Comparison of the Axial Dispersion Performance of Pulsed Solvent Extraction Columns with Tenova Pulsed Column–Kinetics Internals and Standard Disc and Doughnut Internals

Axial dispersion performance of a 2-m high 76-mm diameter pilot-scale pulsed solvent extraction column has been studied using two liquid–liquid systems, Alamine 336/isodecanol/Shellsol 2046 (continuous)–tap water (dispersed) and LIX 84/Shellsol 2046 (continuous)–tap water (dispersed). The pulsed column was operated with standard disc and doughnut internals and Tenova pulsed column–kinetics internals using pulsation intensities from 0.005 m/s to 0.025 m/s with polyvinylidene fluoride internal plates of 22.4% open area. The effect of pulsation intensity, dispersed phase velocity, and continuous phase velocity on axial dispersion coefficient have been investigated and compared with the two different column internals, and the experimental data has been correlated with empirical relationships.     

Pathways for arsenic from sediments to groundwater to streams: Biogeochemical processes in the Inner Coastal Plain, New Jersey, USA

The Cretaceous and Tertiary sediments that underlie the Inner Coastal Plain of New Jersey contain the arsenic-rich mineral glauconite. Streambed sediments in two Inner Coastal Plain streams (Crosswicks and Raccoon Creeks) that traverse these glauconitic deposits are enriched in arsenic (15-25 mg/kg), and groundwater discharging to the streams contains elevated levels of arsenic (>80 μg/L at a site on Crosswicks Creek) with arsenite generally the dominant species. Low dissolved oxygen, low or undetectable levels of nitrate and sulfate, detectable sulfide concentrations, and high concentrations of iron and dissolved organic carbon (DOC) in the groundwater indicate that reducing environments are present beneath the streambeds and that microbial activity, fueled by the DOC, is involved in releasing arsenic and iron from the geologic materials. In groundwater with the highest arsenic concentrations at Crosswicks Creek, arsenic respiratory reductase gene (arrA) indicated the presence of arsenic-reducing microbes. From extracted DNA, 16s rRNA gene sequences indicate the microbial community may include arsenic-reducing bacteria that have not yet been described. Once in the stream, iron is oxidized and precipitates as hydroxide coatings on the sediments. Arsenite also is oxidized and co-precipitates with or is sorbed to the iron hydroxides. Consequently, dissolved arsenic concentrations are lower in streamwater than in the groundwater, but the arsenic contributed by groundwater becomes part of the arsenic load in the stream when sediments are suspended during high flow. A strong positive relation between concentrations of arsenic and DOC in the groundwater samples indicates that any process—natural or anthropogenic—that increases the organic carbon concentration in the groundwater could stimulate microbial activity and thus increase the amount of arsenic that is released from the geologic materials.     

The role and challenges of new diagnostic technology in plant biosecurity

Pest and pathogens pose a major threat to food security and the natural environment, and these threats are moving around the globe. Trade, travel and transport have major roles to play in this and thus to improve plant biosecurity, we need enhanced phytosanitary inspection systems. In order to achieve this, there is a role for the more effective use of diagnostic technology, such as field-based testing or the use of next generation sequencing technology. In this review we examine the opportunities and challenges posed by using new technology within a plant biosecurity context, but in contrast to previous reviews, here we focus on practical challenges associated with deployment and routine use, rather than specific technical issues. These key challenges include the need to accelerate the development and deployment of new technologies into the field, the accelerated discovery of new pathogens and the need for new risk assessment approaches, and improvements to our understanding of how best to deploy and use new diagnostic tools for maximum impact. Throughout we focus on how interdisciplinary approaches are important to help us improve our understanding and achieve our goals.     

Book reviews

This article describes the planning activity in Portugal in the middle of the twentieth century, notably the work of two exceptional planners, Etienne de Groër and Antão Almeida Garrett. The article moves from a first overview on the national context, to a focus on the two largest cities of Portugal, Lisbon, and Oporto. It was there that these two planners developed their most successful planning proposals. The planning activity of de Groër and Garrett is presented, first taken in isolation and then on a comparative basis. Issues addressed include the urban structure and the organization of the city, the street layout, and the system of zoning. It is argued that de Groër municipal plan for Lisbon and Garrett municipal plan for Oporto were able to leave a profound and lasting impact on these cities, being the most influential planning documents of the twentieth century in Lisbon and in Oporto.     

Recent trends in home and work smoking bans

Objectives: Home and work smoking bans at the national and state level in the USA, and their relation to smoking prevalence and to tobacco control policies, are examined.

Data: The Current Population Survey's 1992/93 and 1998/99 tobacco use supplement surveys are the primary data source, supplemented with information on state level tobacco control policies.

Methods: The national and state rate of bans are estimated, and changes over the course of the 1990s and their relation to smoking rates and tobacco control policies are examined.

Results: The prevalence of work and home bans has increased considerably between 1992/93 and 1998/99. By 1999, over 65% of the population age 15 and above work in places with smoking bans, and over 60% live in homes with bans. We found that states with lower than average ban rates in 1993 tended to have had larger increases in ban rates between 1993 and 1999. We also found that home and work bans became more prevalent in states with initially low smoking rates, and that the growth in home bans coincided with a declining prevalence of smoking. States with higher levels of bans by 1999 also tended to have higher cigarette taxes, stricter clean air laws, and media/comprehensive campaigns in place.

Conclusions: The results indicate that lower smoking rates are associated with higher rates of work and home bans, although substantial progress has also been made by those states with initially low rates of bans. While further work is needed to establish the direction of causality, it would appear that reductions in smoking rates, either through stronger tobacco control policies or otherwise, may reduce exposure to tobacco smoke not only by reducing the number of smokers, but also through increasing the number of firms and homes with smoking restrictions.

     

Examining the Leaders of Creative Efforts: What Do They Do,and What Do They Think About?

Due to the rapidly changing economy, innovation is becoming more and more critical for the success and survival of many organizations. Although several factors shaping innovation (e.g., strategy, climate, etc.) have been examined in the literature, the leadership of innovation has received relatively less attention. In this article, we attempt to summarize the literature on the leadership of creative efforts focusing on critical leadership behaviours. We also explore a model of core leader functions tailored for creativity and innovation, as well as a model of innovation planning. The implications of these models for the leadership of innovation are discussed.     

Randomized trial comparing vigabatrin and hydrocortisone in infantile spasms due to tuberous sclerosis

Vigabatrin has been shown to be efficient in infants with infantile spasms and tuberous sclerosis, in open studies. In order to compare vigabatrin to oral steroids, a prospective randomized multicenter study was implemented using both drugs as monotherapy in newly diagnosed patients with infantile spasms and tuberous sclerosis. Eleven infants received vigabatrin (150 mg/kg per day) and 11 hydrocortisone (15 mg/kg per day) for 1 month. Spasm free patients continued vigabatrin or progressively stopped hydrocortisone in 1 month, non-responders were crossed to the other drug for a new 2 month-period. All vigabatrin patients (11/11) were spasm-free versus 5/11 hydrocortisone infants (P < 0.01). Seven patients were crossed to vigabatrin (six for inefficacy, one for adverse events) and became also totally controlled. Mean time to disappearance of infantile spasms was 3.5 days on vigabatrin versus 13 days on hydrocortisone (P < 0.01). Five patients exhibited side effects on vigabatrin but nine on hydrocortisone (P = 0.006). Vigabatrin should therefore be considered as the first choice treatment for infantile spasms due to tuberous sclerosis.