High-Resolution NMR and Magnetic Resonance Imaging (MRI) Studies on Fresh and Frozen Cod ( Gadus morhua) and Haddock (Melanogrammus aeglefinus)

Changes in the fish muscle from cod ( Gadus morhua ) and haddock ( Melanogrammus aeglefinus ) were investigated by high-resolution NMR and magnetic resonance imaging (MRI). Water- and salt-soluble extracts from fish stored at −20°C and −30°C were analysed by high-resolution proton NMR and enabled the identification of metabolites including trimethylamine oxide, trimethylamine (TMA) and dimethylamine. It was not possible to detect formaldehyde by NMR either in the stored fish samples or in spiked water or salt extracts even at high levels of formaldehyde addition, probably due to polymerisation. Systematic and controlled storage trials indicated the presence of dimethylamine at around 9 months for samples stored at −20°C, whereas no changes were detected at the control storage temperature of −30°C. A comparison of cod and haddock fillets stored for 1 year at −20 and −30°C confirmed the production of dimethylamine only in cod stored at −20°C. It was interesting to note that ‘fresh’ cod and haddock samples purchased from a local supermarket showed high levels of TMA indicating a breakdown of trimethylamine oxide to TMA by bacteria. TMA was not detected in the fish fillets especially obtained for the storage trials. MRI of fresh cod and fish stored at −8 and −30°C indicated that the fish half stored at −8°C exhibited dense lines or arches which are indicative of gaps in the tissue due to possible breakdown of the connective tissue. The images of fish stored at −30°C did not indicate any differences compared with the fresh fish. MRI also showed the presence of frozen and unfrozen areas in the fish non-destructively.     

Medicated Scaffolds Prepared with Hydroxyapatite/Streptomycin Nanoparticles Encapsulated into Polylactide Microfibers

The preparation, characterization, and controlled release of hydroxyapatite (HAp) nanoparticles loaded with streptomycin (STR) was studied. These nanoparticles are highly appropriate for the treatment of bacterial infections and are also promising for the treatment of cancer cells. The analyses involved scanning electron microscopy, dynamic light scattering (DLS) and Z-potential measurements, as well as infrared spectroscopy and X-ray diffraction. Both amorphous (ACP) and crystalline (cHAp) hydroxyapatite nanoparticles were considered since they differ in their release behavior (faster and slower for amorphous and crystalline particles, respectively). The encapsulated nanoparticles were finally incorporated into biodegradable and biocompatible polylactide (PLA) scaffolds. The STR load was carried out following different pathways during the synthesis/precipitation of the nanoparticles (i.e., nucleation steps) and also by simple adsorption once the nanoparticles were formed. The loaded nanoparticles were biocompatible according to the study of the cytotoxicity of extracts using different cell lines. FTIR microspectroscopy was also employed to evaluate the cytotoxic effect on cancer cell lines of nanoparticles internalized by endocytosis. The results were promising when amorphous nanoparticles were employed. The nanoparticles loaded with STR increased their size and changed their superficial negative charge to positive. The nanoparticles’ crystallinity decreased, with the consequence that their crystal sizes reduced, when STR was incorporated into their structure. STR maintained its antibacterial activity, although it was reduced during the adsorption into the nanoparticles formed. The STR release was faster from the amorphous ACP nanoparticles and slower from the crystalline cHAp nanoparticles. However, in both cases, the STR release was slower when incorporated in calcium and phosphate during the synthesis. The biocompatibility of these nanoparticles was assayed by two approximations. When extracts from the nanoparticles were evaluated in cultures of cell lines, no cytotoxic damage was observed at concentrations of less than 10 mg/mL. This demonstrated their biocompatibility. Another experiment using FTIR microspectroscopy evaluated the cytotoxic effect of nanoparticles internalized by endocytosis in cancer cells. The results demonstrated slight damage to the biomacromolecules when the cells were treated with ACP nanoparticles. Both ACP and cHAp nanoparticles were efficiently encapsulated in PLA electrospun matrices, providing functionality and bioactive properties.     

Electrical double-layer capacitors: evaluation of ageing phenomena during cycle life testing

This paper represents an assessment of the main ageing phenomena in electrical double-layer capacitors (EDLCs). In this study the cycle life of the EDLC cells with a rated capacitance of 1,600 F has been investigated at different ambient temperatures and current rates. From the experimental results we can observe that the impact of the high ambient temperature is significant on the cycle life of the cells. Moreover, the results also show the negative impact of the current rate. The internal resistance tests showed that the increase of the resistance is much higher than the decrease of the capacitance. Thus, the ageing of the EDLC during cycling was clearly non-linear. Further the EIS measurements indicated the higher increase of the imaginary part of the impedance at low frequencies during cycling, which indicates the capacitance fade.     

Pressure death and tailing behavior of Listeria monocytogenes strains having different barotolerances

The objectives of this study were to investigate the variability among Listeria monocytogenes strains in response to high-pressure processing, identify the most resistant strain as a potential target of pressure processing, and compare the inactivation kinetics of pressure-resistant and pressure-sensitive strains under a wide range (350 to 800 MPa) of pressure treatments. The pressure resistance of Listeria innocua and nine strains of L. monocytogenes was compared at 400 or 500 MPa and 30 degrees C. Significant variability among strains was observed. The decrease in log CFU/ml during the pressure treatment was from 1.4 to 4.3 at 400 MPa and from 3.9 to >8 at 500 MPa. L. monocytogenes OSY-8578 exhibited the greatest pressure resistance, Scott A showed the greatest pressure sensitivity, and L. innocua had intermediate resistance. On the basis of these findings, L. monocytogenes OSY-8578 is a potential target strain for high-pressure processing efficacy studies. The death kinetics of L. monocytogenes Scott A and OSY-8578 were investigated at 350 and 800 MPa. Survivors at 350 MPa were enumerated by direct plating, and survivors at 800 MPa were enumerated by the most-probable-number technique. Both pressure-resistant and pressure-sensitive strains exhibited non-first-order death behavior, and excessive pressure treatment did not eliminate the tailing phenomenon.     

Estimation of the activation of local reactor shielding concretes

Many elements in reactor shielding concrete become radioactive due to interaction with neutrons during the operation of a nuclear reactor. These radioactive elements will build up over the time due to (n,γ) reaction and contribute to the radioactive waste during decommissioning of the reactor, they will increase the dose from the inner part of the biological shielding (concrete) surrounding a nuclear reactor during maintenance works within reactor containment, and their effect should be taken in the calculations of the dose behind the concrete shield.Six mixtures of local ordinary and special shielding concretes have been investigated in this study. Their compositions were determined using X-ray diffraction and neutron activation analysis using the Syrian Miniature Neutron Source Reactor (MNSR) and consequently the dose rates.Based on the results of the analyses and comparing to the published limits in the references, it has been found that ⁶⁰Co, ¹⁵²Eu, ¹⁵⁴Eu and ¹³⁴Cs will be the most effective radioactive nuclides existing in the local concrete, but Dolomite aggregates contain the minimum limits of them and it has been found that Fe, Mg, and Ti the major elements existing in the local concrete.     

Lumped Parameter Thermal Model for Axial Flux Switched Reluctance Motors

The accurate prediction of temperature rise in various parts of a machine plays a significant role in ensuring that the machine delivers the required performance avoiding failures that arise due to high temperatures. In this paper, a lumped parameter thermal model is presented for exterior-rotor axial flux switched reluctance motors. Depending on its geometry, each part of the motor is modeled as a thermal equivalent circuit based on general cylindrical or cuboidal components. A total thermal network is obtained by proper connection of these sub-circuits. The model was calibrated by a stationary test; then, running conditions were applied to the model. The sensitivity of the model to the heat transfer coefficients was investigated by considering the effect of the coefficient variation on the estimated steady-state temperatures. Results show that the winding temperature, as the hottest part of the motor, is the most sensitive to the frame-to-ambient heat transfer coefficients.     

Large particle effects in chemical/biochemical heap leach processes - A review

The application of heap leach technology to recovery of economically important metals, notably copper, gold, silver, and uranium, is wide-spread in the mining industry. Unique to heap leaching is the relatively coarse particle size, typically 12-25 mm top size for crushed and agglomerated ores and larger for run-of-mine dump leaching operations. Leaching from such large particles is commonly assumed to follow shrinking core type behaviour, although little evidence for the validity of this assumption exists. This review investigates the current state of knowledge with respect to the understanding of the characteristics and mineralogy of large particles and how these influence leaching in a heap context and the tools to characterize these. This includes the study of ore and particle properties, visualization techniques for ore characterization, the connection between comminution and leaching behaviour, as well as particle models within heap leach modelling. We contend that the economics of heap leaching are strongly governed by the trade-off between the slow rate and limited extent of leaching from large particles and the cost of crushing finer. A sound understanding of the underlying large particle effects will therefore greatly inform future technology choices in the area of heap leaching.     

Making concrete with saline well-water

Permitted limits of salt concentrations in water used for making mortar and plain concrete differ from one country to another, but in any event geographical conditions prevent this guidance being applied directly to Saudi Arabia. Comparing the effects on compressive strength of saline well-water and drinking quality water, scientists at the Department of Building Research in the Saudi Arabian Standards Organisation show in this article that well-water with total dissolved salts (TDS) concentrations up to 4500 ppm can be suitable for mixing and curing mortars and plain concrete.     

Tea and coffee consumption in relation to vitamin D and calcium levels in Saudi adolescents

ABSTRACT: BACKGROUND: Coffee and tea consumption was hypothesized to interact with variants of vitamin D-receptor polymorphisms, but limited evidence exists. Here we determine for the first time whether increased coffee and tea consumption affects circulating levels of 25-hydroxyvitamin D in a cohort of Saudi adolescents. METHODS: A total of 330 randomly selected Saudi adolescents were included. Anthropometrics were recorded and fasting blood samples were analyzed for routine analysis of fasting glucose, lipid levels, calcium, albumin and phosphorous. Frequency of coffee and tea intake was noted. 25-hydroxyvitamin D levels were measured using enzyme-linked immunosorbent assays. RESULTS: Improved lipid profiles were observed in both boys and girls, as demonstrated by increased levels of HDL-cholesterol, even after controlling for age and BMI, among those consuming 9--12 cups of coffee/week. Vitamin D levels were significantly highest among those consuming 9--12 cups of tea/week in all subjects (p-value 0.009) independent of age, gender, BMI, physical activity and sun exposure. CONCLUSION: This study suggests a link between tea consumption and vitamin D levels in a cohort of Saudi adolescents, independent of age, BMI, gender, physical activity and sun exposure. These findings should be confirmed prospectively.     

Adaptive fuzzy semi‐decentralized control for a class of large‐scale nonlinear systems with unknown interconnections

In this paper, a general method is developed to generate a stable adaptive fuzzy semi‐decentralized control for a class of large‐scale interconnected nonlinear systems with unknown nonlinear subsystems and unknown nonlinear interconnections. In the developed control algorithms, fuzzy logic systems, using fuzzy basis functions (FBF), are employed to approximate the unknown subsystems and interconnection functions without imposing any constraints or assumptions about the interconnections. The proposed controller consists of primary and auxiliary parts, where both direct and indirect adaptive approaches for the primary control part are aiming to maintain the closed‐loop stability, whereas the auxiliary control part is designed to attenuate the fuzzy approximation errors. By using Lyapunov stability method, the proposed semi‐decentralized adaptive fuzzy control system is proved to be globally stable, with converging tracking errors to a desired performance. Simulation examples are presented to illustrate the effectiveness of the proposed controller. Copyright © 2006 John Wiley & Sons, Ltd.