Chromium carbide–CNT nanocomposites with enhanced mechanical properties

Chromium carbide is widely used as a tribological coating material in high-temperature applications requiring high wear resistance and hardness. Herein, an attempt has been made to further enhance the mechanical and wear properties of chromium carbide coatings by reinforcing carbon nanotubes (CNTs) as a potential replacement of soft binder matrix using plasma spraying. The microstructures of the sprayed CNT-reinforced Cr₃C₂ coatings were characterized using transmission electron microscopy and scanning electron microscopy. The mechanical properties were assessed using micro-Vickers hardness, nanoindentation and wear measurements. CNT reinforcement improved the hardness of the coating by 40% and decreased the wear rate of the coating by almost 45–50%. Cr₃C₂ reinforced with 2 wt.% CNT had an elastic modulus 304.5 ± 29.2 GPa, hardness of 1175 ± 60 VH_0.300 and a coefficient of friction of 0.654. It was concluded that the CNT reinforcement increased the wear resistance by forming intersplat bridges while the improvement in the hardness was attributed to the deformation resistance of CNTs under indentation.     

Chromium (III) uptake by agro-waste biosorbents: Chemical characterization, sorption–desorption studies, and mechanism

Within their complex structure, agro-waste materials such as sorghum straw (SS), oats straw (OS) and agave bagasse (AB) have functional groups (i.e. carboxyl and phenolic) that play a major role in metals sorption. The advantages of these materials include availability, low-cost, and a reasonable metal sorption capacity. These agro-waste materials were chemically characterized by acid-base titrations and ATR-FTIR analyses in order to determine their functional groups, equilibrium constants, and surface charge distribution. Batch experiments were conducted at pH 3 and 4, at 25 °C and 35 °C to determine the biosorbents chromium (III) sorption capacity. Partially saturated biosorbents were desorbed with HNO₃, NaOH, and EDTA at different concentrations and temperatures (25 °C, 35 °C, and 55 °C). Finally, the chromium (III) sorption mechanism was discussed.Agro-waste materials functional groups are associated, in part, to carboxyl and hydroxyl groups: these oxygen-containing sites play an important role in the chromium (III) removal. The maximum chromium (III) sorption capacity was 6.96, 12.97, and 11.44 mg/g at pH 4 for acid-washed SS, OS, and AB, respectively. The chromium (III) sorption capacity decreased at pH 3 because H⁺ ions competed for the same functional groups. On the other hand, an increase in temperature enhanced both the biosorbents chromium (III) sorption capacity and their desorption by EDTA. The most probable chromium (III) sorption mechanisms were ion exchange and complexation.The agro-waste materials studied herein efficiently remove chromium (III) from aqueous solution and, most importantly, EDTA can efficiently desorb Cr (III) from agro-waste materials at 55 °C.     

Phenolics and antioxidant capacity of table grape (Vitis vinifera L.) cultivars grown in Chile

Grapes (Vitis vinifera L.) possess health-promoting effects attributed to their supply of a wide variety of bioactive phenolics. Juice and skin fractions of 4 varieties of table grapes: Red Globe, Crimson Seedless, Autumn Royal, and Ribier were prepared to determine and compare their total phenolics content, antioxidant capacity (DPPH, FRAP, and ORAC), anthocyanins, and specific phenolics (caffeic acid, gallic acid, resveratrol, and catechin) content, since a series of positive health benefits are expected from the intake of any of these fractions. Higher amounts of total phenolics and antioxidant capacity were observed in the skin fractions (P < 0.05). Blue grapes (Autumn Royal and Ribier) exhibited higher phenolics content and antioxidant capacity (P < 0.05) than red grapes. The most abundant phenolic compound observed was catechin (P < 0.05). Significant correlations between the antioxidant capacity and total phenolics were observed in grape juice and skin fractions. Autumn Royal juice provides a very high amount of phenolics, anthocyanins, and exhibits the highest antioxidant capacity, offering the best health promoting properties compared with the other grape varieties studied. PRACTICAL APPLICATION: Grapes possess health-promoting effects attributed to their supply of a wide variety of bioactive phenolics. Grape juice made with blue grapes (Autumn Royal, Ribier) exhibit higher phenolics content and antioxidant capacity than juice elaborated with red grapes (Red Globe, Crimson Seedless). The skin is a good source of phenolics and has a high antioxidant capacity. Specific health-promoting phenolics are more abundant in blue grapes, mainly in their skin fraction, which should not be discarded.     

On the initial propagation of dental caries

A multi-dimensional model for dental caries is applied to study the shape of caries lesions in a realistic tooth geometry and to examine the rate of progress of caries. An upgraded model, taking into account the outer prismless enamel layer, is derived and solved. The model demonstrates the importance of this layer in delaying the onset of caries. The conclusions are discussed in light of experimental results.     

Bridge Maintenance Level Assessment

Parameters in assessing the effectiveness of maintenance tasks on the overall cost of a bridge or system of bridges are identified and the linkage among maintenance, condition rating, and cost is made by subdividing the subjective process into smaller parts. Experience with New York City bridges is used to develop a life expectancy model once the maintenance and repair protocol is specified. Results for several sample maintenance allocations are given to show how a rapid spreadsheet calculation can provide a basis for comparing maintenance alternatives and to point in the direction of an optimized allocation of limited budgets.     

A satellite data set for tropical forest area change assessment

A database of largely cloud-free (less than 2.5% of all sites have more than 5% cloud cover), geo-referenced 20 km?×?20 km sample sites of 30 m resolution optical satellite imagery have been prepared for the 1990 and 2000 epochs. This spans the tropics with a systematic sample located at the degree confluence points of the geographic grid. The resulting 4016 sample pairs are to be used to measure changes in the area of forest cover between the two epochs. The primary data source was the National Aeronautics and Space Administration's (NASA's) global land survey (GLS) data sets. Visual screening of GLS images at all 4016 confluence points from each date identified 2868 suitable pairs where no better alternatives exist (71.6% of the sample). Better alternatives could be found for 26.6% of the sample, substituting cloudy or missing GLS data sets at one or the other epoch or both (GLS-1990 or GLS-2000). Gaps were filled from the United States Geological Survey (USGS) Landsat archives (1070 samples), data from other Landsat archives (53 samples) or with alternatives to Landsat, that is, 15 samples from Satellite Pour l'Observation de la Terre (SPOT). This increased the effective number of sample pairs to 3945 representing 98% of all target samples. No suitable image pairs were found for 71 confluence points, which were not randomly distributed, but mostly concentrated in the Congo basin, where around 15% of the region remains un-sampled. Variations in date of image acquisition and geometric fidelity are documented. Results highlight the importance of combining systematic data-processing schemes with targeted image acquisition and archiving strategies for global scale applications such as deforestation monitoring and shows that by replacing cloudy or missing GLS data with alternative imagery, the overall coverage of the sample sites within the ecological zones ‘Tropical rainforest’ and ‘Tropical mountain system’ can be improved by 16%.     

Automating the semantic mapping between regulatory guidelines and organizational processes

The mapping of regulatory guidelines with organizational processes is an important aspect of a regulatory-compliance management system. Automating this mapping process can greatly improve the overall compliance process. Currently, there is research on mapping between different entities such as ontology mapping, sentence similarity, semantic similarity and regulation-requirement mapping. However, there has not been adequate research on the automation of the mapping process between regulatory guidelines and organizational processes. In this paper, we explain how Natural Language Processing and Semantic Web technologies can be applied in this area. In particular, we explain how we can take advantage of the structures of regulation-ontology and the process-ontology in order to compute the similarity between a regulatory guideline and a process. Our methodology is validated using a case study in the Pharmaceutical industry, which has shown promising results.