HPLC determination of polycyclic aromatic hydrocarbons (PAHs) in the littoral urban sewage area of cortiou (Marseille,France)

A selective method for determining polycyclic aromatic hydrocarbons (PAHs) in sediments using solid‐phase extraction and RP‐HPLC with fluorescence and UV detection is described. The complete analytical method is used to surface sediments from the creek of Cortiou (France). Sewage from the urban area of Marseille is delivered to the creek. PAH levels in sediments (µg/g) range between 2.251 µg/g (for the benzo(a)anthracene) and 相似文献   

Future directions in physiochemical modeling of the thermodynamics of polyelectrolyte coacervates

We review theories of polyelectrolyte (PE) coacervation, which is the spontaneous association of oppositely charged units of PEs and phase separation into a polymer-dense phase in aqueous solution. The simplest theories can be divided into “physics-based” and “chemistry-based” approaches. In the former, PEs are treated as charged, long-chain, molecules, defined by charge level, chain length, and chain flexibility, but otherwise lacking chemical identity, with electrostatic interactions driving coacervation. The “chemistry-based” approaches focus on the local interactions between the species for which chemical identity is critical, and describe coacervation as the result of competitive local binding interactions of monomers and salts. In this article, we show how these approaches complement each other by presenting recent approaches that take both physical and chemical effects into account. Finally, we suggest future directions toward producing theories that are made quantitatively predictive by accounting for both long range electrostatic and local chemically specific interactions.     

The view from the top

The challenge of integrating large amounts of renewable energy resources into the electric sector requires updated transmission analysis techniques. Economic planning, primarily in the form of value-based planning over interconnectionwide areas, is needed before performing the traditional single-hour, capacity-based reliability analyses.     

Stocking wild adult Florida largemouth bass (Micropterus salmoides floridanus): An additional fish management tool

Stocking of largemouth bass is an important management tool for fish management. The stocking of hatchery‐produced fingerling or advanced‐fingerling bass to supplement bass year‐classes, however, has exhibited varying success. Utilizing a different approach, a multiyear stocking programme using wild adult largemouth bass was initiated at the Harris Chain of Lakes (3800 ha Lake Griffin; 1811 ha Lake Dora) in central Florida. Wild adult bass (24 781 fish), ranging in size from 200 mm total length (TL) to over 600 mm TL, were stocked in Lake Griffin (13 932 fish) and Lake Dora (10 849 fish). One month after stocking, the number of stocked bass caught in electrofishing catches in Lake Griffin and Lake Dora was ~10% and 22%, respectively. Estimates of mortality were similar to the native largemouth bass, although the movement of stocked fish into other connecting water bodies was extensive. For the Lake Griffin/Lake Dora stocking programme, bass were transferred at a cost of $10.09–19.89 per fish, depending on how the costs of the project are calculated ($250 000 for just the capture and transport of the fish vs. $492 775 for the total project). Considering only capture and transport costs, conservative benefit/cost ratio estimates would be $1.77/$1.00 spent for replacement and $1.85/$1.00 spent recreational costs, although the benefit/cost ratios could exceed $10/$1. Based on the present study, stocking wild adult largemouth bass is a cost‐effective tool for managing largemouth bass.     

An information-processing model of the decision to seek professional help.

Despite the presence of quality mental health care in many communities, people tend to avoid seeking help and wind up languishing in their problems unnecessarily. For the professional to better understand how to reach these individuals, an information-processing model is presented that examines the effects of people's interpretation of their environment and their symptoms on their decision to seek mental health services. Using the model as a guide, suggestions are presented for practitioners who wish to provide services to those who are in need of professional help, yet are hesitant to obtain it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Education via advanced technologies

Advanced technologies like the World Wide Web offer interesting opportunities for improving higher education. A study done at the Massachusetts Institute of Technology (MIT) focused on these matters and made several specific recommendations. Since this study was completed, a new center was established at MIT to coordinate and promote the use of advanced technologies in education, and a high-level council on educational technology was formed. After briefly peering into the future, this paper describes the study and the new center     

Carrier-phase time transfer

We have conducted several time-transfer experiments using the phase of the GPS carrier rather than the code, as is done in current GPS-based time-transfer systems. Atomic clocks were connected to geodetic GPS receivers; we then used the GPS carrier-phase observations to estimate relative clock behavior at 6-minute intervals. GPS carrier-phase time transfer is more than an order of magnitude more precise than GPS common view time transfer and agrees, within the experimental uncertainty, with two-way satellite time-transfer measurements for a 2400 km baseline. GPS carrier-phase time transfer has a stability of 100 ps, which translates into a frequency uncertainty of about two parts in 10(-15) for an average time of 1 day.     

Biochemical basis for a cholesterol-lowering activity of 2-[2"-(1",3"-dioxolane)]-2-methyl-4-(2'-oxo-1'-pyrrolidinyl)-6- nitro-2H-1-benzopyran (SKP-450), a novel antihypertensive agent

Administration (p.o.) of SKP-450, 2-[2"-(1",3"-dioxolane)]-2-methyl-4-(2'-oxo-1'-pyrrolidinyl)-6-nitro-2H- 1-benzopyran, a novel antihypertensive agent, to hypercholesterolemic Syrian hamsters led to a significant reduction in plasma lipids in a dose-dependent manner, i.e., a 10.8% to 29% reduction in low-density lipoprotein cholesterol at doses of 0.3 to 10 mg/kg of SKP-450. SKP-450 was found to specifically inhibit the hepatic microsomal lanosterol 14alpha-methyl demethylase (14alpha-DM) in a competitive manner (Ki:2.65 microM). Furthermore, a dose-dependent decrease in the 14alpha-DM activity by SKP-450 parallelled the cholesterol synthetic rate in vitro in both the rat hepatic S10 fractions (supernatants at 10,000 g; IC50:20 microM) and Chinese hamster ovary cells (IC50:23 microM). However, this phenomenon was not seen in AR45 cells, which are deficient in 14alpha-DM, suggesting that 14alpha-DM is the major target for the inhibitory action of SKP-450 in regard to cholesterol biosynthesis.