Synthesis of novel poly 2‐vinylpyridine‐mixed metal complexes and studying their effect as antitumor chemotherapeutic agents,part 2

The poly2‐vinylpyridine and cationic polymer‐mixed metal complexes (P2VPMC) have been prepared and characterized by analytical measurement such as: molecular weight, elemental analysis, IR‐spectroscopy, NMR‐spectroscopy, XRD, and UV. The degree of N‐alkylation of poly vinyl pyridine (P‐2VP) was 10% determined by chlorine content according to elemental microanalysis. Through ICP instrument the complexation between P‐2VPC and the mixed metal chlorides was proven. The structure of the samples was characterized using X‐ray diffraction. It was found that the complexes have amorphous properties. The antitumor activity of this compound was examined in vitro on cell lines. The results reflect pronounced cytotoxicity of P‐2VPMC against animal experimental EAC cells line, and human, HeLa, HCT116 and Hep‐G2, cell lines. Antitumor activity of the novel compound as applied on mice bearing Ehrlich solid carcinoma, revealed delays tumor growth compared with untreated animals and decreases tumor volume. The antitumor activity of the P2VPMC might be due to its ability to pass through the membrane and interact with, DNA causing cross‐linking action which might be the key factor for great antitumor activity of the P2VPMC compound. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modulation of in vitro and in vivo T-cell responses by transferrin-gallium and gallium nitrate

Gallium is a group IIIa metal that has efficacy in the therapy of malignant disorders such as lymphoma and urothelial tract tumors. Preclinical studies also indicate a role for gallium in autoimmune disorders, suggesting that gallium is able to modulate T-cell immune reactivity. The purpose of this study was to examine the in vitro and in vivo immunomodulatory action of gallium on T-cell function. Since gallium binds to transferrin in vivo, in vitro studies evaluated the effect of transferrin-gallium (Tf-Ga) on human T cells. Tf-Ga inhibited the mitogen-induced proliferative response of peripheral blood mononuclear cells (PBMC) in a dose-dependent fashion. Alloantigen-induced proliferation was also potently suppressed when evaluated in a mixed lymphocyte culture assay. Tf-Ga affected a significant reduction in the density of IL-2 receptors on activated T cells and a slight reduction in the number of CD3+/CD25+ T cells in PHA-stimulated cultures. Neither secretion of interleukin-2 (IL-2) nor the induction of IL-2-stimulated lymphokine-activated killer activity, however, was inhibited by Tf-Ga. Tf-Ga produced significant upregulation of the transferrin receptor (CD71) in T cells as determined by flow cytometric analysis and northern blot assay, but did not affect the percentage of CD3+/ CD71+ T cells after mitogen stimulation. To assess the in vivo effects of gallium on alloreactive T cells, we evaluated the immunosuppressive effect of gallium in a murine model of graft-versus-host disease (GVHD). Administration of gallium significantly prolonged survival in mice undergoing severe GVHD, suggesting that gallium can ameliorate GVH reactivity. Collectively, these data demonstrate that, at clinically achievable concentrations, Tf-Ga potently inhibits T-cell activation and that this immunosuppressive property of gallium may be of adjunctive therapeutic value in the management of disorders characterized by the presence of autoreactive or alloreactive T-cell populations.     

Comparison of total ozone column observations from space-borne Ozone Monitoring Instrument with ground-based Dobson Ozone Spectrophotometer measurements at an urban location in Indo-Gangetic Basin

This article presents a comparison analysis of OMIT (Ozone Monitoring Instrument retrieved overpass total ozone column (TOC)), and DOST (Dobson Ozone Spectrophotometer observed TOC) over Delhi during a period from October 2004 to June 2011. Megacity Delhi, located in Indo-Gangetic Basin, is an important site for comparison of ground-based and satellite retrieved TOCs due to significant anthropogenic emissions of ozone precursors, large shift in seasons, and large-scale crop residue burning in the region. DOST and OMIT data show an overall bias of 3.07% and significant correlation with coefficient of determination R² = 0.73. Large seasonal fluctuations in the biases and correlations have been observed ranging from 2.46% (winter) to 3.82% (spring), and R² = 0.84 (winter) to R² = 0.09 (summer), respectively. The large biases are attributed to changes in temperature, cloud cover, pollutants emissions from urban area, and crop-residue burning events. We also find notable variations in correlations between the datasets due to the varying burden of absorbing aerosols from open field crop-residue burning. The R² has changed from 0.67 (for aerosol optical depth, AOD 1.5–3.5) to 0.77 (for AOD 0–0.99). The dependence of the bias on solar zenith angle, cloud fraction, and satellite distance is also discussed. A simple linear regression analysis is applied to check the linkage between DOST and OMIT. The influence of atmospheric air temperature and relative humidity on OMIT at different pressure levels between 1000 and 20 hPa has been discussed.     

The Influence of pH on the Morphology and Electrochemical Behavior of Pd–Pt thin Films Prepared by Electro-less Deposition

Protection of Metals and Physical Chemistry of Surfaces - Pd–Pt thin films over titanium substrates were coated through electro-less deposition method as a function of pH values. It is...     

A comparative study of the stress relaxation in aged and un-aged high-purity aluminium polycrystals

Stress relaxation in 99.996% aluminium polycrystals of average grain-diameter 0.30, 0.42 and 0.51 mm, annealed at 500°C and aged for six months at room temperature, has been studied as a function of initial stress level from which relaxation at constant strain was allowed to start. Data were also obtained with annealed but un-aged aluminium specimens of the same purity and grain size for comparison. The grain size has no notable effect on the strength parameters and stress-relaxation rate in both aged and un-aged aluminium. The room-temperature ageing causes significant increase in the yield stress, while tensile strength and fracture stress remain un-effected. The intrinsic height of the thermally-activable energy barrier (1.64 eV) evaluated for aged aluminium is comparable with that (1.94 eV) for un-aged aluminium, and is of the order of magnitude for recovery processes. In aged specimens, the relaxation rate at a given stress level is 30% larger and associated activation volume is accordingly smaller than that in un-aged specimens. This is most probably due to the diffusion of vacancies and/or residual gaseous and metallic impurity atoms to the cores of edge dislocations in aged specimens.     

Observation of mechanical percolation in functionalized graphene oxide/elastomer composites

We have covalently functionalized graphene oxide (GO) with octadecylamine (ODA) to form GO–ODA. This material can be dispersed in tetrahydrofuran (THF) and subsequently formed into composites with polymers such as thermoplastic polyurethane (TPU). We have characterized the mechanical properties of composites of GO–ODA in TPU. No increase in stiffness was observed at loading levels below 2.5 vol%. Reinforcement appeared to start sharply at this volume fraction and subsequently increased as a power law with increasing volume fraction. This behavior is typical of percolation and shows that the low-strain stress is not increased until the functionalized graphene flakes form a percolating network. Slightly different behavior is observed for properties related to material failure. The ultimate tensile strength increased linearly with graphene content up to the percolation threshold before subsequently falling off. Similarly the strain at break was constant below the percolation threshold but fell off dramatically above it. This work shows the importance of network formation in the reinforcement of elastomeric materials.     

Power budget analysis of dual/single feeder fiber WDMPON

This paper investigates how to reduce the cost of wavelength division multiplexing passive optical network （WDM- PON） by comparing the transmission performance of bidirectional single feeder fiber and dual feeder fiber. Comparison is performed on the basis of power budgeting and cost of both arrangements. Simulation results using Optisystem show that the performance of a single feeder fiber is almost equivalent to that of a dual feeder fiber. Therefore, the single feeder fiber WDM-PON can efficiently replace the dual feeder fiber WDM-PON with the minimum deterioration in system performance and reduction in cost.     

Early dropout prediction using data mining: a case study with high school students

Early prediction of school dropout is a serious problem in education, but it is not an easy issue to resolve. On the one hand, there are many factors that can influence student retention. On the other hand, the traditional classification approach used to solve this problem normally has to be implemented at the end of the course to gather maximum information in order to achieve the highest accuracy. In this paper, we propose a methodology and a specific classification algorithm to discover comprehensible prediction models of student dropout as soon as possible. We used data gathered from 419 high schools students in Mexico. We carried out several experiments to predict dropout at different steps of the course, to select the best indicators of dropout and to compare our proposed algorithm versus some classical and imbalanced well‐known classification algorithms. Results show that our algorithm was capable of predicting student dropout within the first 4–6 weeks of the course and trustworthy enough to be used in an early warning system.     

All-organic PANI–DBSA/PVDF dielectric composites with unique electrical properties

Novel all-organic polymer high-dielectric permittivity composites of polyaniline (PANI)/poly (vinylidene fluoride) (PVDF) were prepared by solution method and their dielectric and electric properties were studied over the wide ranges of temperatures and frequencies. To improve the interface bonding between two polymers, dodecylbenzenesulfonic acid (DBSA), a bulky molecule containing a polar head and a long non-polar chain was used both as a surfactant and as dopant in polyaniline (PANI) synthesis. Synthesized conducting PANI–DBSA particles were dispersed in poly(vinylidene fluoride) (PVDF) matrix to form an all-organic composite with different PANI–DBSA concentrations. Near the percolation threshold, the dielectric permittivity of the composites at 100 Hz frequency and room temperature was as high as 170, while the dielectric loss tangent value was as low as 0.9. Like typical percolation system, composites experienced high dielectric permittivity at low filler concentrations. However, their dielectric loss tangent was low enough to match with non-percolative ceramic filler-based polymer composites. Maximum electrical conductivity at 24 wt% of PANI–DBSA was mere 10^?6 S/cm, a remarkably low value for percolative-type composites. Increase in the dielectric permittivity of the composites with increase in temperature from 25 to 115 °C for different PANI–DBSA concentrations was always in the same range of 50–60 %. However, the degree of increase in the electrical conductivity with the temperature was more prominent at low filler concentrations compared with high filler concentrations. Distinct electrical and their unique thermal dependence were attributed to an improved interface between the filler and the polymer matrix.