Nanoparticles in ambient air. measurement methods

Methods for the measurement of the parameters of aerosol particles with the use of an analyzer based on the differential mobility of nanoparticles and with a diffusion aerosol spectrometer are described and tested. A comparison of the results of measurements of the diameters of nanoparticles by the two methods is performed. Results of inter-laboratory comparisons of the analyzers based on the differential mobility of nanoparticles and studies of the electric motors of household appliances which are generators of the aerosols of nanoparticles with dimensions in the range 6–50 nm are presented.     

Relationships between environmental metrics and water temperature: a case study of Polish lowland rivers

The article presents relations between environmental metrics and water temperature in small Polish lowland rivers and describes their spatial temperature patterns. Water temperature data was obtained from measurements conducted on nine sites during summer of 2015 with the use of digital data loggers. Selected environmental metrics in the catchments areas were calculated and correlated with water temperature parameters. The results showed that water temperature patterns were generally similar across catchments, except for sites with strong human influence, which caused a decrease in the number and power of statistically significant relationships between environmental metrics and water temperature parameters. The best‐explained water temperature parameter was the minimum and mean daily range, while the best environmental predictors were the Strahler order, catchment area, mean catchment elevation and forested area. Most of the relations proved to be theoretically justified and could be used to further improve temperature monitoring studies and the management of water resources.     

Relaxation processes in hybrid organic-inorganic polymer nanosystems polymerized in situ

The relaxation processes of hybrid organic-inorganic polymer nanosystems (OIS) synthesized by joint polymerization of organic and inorganic components were studied using methods of differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and broadband dielectric relaxation spectroscopy (DRS). The organic component was a mixture of two products: high-molecular-weight macrodiisocyanate (MDI) with low reactivity and low-molecular-weight isocyanate-containing modifier poly(isocyanate) (PIC) with high reactivity. Sodium silicate (SS) was used as inorganic component. The structures of the OIS obtained were in the form of hybrids with covalently connected building blocks and interpenetrating networks: weakly cross-linked network MDI/SS and highly cross-linked network PIC/SS. Depending on the MDI/PIC ratio, one of the networks was prevailing and created a continuous structure with domains of second network.

PACS

61.25.hk; 82.35.Lr; 64.70.pj     

Discriminating native and plantation forests in a Landsat time-series for land use policy design

The Warren River Catchment of south-western Australia is an area of high biodiversity threatened by the loss of native vegetation and dryland salinity. Over the last 20 years, it has been the target of a series of policies that encourage conversion of agricultural land to plantation forest. Remote sensing has a key role in measuring trends in the area of plantation forest observed across the landscape and hence the effectiveness of policy initiatives. Despite its importance to land use policy, accurate data on historical land use and land cover (LULC) dynamics of two spectrally similar but ecologically distinct forest types – such as native forest and plantation forest – are not readily available for south-western Australia, largely due to prohibitive data delivery costs. However, we argue that regular low-cost monitoring of long-term change in the spatial distribution of plantation forest through remote sensing is a critical input into environmental policy for the catchment. To this end, a 35-year time-series of Landsat imagery was acquired, and three different classifiers were tested (Support Vector Machines – SVM; Random Forests – RF; and Classification and Regression Trees – CART) on spectral and textural indices applied to four spectral bands. The six major LULC classes considered were agriculture, water, native forest, sand dunes, plantation forest and harvested native forest. In classifying the imagery the SVM and RF outperformed the CART across all classes. However, the SVM classifier gave a slightly higher F-score for most individual classes than the RF. Eucalypt dominated plantation forest reaching full canopy cover was subject to the highest rates of misclassification inasmuch as it shares spectral properties with the Eucalypt dominant native forest. When applied to Landsat time-series imagery, SVM classifier combined with four bands held in common between the four Landsat sensors, and derived textures metrics are valuable in classifying plantation and native forest, particularly where these have a similar species composition. The differences in prediction accuracy when including additional Landsat bands were not statistically significant, as demonstrated by the McNemar test. Thus, we achieved a trade-off in reducing processing time without significantly impacting on classification accuracy (≥86%). The relatively high accuracy of the proposed method enables the effects of past policy initiatives to be observed, and hence the efficient design of environmental and conservation policy in the future.     

Feasibility in assessing the dipped rail joint defects through dynamic response of heavy haul locomotive

The feasibility of monitoring the dipped rail joint defects has been theoretically investigated by simulating a locomotive-mounted acceleration system negotiating several types of dipped rail defects. Initially, a comprehensive locomotive-track model was developed using the multi-body dynamics approach. In this model, the locomotive car-body, bogie frames, wheelsets and driving motors are considered as rigid bodies; track modelling was also taken into account. A quantitative relationship between the characteristics (peak–peak values) of the axle box accelerations and the rail defects was determined through simulations. Therefore, the proposed approach, which combines defect analysis and comparisons with theoretical results, will enhance the ability for long-term monitoring and assessment of track systems and provides more informed preventative track maintenance strategies.

     

Open Quantum Systems Coupled to Time-Dependent Classical Environments

We investigate the behavior of open quantum systems interacting with classical time-dependent environments. As a simple example, we employ a two-level quantum system, and a thermodynamic oscillator serves as an environment. We analyze how the relationship between parameters of the classical environment and the quantum subsystem changes the evolution. Using the nonlinear thermodynamic master equation, we demonstrate how the energy of the quantum system evolves in time and how feedback effects from a quantum to a classical system influences the dynamics.     

LDPE/clay/carvacrol nanocomposites with prolonged antimicrobial activity

Over the past decade there is an immense effort to develop antimicrobial packaging systems, which incorporates natural biopreservatives, such as essential oils (EOs). The highly volatile nature of EOs, which is advantageous for their efficient diffusion and mode of action, presents a major obstacle for their incorporation with polyolefins via conventional high‐temperature melt compounding and processing. This study presents a new approach to use organo‐modified montmorillonite (MMT) clays, as active carriers for carvacrol (used as a model EO), aiming to minimize its loss throughout the polymer compounding. Different MMT clays are pretreated with carvacrol, resulting in the oil molecules intercalation in between the clay galleries and enhanced carvacrol thermal stability. These hybrids are incorporated within low‐density polyethylene (LDPE) and the resulting films are characterized in terms of their nanostructure, thermal properties, and antimicrobial activity. The LDPE/(clay/carvacrol) nanocomposites exhibit excellent and prolonged antimicrobial activity against E. coli bacteria, while LDPE/carvacrol films loss their antimicrobial functions within several days. The superior antimicrobial behavior is ascribed to the significantly higher carvacrol content and its enhanced thermal stability within the films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41261.     

2D Oxide Nanomaterials to Address the Energy Transition and Catalysis

2D oxide nanomaterials constitute a broad range of materials, with a wide array of current and potential applications, particularly in the fields of energy storage and catalysis for sustainable energy production. Despite the many similarities in structure, composition, and synthetic methods and uses, the current literature on layered oxides is diverse and disconnected. A number of reviews can be found in the literature, but they are mostly focused on one of the particular subclasses of 2D oxides. This review attempts to bridge the knowledge gap between individual layered oxide types by summarizing recent developments in all important 2D oxide systems including supported ultrathin oxide films, layered clays and double hydroxides, layered perovskites, and novel 2D‐zeolite‐based materials. Particular attention is paid to the underlying similarities and differences between the various materials, and the subsequent challenges faced by each research community. The potential of layered oxides toward future applications is critically evaluated, especially in the areas of electrocatalysis and photocatalysis, biomass conversion, and fine chemical synthesis. Attention is also paid to corresponding novel 3D materials that can be obtained via sophisticated engineering of 2D oxides.