bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of smectites and Al-substituted goethites in the catalytic condensation of arginine and glucose
Authors: Gonzalez Javier M. , Laird David A. 
Published: August 2004

AbstractThe polyphenol theory of humic-substance formation has been studied extensively; however, an alternative theory, that humic substances are formed through the condensation of amino acids and reducing sugars (Maillard reaction), has not been explored to the same extent. The general objectives of this study were to determine whether smectites and goethites catalyze the abiotic polymerization of arginine and glucose to form humic-like compounds. The effects of smectite type, saturating cation, and the degree of Al substitution in goethites on the polymerization reaction were also studied. Four cation-saturated smectites and four Al-substituted goethites were incubated abiotically with solutions containing a mixture of arginine + glucose for 21 days at 37°C. After the incubations, total C recovered ranged from 80.6 to 123.8% and from 100.5 to 105.1% for the smectite and goethite systems, respectively. At the end of the incubations, 21.4–50.3% of the added C and 16.5–90% of the added N were sorbed on the various smectites, and 6.2–9.0% of the added C and 2.3–4.6% of added N was sorbed on the goethites in a form that could not be desorbed by washing with 100 mM CaCl2. X-ray diffraction analysis indicated that some of the sorbed C was intercalated in the smectites and FTIR analysis provided evidence of new absorption bands at 1650 and 1668 cm−1, which are consistent with Maillard reaction products. Thus, it is concluded that smectites catalyze the condensation of arginine and glucose to form humic-like products. Goethites, however, have little or no ability to catalyze this reaction.
Mixed-layer kaolinite-smectite minerals in a red-black soil sequence from basalt in Sardinia (Italy)
Authors: Vingiani Simona , Righi Dominique , Petit Sabine , Terribile Fabio 
Published: August 2004

AbstractClay minerals from soils of a red-black soil complex developed from basaltic parent material in Sardinia are formed along a short toposequence (200 m). At the foot of the sequence, a clay-rich, black Vertisol forms, whereas at the summit, the soil is a dark reddish-brown Inceptisol. X-ray diffraction, infrared spectroscopy (FTIR), cation exchange capacity (CEC) and permanent and variable charges analyses were used, and the data show that clay minerals varied according to soil horizon and topographic position of the soil. Clay minerals in the Inceptisol are dominated by kaolinite and mixed-layer kaolinitesmectite (K-S, K:S >0.5), whereas the Vertisol contains smectites and K-S with K:S proportions <0.5. In the Vertisol, the proportion of kaolinitic layers in the K-S increases from the C horizon (K:S ∼0.35–0.40) to the Ap horizon (K:S ∼0.40–0.45). This soil clay-mineral distribution, in relation to topography, is similar to that reported for other (kaolinitic) red-black (smectitic) soil associations in subtropical and tropical areas. The sequence forms by downward drainage on summits and slopes, and buildup of ions in ‘lows’ produces smectites. Fourier transform infrared spectra indicate that two types of smectite are formed in the C horizon of the Vertisol; one is more ferric (Fe-beidellite, nontronite), the other more aluminous. Mineralogical evolution in the soil profile (from C to Ap horizon) shows a decreasing proportion of ferric smectite layers (compared to the more aluminous smectite layers). This would indicate that ferric smectite layers are preferentially transformed (or dissolved) to give kaolinite layers, with Fe precipitating as oxides and/or oxy-hydroxides or retained partly in kaolinite layers. Because the surface properties of clay minerals are related to mineralogy, the CEC (33–41 cmol kg−1) in the brown Inceptisol is ∼50% pH-dependent charge while in the Vertisol up to ∼75% of the CEC (48–61 cmol kg−1) comes from accessible permanent charges.
Desiccants
Authors: Cohen Alan P. 
Published: July 2004

AbstractDesiccants are classified by four drying mechanisms: chemical reaction, physical absorption with constant relative humidity, physical absorption with variable relative humidity, and physical adsorption. Solid desiccant materials including activated alumina, silica gel, molecular sieves, and lithium chloride are commonly used in both static and dynamic drying. Other solids such as barium oxide, calcium chloride, calcium oxide, calcium sulfate, clays, metal halides, perchlorates, phosphorus pentoxide, sodium and potassium hydroxides, are used mainly in static drying.Desiccants must be chemically compatible with the material being dried, and, if in doubt, the compatibility should be tested prior to use. Ideally, the desiccant and the material should not react to avoid producing harmful or undesirable by‐products. The water capacity of some static desiccants and the efficiency (or effectiveness) of various desiccants in drying air and laboratory solvents vary widely. The dynamics of closed‐system drying involves the exponential decay of the water content over time.Desiccants used in dynamic applications include both liquids and solids. Solid adsorbents are often used in drying systems with multiple beds, and sometimes in rotating wheels. The largest users of solid desiccants are the hydrocarbon processing, insulating glass drying, and packaging industries.
Hydrogen Induced Polarization–Nuclear‐Spin Hyperpolarization in Catalytic Hydrogenations without the Enrichment of Para‐ or Orthohydrogen
Authors: Jonischkeit Thorsten , Woelk Klaus 
Published: August 2004

AbstractDuring the last 40 years, Prof. Dr. Joachim Bargon, to whom several articles in this issue are dedicated, has contributed more than 90 scientific publications to the understanding of NMR hyperpolarization phenomena such as chemically induced dynamic nuclear polarization (CIDNP) or parahydrogen induced polarization (PHIP). Both techniques are extremely useful for elucidating the mechanisms and kinetics of chemical reactions involving radicals or catalytic hydrogenations, respectively. To honor Joachim Bargon's scientific achievements, we dedicate to him an additional, newly discovered and somewhat unexpected twist to the PHIP methodology. Accordingly, NMR spectra exhibit the unique, enhanced absorption and emission patterns of PHIP not only if the hydrogen for the catalytic reactions is enriched in one of its nuclear spin states (parahydrogen or orthohydrogen) but also if it is at its thermodynamic equilibrium. Thermally equilibrated gaseous hydrogen is obtained from commercially available hydrogen gas bombs or from electrolytic hydrogen generators. The new finding is explained with the quantum mechanical properties of the small, highly symmetric hydrogen molecule.
Conformationally Restricted Arene Intermediates in the Intermolecular Heck Arylation of Vinylarenes
Authors: Hii King Kuok (Mimi) , Claridge Timothy D. W. , Giernoth Ralf , Brown John M. 
Published: August 2004

AbstractThe NMR observation of σ‐benzylpalladium intermediates at low temperature, formed by reaction of arylpalladium diphosphine cations with simple vinylarenes, indicates restricted rotation in the adjacent aryl ring. The stability of the intermediate is greater in the dppp than in the dppf series. By a combination of NMR techniques, it was possible to characterise the intermediate, and to consider permissible structures.
Efficient Synthesis of Tris(acetonitrile)‐(η5‐cyclopentadienyl)‐ ruthenium(II) Hexafluorophosphate via Ruthenocene
Authors: Kündig E. Peter , Monnier Florian R. 
Published: August 2004

Abstract[Ru(η5‐C5H5)(CH3CN)3][PF6] (1), a versatile precursor to catalysts containing the CpRu+ complex fragment, can be obtained in high yield via Cp/naphthalene exchange in ruthenocene. This new route via the complex [RuCp(naphthalene)][PF6] (4) avoids both highly toxic thallium reagents and the need for a photoreactor.
Demographic trends and biological status of historic populations from Central Poland: The Ostrów Lednicki microregion
Authors: Budnik Alicja , Liczbińska Grażyna , Gumna Izabela 
Published: July 2004

AbstractThe microregion of Ostrów Lednicki in the province of Wielkopolska was the center of the formation of the Polish State in Early Middle Ages. The analysis of skeletal remains and parish records from the region documented the biological status of inhabitants and its changes over a millennium. The study material comprised 424 human skeletons from an Early Medieval burial ground on Lake Lednica, records of 2,704 deaths from the registers of the Roman Catholic parish of Dziekanowice, made between 1818–1903, data on the deaths of 929,192 inhabitants of rural areas all over the province Wielkopolska obtained from Prussian statistical materials for the years 1865–1900, and comparative data from the literature. Assuming both a stationary population model and a stable population model with nonzero natural increase, parameters of life tables and measures of opportunity for natural selection (Crow's index Im, potential gross reproductive rate Rpot, and the biological state index Ibs) were calculated for the Early Middle Ages and for the two periods of the 19th century which were characterized by different laws of land ownership and thus different rural economies. In the first period, peasants were tenants, whereas in the second, they were given freehold of the land they cultivated. Causes of death were also analyzed. A distinct increase in longevity from the early Middle Ages to the end of the 19th and the beginning of the 20th century was found. This was related to a higher level of demographic development in the parish of Dziekanowice during the 19th century, which was achieved earlier than in other areas of Poland. This was confirmed by genetic measures: coefficients of exogamy and coefficients of kinship. The reasons were related to the historical prominence of this region and to its proximity to the first two capitals of the Polish state, Gniezno and Poznań. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
New method for surname studies of ancient patrilineal population structures, and possible application to improvement of Y‐chromosome sampling
Authors: Manni Franz , Toupance Bruno , Sabbagh Audrey , Heyer Evelyne 
Published: July 2004

AbstractSeveral studies showed that surnames are good markers to infer patrilineal genetic structures of populations, both on regional and microregional scales. As a case study, the spatial patterns of the 9,929 most common surnames of the Netherlands were analyzed by a clustering method called self‐organizing maps (SOMs). The resulting clusters grouped surnames with a similar geographic distribution and origin. The analysis was shown to be in agreement with already known features of Dutch surnames, such as 1) the geographic distribution of some well‐known locative suffixes, 2) historical census data, 3) the distribution of foreign surnames, and 4) polyphyletic surnames. Thus, these results validate the SOM clustering of surnames, and allow for the generalization of the technique. This method can be applied as a new strategy for a better Y‐chromosome sampling design in retrospective population genetics studies, since the idenfication of surnames with a defined geographic origin enables the selection of the living descendants of those families settled, centuries ago, in a given area. In other words, it becomes possible to virtually sample the population as it was when surnames started to be in use. We show that, in a given location, the descendants of those individuals who inhabited the area at the time of origin of surnames can be as low as ∼20%. This finding suggests 1) the major role played by recent migrations that are likely to have distorted or even defaced ancient genetic patterns, and 2) that standard‐designed samplings can hardly portray a reliable picture of the ancient Y‐chromosome variability of European populations. Am J Phys Anthropol 126:214–228, 2005. © 2004 Wiley‐Liss, Inc.
Analysis of dental attrition and mortality in the Medieval village of Tirup, Denmark
Authors: Boldsen Jesper L. 
Published: July 2004

AbstractNew directions and new questions raised in the study of health in the past justify this reanalysis of the pattern of dental attrition in the Medieval Danish population of Tirup. Dental attrition was scored on all permanent molars from the Tirup skeletal sample. Scores were analyzed by means of logistic regression of the probability of having entered a given stage of wear for a given tooth in a way that is very similar to transition analysis. The primary determinant of dental attrition was age at death. In addition to age, the effects of sex, side, and dating were analyzed. In order to assess the homogeneity of the process of wearing teeth down, a third‐order polynomial in age‐at‐death was also fitted to the transition probabilities. It was found that age is the single most important determinant of dental attrition, and that sex or side did not differentiate the rate of attrition. In several transitions, there was evidence of heterogeneity, indicating both random and systematic interpersonal differences in the rate of attrition and an association between the rate of attrition and age‐at‐death. It was found that attrition proceeded more quickly after AD 1300 than prior to that date. It is suggested that this was due to a possible general deterioration of living conditions in Northern Europe and an increased reliance on grain for food during the first half of the 14th century. The temporal effect on attrition rate accounts for some but not all the observed heterogeneity wear. Am J Phys Anthropol 126:169–176, 2005. © 2004 Wiley‐Liss, Inc.
Humeral cross‐sectional morphology from 18th century Quebec prisoners of war: Limits to activity reconstruction
Authors: Weiss Elizabeth 
Published: July 2004

AbstractThis study uses measures of cross‐sectional robusticity and asymmetry (based on humeral areal and inertial cross‐sectional components) to test a prediction from bone remodeling theory that a physically active 18th century Quebec prisoner of war sample (N = 25) should have more robust and asymmetrical humeri than a nonphysically active 20th century New Mexico suburbanite sample (N = 27). Narrative accounts document that prisoners of war engaged in labor‐intensive activities, and these activities were confirmed by observations of osteoarthritis and other pathologies. The suburbanite sample, for the most part, did not engage in such activities. The prisoners had higher levels of pathology than the suburbanites (e.g., 80% vs. 22% osteoarthritis; F = 17.95, P < 0.01). For robusticity, the populations did not differ significantly in total area, cortical area, moment areas of inertia about the mediolateral plane, or polar moment area of inertia. The Quebec prison sample did have significantly higher values for moment areas of inertia about the anteroposterior plane. For asymmetry, the populations did not differ in any values (total area, cortical area, moment areas of inertia about the mediolateral plane, moment areas of inertia about the anteroposterior plane, or polar moment of inertia). Thus, examinations of cross‐sectional robusticity and asymmetry failed to conclusively confirm the hypothesis that intensive labor leads to changes in humeral morphology. Possible explanations for the lack of differences are discussed, such as poor diet impeding bone remodeling. Nevertheless, the one significant finding suggests that cross‐sectional shape is more useful in reconstructing activity patterns than amount of bone in a cross section. Results from this study join those from other recent investigations to suggest that additional controls are required before cross‐sectional differences may be confidently attributed to activity patterns. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
Interactions of tamoxifen, N‐desmethyltamoxifen and 4‐hydroxytamoxifen with P‐glycoprotein and CYP3A
Authors: Bekaii‐Saab Tanios S. , Perloff Michael D. , Weemhoff James L. , Greenblatt David J. , von Moltke Lisa L. 
Published: July 2004

AbstractThe effects of tamoxifen, N‐desmethyltamoxifen and 4‐hydroxytamoxifen on transport attributable to P‐glycoprotein were studied using Caco‐2 cell monolayers in a transwell system, with rhodamine‐123 as an index substrate for inhibition studies. The three compounds did not demonstrate differential flux between basal‐apical and apical‐basal directions in Caco‐2 monolayers. The mean IC50 values for inhibition of rhodamine‐123 transport were: 29 µM for tamoxifen; 26 µM for N‐desmethyltamoxifen; and 7.4 µM for 4‐hydroxytamoxifen. The three compounds were also evaluated as potential inhibitors of human CYP3A based on an in vitro model using triazolam hydroxylation by human liver microsomes as an index reaction. Mean (±SE) IC50 values versus formation of α‐hydroxy‐triazolam and 4‐hydroxy‐triazolam in human liver microsomes were, respectively: 23.5 (±3.9) and 18.4 (±5.3) µM for tamoxifen; 10.2 (±1.7) and 9.2 (±1.5) µM for N‐desmethyltamoxifen; and 2.6 (±0.5) and 2.7 (±0.3) µM for 4‐hydroxytamoxifen. Thus, tamoxifen, N‐desmethyltamoxifen and 4‐hydroxytamoxifen, do not appear to be substrates for transport by P‐glycoprotein. However, tamoxifen has the potential to inhibit transport mediated by P‐glycoprotein as well as CYP3A‐mediated metabolism. Inhibitory effects of the principal metabolites, N‐desmethyltamoxifen and 4‐hydroxytamoxifen, may exceed those of the parent drug. Tamoxifen, and possibly its metabolites, may have the potential to cause drug interactions by inhibiting both drug transport and metabolism. This possibility requires further evaluation in clinical studies. Copyright © 2004 John Wiley & Sons, Ltd.
Dynamics of water molecules buried in cavities of apolipoprotein E studied by molecular dynamics simulations and continuum electrostatic calculations
Authors: Prévost Martine 
Published: July 2004

AbstractMolecular dynamics (MD) simulations of several nanoseconds each were used to monitor the dynamic behavior of the five crystal water molecules buried in the interior of the N‐terminal domain of apolipoprotein E. These crystal water molecules are fairly well conserved in several apolipoprotein E structures, suggesting that they are not an artifact of the crystal and that they may have a structural and/or functional role for the protein. All five buried crystal water molecules leave the protein interior in the course of the longest simulations and exchange with water molecules from the bulk. The free energies of binding evaluated from the electrostatic binding free energy computed using a continuum model and estimates of the binding entropy changes represent shallow minima. The corresponding calculated residence times of the buried water molecules range from tens of picoseconds to hundreds of nanoseconds, which denote rather short times as for buried water molecules. Several water exchanges monitored in the simulations show that water molecules along the exit/entrance pathway use a relay of H bonds primarily formed with charged residues which helps either the exit or the entrance from or into the buried site. The exit/entrance of water molecules from/into the sites is permitted essentially by local motions of, at most, two side chains, indicating that, in these cases, complex correlated atomic motions are not needed to open the buried site toward the surface of the protein. This provides a possible explanation for the short residence times. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
A novel convenient procedure for extractive work‐up of whole‐cell biotransformations using de‐emulsifying hydrolases
Authors: Jörg Gerhard , Leppchen Kathrin , Daussmann Thomas , Bertau Martin 
Published: July 2004

AbstractExtractive work‐up of whole‐cell biotransformations generally suffers from the formation of stable gels and slimes upon addition of the organic solvent to the cell suspension and the cell‐free solution, respectively. This problem has been overcome by enzymatic lysis of emulsifying agents present in the medium through addition of hydrolases. Of these agents, proteases have exhibited the most powerful de‐emulsifying activity. Enzyme treatment of cell‐free culture media of Saccharomyces cerevisiae with pronase E drastically reduced phase separation time (tp) from 1 week to 30 min without significantly affecting product integrity. Yeast cell suspensions were de‐emulsified best with protease N‐01, where phase separation was complete after 1 h. As was exemplified with cell‐free culture media of Lactobacillus kefir, wherein addition of pronase E or protease N‐01 reduced tp from 1 week to 2 h each, this practical, ready‐to‐use method is appropriate for both fungal and bacterial biocatalysts. © 2004 Wiley Periodicals, Inc.
Multienzyme mevalonate pathway bioreactor
Authors: Sutherlin Autumn , Rodwell Victor W. 
Published: July 2004

AbstractThe five‐carbon metabolic intermediate isopentenyl diphosphate constitutes the basic building block for the biosynthesis of all isoprenoids in all forms of life. Two distinct pathways lead from amphibolic intermediates to isopentenyl diphosphate. The Gram‐positive cocci and certain other pathogenic bacteria employ exclusively the mevalonate pathway, a set of six enzyme‐catalyzed reactions that convert 3 mol of acetyl‐CoA to 1 mol each of carbon dioxide and isopentenyl diphosphate. The survival of the Gram‐positive cocci requires a fully functional set of mevalonate pathway enzymes. These enzymes therefore represent potential targets of inhibitors that might be employed as antibiotics directed against multidrug‐resistant strains of certain bacterial pathogens. A rapid throughput, bioreactor‐based assay to assess the effects of potential inhibitors on several enzymes simultaneously should prove useful for the survey of candidate inhibitors. To approach this goal, and as a proof of concept, we employed enzymes from the Gram‐positive pathogen Enterococcus faecalis. Purified recombinant enzymes that catalyze the first three reactions of the mevalonate pathway were immobilized in two kinds of continuous flow enzyme bioreactors: a classical hollow fiber bioreactor and an immobilized plug flow bioreactor that exploited a novel method of enzyme immobilization. Both bioreactor types employed recombinant acetoacetyl‐CoA thiolase, HMG‐CoA synthase, and HMG‐CoA reductase from E. faecalis to convert acetyl‐CoA to mevalonate, the central intermediate of the mevalonate pathway. Reactor performance was monitored continuously by spectrophotometric measurement of the concentration of NADPH in the reactor effluent. Additional potential applications of an Ni++ affinity support bioreactor include using recombinant enzymes from extremophiles for biosynthetic applications. Finally, linking a Ni++ affinity support bioreactor to an HPLC‐mass spectrometer would provide an experimental and pedagogical tool for study of metabolite flux and pool sizes of intermediates to model regulation in intact cells. © 2004 Wiley Periodicals, Inc.