Raman Spectra and Ancient Life: Vibrational ID Profiles of Fossilized (Bone) Tissues

Raman micro-spectroscopy is a non-destructive and non-contact analytical technique that combines microscopy and spectroscopy, thus providing a potential for non-invasive and in situ molecular identification, even over heterogeneous and rare samples such as fossilized tissues. Recently, chemical imaging techniques have become an increasingly popular tool for characterizing trace elements, isotopic information, and organic markers in fossils. Raman spectroscopy also shows a growing potential in understanding bone microstructure, chemical composition, and mineral assemblance affected by diagenetic processes. In our lab, we have investigated a wide range of different fossil tissues, mainly of Mesozoic vertebrates (from Jurassic through Cretaceous). Besides standard spectra of sedimentary rocks, including pigment contamination, our Raman spectra also exhibit interesting spectral features in the 1200–1800 cm⁻¹ spectral range, where Raman bands of proteins, nucleic acids, and other organic molecules can be identified. In the present study, we discuss both a possible origin of the observed bands of ancient organic residues and difficulties with definition of the specific spectral markers in fossilized soft and hard tissues.     

Combined Therapy with Simvastatin- and Coenzyme-Q10-Loaded Nanoparticles Upregulates the Akt-eNOS Pathway in Experimental Metabolic Syndrome

In addition to their LDL-cholesterol-lowering effect, statins have pleiotropic beneficial effects on the cardiovascular system. However, long-term treatment with statins may be associated with serious side effects. With the aim to make statin therapy more effective, we studied the effects of simvastatin- and coenzyme-Q10-loaded polymeric nanoparticles on the lipid profile and nitric oxide (NO)/reactive oxygen species (ROS) balance in the heart and aorta of adult male obese Zucker rats. The rats were divided into an untreated group, a group treated with empty nanoparticles, and groups treated with simvastatin-, coenzyme Q10 (CoQ10)-, or a combination of simvastatin- and CoQ10-loaded nanoparticles (SIMV+CoQ10). After 6 weeks, the lipid profile in the plasma and the concentration of conjugated dienes in the liver were determined. Nitric oxide synthase (NOS) activity, Akt, endothelial NOS (eNOS), phosphorylated eNOS (p-eNOS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and nuclear factor kappaB (NF-kappaB) protein expressions were measured in the heart and aorta. All simvastatin, CoQ10, and SIMV+CoQ10 treatments decreased plasma LDL levels, but only the combined SIMV+CoQ10 treatment increased NOS activity and the expression of Akt, eNOS, and p-eNOS in both the heart and the aorta. Interestingly, NADPH oxidase in the heart and NF-kappaB protein expression in the aorta were decreased by all treatments, including nanoparticles alone. In conclusion, only combined therapy with SIMV- and CoQ10-loaded nanoparticles increased NOS activity and upregulated the Akt-eNOS pathway in obese Zucker rats, which may represent a promising tool for the treatment of cardiometabolic diseases.     

Spatial Directional Radiance Caching

We present a new approach for accelerated global illumination computation in scenes with glossy surfaces. Our algorithm combines sparse illumination computation used in the radiance caching algorithm with BRDF importance sampling. To make this approach feasible, we extend the idea of lazy illumination evaluation, used in the caching approaches, from the spatial to the directional domain. Using importance sampling allows us to apply caching not only on low-gloss but also on shiny materials with high-frequency BRDFs, for which the radiance caching algorithm breaks down.     

Biomass ash-based mineral admixture prepared from municipal sewage sludge and its application in cement composites

Biomass as the biodegradable fraction of both agricultural products and industrial and municipal waste is currently a versatile energy resource. It can be stored and converted in practically any form of energy carrier and also into biochemicals and biomaterials from which, once they have been used, the energy content can be recovered to generate electricity, heat, or transport fuels. Moreover, the residues of its incineration can often be reused as pozzolanic additions to cement which can be considered as an environmentally friendly way of their disposal. In this paper, municipal sewage sludge with the organic carbon content of 27% was used for the preparation of biomass ash that should potentially find use as environmentally friendly mineral admixture to construction binders. Based on physical and chemical characterization of the raw material that showed a suitable chemical and phase composition, organic matter in a significant amount, and no thermal decomposition processes above 700 °C, biomass ash was produced. The biomass ash was obtained by incineration of sewage sludge at 700 °C, and mechanical activation contained 52% of amorphous phase which correlates with its good pozzolanic activity. The concentration of heavy metals, soluble chlorides, nitrates, and sulfates in biomass ash is found well below the standard permissible values. The composites prepared with a biomass ash dosage of 10, 20, and 30 wt% of Portland cement exhibited good functional properties. The increase in porosity up to 6% and decrease in compressive strength up to 3% were satisfactory. The results of leaching tests showed that composites with biomass ash contain only trace amounts of chlorides, nitrates, and sulfates. Apparently, the chlorides contained in biomass ash (0.7 mg/g) were immobilized in the cement matrix because the amounts of leached chlorides (0.04 wt%) were the same for all composites and well below the permissible limit for concrete. As revealed by the X-ray diffraction and thermogravimetric analyses, a significant decrease in portlandite content with increasing biomass ash content confirmed the pozzolanic reaction in biomass ash containing composite mixes. The environmental assessment showed a significant decrease in both carbon dioxide production and energy consumption with the increasing biomass ash content. For the composite with 30% biomass ash dosage, it was 21% of CO₂ and 11% of energy, as compared with the reference mix. The combination of good functional and environmental parameters of the analyzed composites makes good prerequisites for their application in construction industry. Taylor-made mineral admixture on biomass ash basis can find a broad use as eco-efficient admixture to cement- and lime-based binders.     

Shear flow effect on the crystalline forms in polyamide 6/montmorillonite nanocomposites

The influence of shear flow on the crystallization of polyamide 6/MMT nanocomposites prepared by melt intercalation process was investigated in detail by differential scanning calorimetry. The melted nanocomposites were controlled sheared in the steady and oscillatory shear flow, using a rotational rheometer, and cooled in an inert atmosphere. The effects of shear rate or frequency, clay concentration, and crystallization conditions on PA 6 crystalline phase development were studied. As expected, an opposite impact of shearing on γ‐phase formation in the nanocomposites and neat matrix was found. Surprisingly, a critical shear frequency for the onset of γ‐form crystallinity formation in the nanocomposites, increasing with the filler content as a consequence of polymer chains confinement within oriented clay platelets was found. At higher shear frequencies, the proportion of γ‐form in the nanocomposites increased dramatically with the clay concentration and reached 30–40%. The shear flow effects were influenced by cooling conditions, and more significant effect for rapidly cooled samples was observed. The isothermal crystallization at the solidification temperature 205°C reduced the γ‐form content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Signaling Involved in Hair Follicle Morphogenesis and Development

Hair follicle morphogenesis depends on Wnt, Shh, Notch, BMP and other signaling pathways interplay between epithelial and mesenchymal cells. The Wnt pathway plays an essential role during hair follicle induction, Shh is involved in morphogenesis and late stage differentiation, Notch signaling determines stem cell fate while BMP is involved in cellular differentiation. The Wnt pathway is considered to be the master regulator during hair follicle morphogenesis. Wnt signaling proceeds through EDA/EDAR/NF-κB signaling. NF-κB regulates the Wnt pathway and acts as a signal mediator by upregulating the expression of Shh ligand. Signal crosstalk between epithelial and mesenchymal cells takes place mainly through primary cilia. Primary cilia formation is initiated with epithelial laminin-511 interaction with dermal β-1 integrin, which also upregulates expression of downstream effectors of Shh pathway in dermal lineage. PDGF signal transduction essential for crosstalk is mediated through epithelial PDGF-A and PDGFRα expressed on the primary cilia. Dermal Shh and PDGF signaling up-regulates dermal noggin expression; noggin is a potent inhibitor of BMP signaling which helps in counteracting BMP mediated β-catenin inhibition. This interplay of signaling between the epithelial and dermal lineage helps in epithelial Shh signal amplification. The dermal Wnt pathway helps in upregulation of epithelial Notch expression. Dysregulation of these pathways leads to certain abnormalities and in some cases even tumor outgrowth.     

Cross-linked poly(ethylene vinyl acetate) (EVA)/low density polyethylene (LDPE)/metal hydroxides composites for wire and cable applications

Formulations of chemically cross-linked poly(ethylene vinyl acetate) (EVA) and low density polyethylene (LDPE) blends containing metal hydroxides flame retardants such as aluminum hydroxide (ATH) and magnesium hydroxide (MH) were prepared. Comparison of both type of metal hydroxides in respect of their influence on flammability as well as mechanical, thermal, and electrical properties of EVA/LDPE composites is presented. Most of the investigated properties are better for composites containing MH in comparison with composites containing ATH. Influence of various EVA/LDPE ratios on investigated properties is presented as well. Importance of improving compatibility using compatibilizers to improve some of the investigated properties is described. Polyethylene grafted with maleic anhydride (PEgMA) was found to be better compatibilizer for ATH than vinyl silanes.     

Alumina/MWCNTs composites by aqueous slip casting and pressureless sintering

Slip casting of stabilized aqueous suspensions followed by pressureless sintering was used for preparation of dense Al₂O₃/MWCNTs composites. The suspensions were stabilized by commercial polyelectrolyte dispersant Darvan C–N. In order to increase the stability, the pH value of the suspension was adjusted to ∼10. At this pH the highest ζ-potential values of the alumina powder and of the MWCNTs functionalised in boiling nitric acid were achieved. Two different agents, namely ammonium hydroxide and sodium hydroxide, were used for the pH adjustment. Their influence on the viscosity of suspensions and on consolidation and densification behaviour of the Al₂O₃/MWCNT composites was evaluated. The effect of ammonium hydroxide was more pronounced, as confirmed by lower viscosity of the suspension, higher sintered density, and fine-grained microstructure of the sintered composites. The Al₂O₃/t-MWCNTs composites with 0.1 wt% of the MWCNTs, with 99.9% relative density, the mean size of alumina grains ∼1 μm, and homogeneously distributed carbon nanotubes were prepared by the pressureless sintering at 1500 °C.