Certification of the Melt Flow Index of a Polymeric Reference Material Based on a Proficiency Testing Scheme

In order to be comparable across borders and over time, measurements need be traceable to appropriate and stated references. This paper discusses a proposal of a certification process of a Reference Material (RM) developed by an accredited Brazilian Proficiency Testing (PT) provider and a polymers industry. The RM was prepared for a PT scheme, based on ISO/IEC 17043, and also followed the production requirements of ISO Guide 34. PT Scheme data were evaluated based on ISO 13528 and the certification process followed the Annex B of ISO GUIDE 35. The proposal presented in this paper was based on a certification of the melt flow index of a polymer. The results indicate that certification process was fit for the plastic company purpose and that the use of ANOVA was adequate to establish Certified Reference Material uncertainty.     

Photodegradation of 1-nitropyrene in solution and in the adsorbed state

The photodegradation of the 1-nitropyrene (NPy) has been studied using conventional (Xe and medium pressure Hg lamps) and laser sources (XeCl excimer and Nd-YAG UV). Low energy monochromatic light sources were used to study the early stages of degradation (up to 50% conversion). The medium pressure Hg lamp was used for longer periods of irradiation (up to 6h) and for greater degradation of NPy. The results of our work confirm that degradation occurs by radical mechanism. Aromatic hydroxymethyl, methoxy, hydroxy and nitroso derivatives of pyrene (Py) are created by low energy UV irradiation. After a massive UV irradiation, the Py aromatic system is destroyed and more polar low-molecular compounds are generated. The photochemical method described in this paper, based on irradiation by UV lamp, is therefore, suitable for degradation of fused benzene ring(s) and thus should also be effective for degradation of other nitrated polycyclic aromatic compounds.     

Duodenal content reflux esophagitis in the rat: an animal model for the ulcer-associated cell lineage (UACL)?

We have studied the histological changes observed in the mucosa of 10 rats in the region of a esophagojejunostomy to evaluate it as a model for the ulcer-associated cell lineage (UACL). In man, the UACL has a distinctive morphology, proliferative organization, and pattern of trefoil peptide localization. We have therefore examined these aspects aided by immunohistochemistry and in situ hybridization to the trefoil peptides TFF1, TFF2, and TFF3. Only TFF2 was studied by immunohistochemistry, whereas the mRNAs for all three peptides were examined by in situ hybridization using 35S-labeled riboprobes. The marker MIB-1 to the Ki67 proliferation-related antigen was used to examine the proliferative organization of UACL-like changes. In all cases, columnar epithelialization of the distal esophagus was seen, and in all, glands with morphological and gene expression attributes of the UACL were identified. TFF3 mRNA localized patchily throughout the UACL, whereas TFF1 mRNA was found in the upper portions of the lineage and TFF2 mRNA and its product in the acini. These lineages showed virtually no intrinsic proliferative activity. These appearances are similar to those seen in early human UACL, and we therefore propose this that this represents the first published animal model of this lineage.     

Familial Mediterranean fever: clastogenic plasma factors correlated with increased O2(-)--production by neutrophils

Familial Mediterranean fever (FMF) is an autosomal recessive disease predominantly affecting Armenians and non-Ashkenazi Jews. The disease begins in childhood with paroxysmal attacks of pain and fever accompanied by peritonitis, pleuritis, and synovitis. During the acute phase, there is a massive influx of polymorphonuclear leukocytes into the serosal membranes, connected with degranulation of the neutrophils and with secretion of lysosomal enzymes and pyrogenic substances. An increase in the lipoxygenase product, leukotriene B4, a chemotactic agent, and a decrease in the activity of the inhibitor of chemotaxis, C5a, in serosal fluids have been considered responsible. Previous work from our laboratories had shown that the chromosomal instability observed in blood cultures of patients with FMF is secondary to circulating clastogenic factors (CFs), and that the antioxidant enzyme superoxide dismutase, as well as lipoxygenase inhibitors, reduce the chromosome damaging effects. CFs are observed in chronic inflammatory diseases and in various other pathological conditions accompanied by oxidative stress. Similar clastogenic materials were found in supernatants of neutrophils and monocytes after a respiratory burst and were shown to contain lipid peroxidation products and cytokines. In the present study we compared the clastogenic effects exerted by plasma ultrafiltrates from 20 adult patients with FMF to the unstimulated O2- production of their neutrophils. In comparison to 20 age- and sex-matched controls, which were studied simultaneously, the O2- production by patient's neutrophils was routinely higher than that of controls. The clastogenic effects of patient's plasma, expressed as the number of chromosomal aberrations induced in test cultures of healthy donors, were correlated with the importance of O2- production by their neutrophils (r = 0.5235). Even if the relative contribution of disturbance in arachidonic acid metabolism, neutrophil activation, and CF formation in the disease process remains unclear, the demonstration of oxidative stress in this genetic disorder suggests the use of antioxidants and free radical scavengers, in particular during acute attacks, when the classical colchicine treatment is without effect.     

Monolithically integrated InGaAs-P-I-N InP-MISFET PINFET grown bychloride vapor phase epitaxy

The authors report the preparation and performance of a monolithically integrated InGaAs p-i-n detector InP metal-insulator-semiconductor field-effect transistor (PINFET) receiver. The device was grown by two-step chloride vapor-phase epitaxy. The sensitivity of the receiver was measured as -33.9 and -25.4 dBm at 200 and 600 Mb/s, respectively, at a bit-error-rate of 10^-9 and a wavelength of 1.55 μm. It is noted that the performance of the PINFET receiver is currently limited by the thermal noise of the load resistance R_L, which is 5 kΩ     

Patterned Electroconductive Networks in Ag-Polyamide 6 Composites by Laser Ablation

A simple, fast, and cost-effective method to fabricate conductive paths on insulating Ag-containing polyamide 6 (PA6) composites by laser beam treatment is presented in this study. First, Ag-hybrid microparticles (Ag-MP) with a total metal load of up to 19 wt% are synthesized based on a reactive encapsulation strategy utilizing activated anionic polymerization of ε-caprolactam in solution, in the presence of Ag nanoparticles. Then, the Ag-MP are compression molded into plates (Ag-PL) on which a scanning laser treatment is applied to create conductive paths in their selected parts. A comparison between structural, morphological, and thermal properties of the Ag-MP and the molded Ag-PL composites is performed. The electric conductive properties of the Ag-loaded hybrid materials are investigated before and after laser ablation, and it is concluded that the laser treatment results in selected paths with widths in the range of 500 µm with conductivity values in the range of 1.12 to 8.90 S m⁻¹ while the untreated Ag-PA6 surface remains isolating with conductivity values of 1.27 × 10⁻⁰⁸ S m⁻¹. These results prove that applying laser ablation with controlled parameters on initially insulating Ag-PL composites can efficiently produce conductive line patterns in composite plates.     

Ni@Fe₂O₃ heterodimers: controlled synthesis and magnetically recyclable catalytic application for dehalogenation reactions

Ni@Fe(2)O(3) heterodimer nanoparticles (NPs) were synthesized by thermal decomposition of organometallic reactants. After functionalization, these Ni@Fe(2)O(3) heterodimers became water soluble. The pristine heterodimeric NPs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), M?ssbauer spectroscopy and magnetic susceptibility measurements. A special advantage of the heterodimers lies in the fact that nanodomains of different composition can be used as catalysts for the removal of environmentally hazardous halogenated pollutants.