bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Prevalence of Pituitary Adenomas: A Cross-Sectional Study in the Province of Liège, Belgium
Authors: Daly Adrian F. , Rixhon Martine , Adam Christelle , Dempegioti Anastasia , Tichomirowa Maria A. , Beckers Albert 
Published: September 2006

Abstract
Context: Prevalence data are important for assessing the burden of disease on the health care system; data on pituitary adenoma prevalence are very scarce.
Objective: The objective of the study was to measure the prevalence of clinically relevant pituitary adenomas in a well-defined population.
Design: This was a cross-sectional, intensive, case-finding study performed in three regions of the province of Liège, Belgium, to measure pituitary adenoma prevalence as of September 30, 2005.
Setting: The study was conducted in specialist and general medical practitioner patient populations, referral hospitals, and investigational centers.
Methods: Three demographically and geographically distinct districts of the province of Liège were delineated precisely using postal codes. Medical practitioners in these districts were recruited, and patients with pituitary adenomas under their care were identified. Diagnoses were confirmed after retrieval of clinical, hormonal, radiological, and pathological data; full demographic and therapeutic follow-up data were collected in all cases.
Results: Sixty-eight patients with clinically relevant pituitary adenomas were identified in a population of 71,972 individuals; the mean (± sd) prevalence was 94 ± 19.3 cases per 100,000 population (95% confidence interval, 72.2 to 115.8). The group was 67.6% female and had a mean age at diagnosis of 40.3 yr; 42.6% had macroadenomas and 55.9% underwent surgery. Prolactinomas comprised 66% of the group, with the rest having nonsecreting tumors (14.7%), somatotropinomas (13.2%), or Cushing’s disease (5.9%); 20.6% had hypopituitarism.
Conclusion: The prevalence of pituitary adenomas in the study population (one case in 1064 individuals) was more than 3.5–5 times that previously reported. This increased prevalence may have important implications when prioritizing funding for research and treatment of pituitary adenomas.
Concurrent Use of Metered-Dose and Dry Powder Inhalers by Children with Persistent Asthma Does Not Adversely Affect Spacer/Inhaler Technique
Authors: Chan Debora S , Callahan Charles W , Hatch-Pigott Virginia B , Lawless Annette , Proffitt H Lorraine , Manning Nola E , Schweikert Mary P 
Published: September 2006

Background: Studies conducted in adults have suggested that patients who use a metered-dose inhaler/holding chamber spacer (MDI/S) and dry powder inhaler (DPI) concurrently will have poorer MDI/S technique than that of patients who use MDI/S exclusively. To our knowledge, as of August 31, 2006, no studies have been performed in pediatric patients. Objective: To compare MDI/S technique scores of children using only MDI/S with scores of those using both MDI/S and DPIs. Methods: The MDI/S technique of children aged 6–17 years, with persistent asthma, recruited from a general pediatric practice population for an asthma intervention study project was scored using a standardized checklist. MDI/S scores of children who were being treated with maintenance and rescue medication delivered only by MDI/S were compared with those treated with both MDI/S (rescue) and DPI (maintenance). Scores lower than 70% were considered to be inadequate. Results: A total of 117 patients (73 male, 44 female), aged 9.70 ± 3.1 years (mean ± SD), with persistent asthma, participated in the study. There were 83 children (54 male, 29 female, age 9.4 ± 3.2 y) in the MDI/S only group and 34 (19 male, 15 female, age 10.3 ± 2.9 y) in the MDI/S + DPI group. In the MDI/S + DPI group, Diskus was the DPI used for 32 patients, and Turbuhaler was used by 2 children. Sixteen patients had severe persistent asthma, 80 had moderate persistent asthma, and 21 had mild persistent asthma as classified by National Heart Lung and Blood Institute guidelines. No difference in sex and age demographics existed; however, there was a difference in the distribution of asthma severity between groups (ie, no patients with mild persistent asthma in the MDI/S + DPI group; p ≤ 0.01). Mean score for the MDI/S only group was 86 ± 17% and, for the MDI/S + DPI group, 90.1 ± 12% (p = 0.15). More patients in the MDI/S group had inadequate scores (18%) compared with those in the MDI/S + DPI group (3%; p < 0.05). Conclusions: While DPI and MDI/S techniques are markedly different in several significant ways, concurrent use of these inhalers did not adversely affect MDI/S technique scores of pediatric patients with persistent asthma, compared with those using MDI/S alone. Patients in the MDI/S only group had an inadequate MDI/S score (<70%) more often than did patients in the MDI/S + DPI group.
Consumption of Dietary Supplements Containing Citrus aurantium (Bitter Orange)—2004 California Behavioral Risk Factor Surveillance Survey (BRFSS)
Authors: Klontz Karl C , Timbo Babgaleh B , Street Debra 
Published: September 2006

Background: Following the marketing ban of ephedra-containing supplements in April 2004, many manufacturers substituted the herb Citrus aurantium for ephedra and marketed the products as “ephedra-free” supplements. Extracts of C. aurantium contain synephrine, a sympathomimetic alkaloid. Objective: To determine the prevalence of consumption of dietary supplements containing C. aurantium in California during 2004. Methods: We used the 2004 California Behavioral Risk Factor Surveillance Survey to determine the prevalence of consumption of dietary supplements containing C. aurantium in California during 2004. Results: Two percent (n = 70) of the 4140 survey respondents reported taking a dietary supplement containing C. aurantium in the previous year. Reasons stated included energy enhancement, weight loss, and appetite suppression. Compared with nonusers, users were more likely to report being single, aged 18–34 years, and Hispanic; consuming 3 or more alcoholic drinks on days that they imbibed; and having a heavier body mass index. Among the 5 users who reported experiencing an adverse event that they attributed to the supplement, 3 indicated that the severity was mild. Conclusions: Given that supplements containing ephedra were banned in April 2004, the results from this study may serve as a baseline estimate against which future studies of the use of C. aurantium products may be compared.
Effect of Pressure on the Sorption of Yb by Montmorillonite
Authors: Miller Steven E. , Ross Heath G. , Gonzalez Richard D. 
Published: September 2006

AbstractX-ray diffraction, infrared, and cation-exchange capacity measurements of the reaction products of montmorillonites with YbCl3.6H2O show that at 1 atm irreversible sorption of Yb3+ increases with increasing temperature in the range 20° to 280°C, whereas at 110 atm it decreases with increasing temperature. Above 100°C, less irreversible sorption occurs at 110 atm than at 1 atm. The decreased sorption at high pressure is attributed to reduced cation hydrolytic fixation and to rapid expulsion of interlayer Yb3+ by interlayer water at higher temperatures, with a concomitant decrease in Yb3+ migration to octahedral sites. At 110 atm, 160° and 200°C treatments cause changes in infrared absorption bands (884 cm-1, 848 cm-1) suggesting that sorbed Yb3+ is charge compensated by the deprotonation of Fe3+- and Mg2+-hydroxyl groups. At 290°C deprotonation is restricted to Fe3+-hydroxyl groups.
Charge Heterogeneity in Smectites
Authors: Talibudeen Oscar , Goulding Keith W. T. 
Published: September 2006

AbstractThe heterogeneity of sites for Ca→K exchange was examined by microcalorimetry in the <0.2-μm fractions of some selected smectites. Six groups of sites, ranging in exothermic exchange enthalpy (-d(ΔHx)/dx) from 5.7 to 10.9 kJ/eq were identified. In Wyoming bentonites, only three groups with enthalpies of 5.7 to 7.5 kJ/eq were distinguished, although in the 0.2-1.0-μm fraction, a 10.7-kJ/eq group was also observed. Redhill and Camp Berteau smectites contained, in addition, groups with enthalpies of 8.7-10.9 kJ/eq, but a New Mexico sample only had groups with the higher values. Thus, the exchange enthalpies of four main groups of sites (reclassified from those observed) appear to be inversely related to the extents of interlayer expansion in the samples by the adsorption of polar molecules. Consequently, a 'true mont-morillonite,’ such as a <0.2-μm Wyoming bentonite, contains only fully expanding layers with -d(ΔHx)/ dx values between 5.7 and 7.5 kJ/eq. As such, it is less heterogeneous and should have a much greater swelling capability than Camp Berteau montmorillonite which has, in addition, groups with exchange enthalpies of 8.7 and 10.3 kJ/eq.
Potassium Fixation by Clay Minerals during Hydrothermal Treatment
Authors: Inoue Atsuyuki 
Published: September 2006

AbstractThe amount of K fixed in K- and Ca-saturated montmorillonite, vermiculite (trioctahedral), rectorite-type and IMII-ordered mica/montmorillonites was measured as a function of time (1–64 days), temperature (25o-300°C), pH (6.0, 9.7, and 10.7), and K-concentration (0.02 and 1.0 M) in solution. The amount of K fixed by the clays generally increased with increasing temperature, pH, and K-concentration and reached saturation in response to each experimental condition in 5 or 6 days. The K-montmorillonite and K-vermiculite fixed considerable amounts of K even at 25°C. Fixed K in montmorillonite increased with an increase of the layer charge which is also influenced significantly by the interlayer cation. In detail, the behavior in K-fixation was specific to each clay.The type of structural transformation with K-fixation was different for each clay. In montmorillonite, especially, the type of transformation was related to the cationic composition of the system; in K homoionic system, montmorillonite transformed rapidly into illite/montmorillonite with about 40% expandable layers at 300°C and in a mixed cation system with Ca and K, it reacted gradually to random illite/montmorillonites with increasing temperature. These data indicate that the cation-exchange process of a natural pore solution plays an important role in the gradual transformation of detrital montmorillonite to illite.
Interlayer Cations as Reaction Directors in the Transformation of Limonene on Montmorillonite
Authors: Frenkel M. , Heller-Kallai L. 
Published: September 2006

AbstractClays may catalyze chemical reactions by acting as Brönsted acids, Lewis acids, and/or Lewis bases. The changes occurring when limonene (p-menthadiene) is heated in the presence of montmorillonite illustrate how Brönsted and Lewis acidity may operate competitively, the nature of the interlayer cations determining which reaction dominates. The rate at which the starting material disappears increases with the acidity of the clay, which depends upon the interlayer cations (Na < Mg < Al < H). The concentration of disproportionation and isomerization products reaches a maximum after reaction times which decrease with increasing surface acidity of the clay, p-cymene is produced by oxidation in concentrations inversely related to the surface acidity of the clay. The course of the chemical reaction can thus be steered in the preferred direction by an appropriate choice of interlayer cations.
Crystal Structure of Cronstedtite-2H2
Authors: Geiger Charles A. , Henry Diane L. , Bailey S. W. , Maj Joseph J. 
Published: September 2006

AbstractThe crystal structure of a magnesian cronstedtite-2H2 from Pribram, Czechoslovakia, was refined in space group C1 to a residual of 5.4% with 1832 independent reflections. Tetrahedral ordering between Fe3+ and Si is judged to be complete on the basis of electron density maps, the first confirmation of such ordering in a layer silicate. Octahedral cations are disordered on the M sites. Mean T-O bond lengths do not confirm the tetrahedral ordering, perhaps due to tetrahedral distortion in order to relieve the extreme corrugation of the sheet that would arise from ordering of such different size cations.In the initial stages of refinement the structure of the crystal under study could not be described adequately on the basis of a single 2H2 polytype. The structure contains two kinds of 2H2 domains that appear shifted by b/3 relative to one another due to a mistake in the interlayer stacking sequence. This mistake of zero shift (the normal 2H2 polytype consists of alternating —b/3 and +b/3 shifts) affects only the tetrahedral sheets. It creates adjacent enantiomorphic domains of 2H2 packets such that domains with small Si tetrahedra sit above larger Fe3+-rich tetrahedra and vice versa. This mechanism to relieve strain may indeed be the cause of the stacking mistakes. A third kind of domain contains regions in which the sense of tetrahedral rotation is reversed, giving rise to split basal oxygens on electron density maps. This multiple domain model best explains extra atomic positions observed on Fourier maps, lack of streaking of k ≠ 3n reflections, and possible nonintegral “satellitic” reflections observed on Weissenberg films.
Role of Ferric Iron in the Oxidation of Hydrocortisone by Sepiolite and Palygorskite
Authors: Cornejo J. , Hermosin M. C. , White J. L. , Barnes J. R. , Hem S. L. 
Published: September 2006

AbstractThe role of adsorbed and structural Fe3+ in palygorskite and sepiolite with respect to the oxidation of hydrocortisone in aqueous suspension has been evaluated using electron spin resonance and UV-visible spectroscopy. Natural surface-adsorbed Fe3+ showed an important activity in the oxidation process, although smaller than octahedral Fe3+. The kinetics of oxidative degradation of hydrocortisone by palygorskite appear to be composed of two apparent first order reactions which may be associated with two kinds of sites for Fe in palygorskite. The lower oxidizing power of sepiolite for hydrocortisone degradation is due to its very low Fe3+ content.
Hydrothermal Reactions of Strontium and Transuranic Simulator Elements with Clay Minerals, Zeolites, and Shales
Authors: Komarneni Sridhar , White William B. 
Published: September 2006

AbstractReactions of Sr, La, and Nd (the latter two elements simulating Am and Cm) with potential backfill minerals for radioactive waste storage and with repository wall rocks, such as shale, were investigated under simulated repository conditions of 200° and 300°C for 12 weeks under a confining pressure of 30 MPa. The solid and solution reaction products were characterized to determine the nature and extent of reaction. Chlorite, illite, kaolinite, montmorillonite, mordenite, and clinoptilolite and four shales removed as much as 61.2 and 98.5% of the added SrCl2 and Sr(OH)2 from solution, respectively, by ion exchange and/or by forming new strontium compounds such as SrAl2Si2O8, Sr2MgSi2O7, SrCO3 (strontianite), and SrAl2Si4O12·2H2O (Sr-wairakite). The formation of these sparingly soluble Sr phases by the reaction of the soluble Sr compounds with such backfill materials indicates that the backfill may serve as a barrier during the thermal period of the waste in the life of a repository. These same minerals and shales removed as much as 99.99% of the added La or Nd from solution at 300°C by forming new phases such as LaOHCO3, NdOHCO3, and possibly La or Nd oxides and hydroxides. Zeolites reacted with La and Nd to form smectite. Thus, if La and Nd truly simulate the reactivity of Am and Cm, properly designed backfills can serve as a barrier to the migration of transuranic elements of nuclear wastes.
Clays, Cations, and Geophysical Log Response of Gas-Producing and Nonproducing Zones in the Gammon Shale (Cretaceous), Southwestern North Dakota
Authors: Gautier Donald L. , Starkey Harry C. , Takahashi Kenneth I. 
Published: September 2006

AbstractThe Upper Cretaceous Gammon Shale has served as both source bed and reservoir rock for accumulations of natural gas. Gas-producing and nonproducing zones in the Gammon Shale are differentiated on the basis of geophysical log interpretation. To determine the physical basis of the log responses, mineralogical, cation-exchange, textural, and chemical analyses were conducted on core samples from both producing and nonproducing portions of a well in the Gammon Shale from southwestern North Dakota. Statistical treatment (2 sample t-test and discriminant function analysis) of the laboratory data indicate that the producing and nonproducing zones differ significantly in mixed-layer clay content (7 vs. 12%), weight proportion of the clay-size (0.5-1.0 μm) fraction (5.3 vs. 6.3%) ratio of Ca2+ to Na+ extracted during ion exchange (1.4 vs. 1.0), and abundance of dolomite (10 vs. 8%). The geophysical logs apparently record subtle differences in composition and texture which probably reflect variations in the original detrital constituents of the Gammon sediments. Successfully combining log interpretation and clay petrology aids in understanding the physical basis of log response in clay-rich rocks and enhances the effectiveness of logs as predictive geologic tools.
Reactions of Alcohols with Alkenes over an Aluminum-Exchanged Montmorillonite
Authors: Adams J. M. , Clement D. E. , Graham S. H. 
Published: September 2006

AbstractThe reaction of 2-methyl pent-2-ene with primary alcohols (C1-C18) at 95°C over an Al-montmorillonite gave yields of 20–90% of ethers of the type R-O-C(CH3)2C3H7. Lower yields were produced if secondary alcohols were employed, and tertiary alcohols gave only a trace of this ether. When a variety of alkenes was reacted with butan-1-ol at 95°C over a similar catalyst, no reaction occurred unless the alkene was capable of forming a tertiary carbonium ion immediately upon protonation. In this case the product was the tertiary ether t-R-O-nC4H9. However, at a reaction temperature of 150°C a variety of products were formed including (1) ether by the attack of butanol on the carbonium ions produced either directly from protonation of the alkenes or by hydride shift from such an ion, (2) alkenes by the attack of n-C4H9+ ions (derived from protonation and dehydration of butanol) on the alkene, (3) di-(but-1-yl) ether by dehydration of the butanol, and (4) small amounts of alcohol by hydration of the alkene. The differences in reactivity below and above 100°C are related directly to the amount of water present in the interlayer space of the clay and the degree of acidity found there. Although the clay behaves as an acid catalyst, the reactions are far cleaner (more selective) than comparable reactions catalyzed by sulfuric acid.
Intergradient Vermiculite-Kaolin Mineral in a Korean Ultisol
Authors: Wada Koij , Kakuto Yasuko 
Published: September 2006

AbstractA 14-Å mineral coexisting with kaolin minerals, mica, and gibbsite in a Korean Ultisol and showing X-ray powder diffraction features of “chloritized” vermiculite was studied by a combination of methods. The 14-Å mineral collapsed on saturation with K+ after extraction with hot 1/3 M sodium citrate, but the Si/Al ratio of the extracted material was close to 1.0 and kaolin minerals dissolved, as indicated by difference infrared spectroscopy. The 14-Å mineral was also collapsed by heating at or above 350°C. The difference infrared spectra and the X-ray powder diffraction patterns indicated that two forms of kaolin mineral are present that differ in thermal stability; one decomposed by heating at or below 375°C and the other by heating above 375°C. The former kaolin mineral is probably associated with vermiculite and the latter is present as a discrete form. The 14-Å mineral was inferred to be an intergradient vermiculite-kaolin mineral, in which most vermiculite layers each partially transform into double kaolin layers, and to represent an intermediate phase during the transformation of 2:1 to 1:1 layer silicates in acid soils.
Clay Minerals in Mixtures: Sample Preparation, Analysis, and Statistical Interpretation
Authors: Gold C. M. , Cavell P. A. , Smith D. G. W. 
Published: September 2006

AbstractA method of clay mineral sample preparation for electron microprobe analysis has been developed in which a film of clay plus 10–12 wt. % colloidal graphite is deposited on a porous ceramic disc using a specially designed suction device. Correction procedures are used to obtain quantitative elemental analyses representing the average chemical composition of the prepared sample. A statistical technique is employed to estimate the most likely proportions of clay minerals representing the known composition. Chemical compositions of clay minerals are presented in terms of five coordinates (“Si,” “Al,” “Mg,” “K,” and “Fe”). Using literature data, the chemical compositions of 13 different clay mineral groupings were defined statistically by their multivariate means and variance-covariance matrices. A correlation parameter, χ2, was calculated to compare the chemical composition of a sample with that of any mixture of the defined clay mineral groupings, the minimum χ2 indicating the best-fit mixture.From chemical analyses of artificial mixtures only approximate clay mineral proportions could be determined when the various clay mineral groupings had been defined statistically from literature analyses. The best results were obtained when the actual compositions of the end-members forming the artificial mixtures replaced the statistical definitions. Tests of the estimation procedure on clay mineral mixtures for which chemical compositions and corresponding clay mineral proportions were found in the literature, indicate that the technique has appreciable merit.
Structure of a Vermiculite-Aniline Intercalate
Authors: Slade P. G. , Stone P. A. 
Published: September 2006

AbstractA vermiculite-aniline intercalate with a basal spacing of 14.78 Å was investigated by one- and two-dimensional X-ray diffraction methods. The intercalate, prepared by ion exchange between Na-saturated vermiculite from Llano, Texas, and a 1% aniline hydrochloride solution, contains only one aniline cation per single layer cell. A reduced effective cell-charge is believed to be responsible for this. Structure factor calculations were made in space group C2/c and with unit cell dimensions of a = 5.33, b = 9.18, c = 29.78 Å, and β = 97.0°. However, extra reflections in the a*b* plane, which are similar to those in a vermiculite-benzidine intercalate, showed that after aniline intercalation the true unit cell became primitive. The aniline cations are distributed statistically over equivalent crystallographic sites in the interlayer space. The organic molecules are orientated with their planes vertical and their nitrogen atoms over the projected centers of the ditrigonal cavities into which they key. The aniline cations form ordered arrays upon the silicate layers by packing into rows. Perpendicular to [010], populated and vacant rows alternate. Along populated rows aromatic ring planes are alternately parallel and perpendicular to [010]. With small adjustments this model is similar to that of benzidine-vermiculite.
Activity/Composition Relations among Silicates and Aqueous Solutions: II. Chemical and Thermodynamic Consequences of Ideal Mixing of Atoms on Homological Sites in Montmorillonites, Illites, and Mixed-Layer Clays
Authors: Aagaard Per , Helgeson Harold C. 
Published: September 2006

AbstractThe activities of thermodynamic components of clay minerals corresponding in composition to pyrophyllite, muscovite, paragonite, and margarite were computed from chemical analyses reported in the literature assuming ideal mixing of atoms on homological sites in the minerals. These activities were then used to generate stability fields for smectites, illites, and mixed-layer clays on logarithmic activity diagrams representing equilibrium among minerals and aqueous solutions at 25°C and 1 bar. Comparative analysis indicates that the approach affords close approximation of both mineral and water compositions in geologic systems.