Abstract: The interaction between electrons and plasmons in trilayer graphene is investigated within the Overhauser approach resulting in the “plasmaron” quasiparticle. This interaction is cast into a field theoretical problem, and its effect on the energy spectrum is calculated using improved Wigner-Brillouin perturbation theory. The plasmaron spectrum is shifted with respect to the bare electron spectrum by ΔE(k)∼150−200meV for ABC stacked trilayer graphene and for ABA trilayer graphene by ΔE(k)∼30−150 meV[ ΔE(k) ∼1 −5meV] for the hyperbolic (linear) part of the spectrum. The shift in general increases with the electron concentration and electron momentum. The dispersion of plasmarons is more pronounced in ABC stacked than in ABA stacked trilayer graphene, because of the different energy band structure and their different plasmon dispersion.

Abstract: Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and
automobile industries. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize
their use efficiency, however, very challenging. Here we report a practical synthesis for isolated single Pt
atoms anchored to graphene nanosheet using the atomic layer deposition (ALD) technique. ALD offers the
capability of precise control of catalyst size span from single atom, subnanometer cluster to nanoparticle.
The single-atom catalysts exhibit significantly improved catalytic activity (up to 10 times) over that of the
state-of-the-art commercial Pt/C catalyst. X-ray absorption fine structure (XAFS) analyses reveal that the
low-coordination and partially unoccupied densities of states of 5d orbital of Pt atoms are responsible for the
excellent performance. This work is anticipated to form the basis for the exploration of a next generation of
highly efficient single-atom catalysts for various applications.

Abstract: A new method is developed for synthesizing Ti4O7 supported Ru@Pt core–shell catalyst (Ru@Pt/Ti4O7) through pyrolysis followed by microwave irradiation. The purpose is to improve the Ru durability of PtRu from core–shell structure and strong bonding to Ti4O7 oxide. In this method, the first step is to co-reduce the mixture of ruthenium precursor and TiO2 in a H2 reducing atmosphere under heat-treatment to obtain a Ru core on Ti4O7 support, and the second step is to create a shell of platinum via microwave irradiation. Energy dispersive X-ray spectrometry, X-ray Diffraction, High-resolution Scanning Transmission Electron Microscopy with the high-angle annular dark-field method and Electron Energy-Loss Spectroscopy are used to demonstrate that this catalyst with larger particles has a core–shell structure with a Ru core and a Pt shell. Electrochemical measurements show Ru@Pt/Ti4O7 catalyst has a higher CO-tolerance capability than that of PtRu/C alloy catalyst.

Abstract: Endocrine disruptors (EDCs) are environmental pollutants that, once incorporated into an organism, affect the hormonal balance of humans and various species. Its presence in environment is of great importance in water quality related questions. The proposed method describes the development of an accurate, sensitive and selective sensor for the detection of bisphenol-A (BPA) and its treatment by green technology. A fullerene (C60) fabricated electrochemical sensor was developed for the ultrasensitive detection of BPA. The homemade sensor was characterized by scanning electron microscopy, electrochemical impedance spectroscopy and chronocoulometry. The influence of measuring parameters such as pH and C60 loading on the analytical performance of the sensor was evaluated. Various kinetic parameters such as electron transfer number (n); charge transfer coefficient (α); electrode surface area (A) and diffusion coefficient (D) were also calculated. Under the optimal conditions, the oxidation peak current was linear over the concentration range of 74 nM to 0.23 μM with the detection limit (LOD) of 3.7 nM. The fabricated sensor was successfully applied to the determination of BPA in wastewater samples and it has promising analytical applications for the direct determination of BPA at trace level.

Abstract: The measurement of the ratio of stable isotopes of carbon (13C/12C expressed as a δ13C) in the individual components of a sample may be used as a means to identify the origin of these components. This article reviews the approaches and reports on the successes and failures of source identification and apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) with the use of compound-specific isotope analysis (CSIA). One of the conditions for a precise and accurate analysis of isotope ratios with the use of GC-C-IRMS is the need for well separated peaks, with no co-elutions, and reduced unresolved complex mixture (UCM). Additionally, special care needs to be taken for an investigation of possible isotope fractionation effects introduced during the analytical treatment of samples. With the above-mentioned problems in mind, this review discusses in detail and compares current laboratory methodologies, mainly in the extraction and subsequent clean-up techniques used for environmental samples (air particulate matter, soil and sediments). Sampling strategies, the use of isotopic internal standards and the ranges for precision and accuracy are also reported and discussed.

Abstract: The presence of persistent organic pollutants in Tanzanian environment is not well monitored despite the existing pollution potential from a number of sources. In this study, we investigated for the first time, the concentration profiles of different organohalogen compounds such as organochlorine pesticide residues (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in environmental samples (water and sediments) from the Pangani river basin (PRB). The PRB is one of the largest drainage basins in Tanzania, with its watershed exposed to multiple input sources of trace organic contaminants. Surface water and sediments were sampled from 12 representative stations of diverse characteristics and land-use practices, in three distinct seasons, and extracted by liquidliquid and Soxhlet extraction methods, respectively. Water samples were analyzed by GC-ECD for OCPs only, while sediment samples were analyzed for OCPs, PCBs and PBDEs by GC/MS. Seven compounds, dominated by HCH isomers (5104460 pg/L) and DDT analogs (1601460 pg/L),were detected in the water samples. These concentrations are far below the WHO guidelines for drinking water quality. A total of 42 compounds (8 OCPs, 28 PCB congeners and 6 PBDE congeners) were detected in the sediment samples. Their respective total concentration ranges were 24510,230; 35711,000 and 382175 pg/g dry weight. The spatial distribution patterns and Hierarchical Cluster Analysis reflected the impact of historical agricultural usage in sugarcane plantations (OCPs), and urbanization (PCBs and PBDEs). Risk assessment using sediment quality guidelines indicated no ecotoxicological risks. The results we have found provide preliminary data on levels of the organic contaminants in Pangani river basin as a new insight on the environmental quality of the area.

Abstract: We present here data of mineral dust variability retrieved from an ice core of the central West Antarctic, spanning the last five decades. Main evidence provided by the geochemical analysis is that northerly air mass incursions to the coring site, tracked by insoluble dust microparticles, have declined over the past 50 yr. This result contrasts with dust records from ice cores reported to the coastal West Antarctic that show increases since mid-20th century. We attribute this difference to regional climatic changes due to the ozone depletion and its implications to westerly winds. We found that the diameters of insoluble microparticles in the central West Antarctica ice core are significantly correlated with cyclone depth (energy) and wind intensity around Antarctica.

Abstract: Diesel soot emissions deteriorate the appearance of architectural building materials by soot fouling. This soot deposition devalue the aesthetic value of the building. A solution to counteract this problem is applying titanium dioxide on building materials. TiO2 can provide air-purifying and self-cleaning properties due to its photocatalytic activity. In literature, photocatalytic soot oxidation is observed on glass or silicon substrates. However, degradation of soot by photocatalysis was not yet investigated on cementitious samples (mortar, concrete) although it is one of the most frequently used building materials. In this study, photocatalytic soot oxidation by means of TiO2 coated cementitious samples is addressed. The soot removal capacity of four types of TiO2 layers, coated on mortar samples, is evaluated by means of two detection methods. The first method is based on colorimetric measurements, while the second method uses digital image processing to calculate the area of soot coverage. The experimental data revealed that cementitious materials coated with commercially available TiO2 exhibited self-cleaning properties as it was found that all coated samples were able to remove soot. The P25 coating gave the best soot degradation performance, while the Eoxolit product showed the slowest soot degradation rate. In addition, gas chromatography measurements in a closed chamber experiment with P25 confirmed that complete mineralization of about 60% of the soot was obtained within 24 hours since CO2 was the sole observed oxidation product. Due to its realistic approach, this study proves that photocatalytic soot removal on TiO2 coated cementitious surfaces is possible in practice, which is an important step towards the practical application of self-cleaning building materials.

Abstract: We present a novel manufacture route for silicatitania photocatalysts using the diatom microalga Pinnularia sp. Diatoms self-assemble into porous silica cell walls, called frustules, with periodic micro-, meso- and macroscale features. This unique hierarchical porous structure of the diatom frustule is used as a biotemplate to incorporate titania by a solgel methodology. Important material characteristics of the modified diatom frustules under study are morphology, crystallinity, surface area, pore size and optical properties. The produced biosilicatitania material is evaluated towards photocatalytic activity for NOx abatement under UV radiation. This research is the first step to obtain sustainable, well-immobilised silicatitania photocatalysts using diatoms.

Abstract: Soils are complex mixtures of organic, inorganic materials, and metal compounds from anthropogenic sources. In order to identify the pollution sources, their magnitude and development, several X-ray analytical methods were applied in this study. The concentrations of 16 elements were determined in all the soil samples using energy dispersive X-ray fluorescence spectrometry. Soils of unknown origin were observed by scanning electron microscopy equipped with a Si(Li) X-ray detector using Monte Carlo simulation approach. The mineralogical analyses were carried out using X-ray diffraction spectrometry. Due to the correlations between heavy metals and oxide compounds, the samples were analyzed also by electron probe microanalyzer (EPMA) in order to have information about their oxide contents. On the other hand, soil pH and salinity levels were identified owing to their influence between heavy metal and soil-surface chemistry. Moreover, the geoaccumulation index (I geo) enables the assessment of contamination by comparing current and pre-industrial concentrations.

Abstract: The assessment of damage to indoor cultural heritage, in particular by pollutants, is nowadays a major and growing concern for curators and conservators. Nevertheless, although many museums have been widely investigated in Europe, the effects of particulate matter and gaseous pollutants in museums under tropical and subtropical climates and with different economic realities are still unclear. An important portion of the world's cultural heritage is currently in tropical countries where both human and financial resources for preserving museum collections are limited. Hence, our aim is to assess the damage that can be caused to the artwork by pollution in hot and humid environments, where air quality and microclimatic condition differences can cause deterioration. As a case study, particulate matter as well as gases were collected at the Oscar Niemeyer Museum (MON) in Curitiba, Brazil, where large modern and contemporary works of art are displayed. NO2, SO2, O3, Acetic Acid, Formic Acids and BTEX, in the ambient air, were sampled by means of passive diffusive sampling and their concentrations were determined by IC or GCMS. The particulate matter was collected in bulk form and analyzed with the use of energy dispersive X-ray fluorescence and aethalometer. The chemical compositions of individual particles were quantitatively elucidated, including low-Z components like C, N and O, as well as higher-Z elements, using automated electron probe microanalysis. The gaseous and particulate matter levels were then compared with the concentrations obtained for the same pollutants in other museums, located in places with different climates, and with some reference values provided by international cultural heritage conservation centers. Results are interpreted separately and as a whole with the specific aim of identifying compounds that could contribute to the chemical reactions taking place on the surfaces of artifacts and which could potentially cause irreversible damage to the artworks.