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Accurate elemental quantification of materials by X-ray detection techniques in electron microscopes or microprobes can only be carried out if the appropriate mass absorption coefficients (MACs) are known. With continuous advancements in experimental techniques, databases of MACs must be expanded in order to account for new detection limits. Soft X-ray emission spectroscopy (SXES) is a characterization technique that can detect emitted X-rays whose energies are in the range of 10 eV to 2 keV by using a varied-line-spaced grating. Transitions producing soft X-rays can be detected and accurate MACs are required for use in quantification. This work uses Monte Carlo modeling coupled with multivoltage SXES measurements in an electron probe micro-analyzer (EPMA) to compute MACs for the L2,3-M and Li Kα transitions in a variety of aluminum alloys. Electron depth distribution curves obtained by the software MC X-ray are used in a parametrized fitting equation. The MACs are calculated using a least-squares regression analysis. It is shown that X-ray distribution cross-sections at such low energies need to take into account additional contributions, such as Coster–Kronig transitions, Auger yields, and wave function effects in order to be accurate.
Alluvial mineral sands rank among the most complex subjects for mineral characterization due to the diverse range of minerals present in the sediments, which may collectively contain a daunting number of elements (>20) in major or minor concentrations (>1 wt%). To comprehensively characterize the phase abundance and chemistry of these complex mineral specimens, a method was developed using hyperspectral x-ray and cathodoluminescence mapping in an electron probe microanalyser (EPMA), coupled with automated cluster analysis and quantitative analysis of clustered x-ray spectra. This method proved successful in identifying and quantifying over 40 phases from mineral sand specimens, including unexpected phases with low modal abundance (<0.1%). The standard-based quantification method measured compositions in agreement with expected stoichiometry, with elemental detection limits in the range of <10–1,000 ppm, depending on phase abundance, and proved reliable even for challenging mineral species, such as the multi-rare earth element (REE) bearing mineral xenotime [(Y,REE)PO4] for which 24 elements were analyzed, including 12 overlapped REEs. The mineral identification procedure was also capable of characterizing mineral groups that exhibit significant compositional variability due to the substitution of multiple elements, such as garnets (Mg, Ca, Fe, Mn, Cr), pyroxenes (Mg, Ca, Fe), and amphiboles (Na, Mg, Ca, Fe, Al).
Hyperspectral soft X-ray emission (SXE) and cathodoluminescence (CL) spectrometry have been used to investigate a carbonaceous-rich geological deposit to understand the crystallinity and morphology of the carbon and the associated quartz. Panchromatic CL maps show both the growth of the quartz and the evidence of recrystallization. A fitted CL map reveals the distribution of Ti4+ within the grains and shows subtle growth zoning, together with radiation halos from 238U decay. The sensitivity of the SXE spectrometer to carbon, together with the anisotropic X-ray emission from highly orientated pyrolytic graphite, has enabled the C Kα peak shape to be used to measure the crystal orientation of individual graphite regions. Mapping has revealed that most grains are predominantly of a single orientation, and a number of graphite grains have been investigated to demonstrate the application of this new SXE technique. A peak fitting approach to analyzing the SXE spectra was developed to project the C Kα 2pz and 2p(x+y) orbital components of the graphite. The shape of these two end-member components is comparable to those produced by electron density of states calculations. The angular sensitivity of the SXE spectrometer has been shown to be comparable to that of electron backscatter diffraction.
Carbonate glasses can be formed routinely in the system K2CO3–MgCO3. The enthalpy of formation for one such 0.55K2CO3–0.45MgCO3 glass was determined at 298 K to be 115.00 ± 1.21 kJ/mol by drop solution calorimetry in molten sodium molybdate (3Na2O·MoO3) at 975 K. The corresponding heat of formation from oxides at 298 K was −261.12 ± 3.02 kJ/mol. This ternary glass is shown to be slightly metastable with respect to binary crystalline components (K2CO3 and MgCO3) and may be further stabilized by entropy terms arising from cation disorder and carbonate group distortions. This high degree of disorder is confirmed by 13C MAS NMR measurement of the average chemical shift tensor values, which show asymmetry of the carbonate anion to be significantly larger than previously reported values. Molecular dynamics simulations show that the structure of this carbonate glass reflects the strong interaction between the oxygen atoms in distorted carbonate anions and potassium cations.
An improved understanding of diagnostic and treatment practices for patients with rare primary mitochondrial disorders can support benchmarking against guidelines and establish priorities for evaluative research. We aimed to describe physician care for patients with mitochondrial diseases in Canada, including variation in care.
We conducted a cross-sectional survey of Canadian physicians involved in the diagnosis and/or ongoing care of patients with mitochondrial diseases. We used snowball sampling to identify potentially eligible participants, who were contacted by mail up to five times and invited to complete a questionnaire by mail or internet. The questionnaire addressed: personal experience in providing care for mitochondrial disorders; diagnostic and treatment practices; challenges in accessing tests or treatments; and views regarding research priorities.
We received 58 survey responses (52% response rate). Most respondents (83%) reported spending 20% or less of their clinical practice time caring for patients with mitochondrial disorders. We identified important variation in diagnostic care, although assessments frequently reported as diagnostically helpful (e.g., brain magnetic resonance imaging, MRI/MR spectroscopy) were also recommended in published guidelines. Approximately half (49%) of participants would recommend “mitochondrial cocktails” for all or most patients, but we identified variation in responses regarding specific vitamins and cofactors. A majority of physicians recommended studies on the development of effective therapies as the top research priority.
While Canadian physicians’ views about diagnostic care and disease management are aligned with published recommendations, important variations in care reflect persistent areas of uncertainty and a need for empirical evidence to support and update standard protocols.
Electron and proton microprobes, along with electron backscatter diffraction (EBSD) analysis were used to study the microstructure of the contemporary Al–Cu–Li alloy AA2099-T8. In electron probe microanalysis, wavelength and energy dispersive X-ray spectrometry were used in parallel with soft X-ray emission spectroscopy (SXES) to characterize the microstructure of AA2099-T8. The electron microprobe was able to identify five unique compositions for constituent intermetallic (IM) particles containing combinations of Al, Cu, Fe, Mn, and Zn. A sixth IM type was found to be rich in Ti and B (suggesting TiB2), and a seventh IM type contained Si. EBSD patterns for the five constituent IM particles containing Al, Cu, Fe, Mn, and Zn indicated that they were isomorphous with four phases in the 2xxx series aluminium alloys including Al6(Fe, Mn), Al13(Fe, Mn)4 (two slightly different compositions), Al37Cu2Fe12 and Al7Cu2Fe. SXES revealed that Li was present in some constituent IM particles. Al SXES mapping revealed an Al-enriched (i.e., Cu, Li-depleted) zone in the grain boundary network. From the EBSD analysis, the kernel average misorientation map showed higher levels of localized misorientation in this region, suggesting greater deformation or stored energy. Proton-induced X-ray emission revealed banding of the TiB2 IM particles and Cu inter-band enrichment.
Mesoporous silicas were synthesized via a surfactant-templated sol-gel route using castor oil as the templating agent under acidic medium. The resulting silicas were subsequently amine functionalized with 3-aminopropyltriethoxysilane (NH2-MTS), [3-(2-aminoethylamino)-propyl]trimethoxysilane (NN-MTS), and [3-(diethylamino)propyl]trimethoxysilane(DN-MTS) to introduce surface basicity. Surface physicochemical properties were characterized by field emission gun scanning electron microscopy (FEGSEM), nitrogen porosimetry, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). As-synthesised materials exhibit type IV adsorption-desorption isotherms characteristic of mesoporous structures. Clusters of spherical shaped materials were observed by FEGSEM, suggesting growth of silica occurs within colloidal dispersions. High-resolution N 1s XP spectra and DRIFT spectra confirmed the presence of amine groups in the organo-amine functionalised mesoporous silicas. The amine functionalised mesoporous silicas were active for the transesterification of tributyrin with methanol, with conversion found to increase from NH2-MTS< NN-MTS< DN-MTS.
Social preferences and third-party enforcement of formal contracts are two mechanisms that facilitate performance of an agreement. The standard argument is that formal, enforceable contracts substitute when the social preferences of trust and trustworthiness are lacking. We explore the alternative hypothesis that trust and contract enforcement are complements. We measure social preferences from both a Trust Game and a social values survey, using them as explanatory variables in a Contract Game. We find that both increased contract enforcement and high trusting preferences lead to enhanced rates of contract formation and larger investments. There is an important interaction effect, where trusting individuals enter into agreements at a greater rate and make larger investments when enforcement is greater. Thus, contracts and trust complement one another.
Children with cancer are potentially at a high risk of plasma 25-hydroxyvitamin D (25(OH)D) inadequacy, and despite UK vitamin D supplementation guidelines their implementation remains inconsistent. Thus, we aimed to investigate 25(OH)D concentration and factors contributing to 25(OH)D inadequacy in paediatric cancer patients. A prospective cohort study of Scottish children aged <18 years diagnosed with, and treated for, cancer (patients) between August 2010 and January 2014 was performed, with control data from Scottish healthy children (controls). Clinical and nutritional data were collected at defined periods up to 24 months. 25(OH)D status was defined by the Royal College of Paediatrics and Child Health as inadequacy (<50 nmol/l: deficiency (<25 nmol/l), insufficiency (25–50 nmol/l)), sufficiency (51–75 nmol/l) and optimal (>75 nmol/l). In all, eighty-two patients (median age 3·9, interquartile ranges (IQR) 1·9–8·8; 56 % males) and thirty-five controls (median age 6·2, IQR 4·8–9·1; 49 % males) were recruited. 25(OH)D inadequacy was highly prevalent in the controls (63 %; 22/35) and in the patients (64 %; 42/65) at both baseline and during treatment (33–50 %). Non-supplemented children had the highest prevalence of 25(OH)D inadequacy at every stage with 25(OH)D median ranging from 32·0 (IQR 21·0–46·5) to 45·0 (28·0–64·5) nmol/l. Older age at baseline (R −0·46; P<0·001), overnutrition (BMI≥85th centile) at 3 months (P=0·005; relative risk=3·1) and not being supplemented at 6 months (P=0·04; relative risk=4·3) may have contributed to lower plasma 25(OH)D. Paediatric cancer patients are not at a higher risk of 25(OH)D inadequacy than healthy children at diagnosis; however, prevalence of 25(OH)D inadequacy is still high and non-supplemented children have a higher risk. Appropriate monitoring and therapeutic supplementation should be implemented.
Recent studies point to overlap between neuropsychiatric disorders in symptomatology and genetic aetiology.
To systematically investigate genomics overlap between childhood and adult attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and major depressive disorder (MDD).
Analysis of whole-genome blood gene expression and genetic risk scores of 318 individuals. Participants included individuals affected with adult ADHD (n = 93), childhood ADHD (n = 17), MDD (n = 63), ASD (n = 51), childhood dual diagnosis of ADHD–ASD (n = 16) and healthy controls (n = 78).
Weighted gene co-expression analysis results reveal disorder-specific signatures for childhood ADHD and MDD, and also highlight two immune-related gene co-expression modules correlating inversely with MDD and adult ADHD disease status. We find no significant relationship between polygenic risk scores and gene expression signatures.
Our results reveal disorder overlap and specificity at the genetic and gene expression level. They suggest new pathways contributing to distinct pathophysiology in psychiatric disorders and shed light on potential shared genomic risk factors.
Quality of life (QOL) is lower in older adults with generalized anxiety disorder (GAD). QOL generally improves following cognitive-behavioral treatment for GAD. Little is known, however, about additional variables predicting changes in QOL in older adults with GAD. This study examined predictors of change in QOL among older participants in a randomized clinical trial of cognitive behavioral therapy (CBT) for GAD, relative to enhanced usual care (EUC).
Hierarchical multilevel mixed-model analyses were used to examine inter-individual and intra-individual factors that predicted QOL over time. Predictors were categorized into treatment, personal and clinical characteristics.
QOL improved over time, and there was significant variability between participants in change in QOL. Controlling for treatment condition, baseline general self-efficacy, baseline social support, within-person variation in worry and depression and average levels of depression across different time points predicted changes in QOL.
QOL has increasingly been used as an outcome measure in treatment outcome studies to focus on overall improvement in functioning. Attention to improvement in symptoms of depression and worry, along with psychosocial variables, such as social support and self-efficacy, may help improve QOL in older adults with GAD.
This study was a secondary study of data from a randomized clinical trial (NCT00308724) registered with clinical.trials.gov.
We generalize and improve recent results by Bóna and Knopfmacher and by Banderier and Hitcz-enko concerning the joint distribution of the sum and number of parts in tuples of restricted compositions. Specifically, we generalize the problem to general combinatorial classes and relax the requirement that the sizes of the compositions be equal. We extend the main explicit results to enumeration problems whose counting sequences are Riordan arrays. In this framework, we give an alternative method for computing asymptotics in the supercritical case, which avoids explicit diagonal extraction.
Part III returns to the problem at the heart of this book, namely how to make judicious choices of contours of integration to asymptotically evaluate the Cauchy integral (1.3.1). This may be summarized in one sentence as: push the chain of integration down to a critical point, then interpret the integral locally as an instance of a type i.e. classically understood. Depending on the geometry near the critical point, this step may take one of several forms. Each of the three chapters following this one details the process from start to finish in one of three cases, which together cover most known examples of rational generating functions. Extensions beyond this class are discussed briefly in Chapter 13.
These three chapters are self-contained, developing the theory in full rigor for the respective three cases. The present chapter is a complement, in which motivation and intuition are given for all the development in subsequent chapters. Its mission is to expand the six steps given at the end of Section 1.3 into a comprehensible program. In some cases we give heuristics without proof or give proofs that rely on Morse theory (included in Appendixes B and C). In one case, the heuristic relies on a conjecture not yet solved. Nevertheless, these heuristics provide firm guidance regarding how to accomplish the ensuing analyses. When these methods are fully developed in later chapters, only vestiges of the Morse-theoretic infrastructure remain.