Organic Contaminants and Interactions with Micro- and Nano-Plastics in the Aqueous Environment: Review of Analytical Methods

Micro- and nanoplastic particles are increasingly seen not only as contaminants themselves, but also as potential vectors for trace organic chemicals (TOrCs) that might sorb onto these particles. An analysis of the sorbed TOrCs can either be performed directly from the particle or TOrCs can be extracted from the particle with a solvent. Another possibility is to analyze the remaining concentration in the aqueous phase by a differential approach. In this review, the focus is on analytical methods that are suitable for identifying and quantifying sorbed TOrCs on micro- and nano-plastics. Specific gas chromatography (GC), liquid chromatography (LC) and ultraviolet-visible spectroscopy (UV-VIS) methods are considered. The respective advantages of each method are explained in detail. In addition, influencing factors for sorption in the first place are being discussed including particle size and shape (especially micro and nanoparticles) and the type of polymer, as well as methods for determining sorption kinetics. Since the particles are not present in the environment in a virgin state, the influence of aging on sorption is also considered.

Minimal Invasive Diagnostic Capabilities and Effectiveness of CFRP-Patches Repairs in Long-Term Operated Metals

The paper deals with the subject of diagnostics and the quick repairs of long-term operated metallic materials. Special attention was paid to historical materials, where the structure (e.g., puddle iron) is different from modern structural steels. In such materials, the processes of microstructural degradation occur as a result of several decades of exposure, which could overpass 100 years. In some cases, their intensity can be potentially catastrophic. For this reason, the search for minimally invasive diagnostic methods is ongoing. In this paper, corrosion and fracture toughness tests were conducted, and the results of these studies were presented for two material states: post-operated and normalized (as a state “restoring” virgin state). Moreover, through the use of modern numerical methods, composite crack-resistant patches have been designed to reduce the stress intensity factors under cyclic loads. As a result, fatigue lifetime was extended (propagation phase) by more than 300%.

Producing and Measuring the 3rd Body Layer

Decades of measuring friction conditions at the wheel-rail interface have resulted in widely varying answers produced by different measurement methods and devices. This variation is a result of many factors, some of which are difficult to quantify and control, especially under field conditions. One of these variables is the presence of an unknown 3rd body layer material, whose accumulation on the wheel and rail surfaces affect the value of independent tests performed to quantify the nominal state of wheel on rail in actual operating conditions. This paper describes a series of tests undertaken to understand the creation of the 3rd body layer from the starting point of clean wheel and rail surfaces and how that can lead to new standard practices for field testing. A 2 × 2 matrix of wheel and rail conditions is defined to help formalize the discussion of the production and measurement of the 3rd body layer. Case 1 is the nominal virgin state of the two materials. This is actually fairly hard to produce. Almost any process and/or handling will leave some films on both surfaces. Lab tests typically start in this state after cleaning/degreasing the surfaces following machining or sanding. Cases 2 and 3 are potentially the same (clean wheel or rail), however, the more likely case is Case 2 where some existing location on actual track is chosen to determine its current state, thus the use of a Tribometer using a clean wheel. Case 4 represents the nominal state of most track with passing vehicles where the current environmental/ambient conditions encourage a particular set of 3rd body wear products. This formalization helps reveal the prior common practices that have produced assumptions of what is the ‘correct’ value and how that has created a bias in one’s thinking of what really exists in normal revenue service. This issue is particularly consequential in attempting to quantify the benefit of the friction modifiers that are being adopted across the railroad industry.

Estimation of the radiant performance of flame-retardant fabrics considering thermal degradation effect

Specially designed thermal protective clothing is used by firefighters and furnace operators for safety against intense heat flux exposures. Radiative transfer becomes the main heat transfer mode under such high temperature conditions. This work dealt with the effects of thermal degradation on the radiant protective performance and radiative properties of Polysulfonamide and Nomex IIIA fabrics at virgin state and pyrolyzed state, respectively. Simultaneously, the thermal stability and flame retardancy of both fabrics were compared by using thermogravimetry, vertical burning test, and limit oxygen index methods. The obtained results of thermal degradation effect on radiative properties demonstrated that both of the reflectance and transmittance of the two kinds of fabrics at virgin condition are higher than those at pyrolyzed state. On the other hand, the radiant protective performance values of both fabrics at charred condition were lower as compared to those at virgin state. This study will be helpful to estimate the continuing performance of firefighters’ protective fabrics after thermal exposures during firefighting operations.

Floristic composition of the kaan forests of Sagar Taluk: sacred landscape in the central Western Ghats, Karnataka, India

In the Malnad region of the central Western Ghats, Karnataka, ethnic people conserve village forests called kaan forests as the abode of sylvan deities. Ethnic taboos have kept kaan forests in a virgin state over the course of centuries. In recent times, the strong taboo around these kaan forests has lessened, and the withdrawal of managing rights of kaans has affected valued species. Of 103 kaan forests (totalling 5,254 ha) in the region, 24 (= 12 ha) well-managed kaan forests were inventoried floristically during 2008 to 2009. The results provided identification of a total of 303 species in 237 genera and 79 diverse families. Of these, 34 species belong to rare, endangered, or threatened categories 116 were endemics, and 150 were evergreen species. kaan forests are still essentially of climax character, and are the abode of ecologically sensitive plant species. Affording more powers to the local communities in protecting the local biodiversity would be more effective in conserving them.

Composition, Temperature and Frequency Dependent Magnetic, Dielectric and Electrical Properties of Magnesium-Zinc Ferrites

Polycrystalline spinel MgxZn0.3Cu0.7-2xFe2+xO4, where x = 0.10, 0.20, 0.25, 0.30 and 0.35 ferrites (hereafter abbreviated as Mg-Zn) have been prepared by conventional double sintering technique. The samples were sintered at 1250°C in air for 6 hours. Measurements have been done at temperature and frequency ranges of 0 - 350°C and 0 - 500 kHz, respectively. In this work, some extrinsic magnetic properties such as Curie temperature, initial permeability, loss factor, quality factor, dielectric constant and resistivity of the samples have been studied. The Curie temperature and loss tangent of the samples decreased with increase in Cu-content whereas permeability, Qfactor, resistivity and dielectric constant have been noticed to be increased with the increase in Cucontent. The decrease in Curie temperature related to fact of weakening the strength of exchange AB interaction. Maxwell-Wagner type of interfacial polarization might have found correlated with the normal dielectric behavior of the samples, however no relaxation peaks were observed in the dielectric dispersion curves of the Mg-Zn samples in virgin state or doped state. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12963 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 199-212, 2012