Investigating the role of microwave thermal and non-thermal effects on WO3-graphene oxide composite synthesis.

The effects of microwave-assisted synthesis on the morphology and crystalline structure of WO3-graphene oxide (GO) composites have been investigated. Using two different microwave reactors, evidence supports that thermal and non-thermal effects significantly influence the properties of the synthesized materials. The findings reveal that the microwave cavity geometry affects how the microwaves are "delivered" to the reactional cavity as a function of time; it also orientates the growth process of the WO3 particles. Consequently, the crystalline structure and morphology are affected. As a result, the WO3-GO composites produced using a CEM reactor exhibit a rounded shape and hexagonal phase of WO3, besides enhanced reduction of GO. Whereas the composites made using an Anton-Paar reactor are composed of sheets and flowers of WO3 with hexagonal, triclinic and/or WO3 hydrate structures and cause a lower reduction on the GO.

Amyloid-like Self-Assembly of a Hydrophobic Cell-Penetrating Peptide and Its Use as a Carrier for Nucleic Acids.

Cell-penetrating peptides (CPPs) are a topical subject potentially exploitable for creating nanotherapeutics for the delivery of bioactive loads. These compounds are often classified into three major categories according to their physicochemical characteristics: cationic, amphiphilic, and hydrophobic. Among them, the group of hydrophobic CPPs has received increasing attention in recent years due to toxicity concerns posed by highly cationic CPPs. The hexapeptide PFVYLI (P, proline; F, phenylalanine; V, valine; Y, tyrosine; L, leucine; and I, isoleucine), a fragment derived from the C-terminal portion of α1-antitrypsin, is a prototypal example of hydrophobic CPP. This sequence shows reduced cytotoxicity and a capacity of nuclear localization, and its small size readily hints at its suitability as a building block to construct nanostructured materials. In this study, we examine the self-assembling properties of PFVYLI and investigate its ability to form noncovalent complexes with nucleic acids. By using a combination of biophysical tools including synchrotron small-angle X-ray scattering and atomic force microscopy-based infrared spectroscopy, we discovered that this CPP self-assembles into discrete nanofibrils with remarkable amyloidogenic features. Over the course of days, these fibrils coalesce into rodlike crystals that easily reach the micrometer range. Despite lacking cationic residues in the composition, PFVYLI forms noncovalent complexes with nucleic acids that retain ß-sheet pairing found in amyloid aggregates. In vitro vectorization experiments performed with double-stranded DNA fragments indicate that complexes promote the internalization of nucleic acids, revealing that tropism toward cell membranes is preserved upon complexation. On the other hand, transfection assays with splice-correction oligonucleotides (SCOs) for luciferase expression show limited bioactivity across a narrow concentration window, suggesting that the propensity to form amyloidogenic aggregates may trigger endosomal entrapment. We anticipate that the findings presented here open perspectives for using this archetypical hydrophobic CPP in the fabrication of nanostructured scaffolds, which potentially integrate properties of amyloids and translocation capabilities of CPPs.

Influence of Preparation Methodology on the Photocatalytic Activity of Nitrogen Doped Titanate and TiO2 Nanotubes.

Titanate and TiO2 nanotubes (TiNTs and TiO2NTs) are known as good photocatalysts under UV light irradiation, due to their high band gap energy. The nitrogen-doping process is one of the most studied methods to make these materials sensitive to visible light. However, most of these studies are focused on how calcination temperature affects the crystalline structure and, consequently, the photocatalytic efficiency, and few are investigated about the choice of the doping method. Here we report the synthesis of nitrogen-doped TiNTs and TiO2NTs (NTiNTs and NTiO2NT) through two different methods, and the comparison of the obtained materials properties. The photocatalytic efficiency was evaluated under visible light and correlated to the nature of nitrogen doping, which is a consequence of the doping method chosen. We found that the NTiNT's lamellar structure and its more negative zeta potential shall facilitate its interaction with the dye to be degraded. Moreover, the adsorbed nitrogen plays an important role over the degradation process.

Nocturnal accumulation of CO2 underneath a tropical forest canopy along a topographical gradient.

Flux measurements of carbon dioxide and water vapor above tropical rain forests are often difficult to interpret because the terrain is usually complex. This complexity induces heterogeneity in the surface but also affects lateral movement of carbon dioxide (CO2) not readily detected by the eddy covariance systems. This study describes such variability using measurements of CO2 along vertical profiles and along a toposequence in a tropical rain forest near Manaus, Brazil. Seasonal and diurnal variation was recorded, with atmospheric CO2 concentration maxima around dawn, generally higher CO2 build-up in the dry season and stronger daytime CO2 drawdown in the wet season. This variation was reflected all along the toposequence, but the slope and valley bottom accumulated clearly more CO2 than the plateaus, depending on atmospheric stability. Particularly during stable nights, accumulation was along lines of equal altitude, suggesting that large amounts of CO2 are stored in the valleys of the landscape. Flushing of this store only occurs during mid-morning, when stored CO2 may well be partly transported back to the plateaus. It is clear that, for proper interpretation of tower fluxes in such complex and actively respiring terrain, the horizontal variability of storage needs to be taken into account not only during the night but also during the mornings.

Enhanced inflammatory response following coronary stent implantation in stable angina patients.

BACKGROUND: Percutaneous coronary intervention (PCI) is associated with an increase in inflammatory activity. However, little is known about the association between the inflammatory response post-PCI and plaque morphology. The objective of this study was to characterize the inflammatory response following coronary stent implantation (CSI) of stable atherosclerotic plaques, according to plaque morphology. METHODS: The study population consisted of 62 patients with stable angina that had an elective indication of CSI. Immediately before CSI, the patients underwent intravascular ultrasound (IVUS) for determination of the predominant plaque morphology of the target lesion: calcified (C, n=15), fibrocalcified (FC, n=16), fibrolipidic (FL, n=16), or lipidic (L, n=15). Angiographic lesion types were also determined. Coronary sinus samples were collected at baseline (BL) and 15 min after CSI for measuring inflammatory mediators (IM): interleukin-6 (IL-6, in pg/ml), tumoral necrosis factor-alpha (TNF, in pg/ml), interferon-gamma (IFN, in IU/ml), and neopterin (N, in ng/ml). RESULTS: BL IL-6, TNF, IFN, and N were, respectively, for C plaques (mean+/-S.D.): 1.3+/-3.0, 8.0+/-3.5, 0.1+/-0.2, and 3.2+/-0.8; for FC plaques: 6.7+/-3.3, 1.9+/-2.0, 0.1+/-0.1, and 3.8+/-2.0; for FL plaques: 0.7+/-0.9, 8.7+/-4.3, 0.1+/-0.2, and 4.0+/-2.4; and, for L plaques: 1.9+/-2.8, 0.9+/-1.4, 0.0+/-0.1, and 5.2+/-3.3. After 15 min of CSI, percentual changes of IL-6, TNF, IFN, and N, respectively, were for C plaques: 43.8+/-19.6%, 7.7+/-5.5%, -7.5+/-5.3%, and -20.0+/-11.2%; for FC plaques: 7.7+/-5.5%, 168.4+/-56.9%, 311.1+/-159.9%, and 0%; for FL plaques: 147.5+/-16.1%*, 714.3+/-34.4%*, 116.1+/-9.9%*, and 3000.0+/-230.0%*; and, for L plaques: 147.7+/-14.4%*, 140.3+/-15.0%*, 131.6+/-11.9%*, and 2300.0+/-25.9%*. Moreover, B1 (n=28) and B2 (n=32) predominated and resulted in significant changes only for IL-6 and IFN, respectively. *P<0.05: 15 min vs BL. CONCLUSIONS: These data suggest that stable angina patients with predominant lipidic (L and FL) plaques present a greater inflammatory response after CSI in than those with predominant calcified (C and FC) plaques.