bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated Fitting of X-Ray Powder Diffraction Patterns from Interstratified Phyllosilicates
Authors: Yuan Hongji , Bish David L. 
Published: January 2011

AbstractNEWMOD®, developed by R.C. Reynolds, Jr., has been an important tool for evaluating quantitatively X-ray diffraction (XRD) patterns from interstratified clay minerals for more than 20 years. However, a significant drawback to the NEWMOD® approach is that analyses are done by forward simulation, making results sensitive to user input and starting-model assumptions. In the present study, a reverse-fitting procedure was implemented in a new program, FITMOD, which automatically minimizes the differences between experimental and simulated XRD patterns. The differences are minimized by varying model parameters (such as Reichweite, crystal-size distribution, cation content, type of disorder, etc.) using the downhill simplex method. The downhill simplex method is a non-linear optimization technique for determining minima of functions. This method does not require calculation of the derivatives of the functions being minimized, an important consideration with many of the parameters in NEWMOD- type simulations. Instead, the downhill simplex method calculates pseudo-derivatives by evaluating sufficient points to define a derivative for each independent variable. The performance of FITMOD was evaluated by fitting a series of synthetic XRD patterns generated by NEWMOD+, yielding agreement factors, Rwp, of <0.3%. As long as the correct interstratified system was specified (e.g. illite-smectite), excellent fits were obtained irrespective of the starting parameters for the simulations. FITMOD was also tested using experimental XRD patterns, which gave very good fits, in agreement with previously published results. The optimization routine yields good fits for both synthetic and experimental XRD profiles in a reasonable time, with the possibility of varying all important structural parameters. FITMOD automatically provides optimum fits to experimental XRD data without operator bias, and fitting efficiency and accuracy were, therefore, significantly improved.
Evolution of Boron and Nitrogen Content During Illitization of Bentonites
Authors: Środoń Jan 
Published: January 2011

AbstractThe incorporation of boron (B) and nitrogen (N) into illite is the key demand-side process responsible for the diagenetic budget of these elements in sedimentary basins, with important implications for pore-water chemistry, natural-gas composition, and borehole geophysics. The purpose of the present study was to take advantage of recent advances in quantitative mineral analysis of sedimentary rocks which have opened new possibilities for investigating this particular process. In order to avoid complications with recycled (detrital) N and B, clays from pyroclastic horizons of sedimentary rocks (bentonites) were used. The B and N contents in illite-smectite were measured in samples from different sedimentary basins, representing a complete range of diagenetic alteration. The bulk-rock chemical measurements, performed on raw rock samples in order to avoid any loss of exchangeable B and N, were referred to the contents of illite-smectite clays and to the content of illite alone, both measured by a combination of XRD and chemistry-based techniques.Both B and N (as NH4) are present in illite, so their contents in illite-smectite clay increase in a more or less linear manner with progressing illitization. Thus, during diagenesis, the illite-smectite clay is a net consumer of B and N from the pore water. The amount of N in individual illite layers decreases during diagenesis and the amount of B either decreases or remains stable. Bentonitic illite must acquire both B and N from outside of the bentonite bed. In one diagenetic cycle, bentonitic illite fixes up to 800–1000 ppm B and up to >1% N expressed as (NH4)2O, corresponding to >20% of the fixed cation sites.
Illitization of Kaolinite: The Effect of Pressure on the Reaction Rate
Authors: Mantovani Marco , Becerro Ana Isabel 
Published: January 2011

AbstractStudies of the paragenesis of authigenic illite in arkosic sandstones of various regions and ages have revealed that the illitization of kaolinite is an important reaction accounting for the formation of authigenic illite in sandstones during burial diagenesis. The illitization of kaolinite takes place at an intermediate burial depth of 3–4 km, where pressure can reach values of 100 MPa (≈ 1000 bars). The purpose of the present study was to analyze the effect of pressure on the rate of kaolinite illitization in alkaline conditions. Hydrothermal reactions were conducted on KGa-1b kaolinite in KOH solution at 300°C and under pressures of 500, 1000, and 3000 bars for 1 to 24 h. The visual examination of the X-ray diffraction (XRD) patterns indicated a notable influence of pressure on the reaction rate. Molar percentages of muscovite/illite formed at each time interval were calculated from the analysis of two diagnostic XRD peaks, representing the 060 reflections of kaolinite and muscovite/illite. The data were modeled to obtain the initial rate of conversion at each pressure. The results indicated that the initial rate of kaolinite to muscovite/illite conversion is one order of magnitude greater at 3000 bars than at 500 or 1000 bars. Comparison of these data with those in the literature show a faster conversion rate (several orders of magnitude) in an initially high-alkaline solution than in a near-neutral solution.
XAS Study of Fe Mineralogy in a Chronosequence of Soil Clays Formed in Basaltic Cinders
Authors: Baker Leslie L. , Strawn Daniel G. , Vaughan Karen L. , McDaniel Paul A. 
Published: January 2011

AbstractThe characterization of poorly crystalline minerals formed by weathering is difficult using conventional techniques. The objective of this study was to use cutting-edge spectroscopic techniques to characterize secondary Fe mineralogy in young soils formed in basaltic cinders in a cool, arid environment. The mineralogy of a chronosequence of soils formed on 2, 6, and 15 thousand year old basaltic cinders at Craters of the Moon National Monument (COM) was examined using synchrotron-based X-ray absorption fine structure (XAFS) spectroscopy in combination with selective extractions. Fe K-edge XAFS is useful for determining speciation in poorly crystalline materials such as young weathering products. Over 86% of Fe in the soil clay fractions was contained in poorly crystalline materials, mostly in the form of ferrihydrite, with the remainder in a poorly crystalline Fe-bearing smectite. The XAFS spectra suggest that ferrihydrite in the 15 ka soil clay is more resistant to ammonium oxalate (AOD) extraction than is ferrihydrite in the younger materials. Fe in the poorly crystalline smectite is subject to dissolution during citrate-bicarbonate- dithionite (CBD) extraction. The results indicate that relatively few mineralogical changes occur in these soils within the millennial time frame and under the environmental conditions associated with this study. Although the secondary mineral suite remains similar in the soils of different ages, ferrihydrite crystallinity appears to increase with increasing soil age.
Characterization of Organo-Bentonites Obtained from Different Linear-Chain Quaternary Alkylammmonium Salts
Authors: Erkan Ïlker , Alp Ïbrahim , Çelik Mehmet SabrÏ 
Published: January 2011

AbstractThe effects of surfactants on bentonites have been of great scientific interest for many years. Even though quaternary alkylammonium salts (QAS) have been studied, very few data are available on the comparative performance of different chain-length QAS for the modification of the surface properties and adsorption properties of bentonites. The objective of this study was to investigate the effect of chain length on the adsorption of cationic surfactants onto bentonite. The surface and adsorption properties of different chain-length QAS, i.e. hexadecyltrimethylammonium bromide (HTAB, C16), tetradecyltrimethylammonium bromide (TTAB, C14), and dodecyltrimethylammonium bromide (DTAB, C12), to produce organo- bentonites (OB) were studied. The concentrations of QAS were selected based on the cation exchange capacity (CEC) of the clay mineral. Zeta potential, swelling, and viscosity measurements and scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) analyses were used to explain the changes in surface properties. The results indicated that the best modification of bentonite was obtained using a 16-carbon chain length QAS (HTAB) in a 1:1 ratio of QAS to CEC. The basal spacing at this concentration was measured to be 22.19 Å, which also corresponded to the maximum adsorption density. The OB produced at this concentration showed the best hydrophobic character based on the swelling tests in toluene. The extent of hydrophobicity and adsorption density was correlated with the CEC and alkyl chain of the QAS. All these properties were used to elucidate the mechanism of modification governing the bentonite/QAS system.
Atomic Force Microscopy Method for Measuring Smectite Coefficients of Friction
Authors: Kosoglu Laura M. , Bickmore Barry R. , Filz George M. , Madden Andrew S. 
Published: January 2011

AbstractThe coefficient of friction of clay minerals at the micro-scale has generally not been studied due to difficulties in obtaining measurements in a bulk-soil volume undergoing shear at such small scales. Information on friction at the micro-scale may provide insight into grain-scale processes that operate in bulk samples or in natural faults. The objective of this study was to develop a method to measure the microscale friction coefficient of smectites. The experiments described show that the axial atomic force microscopy method can be adapted to easily obtain accurate coefficient of friction (μ) measurements for smectites from force curves involving colloidal probes. The method allows for the measurements to be performed over spatial scales of a few μm, can be carried out under dry conditions or a wide range of aqueous solutions, and requires no calibration beyond making a few microscopic measurements of the probe. This method provides measurements of micro-scale normal and shear forces between minerals, which can be used for a variety of applications such as the study of shear deformation, consolidation, and fault dynamics. Control tests of silica on mica (μ = 0.29±0.02) agree with literature values where limits indicate one standard deviation. Coefficient of friction values for wet and dry Na-montmorillonite were determined to be 0.20±0.03 and 0.72±0.03, respectively.
Reductive Degradation ofp,p′-DDT cy Fe(II) in Nontronite NAu-2
Authors: Fialips Claire I. , Cooper Nicola G. A. , Jones D. Martin , White Maggie L. , Gray Neil D. 
Published: January 2011

AbstractClay minerals are abundant in soils and sediments and often contain Fe. Some varieties, such as nontronites, contain as much as 40 wt.% Fe2O3within their molecular structure. Several studies have shown that various Fe-reducing micro-organisms can use ferric iron in Fe-bearing clay minerals as their terminal electron acceptor, thereby reducing it to ferrous iron. Laboratory experiments have also demonstrated that chemically or bacterially reduced clays can promote the reductive degradation of various organics, including chlorinated pesticides and nitroaromatics. Therefore, Fe-bearing clays may play a crucial role in the natural attenuation of various redox-sensitive contaminants in soils and sediments. Although the organochlorinated pesticidep,p′-DDT is one of the most abundant and recalcitrant sources of contamination in many parts of the world, the impact of reduced Fe-bearing clays on its degradation has never been documented. The purpose of the present study was to evaluate the extent of degradation ofp,p′-DDT during the bacterial reduction of Fe(III) in an Fe-rich clay. Microcosm experiments were conducted under anaerobic conditions using nontronite (sample NAu-2) spiked with p,p′-DDT and the metal-reducing bacteriaShewanella oneidensisMR-1. Similar experiments were conducted using a sand sample to better ascertain the true impact of the clayvs.the bacteria on the degradation of DDT. Samples were analyzed for DDT and degradation products after 0, 3, and 6 weeks of incubation at 30°C. Results revealed a progressive decrease inp,p′-DDT and increase inp,p′-DDD concentrations in the clay experiments compared to sand and abiotic controls, indicating that Fe-bearing clays may substantially contribute toward the reductive degradation of DDT in soils and sediments. These new findings further demonstrate the impact that clay materials can have on the natural attenuation of pollutants in natural and artificial systems and open new avenues for the passive treatment of contaminated land.
DPP-4 inhibition increases GIP and decreases GLP-1 incretin effects during intravenous glucose tolerance test in Wistar rats
Authors: Freyse Ernst-Joachim , Berg Sabine , Kohnert Klaus-Dieter , Heinke Peter , Salzsieder Eckhard 
Published: January 2011

Abstract
GIP metabolite [GIP (3–42)] and GLP-1 metabolite [GLP-1 (9–36) amide] have been reported to differ with regard to biological actions. Systemic DPP-4 inhibition can therefore reveal different actions of GIP and GLP-1. In catheter wearing Wistar rats, insulinotropic effects of equipotent doses of GIP (2.0 nmol/kg) and GLP-1 (7–36) amide (4.0 nmol/kg) and vehicle were tested in the absence/presence of DPP-4 inhibition. Blood glucose and insulin were frequently sampled. DPP-4 inhibitor was given at -20 min, the incretin at -5 min and the intravenous glucose tolerance test (0.4 g glucose/kg) commenced at 0 min. G-AUC and I-AUC, insulinogenic index and glucose efflux, were calculated from glucose and insulin curves. Systemic DPP-4 inhibition potentiated the acute GIP incretin effects: I-AUC (115±34 vs. 153±39 ng·min/ml), increased the insulinogenic index (0.74±0.24 vs. 0.99±0.26 ng/mmol), and improved glucose efflux (19.8±3.1 vs. 20.5±5.0 min-1). The GLP-1 incretin effects were diminished: I-AUC (124±18 vs. 106±38 ng·min/ml), the insulinogenic index was decreased (0.70±0.18 vs. 0.50±0.19 ng/mmol), and glucose efflux declined (14.9±3.1 vs. 11.1±3.7 min-1). GLP-1 and GIP differ remarkably in their glucoregulatory actions in healthy rats when DPP-4 is inhibited. These previously unrecognized actions of DPP-4 inhibitors could have implications for future use in humans.
Laboratory testing for the antiphospholipid syndrome: making sense of antiphospholipid antibody assays
Authors: Favaloro Emmanuel J. , Wong Richard C.W. 
Published: January 2011

AbstractThe antiphospholipid syndrome (APS) is an autoimmune condition characterised by a wide range of clinical features (primarily thrombosis and/or obstetric related), associated with the presence of antiphospholipid antibodies (aPL) as detected by a diverse range of laboratory tests. APS remains a significant diagnostic challenge for clinicians across a wide range of specialities, largely due to issues related to laboratory testing as well as the expanding range of reported clinical manifestations of APS. The laboratory issues include limitations in detailed knowledge by both clinical and laboratory personnel regarding the ‘complete’ range of available aPL tests, as well as ongoing problems with assay reproducibility and standardisation. aPL are identified using diverse laboratory procedures based on one of two distinct test processes, namely solid phase and liquid phase assays. The former includes anticardiolipin antibodies (aCL) and anti-β2-glycoprotein I antibodies (aβ2GPI). The latter are centred on clot-based tests that are used to identify the so-called lupus anticoagulant (LA). This article will discuss: (i) issues related to laboratory testing for APS in terms of the currently available solid-phase and liquid-phase assays, and identifiable biases resulting from these tests usually being performed in different laboratories; (ii) current problems with calibration, standardisation and reproducibility of these assays; (iii) pre-analytical, analytical and post-analytical considerations and ongoing initiatives for improvement; (iv) issues related to potential combinations/panels of available aPL tests; and (v) the entities of seropositive APS, seronegative APS and non-APS aPL-positivity. In doing so, this review will hopefully help bridge the two disciplines of haematology and immunology (‘representing’ liquid-phase and solid-phase aPL testing, respectively), by improving the understanding of those working in each of these disciplines of the merits and limitations of the assays performed in the other discipline, and encouraging inter-discipline cooperation in the reporting of aPL test results.
Evaluation of hematological parameters on admission for the prediction of 7-day in-hospital mortality in a large trauma cohort
Authors: Lam Siu W. , Leenen Luke P.H. , van Solinge Wouter W. , Hietbrink Falco , Huisman Albert 
Published: January 2011

AbstractBackground:We evaluated the complete blood count (CBC) for the prediction of 7-day in-hospital mortality in a large adult trauma cohort.Methods:We conducted an analysis of two prospectively collected databases on 1673 patients aged ≥18 years admitted to a level I trauma center (2005–2007). Comparisons between survivors and non-survivors within 7 days after admission and between single and multiple trauma patients were made. Discriminative performance for 7-day in-hospital mortality was assessed using the area under the receiver operating characteristic curve (ROC). Logistic regression was used to identify independent prognostic factors for 7-day in-hospital mortality.Results:Comparison between survivors and non-survivors showed significant differences in white blood cell (WBC) count, absolute neutrophil count, segmented neutrophil count and most red blood cell (RBC) and platelet indices. Comparison between single and multiple trauma patients showed significant differences for WBC count and differential count and most RBC and platelet indices. Among the CBC parameters, RBC count (ROC=0.748), hemoglobin concentration (Hb) (ROC=0.734), hematocrit (Ht) (ROC=0.726), platelet count (PLT) (ROC=0.684) and plateletcrit (PCT) (ROC=0.696) showed the highest ROC. Using logistic regression we showed that RBC count, Hb, Ht, PLT and PCT were predictors of 7-day in-hospital mortality independently of patient's age, injury severity and initial physiological state.Conclusions:Significant differences in CBC parameters were found between survivors and non-survivors and between patients with single and multiple trauma, but most of the CBC parameters demonstrated poor to moderate pre dictive ability for 7-day in-hospital mortality in adult trauma patients. Routine laboratory workup of trauma patients should be performed as treatment guidance. However, prognostic value of initial hematological parameters remains limited.
Advanced glycation endproducts as gerontotoxins and biomarkers for carbonyl-based degenerative processes in Alzheimer's disease
Authors: Rahmadi Anton , Steiner Nicole , Münch Gerald 
Published: January 2011

Abstract
Alzheimer's disease (AD) is the most common dementia disorder of later life. Although there might be various different triggering events in the early stages of the disease, they appear to converge on a few characteristic final pathways in the late stages, characterized by inflammation and neurodegeneration. Here, we review the hypothesis that advanced glycation end products (AGEs), which reflect carbonyl stress, an imbalance between the production of reactive carbonyl compounds and their detoxification, can serve as biomarkers for the progression of disorder. AGE modification may explain many of the neuropathological and biochemical features of AD, such as extensive protein cross-linking shown as amyloid plaques and neurofibrillary tangles, inflammation, oxidative stress and neuronal cell death. Although accumulation of AGEs is a normal feature of aging, it appears to be significantly accelerated in AD. We suggest that higher AGE concentrations in brain tissue and in cerebrospinal fluid might be able to distinguish between normal aging and AD.
Elevated concentrations of Nɛ-homocysteinyl-lysine isopeptide in acute myocardial infarction: links with ADMA formation
Authors: Zaąbczyk Michał , Głowacki Rafał , Machnik Andrzej , Heród Paweł , Kazek Grzegorz , Jakubowski Hieronim , Undas Anetta 
Published: January 2011

Abstract

Background: A homocysteine (Hcy) metabolite, thioester Hcy-thiolactone, whose reaction with protein lysine residues affords N-homocysteinylated proteins, has been implicated in cardiovascular disease. Proteolytic turnover of N-homocysteinylated proteins generates the isopeptide Nɛ-homocysteinyl-lysine (N-Hcy-Lys).

Methods: We determined N-Hcy-Lys in serum and a NO syntase inhibitor asymmetric dimethylarginine (ADMA), as well as symmetric dimethylarginine (SDMA) and glutathione in plasma by high performance liquid chromatography in 52 consecutive patients with acute myocardial infarction (AMI) recruited within the first 12 h following onset of chest pain. Associations of N-Hcy-Lys with markers of thrombin generation, oxidative stress, enhanced inflammation, fibrinolysis, and autoantibodies against homocysteinylated proteins were also analyzed.

Results: N-Hcy-Lys concentrations, detectable in 45 (86.5%) patients (>0.1 μmol/L), were 127.3% higher compared with healthy controls. N-Hcy-Lys correlated with ADMA (r=0.50; p<0.001), SDMA (r=0.43; p<0.01), glutathione (r=0.37; p<0.05), fibrinogen (r=0.39; p<0.01) and plasminogen activator inhibitor-1 (r=0.32; p<0.05), but not with plasma total Hcy, anti-N-Hcy-protein autoantibodies, vitamin B12, folate, interleukin-6, plasma thrombin-antithrombin (TAT) complexes, prothrombin fragments F1+2 or 8-isoprostaglandin F2α a marker of oxidative stress.

Conclusions: N-Hcy-Lys is increased in AMI patients and its formation is linked with the nitric oxide synthase inhibitor ADMA.
Trefoil factor family peptides in human saliva and cyclical cervical mucus. Method evaluation and results on healthy individuals
Authors: Samson Mie Hessellund , Chaiyarit Ponlatham , Nortvig Helene , Vestergaard Else Marie , Ernst Erik , Nexo Ebba 
Published: January 2011

Abstract

Background: Trefoil peptides are 7–12 kDa molecules, se-creted by a variety of mucin-producing epithelial cells from different tissues and believed to be essential for protection and maintenance of gastrointestinal mucosa. Data on concentrations of trefoil peptides in secretions are limited.

Methods: We validated in-house ELISA assays, developed for measurement of trefoil peptide concentrations (TFF1, TFF2 and TFF3) in serum, for use with saliva and cervical mucus. Saliva from healthy individuals (n=30), and cervical mucus as well as blood collected three times during the menstrual cycle from healthy women (n=18) were analyzed.

Results: Recovery of all trefoil peptides in the initial supernatants of saliva and (cervical mucus) were 86 and (92)% or more. Recovery of exogenously added trefoil peptides was 93 and (95)% or more. Western blotting showed that antibodies used in the TFF3-ELISA assay recognised one molecule of the same size as TFF3 in both saliva and cervical mucus. Median concentrations of TFF1, TFF2 and TFF3 in saliva and (cervical mucus) were 2.7 (2.7), 0.08 (0.58) and 14 (430) nmol/g protein, with a significant decrease in concentrations in cervical mucus after ovulation. Serum concentrations resembled previously measured values in blood donors and showed no cyclic change.

Conclusions: Previously established ELISA assays can be employed for measurement of trefoil peptides in saliva and cervical mucus. TFF3 was the predominant trefoil peptide in both saliva and cervical mucus, and TFF3 in cervical mucus represents the highest concentration measured in a biological fluid to date.