Preparation and application of highly porous aerogel-based bioactive materials in dentistry

In this study, the possibility of preparation and application of highly porous silica aerogel-based bioactive materials are presented. The aerogel was combined with hydroxyapatite and p.tricalcium phosphate as bioactive and osteoinductive agents. The porosity of aerogels was in themesoporous region with a maximum pore diameter of 7,4 and 12.7 nm for the composite materials. The newly developed bioactive materials were characterized by scant electron microscopy. The in vitro biological effect of these modified surfaces was also tested on SAOS-2 osteogenic sarcoma cells by confocal laser scanning microscopy.     

Nephritis following shunt operation for hydrocephalus

The ventriculo-atrial (VA) and ventriculo-peritoneal (VP) shunts implanted due to hypertensive hydrocephalus might get infected and be complicated by shunt nephritis. We reviewed the morphological changes in kidney retrospectively in the autopsy materials of our institute for the last 15 years after shunt implantation. Histological examination of the kidney was performed in 26 of these cases having 7 cases with glomerular morphological changes. Thus, the shunt nephritis is a relatively frequent complication of VA or VP shunts implanted due to hydrocephalus. Monitorization and follow-up of kidney function in case of any dysfunction of the shunt may suggest the possibility of shunt infection, and the removal of the infected shunt may protect the development of more severe, septic complications.     

Cyanobacteria-mediated internal eutrophication in shallow Lake Balaton after load reduction

Nutrient loads to large, shallow Lake Balaton have been reduced by 45-50% since mid-1980s. While a delayed, but still surprisingly fast recovery was observed in the hypertrophic western areas of the lake, eutrophication followed sewage diversion from the mesotrophic northern basins. We assessed factors that could lead to this unusual response. The prime reason of the observed biomass increase might be a trend of increasing mean water temperature during late summers and the concurrent invasion of the subtropical cyanobacterium, Cylindrospermopsis raciborskii with superior light and nutrient utilisation capabilities. In the mesotrophic areas, the prerequisite of the unforeseen success of C. raciborskii was the exceptionally high potential of this species to generate internal P load. Specific morphometric features of the lake rather than nutrient loads might substantiate the increasing dominance of the cyanobacterium in these areas. Our results stress the need to consider individual characteristics of aquatic ecosystems during eutrophication management.     

Preparation and characterization of poly(vinyl chloride)–continuous carbon fiber composites

In this article, we report on the preparation and characterization of novel poly(vinyl chloride) (PVC)–carbon fiber (CF) composites. We achieved the reinforcement of PVC matrices with different plasticizer contents using unidirectional continuous CFs by applying a warm press and a cylinder press for the preparation of the PVC–CF composites. We achieved considerable reinforcement of PVC even at a relatively low CF content; for example, the maximum stress (σ_max) of the PVC–CF composite at a 3% CF content was found to be 1.5–2 times higher than that of the PVC matrix. There were great differences among the Young's modulus values of the pure PVC and PVC–CF composites matrices. The absolute Young's modulus values were in the range 1100–1300 MPa at a 3% CF content; these values were almost independent of the plasticizer content. In addition, we found a linear relationship between σ_max and the CF content and also recognized a linear variation of the Young's modulus with the CF content. The adhesion of CF to the PVC matrix was strong in each case, as concluded from the strain–stress curves and the light microscopy and scanning electron microscopy investigations. The mechanical properties of the PVC–CF composites with randomly oriented short (10 mm) fibers were also investigated. At low deformations, the stiffness of the composites improved with increasing CF content. Dynamic mechanical analysis (DMA) was used to determine the glass‐transition temperature (T_g) of the PVC–CF composites. The high increase in the Young's modulus entailed only a mild T_g increase. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanochemically assisted synthesis of pristine Ca(II)Sn(IV)-layered double hydroxides and their amino acid intercalated nanocomposites

Syntheses of Ca(II)Sn(IV)-layered double hydroxides (LDHs) are attempted by the traditional co-precipitation as well as mechanochemical methods. Both the co-precipitation method and the one-step milling operation proved to be unsuccessful; these methods only produced physical mixtures of hydroxides and carbonates of the two metal ions. However, a two-step milling operation (dry milling followed by milling in the presence of minute amount of water) led to successful synthesis, verified by a range of characterisation methods. Surprisingly, it was found that ball-milling was not even necessary; the reaction proceeded on manual grinding of the components in an agate mortar with a pestle. The preparation of nanocomposites through intercalation of the anions of cystine or valine into Ca(II)Sn(IV)-LDH could also be achieved by the two-step milling method verified again by a range of instrumental methods.     

What the #$*%! is a Subsymbol?

In 1988, Smolensky proposed that connectionist processing systems should be understood as operating at what he termed the `subsymbolic' level. Subsymbolic systems should be understood by comparing them to symbolic systems, in Smolensky's view. Up until recently, there have been real problems with analyzing and interpreting the operation of connectionist systems which have undergone training. However, recently published work on a network trained on a set of logic problems originally studied by Bechtel and Abrahamsen (1991) seems to offer the potential to provide a detailed, empirically based answer to questions about the nature of subsymbols. In this paper, a network analysis procedure and the results obtained using it are discussed. This provides the basis for an insight into the nature of subsymbols, which is surprising.     

Direct monitoring of cationic polymerization by temperature,conductivity and permittivity measurements

Summary Direct monitoring of cationic polymerization was accomplished by simultaneous measurement of the average dielectric constant, representing the dipoles, of the conductivity, produced by unpaired ions, and of the temperature, characteristic for reaction rate. The ionogenic equilibria during the living polymerization of isobutylene by 1, 3, 5-tris(2-methoxy-2-propyl)benzen/BCl₃ in CH₂Cl₂ at-25°C were demonstrated. Temperature, resistance and capacitance were measured directly in the reaction mixture by a specially designed instrument.Both the conductivity and the average dielectric constant change characteristically during the living polymerization, indicating the presence and simultaneous change of unpaired ions and strongly polarized species.The differences between the AMI, and the aging technique were demonstrated and explained. In the latter case slow initiation was observed due to the methoxy-chlorine exchange caused by a reaction with BCl₃.The applied direct monitoring method helps to understand the role of polarized and ionic species in polymerizations and related processes.     

Pharmacokinetics of ipriflavone

Ipriflavone administered to rats orally is well absorbed from small intestine via the portal route, distributed widely in tissues, metabolized extensively by oxidation, and eliminated from the body preferentially in urine. The absorption of ipriflavone is less effective in dogs, than in rats. In dogs, the compound absorbed is metabolized in the same way as in rats and the metabolites formed are eliminated largely in faeces, together with unabsorbed ipriflavone. In human, ipriflavone administered orally is rapidly absorbed, and quickly metabolized. The dose is eliminated mainly via the urinary route as metabolites (57% of the dose), and the smaller fraction with the faeces, mostly as ipriflavone (40% of the dose). There is no significant change in the pharmacokinetics of ipriflavone even after multiple dose. In the serum, ipriflavone and its metabolites are primarily bound to albumin, the binding is 94-99% and totally reversible.