New Evaluated Semi-Empirical Formula Using Optical Model for 14–15 MeV (<Emphasis Type="Italic">n</Emphasis>, <Emphasis Type="Italic">t</Emphasis>) Reaction Cross Sections

In the next century the world will face the need for new energy sources. Nuclear fusion can be one of the most attractive sources of energy from the viewpoint of safety and minimal environmental impact. Fusion will not produce CO₂ or SO₂ and thus will not contribute to global warming or acid rain. Achieving acceptable performance for a fusion power system in the areas of economics, safety and environmental acceptability, is critically dependent on performance of the blanket and diverter systems which are the primary heat recovery, plasma purification, and tritium breeding systems. Tritium self-sufficiency must be maintained for a commercial power plant. The hybrid reactor is a combination of the fusion and fission processes. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So working out the systematics of (n, t) reaction cross-sections are of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at energies up to 20 MeV. In this study, we have calculated non-elastic cross-sections by using optical model for (n, t) reactions at 14–15 MeV energy. We have investigated the excitation function character and reaction Q-values depending on the asymmetry term effect for the (n, t) reaction cross-sections. We have obtained new coefficients for the (n, t) reaction cross-sections. We have suggested semi-empirical formulas including optical model nonelastic effects by fitting two parameters for the (n, t) reaction cross-sections at 14–15 MeV. We have discussed the odd–even effect and the pairing effect considering binding energy systematic of the nuclear shell model for the new experimental data and new cross-sections formulas (n, t) reactions developed by Tel et al. We have determined a different parameter groups by the classification of nuclei into even–even, even–odd and odd–even for (n, t) reactions cross-sections. The obtained cross-section formulas with new coefficients have been discussed and compared with the available experimental data.     

Mechanisms of ion-induced GaN thin layer splitting

The underlying physics and the role of H-defect interaction in H ion-induced splitting of GaN were investigated by transmission electron microscopy, high resolution X-ray diffraction, positron annihilation spectroscopy, ion channeling, elastic recoil detection, and infrared spectroscopy. A high concentration of void-like nanoscopic structures, nanobubbles, is detected immediately after implantation. Positron annihilation measurements demonstrate that the detected structures are vacancy clusters. FTIR data show that H-defect vibrational spectrum peaks at 3141 cm^?1 mode attributed to V_Ga–H₄. A large fraction of H was found to be trapped in higher frequency modes which we associate tentatively to N–H stretch modes in the internal surfaces of nanobubbles. These nanobubbles persist during annealing up to 450 °C. An increase of the strain is observed in this temperature range. This strain relaxes partially above 450 °C following the formation of the platelets which are embryos of the microcracks.     

Er+ medium energy ion implantation into lithium niobate

Erbium-doped lithium niobate (Er:LiNbO₃) is a prospective photonics component, operating at 1.5 μm, which could find its use chiefly as an optical amplifier or waveguide laser. In this study, we have focused on the properties of the optically active Er:LiNbO₃ layers, which are fabricated by medium energy ion implantation under various experimental conditions. Erbium ions were implanted at energies of 330 and 500 keV with fluences of 1.0 × 10¹⁵, 2.5 × 10¹⁵ and 1.0 × 10¹⁶ cm^?2 into LiNbO₃ single-crystalline cuts of various orientations. The as-implanted samples were annealed in air at 350 °C for 5 h. The depth distribution and diffusion profiles of the implanted Er were measured by Rutherford Backscattering Spectroscopy (RBS) using 2 MeV He⁺ ions. The projected range R_P and projected range straggling ΔR_P were calculated employing the SRIM code. The damage distribution and structural changes were described using the RBS/channelling method. Changes of the lithium concentration depth distribution were studied by Neutron Depth Profiling (NDP). The photoluminescence spectra of the samples were measured to determine whether the emission was in the desired region of 1.5 μm. The obtained data made it possible to reveal the relations between the structural changes of erbium-implanted lithium niobate and its luminescence properties important for photonics applications.     

Plastic-containing materials as alternative reductants for base metal production

Shredder residue materials are produced after the removal of ferrous and non-ferrous fractions from end-of-life electronic equipment. Despite the high plastic content and metal value in the ash, high percentages of these materials are currently sent to landfills. In this study, the potential of utilising shredder residue material and other plastic-containing materials as reducing agents was studied. Plastic-containing materials were co-injected with coal into a zinc-fuming furnace in Boliden-Rönnskär smelter. The data obtained from the trial, such as the data from the chemical analysis of the slag and the steam production, are discussed. The observations indicate that plastic-containing material can replace up to 1?ton?h^?1 of coal without a significant decrease in the zinc reduction rate.     

Effect of Bath Depth and Nozzle Geometry on Spout Height in Submerged Gas Injection at Bottom

Metallurgical and Materials Transactions B - Spout height is a widely used parameter to quantitatively analyze the performance of the submerged gas injection in industrial applications. However,...     

A method for increasing the accuracy of “on-workpiece” machining with small industrial robots for composite repair

Composites offer outstanding mechanical properties in combination with a low density. To profit from the full potential of these materials there are still some challenges to meet. Efficient, reproducible, and material appropriate repair is one of them. It requires accurate machining on damaged structures to generate an optimal surface for the following bonded repair. In case of large scale structures, machining has to be done on-workpiece because those structures are not removable. This application requires a flexible, low-weight and cost-efficient machine, but also a system that considers the elasticities of on-work-piece machining setups. Small industrial robots offer high availability and flexibility, low investment costs, and a low weight in combination with a suitable workspace. The general disadvantage of these machines is a low stiffness in addition to the existing elasticities. However, in this application only moderate process forces occur. Furthermore, high system elasticity is expected any way, due to the detachable fixation and the workpiece. Accordingly, in this paper an online, low frequency method for the compensation of tool deviations is proposed to enhance the performance of small robots as on-workpiece milling machines. For a high industrial acceptance, a simple robot model for compensation is chosen, thus the measurement effort is minimal and the method can be integrated into a state of the art robot controller without external hardware. Additionally, a concept for an extended method for deviation compensation is presented which also considers the changing elasticity of fixation and workpiece.     

Influence of vacuum skin packaging on color stability of beef longissimus lumborum compared with vacuum and high-oxygen modified atmosphere packaging

The objective of this study was to investigate how color stability of beef is affected by vacuum skin packaging (VSP) compared with vacuum packaging (VP) and high-oxygen modified atmosphere packaging (MAP; 80% O(2) and 20% CO(2)). Longissimus lumborum muscles were aged in vacuum for 7days and then cut into 2-cm-thick slices and repacked using VSP, VP and MAP for another 7days. Color stability was measured during the next 5days in air and samples for α-tocopherol and NADH analyses were obtained at the beginning and end of aerobic storage. Color stability, α-tocopherol and NADH of steaks were affected by packaging methods and storage time in air (P<0.05). Higher a* value was obtained in VSP on day 5 compared with VP. Steaks packed in VSP had better color stability than in VP and their color was similar to MAP at the end (day 5) of storage.     

Quantitative risk assessment of listeriosis due to consumption of raw milk

The objectives of this study were to estimate the risk of illness for raw milk consumers due to Listeria monocytogenes in raw milk sold by permitted dealers, and the risk for people on farms who consume raw milk. Three scenarios were evaluated for raw milk sold by dealers: raw milk purchased directly from bulk tanks, from on-farm stores, and from retail. To assess the effect of mandatory testing of raw milk by regulatory agencies, the number of listeriosis cases per year was compared where no raw milk testing was done, only a screening test to issue a permit was conducted, and routine testing was conducted and milk was recalled if it was L. monocytogenes positive. The median number of listeriosis cases associated with consumption of raw milk from bulk tanks, farm stores, and retail for an intermediate-age population was 6.6 × 10(-7), 3.8 × 10(-5), and 5.1 × 10(-5) cases per year, respective ly. In populations with high susceptibility, the estimated median number of cases per year was 2.7 × 10(-7) (perinatal, i.e., pregnant women and their fetuses or newborns) and 1.4 × 10(-6) (elderly) for milk purchased from bulk tanks, 1.5 × 10(-5 ) (perinatal) and 7.8 × 10(-5) (elderly) for milk from farm stores, and 2.1 × 10(-5) (perinatal) and 1.0 × 10(-4) (elderly) for milk from retail. For raw milk consumed on farms, the median number of listeriosis cases was 1.4 × 10(-7) cases per year. A greater risk of listeriosis was associated with consumption of raw milk obtained from retail and farm stores as compared with milk obtained from bulk tanks. This was likely due to additional time-temperature combination steps in the retail and farm store models, which increased the chances for growth of L. monocytogenes in raw milk. A close relationship between prevalence of L. monocytogenes in raw milk and the values of disease incidence was observed. Hence, a reduction in the number of cases per year in all populations was observed when a raw milk-testing program was in place, especially when routine testing and recalling of milk was conducted.     

Environmental factors for phage-induced fermentation problems: replication and adsorption of the Lactococcus lactis phage P008 as influenced by temperature and pH

The lactococcal phage P008 was investigated for its growth characteristics under certain environmental conditions. Phage growth was characterized by the latency period, the average burst size (determined in one-step growth experiments) and by the percentage of adsorption to the host cells after 1, 5, 10 and 15 min (determined in modified one-step growth experiments). The incubation conditions studied were temperatures from 20 to 40 degrees C and pH values of 4.8 and 6.4. The growth medium was ultrafiltration permeate of skim milk, which forms the water phase of milk. Both, the temperature and the pH influenced the growth parameters: Increased temperature as well as low pH led to a faster latency along with a higher average burst size. The percentage of adsorption was at maximum when the standard conditions of 30 degrees C and pH 6.4 were applied. Below pH 5, adsorption was reduced to below 10%. A decrease of temperature slightly reduced phage multiplication. Data were incorporated into a model to simulate phage multiplication under certain conditions, taking the percentage adsorption into account. The cell destruction of the host culture was calculated accordingly. The simulation (extrapolation) was validated by experimental growth curves of phages and phage-infected host cultures.     

Mathematical model of Listeria monocytogenes cross-contamination in a fish processing plant

Listeriosis is a foodborne disease caused by the bacterium Listeria monocytogenes. The food industry and government agencies devote considerable resources to reducing contamination of ready-to-eat foods with L. monocytogenes. Because inactivation treatments can effectively eliminate L. monocytogenes present on raw materials, postprocessing cross-contamination from the processing plant environment appears to be responsible for most L. monocytogenes food contamination events. An improved understanding of cross-contamination pathways is critical to preventing L. monocytogenes contamination. Therefore, a plant-specific mathematical model of L. monocytogenes cross-contamination was developed, which described the transmission of L. monocytogenes contamination among food, food contact surfaces, employees' gloves, and the environment. A smoked fish processing plant was used as a model system. The model estimated that 10.7% (5th and 95th percentile, 0.05% and 22.3%, respectively) of food products in a lot are likely to be contaminated with L. monocytogenes. Sensitivity analysis identified the most significant input parameters as the frequency with which employees' gloves contact food and food contact surfaces, and the frequency of changing gloves. Scenario analysis indicated that the greatest reduction of the within-lot prevalence of contaminated food products can be achieved if the raw material entering the plant is free of contamination. Zero contamination of food products in a lot was possible but rare. This model could be used in a risk assessment to quantify the potential public health benefits of in-plant control strategies to reduce cross-contamination.