Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O₂-free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production.In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide.     

Differentiating N-terminal aspartic and isoaspartic acid residues in peptides

Formation of isoaspartic acid (isoAsp) is a common modification of aspartic acid (Asp) or asparagine (Asn) residue in proteins. Differentiation of isoAsp and Asp residues is a challenging task owing to their similar properties and identical molecular mass. It was recently shown that they can be differentiated using ion-electron or ion-ion interaction fragmentation methods (ExD) because these methods provide diagnostic fragments c + 57 and z(?) - 57 specific to the isoAsp residue. To date, however, the presence of such fragments has not been explored on peptides with an N-terminal isoAsp residue. To address this question, several N-terminal isoAsp-containing peptides were analyzed using ExD methods alone or combined with chromatography. A diagnostic fragment [M + 2H - 74](+?) was observed for the doubly charged precursor ions with N-terminal isoAsp residues. For some peptides, identification of the N-terminal isoAsp residue was challenging because of the low diagnostic ion peak intensity and the presence of interfering peaks. Supplemental activation was used to improve diagnostic ion detection. Further, N-terminal acetylation was offered as a means to overcome the interference problem by shifting the diagnostic fragment peak to [M + 2H - 116](+?).     

Nanocarriers for Biomedicine: From Lipid Formulations to Inorganic and Hybrid Nanoparticles

Encapsulation of cargoes in nanocontainers is widely used in different fields to solve the problems of their solubility, homogeneity, stability, protection from unwanted chemical and biological destructive effects, and functional activity improvement. This approach is of special importance in biomedicine, since this makes it possible to reduce the limitations of drug delivery related to the toxicity and side effects of therapeutics, their low bioavailability and biocompatibility. This review highlights current progress in the use of lipid systems to deliver active substances to the human body. Various lipid compositions modified with amphiphilic open-chain and macrocyclic compounds, peptide molecules and alternative target ligands are discussed. Liposome modification also evolves by creating new hybrid structures consisting of organic and inorganic parts. Such nanohybrid platforms include cerasomes, which are considered as alternative nanocarriers allowing to reduce inherent limitations of lipid nanoparticles. Compositions based on mesoporous silica are beginning to acquire no less relevance due to their unique features, such as advanced porous properties, well-proven drug delivery efficiency and their versatility for creating highly efficient nanomaterials. The types of silica nanoparticles, their efficacy in biomedical applications and hybrid inorganic-polymer platforms are the subject of discussion in this review, with current challenges emphasized.     

Peptide Integrated Optics

Bio‐nanophotonics is a wide field in which advanced optical materials, biomedicine, fundamental optics, and nanotechnology are combined and result in the development of biomedical optical chips. Silk fibers or synthetic bioabsorbable polymers are the main light‐guiding components. In this work, an advanced concept of integrated bio‐optics is proposed, which is based on bioinspired peptide optical materials exhibiting wide optical transparency, nonlinear and electrooptical properties, and effective passive and active waveguiding. Developed new technology combining bottom‐up controlled deposition of peptide planar wafers of a large area and top‐down focus ion beam lithography provides direct fabrication of peptide optical integrated circuits. Finding a deep modification of peptide optical properties by reconformation of biological secondary structure from native phase to β‐sheet architecture is followed by the appearance of visible fluorescence and unexpected transition from a native passive optical waveguiding to an active one. Original biocompatibility, switchable regimes of waveguiding, and multifunctional nonlinear optical properties make these new peptide planar optical materials attractive for application in emerging technology of lab‐on‐biochips, combining biomedical photonic and electronic circuits toward medical diagnosis, light‐activated therapy, and health monitoring.     

Glial-Neuronal Interactions in Pathogenesis and Treatment of Spinal Cord Injury

Traumatic spinal cord injury (SCI) elicits an acute inflammatory response which comprises numerous cell populations. It is driven by the immediate response of macrophages and microglia, which triggers activation of genes responsible for the dysregulated microenvironment within the lesion site and in the spinal cord parenchyma immediately adjacent to the lesion. Recently published data indicate that microglia induces astrocyte activation and determines the fate of astrocytes. Conversely, astrocytes have the potency to trigger microglial activation and control their cellular functions. Here we review current information about the release of diverse signaling molecules (pro-inflammatory vs. anti-inflammatory) in individual cell phenotypes (microglia, astrocytes, blood inflammatory cells) in acute and subacute SCI stages, and how they contribute to delayed neuronal death in the surrounding spinal cord tissue which is spared and functional but reactive. In addition, temporal correlation in progressive degeneration of neurons and astrocytes and their functional interactions after SCI are discussed. Finally, the review highlights the time-dependent transformation of reactive microglia and astrocytes into their neuroprotective phenotypes (M2a, M2c and A2) which are crucial for spontaneous post-SCI locomotor recovery. We also provide suggestions on how to modulate the inflammation and discuss key therapeutic approaches leading to better functional outcome after SCI.     

Pt nanoparticles sputter-deposited on TiO2/MWCNT composites prepared by atomic layer deposition: Improved electrocatalytic activity towards the oxygen reduction reaction and durability in acid media

Acid-treated multi-walled carbon nanotubes (MWCNTs) were decorated with TiO₂ using the atomic layer deposition (ALD) technique followed by uniform distribution of platinum nanoparticles (PtNPs) through magnetron sputtering. Surface analyses were performed by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical decontamination and characterization of the Pt-TiO₂/MWCNT electrodes were carried out by CO stripping followed by cyclic voltammetry in acid media. The oxygen reduction reaction (ORR) was studied in O₂-saturated 0.05 M H₂SO₄ solution using the rotating disk electrode (RDE) method. Durability of the prepared catalysts was examined by repetitive potential cycling. Electrochemical data obtained was analyzed and compared to that of the commercial Pt/C catalyst. It was revealed that the Pt-TiO₂/MWCNT catalysts possess higher ORR activity and better durability as compared to that of the commercial Pt/C.     

Trauma/grief-focused group psychotherapy: School-based postwar intervention with traumatized Bosnian adolescents.

Results of a preliminary effectiveness evaluation of a school-based postwar program for war-exposed Bosnian adolescents are described. The evaluation centered on a manualized trauma/grief-focused group psychotherapy protocol for war-traumatized adolescents based on 5 therapeutic foci: traumatic experiences, trauma and loss reminders, postwar adversities, bereavement and the interplay of trauma and grief, and developmental impact. Fifty-five secondary school students (81% girls; age range?=?15–19 years, M?=?16.81) from 10 Bosnian schools participated in the evaluation. Students completed pregroup and postgroup self-report measures of posttraumatic stress, depression, and grief symptoms and postgroup measures of psychosocial adaptation and group satisfaction. The evaluation yielded preliminary but promising results, including reduced psychological distress and positive associations between distress reduction and psychosocial adaptation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanical properties and water vapor permeability of starch/montmorillonite nanocomposites

Results of an investigation into an unmodified‐montmorillonite (MMT)‐filled nanocomposite based on plasticized starch are reported. Data on the influence of MMT content on the tensile mechanical properties of the material are presented. Particular attention is given to the water vapor permeability of the nanocomposite. It is found that the resistance to water permeation of plasticized starch can be improved considerably by introducing a rather small amount of the filler into it. Data on the influence of MMT content on the coefficients of moisture diffusion, solubility, and permeability are reported. Also, a simple method for determining the effect of irregularly oriented platelike filler particles on the permeability of the composite material is suggested. The calculation results are compared with experimental data. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers