Triazine herbicide imprinted monolithic column for capillary electrochromatography

Trietazine was selectively separated from aqueous solution containing the competitor molecule cyanazine, which is similar in size and shape to the template molecule. Structural features of the molecularly imprinted column were figured out by SEM. The influence of the mobile‐phase composition, applied electrical field, and pH of the mobile phase on the recognition of trietazine by the imprinted monolithic polymer has been evaluated, and the imprint effect in the trietazine‐imprinted monolithic polymer was demonstrated by an imprinting factor. The optimized monolithic column resulted in separation of trietazine from a structurally related competitor molecule, cyanazine. In addition, fast separation was obtained within 6 min by applying higher electrical field, with the electrophoretic mobility of 2.97 × 10^?8 m²V^?1s^?1 at pH 11.0.     

Experimental investigation of radiocesium sorption on ceramic clay using a batch method

In this study, radiocesium sorption on ceramic clay was investigated as a function of particle size and initial ¹³⁷Cs concentration using a batch method. Ceramic clay samples taken from the Sö?üt(?nisar) clay deposit were composed of kaolinite, dickite and quartz. The equilibrium time and the liquid–solid ratio were determined as 60 min and 250 mL g^?1, respectively. The distribution coefficients (K _d) for variable liquid–solid ratio and the percentage adsorption (P _Ad) were calculated. The values of K _d and P _Ad ranged from 483 to 3165 mL g^?1 and 34–93%, respectively. The K _d and P _Ad values increased with increasing particle size, but decreased with increasing initial concentration. The sorption data were interpreted in terms of a Langmuir isotherm. The results indicated that the Sö?üt(?nhisar) ceramic clay has good sorption capacity for cesium.     

Reconstruction and crosstalk of protein-protein interaction networks of Wnt and Hedgehog signaling in Drosophila melanogaster

In the last few years, researchers have an intense interest in the evolutionarily conserved signaling pathways which have crucial roles during embryonic development. The most intriguing factor of this interest is that malfunctioning of these signaling pathways (Hedgehog, Notch, Wnt etc.) leads to several human diseases, especially to cancer. This study deals with the β-catenin dependent branch of Wnt signaling and the Hedgehog signaling pathways which offer potential targeting points for cancer drug development. The identification of all proteins functioning in these signaling networks is crucial for the efforts of preventing tumor formation. Here, through integration of protein-protein interaction data and Gene Ontology annotations, Wnt/β-catenin and Hedgehog signaling networks consisting of proteins that have statistically high probability of being biologically related to these signaling pathways were reconstructed in Drosophila melanogaster. Next, by the structural network analyses, the crucial components functioning in these pathways were identified. The proteins Arm, Frizzled receptors (Fz and Fz2), Arr, Apc, Axn, Ci and Ptc were detected as the key proteins in these networks. Futhermore, the hub protein Mer having tumor suppressor function may be proposed as a putative drug target for cancer and deserves further investigation via experimental methods. Finally, the crosstalk analysis between the reconstructed networks reveals that these two signaling networks crosstalk to each other.     

General decay and blowup of solutions for coupled viscoelastic equation of Kirchhoff type with degenerate damping terms

In this work, we consider a nonlinear system of viscoelastic equations of Kirchhoff type with degenerate damping and source terms in a bounded domain. Under suitable assumptions on the initial data, the relaxation functions g_i(i = 1,2) and degenerate damping terms, we obtain global existence of solutions. Then, we prove the general decay result. Finally, we prove the finite time blow‐up result of solutions with negative initial energy. This work generalizes and improves earlier results in the literature.     

On the Schröder–Bernstein property for modules

The well known Schröder–Bernstein Theorem states that any two sets with one to one maps into each other are isomorphic. The question of whether any two (subisomorphic or) direct summand subisomorphic algebraic structures are isomorphic, has long been of interest. Kaplansky asked whether direct summands subisomorphic abelian groups are always isomorphic? The question generated a great deal of interest. The study of this question for the general class of modules has been somewhat limited. We extend the study of this question for modules in this paper. We say that a module Msatisfies the Schröder–Bernstein property (S-B property) if any two direct summands of M which are subisomorphic to direct summands of each other, are isomorphic. We show that a large number of classes of modules satisfy the S-B property. These include the classes of quasi-continuous, directly finite, quasi-discrete and modules with ACC on direct summands. It is also shown that over a Noetherian ring R, every extending module satisfies the S-B property. Among applications, it is proved that the class of rings R for which every R-module satisfies the S-B property is precisely that of pure-semisimple rings. We show that over a commutative domain R, any two quasi-continuous subisomorphic R-modules are isomorphic if and only if R is a PID. We study other conditions related to the S-B property and obtain characterizations of certain classes of rings via those conditions. Examples which delimit and illustrate our results are provided.     

Micelle‐catalyzed reaction of ninhydrin with DL‐valine in the absence and presence of organic solvents

Kinetics of the DL ‐valine‐ninhydrin reaction has been studied spectrophotometrically under varying conditions of [CTAB], [ninhydrin], [DL ‐valine], pH, temperature, and %(v/v) organic solvents (solvents used: 1‐propanol, methylcellosolve, acetonitrile, and dimethyl sulfoxide). Addition of CTAB and increase in the proportion of organic solvents, both showed catalyzing effect on the reaction. The effect of simultaneous presence of CTAB and DMSO in the reaction mixture has also been seen. The rate profiles obtained for solutions containing from 10% to 70% DMSO exhibited clear maxima that shifted progressively to higher concentrations of CTAB. The experimental results are explained in terms of specific solvent effects and the formation of stoichiometric hydrate DMSO · 2H₂O and the inhibitory effect of DMSO on micelle formation. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 634–642, 2006     

Experimental and theoretical studies on the functionalization reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and acid chloride with 2,3-diaminopyridine

The 1H-pyrazole-3-carboxylic acid 2 was converted in good yield (69%) into the corresponding 1H-pyrazole-3-carboxamide 5 via reaction of the acid chloride 3 with 2,3- diaminopyridine (4). A different product, the 3H-imidazo[4,5-b] pyridine derivative 6, was formed from the reaction of 3 with 4 and base in benzene for 5 hours. The structures of the synthesized compounds were determined spectroscopically. The mechanism of the reaction between 3 and 4 was examined theoretically.     

Sur quelques Théorémes globaux en geometrie finslérienne

Résumè Le travail suivant établit des théorèmes globaux relatifs aux variétes finslériennes completes dont le tenseur de courbure vérifie certaines hypothèses. Le théorème de Hopf-Rinow est d’abord démontrè, puis au moyen du calcul variationnel, on établit une géneralisation des théoremes de Myers, de Cartan et de L. W. Green.     

Conformational analysis of XA and AX dipeptides in water by electronic circular dichroism and 1H NMR spectroscopy

We measured the temperature-dependent electronic circular dichroism (ECD) spectra of AX, XA, and XG dipeptides in D2O. The spectra of all XA and AX peptides indicate a substantial population of the polyproline II (PPII) conformation, while the ECD spectra of LG, KG, PG, and AG were found to be quantitatively different from the alanine-based dipeptides. Additional UV absorption data indicate that the ECD spectra of the XG peptides stem from electronic coupling between the peptide and the C-terminal group, and that spectral differences reflect different orientations of the latter. We also measured the 1H NMR spectra of the investigated dipeptides to determine the 3JHalphaNH coupling constants for the C-terminal residue. The observed temperature dependence of the ECD spectra and the respective room-temperature 3JHalphaNH coupling constants were analyzed by a two-state model encompassing PPII and a beta-like conformation. The PPII propensity of alanine in the XA series is only slightly modulated by the N-terminal side chain, and is larger than 50%. As compared to AA, XA peptides containing L, P, S, K V, E, T, and I all cause a relative stabilization of the extended beta-strand conformation. The PPII fractions of XA peptides varied between 0.64 for AA and 0.58 for DA, whereas the PPII fractions of AX peptides were much lower. From the investigated AX peptides, only AL and AQ showed the expected PPII propensity. We found that AT, AI, and AV clearly prefer an extended beta-strand conformation. A quantitative comparison of AA, AAA, and AAAA revealed a hierarchy AAAA > AAA approximately AA for the PPII population, in agreement with predictions from MD calculations and results from Raman optical activity studies (McColl et al. J. Am. Chem. Soc. 2004, 126, 5076).     

PBL as a pedagogical approach for integrated STEM: Evidence from prospective teachers

Problem-based learning (PBL) and science, technology, engineering, and mathematics (STEM) are two acronyms widely visible in education literature today. However, few studies have explored these in connection with one another, specifically with regard to teacher preparation. This study investigated how 47 prospective elementary teachers developed PBL units and how they integrated STEM and other disciplines into those units. It also addressed the affordances and constraints of integrated STEM as perceived by the prospective elementary teachers. Data sources in this multimethod study included PBL units and interviews. Findings revealed that all of the units integrated at least two of the STEM disciplines, as well as literacy, in a variety of ways. The prospective teachers articulated perceived benefits of integrated STEM, such as: making connections across content areas, preparing students for the real world, teaching students that failure is not a bad thing, and providing future opportunities. They also addressed perceived barriers of integrated STEM, such as: having limited experience with the content, diminishing the effect of individual content areas, and needing better curriculum alignment. Overall, this study provides evidence that PBL can be a pedagogical approach to integrate STEM. Implications for teachers, teacher educators, and curriculum specialists are discussed.