Dielectric and thermoelastic properties of alkaline-earth fluoride crystals

Summary An extended three-body force shell model is developed and used to make an analysis of the volume dependence of low- and high-frequency dielectric constants and thermoelastic Grüneisen parameters for CaF₂, SrF₂, BaF₂ and PbF₂ crystals. Lorentz-Lorenz and Clausius-Mossotti relations are modified in view of three-body interactions (TBI). Calculated results yield better agreement with the experimental data as compared to those obtained by previous investigators.

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Riassunto Si sviluppa un modello esteso a strati della forza a tre corpi e se ne fa uso per un'analisi della dipendenza dal volume delle costanti dielettriche a bassa e alta frequenza e dei parametri termoelastici di Grüneisen per cristalli di CaF₂, SrF₂, BaF₂ e PbF₂. Si modificano le relazioni di Lorentz-Lorenz e di Clausius-Mossotti in vista delle interazioni a tre corpi (TBI). I risultati calcolati sono in migliore accordo con i dati sperimentali di quelli ottenuti da precedenti studi.

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Резюме Предлагается оболочечная модель для протяженной трех-частичной силы. эта модель используется для анализа обьемной зависимости при низких и высоких частотах диэлектрических постоянных и термо-упругих параметров Грюнайзена для кристаллов CaF₂, SrF₂, BaF₂ и PbF₂. Для трех-частичных взаимодействий модифицируются соотношения Лоренц-Лоренца и Клаузиуса-Москотти. Вычисленные результаты дают лучшее согласие с экспериментальными данными, чем результаты других авторов.

     

Identification of molecular fingerprints of phenylindole derivatives as cytotoxic agents: a multi-QSAR approach

Phenylindole is reported to be an interesting scaffold having promising cytotoxic activities and can overcome the cancer drug resistance possibly via binding to the colchicine binding site of tubulin. In order to find out the molecular fingerprints for the better cytotoxic activity of phenylindole derivatives, multiple validated chemometric modeling approaches namely hologram QSAR (HQSAR), Bayesian classification model, and pharmacophore mapping analyses were applied into a dataset of 102 phenylindole derivatives. The final HQSAR model shows good statistical significance (Q²?=?0.760; R²_Train?=?0.868; R²_Test?=?0.660), and the best pharmacophore hypothesis has the highest regression coefficient value (r?=?0.975) and the lowest RMS value of 0.679. Moreover, the Bayesian model is also statistically validated and robust to discriminate the cytotoxic and non-cytotoxic phenylindoles. These studies suggest that the amine group should be unsubstituted for retaining higher cytotoxicity. The pharmacophore mapping and Bayesian classification study suggest the importance of 2-phenyl group as a ring aromatic feature conducive to cytotoxicity. The steric and hydrophobic effect of long chain linear alkyl group has a positive influence on cytotoxicity as evidenced by the multi-QSAR study. Therefore, this multi-QSAR modeling reported here is beneficial in designing potential phenylindole cytotoxic agents in future.     

Similarity of molecular phenotype between known epilepsy gene LGI1 and disease candidate gene LGI2

Background  

The LGI2 (leucine-rich, glioma inactivated 2) gene, a prime candidate for partial epilepsy with pericentral spikes, belongs to a family encoding secreted, beta-propeller domain proteins with EPTP/EAR epilepsy-associated repeats. In another family member, LGI1 (leucine-rich, glioma inactivated 1) mutations are responsible for autosomal dominant lateral temporal epilepsy (ADLTE). Because a few LGI1 disease mutations described in the literature cause secretion failure, we experimentally analyzed the secretion efficiency and subcellular localization of several LGI1 and LGI2 mutant proteins corresponding to observed non-synonymous single nucleotide polymorphisms (nsSNPs) affecting the signal peptide, the leucine-rich repeats and the EAR propeller.     

Six-coordinate cadmium(II) complex containing a bridging dithiolate ligand: synthesis,crystal structure and antifungal activity study

A mixed-ligand polymeric metal complex of Cd(II) has been prepared by reactions of Cd(NO₃)₂·4H₂O with 1,3-diaminopropane (tn) and potassium salt of 1,1-dicyanoethylene-2,2-dithiolate and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis reveals that the Cd(II) complex crystallizes in monoclinic space group P2₁/n with distorted octahedral coordination geometry. The Cd(II) complex was screened in vitro against fungal pathogens such as Synchytrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans (ATCC10231), and Trichophyton mentagrophytes by the disk diffusion method. The biological testing data of the primary ligand K₂i-MNT·H₂O and [Cd(tn)(i-MNT)]_n indicate that the complex exhibits fungistatic antifungal activity, whereas K₂i-MNT·H₂O has no activity. The fungicidal properties of [Cd(tn)(i-MNT)]_n showed that the cadmium complex was more bioactive than the parent ligand.     

Axisymmetric vibration of single-walled carbon nanotubes in water

A double shell-Stokes flow model is developed to study the axisymmetric vibration of single-walled carbon nanotubes (SWCNTs) immerged in water. In contrast to macroscopic solid-liquid system, a submerged SWCNT is coupled with surrounding water via the van der Waals interaction. It is shown that this unique feature substantially reduces viscous damping of the axisymmetric radial, longitudinal and torsional vibrations and significantly up-shifts the frequency of the radial vibration of an SWCNT. The study offers a theoretical explanation for the experimental observation and molecular dynamics simulations available in particular cases, and provides an efficient modelling tool and useful guidance for the study of the general dynamic behaviour of SWCNTs in a fluid.