SECM Study of Effect of Chromium Content on the Localized Corrosion Behavior of Low-Alloy Steels in Chloride Environment

This paper investigates the effect of chromium (Cr) content (0, 1, 3 and 5% Cr) in epoxy-coated alloy steel against corrosion using in situ electrochemical techniques such as EIS and SECM in a 3% NaCl solution. The EIS results revealed that the epoxy-coated Cr steel exhibited higher impedance values than carbon steel, which is attributed to the greater resistance of Cr steel toward corrosion. Based on the cyclic voltammogram results, the tip potentials were set at ?0.7, 0.04 and 0.60 V for determining the concentration of dissolved oxygen at cathodic region, and oxidation of Cr²⁺ and Fe²⁺ at anodic region, respectively. The SECM measurements showed that, the tip current in the anodic region has decreased with increase in Cr content of the sample, which indicates that the oxidation of Fe²⁺ and Cr²⁺ decreases (corrosion is reduced) with the increase in Cr content of the steel. Besides, 5% Cr steel can maintain the highest corrosion resistance, and 1 and 3% Cr steels have higher corrosion resistance than the 0% Cr steel. This higher corrosion resistance of Cr steel samples could be due to the formation of Cr-rich hydro-oxide layers [Cr(OH)₃ as a corrosion product] on the surface of the samples. Thus, the epoxy-coated Cr alloy steel has greater corrosion resistance in a chloride-containing environment than the carbon steel. Hence, epoxy-coated Cr alloy steel can be successfully used as a construction material in structures.     

Supramolecular Organization in Fluorene/Indenofluorene– Oligothiophene Alternating Conjugated Copolymers

A series of conjugated copolymers containing fluorene or indenofluorene units alternating with oligothiophene segments, with potential interest for use as the active layer in field‐effect transistors, is investigated. Atomic force microscopy analysis of the morphology of thin deposits shows either the formation of fibrillar structures, which are the signature of long‐range π stacking, or the presence of untextured aggregates, resulting from disordered assembly. These morphologies are interpreted in terms of the supramolecular organization of the conjugated chains. Molecular modeling simulations indicate that the commensurability between the lengths of the monomer units and the presence of alkyl side groups are the two key structural factors governing the chain organization into highly ordered assemblies. The most favorable structures are those combining fluorene (indenofluorene) units with unsubstituted bithiophene (terthiophene) segments.     

Life Cycle Analysis and Green Design: A Context for Teaching Design,Environment, and Ethics

An exercise based on the concepts of green design and life cycle analysis is described. The details of the exercise and references are given to enable its use in classes. The problem provides a useful context in which to teach and discuss design, social relevance, and ethics, as well as to develop group and communication skills.     

MET-IDEA: data extraction tool for mass spectrometry-based metabolomics

A current and significant limitation to metabolomics is the large-scale, high-throughput conversion of raw chromatographically coupled mass spectrometry datasets into organized data matrices necessary for further statistical processing and data visualization. This article describes a new data extraction tool, MET-IDEA (Metabolomics Ion-based Data Extraction Algorithm) which surmounts this void. MET-IDEA is compatible with a diversity of chromatographically coupled mass spectrometry systems, generates an output similar to traditional quantification methods, utilizes the sensitivity and selectivity associated with selected ion quantification, and greatly reduces the time and effort necessary to obtain large-scale organized datasets by several orders of magnitude. The functionality of MET-IDEA is illustrated using metabolomics data obtained for elicited cell culture exudates from the model legume, Medicago truncatula. The results indicate that MET-IDEA is capable of rapidly extracting semiquantitative data from raw data files, which allows for more rapid biological insight. MET-IDEA is freely available to academic users upon request.     

A mechanical study of the deterioration of coconut leaf thatch under natural and accelerated environmental conditions

The deterioration of coconut leaf thatch, a cheap roofing material, has been studied by following the changes in strength on its exposure to both natural and accelerated environmental conditions such as natural weathering, accelerated conditions of rain and alternate wet and dry climate and micro-organisms such as fungus. Strength was found to decrease with time during deterioration. Scanning electron and stereo-optical microscopes were also used to study the fracture phenomena and surface changes during deterioration. It has been found that the major factors contributing to the deterioration of coconut leaf thatch are identified as rain, alternate wet and dry weather, decay by fungus and the brittle nature of the leaf itself. It appears from the present study that the deterioration of coconut leaf thatch occurs as a result of progressive embrittlement with possible contributions from environmental stress-cracking.     

Green tea extract: possible mechanism and antibacterial activity on skin pathogens

Camellia sinensis (tea) is known for its therapeutic properties (anti-inflammatory, anti-microbial, anti-tumour, anti-oxidative and anti-ageing). Although, anti-microbial properties of green tea have been studied, its role against bacterial strains related to skin infections and mechanism of action is not well understood. We focussed on exploring anti-microbial activity and the basic mechanism of aqueous green tea leaf extract on selected bacterial strains. Staphylococcus epidermidis, Micrococcus luteus, Brevibacterium linens, Pseudomonas fluorescens and Bacillus subtilis were found to be sensitive to green tea extract via disc diffusion assay (zone of inhibition ≥7 mm). Minimal inhibitory concentration (MIC) was determined via nitro blue tetrazolium (NBT) assay (0.156-0.313 mg/ml). Moreover, the aqueous extract was found to be not toxic to the Vero cell-line up to a concentration of 500 μg/ml. The effect of aqueous extract on adhesion of different bacteria to Vero cells indicated that it inhibits the adhesion at its MIC value.     

Short and long sleep duration and risk of drowsy driving and the role of subjective sleep insufficiency

Experimental sleep restriction increases sleepiness and impairs driving performance. However, it is unclear whether short sleep duration in the general population is associated with drowsy driving. The goal of the present study was to evaluate whether individuals in the general population who obtained sleep of 6 h or less are more likely to report drowsy driving, and evaluate the role of perceived sleep sufficiency. Data exploring whether subgroups of short sleepers (those who report the most or least unmet sleep need) show different risk profiles for drowsy driving are limited. From the 2009 Behavioral Risk Factor Surveillance System (N = 31,522), we obtained the following self-reported data: (1) sleep duration (≤5, 6, 7, 8, 9, or ≥10 h/night); (2) number of days/week of perceived insufficient sleep; (3) among drivers, yes/no response to: “During the past 30 days, have you ever nodded off or fallen asleep, even just for a brief moment, while driving?” (4) demographics, physical/mental health. Using 7 h/night as reference, logistic regression analyses evaluated whether self-reported sleep duration was associated with drowsy driving. Overall, 3.6% reported drowsy driving. Self-identified short-sleepers reported drowsy driving more often, and long sleepers, less often. Among those who perceived sleep as always insufficient, drowsy driving was reported more often when sleep duration was ≤5 h, 6 h, or ≥10 h. Among those who perceived sleep as always sufficient, drowsy driving was reported more often among ≤5 h and 6 h sleepers. Overall, drowsy driving was common, particularly in self-identified short-sleepers as a whole, as well as subgroups based on sleep insufficiency.