Adsorption combined with ultrafiltration to remove organic matter from seawater

Organic fouling and biofouling are the major severe types of fouling of reverse osmosis (RO) membranes in seawater (SW) desalination. Low pressure membrane filtration such as ultrafiltration (UF) has been developed as a pre-treatment before reverse osmosis. However, UF alone may not be an effective enough pre-treatment because of the existence of low-molecular weight dissolved organic matter in seawater. Therefore, the objective of the present work is to study a hybrid process, powdered activated carbon (PAC) adsorption/UF, with real seawater and to evaluate its performance in terms of organic matter removal and membrane fouling. The effect of different PAC types and concentrations is evaluated. Stream-activated wood-based PAC addition increased marine organic matter removal by up to 70% in some conditions. Moreover, coupling PAC adsorption with UF decreased UF membrane fouling and the fouling occurring during short-term UF was totally reversible. It can be concluded that the hybrid PAC adsorption/UF process performed in crossflow filtration mode is a relevant pre-treatment process before RO desalination, allowing organic matter removal of 75% and showing no flux decline for short-term experiments.     

Interaktive Lernobjekte zur Logistik

This paper provides an overview on freely accessible, interactive learning objects in the area of logistics. The authors focus on complex topics and concepts that become more comprehensible by working with multi-media based interactive learning objects.     

Evaluation of sequential methods for the determination of butterfat fatty acid composition with emphasis ontrans-18:1 acids. Application to the study of seasonal variations in french butters

The successive steps of an integrated analytical procedure aimed at the accurate determination of butterfat fatty acid composition, includingtrans-18:1 acid content and profile, have been carefully checked. This sequential procedure includes: dispersion of a portion of butter in hexane/isopropanol (2:1, vol/vol) with anhydrous Na₂SO₄, filtration of aliquots of the suspension through a microfiltration unit, subsequent preparation of fatty acid isopropyl esters (FAIPE) with H₂SO₄ as a catalyst, and analysis of total FAIPE by capillary gas-liquid chromatography (GLC). Isolation oftrans-18:1 isomers was by silver-ion thin-layer chromatography (Ag-TLC), followed by extraction from the gel of combined saturated andtrans-monoenoic acids with a biphasic solvent system. Analysis of these fractions by GLC allows the accurate quantitation oftrans-18:1 acids with saturated acids (14:0, 16:0, and 18:0) as internal standards. A partial insight in the distribution oftrans-18:1 isomers can be obtained by GLC on a CP Sil 88 capillary column (Chrompack, Middelburg, The Netherlands). All steps of the procedure are quite reproducible, part of the coefficients of variation (generally less than 3%, mainly limited to butyric and stearic acids) being associated with GLC analysis (injection, integration of peaks) and, to a lesser extent, to FAIPE preparation. FAIPE appear to be of greater practical interest than any other fatty acid esters, including fatty acid methyl esters (FAME), for the quantitation of short-chain fatty acids, because peak area percentages, calculated by the integrator coupled to the flame-ionization detector, are almost equal (theoretically and experimentally) to fatty acid weight percentages and do not require correction factors. With this set of procedures, we have followed in detail the seasonal variations of fatty acids in butterfat, with sixty commercial samples of French butter collected at five different periods of the year. Important variations occur around mid-April, when cows are shifted from forage and concentrates during winters spent in their stalls to fresh grass in pastures. At this period, there is a decrease of 4:0–14:0 acids and of 16:0 (−2 and −6%, respectively), while 18:0 andcis- plustrans-18:1 acids rise suddenly (2 and 5%, respectively). These modifications then progressively disappear until late fall or early winter. Other variations are of minor quantitative importance. Although influenced by the season, the content of 18:2n-6 acid lies in the narrow range of 1.2–1.5%.Trans-18:1 acids, quantitated by GLC after Ag-TLC fractionation, are at their highest level in May–June (4.3% of total fatty acids), and at their lowest level between January and the end of March (2.4%), with a mean annual value of 3.3%. The proportion of vaccenic (trans-11 18:1) acid, relative to totaltrans-18:1 isomers, is higher in spring than in winter, with intermediate decreasing values in summer and fall, which supports the hypothesis that the level of this isomer is linked to the feed of the cattle, and probably to the amount of grass in the feed.     

Integrating Social Dimensions into Flood Cost Forecasting

Many people potentially affected by flooding will undertake measures to either control flood levels or mitigate the damaging effects of the flood (e.g. use of berms, flood gates, sand bags). However, not everyone is in a position to prevent or mitigate damages incurred by a flood event. Thus, while flood-related costs are determined through economic assessments, there are social dimensions to property protection that will impact the actual damages incurred. To incorporate these additional dimensions, an index is developed to identify areas of increased social vulnerability in relation to pre- and post-flood warning preparation to mitigate property damage and facilitate evacuation. Education level, income, age, and familial dependencies are considered as contributors to potential social vulnerability of residents to respond to immediate pre-emergency flood preparation, and these are integrated with technical damage calculations to provide greater context for flood management planning. A case study application to the Credit River basin in southwestern Ontario is used to demonstrate the methodology. Analyses demonstrate that in this example application, the areas most prone to financial damages are also those where people are potentially more socially vulnerable, and indicate that total damages may be far greater in these areas than physical and monetary damages alone.     

Expression and secretion of a recombinant ricin immunotoxin from murine myeloma cells

Expression plasmids carrying a humanized N901 immuno-globulinheavy chain gene (hN901HC) fused to a gene encoding the nativeB chain of ricin toxin (RTB), hN90 W CRTB, or a sugar bindingmutant of RTB, hN901HC-RTBgly, were constructed. In each case,the fused gene constructions were co-expressed in murine myelomacells (Sp2/0) with the gene for humanized N901 immunoglobulinlight chain to produce the secreted recombinant products hN901-RTBand hN901-RTBgly, respectively. When purified by affinity chromatography,both the hN901-RTB and hN901-RTBgly products were found to havean apparent molecular mass of M_r = 210 000 and to be composedof two hN901 antibody heavy chains each fused to a fulllengthcopy of RTB and two hN901 antibody light chains. In each ofthe recombinant fusions the hN901 antibody moiety retained thefull binding affinity and specificity for its cognate antigen,CD56. Moreover, when mixtures of hN901-RTB and native ricinA chain were incubated in the presence of the antigen-positivetarget cell line SW-2, antigen-specific potentiation of ricinA chain cytotoxicity was observed. It has been demonstratedpreviously that lectin activity of the B chain is essentialfor A chain cytotoxicity, and we conclude that the fused wild-typeB chain was properly folded and maintained lectin activity.These data demonstrate the feasibility of using recombinantricin B chain in an immunotoxin and of using mammalian cellculture for its expression. The use of recombinant hN901-RTBfusion protein to evaluate the contribution of the lectin activityof ricin B chain in the penetration of cell membranes by ricinA chain is proposed.     

Physical workload,trapezius muscle activity,and neck pain in nurses' night and day shifts: A physiological evaluation

The purpose of this study was to compare physical workload, electromyography (EMG) of the trapezius muscle, neck pain and mental well-being at work between night and day shifts in twenty Swiss nurses. Work pulse (average increase of heart rate over resting heart rate) was lower during night (27 bpm) compared to day shifts (34 bpm; p < 0.01). Relative arm acceleration also indicated less physical activity during night (82% of average) compared to day shifts (110%; p < 0.01). Rest periods were significantly longer during night shifts. Trapezius muscle rest time was longer during night (13% of shift duration) than day shifts (7%; p < 0.01) and the 50th percentile of EMG activity was smaller (p = 0.02), indicating more opportunities for muscle relaxation during night shifts. Neck pain and mental well-being at work were similar between shifts. Subjective perception of burden was similar between shifts despite less physical burden at night, suggesting there are other contributing factors.     

Evaluation of long- and short-handled hand hoes for land preparation, developed in a participatory manner among women vegetable farmers in The Gambia

Objective

This study evaluated land preparation interventions (new short- and long-handled hoes), developed in a participatory manner with women vegetable farmers in West Africa, and identified indicators of long-term adoption of these interventions.

Methods

Subjects (n = 48) engaged in timed trials, alternating between using an intervention tool and their traditional hand hoe to till specified plots of land. Heart rates were measured and subjects reported the relative ergonomic comfort and safeness of the tool after each trial. Follow-up interviews and focus groups were held one, two, and three months after the trials.

Results

Compared to the traditional hoe, the new long-handled hoe required 22% less time (p = 0.01), while the new short hoe took 20% more time (p = 0.05) to till the standard plots in this study. Two months after the initial trials, 94% of subjects preferred the new hoes over the traditional hoe. Most subjects (75%) preferred the new short hoe over the new long hoe and thought it was faster (81%), despite measurements to the contrary.

Conclusions

While the new long-handled hoe performed better in the timed trials in this study, most subjects preferred the new short-handled hoe. Subjects should be sensitized on the benefits of the long-handled hoe.     

A Memetic Algorithm for staff scheduling problem in airport security service

The staff scheduling problem is widely studied in Operational Research. Various surveys are available in the literature dealing with this problem which concerns various objectives and various constraints. In this article, we present a staff scheduling problem in airport security service. First, a modeling of the problem, and a representation of solutions are shown. The problem is solved in three steps, days-off scheduling, shift scheduling, and staff assignment. We focus on the last step, by providing a Memetic Algorithm (MA) which merged an Evolutionary Algorithm and Local Search techniques. We propose a chromosome encoding, a crossover operator and a combined neighborhood function, specially dedicated to this staff assignment problem. Besides providing better solutions than software currently used, this algorithm provides up to 50% of improvement from initial feasible solutions.