Band propagation, scaling laws and phase transition in a precipitate system. I: Experimental study

In the first part of this work, we present an experimental study of the precipitation/redissolution reaction-diffusion system of initially separated components in two distinct organic gels: agar and gelatin. The system is prepared by diffusing a concentrated ammonia solution into a gel matrix that contains nickel sulfate. In agar, the system exhibits a pulse propagation due to the concomitant precipitation reaction between Ni(II) and hydroxide ions and redissolution due to ammonia. At a later stage of propagation, a transition to Liesegang banding is shown to take place. The dynamics of the distance traveled by the precipitation pulse, its width, and mass are shown to exhibit power laws. Moreover, the mass of the bands is shown to oscillate in time, indicating the emergence of a complex mass enrichment mechanism of the formed Liesegang bands. At the microscopic level, we show evidence that the system undergoes a continuous polymorphic transition concomitant with a morphological change whereby the solid in the pulse, which consists of nanospheres of α-nickel hydroxide transforms to form the bands, which consists of larger platelets of β-nickel hydroxide. This clearly indicates the existence of a dynamic Ostwald ripening mechanism that underlies the dynamics on both scales. On the other hand, in gelatin, although we can still obtain similar power laws as in the case of agar, no transition to bands was observed. It is shown that in this case, the propagating pulse is made of nanoparticles of α-nickel hydroxide with an average diameter ~50 nm.     

Reversible and irreversible denaturation processes in globular proteins: from collective to molecular spectroscopic analysis

Different spectroscopic techniques were applied for studying the structural properties of lysozyme in salt‐free aqueous solutions. The results of vibrational and Brillouin scattering measurements were compared to obtain both single‐molecule and collective properties of the solutions. The characterization of the protein system, from the conformation of the polypeptide chain to the exposure of side chains to the solvent and the arrangement of the solution network, was then achieved in the range 25–85 °C. Through the analysis of the indole breathing mode, a different environment for the six tryptophan residues of an unfolded lysozyme could be evidenced. Short and long exposures to high temperatures were used to modulate the competition between the thermally induced reversible and irreversible denaturation processes. These different thermal treatments were applied to distinguish between the effects of global unfolding of the single molecule from those of self‐aggregation and gel formation. It has been observed that clusterization occurs at melting temperatures with slow kinetics; also, aggregates evolve from the completely unfolded state of the protein and lead to a sensitive increase in viscosity. This effect probably hinders any further conformational rearrangement of the molecules in the aggregate; thus as a consequence, the disordered structure of clusters does not change to give the β‐sheet organization, characteristic of filaments or fibrils. Copyright © 2011 John Wiley & Sons, Ltd.     

Scaffold Repurposing of In-House Small Molecule Candidates Leads to Discovery of First-in-Class CDK-1/HER-2 Dual Inhibitors: In Vitro and In Silico Screening

Recently, multitargeted drugs are considered a potential approach in treating cancer. In this study, twelve in-house indole-based derivatives were preliminary evaluated for their inhibitory activities over VEGFR-2, CDK-1/cyclin B and HER-2. Compound 15l showed the most inhibitory activities among the tested derivatives over CDK-1/cyclin B and HER-2. Compound 15l was tested for its selectivity in a small kinase panel. It showed dual selectivity for CDK-1/cyclin B and HER-2. Moreover, in vitro cytotoxicity assay was assessed for the selected series against nine NCI cell lines. Compound 15l showed the most potent inhibitory activities among the tested compounds. A deep in silico molecular docking study was conducted for compound 15l to identify the possible binding modes into CDK-1/cyclin B and HER-2. The docking results revealed that compound 15l displayed interesting binding modes with the key amino acids in the binding sites of both kinases. In vitro and in silico studies demonstrate the indole-based derivative 15l as a selective dual CDK-1 and HER-2 inhibitor. This emphasizes a new challenge in drug development strategies and signals a significant milestone for further structural and molecular optimization of these indole-based derivatives in order to achieve a drug-like property.     

Covalent and electrostatic incorporation of amines into hypercrosslinked polymers for increased CO2 selectivity

Two methods of incorporating functional groups rich in nitrogen into low cost microporous hypercrosslinked polymers (HCPs) have been evaluated and the effects on the carbon dioxide CO₂/N₂ IAST selectivity were measured. Electrostatic incorporation of an ammonium salt into a sulfonic acid-containing HCP polymer afforded a static CO₂ uptake of 2.5 mmol g⁻¹ with a CO₂/N₂ IAST selectivity of 42:1 at 1 bar and 298 K. Using column breakthrough measurements with a 15:85 CO₂/N₂ mixture at 298 K and 1 bar, a selectivity of 17:1 was obtained. However, varying the counterion resulted in polymers with lower CO₂/N₂ selectivity values. Decoration of the parent polymer with CO₂-philic imidazole followed by electrostatic ammonium salt incorporation blocked some of the micropores reducing the selectivity which re-emphasizes the role and importance of pore width for CO₂/N₂ selectivity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2513–2521     

Carbon nanotubes,science and technology part (I) structure,synthesis and characterisation

Since their discovery in 1991 by the Japanese scientist “Sumio Iijima”, carbon nanotubes have been of great interest, both from a fundamental point of view and for future applications. Different types of carbon nanotubes can be produced in various ways. Economically feasible large-scale production and purification techniques are still under development. Carbon nanotubes are discussed in this review in terms of history, types, structure, synthesis and characterisation methods. Carbon nanotubes have attracted the fancy of many scientists worldwide. The unique and unusual properties of these structures make them a unique material with a whole range of promising applications.     

Cyanothioacetanilide Intermediates in Heterocyclic Synthesis,Part 1: Synthesis and Biological Evaluation of Some Novel Thiazole,Thiophene, Pyrazole,and Pyrazolo[1,5-a]Pyrimidine Derivatives

Some novel thiophenes (4a,b, 5, and 9a,b) were obtained from the cycloalkylation of the thiocarbamoyl group in the cyanothioacetanilide derivative (1) with α-halocarbonyl compounds. Also, the reaction of cyanothioacetanilide derivative with phenyl isothiocyanate in the presence of potassium hydroxide followed by in situ heterocyclization of the resulting adduct with α-halocarbonyl compounds furnished the corresponding thiazole (12, 14, and 15), pyrazole (19), and pyraozlo[1,5-a]pyrimidine (22, 25, and 26) derivatives. Compounds (4b, 5, 9a, 12, 13, 18, 22, 25, and 26) were tested to evaluate their antimicrobial activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis,characterization, and anticancer activity of some azole‐heterocyclic complexes with gold(III), palladium(II), nickel(II), and copper(II) metal ions

Four new complexes of Au(III), Pd(II), Ni(II), and Cu(II) ions were synthesized, derived from a novel heterocyclic ligand (L) that has both triazole and tetrazole rings. The ligand synthesis was through successive steps to achieve both heterocyclic rings. The synthesized compounds were characterized using conventional techniques like infrared, ultra violet—visible and proton/carbon nuclear magnetic resonance spectroscopy, metal and thermal analyses, and molar conductivity. All complexes were suggested to have square planar geometry, gold, nickel, and palladium complexes were salts while copper neutral complexes have the chemical formulas; [AuL₂]Cl.2H₂O, [PdL₂]Cl₂.2H₂O, [NiL₂]Cl₂.2H₂O, and [CuL₂]. The cytotoxic effect was studied on breast cancer cell line (MCF‐7 cell line) at different concentrations by using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay method, for the ligand (L) and complexes. The results showed that gold(III) and nickel(II) complexes have the highest cytotoxicity among all compounds against cancer cell lines.     

Effects of an admixture and fast neutron irradiation on thermal properties of sodium potassium sulphate crystals

The differential thermal analysis curves and the specific heat at constant pressure,C _p, of pure and Cu²⁺-doped sodium potassium sulphate crystals were studied. Different neutron fluences were used up to 2.6×10¹⁰ n/cm², in the temperature range 300–500 K. Impurity incorporation generally increased the specific heat up to a maximum at 5% Cu²⁺ content. The peaks for the doped crystals were shifted to lower temperature as a result of neutron irradiation. This behaviour is discussed on the basis of defects induced by irradiation.

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Zusammenfassung Es wurden die DTA-Kurven und die spezifische Wärme bei konstantem DruckC _p von reinen, mit Cu²⁺ versetzten Natriumkaliumsulfatkristallen untersucht. Im Temperaturbereich 300–500 K wurden verschiedene Neutronenströme bis zu 2,6×10¹⁰ n/cm² verwendet. Der Einbau von Verunreinigungen erhöht im allgemeinen die spezifische Wärme bis zu einem Maximum bei einem Cu²⁺ Gehalt von 5%. Im Ergebnis der Neutronenbestrahlung verschieben sich die Peaks für die versetzten Kristalle in Richtung niedrigerer Temperaturen. Dieses Verhalten wird auf der Basis strahlungsinduzierter Defekte besprochen.

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_p . 300–500 2,6 · 10¹⁰ n/². 5%. , . , .

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It is a great pleasure for us to express our deepest gratitude to Prof. Dr. Younis S. Selim for his guidance throughout this work and for providing the irradiation facilities.     

Light‐mediated DNA Repair Prevents UVB‐induced Cell Cycle Arrest in Embryos of the Crustacean Macrobrachium olfersi

High levels of ultraviolet‐B (UVB) radiation can negatively affect aquatic animals. Macrobrachium olfersi is a prawn that lives in clear freshwaters and during the breeding season, females carry eggs in an external brood pouch. Therefore, we hypothesize that eggs are also exposed to environmental UVB radiation. The aim of this study was to investigate whether UVB radiation induces DNA damage and compromises cell cycle in embryos of M. olfersi. In laboratory, UVB irradiance (310 mW. cm^?2) that embryos receive in the natural environment was simulated. After irradiation, embryos were kept under different light conditions in order to recognize the presence of cell repair. UVB radiation induces DNA damage, specifically thymine dimers. After 48 h of UVB exposure, a significant decrease in the level of these dimers was observed in embryos kept under visible light while it remained constant in the dark. Moreover, under visible light and darkness, a decrease in proliferation was observed after 48 h of irradiation. An increase in PCNA expression and decrease in p53 expression were observed after, respectively, 1 and 48 h of exposure. Our results showed that UVB radiation disturbs the cell cycle and induces DNA damage in M. olfersi embryos. However, under visible light these embryos showed successful DNA repair.