoretical calculations have been conducted give a detailed projection of the structure of the prepared compounds. A conformational investigation of the biphenyl part has been studied. A deep illustration of the experimental mesomorphic behaviour has been discussed in terms of the calculated aspect ratio. A projection of the frontier molecular orbitals as well as molecular electrostatic potential has been studied to show the effect of the polarity of the terminal chains on the level and the gap of the FMOs and the distribution of electrostatic charges on the prepared molecules.     

One‐Pot Synthesis of Some Dynamic 2‐Substituted Benzoxazinones and Their Corresponding Qinazolinones of Anticipated Biological Activity

Reactions of 6‐bromo‐2‐isopropyl‐4(3H)‐3,1‐benzoxazin‐4‐one toward mono‐ and di‐dentate nitrogen nucleophiles, e.g. primary aliphatic and aromatic amines, 1,2‐phenylenediamine, hydrazine hydrate, and formamide, have been investigated and afford the corresponding quinazolinones which are expected to have some interesting biological activity. The behavior of 3, 1‐benzoxazin‐4‐one toward active methylene compounds, namely, acetylacetone in basic medium has been studied and gave 3‐acetylquinoline. The last reaction is considered as an illustrative model of heterocyclic transformation reactions.     

Quantitative estimation of calcite in limestones by differential thermal analysis

A quantitative method is presented for the estimation of calcite in limestones by differential thermal analysis, using calcium hydroxide as an internal standard. The effects of variations due to particle size and impurities such as quartz, iron oxide, organic material, dolomite, magnesite, gypsum and phosphates are discussed.

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Zusammenfassung Es wurde eine quantitative Methode zur Ermittlung von Kalzit im Kalkstein durch Differentialthermoanalyse unter Anwendung von Kalziumhydroxyd als inneren Standard vorgestellt. Der Einfluß von durch unterschiedliche Teilchengröße und Verunreinigungen, wie Quarz, Eisenoxyd, organische Stoffe, Dolomit, Magnesit, Gips und Phosphat hervorgerufenen Veränderungen wurde erörtert.

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Résumé On propose une méthode de dosage par ATD de la calcite dans les roches calcaires en utilisant l'hydroxyde de calcium comme étalon interne. On discute l'influence de la taille des particles et de la nature des impuretés: quartz, oxyde de fer, corps organiques, gypse, dolomite, magnésite et phosphates.

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Low divergence angle and low jitter 40 GHz AlGaInAs/InP 1.55 μm mode-locked lasers

We demonstrate a novel (to the best of our knowledge) 40?GHz passively mode-locked AlGaInAs/InP 1.55?μm laser with a low divergence angle (12.7°×26.3°), timing jitter of 1.2?ps (10?kHz-100?MHz), and a radio frequency linewidth of 25?kHz.     

Radioprotective Effects of Kelulut Honey in Zebrafish Model

Large doses of ionizing radiation can damage human tissues. Therefore, there is a need to investigate the radiation effects as well as identify effective and non-toxic radioprotectors. This study evaluated the radioprotective effects of Kelulut honey (KH) from stingless bee (Trigona sp.) on zebrafish (Danio rerio) embryos. Viable zebrafish embryos at 24 hpf were dechorionated and divided into four groups, namely untreated and non-irradiated, untreated and irradiated, KH pre-treatment and amifostine pre-treatment. The embryos were first treated with KH (8 mg/mL) or amifostine (4 mM) before irradiation at doses of 11 Gy to 20 Gy using gamma ray source, caesium-137 (¹³⁷Cs). Lethality and abnormality analysis were performed on all of the embryos in the study. Immunohistochemistry assay was also performed using selected proteins, namely γ-H2AX and caspase-3, to investigate DNA damages and incidences of apoptosis. KH was found to reduce coagulation effects at up to 20 Gy in the lethality analysis. The embryos developed combinations of abnormality, namely microphthalmia (M), body curvature and microphthalmia (BM), body curvature with microphthalmia and microcephaly (BMC), microphthalmia and pericardial oedema (MO), pericardial oedema (O), microphthalmia with microcephaly and pericardial oedema (MCO) and all of the abnormalities (AA). There were more abnormalities developed from 24 to 72 h (h) post-irradiation in all groups. At 96 h post-irradiation, KH was identified to reduce body curvature effect in the irradiated embryos (up to 16 Gy). γ-H2AX and caspase-3 intensities in the embryos pre-treated with KH were also found to be lower than the untreated group at gamma irradiation doses of 11 Gy to 20 Gy and 11 Gy to 19 Gy, respectively. KH was proven to increase the survival rate of zebrafish embryos and exhibited protection against organ-specific abnormality. KH was also found to possess cellular protective mechanism by reducing DNA damage and apoptosis proteins expression.     

Electrochemical synthesis for new thiosemicarbazide complexes,spectroscopy, cyclic voltammetry,structural properties,and in silico study

A new thiosemicarbazide derivative ligand (HDCTS) was prepared from the reaction between 2,4‐dinitrophenylhydrazine and 4‐chlorophenyl isothiocyanate. Co(II) and Cu(II) complexes were synthesized from HDCTS derivative by electrochemical method to reach preferable yield in a safe environment. The new complexes as well as the original ligand were fully characterized to establish their chemical formulae. The spectral (infrared, Raman, mass, and ultraviolet–visible), analytical (elemental, thermogravimetric analysis [TGA], and cyclic voltammetry), and conformational techniques were implemented for characterization. According to spectral data and magnetic moments, the octahedral arrangement was proposed around metals through mono‐negative bidentate mode of bonding. TGA discriminates and quantitatively evaluates the presence of water molecules within two complexes. Electrochemical study was interested for all new compounds and suggests the electrode couples to be close for quasi‐reversible behavior. Elaborated conformational study was displayed to extract significant characteristics, which assert firstly on the mode of bonding inside the complexes. The perfect distribution of NH and CS groups inside the optimized structures facilitates their coordination as spectrally proposed. Crystal explorer program was used to investigate the degree of contact between molecules inside crystal packing systems. Effective contribution in surface contact feature was noticed from O and Cl atoms. A certified in silico study concerning the docking feature of new compounds against effective proteins in allergy and inflammation diseases was done. According to data exported, a promising anti‐allergic or anti‐inflammatory efficiency is expected strongly from Cu(II)–DCTS complex.