Fungal xylanases‐mediated synthesis of silver nanoparticles for catalytic and biomedical applications

Green synthesis of nanoparticles has fuelled the use of biomaterials to synthesise a variety of metallic nanoparticles. The current study investigates the use of xylanases of Aspergillus niger L3 (NEA) and Trichoderma longibrachiatum L2 (TEA) to synthesise silver nanoparticles (AgNPs). Characterisation of AgNPs was carried out using UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy, while their effectiveness as antimicrobial, antioxidant, catalytic, anticoagulant, and thrombolytic agents were determined. The colloidal AgNPs was brownish with surface plasmon resonance at 402.5 and 410 nm for NEA‐AgNPs and TEA‐AgNPs, respectively; while FTIR indicated that protein molecules were responsible for the capping and stabilisation of the nanoparticles. The spherical nanoparticles had size of 15.21–77.49 nm. The nanoparticles significantly inhibited the growth of tested bacteria (63.20–88.10%) and fungi (82.20–86.10%), and also scavenged DPPH (37.48–79.42%) and hydrogen peroxide (20.50–96.50%). In addition, the AgNPs degraded malachite green (78.97%) and methylene blue (25.30%). Furthermore, the AgNPs displayed excellent anticoagulant and thrombolytic activities using human blood. This study has demonstrated the potential of xylanases to synthesise AgNPs which is to the best of our knowledge the first record of such. The present study underscores the relevance of xylanases in nanobiotechnology.Inspec keywords: visible spectra, catalysis, ultraviolet spectra, silver, microorganisms, antibacterial activity, transmission electron microscopy, surface plasmon resonance, nanoparticles, nanofabrication, colloids, blood, Fourier transform infrared spectra, particle sizeOther keywords: Ag, fungal xylanases‐mediated synthesis, silver nanoparticles, catalytic applications, biomedical applications, green synthesis, metallic nanoparticles, Trichoderma longibrachiatum L2, transmission electron microscopy, antimicrobial agents, antioxidant agents, catalytic agents, thrombolytic agents, surface plasmon resonance, spherical nanoparticles, FTIR spectra, anticoagulant agents, colloidal nanoparticles, biomaterials, Aspergillus niger L3, UV‐vis spectroscopy, Fourier transform infrared spectroscopy, protein molecules, DPPH, hydrogen peroxide, malachite green, methylene blue, human blood, nanobiotechnology     

A novel medical image compression using Ripplet transform

In spite of great advancements in multimedia data storage and communication technologies, compression of medical data remains challenging. This paper presents a novel compression method for the compression of medical images. The proposed method uses Ripplet transform to represent singularities along arbitrarily shaped curves and Set Partitioning in Hierarchical Trees encoder to encode the significant coefficients. The main objective of the proposed method is to provide high quality compressed images by representing images at different scales and directions and to achieve high compression ratio. Experimental results obtained on a set of medical images demonstrate that besides providing multiresolution and high directionality, the proposed method attains high Peak Signal to Noise Ratio and significant compression ratio as compared with conventional and state-of-art compression methods.     

A two-step feature selection method for monitoring tool wear and its application to the coroning process

Coroning is a complex and multi-directional gear finishing process involving metal removal of gear teeth surface, and condition monitoring has not been applied to this process. In order to capture the progress of wear, an acoustic emission (AE) sensor is used, but the large data size of AE requires extensive dimension reduction and feature selection. The conventional method of averaging to reduce the data size may have the risk of losing information as higher frequencies are filtered off. A two-step feature selection method is implemented using class mean scatter criterion and modified relevance/redundancy analysis. This method results in feature dimension reduction and enhances classification performance. It involves first ranking candidate features by calculating their separability. Features which are correlated are then combined to reduce dimensions without averaging. Application of this two-step feature selection technique enables coroning tool wear to be monitored with a classification rate of 98.3 % compared to 94.1 % using conventional feature selection.     

Discovery and Mechanism of Type III Secretion System Inhibitors

The Type III Secretion System (TTSS) is indispensable for virulence of many Gram-negative pathogenic bacteria, including Escherichia coli, Salmonella spp., Yersinia spp., Vibrio spp., Chlamydia spp., Shigella spp., Pseudomonas spp., Xanthomonas spp., and Auromonas spp. Such pathogenic bacteria are responsible for diseases such as plague, shigellosis, chlamydia, cholera, pneumonia, and gastroenteritis. This review offers insights into the known inhibitors of the TTSS, their discovery, and their mode of action.     

Emerging bio-ethanol projects in Nigeria: Their opportunities and challenges

Despite being a major petroleum producing and exporting country, Nigeria has for a long time imported refined petroleum products for domestic consumption. The country has recently made an entrance into the bio-energy sector by seeding the market with imported ethanol until enough capability exists for the domestic production of ethanol. The Nigerian Biofuel Policy was released in 2007 calling for the domestic production of bio-ethanol to meet the national demand of 5.14 billion litres/year. Some investors have responded by investing over $3.86 billion for the construction of 19 ethanol bio-refineries, 10,000 units of mini-refineries and feedstock plantations for the production of over 2.66 billion litres of fuel grade ethanol per annum. Also, another 14 new projects are in the offing. Of the 20 pioneer projects, 4 are at the conception phase, 8 are in the planning phase, and 7 are under construction with only 1 operational. The potential benefits of the emerging bio-ethanol projects include investment in the economy, employment, energy security and boost rural infrastructure, while the major challenge is land take (859,561 ha). This is the first time an attempt is been made to document the emerging bio-ethanol projects in Nigeria.     

Polypropylene/carbon nanotube nanocomposite fibers: Process–morphology–property relationships

This study is focused on aligning carbon nanotubes in polypropylene matrix by melt spinning. Two different weight percentages (0.5% and 1.0%) of nanotubes were used for the synthesis of the nanocomposite fibers. The effect of the nanotubes on the crystallization and mechanical behavior of polypropylene as well as the effect of draw ratio on the nanocomposite morphology and properties is also discussed. Correlation of fiber morphology and nanotube alignment was done using differential scanning calorimetry, wide‐angle X‐ray diffraction, and transmission electron microscopy. Significant improvement in tensile modulus and tensile strength were observed, which is characteristic of a highly aligned nanotube system. A substantial vincrease in the onset of decomposition was observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3844–3850, 2007     

Optimizing 100%‐renewable grids through shifting residential water‐heater load

A low‐carbon electricity supply for Australia was simulated, and the installed capacity of the electrical grid was optimized by shifting the electricity demand of residential electric water heaters (EWHs). The load‐shifting potential of Australia was estimated for each hour of the simulation period using a nationwide aggregate EWH load model on a 90 × 110 raster grid. The electricity demand of water heaters was shifted from periods of low renewable resource and high demand to periods of high renewable resource and low demand, enabling us to effectively reduce the installed capacity requirements of a 100%‐renewable electricity grid. It was found that by shifting the EWH load by just 1 hour, the electricity demand of Australia could be met using purely renewable electricity at an installed capacity of 145 GW with a capacity factor of 30%, an electricity spillage of 20%, and a generation cost of 15.2 ¢/kWh. A breakdown of the primary energy sources used in our scenario is as follows: 43% wind, 29% concentrated solar thermal power, and 20% utility photovoltaic. Sensitivity analysis suggested that further reduction in installed capacity is possible by increasing the load‐shifting duration as well as the volume and insulation level of the EWH tank.     

What scope for integrating land management policies,land administration processes and data infrastructures for housing production in Nigeria?

Existing knowledge reveals that land as a resource is not currently managed efficiently and effectively in most countries of the world. One of the factors considered important in understanding the inefficiencies and ineffectiveness is the level of integration between agencies. The objective of this paper is to determine the level of this inefficiency in order to improve our understanding of the inter-relationship between agencies that perform land administration functions. The research methods include a synthesis of past studies and the use of case study approach. It uses as context, Lagos, in Nigeria. This approach involves a mixed method: interviews and online survey. The results revealed limited integration of processes and collaboration of agencies in the management of land for housing production. We conclude that policies are not sufficiently informed by data and there is a noticeable disconnection between agencies, and formulated policies.     

Development of engineered natural organic sorbents for environmental applications: 3. Reducing PAH mobility and bioavailability in contaminated soil and sediment systems

The effects of engineered natural organic amendments on two measures of the environmental "availability" of polycyclic aromatic hydrocarbons (PAHs) associated with soil and sediment samples are assessed. Two soils spiked with pyrene alone and a sediment spiked with a mixture of 4 PAH compounds were amended with raw or superheated-water processed peat or soybean stalks, then aged for periods of either 62 or 105 days. The aged soils were then examined with respect to bioaccumulation of spiked pyrene by earthworms (Eisenia foetida), and to its human bioaccessibility as measured by extraction with simulated gastrointestinal fluid. Additions of processed amendments reduced both measures of availability by factors ranging from 7.6 to 27.0 for earthworm bioaccumulation and from 2.3 to 8.8 for gastrointestinal extractability. All PAH compounds spiked to the sediment were reduced to varying extents in their availabilities to E. foetida and leachabilities by water by both processed and raw organic amendments.     

Electrospun bioactive nanocomposite scaffolds of polycaprolactone and nanohydroxyapatite for bone tissue engineering

Nanocomposite scaffolds based on nanofibrous poly(epsilon-caprolactone) (PCL) and nanohydroxyapatite (nanoHA) with different compositions (wt%) were prepared by electrostatic co-spinning to mimic the nano-features of the natural extracellular matrix (ECM). NanoHA was found to be well dispersed in polymers up to the addition of 20 wt%, after ultrasonication. The composite scaffolds were characterized for structure and morphology using XRD, EDX, SEM, and DSC. The scaffolds have a porous nanofibrous morphology with fibers (majority) having diameters in the range of 450-650 nm, depending on composition, and interconnected pore structures. SEM, EDX, and XRD analyses have confirmed the presence of nanoHA in the fibers. As the nanoHA content in the fibers increases, the surface of fibers becomes rougher. The mechanical (tensile) property measurement of the electrospun composites reveals that as the nanoHA content increases, the ultimate strength increases from 1.68 MPa for pure PCL to 2.17, 2.65, 3.91, and 5.49 MPa for PCL/nanoHA composites with the addition of 5, 10, 15, and 20 wt% nanoHA, respectively. Similarly the tensile modulus also increases gradually from 6.12 MPa to 21.05 MPa with the increase of nanoHA content in the PCL/nanoHA fibers, revealing an increase in stiffness of the fibers due to the presence of HA. DSC analysis reveals that as nanoHA in the composite scaffolds increases, the melting point slightly increases due to the good dispersion and interface bonding between PCL and nanoHA.