bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical and biological analysis of endocrine-disrupting hormones and estrogenic activity in an advanced sewage treatment plant
Authors: Muller Mathieu , Rabenoelina Fanja , Balaguer Patrick , Patureau Dominique , Lemenach Karin , Budzinski Hélène , Barceló Damia , López de Alda Miren , Kuster Marina , Delgenès Jean-Philippe , Hernandez-Raquet Guillermina
Published: July 2008

The steroid hormones estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), and their conjugated forms were surveyed throughout an advanced sewage treatment plant (STP). The estrogen concentrations in water and sludge samples, collected in October 2004 and April 2005, were determined by gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. Simultaneously, the estrogenic activity was quantified using estrogen-responsive reporter cell lines (MELN) to investigate the behavior of overall estrogenic compounds. The estrogen concentrations in the inlet ranged from 200 to 500 ng/L, with the contribution of conjugated forms being higher than 50%. The major estrogens in influent were E1 and E3. The estrogenic activity was between 25 and 130 ng/L of E2 equivalents (EEQs). Estrogen concentrations and estrogenicity measured in the inlet and in primary treated sewage were similar, showing a weak impact of primary treatment on hormone removal. In contrast, both estrogen concentration and estrogenicity decreased during biological treatment, with high removal efficiencies (>90%). Estrone, E2, and EE2 persisted in the treated water below 10 ng/L, whereas the estrogenicity was lower than 5 ng/L of EEQs. Estrogen mass flux in the effluent and sludge represented less than 2 and 4%, respectively, of the inlet. Consequently, the fraction of estrogens sorbed into the sludge was very small, and biodegradation was the main vehicle for estrogen elimination. This dual approach, comparing chemical and biological analysis, allowed us to confirm that most of the estrogenic activity occurring in this STP, which receives mainly domestic sewage, resulted from sex hormones.
Influence of soil properties on copper toxicity for two soil invertebrates
Authors: Criel Peggy , Lock Koen , Van Eeckhout Hilde , Oorts Koen , Smolders Erik , Janssen Colin R
Published: July 2008

Although a large body of evidence indicates that metal toxicity to soil organisms is affected by physicochemical soil properties, use of this knowledge in ecological risk assessments is limited because of the lack of a model applicable to a wide range of soils. To study the effect of soil characteristics on the toxicity of copper to terrestrial invertebrates, chronic toxicity tests with Eisenia fetida and Folsomia candida were performed in 19 European field soils. These soils were carefully selected to cover the range of toxicity-influencing parameters encountered in the European Union. Toxicity values varied greatly among soils, with 28-d median effect concentrations ranging from 72.0 to 781 mg Cu/kg dry weight for E. fetida and from 45.4 to 2,270 mg Cu/kg dry weight for F. candida. For both species, variation in copper toxicity values was best explained by differences in the actual cation-exchange capacity (CEC) at soil pH. Using the obtained regression algorithms, the observed toxicity could, in most cases, be predicted within a factor of two for E. fetida and within a factor of three for F. candida. The developed models were validated in three additional European field soils, a standard artificial soil and a standard field soil. The presented regression equations, based on the actual CEC, offer an easy-to-apply method for taking the influence of soil properties on metal toxicity into account.
Development and validation of a congener-specific photodegradation model for polybrominated diphenyl ethers
Authors: Zeng Xia , Simonich Staci L. Massey , Robrock Kristin R , Korytár Peter , Alvarez-Cohen Lisa , Barofsky Douglas F
Published: July 2008

With the phaseout of the manufacture of some polybrominated diphenyl ether (PBDE) formulations, namely penta-brominated diphenyl ether (BDE) and octa-BDE, and the continued use of the deca-BDE formulation, it is important to be able to predict the photodegradation of the more highly brominated congeners. A model was developed and validated to predict the products and their relative concentrations from the photodegradation of PBDEs. The enthalpies of formation of the 209 PBDE congeners were calculated, and the relative reaction rate constants were obtained. The predicted reaction rate constants for PBDEs show linear correlation with previous experimental results. Because of their large volume use, their presence in the environment, and/or importance in the photodegradation of the deca-BDE formulation, BDE-209, BDE-184, BDE-100, and BDE-99 were chosen for further ultraviolet photodegradation experiments in isooctane. The photodegradation model successfully predicted the products of the photochemical reactions of PBDEs in experimental studies. A gas chromatography retention time model for PBDEs was developed using a multiple linear regression analysis and, together with the photodegradation model and additional PBDE standards, provided a way to identify unknown products from PBDE photodegradation experiments. Based on the results of the photodegradation experiments, as well as the model predictions, it appears that the photodegradation of PBDEs is a first-order reaction and, further, that the rate-determining step is the stepwise loss of bromine. Our results suggest that, based on photodegradation, over time, BDE-99 will remain the most abundant penta-BDE, while BDE-49 and BDE-66 will increase greatly and will be comparable in abundance to BDE-47.
Utilization of protein expression profiles as indicators of environmental impairment of smallmouth bass (Micropterus dolomieu) from the Shenandoah River, Virginia, USA
Authors: Ripley Jennifer , Iwanowicz Luke , Blazer Vicki , Foran Christy
Published: July 2008

The Shenandoah River (VA, USA), the largest tributary of the Potomac River (MD, USA) and an important source of drinking water, has been the site of extensive fish kills since 2004. Previous investigations indicate environmental stressors may be adversely modulating the immune system of smallmouth bass (Micropterus dolomieu) and other species. Anterior kidney (AK) tissue, the major site of blood cell production in fish, was collected from smallmouth bass at three sites along the Shenandoah River. The tissue was divided for immune function and proteomics analyses. Bactericidal activity and respiratory burst were significantly different between North Fork and mainstem Shenandoah River smallmouth bass, whereas South Fork AK tissue did not significantly differ in either of these measures compared with the other sites. Cytotoxic cell activity was highest among South Fork and lowest among North Fork AK leukocytes. The composite two-dimension gels of the North Fork and mainstem smallmouth bass AK tissues contained 584 and 591 spots, respectively. South Fork smallmouth bass AK expressed only 335 proteins. Nineteen of 50 proteins analyzed by matrix-assisted laser desorption ionization-time of flight were successfully identified. Three of the four identified proteins with increased expression in South Fork AK tissue were involved in metabolism. Seven proteins exclusive to mainstem and North Fork smallmouth bass AK and expressed at comparable abundances serve immune and stress response functions. The proteomics data indicate these fish differ in metabolic capacity of AK tissue and in the ability to produce functional leukocytes. The variable responses of the immune function assays further indicate disruption to the immune system. Our results allow us to hypothesize underlying physiological changes that may relate to fish kills and suggest relevant contaminants known to produce similar physiological disruption.
Ecotoxicological environmental risk limits for total petroleum hydrocarbons on the basis of internal lipid concentrations
Authors: Verbruggen Eric M. J , Beek Margriet , Pijnenburg Janny , Traas Theo P
Published: July 2008

A method is described for deriving ecotoxicological environmental risk limits (ERLs) for total petroleum hydrocarbons (TPH). Toxicity data for two oil types (light and heavy) to benthic organisms and corresponding estimated internal lipid concentrations, calculated by equilibrium partitioning, are used as a measure of toxicity by narcosis. It is assumed that uptake by organisms takes place from the aqueous phase, and for partitioning, both oil droplets or coating and organic carbon of sediment are taken into account. To distinguish between the different fractions of TPH, the method used is based on a fraction analysis approach in which aliphatic and aromatic compounds are regarded separately and both are further divided into different fractions. A toxic unit approach is applied to these fractions to take additivity into account. Lethality of the lighter oil type (internal concentration 28–204 mmol/Llipid) was in good agreement with data on internal concentrations retrieved from the literature. For the heavier oil type the observed toxicity was slightly higher and can probably be attributed to physical soiling of the organisms by oil or oxygen depletion due to biodegradation of the oil. For deriving ERLs, chronic endpoints are considered. The most sensitive chronic endpoints appear to be similar for both types of oil. The distribution of estimated total internal concentrations for chronic endpoints (1.38–149 mmol/Llipid) is used as a basis for the ERLs. The resulting ERLs for the mixture of TPH are comparable with ERLs for single compounds.
Development of a new assay for evaluation of l-3,4-dihydroxyphenylalanine cytotoxicity in catalase-mutant Escherichia coli
Authors: Wang Da-Hong , Horita Masako , Tsutsui Ken , Sano Kuniaki , Sauriasari Rani , Masuoka Noriyoshi , Takemura Yoko , Takigawa Tomoko , Takaki Jiro , Ogino Keiki
Published: July 2008

The present study aimed to assess whether a newly constructed, catalase-deficient Escherichia coli strain that express mammalian catalase gene could be used to identify oxidative stress-generating chemicals. We tested L-3,4-dihydroxyphenylalanine (L-DOPA), a well-known agent that induces reactive oxygen species. We found that L-DOPA exposure reduced the survival of catalase-mutant E. coli in a dose-dependent manner, especially in the strains with lower catalase activities, implying the usefulness of these strains in assessment of oxidative chemicals.
Water-column concentrations and partitioning of polybrominated diphenyl ethers in the New York/New Jersey Harbor, USA
Authors: Zarnadze Archil , Rodenburg Lisa A
Published: July 2008

Despite the emerging concern regarding polybrominated diphenyl ethers (BDEs), very few measurements of BDE concentrations in ambient water have been published. In the present study, BDEs were measured in water samples from the New York/New Jersey Harbor (USA). Samples were taken in Raritan Bay west of Sandy Hook during four intensive sampling campaigns in 2000 and 2001. Congeners 17, 47, 99, 100, 153, 154, 183, and 209 were detected. Total BDE (σBDE) concentrations (average ± standard deviation) were 175 ± 75 ng/g in the particle phase and 110 ± 72 pg/L in the apparent dissolved phase. The deca-congener, BDE 209, constituted 85 and 9% of σBDEs in the particle and apparent dissolved phases, respectively. The σBDE levels are significantly higher than those measured in Lake Ontario, USA, and in The Netherlands, but they are similar to concentrations measured in Lake Michigan and San Francisco Bay (both USA). Calculated values of the organic carbon-water partition coefficient (KOC) were strongly correlated with literature values of the octanol-water partition coefficient (KOW). The data suggest that sorption of BDEs to colloids is important in this system, although quantifying the extent of colloid sorption is difficult.
Toxicodynamic assumptions in ecotoxicological hazard models
Authors: Ashauer Roman , Brown Colin D
Published: July 2008

Existing toxicokinetic and toxicodynamic models and dynamic formulations of popular ecotoxicological concepts (e.g., the critical body residue concept) are examined. Their underlying assumptions about speed of recovery and thresholds are clarified, and a rigorous mathematical treatment shows that they can all be placed within a unifying framework. Such analysis aids in the selection of appropriate ecotoxicological models.
Toxicity and metal speciation in acid mine drainage treated by passive bioreactors
Authors: Neculita Carmen-Mihaela , Vigneault Bernard , Zagury Gérald J
Published: July 2008

Sulfate-reducing passive bioreactors treat acid mine drainage (AMD) by increasing its pH and alkalinity and by removing metals as metal sulfide precipitates. In addition to discharge limits based on physicochemical parameters, however, treated effluent is required to be nontoxic. Acute and sublethal toxicity was assessed for effluent from 3.5-L column bioreactors filled with mixtures of natural organic carbon sources and operated at different hydraulic retention times (HRTs) for the treatment of a highly contaminated AMD. Effluent was first tested for acute (Daphnia magna and Oncorhynchus mykiss) and sublethal (Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Lemna minor) toxicity. Acute toxicity was observed for D. magna, and a toxicity identification evaluation (TIE) procedure was then performed to identify potential toxicants. Finally, metal speciation in the effluent was determined using ultrafiltration and geochemical modeling for the interpretation of the toxicity results. The 10-d HRT effluent was nonacutely lethal for O. mykiss but acutely lethal for D. magna. The toxicity to D. magna, however, was removed by 2 h of aeration, and the TIE procedure suggested iron as a cause of toxicity. Sublethal toxicity of the 10-d HRT effluent was observed for all test species, but it was reduced compared to the raw AMD and to a 7.3-d HRT effluent. Data regarding metal speciation indicated instability of both effluents during aeration and were consistent with the toxicity being caused by iron. Column bioreactors in operation for more than nine months efficiently improved the physicochemical quality of highly contaminated AMD at different HRTs. The present study, however, indicated that design of passive treatment should include sufficient HRT and posttreatment aeration to meet acute toxicity requirements.
Changes in morphology of the ground beetle Pterostichus oblongopunctatus F. (coleoptera; carabidae) from vicinities of a zinc and lead smelter
Authors: Lagisz Malgorzata
Published: July 2008

The present study investigated the response of the ground beetle Pterostichus oblongopunctatus F. (Coleoptera, Carabidae) to heavy metal pollution by assessing morphological traits (elytra length and wing length). Elytra length (a measure of body size) decreased with increasing pollution levels, whereas wing length (an indicator of flight dispersal ability) showed little change. The decrease in body size suggests negative effects of pollutants on the development and, subsequently, fitness of this species.
Effects of malathion on embryonic development and latent susceptibility to trematode parasites in ranid tadpoles
Authors: Budischak Sarah A , Belden Lisa K , Hopkins William A
Published: July 2008

We investigated the effects of embryonic exposure to the widely used organophosphate malathion (15–600 μg/L) on the early development and latent susceptibility of pickerel frog (Rana palustris) tadpoles to the trematode parasite Echinostoma trivolvis. The latent effects of contaminant exposure are rarely examined but could have important implications for individual survival and population viability. Malathion decreased hatching success by 6.5% and viability rates by 17% at 600 μg/L, which is a lower concentration than previously documented for anuran embryos. Incidence of malformations increased from 0.5% in controls to 11.2% in the 600-μg/L malathion treatment. The primary malformations documented in the two highest pesticide concentrations were ventralization and axial shortening. After seven weeks of development in water with no malathion, tadpoles previously exposed as embryos for only 96 h to 60 and 600 μg/L malathion suffered increased parasite encystment rates when compared to controls. Our research identifies embryonic development as a sensitive window for establishing latent susceptibility to infection in later developmental stages.
Sorption of polar and nonpolar aromatic compounds to two humic acids with varied structural heterogeneity
Authors: Sun Huiyu , Zhu Dongqiang , Mao Jingdong
Published: July 2008

The major objective of the present study was to evaluate the correlation between structural nature of humic acids (HAs) and sorption affinity of organic compounds with varied polarity. We compared the sorption behavior of three aromatic compounds—nonpolar phenanthrene (PHEN) and 1,2,4,5-tetrachlorobenzene (TeCB) and highly polar 2,4-dichlorophenol (DCP)—to a solid-phase coal humic acid (CHA) and a soil humic acid (SHA) suspended in aqueous solution. The structural nature of HAs was characterized using elemental analysis, ultraviolet absorbance, diffusive reflectance Fourier-transform infrared, and solid-state 13C nuclear magnetic resonance. The two tested HAs have very different structural properties: CHA consists primarily of poly(methylene)-rich aliphatics with high aromatic content and some COO/N–C=O but low polarity, while SHA consists of young materials of lignin, carbohydrates, and peptides with high polarity. In response to the structural heterogeneity of HAs, sorption of nonpolar and more hydrophobic solutes (PHEN, TeCB) to CHA is much greater than that to SHA because of the predominance of hydrophobic effects; however, disparities in sorption affinity between the two HAs become smaller for polar and less hydrophobic DCP because of the major role played by polar interactions. The influence of pH on the sorption of different solutes to the two HAs was also discussed. The results of the present work highlight the importance of structural heterogeneity of both solutes and HAs in the sorption process.
Scale-Corrected Ensemble Kalman Filtering Applied to Production-History Conditioning in Reservoir Evaluation
Authors: Lødøen O. P. , Omre H.
Published: July 2008

In reservoir evaluation problems, the reservoir properties are largely unknown. To infer these properties from observations of the reservoir production is referred to as history matching or production history conditioning. Traditionally, this is done by repeated fluid-flow simulations, where all the available production data are used simultaneously to arrive at a set of history-matched reservoir models. In recent years, the amount of data continuously collected from a reservoir under production has been on the increase. Hence, the need for automatic, continuous model updating is apparent. The ensemble Kalman filter has been shown to be suitable for this purpose. However, large reservoir evaluation problems require upscaling reservoir properties to perform the necessary number of fluid-flow simulations. Traditional ensemble Kalman filtering is shown to give bias in the production history conditioned reservoir representations. The loss in accuracy and precision introduced by performing fluid-flow simulations on a coarser scale should be accounted for, but this is rarely or never done. We introduce the scale-corrected ensemble Kalman filter approach in order to quantify the loss in accuracy and precision. A reference scale is defined and all uncertainty quantifications are made relative to this scale, although the fluid flow simulations are made on a coarser scale. The production history conditioned reservoir representation will be accurate with realistic precision measures on this reference scale. The methodology is demonstrated on a large case study inspired by the characteristics of the Troll field in the North Sea.
Modeling of Experiments on Water Vaporization for Gas Injection Using Traveling Waves
Authors: Zuluaga Elizabeth , Lake Larry W.
Published: July 2008

Dry gas injected into wells will vaporize water from near the wellbore. The vaporization starts from the well and proceeds outward. Gas flowing to producers is in equilibrium with the reservoir brine, but water will be vaporized because the pressure drop that occurs toward the wellbore increases the ability of the gas to contain water. Thus, there are different mechanisms for injection and production.

For both gas injection and gas production, vaporization concentrates solids in the brine that will precipitate into the formation when sufficiently concentrated. This paper reports on a combined experimental and theoretical analysis on the vaporization portion of this problem for dry gas injection.

Experiments have been performed previously to determine the rate of water vaporization from Berea core samples at uniform initial water saturation (Zuluaga and Monsalve 2003). These experiments were performed by injecting dry methane into core samples that contained immobile water to represent water vaporization in a gas injector.

Effluent water concentration curves showed two vaporization periods: a constant rate period and a falling rate period. The existence of a constant rate period means that the mass transfer within the core is occurring at conditions of local equilibrium. We interpret the falling rate period as the result of a moving capillary transition zone in which the amount of water vaporized decreases slowly because of capillary pressure effects. The falling rate period is the consequence of capillary imbibition of a wetting phase at very small saturation.

We interpret the vaporization results with two traveling wave solutions. The first, which can be solved analytically, assumes that the capillary diffusion coefficient, D, and the volume fraction of water in the gaseous phase, Cwg, are constant. For this case, the results of the traveling wave solution are matched to the results of laboratory experiments by adjusting D. The second traveling-wave solution must be solved through numerical integration. In this case, the relative permeability scaling exponent is adjusted to match the laboratory experiments. The fitting provides insights into the nature of wetting phase flow at small saturation. Lastly, the experimental and mathematical procedure discussed in this paper is certainly a new method to obtain relative permeability exponents for the wetting phase at very low values of wetting-phase saturation (down to theoretically zero values).
Reduction of Wellbore Effects on Gas Inflow Evaluation Under Underbalanced Conditions
Authors: Aremu O. J. , Osisanya S. O.
Published: July 2008

Wellbore storage effects have been identified to significantly smear the accuracy of evaluating reservoir productivity through the fluid outflow rate from the annulus during underbalanced drilling. Such effects have continuously introduced considerable errors in characterizing the reservoir during underbalanced drilling. Conceptually, because of the ready volume-changing ability of the gas, wellbore storage becomes a determining factor during underbalanced drilling of a gas reservoir. Wellbore storage could either cause decrease (unloading effects) or increase (loading effects) in the annular gas density, depending on the choke opening procedures. Correspondingly, annular fluid outflow rate is considerably affected. Because it is practically difficult to deduct the fluid-flow rate attributable to the wellbore storage from the total fluid outflow rate, reducing the influence of wellbore effects on the evaluation of gas-reservoir productivity is presented in this study. Volumetric production analysis at the wellbore-sand face is introduced through a mathematical modeling of inflow of gas bubbles into the wellbore. This mathematical modeling utilizes forces such as the viscous force, drilling fluid ejecting forces from the bit nozzles, buoyancy, interfacial tension, and gas-reservoir forces for its analyses. Some analytical results that are overshadowed by wellbore storage are presented and supported by extensive experimental studies.
Application of a New Grain-Based Reconstruction Algorithm to Microtomography Images for Quantitative Characterization and Flow Modeling
Authors: Thompson Karsten E. , Willson Clinton S. , White Christopher D. , Nyman Stephanie , Bhattacharya Janok P. , Reed Allen H.
Published: July 2008

X-ray computed microtomography (XMT) is used for high-resolution, nondestructive imaging and has been applied successfully to geologic media. Despite the potential of XMT to aid in formation evaluation, currently it is used mostly as a research tool. One factor preventing more widespread application of XMT technology is limited accessibility to microtomography beamlines. Another factor is that computational tools for quantitative image analysis have not kept pace with the imaging technology itself.

In this paper, we present a new grain-based algorithm used for network generation. The algorithm differs from other approaches because it uses the granular structure of the material as a template for creating the pore network rather than operating on the voxel set directly. With this algorithm, several advantages emerge: the algorithm is significantly faster computationally, less dependent on image resolution, and the network structure is tied to the fundamental granular structure of the material. In this paper, we present extensive validation of the algorithm using computer-generated packings. These analyses provide guidance on issues such as accuracy and voxel resolution. The algorithm is applied to two sandstone samples taken from different facies of the Frontier Formation in Wyoming, USA, and imaged using synchrotron XMT. Morphologic and flow-modeling results are presented.
Improving Petrophysical Interpretation With Wide-Band Electromagnetic Measurements
Authors: Toumelin Emmanuel , Torres-Verdín Carlos , Bona Nicola
Published: July 2008

Because of their sensitivity to ionic content and surface texture, wide-band electromagnetic (WBEM) measurements of saturated rocks exhibit frequency dispersions of electrical conductivity and dielectric constant that are influenced by a variety of petrophysical properties. Factors as diverse as fluid saturation, porosity, pore morphology, thin wetting films, and electrically charged clays affect the WBEM response of rocks. Traditional dielectric mixing laws fail to quantitatively and practically integrate these factors to quantify petrophysical information from WBEM measurements. This paper advances a numerical proof of concept for useful petrophysical WBEM measurements. A comprehensive pore-scale numerical framework is introduced that incorporates explicit geometrical distributions of grains, fluids and clays constructed from core pictures, and that reproduces the WBEM saturated-rock response on the entire kHz-GHz frequency range. WBEM measurements are verified to be primarily sensitive (a) in the kHz range to clay amounts and wettability; (b) in the MHz range to pore morphology (i.e., connectivity and eccentricity), fluid distribution, salinity, and clay presence; and (c) in the GHz range to porosity, pore morphology and fluid saturation. Our simulations emphasize the need to measure dielectric dispersion in the entire frequency spectrum to capture the complexity of the different polarization effects. In particular, it is crucial to accurately quantify the phenomena occurring in the MHz range where pore connectivity effects are confounded with clay polarization and pore/grain shape effects usually considered in dielectric phenomena. These different sensitivities suggest a strong complementarity between WBEM and NMR measurements for improved assessments of pore-size distribution, hydraulic permeability, wettability, and fluid saturation.
Multiscale Regularization of Flooding Optimization for Smart Field Management
Authors: Lien M. , Brouwer D. R. , Mannseth T. , Jansen J. D.
Published: July 2008

Smart fields can provide enhanced oil recovery through the combined use of optimization and data assimilation. In this paper, we focus on the dynamic optimization of injection and production rates during waterflooding. In particular, we use optimal control theory in order to find an optimal well management strategy over the life of the reservoir that maximizes an objective function (e.g., recovery or net present value). Optimal control requires the determination of a potentially large number of (groups of) well rates for a potentially large number of time periods. However, the optimal number of well groups and time steps is not known a priori. Moreover, taking these numbers too large can slow down the optimization process and increase the chance of achieving a suboptimal solution. We investigate the use of multiscale regulariza-tion methods to achieve grouping of the control settings of the wells in both space and time. Starting out with a very coarse grouping, the resolution is subsequently refined during the optimization. The regularization is adaptive in that the multiscale parameterization is chosen based on the gradients of the objective function. Results for the numerical examples studied indicate that the regularization may lead to significantly simpler optimum strategies, while resulting in a better or similar cumulative oil production.
Differential Grading Standards and Student Incentives
Authors: Eaton B. Curtis , Eswaran Mukesh
Published: July 2008

We present data on grades from three Canadian universities. These data suggest that grading standards differ significantly across disciplines within universities. To the extent that grading standards are not uniform across disciplines, the grade point averages (GPAs) of students with different course mixes cannot be meaningfully compared, and therefore their GPAs cannot legitimately be used to assess their relative achievement. Yet GPAs are used in precisely this way—to award scholarships, honours and degrees, and to ration access to courses, academic programs, and jobs. Hence, we think differential standards raise a fundamental issue of integrity for universities. We develop a simple human capital model to assess some of the distortions arising from differential standards and suggest some non-intrusive ways to rectify the problem.
Marketing Fun Foods: A Profile and Analysis of Supermarket Food Messages Targeted at Children
Authors: Elliott Charlene
Published: July 2008

Childhood obesity is a significant problem that requires innovative solutions. This article suggests that researchers and policy-makers move beyond a scrutiny of junk food and televised advertisements to children to focus on the messages targeted to children in the supermarket. Following a content analysis of fun foods marketed to children, the article (a) outlines why the recoding of “regular” food into “fun food” contributes to the childhood obesity crisis, and (b) suggests how the meaning-making practices of food can be acknowledged in the policy-making process.
Towards Sustainable Production of Biofuels from Microalgae
Authors: Patil Vishwanath , Tran Khanh-Quang , Giselrød Hans Ragnar
Published: July 2008

Renewable and carbon neutral biofuels are necessary for environmental and economic sustainability. The viability of the first generation biofuels production is however questionable because of the conflict with food supply. Microalgal biofuels are a viable alternative. The oil productivity of many microalgae exceeds the best producing oil crops. This paper aims to analyze and promote integration approaches for sustainable microalgal biofuel production to meet the energy and environmental needs of the society. The emphasis is on hydrothermal liquefaction technology for direct conversion of algal biomass to liquid fuel.
Low‐Dimensional Nanomaterials Based on Small Organic Molecules: Preparation and Optoelectronic Properties
Authors: Zhao Yong Sheng , Fu Hongbing , Peng Aidong , Ma Ying , Xiao Debao , Yao Jiannian
Published: July 2008

This article presents a comprehensive review of recent progress of research dedicated to low‐dimensional nanomaterials constructed from functional low‐molecular‐weight organic compounds, whose optoelectronic properties are fundamentally different from those of their inorganic counterparts. After introducing the development of inorganic and organic macromolecular nanomaterials, we begin with a general review of the construction strategies for achieving both zero‐dimensional (0D) and one‐dimensional (1D) nanostructures from small organic functional molecules. We then provide an overview of the unique optoelectronic properties induced by molecular aggregation in the nanostructures. Special emphasis is put on the luminescent properties that are different from those of the corresponding bulk materials, such as aggregation‐induced enhanced emission, fluorescence narrowing, multicolor emission, and tunable and switchable emissions from doped nanostructures. We conclude with a summary and our personal view of the direction of future development of organic opto‐functional nanomaterials and devices.
Conjugated Polymer Photovoltaic Materials with Broad Absorption Band and High Charge Carrier Mobility
Authors: Li Yongfang , Zou Yingping
Published: July 2008

Polymer solar cells (PSCs) have attracted great attention in recent years because of their advantages of easy fabrication, low cost, light weight, and potential for flexible devices. However, the power conversion efficiency (PCE) of the PSCs needs to be improved for future commercial applications. Factors limiting the PCE of the PSCs include the low exploitation of sunlight due to the narrow absorption band of conjugated polymers, and the low charge‐transport efficiency in the devices due to the lower charge‐carrier mobility of the polymer photovoltaic materials. In this Research News article, recent progress in new conjugated polymer photovoltaic materials fabricated by our group and others is reviewed, including polythiophene (PT) and poly(thienylene vinylene) derivatives with conjugated side chains for a broad absorption band, crosslinked PT derivatives with conjugated bridges for higher hole mobility, and low‐bandgap donor–acceptor copolymers for broad, red‐shifted absorption to match the solar spectrum.
Micrometer‐ and Nanometer‐Sized Organic Single‐Crystalline Transistors
Authors: Tang Qingxin , Jiang Lang , Tong Yanhong , Li Hongxiang , Liu Yaling , Wang Zhaohui , Hu Wenping , Liu Yunqi , Zhu Daoben
Published: July 2008

The use of micrometer and nanometer‐sized organic single crystals to fabricate devices can retain all the advantages of single crystals, avoid the difficulties of growing large crystals, and provide a way to characterize organic semiconductors more efficiently. Moreover, the effective use of such “small” crystals will be beneficial to nanoelectronics. Here we review the recent progress of organic single‐crystalline transistors based on micro‐/nanometer‐sized structures, namely fabrication methods and related technical issues, device properties, and current challenges.
Rational Functionalization of Carbon Nanotubes Leading to Electrochemical Devices with Striking Applications
Authors: Yan Jie , Zhou Haojie , Yu Ping , Su Lei , Mao Lanqun
Published: July 2008

As one‐dimensional carbon nanostructures, carbon nanotubes (CNTs) are a member of the carbon family but they possess very different structural and electronic properties from other kinds of carbon materials frequently used in electrochemistry, such as glassy carbon, graphite, and diamond. Although the past decade has witnessed rapid and substantial progress in both the fundamental understanding of CNT‐oriented electrochemistry and the development of various kinds of electrochemical devices with carbon nanotubes, the increasing demand from both academia and industry requires CNT‐based electrochemical devices with vastly improved properties, such as good reliability and durability, and high performance. As we outline here, the smart functionalization of CNTs and effective methods for the preparation of devices would pave the way to CNT‐based electronic devices with striking applications.
Demonstration of loop reactor operation
Authors: Madai A. Y. , Sheintuch M.
Published: July 2008

This article is the first experimental demonstration of autothermal operation in an open loop reactor for catalytic abatement of low‐concentration volatile organic compounds (VOC). The system under investigation, which comprises three reactors organized in a loop with automatic switching of the feed position, has been successfully operated for ethylene oxidation. The influence of the feed flow rate and concentration on the pulse velocity and maximal temperature has been investigated. A simple analytical approximation for front velocity in the nonadiabatic one‐dimensional (1D) model has been derived and compared with the experimental results. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Optical Rotation of Achiral Compounds
Authors: Claborn Kacey , Isborn Christine , Kaminsky Werner , Kahr Bart
Published: July 2008

Oriented achiral molecules and crystals with D2d symmetry or one of its non‐enantiomorphous subgroups, S4, C2v, or Cs, can rotate the plane of transmitted polarized light incident in a general direction. This well‐established fact of crystal optics is contrary to the teaching of optical activity to students of organic chemistry. This Minireview gives an overview of the measurement and calculation of the chiroptical properties of some achiral compounds and crystals. Methane derivatives with four identical ligands related by reflection symmetry are quintessential optically inactive compounds according to the logic of van't Hoff. Analysis of the optical activity of simple achiral compounds such as H2O and NH3 provides general aspects of chiroptics that are not readily broached when considering chiral compounds exclusively. We show here, through the use of group theoretical arguments, the transformation properties of tensors, and diagrams, why some achiral, acentric compounds are optically active while others are not.
Origin and Endpoint of the Olfactory Nerve Fibers: As Described by Santiago Ramón y Cajal
Authors: Levine Catherine , Marcillo Alexander
Published: July 2008

Illustration by author Catherine Levine inspired by the original drawing by Santiago Ramón y Cajal, featured in the article Origin and endpoint of the olfactory nerve fibers: As described by Santiago Ramón y Cajal. Depicted are large tufted cells and granule cells, a large stellate cell, a row of mitral cells and the arborization on the olfactory glomeruli, with olfactory nerve fibers streaming through the cartilage formation of the cribriform plate. See Levine et al., Anatomical Record 291:741–750.
Cloning and characterization of Bmrunt from the silkworm Bombyx mori during embryonic development
Authors: Liu Wenbin , Yang Fei , Jia Shihai , Miao Xuexia , Huang Yongping
Published: July 2008

Pair‐rule genes (genes that are expressed only in alternate segments, odd or even) play an important role in translating the broad gradients of upstream genes into dual segment periodicity for body plan patterning in Drosophila. However, homologues of pair‐rule genes show a remarkable diversity of expression patterns and functions in other insects. We cloned the homologue of runt in the silkworm Bombyx mori, an intermediate germband‐type insect. Whole‐mount in situ hybridization revealed three stripes arose one by one before gastrulation at the blastoderm stage. Five additional stripes were then generated sequentially as the growth zone elongated. Eight stripes appeared in a pair‐rule manner with two‐segment periodicity, each of which was confined to the posterior of an odd‐numbered parasegment. The weaker segmental secondary stripes emerged de novo in even‐numbered parasegments. The Bmrunt transcript vanished before blastokinesis and was then expressed again in the whole embryo. RNA interference for Bmrunt caused severely truncated, almost completely asegmental defects. This cadual‐like phenotype suggests that Bmrunt does not function as a pair‐rule gene in silkworm segmentation. Bmrunt is required for formation of most body segments and axis elongation in B. mori. Arch. Insect Biochem. Physiol. 2008. © 2008 Wiley‐Liss, Inc.
Monoterpenoid Indole Alkaloids Bearing an N4‐Iridoid from Gelsemium elegans
Authors: Yin Sheng , He Xiu‐Feng , Wu Yan , Yue Jian‐Min
Published: July 2008

Five new alkaloids, gelseganines A–D (1–4) and humantenine N4‐oxide (5), were isolated from the stems and leaves of Gelsemium elegans. Compounds 1–4 represent a rare class of monoterpenoid indole alkaloids that bear an N4‐iridoid unit. The structures of 1–5 were determined by spectroscopic analysis, single‐crystal X‐ray diffraction, and chemical correlation, and their absolute configurations were elucidated by CD analysis. A plausible biogenetic pathway for alkaloids 1–5 was also postulated.
Stereoselective Synthesis of (−)‐Amphidinolide E
Authors: Kim Chan Hyuk , An Hyo Jung , Shin Won Kyo , Yu Wei , Woo Sang Kook , Jung Soon Kyu , Lee Eun
Published: July 2008

The total synthesis of (−)‐amphidinolide E was accomplished by following a synthetic scheme that incorporates the labile C2 stereocenter at a very late stage. The oxolane unit was prepared by β‐alkoxyacrylate radical cyclization. The enyne metathesis reaction was employed for the synthesis of the side chain. The Kocienski–Julia reaction was used for the union of the two major fragments, and the Kita macrolactonization protocol was used for macrolide synthesis.
Enantiomerically Pure Titanium Complexes Containing an [OSSO]‐Type Bis(phenolate) Ligand: Synthesis, Structure, and Formation of Optically Active Oligostyrenes
Authors: Meppelder Geert‐Jan M. , Beckerle Klaus , Manivannan Ramanujachary , Lian Bing , Raabe Gerhard , Spaniol Thomas P. , Okuda Jun
Published: July 2008

Chiral 1,2‐trans‐dithiocyclohexanediyl‐bridged bis(phenols) of the type [2,2′‐{HOC6H2‐6‐R1‐4‐R2}2S2C6H10] ([OSSO]H2, R1=tBu, iPr, H; R2=tBu, iPr, Me) could be conveniently and selectively synthesized in three steps, starting from cyclohexene oxide and arene thiolate. The racemic bis(phenols) could be resolved using an enantiopure (S)‐camphorsulfonic ester auxiliary or by (chiral) HPLC. Complexation of the racemic bis(phenols) to TiX4 (X=Cl, OiPr) proceeds in a diastereoselective fashion to give only the Λ,R,R and Δ,S,S enantiomers. Racemic [Ti{(OC6H2‐6‐tBu‐4‐Me)2S2C6H10}Cl2] reacts with benzyl magnesium bromide to afford the crystallographically characterized dibenzyl complex. The benzyl cation formed using B(C6F5)3 in C6D5Br slowly decomposes at temperatures above +10 °C. When treated with methylaluminoxane, the dichloro complexes [Ti{OSSO}Cl2] polymerize styrene with activities up to 146 kg (mol catalyst)−1 [styrene (mol L−1)]−1 h−1; diisopropoxy complexes [Ti{OSSO}(OiPr)2] show mere trace activity. With 1‐hexene as a chain‐transfer agent, activated enantiopure titanium complexes give low‐molecular‐weight homochiral isotactic oligostyrenes, terminated by one to five 1‐hexene units with Mn values as low as 750 g mol−1 for R=tBu and 1290 g mol−1 for R=Me. Below Mn≈5000 these oligostyrenes show optical activity.
Synthesis of Bifunctional Imido Alkylidene BisPyrrolide Complexes of Molybdenum and Their Conversion into Bifunctional Imido Alkylidene Diolate Complexes That Can Be Employed as ROMP Initiators
Authors: Gabert Andrea J. , Schrock Richard R. , Müller Peter
Published: July 2008

Addition of four equivalents of lithium 2,5‐dimethylpyrrolide to a solution of [Mo(NAr)(ORF6)2(CHC5H4)]2Fe (ORF6=OCMe(CF3)2) in dichloromethane led to [Mo(NAr)(Me2Pyr)2(CHC5H4)]2Fe (2; Me2Pyr=2,5‐dimethylpyrrolide) and lithium hexafluoro‐tert‐butoxide, which crystallizes out upon cooling the reaction mixture to −35 °C. Attempts to prepare parent pyrrolide complexes analogous to 2 resulted in the formation of a mixture of two products. The one that could be isolated contains one equivalent of lithium pyrrolide per molybdenum, that is [Mo(NAr)(Pyr)3(CHC5H4)]2FeLi2 (3). The X‐ray structure obtained shows it to be a dimer of dimers in which each lithium atom is bound to three pyrrolides. Addition of four equivalents of lithium 2,5‐dimethylpyrrolide to [Mo(NAr)(ORF6)2]2(DME)2(CH‐1,4‐C6H4CH) (1 b) in cold DME produced [Mo(NAr)(Me2Pyr)2]2(CH‐1,4‐C6H4CH) (4) in good yield, in which the bridging alkylidene is derived from 1,4‐divinylbenzene. Three equivalents of (S)‐H2[Biphen] are required for a clean reaction with 3 to form [Mo(NAr)(Biphen)(CHC5H4)]2Fe (5) (H2[Biphen]=3,3′‐di‐tert‐butyl‐5,5′,6,6′‐tetramethyl‐1,1′‐biphenyl‐2,2′‐diol), Li2[Biphen], and two equivalents of pyrrole. Reactions involving 4 with the chiral diols are the best behaved. Brown [Mo(NAr)(Benz2Bitet)]2(CH‐1,4‐C6H4CH) (6) can be isolated upon addition of (R)‐H2[Benz2Bitet] (H2[Benz2Bitet]=(3,3′‐dibenzhydryl‐5,5′,6,6′,7,7′,8,8′‐octahydro‐1,1′‐binaphthyl‐2,2′‐diol) to 4, while addition of (R)‐H2[Mes2Bitet] (H2[Mes2Bitet]=3,3′‐dimesityl‐5,5′,6,6′,7,7′,8,8′‐octahydro‐1,1′‐binaphthyl‐2,2′‐diol) to 4 yields [Mo(NAr)(Mes2Bitet)]2(CH‐1,4‐C6H4CH) (7). Compounds 5, 6, and 7 were employed as initiators for the polymerization of 2,3‐dicarbomethoxynorbornadiene (DCMNBD) and 2,3‐bis(trifluoromethyl)norbornadiene (NBDF6).
Microflow System Controlled Carbocationic Polymerization of Vinyl Ethers
Authors: Nagaki Aiichiro , Iwasaki Takeshi , Kawamura Kohsuke , Yamada Daisuke , Suga Seiji , Ando Tuyoshi , Sawamoto Mitsuo , Yoshida Jun‐ichi
Published: July 2008

A “cation pool” of an N‐ acyliminium ion was found to serve as an effective initiator of cationic polymerization of vinyl ethers in a microflow system consisting of two micromixers (IMM micromixer) and two microtube reactors. The cationic polymerization of n‐butyl vinyl ether in CH2Cl2 at −78 °C led to very narrow molecular weight distribution (Mw/Mn=1.14). The molecular weight (Mn) increased linearly with an increase in monomer/initiator ratio. The carbocationic polymer end was effectively trapped by allyltrimethylsilane. Additionally, the synthesis of block polymers was accomplished by the present microflow system controlled method. The polymerization was also conducted using commercially available trifluoromethanesulfonic acid (TfOH) as an initiator. A high level of molecular weight control was attained even at −25 °C. The TfOH‐initiated polymerization could be conducted using a microflow system based on T‐shaped micromixers, which serves as a practical tool for microflow system controlled carbocationic polymerization.
Fullerene‐like Mo(W)1−xRexS2 Nanoparticles
Authors: Deepak Francis Leonard , Popovitz‐Biro Ronit , Feldman Yishay , Cohen Hagai , Enyashin Andrey , Seifert Gotthard , Tenne Reshef
Published: July 2008

Inorganic fullerene‐like (IF) Mo1−xRexS2 and W1−xRexS2 nanoparticles have been synthesized by a gas‐phase reaction involving the respective metal halides with H2S. The IF‐Mo(W)1−xRexS2 nanoparticles, containing up to 5 % Re, were characterized by a variety of experimental techniques. Analyses of the X‐ray powder diffraction and different electron microscopy techniques show that the Re is doped in the MoS2 host lattice. Interestingly, Re‐doped MoS2 nanotubes are present as well, although in small quantities (∼5 %). XPS results confirm the nanoparticles to be more n‐type arising from the effect of Re doping. Additionally, density‐functional tight‐binding (DFTB) calculations support the observed n‐type behavior.