bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for Halloysite Formation from Weathering of Ferruginous Chlorite
Authors: Cho Hi Doo , Mermut A. R. 
Published: August 2006

AbstractEvidence of chlorite weathering to halloysite appears to be limited. Trioctahedral ferruginous chlorite occurring in granitic rocks and in situ altered phases isolated from the horizons of two soils in southern Korea were studied by scanning and transmission electron microscope (SEM, TEM), chemical, and X-ray diffraction (XRD) techniques to determine the mechanism of alteration and nature of alteration products. Chlorites were entirely converted to halloysite, kaolinite, and Fe-oxyhydroxides in the thick Bt horizon. In the E and BC horizons, in addition to 1:1 silicate clays and Fe-oxyhydroxides, chlorite-like and intergradient vermiculite-kaolin minerals were also found. Total chemical analysis of chlorite flakes revealed losses of substantial amounts of Fe and Mg. Large parallel sets of galleries suggested extensive exfoliation and expansion of chlorite flakes. Tubular halloysite formed bridges between the walls of galleries. The SEM and TEM analyses showed very distinct coatings (0.2–0.3 μm thick) of Fe-oxyhydroxides above and below the surface of galleries that consisted of rounded, sub-rounded, elongated, ultramicrocrystalline particles (goethite and hematite). The 1:1 mineral species found in the thick Bt horizon had a tubular and crumpled lamellar morphology. The presence of Fe likely creates a misfit between tetrahedral and octahedral sheets and results in the morphology of the 1:1 clays observed under SEM and TEM. The presence of intergradient minerals between chlorite and 1:1-type clays in the surface and transitional BC horizon suggests that, in addition to losses of OH sheet -Fe and -Mg, the chlorite with mostly Al-octahedra is partly transformed to double 1:1 silicate clays and intergradient minerals.
Reduction of Structural Iron in Ferruginous Smectite by Free Radicals
Authors: Gan Huamin , Stucki Joseph W. , Bailey George W. 
Published: August 2006

AbstractThe oxidation state of structural iron greatly influences the physical-chemical properties of clay minerals, a phenomenon that may have significant implications for pollutant fate in the environment, for agricultural productivity, and for industrial uses of clays. Knowledge of redox mechanisms is fundamental to understanding the underlying basis for iron's effects on clays. Past studies revealed that the extent of Fe reduction varied depending on the reducing agent used, but this variation may not have been a simple function of the reduction potential of the reducing agent. The objective of this study was to identify the relationship between the Fe reduction mechanism and free radical activity in the reducing agent. Several reducing agents and their mixtures with the Na-saturated, 0.5 to 2 μm size fraction of ferruginous smectite (SWa-1) were analyzed by electron spin resonance (ESR) spectroscopy to determine the presence of unpaired electrons or free radicals. Only Na2S2O4 exhibited paramagnetic free-radical behavior with a signal at about g = 2.011, which was attributed to the sulphoxylate (S02− ·) free radical. The free radical was labile in aqueous solution, and the ability of Na2S2O4 solution to reduce structural Fe in the smectite decreased with age of the solution and paralleled the disappearance of the free radical signal in the ESR spectrum. The paramagnetic species was preserved and enhanced if Na2S2O4 was added to the clay suspension, indicating that either the clay surface stabilized the SO2− · radical or the additional unpaired electrons were produced in the clay structure.
Vibrational Probe Studies of Water Interactions with Montmorillonite
Authors: Johnston C. T. , Sposito G. , Erickson C. 
Published: August 2006

AbstractInteraction of water with montmorillonite exchanged with Na+, K+, Co2+, and Cu2+ cations as a function of water content was examined using an FTIR/gravimetric cell designed to collect spectroscopic and sorption data simultaneously. Correlation of water desorption isotherms with infrared spectra of the clay-water complex showed that the position of the HOH bending band of water decreased as a function of water content. The largest decreases in frequency were observed for Cu2+ and Co2+; smaller decreases were found for Na+ and K+. In addition, the molar absorptivity of sorbed water increased upon decreasing the water content. The decrease in frequency and the concomitant increase in molar absorptivity were attributed to polarization effects on the sorbed water molecules by exchangeable cations. The interference fringes of a self supporting clay film permitted d-spacings to be determined optically and, therefore, changes in frequency, molar absorptivity, and water sorption behavior to be related directly to changes in interlayer spacing. The d-spacings obtained from the interference fringes were consistently larger by approximately 0.5 Å than those determined using powder XRD.
Porosity-Size Relationship of Drilling Mud Flocs: Fractal Structure
Authors: Huang Hening 
Published: August 2006

AbstractThe porosities of flocs formed from a used drilling mud were determined by measuring sizes and settling speeds of individual flocs. These flocs were produced in a Couette-type flocculator under a variety of combinations of fluid shear and solid concentrations. In the calculation of floc porosities, a floc settling model was employed that can consider the effects of creeping flow through a floc on its settling speed. Results show that floc structure can be well described as a fractal with a fractal dimension of 1.53–1.64 for the floc size range tested. The effects of flocculation conditions, such as fluid shear and solid concentration, on floc porosity and structure were examined. It was found that floc porosity and fractal dimension were not influenced by solid concentration, but they increased as fluid shear decreased. Empirical expressions for the porosity of drilling mud flocs are obtained from both the floc settling model and Stokes’ law. For solid volume fraction in flocs, the relative difference between these two expressions could be as much as 38%. However, the fractal dimensions estimated based on the two settling models are nearly the same.
X-Ray Identification of One-Layer Illite Varieties: Application to the Study of Illites Around Uranium Deposits of Canada
Authors: Drits V. A. , Weber F. , Salyn A. L. , Tsipursky S. I. 
Published: August 2006

AbstractStructural and diffraction criteria for distinguishing between t-1M, c-1M, m-1M, and 3T illite varieties are described. The t-1M illite corresponds to a one-layer monoclinic structure with vacant transsites. The c-1M illite has vacant cis-octahedra forming one of two symmetrically independent point systems; the other cis-octahedra as well as the trans-octahedra are occupied; and the m-1M illite corresponds to the structure in which cations are statistically distributed over available trans- and cis-sites. For t-1M, c-1M, and m-1M, the values of |c cos β/a| are equal to 0.39–0.41, 0.29–0.31, and 0.333, respectively. Application of these criteria demonstrates that illite samples described in the literature as the 3T polytype usually are c-1M instead. The relatively common occurrence of c-1M illite in association with t-1M and 2M1 polytypes has been recognized in illite from hydrothermal alterations around uranium deposits located in the Athabasca basement (Saskatchewan, Canada). The c-1M illite from these deposits was previously described as 3T one.
Origin of the Mg-Smectite at the Cretaceous/Tertiary (K/T) Boundary at Stevns Klint, Denmark
Authors: Elliott W. Crawford 
Published: August 2006

AbstractThe clay mineralogy and major element geochemistry of four distinct layers within the Cretaceous/Tertiary (K/T) boundary marl (i.e., II, IIIa, IIIb, and IV) at Stevns Klint, Denmark, including “impact layer” (layer IIIa), were examined, and there was not a marked change in the clay mineralogy throughout this K/T boundary marl. A magnesium smectite (i.e., Mg-smectite) was the predominant clay mineral at the K/T boundary not only at Stevns Klint and at Nye Kløv; it was also found to be the predominant clay mineral in the K/T boundary at Karlstrup Quarry. In addition, Mg-smectite was found in a smectitic marl 32 meters below the K/T boundary at the Limhamn Quarry (near Malmö, Sweden), and it did not have anomalous concentrations of iridium or other siderophile trace elements. Given its occurrence in a Maastrichtian marl, it is therefore argued that the Mg-smectite is not derived from meteorite impact.The rare earth element (REE) signatures of the Mg-smectites ranged from being comparable to the North American Shale Standard (NASC) to being one-half an order of magnitude depleted relative to NASC. One Mg-smectite collected from layer IIIb, immediately above the “impact/red layer,” was depleted in REE by one order of magnitude relative to NASC, and these levels of REE are comparable to those of smectite and illite/smectite (I/S) formed authigenically in bentonites and K-bentonites, respectively. Thus, the REE data suggest this Mg-smectite in all likelihood was formed authigenically from a glassy precursor. The presence of the low levels of REE of the Mg-smectite in the layer IIIb has no particular significance other than to suggest that this Mg-smectite separate was the least contaminated with illite or apatite having higher REE levels. With better separation, the other Mg-smectites would be expected to have comparably low levels of REE. Given the presence of the Mg-smectite throughout the K/T boundary and in Maastrichtian and Danian marls, the Mg-smectite is thought to be of volcanic origin. However, is not certain whether the Mg-smectite formed from volcanic glass deposited at the K/T boundary or whether it was formed from volcanic glass as young as late Cretaceous.
The Near-Infrared Combination Band Frequencies of Dioctahedral Smectites, Micas, and Illites
Authors: Post James L. , Noble Paul N. 
Published: August 2006

AbstractThe highest frequency near-infrared (NIR) combination bands for specimens of four species of mica—montmorillonite-beidellite, illite, chlorite, and kaolinite—were correlated with respect to Al2O3 content. A direct linear correlation was found between the combination band positions and the Al2O3 contents of the montmorillonite-beidellite series, which may be given as: ν̄ cm−1 = (5.38 ± 0.04) (% Al2O3) + (4412.8 ± 0.9). A similar linear correlation for muscovite is: ν̄ cm−1 = (6.10 ± 0.25) (% Al2O3) + (4434.1 ± 8.3).Possible NIR band interferences are shown for different mineral mixtures, along with the correlation of different illites with muscovite. No combination bands were found in the frequency region 4425 cm−1 to 4625 cm−1 for specimens in which the Al2O3 content was only in the tetrahedral layer sites.
The Formation of Illitic Clays from Kaolinite in KOH Solution from 225°C to 350°C
Authors: Huang Wuu-Liang 
Published: August 2006

AbstractKaolinite was converted into illitic clays in a 2.58 m KOH solution in gold capsules using cold-seal pressure vessels at 225°, 250°, 300°, and 350°C and 500 bars. The XRD shows that the major reaction products are illitic clays with no interlayer expandability. The TEM shows that the illitic clays appear mainly platelet-like with a K/Si ratio close to that of muscovite/illite. The extent of the conversion was monitored by measuring the XRD peak ratio of muscovite (illite) and kaolinite in quenched run products. The results reveal that kaolinite converts to muscovite/illite in the KOH solution at an initial rate two to three orders of magnitude faster than that of similar reactions at near-neutral conditions.
Declining Death Rates From Hyperglycemic Crisis Among Adults With Diabetes, U.S., 1985–2002
Authors: Wang Jing , Williams Desmond E. , Narayan K.M. Venkat , Geiss Linda S. 
Published: August 2006

OBJECTIVE—To examine trends in death rates for hyperglycemic crisis (diabetic ketoacidosis or hyperglycemic hyperosmolar state) among adults with diabetes in the U.S. from 1985 to 2002.
RESEARCH DESIGN AND METHODS—Deaths with hyperglycemic crisis as the underlying cause were identified from national mortality data. Death rates were calculated using estimates of adults with diabetes from the National Health Interview Survey as the denominator and age adjusted to the 2000 U.S. population. The trends from 1985 to 2002 were tested using joinpoint regression analysis.
RESULTS—Deaths due to hyperglycemic crisis dropped from 2,989 in 1985 to 2,459 in 2002. During the time period, age-adjusted death rates decreased from 42.4 to 23.8 per 100,000 adults with diabetes (4.4% decrease per year, P for trend &lt;0.01). Death rates declined in all age-groups, with the greatest decrease occurring among individuals aged ≥65 years. Age-adjusted death rates fell for all race-sex subgroups, with black men experiencing the smallest decline. About one-fifth of deaths occurred at home or on arrival at the hospital, and the death rates for hyperglycemic crisis occurring at these places declined only modestly over time (2.1% decrease per year, P for trend = 0.049).
CONCLUSIONS—Overall death rates due to hyperglycemic crisis among adults with diabetes have declined in the U.S. However, scope for further improvement remains, especially to further reduce death rates among black men and to prevent deaths occurring at home.
Adherence to Preventive Medications
Authors: Walker Elizabeth A. , Molitch Mark , Kramer M. Kaye , Kahn Steven , Ma Yong , Edelstein Sharon , Smith Kellie , Johnson Mariana Kiefer , Kitabchi Abbas , Crandall Jill ,   for the Diabetes Prevention Program Research Group
Published: August 2006

OBJECTIVE—To evaluate barriers to and strategies for medication adherence and predictors of adherence and the primary outcome in the Diabetes Prevention Program (DPP).
RESEARCH DESIGN AND METHODS—Within a randomized, controlled primary prevention study for type 2 diabetes, we collected data on study medication adherence, its predictors, and health outcomes in 27 clinical centers across mainland U.S. and Hawaii. Medication arm participants included 2,155 adults with impaired glucose tolerance randomly assigned to either metformin or matched placebo treatment arms. Structured interviews were used to promote medication adherence and to collect data regarding adherence. Adherence was measured by pill count. The primary DPP outcome of type 2 diabetes was assessed by fasting plasma glucose and oral glucose tolerance test.
RESULTS—Older age-groups were more adherent than the youngest group (P = 0.01) in the metformin group. The most frequently reported barrier to adherence was “forgetting” (22%). Women reported more adverse effects of metformin (15 vs. 10%, P = 0.002) in the metformin group. Odds of nonadherence increased as participants reported more than one barrier (odds ratio 19.1, P &lt; 0.001). Odds of adherence increased as participants reported multiple strategies to take medication (2.69, P &lt; 0.0001). There was a 38.2% risk reduction for developing diabetes for those adherent to metformin compared with those adherent to placebo (P &lt; 0.0003).
CONCLUSIONS—DPP medication adherence results are unique in primary prevention for a chronic disease in a large multiethnic sample. Our finding that adherence was associated with risk reduction for diabetes supports the development of brief interventions in clinical settings where medication adherence is a challenge.
Effect of Weight Loss With Lifestyle Intervention on Risk of Diabetes
Authors: Hamman Richard F. , Wing Rena R. , Edelstein Sharon L. , Lachin John M. , Bray George A. , Delahanty Linda , Hoskin Mary , Kriska Andrea M. , Mayer-Davis Elizabeth J. , Pi-Sunyer Xavier , Regensteiner Judith , Venditti Beth , Wylie-Rosett Judith ,   for the Diabetes Prevention Program Research Group
Published: August 2006

OBJECTIVE—Diabetes Prevention Program (DPP) participants randomized to the intensive lifestyle intervention (ILS) had significantly reduced risk of diabetes compared with placebo participants. We explored the contribution of changes in weight, diet, and physical activity on the risk of developing diabetes among ILS participants.
RESEARCH DESIGN AND METHODS—For this study, we analyzed one arm of a randomized trial using Cox proportional hazards regression over 3.2 years of follow-up.
RESULTS—A total of 1,079 participants were aged 25–84 years (mean 50.6 years, BMI 33.9 kg/m2). Weight loss was the dominant predictor of reduced diabetes incidence (hazard ratio per 5-kg weight loss 0.42 [95% CI 0.35–0.51]; P &lt; 0.0001). For every kilogram of weight loss, there was a 16% reduction in risk, adjusted for changes in diet and activity. Lower percent of calories from fat and increased physical activity predicted weight loss. Increased physical activity was important to help sustain weight loss. Among 495 participants not meeting the weight loss goal at year 1, those who achieved the physical activity goal had 44% lower diabetes incidence.
CONCLUSIONS—Interventions to reduce diabetes risk should primarily target weight reduction.
Enhancement of molecular polarizabilities by the push-pull mechanism; a DFT study of substituted benzene, furan, thiophene and related molecules
Authors: Hinchliffe Alan , Mkadmh Ahmed , Nikolaidi Beatrice , Soscún Humberto , Abu-Awwad Fakhr 
Published: August 2006

Abstract
We report Density Functional Theory (DFT) studies of the dipole polarizabilities of benzene, furan and thiophene together with a number of substituted and related systems. All geometries were optimized (and characterized) at the B3LYP/6-311g(2d,1p) level of theory and polarizabilities then calculated with B3LYP/6-311++G(2d,1p). For the R-ring systems we find group polarizabilities in the order R = NO2 ∼ OCH3 ∼ CN ∼ CHO > NH2 > OH > H = 0. For systems R-ring-R, 〈α〉 differs little from the additivity model, with small positive and negative increments. For systems D-ring-A (where D and A are deactivating and activating groups) we find a positive enhancement to 〈α〉 over and above the value expected on the basis of pure additivity for all pairs A and D studied. This enhancement can be increased greatly by extending the length of the conjugated chain to D-ring-CH=CH-ring-A and D-ring-N=N-ring-A systems. Empirical models of polarizability such as AM1 agree badly with the DFT calculations in an absolute sense but give excellent statistical correlation coefficients. Calculated 〈α〉’s also agree well in a statistical sense with the molecular volumes calculated from molecular mechanics force fields
Analysis of the results in terms of the π electrons alone is not satisfactory.
NK cell-based immunotherapies against tumors
Authors: Radons Jürgen , Stangl Stefan , Multhoff Gabriele 
Published: August 2006

Abstract
Natural killer (NK) cells provide the first line of defence against pathogens and tumors. Their activation status is regulated by pro-inflammatory cytokines and by ligands that either target inhibitory or activating cell surface receptors belonging to the immunoglobulin-like, C-type lectin or natural cytotoxicity receptor families. Apart from non-classical HLA-E, membrane-bound heat shock protein 70 (Hsp70) has been identified as a tumor-specific recognition structure for NK cells expressing high amounts of the C-type lectin receptor CD94, acting as one component of an activating heterodimeric receptor complex. Full-length Hsp70 protein (Hsp70) or the 14-mer Hsp70 peptide T-K-D-N-N-L-L-G-R-F-E-L-S-G (TKD) in combination with pro-inflammatory cytokines enhances the cytolytic activity of NK cells towards Hsp70 membrane-positive tumors. Based on these findings cytokine/TKD-activated NK cells were adoptively transferred in tumor patients. These findings were compared to results of clinical trials using cytokine-activated NK cells.
Not at risk — Nevertheless a pressure ulcer
Authors: Lahmann Nils , Halfens Ruud , Dassen Theo 
Published: August 2006

Abstract
When conducting prevalence surveys pressure ulcers were found in participants clearly identified not to be at risk. This article determines and analyses persons in German hospitals and nursing homes who suffer from pressure ulcers but are not at risk. In the years 2002, 2003 and 2004 there were 7,097 nursing home residents and 23,966 hospital patients examined in annual pressure ulcer prevalence surveys. A risk assessment according to the Braden Scale was performed for each participant on the day of the survey. “Not at risk” participants were defined by Braden score cut-off > 20 points. There were 440 of 3,012 (14.6%) persons with pressure ulcer who were considered not to be at risk. In hospitals, 16.1% of all patients with pressure ulcers were not at risk, in nursing homes it was 8.2%. A high variance between medical specialties and individual institutions was found in the number of those not at risk but with pressure ulcer. In the group not at risk, persons with and without a pressure ulcer differed regarding activity and friction and shear in nursing homes. In hospitals those persons differed regarding age and all single items of the Braden scale apart from sensory perception. Pressure ulcers that are more severe, located at the hip or lower back or the origin of which is unknown are more likely to be considered to be at risk by the Braden risk assessment tool.
The results may indicate insufficient abilities of the Braden scale for certain kind of pressure ulcer wounds.
An intracrine view of angiogenesis
Authors: Re Richard N. , Cook Julia L. 
Published: August 2006

AbstractAngiogenesis, the generation of new blood vessels from pre‐existing vessels, is an integral component of wound healing, responses to inflammation and other physiologic processes. It is also an essential part of tumor growth; in the absence of new vessel formation, tumors cannot expand beyond a small volume. Although much is known about angiogenesis and its regulation, there is no overall theory that describes or explains this process. It is here suggested that the intracrine hypothesis, which ascribes to certain extracellular signaling peptides (whether hormones, growth factors, DNA‐binding proteins or enzymes) a role in both intracellular biology and extracellular signaling, can contribute to a more general understanding of angiogenesis. Intracrine factors participate in angiogenesis in the following ways: (1) they can act within the cells that synthesized them (type I intracrine action), (2) they can be secreted and then taken up by their cell of synthesis to act intracellularly (type II intracrine action ), or (3) they can be secreted and internalized by a distant target cell (type III intracrine action). The parallels between the intracrine growth factor mechanisms cancer cells employ in stimulating their own growth and the mechanisms operative in endothelial cell proliferation during angiogenesis (“intracrine reciprocity”) are discussed. Collectively, these explorations lead to testable hypotheses regarding the regulation of normal and pathological angiogenesis, and point to similarities between tumor‐induced angiogenesis and tissue differentiation. BioEssays 28: 943–953, 2006. © 2006 Wiley periodicals, Inc.