Quantifying changes in weak layer microstructure associated with artificial load changes

Researchers and practitioners have long utilized a variety of penetrometers to investigate the snowpack. Identifying definitive relationships between penetrometer-derived microstructural information and stability has been challenging. The purpose of this study is two-fold: 1. We propose a simple field test to establish relationships between load and penetrometer-derived microstructural estimates, 2. We utilize the SnowMicroPen (SMP) to quantify changes in weak layer residual strength and microstructural dimension associated with an artificial loading event. Our dataset is from Moonlight Basin, Montana and includes three modified loaded-column tests, each paired with 5 SMP profiles. Depth hoar comprised the targeted weak layer. Results indicate that loading caused the residual strength and rupture frequency to decrease significantly. Much like a compression test at a micro-scale, the force required for the SMP to rupture individual structures as well as the micro-scale strength decreased significantly when the slab stress was increased by artificially adding blocks of snow. A decrease in observed rupture frequency within the weak layer (or an increase in the distance between ruptured structures) also occurred after the loading event, probably because some structures within the weak layer had already failed or were so close to failing that the penetrometer could not detect their rupture. Due in part to the large difference in loads, microstructural differences between the natural and loaded columns were significant enough that only one profile would have been necessary to determine a significant difference in residual strength. Artificial removal of slab stress resulted in greater rupture forces and larger microstructures, likely due to elastic rebound.     

Planar FET oscillators using periodic microstrip patch antennas

An integrated oscillator/antenna is presented that uses a single microstrip leaky-wave structure as both the resonant and the radiating element. This resonant antenna is connected to a GaAs metal-semiconductor field-effect transistor which acts as the negative resistance element in the oscillator circuit. This type of oscillator is similar in its operating principle to one reported using Gunn diodes and a periodically notched dielectric image guide. This circuit exhibits the high DC-RF conversion efficiency that is typical of field-effect transistor oscillators. The planar circuit is simple and inexpensive to construct, occupies a small volume, and can conform to different surface profiles. Such circuits are suitable for use in millimeter-wave systems as well as at microwave frequencies. A design procedure is given, and the performance of X-band prototype circuits is reported. Prototype circuits showed a 9 dB isotropic conversion gain and 40 MHz tuning range at 9.5 GHz     

Technical note – effects of seaming conditions on external and internal double‐seam characteristics in round metal cans

Canning is the major packaging technology for fully preserved food products. To obtain safe canned foods with extended shelf‐life, the closed cans have to be hermetic. The consistency and quality of the seaming process are crucial to food safety. This note investigates the effects of different seaming conditions (base‐plate pressure and seaming‐roller pressure) on external (seam thickness, seam height) and internal (body hook length, overlap, lid hook length, seam gap and body hook butting) double‐seam characteristics in round metal cans. External double‐seam characteristics were significantly affected by the seaming‐roller pressure during the final closure of the cans. Generally, there were small effects of base‐plate pressure on the external double‐seam characteristics. In contrast, all the investigated double‐seam characteristics were affected significantly by the seaming‐roller pressure, whereas only body hook length and seam gap were significantly affected by the base‐plate pressure. This note illustrates the importance of close control and optimization of the seaming conditions during production of canned foods as a means to reduce the processing induced variability in double‐seam characteristics, and subsequently to obtain safe and high‐quality canned products. Copyright © 2005 John Wiley & Sons, Ltd.     

Production of Salmon Oil from Filleting Byproducts—Effects of Storage Conditions on Lipid Oxidation and Content of ω‐3 Polyunsaturated Fatty Acids

ABSTRACT: Filleting byproducts (heads, frame bones, skin, and down‐graded gutted fish) from farmed Atlantic salmon (Salmo salar) were separated into a solid/aqueous phase and a lipid phase (oil) using a scraped‐surface heat exchanger (90 °C to 95 °C) and a decanter centrifuge (93 °C). Effects of storage temperature (4 °C and 23 °C), atmosphere (air and N₂), and time (0 to 180 d), as well as an additional process step—a separator introduced after the decanter centrifuge, were investigated on the quality and storage stability of the produced oil. Samples were analyzed for the quality parameters peroxide (PV), anisidine (AV), and Totox value (TxV), content of free fatty acids (FFA), content of fatty acid methyl esters (FAME), especially the n‐3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and degradation of EPA and DHA related to the content of hexadecanoic acid (HDA) (ratios EPA/HDA and DHA/HDA). Storage temperature had significant effect on all the investigated quality parameters, especially on AV, PV, and TxV where a high storage temperature (23 °C) caused a 10‐fold, 2.5‐fold, and 4‐fold increase in AV, PV, and TxV, respectively. Storage atmosphere had significant effect on all the investigated parameters, except on the DHA/HDA ratio, where storage under an N₂ atmosphere significantly preserved the quality of the oil compared with storage in air. Generally, no significant effect of storage time on the investigated quality parameters was observed before 120 d of storage. No effect on quality was observed when introducing an additional processing step (separator) after the decanter centrifuge. Salmon oil is a stable product, and even more so when stored at appropriate conditions (under nitrogen atmosphere at refrigerated temperatures).     

The quality of cold-smoked Atlantic salmon (Salmo salar) as affected by salting method, time and temperature

The effects of temperature (4 and 10–12 °C) and time (6, 12 and 24 h) on colorimetric parameters (Commission International de l'Eclairage (CIE) L*a*b*), carotenoid concentration, salt content and yield were investigated in brine (saturated or 50% saturation) and dry salted fillets of cold‐smoked Atlantic salmon (Salmo salar). Lightness (L*), yellowness (b*), hue (H_ab) and chroma (C*) values were lower at 10 than 4 °C (P < 0.01), whereas redness (a*) was unaffected. L* increased (P < 0.05) and a*, b*, H_ab and C* values dropped when salting time was increased (P < 0.001). Astaxanthin concentration of brine‐salted fillets decreased with increasing salting time (P < 0.05), but was unaffected by salting temperature. Increasing salting time affected colour negatively. The salt content of dry salted fillets increased with temperature and salting time. The process yield was unaffected by temperature and decreased with salting time. In conclusion, the cold smoking process is more important for variation in quality parameters than the salting process.     

Demonstration of safety of probiotics -- a review

Probiotics are commonly defined as viable microorganisms (bacteria or yeasts) that exhibit a beneficial effect on the health of the host when they are ingested. They are used in foods, especially in fermented dairy products, but also in pharmaceutical preparations. The development of new probiotic strains aims at more active beneficial organisms. In the case of novel microorganisms and modified organisms the question of their safety and the risk to benefit ratio have to be assessed. Lactic acid bacteria (LAB) in foods have a long history of safe use. Members of the genera Lactococcus and Lactobacillus are most commonly given generally-recognised-as-safe (GRAS) status whilst members of the genera Streptococcus and Enterococcus and some other genera of LAB contain some opportunistic pathogens. Lactic acid bacteria are intrinsically resistant to many antibiotics. In many cases resistances are not, however, transmissible, and the species are also sensitive to many clinically used antibiotics even in the case of a lactic acid bacteria- associated opportunistic infection. Therefore no particular safety concern is associated with intrinsic type of resistance. Plasmid-associated antibiotic resistance, which occasionally occurs, is another matter because of the possibility of the resistance spreading to other, more harmful species and genera. The transmissible enterococcal resistance against glycopeptide antibiotics (vancomycin and teicoplanin) is particularly noteworthy, as vancomycin is one of the last effective antibiotics left in the treatment of certain multidrug-resistant pathogens. New species and more specific strains of probiotic bacteria are constantly identified. Prior to incorporating new strains into products their efficacy should be carefully assessed, and a case by case evaluation as to whether they share the safety status of traditional food-grade organisms should be made. The current documentation of adverse effects in the literature is reviewed. Future recommendations for the safety of already existing and new probiotics will be given.     

Output‐Sensitive Filtering of Streaming Volume Data

Real‐time volume data acquisition poses substantial challenges for the traditional visualization pipeline where data enhancement is typically seen as a pre‐processing step. In the case of 4D ultrasound data, for instance, costly processing operations to reduce noise and to remove artefacts need to be executed for every frame. To enable the use of high‐quality filtering operations in such scenarios, we propose an output‐sensitive approach to the visualization of streaming volume data. Our method evaluates the potential contribution of all voxels to the final image, allowing us to skip expensive processing operations that have little or no effect on the visualization. As filtering operations modify the data values which may affect the visibility, our main contribution is a fast scheme to predict their maximum effect on the final image. Our approach prioritizes filtering of voxels with high contribution to the final visualization based on a maximal permissible error per pixel. With zero permissible error, the optimized filtering will yield a result that is identical to filtering of the entire volume. We provide a thorough technical evaluation of the approach and demonstrate it on several typical scenarios that require on‐the‐fly processing.     

Biodiversity offsetting and net positive design

Biodiversity offsetting is used in both urban development and regional resource consent processes to compensate for unavoidable environmental impacts. Using North American, Australian and New Zealand examples, the limitations, opportunities and contradictions of the conventional approach in biodiversity offsetting schemes relevant to the built urban environment were reviewed. It was found that there is not adequate accounting for incremental and cumulative effects over time and space, especially given ecological uncertainty. Benchmarking against current conditions has sanctioned a gradual loss of ecological carrying capacity and biodiversity. Net biodiversity gains are possible, but this will require shifts in frameworks for assessing both buildings and biodiversity offsets towards net positive planning and design.     

Feed supplement recovered from dairy wastewater by biological and chemical pretreatment

A continuous process for treatment of dairy wastewater with immobilized lactic acid bacteria has been demonstrated at pilot scale. A strain of Lactobacillus plantarum was selected on the basis of a high conversion rate of lactose at low pH, a high affinity of lactose at low concentrations, and the ability to retain activity for a long time immobilized in alginate beads. Lactose was converted to lactic acid, which lowered the pH and precipitated milk proteins. The proteins were separated together with milk fat by flotation with carboxy methyl cellulose (CMC) or chitosan and gave a solid phase of approx. 10% dry matter (23% protein and 68% fat). The total chemical oxygen demand (COD_t) removed varied from 65 to 78% for CMC and 49 to 82% for chitosan. The precipitated material was used as a feed supplement for pigs to provide up to 30% of the total energy intake. No adverse effects on the pig's performance were observed. The energy feed value of the precipitate was estimated to be 2·0 feed units (FUs) per kg dry matter. © 1998 Society of Chemical Industry