Deposition Uniformity and Particle Size Distribution of Ambient Aerosol Collected with a Rotating Drum Impactor

Rotating drum impactors (RDI) are cascade type impactors used for size and time resolved aerosol sampling, mostly followed by spectrometric analysis of the deposited material. They are characterized by one rectangular nozzle per stage and are equipped with an automated stepping mechanism for the impaction wheels. An existing three-stage rotating drum impactor was modified, to obtain new midpoint cutoff diameters at 2.5 μm, 1 μm, and 0.1 μm, respectively. For RDI samples collected under ambient air conditions, information on the size-segregation and the spatial uniformity of the deposited particles are key factors for a reliable spectrometric analysis of the RDI deposits. Two aerodynamic particle sizers (APS) were used for the determination of the RDI size fractionation characteristics, using polydisperse laboratory room air as quasi-stable proxy for urban ambient air. This experimental approach was suitable for the scope of this study, but was subject to numerous boundary conditions that limit a general use. Aerodynamic stage penetration midpoint diameters were estimated to be 2.4 and 1.0 μm for the first two RDI stages. Additionally, the spatial uniformity and geometrical size distribution of the deposited aerosol were investigated using micro-focus synchrotron radiation X-ray fluorescence spectrometry (micro-SR-XRF) and transmission electron microscopy (TEM), respectively. The size distribution of the particles found on the TEM samples agreed well with the results from the APS experiments. The RDI deposits showed sufficient uniformity for subsequent spectrometric analysis, but in the 2.5–10 μm size range the particle area density was very low. All of the applied methods confirmed the theoretical cutoff values of the modified RDI and showed that compared to other cascade impactors, the determined stage penetration sharpness was rather broad for the individual impactor stages.     

Development of a rapid, non-destructive method for egg content determination in dry pasta using FT-NIR technique

A quick, non-destructive method, based on Fourier transform near-infrared (FT-NIR) spectroscopy for egg content determination of dry pasta is presented. Multivariate calibration was carried out by using partial least squares (PLS) regression. A calibration set of 108 samples, a validation set of 22 samples and a prediction set of 11 samples of egg pasta were used. The diffuse reflection spectra of different types of pastas were measured by FT-NIR analyzer in the 800-2500 nm spectral range. The optimal results for egg content (root mean square error of prediction (RMSEP) = 0.7; R² = 90.7, Rank = 4) were obtained when the spectra were subjected to the first derivation combined with multiplicative scatter correction (MSC) and smoothing. Egg content was determined from FT-NIR results by introducing a mathematical correction step.     

Mechanisms of enterohemorrhagic Escherichia coli spread along the food-chain and precautionary measures

Enterohemorrhagic Escherichia coli (EHEC) are food-borne pathogens implicated in large outbreaks and sporadic cases of bloody diarrhea and the hemolytic uremic syndrome. The main reservoir of EHEC is the intestinal tract of ruminants, in particular cattle. Feces containing these bacteria may act as a source of contamination for the environment and particularly for a variety of foods. E. coli O157:H7 as well as other EHEC-serotypes have been isolated from domestic ruminants and non-ruminant farm animals as well as products produced from them, but also from drinking water, vegetables and dairy products. The main transmission pathway of the pathogens is the ingestion of raw or undercooked contaminated food but human infection can also occur by person-to-person transmission. This article will focus on the prevalence and spread of EHEC by vegetable foods, especially the less common EHEC transmission sources sprouts and leafy greens. It will discuss precautionary measures against the spread of EHEC in food at all stages of the food chain: the primary production, the industrial processing, the retailing as well as the consumer.     

A structural study of cadmium interaction with aquatic microorganisms

The molecular mechanisms of cadmium toxicity for aquatic phototrophic microorganisms, reversible adsorption on the surface, and cellular uptake during growth were investigated by combining batch macroscopic experiments with atomic-level in situ Cd K-edge X-ray absorption fine structure spectroscopy. The following species were examined: marine planktonic (Skeletonema costatum, Thalassiossira weissflogil) and freshwater periphytic (Navicula minima, Achnanthidium minutissum) diatoms, cyanobacteria (Gloeocapsa sp.), anoxygenic phototrophic bacteria (Rhodopseudomonas palustris), and freshwater diatom-dominated biofilms. Upon short-term adsorption at the freshwater diatoms and cyanobacteria cell surface from a NaNO3 or NaCl solution, Cd is octahedrally coordinated by oxygen at an average distance of 2.27 +/- 0.02 angstroms and is associated with carboxylate groups. The atomic environment of cadmium incorporated into freshwater diatoms during long-term growth (operationally defined as Cd nonextracted by EDTA) is similar to that of adsorbed metal in terms of Cd-O first-shell distances and coordination numbers. Contrasting speciation is found for Cd incorporated into marine diatoms and adsorbed onto phototrophic anoxygenic bacteria R. palustris, where Cd is coordinated with three to five oxygen/nitrogen atoms and one to three sulfur atoms in the first atomic shell, likely in the form of cysteine/hystidine complexes or Cd-thiolate clusters. The Cd association with sulfhydryl groups in marine planktonic diatoms and anoxygenic bacteria is an important feature of Cd binding which can be useful for assessing the bioavailability of this metal.     

Are school meals a viable and sustainable tool to improve the healthiness and sustainability of children´s diet and food consumption? A cross-national comparative perspective

There is little agreement among governments, institutions, scientists and food activists as to how to best tackle the challenging issues of health and sustainability in the food sector. This essay discusses the potential of school meals as a platform to promote healthy and sustainable food behavior. School meal programs are of particular interest for improving public diet because they reach children at a population scale across socio-economic classes and for over a decade of their lives, and because food habits of children are more malleable than those of adults. Current research on the history and health implications of school meal programs is reviewed in a cross-national comparative framework, and arguments explored that speak for the need of a new developmental phase of school meals as an integrative learning platform for healthy and sustainable food behavior. Nutritional, social, practical, educational, economical, political, and cultural perspectives and challenges linked to the implementation of healthy and sustainable school meals are discussed. Finally, the need for long-term interventions and evaluations is highlighted and new research directions are proposed.     

To act or not to act, that’s the problem: Primarily inhibition difficulties in adult ADHD.

Forty-nine carefully diagnosed adults with persistent attention deficit/hyperactivity disorder (ADHD), who had never been medicated for their ADHD, were compared with 49 normal control adults matched for age and gender on a large battery of tests in five domains of executive functioning (inhibition, fluency, planning, working memory, and set shifting) and several other neuropsychological functions to control for nonexecutive test demands. After stringent controls for nonexecutive function demands and IQ, adults with ADHD showed problems in inhibition and set shifting but not in any of the other executive functioning domains tested. We argue that adult ADHD may be mainly a disorder of inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pretreatment of aqueous pectin solution by cross‐flow microfiltration: analysis of operational parameters,degree of concentration and pectin losses

Obtaining pectin through traditional precipitation processes requires a large amount of organic solvent. A reduction in solvent consumption may be achieved by incorporating a cross‐flow microfiltration step in which the extraction solution is removed and pectin is concentrated. In this study, we used α‐alumina tubular membrane (0.44 μm) in two operation modes: total recycle mode to evaluate the effect of temperature, initial concentration of pectin and transmembrane pressure on the permeate flux and pectin coefficient rejection; and batch mode to evaluate the degree of concentration and loss of pectin. It was observed that pectin coefficient rejection varied from 93.4 ± 0.7% to 97.8 ± 0.3%, and a maximum permeate flux of 238.69 ± 6.48 kg m^?2 h^?1 with 0.12 MPa at 50 °C and 1.0 g kg^?1. Using the optimum conditions, the flux observed at the end of the process was 32.8% lower than the flux in the total recycle mode, enabling a final concentration of pectin in the retained solution of 61.04 ± 0.87% with an average pectin loss in the permeate stream of 8.18%.     

Reliability Consequences of Liberalization in the Electricity Sector: Existing Research and Remaining Questions

The generation, transmission and distribution of energy are among the most vital prerequisites for the functioning of modern societies. Since the early 1990s, the energy sectors of Western societies have been through a process of institutional restructuring, where large state‐owned monopolies have been divided into several independent organizations. Also, the organizations responsible for providing energy, like most other industrial organizations today, have made increasing use of outsourcing strategies. Taken together, these developments represent a significant change in the framework conditions for the energy sector. How this development affects the reliability of energy supply and the capacity for effective crisis management is an important question from both a research perspective as well as from a societal point of view. This article reviews the current literature on these issues, aiming to identify research gaps in the existing literature. Several research gaps are identified.