bluuebunny/crossref_metadata_2025 huggingface dataset:
Reactivity Studies on 2,3,4,5‐Tetraethyl‐1,6‐diiodo‐2,3,4,5‐tetracarba‐nido‐hexaborane(6): Synthesis and Structures of New C4B2nido‐Carborane Derivatives
Authors: Nie Yong , Pritzkow Hans , Siebert Walter
Published: April 2004

The reactivity of the title compound 2,3,4,5‐tetraethyl‐1,6‐diiodo‐2,3,4,5‐tetracarba‐nido‐hexaborane(6) (1) towards a variety of nucleophiles is reported. When 1 is treated with RC2Li (R = Ph, tBu, SiMe3, p‐tolyl) and Ph2PLi, the corresponding new C4B2 nido‐carborane derivatives 2a−d and 3, respectively, are obtained by selective substitution at the basal B−I group, whereas the apical B−I bond remains inert. The reaction of 1 with K[(η5‐C5H5)Fe(CO)2] affords the novel species 4, which contains a CpFe(CO)2 fragment σ‐bonded to the basal boron atom of the C4B2 cluster. Attempts to isolate 4 by chromatography on silica gel led to cleavage of the Fe−B bond and formation of compound 5, containing a basal BH vertex, which can be separately prepared by the reaction of 1 and LiBEt3H. In the reactions of 1 with PhLi and Me3SnLi, respectively, 6a and 7a are formed as the predominant B6‐substituted carborane products. In addition, trace amounts of 1,6‐disubstituted species 6b and 7b are also detected. The substitution at the apical B−I group in 2a with an alkynyl group is effected by a Pd0‐catalyzed Negishi‐type cross‐coupling reaction to give compound 8. The reaction of 1 and monolithio‐o‐carborane affords the C4B2−C2B10 carborane 10, while the reaction of 2a and Co2(CO)8 furnishes the double cluster 9 (C4B2−C2Co2). In both 9 and 10 two different types of clusters are directly connected by a B−C bond. Compound 1 reacts with ClZnC6H4C6H4ZnCl in the presence of the catalyst Pd(PPh3)4 to give 11, in which two C4B2 clusters are linked by a C6H4C6H4 unit. The constitutions of the products follow from spectroscopic data, and X‐ray diffraction analyses for 2a, 2d, 4, 8, 9, and 10. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Electronic Structure of Transition Metal−Isocorrole Complexes: A First Quantum Chemical Study
Authors: van Oort Bart , Tangen Espen , Ghosh Abhik
Published: April 2004

DFT calculations indicate that the broad electronic‐structural features of metalloisocorroles are rather similar to those of analogous metallocorroles. Thus, like their corrole analogues, many metalloisocorroles feature substantially non‐innocent ligands. Another key point is that both corroles and isocorroles can exhibit at least two kinds of radical character, a2 and b1. However, corrole and isocorrole derivatives also differ significantly in a few ways: for example, the S = 1/2 CoPh complexes of corrole and isocorrole exhibit ground states of different symmetries (2A′′ and 2A′, respectively, in Cs notation), reflecting different interplays of metal(dπ)−ligand(pπ) interactions in corrole versus isocorrole derivatives. The ligand non‐innocence phenomena encountered in this study are broadly reminiscent of similar phenomena in peroxidase compound I intermediates and their synthetic models. It seems reasonable, therefore, to adopt the view that this study, along with related studies on corrole derivatives, provides a broader chemical context for appreciating the electronic structures of high‐valent heme protein intermediates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A treatment process for removal of mixed inorganic and organic arsenic species from groundwater
Authors: Banerjee Kashi , Helwick Robert P. , Gupta Satish
Published: April 2004

A process was developed to treat contaminated groundwater containing mixed inorganic and organic arsenic to less than the current U.S. drinking water standard of < 50 μg/L. The treatment efficiency of the process was investigated under various operating conditions. Samples were analyzed using the Inductively Coupled Plasma (ICP) method and the Graphite Furnace Atomic Absorption Spectrometric method. Species present in the contaminated water included arsenic (III), arsenic (V), and organic arsenic compounds. Fenton's reagent was used as the oxidizing agent in the treatment process. To define the design parameter s for the process, the bench‐scale study addressed: (1) the amount of iron required to achieve a soluble arsenic concentration of < 50 μg/L in the treated effluent, (2) the amount of hydrogen peroxide required during the oxidation process, (3) the effect of pH, and (4) the required reaction time. The results revealed that each of the above operating parameters have a significant effect on the treatment efficiency. To achieve a soluble arsenic concentration of < 50 μg/L, an iron to arsenic weight ratio of 10 to 1 is required for this type of groundwater. The data also revealed that as the dosage of hydrogen peroxide increased, the concentration of soluble arsenic in the treated effluent decreased until a hydrogen peroxide to iron weight ratio of 1 to 2 was reached. Maximum treatment efficiency was obtained at a pH between 2.5 and 3.0 Standard Units (S.U.). More than 99 percent of the arsenic was removed from the sample within the first five minutes of the reaction.
What is life cycle interpretation?
Authors: Skone Timothy J.
Published: April 2004

Life Cycle Interpretation “is a systematic technique to identify, quantify, check, and evaluate information from the results of the life cycle inventory(LCI) and/or the life cycle impact assessment (LCIA)…”[1] The purpose of performing life cycle interpretation is to determine the level of confidence in the final results and communicate them in a fair, complete, and accurate manner.

Interpreting the results of a life cycle assessment (LCA) is not as simple as 3 is better then 2, therefore Alternative A is the best choice! Interpreting the results of an LCA starts with understanding the accuracy of the results, and ensuring they meet the goal of the study. This is accomplished by identifying the data elements that contribute significantly to each impact category, evaluating the sensitivity of these significant data elements, assessing the completeness & consistency of the study, and drawing conclusions and recommendations based on a clear understanding of how the LCA was conducted and the results we re developed.

The guidance provided in this article builds from the information provided on life cycle interpretation in the International Organization of Standard's (ISO's) draft standard entitled “Environmental Management ‐Life Cycle Assessment ‐ Life Cycle Interpretation,” ISO/DIS 14043.
Meeting the great lakes water discharge challenge: A case study
Authors: Lee Vail R.
Published: April 2004

Early in the 1990s, the Wisconsin Department of Natural Resources (WDNR) developed a draft permit for the Murphy Oil refinery in Superior that contained water quality limits reflective of the anticipated “Great Lakes Initiative.” However, not enough was known about the quality of the existing effluent generated by the facility to determine the refinery's compliance potential with the new permit. Further, available literature, although extensive for removal rates for general parameters, was silent on expected levels and removal rates of specific contaminates, like metals, at such low concentrations. After collecting extensive source and effluent data, the company decided that the refinery needed to replace its existing pond treatment system with an activated sludge‐based treatment system. This paper describes and compares pilot testing results to actual results from the new wastewater treatment plant, particularly those that relate to critical parameters, such as the low concentrations of metal.
New membrane technology for removal and recovery of chromium from waste waters
Authors: Ho W. S. Winston , Poddar Tarun K.
Published: April 2004

We have developed new supported liquid membrane (SLM) technology for removal and recovery of chromium from waste waters. The technology not only removes the Cr (VI) to less than 0.05 ppm in the treated effluent allowable for discharge or recycle, but also recovers the product at a high concentration of about 20% (62.3% Na2CrO4) suitable for resale or reuse. In other words, we have achieved the goals of zero discharge and no sludge. The chromium flux in its entire range from low Cr (VI) concentrations in the feed solution to high feed concentrations, at which the carrier saturation of the facilitated transport mechanism occurs, has been in good agreement with a film model. The stability of the SLM has been ensured by strip dispersion, where the aqueous strip solution is dispersed in the organic membrane solution in a mixer. The strip dispersion formed is circulated from the mixer to the membrane module providing a constant supply of the organic solution to the membrane pores.
Odor investigation and control at a WWTP in orange county, florida
Authors: Cooper C. David , Godlewski Victor J. , Hanson Ray , Koletzke Mark , Webster Neil
Published: April 2004

Due to occasional complaints of odors from residential and commercial neighbors, and the projected development of adjacent vacant land, an investigation was conducted at a county wastewater treatment plant (WWTP) Utilizing a physical survey of possible odor sources, an emissions measurement study, and dispersion modeling, the site was assessed for current and future odor impacts. The main compound contributing to odors was concluded to be hydrogen sulfide (H2S). Using the EPA dispersion model Industrial Source Complex Short Term (ISCST3) and ten years of meteorological data, the H2S emissions results were analyzed to estimate potential maximum H2S concentrations, as well as the annual frequency of occurrences of H2S above certain concentrations. The chief source of odor impacts was identified as fugitive emissions from the top of the grit chamber/flow splitter building, through openings for valve stems, flow gates, and the grit removal conveyor apparatus. Another ventilation fan was added, and the H2S‐laden air from the building was routed through new biofiltration units, which were being evaluated to replace an older caustic/chlorine scrubber. Since these units operated at an extremely high H2S removal efficiency, it was concluded that biofilters would replace caustic/chlorine scrubbing on a permanent basis.
Biofiltration of air loaded with ammonia by granulated sludge
Authors: Gracian C. , Malhautier L. , Fanlo J. L. , Le Cloirec P.
Published: April 2004

Granulated sludge has some physico‐chemical characteristics that make it useful as a packing material in biofilters. The purpose of this study was to investigate the potential of a biofiltration unit packed with this support material to treat ammonia. The results show that ammonia elimination is very high. The maximum removal efficiency at a volumetric load of 140 and 300 g ammonia.m−3 packing.day−1 is 90% and 80%, respectively. The use of sludge requires neither nutritive aqueous solution, nor buffer solution, as was the case for other treatment systems. Subject to adequate humidification, the pressure drops measured were very low. Ammonia was oxidized to nitrite, nitrate, and probably gaseous nitrogen, the proportions of each depending on operating conditions of the biofilter. For ammonia concentrations below 576 g ammonia.m−3 packing.day−1, ammonia removal in biofilters packed with sludge followed apparent first order kinetics. The maximum growth rates estimated by the theoretical model and experimental results are slightly superior to those found for pure cultures. The operating conditions would seem to be more favorable to nitrifying bacteria growth. These results also show the complex phenomena which govern ammonia removal in biofilters.
Supercritical fluid extraction process for removing polychlorinated biphenyl from a DOE job control waste
Authors: Li Jun , Davis Thomas A. , Matthews Michael A.
Published: April 2004

A supercritical carbon dioxide process has been investigated for remediation of polychlorinated biphenyl (PCB) contaminated Job Control Wastes at DOE sites. A PCB surrogate, 2‐chlorobiphenyl, was spiked into Toxi‐dry, a commercial absorbent material used extensively for decontaminating and decommissioning at DOE sites. Supercritical carbon dioxide extraction of 2‐chlorobiphenyl from Toxi‐dry was conducted with pure or ethanol‐modified carbon dioxide in bench‐scale units. Extraction temperatures, pressures, and time were varied to identify favorable operating conditions, and the effects of cosolvent and extraction time on supercritical extraction of PCBs were also investigated. About 95% of 2‐chlorobiphenyl was extracted from Toxi‐dry by CO2 modified with 5% EtOH, compared to just 53% with pure CO2 at the same pressure and temperature. While increasing temperature from 40°C to 80°C showed a clear improvement on extraction, increasing pressure from 2,000 psi to 4,000 psi does not significantly improve extraction efficiencies. Increasing extraction time from 2 hours to 3 hours does not increase the removal efficiency. The results demonstrate the potential of modified supercritical CO2 extraction as a PCB extraction technology for DOE PCB‐contaminated Toxi‐dry.
Influence of nitrogen supply and substrate interactions on the removal of paint VOC mixtures in a hybrid bioreactor
Authors: Song Jihyeon , Kinney Kerry A. , John Paul
Published: April 2004

The study presented here was designed to investigate VOC degradation patterns as a function of nitrogen availability in a hybrid vapor‐phase bioreactor column treating a surrogate paint VOC mixture. The mixture consisted of methyl propyl ketone, ethyl 3‐ethoxy propionate, n‐butyl acetate, toluene and p‐xylene. In order to quantify nitrogen requirements, a series of experiments was conducted under various nitrogen‐limited and nitrogen‐rich conditions. Overall, increasing nitrogen availability improved the total VOC removal efficiencies from approximately 70% to 99%. At the lowest available nitrogen condition, most of the ethyl 3‐ethoxy propionate and n‐butyl acetate, as well as approximately 75% of the methyl propyl ketone were removed in the bioreactor, but toluene and p‐xylene were not biodegraded. Increasing the nitrogen availability improved the biodegradation of methyl propyl ketone. Substantial degradation of toluene and p‐xylene occurred in this study only after the molar ratio of the aromatic compounds to the other constituents in the waste gas stream increased above 2.0. Elimination capacity tests performed with the VOC mixture and each individual VOC indicated that the presence of other VOCs inhibited the biodegradation of toluene and p‐xylene. These findings imply that substrate inhibitions limit the removal of aromatic hydrocarbons, particularly when the available nitrogen in the packing media is low.
Hydrogen sulfide (H2S) removal in synthetic media biofilters
Authors: Shareefdeen Zarook , Herner Brian , Webb Derek , Wilson Steve
Published: April 2004

This paper reviews recent developments in biofiltration as a process for the removal of hydrogen sulfide (H2S) from contaminated air using synthetic media. The paper includes results of extensive research, as well as data collected from a commercial biofilter installation at a municipal wastewater pumping station in Ontario, Canada. The results indicate that, for H2S concentrations of up to 40 ppm inlet, only 30‐second empty bed residence time (EBRT) is required. But, for lower concentrations (< 12 ppm), 20‐second EBRT is sufficient for complete elimination of H2S from airstreams using a synthetic media biofilter. The collected data shows that varying concentrations and flow, resulting in shock‐loading conditions, can be easily handled by a biofilter containing synthetic media. Furthermore, results show that biofilters can be operated underlow (∼2.0) and neutral pH conditions without introducing buffering chemicals into the media. Based on this research data, biofilters are designed and sold for a wide range of applications requiring removal of nuisance H2S compound from industrial and municipal air streams.
Journey towards sustainable development: A role for chemical engineers
Authors: Sikdar Subhas K.
Published: April 2004

Since the publication of the report entitled, Our Common Future, under the auspices of the World Commission on Environment and Development (WCED), also known as the Brundtland Commission, it has been generally acknowledged that the increasing use of non‐renewable resources to support an increasing population has created an unsustainable situation. Should this rate of use be maintained, two dire consequences will follow: first, the future generations will be unable to maintain a high standard of living, and second, developing countries will have less of an opportunity to bring their living standards to a level comparable to that of the affluent West. The practice of chemical engineering, perhaps more than any other technical discipline, involves the use of natural material and energy resources for the production of value‐added articles and services of commerce, It is critically important that chemists and chemical engineers incorporate the ideas of sustainability into process and product design, manufacturing, and value chain management for the purpose of minimizing resource utilization and adverse environmental impact. This paper deals with the ideas of sustainability, and what chemists and chemical engineers can do to prevent the consequences of unsustainable resource utilization.
Differential rAAV2 transduction efficiencies and insulin secretion profiles in pure and co‐culture models of human enteroendocrine L‐cells and enterocytes
Authors: Tang Shiue‐Cheng , Sambanis Athanassios
Published: April 2004

Background

Cell‐based therapies for treating insulin‐dependent diabetes (IDD) can provide a more physiologic regulation of blood glucose levels in a less invasive fashion than insulin injections. Previously, we developed an engineered human enteroendocrine L‐cell model for regulated insulin release via recombinant adeno‐associated virus serotype 2, or rAAV2, transduction. The aim of this study was to evaluate the efficiency and selectivity of rAAV2‐mediated insulin gene delivery to enteroendocrine L‐cells in co‐culture with a prevailing number of enterocytes, which are the predominant cell type in intestinal epithelium.

Methods

We tested rAAV2 transduction in pure and co‐culture models of human cell lines of enterocytes (Caco‐2 and T84 cell lines) and enteroendocrine L‐cells (NCI‐H716 cell line). Non‐viral, chemical‐mediated transfection was used as a control. Transduced and transfected co‐cultures were subjected to insulin secretion studies.

Results

In pure cultures, rAAV2 exhibited a low transduction efficiency towards both Caco‐2 and T84 enterocytes, as opposed to a strong reporter expression in permissive NCI‐H716 L‐cells. In co‐cultures of NCI‐H716 L‐cells and Caco‐2 or T84 enterocytes, rAAV2 exhibited differential transduction efficiency with a strong preference towards NCI‐H716 L‐cells. The rAAV2‐transduced co‐culture achieved regulated insulin release against stimulation, whereas the chemically transfected co‐culture failed to respond.

Conclusions

This study demonstrated that rAAV2‐mediated insulin gene transfer can differentiate human intestinal cell types in vitro, in particular enterocyte and enteroendocrine L‐cell lines. We consider the AAV2 vector a useful tool in developing enteroendocrine L‐cell‐specific insulin gene delivery for IDD treatment, in terms of AAV2 avoiding enterocytes and targeting selectively L‐cells. Copyright © 2004 John Wiley & Sons, Ltd.
Sleep‐wake states and cortical synchronization control by pregnenolone sulfate into the pedunculopontine nucleus
Authors: Darbra Sonia , George Olivier , Bouyer Jean‐Jacques , Piazza Pier‐Vincenzo , Le Moal Michel , Mayo Willy
Published: April 2004

Cholinergic neurons of the pedunculopontine tegmentum nucleus (PPT) are crucial for initiation and maintenance of electroencephalographic (EEG) desynchronization states like paradoxical sleep and wakefulness. These neurons are regulated by classical neurotransmitter systems from the pontomesencephalic reticular formation and basal ganglia. In addition to this regulation, PPT neuron activity could be modulated by endogenous neurosteroids and particularly by pregnenolone sulfate (PREG‐S) because synthesis enzymes of this neurosteroid are present in this area and peripheral administrations of PREG‐S affect sleep‐wakefulness states. To test this hypothesis, we studied the effects of different doses of PREG‐S infusion into the PPT on sleep‐wakefulness states in rats. Our results show dose‐dependent effects of PREG‐S on sleep‐wakefulness states. Low concentration of PREG‐S (5 ng) increased the amount of paradoxical sleep without any modification of slow wave sleep and wakefulness. High level of PREG‐S (10 and 20 ng) increased paradoxical sleep and slow wave sleep together with an increase of delta power and a decrease of theta power during wakefulness. Dependent on the doses used, PREG‐S thus can promote paradoxical sleep alone or the global propensity to fall asleep, impairing the quality of wakefulness. These results unveil a new regulation pathway for PPT neurons and strengthen the role of PREG‐S in sleep‐wakefulness regulation. © 2004 Wiley‐Liss, Inc.
Polyol‐Metall‐Komplexe. 491)μ‐Dulcitolato‐O2, 3;4, 5‐Komplexe mit Amin‐Kupfer(II)‐ und ‐Nickel(II)‐Metallfragmenten
Authors: Herdin Sven , Klüfers Peter , Kunte Thomas , Piotrowski Holger
Published: April 2004

Der zweikernige Ethylendiamin‐kupfer(II)‐Komplex des Tetraanions des achiralen Alditols Dulcit (Galactit) ist als erster kristallin erhaltener Kohlenhydrat‐Metall‐Komplex bemerkenswert (W. Traube, G. Glaubitt, V. Schenck, Ber. Dtsch. Chem. Ges. 1930, 63, 2083—2093). Obwohl seit Jahrzehnten bekannt, blieb seine Struktur aufgrund eines Kristallaufbaus, der die Bildung von Zwillingsdomänen fördert, unbekannt. Kristallisation bei niedriger Temperatur ergab nun kristalline Proben von [(en)2Cu2(Dulc2, 3, 4, 5H—4)] · 7 H2O (1), die sowohl die Strukturanalyse als auch die Untersuchung der Zwillingsbildung erlaubten. Verwandte Komplexstrukturen liegen in [(tren)2Ni2(Dulc2, 3, 4, 5H—4)] · 20 H2O (2) und [(Me3tren)2Ni2(Dulc2, 3, 4, 5H—4)] · 16 H2O (3) vor. 3 enthält mit einem O···O‐Abstand von 2.422Å die kürzeste Wasserstoffbrückenbindung, die bislang bei einem Polyolat‐Akzeptor gefunden wurde.
Mesozoic mammals and early mammalian brain diversity
Authors: Gilissen Emmanuel , Smith Thierry
Published: April 2004

Fossil remains witness the relationship between the appearance of the middle ear and the expansion of the brain in early mammals. Nevertheless, the lack of detachment of ear ossicles in the mammaliaform Morganucodon, despite brain enlargement, points to other factors that triggered brain expansion in early mammals. Moreover, brain expansion in some early mammalian groups seems to have favored brain regions other than the cortex.
The dorsal thalamic connection in the origin of the isocortex
Authors: Guirado Salvador
Published: April 2004

The origin of the isocortex may be seen as a series of gradual changes (each one with an adaptive value) from a reptilian-like cerebral cortex, as proposed by Aboitiz et al., or as a new dorsal pallium derivative in mammals which undergoes a surface expansion concomitant with the expansion of the dorsal tier of the dorsal thalamus.
Reptilian cortex and mammalian neocortex early developmental homologies
Authors: Marín-Padilla Miguel
Published: April 2004

I agree with the view expressed in the target article that the early structural organization of the mammalian neocortex (the primordial neocortical organization) is different from its final one and resembles the more primitive organization of reptilian cortex. During the early development of the neocortex, a distinctly mammalian multilayered pyramidal-cell plate is introduced within a more primitive reptilian-like cortex, establishing simultaneously layer I (marginal zone) above it and layer VII (subplate zone) below it. This multilayered pyramidal-cell plate represents a recent mammalian innovation in the evolution of the cerebral cortex of vertebrates. Hence, the term neocortex is preferable to isocortex.
The origin of the amniote sensory and motor cortices
Authors: Martinez-Garcia Fernando
Published: April 2004

A rigorous cladistic analysis of the dorsal pallium of amniotes indicates that the stem amniote lacked sensorimotor areas. Reptiles apparently acquired a visual cortex by parcellation from the multimodal, hippocampal-like mediodorsal pallium of stem amniotes. The high number of sensory areas of the mammalian isocortex might derive from the specific properties it shows, such as growth-promoting influence on thalamic axons.
Histogenetic divisions, developmental mechanisms, and cortical evolution
Authors: Medina Loreta
Published: April 2004

An alteration in the developmental mechanisms that regulate telencephalic patterning or pallial growth may have led to an enlargement of the dorsal pallium during evolution, and to the origin of isocortex. Developmental mechanisms that may have produced a pallial enlargement, and the parallelism of this event with the enlargement of the dorsal thalamus during evolution are discussed.
The data do not support the hypothesis
Authors: Reiner Anton
Published: April 2004

The position that Aboitiz et al. have taken on the regions of the stem amniote brain from which neocortex arose, and on homologies among telencephalic pallial regions in mammals and sauropsids, is premature. Nonetheless, if their intent is to promote thought, discussion, and experimentation on this important topic, then their paper is valuable.
What about embodiment?
Authors: Spurrett David
Published: April 2004

I present reasons for adding an embodiment criterion to the list defended by Anderson & Lebiere (A&L). I also entertain a likely objection contending that embodiment is merely a type of dynamic behavior and is therefore covered by the target article. In either case, it turns out that neither connectionism nor ACT-R do particularly well when it comes to embodiment.
Poppering the Newell Test
Authors: Taatgen Niels A.
Published: April 2004

The Newell Test as it is proposed by Anderson & Lebiere (A&L) has the disadvantage of being too positivistic, stressing areas a theory should cover, instead of attempting to exclude false predictions. Nevertheless, Newell's list can be used as the basis for a more stringent test with a stress on the falsifiability of the theory.
Cognitive modelling of human temporal reasoning
Authors: ter Meulen Alice G. B.
Published: April 2004

Modelling human reasoning characterizes the fundamental human cognitive capacity to describe our past experience and use it to form expectations as well as plan and direct our future actions. Natural language semantics analyzes dynamic forms of reasoning in which the real-time order determines the temporal relations between the described events, when reported with telic simple past-tense clauses. It provides models of human reasoning that could supplement ACT-R models.
Cognitive architectures need compliancy, not universality
Authors: Young Richard M.
Published: April 2004

The criterion of computational universality for an architecture should be replaced by the notion of compliancy, where a model built within an architecture is compliant to the extent that the model allows the architecture to determine the processing. The test should be that the architecture does easily – that is, enables a compliant model to do – what people do easily.
Treating irritable bowel syndrome: overview, perspective and future therapies
Authors: Camilleri Michael
Published: April 2004

This article summarizes the ongoing challenges in irritable bowel syndrome and the exciting opportunities for development of novel therapies for this common, enigmatic condition. The challenges include insufficient understanding of mechanisms, lack of specificity of symptoms, differentiation from other conditions, and lack of availability of noninvasive tests to identify dysfunctions. However, significant opportunities are reflected by the advances in clinical trial design and, particularly, clinically relevant end points for such trials, and the increasing understanding of basic neuroenteric science. The latter has delivered two new medications to the practice (alosetron and tegaserod), and other candidate therapies (other serotonergic, tachykininergic, opioid, cannabinoid modulators) are being carefully appraised as potential drugs for the future.

British Journal of Pharmacology (2004) 141, 1237–1248. doi:10.1038/sj.bjp.0705741
Modulation of visceral pain and inflammation by protease‐activated receptors
Authors: Vergnolle Nathalie
Published: April 2004

The gastrointestinal (GI) tract is exposed to a large array of proteases, under both physiological and pathophysiological conditions. The discovery of G protein‐coupled receptors activated by proteases, the protease‐activated receptors (PARs), has highlighted new signaling functions for proteases in the GI tract, particularly in the domains of inflammation and pain mechanisms. Activation of PARs by selective peptidic agonists in the intestine or the pancreas leads to inflammatory events and changes in visceral nociception, suggesting that PARs could be involved in the modulation of visceral pain and inflammation. PARs are present in most of the cells that are potentially actors in the generation of irritable bowel syndrome (IBS) symptoms. Activation of PARs interferes with several pathophysiological factors that are involved in the generation of IBS symptoms, such as altered motility patterns, inflammatory mediator release, altered epithelial functions (immune, permeability and secretory) and altered visceral nociceptive functions. Although definitive studies using genetically modified animals, and, when available, pharmacological tools, in different IBS and inflammatory models have not yet confirmed a role for PARs in those pathologies, PARs appear as promising targets for therapeutic intervention in visceral pain and inflammation processes.

British Journal of Pharmacology (2004) 141, 1264–1274. doi:10.1038/sj.bjp.0705750
Escherichia coli
nucleoside diphosphate kinase does not act as a uracil-processing DNA repair nuclease
Authors: Bennett Samuel E. , Chen Cheng-Yao , Mosbaugh Dale W.
Published: April 2004

Escherichia coli
nucleoside diphosphate kinase (Ndk) catalyzes ATP-dependent synthesis of ribo- and deoxyribonucleoside triphosphates from the cognate diphosphate precursor. Recently, the Ndk polypeptide was reported to be a multifunctional base excision repair nuclease that processed uracil residues in DNA by acting sequentially as a uracil-DNA glycosylase inhibitor protein (Ugi)-sensitive uracil-DNA glycosylase, an apurinic/apyrimidiniclyase, and a 3′-phosphodiesterase [Postel, E. H. & Abramczyk, B. M. (2003)
Proc. Natl. Acad. Sci. USA
100, 13247–13252]. Here we demonstrate that the
E. coli
Ndk polypeptide lacked detectable uracil-DNA glycosylase activity and, hence, was incapable of acting as a uracil-processing DNA repair nuclease. This finding was based on the following observations: (
i
) uracil-DNA glycosylase activity did not copurify with Ndk activity; (
ii
) Ndk purified from
E. coli ung
-
cells showed no detectable uracil-DNA glycosylase activity; and (
iii
) Ndk failed to bind to a Ugi-Sepharose affinity column that tightly bound
E. coli
uracil-DNA glycosylase (Ung). Collectively, these observations demonstrate that the
E. coli
Ndk polypeptide does not possess inherent uracil-DNA glycosylase activity.
Lineage specificity of gene expression patterns
Authors: Kluger Yuval , Tuck David P. , Chang Joseph T. , Nakayama Yasuhiro , Poddar Ranjana , Kohya Naohiko , Lian Zheng , Nasr Abdelhakim Ben , Halaban H. Ruth , Krause Diane S. , Zhang Xueqing , Newburger Peter E. , Weissman Sherman M.
Published: April 2004

The hematopoietic system offers many advantages as a model for understanding general aspects of lineage choice and specification. Using oligonucleotide microarrays, we compared gene expression patterns of multiple purified hematopoietic cell populations, including neutrophils, monocytes, macrophages, resting, centrocytic, and centroblastic B lymphocytes, dendritic cells, and hematopoietic stem cells. Some of these cells were studied under both resting and stimulated conditions. We studied the collective behavior of subsets of genes derived from the Biocarta database of functional pathways, hand-tuned groupings of genes into broad functional categories based on the Gene Ontology database, and the metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes database. Principal component analysis revealed strikingly pervasive differences in relative levels of gene expression among cell lineages that involve most of the subsets examined. These results indicate that many processes in these cells behave differently in different lineages. Much of the variation among lineages was captured by the first few principal components. Principal components biplots were found to provide a convenient visual display of the contributions of the various genes within the subsets in lineage discrimination. Moreover, by applying tree-constructing methodologies borrowed from phylogenetics to the expression data from differentiated cells and stem cells, we reconstructed a tree of relationships that resembled the established hematopoietic program of lineage development. Thus, the mRNA expression data implicitly contained information about developmental relationships among cell types.
Sgt1p and Skp1p Modulate the Assembly and Turnover of CBF3 Complexes Required for Proper Kinetochore Function
Authors: Rodrigo-Brenni Monica C. , Thomas Scott , Bouck David C. , Kaplan Kenneth B.
Published: April 2004

Kinetochores are composed of a large number of protein complexes that must be properly assembled on DNA to attach chromosomes to the mitotic spindle and to coordinate their segregation with the advance of the cell cycle. CBF3 is an inner kinetochore complex in the budding yeast Saccharomyces cerevisiae that nucleates the recruitment of all other kinetochore proteins to centromeric DNA. Skp1p and Sgt1p act through the core CBF3 subunit, Ctf13p, and are required for CBF3 to associate with centromeric DNA. To investigate the contribution of Skp1p and Sgt1p to CBF3 function, we have used a combination of in vitro binding assays and a unique protocol for synchronizing the assembly of kinetochores in cells. We have found that the interaction between Skp1p and Sgt1p is critical for the assembly of CBF3 complexes. CBF3 assembly is not restricted during the cell cycle and occurs in discrete steps; Skp1p and Sgt1p contribute to a final, rate-limiting step in assembly, the binding of the core CBF3 subunit Ctf13p to Ndc10p. The assembly of CBF3 is opposed by its turnover and disruption of this balance compromises kinetochore function without affecting kinetochore formation on centromeric DNA.
The NMR structure of a stable and compact all‐β‐sheet variant of intestinal fatty acid‐binding protein
Authors: Ogbay Benhur , Dekoster Gregory T. , Cistola David P.
Published: April 2004

Intestinal fatty acid‐binding protein (I‐FABP) has a clam‐shaped structure that may serve as a scaffold for the design of artificial enzymes and drug carriers. In an attempt to optimize the scaffold for increased access to the interior‐binding cavity, several helix‐less variants of I‐FABP have been engineered. The solution‐state NMR structure of the first generation helix‐less variant, known as Δ17‐SG, revealed a larger‐than‐expected and structurally ill‐defined loop flanking the deletion site. We hypothesized that the presence of this loop, on balance, was energetically unfavorable for the stability of the protein. The structure exhibited no favorable pairwise or nonpolar interactions in the loop that could offset the loss of configurational entropy associated with the folding of this region of the protein. As an attempt to generate a more stable protein, we engineered a second‐generation helix‐less variant of I‐FABP (Δ27‐GG) by deleting 27 contiguous residues of the wild‐type protein and replacing them with a G‐G linker. The deletion site of this variant (D9 through N35) includes the 10 residues spanning the unstructured loop of Δ17‐SG. Chemical denaturation experiments using steady‐state fluorescence spectroscopy showed that the second‐generation helix‐less variant is energetically more stable than Δ17‐SG. The three‐dimensional structure of apo‐Δ27‐GG was solved using triple‐resonance NMR spectroscopy along with the structure calculation and refinement protocols contained in the program package ARIA/CNS. In spite of the deletion of 27 residues, the structure assumes a compact all‐β‐sheet fold with no unstructured loops and open access to the interior cavity.
Deletion of the TWIST gene in a large five‐generation family
Authors: De Heer IM , Hoogeboom AJM , Eussen HJ , Vaandrager JM , De Klein A
Published: April 2004

In this article, we describe a large five‐generation family with characteristics of the Saethre–Chotzen syndrome as well as of the blepharophimosis ptosis epicanthus inversus syndrome. Segregating with their phenotype is a deletion of the chromosome 7p21 TWIST gene locus. The TWIST gene indeed is involved in Saethre–Chotzen syndrome, a craniosynostosis syndrome further characterized by specific facial and limb abnormalities. However, only two members of our family exhibited craniosynostosis. This report demonstrates that the genetics of craniofacial anomalies are less straightforward than they sometimes appear to be. Not only craniosynostosis, but also subtle facial deformities could be indicative of an abnormality of the TWIST gene. In conclusion, the clinical spectrum of genetic abnormalities of the TWIST gene is highly variable. We therefore recommend that genetic analysis of the TWIST gene locus, including fluorescence in situ hybridization, should be considered in familial cases of facial and eyelid abnormalities without the presence of craniosynostosis.
Secondary structure of a dynamic type I’β‐hairpin peptide
Authors: Stotz C.E. , Borchardt R.T. , Middaugh C.R. , Siahaan T.J. , Vander Velde D. , Topp E.M.
Published: April 2004

Abstract:  A spontaneously folding β‐hairpin peptide (Lys‐Lys‐Tyr‐Thr‐Val‐Ser‐Ile‐Asn‐Gly‐Lys‐Lys‐Ile‐Thr‐Val‐Ser‐Ile) and related cyclic (cyclo‐Gly‐Lys‐Tyr‐Ile‐Asn‐Gly‐Lys‐Ile‐Ile‐Asn) and linear (Ser‐Ile‐Asn‐Gly‐Lys) controls were studied to determine the effects of various factors on secondary structure. Secondary structure was evaluated using circular dichroism (CD) and 1D and 2D 1H nuclear magnetic resonance (NMR). The effects of chemical modifications in the peptide and various solution conditions were investigated to determine their impact on peptide structure. The β‐hairpin peptide displayed a CD minimum at 216 nm and a TOCSY i + 1 − i + 2 and i + 2 −i + 3 interaction, confirming the expected structure. Using NMR α‐proton (H) chemical shifts, the extents of folding of the β‐hairpin and linear control were estimated to be 51 and 25% of the cyclic control (pH 4, 37 °C), which was taken to be maximally folded. Substitution of iso‐aspartic acid for Asn reduced the secondary structure dramatically; substitution of aspartic acid for Asn also disrupted the structure. This result suggests that deamidation in unconstrained β‐turns may have adverse effects on secondary structure. N‐terminal acetylation and extreme pH conditions also reduced structure, while the addition of methanol increased structure.
Ability, Education, and Income Inequality
Authors: Cardak Buly A.
Published: April 2004

A model of education where the distribution of abilities is the source of heterogeneity is investigated. Ability is a key determinant of human capital accumulated when young, which in turn determines income and its distribution. The assumption of heterogeneous abilities leads to steady‐state income distributions that exhibit income inequality. Of particular interest is the result that symmetric distributions of ability generate positively skewed income distributions. Models of private and public education are analyzed and compared. It is found that private education results in higher incomes and less income inequality than observed in the public education model.
Mother‐Infant Interaction and Maternal Substance Use/Abuse: An Integrative Review of Research Literature in the 1990s
Authors: Johnson Merrilyn O.
Published: April 2004

Purpose

(1) Mother‐infant interaction is crucial for optimal infant development and parenting. In the environment of prenatal substance use/abuse there is potential for both mother and child to present negative interactive behaviors. Recent increased incidence of substance use/abuse by pregnant women in the United States has provoked concern for the infant's outcome in these circumstances. Recent literature does not indicate uniformly dismal outlook for infants born exposed to drugs. In this paper, published research from the 1990s that specifically addressed the relationship between prenatal substance use/abuse and the mother‐infant interaction was examined utilizing the Barnard model of parent‐infant interaction as a guide. Twenty‐three articles matched search criteria and were included in the review.

Conclusions

(2) The majority of studies (14/23) showed that maternal substance abuse was associated with a recognizably detrimental impact on mother‐child interaction. Six studies did not confirm an adverse effect. Negative impact on the interaction was related to the degree of maternal substance abuse in three studies and to its continuation postnatally in two. Postnatal environment correlated strongly with the quality of mother‐child interaction in the substance‐exposed dyads.

Implications

(3) Clinical and research implications are described.
Development of a standardized method for comparing fluoride ingested from toothpaste by 1.5‐3.5‐year‐old children in seven European countries. Part 1: Field work
Authors: Cochran Judith A. , Ketley Clare E. , Duckworth Ralph M. , Van Loveren Cor , Holbrook W Peter , Seppä Liisa , Sanches Leonor , Polychronopoulou Argy , O'Mullane Denis M.
Published: April 2004

Abstract ‐ Objectives:To develop a standardized method for measuring the variables affecting fluoride ingestion from toothpaste in young children between the ages of 1.5 and 3.5 years, and to use the method at seven European sites.Methods:Random samples of children were invited to take part in the study. Parents who gave consent were visited at home. The children brushed their teeth using the toothpaste brand and toothbrush type currently in use. Variables measured were: type of toothpaste used, fluoride concentration of toothpaste used, weight of toothpaste used, frequency of brushing and body weight of the child.Results:It was not possible to follow the agreed protocol in all seven countries and in three countries appropriate alternative methods were employed. There was considerable variation between countries in the variables investigated. Use of children's toothpaste ranged from 69% in Ireland to 98% in Portugal. In the Netherlands up to 60% of the children were using toothpaste containing <400 ppm F and in Finland up to 27% of children were using toothpaste containing >1200 ppm F. Over half of the children used <0.25 g of toothpaste per brushing and the majority of children brushed once or twice per day.Conclusion:Although adherence to the agreed protocol was not possible at all study sites there was a clear picture of considerable variation in the oral hygiene practices of young children throughout Europe.
Fluoride ingestion from toothpaste: conclusions of European Union‐funded multicentre project
Authors: O'Mullane Denis M. , Ketley Clare E. , Cochran Judith A. , Whelton Helen P. , Holbrook W Peter , Van Loveren Cor , Fernandes Barros , Seppä Liisa , Athanassouli Thessaly
Published: April 2004

Abstract ‐  An important challenge encountered in this multicentred project was the need to take account of the different cultural and legal differences between the seven sites when agreeing the protocol. Examples such as access to registers of births and subject consent dictated that there were some differences in the methods used in the different sites. The data presented showed that it was possible to train and calibrate a number of examiners in a standardized photographic method for recording enamel fluorosis. This method has a number of important advantages for the objective monitoring of enamel fluorosis over time. There were considerable differences between the seven sites in the formulations of the toothpaste used and in the pattern of their use. The results indicate that it is possible to agree and adopt a standardized method for measuring fluoride ingestion from toothpaste. The aesthetic impact of enamel fluorosis seemed low in the populations included in this project, but further work is required on this issue.
Long‐Term Population Decline in Europe: The Relative Importance of Tempo Effects and Generational Length
Authors: Goldstein Joshua , Lutz Wolfgang , Scherbov Sergei
Published: April 2004

It has recently been suggested that an end to further increases in the mean age of child‐bearing in Europe (ending the negative tempo effect on fertility) would have a substantial effect on population dynamics in terms of slowing population aging and decline and weakening the negative momentum affecting population size over the coming decades. On the other hand, stable population theory suggests that under sub‐replacement fertility conditions, a longer mean length of generations implies slower shrinking, and thus a relatively larger population in the very long run. This note compares the relative importance of the two effects analytically and with data for the 15‐country European Union. It also considers whether an increase in the mean age of childbearing will decrease the quantum of fertility. This question is highly relevant in the context of the effects of possible policies aiming to influence the tempo of fertility rather than the quantum directly. The results show that for the coming 200 years the effect of tempo changes clearly dominates, with the effect of a shorter mean length of generation only becoming visible thereafter. Even small tempo‐quantum interactions can overwhelm the generation‐length effect.
Short Reviews
Authors: Bongaarts John , Casterline John B. , Greenhalgh Susan , McNicoll Geoffrey , Todaro Michael P.
Published: April 2004

Books reviewed in this article:

Leonore Loeb Abler and Uwe P. Gielen(EDS.), Migration: Immigration and Emigration in International Perspective

Samuel Agyei‐Mensah and John B. Casterline(EDS.), Reproduction and Social Context in Sub‐Saharan Africa: A Collection of Micro‐Demographic Studies

Francesco C. Billari And Alexia Prskawetz(EDS.), Agent‐Based Computational Demography: Using Simulation to Improve Our Understanding of Demographic Behaviour

Siew‐Ean Khoo And Peter McDonald(EDS.), The Transformation of Australia's Population: 1970‐2030

James P. Lynch and Rita J. Simon, Immigration the World Over: Statutes, Policies, and Practices

C. Ford Runge, Benjamin Senauer, Philip G. Pardey, And Mark W. Rosegrant, Ending Hunger in Our Lifetime: Food Security and Globalization

Sheldon J. Segal, Under the Banyan Tree: A Population Scientist's Odyssey

Lynn M. Thomas, Politics of the Womb: Women, Reproduction, and the State in Kenya

United Nations Economic Commission For Europe, Dynamics of Fertility and Partnership in Europe: Insights and Lessons from Comparative Research
Coentrepreneurial Couples: A Literature Review on Boundaries and Transitions Among Copreneurs
Authors: Marshack Kaihy J.
Published: April 2004

Couple-owned businesses are a rapidly growing segment of family businesses. They are also fascinating examples of the interaction and interdependence of personal relationship and business partnership, or love and work. Inasmuch as many home-based family businesses are the products of husband-wife team efforts, there is an opportunity to examine the recursive interaction between love and work that coentrepreneurial couples represent. This article reviews the research literature on coentrepreneurial couples, or copreneurs, to illustrate how these couples manage the boundaries and transitions of personal relationship and business partnership. The literature is sparse that focuses specifically on the copreneurial relationship. However, valuable insights can be drawn from the research of dual-career couples, executives, and family businesses in general. And these insights can be turned into questions and hypotheses for future research on copreneurs.