Synthesis and Crystal Structure of [Pb(phen)(μ-N3)(μ-NO3)]n and Its Thermal Decomposition to PbO Nanoparticles

Nano rods of a new 1D polymeric lead(II) complex containing the Pb₂-(μ-N₃)₂ motif, [Pb(phen)(μ-N₃)(μ-NO₃)]_n (phen?=?1,10-phenanthroline), has been synthesized by a sonochemical method. The new nano-structure was characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. A single crystalline material was obtained by applying a heat gradient to a solution of reagents. The single crystal X-ray data showed the coordination number of the Pb²⁺ ions to be eight (PbN4O4), with the Pb²⁺ ions having “stereo-chemically active” electron lone pairs; the coordination sphere was hemidirected. The chains of [Pb(phen)(μ-N₃)(μ-NO₃)]_n interact with each other via π–π interactions to create a 3D framework. PbO nanoparticles were obtained by thermolysis of 1 at 180?°C with oleic acid as a surfactant. The average diameter of the nanoparticles was estimated to be 33?nm by the Scherrer equation. The morphology and size of the prepared PbO samples were further observed using SEM.     

Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife

An expert meeting was organized by the World Health Organization (WHO) and held in Stockholm on 15-18 June 1997. The objective of this meeting was to derive consensus toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (PCBs) for both human, fish, and wildlife risk assessment. Based on existing literature data, TEFs were (re)evaluated and either revised (mammals) or established (fish and birds). A few mammalian WHO-TEFs were revised, including 1,2,3,7,8-pentachlorinated DD, octachlorinated DD, octachlorinated DF, and PCB 77. These mammalian TEFs are also considered applicable for humans and wild mammalian species. Furthermore, it was concluded that there was insufficient in vivo evidence to continue the use of TEFs for some di-ortho PCBs, as suggested earlier by Ahlborg et al. [Chemosphere 28:1049-1067 (1994)]. In addition, TEFs for fish and birds were determined. The WHO working group attempted to harmonize TEFs across different taxa to the extent possible. However, total synchronization of TEFs was not feasible, as there were orders of a magnitude difference in TEFs between taxa for some compounds. In this respect, the absent or very low response of fish to mono-ortho PCBs is most noticeable compared to mammals and birds. Uncertainties that could compromise the TEF concept were also reviewed, including nonadditive interactions, differences in shape of the dose-response curve, and species responsiveness. In spite of these uncertainties, it was concluded that the TEF concept is still the most plausible and feasible approach for risk assessment of halogenated aromatic hydrocarbons with dioxinlike properties.     

In vitro and in vivo biologic effects of interleukin-3 (IL-3) in follicular low-grade lymphoma

We have taken an enhancer trap approach to identify genes that are expressed in hematopoietic cells and tissues of Drosophila. We conducted a molecular analysis of two P-element insertion strains that have reporter gene expression in embryonic hemocytes, strain 197 and vikingICO. This analysis has determined that viking encodes a collagen type IV gene, alpha2(IV). The viking locus is located adjacent to the previously described DCg1, which encodes collagen alpha1(IV), and in the opposite orientation. The alpha2(IV) and alpha1(IV) collagens are structurally very similar to one another, and to vertebrate type IV collagens. In early development, viking and DCg1 are transcribed in the same tissue-specific pattern, primarily in the hemocytes and fat body cells. Our results suggest that both the alpha1 and alpha2 collagen IV chains may contribute to basement membranes in Drosophila. This work also provides the foundation for a more complete genetic dissection of collagen type IV molecules and their developmental function in Drosophila.     

Use of the international prognostic index and the tumor score to detect poor-risk patients with primary mediastinal large B-cell lymphoma: a study of 37 previously untreated patients

How can enzymes function in the centre of a crowded lens over the many decades of an individual's life when the same proteins are usually turned over in a period of days or h in most other tissues? The discovery that alpha-crystallin could function as a molecular chaperone in-vitro has led to the hypothesis that alpha-crystallin could protect enzyme activities against various stresses. In the laboratory the authors have focused on the effect of alpha-crystallin on the activity of enzymes upon exposure to a chemical or thermal stress. The authors have demonstrated that enzymes are rapidly inactivated by sugars, sugar phosphates, steroids and cyanate. These compounds are elevated in diseases such as diabetes, diarrhoea and renal failure, all of which are risk factors for cataract. alpha-Crystallin has been shown to protect specifically against both chemically- and thermally-induced inactivation. Some enzymes are protected with a stoichiometry of one or two enzyme molecules protected per alpha-crystallin aggregate, consistent with a chaperone-like structure. However with other enzymes a more efficient protection occurs consistent with a micellar structure or binding on the outside of alpha-crystallin molecules. Investigation of complex formation indicates that although stable complex formation between enzymes and alpha-crystallin may be involved in protection of enzymes against thermal inactivation, protection against chemically-induced inactivation may be more dynamic in nature.     

Rheologically determined phase behavior and miscibility of reactively compatibilized poly(ethylene terephthalate)/polypropylene blends

Rheology, phase behavior and morphology of poly(ethylene terephthalate)/polypropylene (PET/PP) blends compatibilized with maleic-anhydrate-grafted-PP (PP-g-MA) and n-butyl-acrylate-glycidyl-methacrylate-ethylene (EBGMA) were studied. According to infrared spectroscopy results, whereas PP-g-MA was merely capable of reacting with hydroxyl groups of PET, epoxy groups of EBGMA could react with both the hydroxyl and carboxyl end groups of PET. The enhanced compatibilizing effect of EBGMA on PET/PP systems over PP-g-MA was also revealed by scanning electron microscopy and mechanical experiments. From frequency and temperature sweep rheological experiments, the dynamic characteristics of the compatibilized blends found to be improved in comparison with those of the uncompatibilized system. Such enhancement was interpreted as a result of the higher miscibility of the compatibilized blends which was further supported by Cole–Cole plot analyses.     

Gaussian matrix elements in a cylindrical harmonic oscillator basis

We derive a formalism, the separation method, for the efficient and accurate calculation of two-body matrix elements for a Gaussian potential in the cylindrical harmonic-oscillator basis. This formalism is of critical importance for Hartree-Fock and Hartree-Fock-Bogoliubov calculations in deformed nuclei using realistic, finite-range effective interactions between nucleons. The results given here are also relevant for microscopic many-body calculations in atomic and molecular physics, as the formalism can be applied to other types of interactions beyond the Gaussian form. The derivation is presented in great detail to emphasize the methodology, which relies on generating functions. The resulting analytical expressions for the Gaussian matrix elements are checked for speed and accuracy as a function of the number of oscillator shells and against direct numerical integration.     

Neural networks for real‐time nonlinear control of a variable geometry turbocharged diesel engine

New engines are submitted to emission standards that are becoming more and more restrictive. Diesel engines are typically equipped with variable geometry turbo‐compressor, exhaust gas recirculation system, high‐pressure common rail system and post‐treatment devices in order to meet these legislative requirements. Consequently, the control of diesel engines becomes a very difficult task involving five to 10 control variables that interact with each other and that are highly nonlinear. Until the present day, the control schemes integrated in the engine's controller are all based on static maps identified by steady‐state engine mapping. Afterward, these schemes are adjusted and calibrated in the vehicle using various control techniques in order to assure a better dynamic response of the engine under dynamic load. In this paper, we are interested in developing a mathematical optimization process that searches for the optimal control scheme under static and dynamic operating conditions. Firstly, we suggest modeling the engine and its emissions using mean value models which require limited experiments and are in good agreement with the experimental data. These models are then used in a dynamic optimization process based on the Broyden–Fletcher–Goldfarb–Shanno algorithm in order to find the optimal control scheme of the engine. The results show a reduction of the engine emissions without deteriorating its performance. Finally, we propose a practical control technique based on neural networks in order to apply these control schemes online to the engine. The results are promising. Copyright © 2007 John Wiley & Sons, Ltd.     

Soluble CD95 in the serum of patients with low and intermediate grade malignant lymphomas: absence of prognostic correlations

Several cytokines and the receptors for some cytokines are involved in the pathogenesis and progression of malignant lymphomas. CD95 (Fas/Apo-1) belongs to the TNF-receptor superfamily and may mediate apoptosis if triggered by Fas-ligand or specific antibodies. Recently soluble CD95 (a splice variant of the surface-bound molecule) was detected in the serum of patients with lymphoid leukemias and other disorders. In this study, we examined the levels of soluble CD95 (SCD95) in a series of patients with untreated malignant lymphomas and attempted to correlate this molecule with clinical, histological and laboratory parameters. The level of SCD95 was determined in the serum of 66 untreated patients with low and intermediate grade malignant lymphomas (NHLs) and in 20 normal controls using a solid phase ELISA. The total group of patients with NHLs had a trend towards increased values of SCD95 compared with normal controls (48.8+/-50.0 versus 75.0+/-136.3 U/ml, p < 0.1). However, among patients with NHL, elevated SCD95 did not correlate with the presence of B-symptoms, clinical stage, histologic subtype, LDH, beta-2 microglobulin, response to therapy or duration of response. We conclude that within the confines of this study, SCD95 has no prognostic value in patients with NHL.     

Thermal, structural and optical properties of new tungsten lead–pyrophosphate glasses

Crystalline lead–pyrophosphate precursor was prepared in aqueous solution from lead nitrate and phosphoric acid and characterized by X-ray diffraction, thermogravimetry and Raman scattering. This crystalline lead–phosphate was then used to prepare glass samples in the binary system Pb₂P₂O₇–WO₃. Dependence of WO₃ content on thermal, structural and optical properties were investigated by thermal analysis (DSC), Raman spectroscopy, UV–visible and near-infrared absorption and M-Line technique to access refractive index values. Incorporation of WO₃ in the lead–pyrophosphate matrix enhances the glass transition temperature and thermal stability against devitrification, favors formation of POW bonds and WO₆ clusters. In addition, optical properties are strongly modified with a redshift of the optical bandgap with WO₃ incorporation as well as an increase of the refractive index from 1.89 to 2.05 in the visible.     

Bacterial cellulose-laponite clay nanocomposites

A novel material comprised of bacterial cellulose (BC) and Laponite clay with different inorganic-organic ratios (m/m) was prepared by the contact of never-dried membranes of BC with a previous dispersion of clay particles in water. Field emission scanning electron microscopy (FE-SEM) data of composite materials revealed an effective adhesion of clay over the surface of BC membrane; inorganic particles also penetrate into the polymer bulk, with a significant change of the surface topography even at 5% of clay loading. As a consequence, the mechanical properties are deeply affected by the presence of clay, increasing the values of the Young modulus and the tensile strength. However the maximum strain is decreased when the clay content is increased in the composite in comparison to pristine BC. The main weight loss step of the composites is shifted towards higher temperatures compared to BC, indicating that the clay particles slightly protect the polymer from thermal and oxidative decomposition.