Effect of oxygen availability and pH on the furan concentration formed during thermal preservation of plant-based foods

Thermally treated fruit- and vegetable-based foods are important contributors to the furan exposure of children and adults. Furan reduction by adding or removing precursors from the product has proven to be challenging because of major food constituents and interactions involved in the reaction pathways leading to furan formation. Instead of intervening at the precursor level, it might be more feasible to influence these formation pathways by adjusting the matrix properties of the product. As opposed to many previous literature sources, the present study investigated the effects of oxygen availability (normal versus reduced) and pH (acid versus low acid) on the furan formation in a real food system. Different combinations of both matrix properties were prepared in a reconstituted potato purée and subjected to a thermal treatment with a pasteurisation or sterilisation intensity. Irrespective of the addition of the furan precursors ascorbic acid, fructose and fatty acids, a considerable furan reduction was observed for the sterilised purées (F₁₂₁¹⁰ = 15 min) with either a reduced oxygen availability (0.1–1.8 mg l^–1) or at pH 3. The effects of both matrix properties were less pronounced in the pasteurised purées (P₉₀¹⁰ = 10 min), because of the lower furan concentrations. Even though the mechanisms of furan reduction for both types of matrix properties could not be fully elucidated, the results showed that lowering the oxygen concentration or pH prior to thermal processing offers a powerful, additional strategy for furan mitigation in thermally treated plant-based foods.     

Concrete Slabs Reinforced with FRP Grids. I: One-Way Bending

Currently, considerable interest exists in the use of fiber-reinforced polymer (FRP) reinforcement for concrete structures. Due to the generally lower modulus of elasticity of FRP in comparison with steel and the linear behavior of FRP, certain aspects of the structural behavior of RC members reinforced with FRP may be substantially different from similar elements reinforced with steel reinforcement. In this two-part paper the use of different types of FRP grid reinforcement for concrete slabs is investigated, presenting detailed experimental and analytical work. In the first part, the structural behavior in one-way bending is considered. This paper shows which structural measures are needed to ensure acceptable serviceability behavior. The presented analysis and discussion of test results covers the ultimate state and the ultimate limit state for bending, serviceability limit states, ductility, deformability, and ultimate to service load ratio.     

Realization of fiber-based laser Doppler vibrometer with serrodyne frequency shifting

We demonstrate a laser Doppler vibrometer (LDV) based on the serrodyne frequency shifting technique. A proof-of-principle system is implemented on the basis of fiber-optic components but opens the way toward an ultracompact integrated LDV system on a silicon chip. With a low laser power of 50 μW, the serrodyne LDV was able to measure submicrometer vibrations with frequencies in the audio range.     

Performance analysis of sleep mode mechanisms in the presence of bidirectional traffic

Short battery life being a major impediment to a more widespread use of wireless devices, industry standards like WiMAX and 3GPP Long Term Evolution (LTE) embed power saving mechanisms in their protocol stack. Trading in network delay performance for extended battery life, these mechanisms require a careful balance to optimize overall network performance. Therefore, this paper assesses the impact of these mechanisms on network delay performance and battery life, thereby refining existing performance studies of the power saving mechanisms. In particular, this paper explicitly takes into account presence of both downlink and uplink traffic and their influence on the power saving mechanism. This contrasts with previous studies, where the analyses only accounted for downlink traffic. We obtain numerically efficient procedures to compute packet delay as well as energy efficiency characteristics under Markovian traffic. Then, performance of power saving is investigated by some numerical examples. Our results clearly indicate that uplink traffic heavily impacts the energy efficiency of the power saving mechanism.     

A coordinated investigation of the combustion chemistry of diisopropyl ketone,a prototype for biofuels produced by endophytic fungi

Several classes of endophytic fungi have been recently identified that convert cellulosic biomass to a range of ketones and other oxygenated molecules, which are potentially viable as biofuels, but whose oxidation chemistry is not yet well understood. In this work, we present a predictive kinetics model describing the pyrolysis and oxidation of diisopropyl ketone (DIPK) that was generated automatically using the Reaction Mechanism Generator (RMG) software package. The model predictions are evaluated against three experiments that cover a range of temperatures, pressures, and oxygen concentrations: (1) Synchrotron photoionization mass spectrometry (PIMS) measurements of pyrolysis in the range 800–1340 K at 30 Torr and 760 Torr; (2) Synchrotron PIMS measurements of laser photolytic Cl-initiated oxidation from 550 K to 700 K at 8 Torr; and (3) Rapid-compression machine measurements of ignition delay between 591 K and 720 K near 10 bar. Improvements made to the model parameters, particularly in the areas of hydrogen abstraction from the initial DIPK molecule and low-temperature peroxy chemistry, are discussed. Our ability to automatically generate this model and systematically improve its parameters without fitting to the experimental results demonstrates the usefulness of the predictive chemical kinetics paradigm.     

Size resolved ultrafine particles emission model--a continues size distribution approach

A new parameterization for size resolved ultrafine particles (UFP) traffic emissions is proposed based on the results of PARTICULATES project (Samaras et al., 2005). It includes the emission factors from the Emission Inventory Guidebook (2006) (total number of particles, #/km/veh), the shape of the corresponding particle size distribution given in PARTICULATES and data for the traffic activity. The output of the model UFPEM (UltraFine Particle Emission Model) is a sum of continuous distributions of ultrafine particles emissions per vehicle type (passenger cars and heavy duty vehicles), fuel (petrol and diesel) and average speed representative for urban, rural and highway driving.The results from the parameterization are compared with measured total number of ultrafine particles and size distributions in a tunnel in Antwerp (Belgium). The measured UFP concentration over the entire campaign shows a close relation to the traffic activity. The modelled concentration is found to be lower than the measured in the campaign. The average emission factor from the measurement is 4.29E + 14 #/km/veh whereas the calculated is around 30% lower. A comparison of emission factors with literature is done as well and in overall a good agreement is found.For the size distributions it is found that the measured distributions consist of three modes — Nucleation, Aitken and accumulation and most of the ultrafine particles belong to the Nucleation and the Aitken modes. The modelled Aitken mode (peak around 0.04-0.05 μm) is found in a good agreement both as amplitude of the peak and the number of particles whereas the modelled Nucleation mode is shifted to smaller diameters and the peak is much lower that the observed.Time scale analysis shows that at 300 m in the tunnel coagulation and deposition are slow and therefore neglected.The UFPEM emission model can be used as a source term in dispersion models.     

An interdisciplinary framework to predict premature roller element bearing failures in wind turbine gearboxes

Forschung im Ingenieurwesen - Roller element bearings present in the intermediate and high-speed stages of wind turbine gearboxes operate in dynamic working conditions and in some cases may fail...     

A Transaction Model for XML Databases

The hierarchical and semistructured nature of XML data may cause complicated update behavior. Updates should not be limited to entire document trees, but should ideally involve subtrees and even individual elements. Providing a suitable scheduling algorithm for semistructured data can significantly improve collaboration systems that store their data—e.g., word processing documents or vector graphics—as XML documents. In this paper we show that concurrency control mechanisms in CVS, relational, and object-oriented database systems are inadequate for collaborative systems based on semistructured data. We therefore propose two new locking schemes based on path locks which are tightly coupled to the document instance. We also introduce two scheduling algorithms that can both be used with any of the two proposed path lock schemes. We prove that both schedulers guarantee serializability, and show that the conflict rules are necessary.     

Effect of Oral Taurine on Morbidity and Mortality in Elderly Hip Fracture Patients: A Randomized Trial

Hip fracture patients represent a large part of the elderly surgical population and face severe postoperative morbidity and excessive mortality compared to adult surgical hip fracture patients. Low antioxidant status and taurine deficiency is common in the elderly, and may negatively affect postoperative outcome. We hypothesized that taurine, an antioxidant, could improve clinical outcome in the elderly hip fracture patient. A double blind randomized, placebo controlled, clinical trial was conducted on elderly hip fracture patients. Supplementation started after admission and before surgery up to the sixth postoperative day. Markers of oxidative status were measured during hospitalization, and postoperative outcome was monitored for one year after surgery. Taurine supplementation did not improve in-hospital morbidity, medical comorbidities during the first year, or mortality during the first year. Taurine supplementation lowered postoperative oxidative stress, as shown by lower urinary 8-hydroxy-2-deoxyguanosine levels (Generalized estimating equations (GEE) analysis average difference over time; regression coefficient (Beta): −0.54; 95% CI: −1.08–−0.01; p = 0.04), blunted plasma malondialdehyde response (Beta: 1.58; 95% CI: 0.00–3.15; p = 0.05) and a trend towards lower lactate to pyruvate ratio (Beta: −1.10; 95% CI: −2.33–0.12; p = 0.08). We concluded that peri-operative taurine supplementation attenuated postoperative oxidative stress in elderly hip fracture patients, but did not improve postoperative morbidity and mortality.     

Safety effects of an extensive black spot treatment programme in Flanders-Belgium

Black spot management is a widely implemented measure to improve traffic safety. This study evaluates the safety effects of an extensive black spot programme that has been implemented in Flanders-Belgium. In total, around 800 black spots were selected, from which 134 locations, redesigned between 2004 and 2007, were included in this study. The adopted approach is an empirical Bayes before- and after study that accounts for effects of general trends and for the stochastic nature of crashes, including regression to the mean. Two different comparison groups were established. The analyses showed a decrease in the number of injury crashes of 24–27%, significant at the 1%-level. A separate analysis for crashes with serious or fatal injuries showed a decrease of 46–57%, also significant at the 1% level. The highest effects were found for the implementation of changes in the layout of priority controlled intersections and for the installation of traffic signals, which showed a decrease of respectively 42% and 35% in the number of injury crashes. Signalized intersections at which left-turn phasing was implemented resulted in a decrease of 22% in the number of injury crashes, changes in the layout leaded to a decrease of 11%. The conversion of intersections (both signalized and priority controlled) into roundabouts resulted in a decrease of 21% in injury crashes. The black spot programme generated a favourable effect on each of the road user categories (car occupants, moped riders, cyclists, motorcyclist, pedestrians and truck drivers).