Organic compounds in office environments - sensory irritation, odor, measurements and the role of reactive chemistry

Abstract Sensory irritation and odor effects of organic compounds in indoor environments are reviewed. It is proposed to subdivide volatile organic compounds (VOCs) into four categories: (i) chemically non-reactive, (ii) chemically 'reactive', (iii) biologically reactive (i.e. form chemical bonds to receptor sites in mucous membranes) and (iv) toxic compounds. Chemically non-reactive VOCs are considered non-irritants at typical indoor air levels. However, compounds with low odor thresholds contribute to the overall perception of the indoor air quality. Reported sensory irritation may be the result of odor annoyance. It appears that odor thresholds for many VOCs probably are considerably lower than previously reported. This explains why many building materials persistently are perceived as odorous, although the concentrations of the detected organic compounds are close to or below their reported odor thresholds. Ozone reacts with certain alkenes to form a gas and aerosol phase of oxidation products, some of which are sensory irritants. However, all of the sensory irritating species have not yet been identified and whether the secondary aerosols (ultrafine and fine particles) contribute to sensory irritation requires investigation. Low relative humidity may exacerbate the sensory irritation impact. Practical Implications Certain odors, in addition to odor annoyance, may result in psychological effects and distraction from work. Some building materials continually cause perceivable odors, because the odor thresholds of the emitted compounds are low. Some oxidation products of alkenes (e.g. terpenes) may contribute to eye and airway symptoms under certain conditions and low relative humidity.     

Oxidative changes during ice storage of rainbow trout (Oncorhynchus mykiss) fed different ratios of marine and vegetable feed ingredients

Recently fish meal and oil have increasingly been replaced with proteins and oils from vegetable sources in the diets of farmed salmonids, but the consequences for the oxidative stability of the resulting fish products have not been investigated. The aim of the present study was to evaluate the influence of feeding regime on composition of rainbow trout fillets, as well as on lipid and protein oxidation during storage on ice. Rainbow trout were fed six different diets, which differed in their levels of marine oil and proteins vs. vegetable oil and protein. Fish fillets were characterised by measurement of fatty acid and amino acid composition, primary and secondary lipid oxidation products, astaxanthin and tocopherol content. Protein oxidation was assessed by measuring protein carbonyl content, oxidised amino acids, sulfhydryl groups and immuno-blotting against carbonyl groups. Feeding regimes significantly influenced fatty acid composition. Replacement of fish oil with vegetable oil reduced formation of primary oxidation products, but the effect on secondary oxidation products differed between different types of volatiles. The differences in protein and amino acid composition were not significant, and there were no clear effects of diets on protein oxidation, but data indicated that compounds present in the marine ingredients might have had an effect on protein oxidation.     

Analyzing and evaluating product demand interdependencies

Demand-driven manufacturing is an extremely unstable planning environment compared to forecast-driven manufacturing. This requires preparation and makes knowledge of demand behaviour even more important for planning and control. The basic assumptions of pre-ante allocation based on forecast of independent end-products demand are critical for manufacturing planning and control in general. However, the importance is higher for demand-driven manufacturing than forecast-driven manufacturing. This is due to the sensitivity of demand-driven manufacturing to demand fluctuations, e.g. time and interdependency of demand rates, due to the customer order decoupling point.This paper presents a method to establish time and interdependency of demand rates (the Time- and Interdependent Demand Rate Method), which can improve the planning and control performance as well as the order management performance in a MTO environment. The method is tested on data from two cases. For both cases results and demand planning implications are presented. Use guidelines for the method are also presented along with avenues of further research.     

Simulations of H2O2 concentration profiles in the water surrounding spent nuclear fuel

A simple mathematical model describing the hydrogen peroxide concentration profile in water surrounding a spent nuclear fuel pellet as a function of time has been developed. The water volume is divided into smaller elements, and the processes that affect hydrogen peroxide concentration are applied to each volume element. The model includes production of H₂O₂ from α-radiolysis, surface reaction between H₂O₂ and UO₂ and diffusion. Simulations show that the surface concentration of H₂O₂ increases fairly rapidly and approaches the steady-state concentration. The time to reach steady-state is sufficiently short to be neglected compared to the times of interest when simulating spent fuel dissolution under deep repository conditions. Consequently, the steady-state approach can be used to estimate the rate for radiation-induced spent nuclear fuel dissolution.     

In situ corrosion testing of various nickel alloys at Måbjerg waste incineration plant

The majority of waste in Denmark is disposed via waste to energy (WTE) incineration plants which are fabricated from carbon steel. However, due to the increasing corrosiveness of waste over the years, more corrosion resistant alloys are required. In Denmark, Inconel 625 (UNSN06625) is the weld overlay material currently being used to give improved corrosion resistance. In order to assess the use of alternative nickel alloys, test panels have been manufactured and inserted into Måbjerg waste incineration plant. Inconel 625 as a 50% weld overlay, two layered weld overlay and as a spiral weld overlay was exposed. Other nickel materials exposed were weld overlay Alloy 686, Alloy 50 and Sumitomo Super 625 coextruded tube. Exposure has been undertaken from 2003 to 2009 in the first pass and 2005–2009 in the second pass, and sections have been removed and investigated during this period. The composition of the deposits from the exposed waterwall panels was also analysed each time sections were removed. This paper will compare the various nickel alloys in the two areas and assess the results of the long‐term testing project.     

The Daktari: An interactive,multi-media tool for knowledge transfer among poor livestock keepers in Kenya

This article describes the findings from the assessment of a touch-screen, multi-media learning program on livestock health and production: The Daktari. The program was tested on a sample of 62 livestock keepers in the Nairobi slums of Kariobangi and Kibera. The study examined prior knowledge regarding three livestock diseases (liver fluke, mastitis and mange) and compared this to newly acquired knowledge after exposure to the software. The results demonstrated a significant difference between pre- and post-knowledge assessments confirming that use of the program led to learning. Learning occurred among a variety of demographic/social groups (i.e. age, gender and education) with a range of abilities. Indeed, by utilising an audio–visual interface developed with relevant content for the population in question, it was found that the program could support and enhance participant understanding of livestock disease causation, diagnosis, treatment and prevention.     

Ammonia Synthesis: Exploratory and Applied Research

Abstract

Exploratory and applied research in ammonia catalysis has two goals: to improve the activity and other desirable properties of the catalysts and to develop a variety of information required to obtain the best performance of the catalysts. In this latter category we have development of rate equations and parameters required to optimize reactor systems.     

Direct or indirect exposure of exhaled contaminants in stratified environments using an integral model of an expiratory jet

The risk of cross‐infection is high when the susceptible persons are exposed to the pathogen‐laden droplets or droplet nuclei exhaled by infectors. This study proposes a jet integral model to predict the dispersion of exhaled contaminants, evaluating the exposure risk and determining a threshold distance to identify the direct and indirect exposures in both thermally uniform and stratified environments. The results show that the maximum concentration of contaminants exhaled by a bed‐lying infector clearly decreases in a short distance (<1.8 m) in a uniform environment, while it maintains high values in a long distance in a stratified environment. The lock‐up phenomenon largely weakens the decay of the concentration. The direct exposure of the receiver is determined primarily by the impact scope of the exhaled airflow, while the indirect exposure is mainly related to the ventilation rate and air distribution in the room. In particular, the distance of direct exposure is the longest (approximately 2 m) when the receiver's breathing height is at the lock‐up layer in a stratified environment. Our study could be useful for developing effective prevention measures to control cross‐infection in the initial stage of design of indoor layouts and ventilation systems.     

Too Hot to Handle: The Controversial Hunt for Uranium in Greenland in the Early Cold War

Before WW2 Danish geologists had found traces of uranium in Greenland. But being squeezed from both sides in the escalating Cold War between East and West, in the first decade after WW2 the Danish government did not support expeditions to explore Greenland's potential uranium deposits. The situation changed abruptly after President Eisenhower's Atoms for Peace address in December 1953, as a result of which a Danish Atomic Energy Commission (AEK) was set up in early 1955. Besides building a large atomic energy research facility (Risø) one of AEK's first initiatives was to support big scale uranium expeditions to South‐West Greenland. The ultimate goal for the leaders of AEK was to liberate Denmark from its dependence on imported fossil fuels by developing Danish nuclear reactors, fuelled by natural uranium from Greenland. In the late 1960s, after more than a decade of uranium explorations, this was still a goal, albeit much more long term. For many reasons the hunt for uranium in Greenland after WW2 was unsuccessful, but the main ones were Danish sovereignty concerns, techno‐scientific nationalism and devastating institutional clashes of interests. The present paper will explore these problems.