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This article discusses a case of infantile neuroaxonal dystrophy (INAD) in a 7-year-old boy. The patient experienced delayed speech and motor development, weakness in his lower limbs, and limited eye contact. Magnetic resonance imaging revealed abnormal signals in the bilateral globus pallidus, iron deposits in the pallid globules, and cerebellar atrophy. INAD is a rare autosomal recessive neurodegenerative disorder that typically presents before the age of 3. The authors of the article are Qinglin Zhong, Qingping Zhong, and Binglin Lai, and the research was conducted at the Department of Medical Imaging, Ganzhou People's Hospital in China. [Extracted from the article]

The patients in this manuscript have given written informed consent to publication of their case details. Self-reported allergic rhinitis and/or allergic conjunctivitis associate with IL13 rs20541 polymorphism in finnish adult asthma patients. [Extracted from the article]

Examines the electron transport characteristics of ZnS. Application of the Boltzmann transport equation in determining the transport characteristics of the zinc compound; Information on the treatment of electron scattering in ZnS; Evaluation of the transport measurement results on ZnS.

The characteristics of Acid Blue 74 (AB74), Alizarin Red S (ARS), Acid Orange 7 (AO7) and Direct Red 28 (DR28) were investigated by using EEM fluorescence spectroscopy and UV-vis spectroscopy. The results suggest that the azo and anthraquinone dyes can be quickly distinguished from other dyes (such as AB74) according to their different total fluorescence intensity. During the decolorization process by the electro-Fenton technique, the total fluorescence intensity of the four dyes all would increase to their maximum value, but the fluorescence intensity increase in multiples of 12 (ARS), 61 (AO7), and 13 (DR28) times was much higher than that of AB74 (3 times). Furthermore, the different fluorescence intensities of the four dyes in the electro-Fenton process resulted mainly from their different chemical structure characteristics. Additionally, EEM spectroscopy can support much more information about the chemical structure characteristics of the dyes than the conventional UV-vis spectroscopy. [ABSTRACT FROM AUTHOR]

This paper employs the higher-order method of moments (MoM) based adaptive integral method (AIM) to analyze Non-Uniform Rational B-Spline (NURBS) surfaces modeled 3D PEC problem. It employs a quadrature points based projection procedure, in which the basis functions can be expanded with much fewer Dirac delta functions defined on the grid nodes than the commonly used AIM. Meanwhile, the Gaussian interpolation formula is introduced to enlarge the grid space which can also improve the efficiency of the proposed method. Accordingly, the new method can deal with electrically large problems properly, due to the accuracy of the NURBS surfaces in geometry modeling and the efficiency of higher-order AIM in computational and memory costs. Numerical results show the validity of the new method. [ABSTRACT FROM AUTHOR]

Ultraviolet and visible upconversion emissions in Tb3+/Yb3+ co-doped YF3–BaF2–Ba(PO3)2 glasses were observed under 980-nm laser diode excitation. The dependence of the emission intensities of Tb3+ on the pump power reveals that two-photon processes account for blue cooperative emission of Yb3+ at 476 nm and green upconversion emission of Tb3+ at 543 nm, and three-photon processes for ultraviolet emission of Tb3+ in the wavelength range of 379–435 nm. The effects of Tb3+ concentration on the emission intensity and the lifetime of Tb3+ and Yb3+ are investigated in detail. It is found that the cooperative energy transfer from a pair of excited Yb3+ ions to a ground Tb3+ ion is responsible for the appearance of blue and green upconversion emissions due to the 5D4→7F J ( J=6,5,4,3) transitions of Tb3+, and the resonance energy transfer from Yb3+ to Tb3+ accounts for the population on the 5D3,5G6 level and ultraviolet upconversion emission. [ABSTRACT FROM AUTHOR]

Highlights the workshop concerning the biological applications of x-ray microbeams. Features of x-ray microbeams; Environmental and nanobiotechnological uses of x-ray microscopy; Benefits provided by x-ray microprobes.

Fabricates and characterizes a linear and circular zone plate with a blazed zone profile using synchrotron x rays. Improved performance in compared with a zone plate with a square profile; Experimental characterization; Special applications.

Examines nanometer focusing of hard x-rays by phase zone plates (PZP). Numerical aperture of the PZP; Flux density gain at first-order focus; Fabrication of the PZP; Experimental characterization.

A tapered undulator, in which the entrance and exit magnetic gaps are different, will show an increase in the energy width of the harmonics compared to the nontapered case. This increase can occur without substantial broadening in the collimation of the undulator radiation. We present the spectral properties measured for a tapered 3.3-cm period prototype undulator of the Advanced Photon Source at the Cornell High Energy Synchrotron Source. The width of the on-axis first harmonic at 6.9 keV increased from 0.32 to 0.66 keV for a gap tapering of 12%. Minimal angular broadening in the first harmonic x rays was detected and measurements of off-axis radiation were also performed. The results are found to be in good agreement with model calculations. [ABSTRACT FROM AUTHOR]

Reports on the workshop on the biological applications of X-ray microscopy and imaging held at Argonne National Laboratory in Argonne, Illinois. Duration of the workshop; Speakers of the workshop; Topics discussed by speakers.

Spectroscopic ellipsometry (SE) was used to characterize the sol-gel derived (K[sub 0.5]Na[sub 0.5])[sub 0.4](Sr[sub 0.6]Ba[sub 0.4])[sub 0.8]Nb[sub 2]O[sub 6] (KNSBN) thin films as a function of sol concentration. In the analysis of the measured SE spectra, a modified double-layer Forouhi-Bloomer model was adopted to represent the optical properties of the KNSBN films. In this model, the films were assumed to consist of two layers--a bottom bulk KNSBN layer and a surface layer that composed of bulk KNSBN as well as void. Good agreement was obtained between the measured spectra and the model calculations in the chosen spectral region. Effective medium approximation theory was used to evaluate the effective refractive index for the surface layer. The results of SE have been correlated with atomic force microscopy measurements of surface roughness. Our analyses have shown that the surface layer had a lower refractive index than the bottom one. In addition, the refractive index and the surface roughness of the KNSBN films increase with the sol concentration. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Discusses the coherence based contrast enhancement in x-ray radiography with a photoelectron emission microscope (PEEM). Main requirements to obtain the contrast enhancement; Role of edge-enhanced fringes; Phase effect on the quality of imaging.

Describes a hard x-ray imaging microscope based on a phase zone plate. Optical scheme of the instrument; Resolution measurements; Possible applications of the device.

Presents a fast phase-space measurement technique that was tested during an Advanced Photon Source/Cornell High Energy Synchrotron Source undulator run. Theory of the technique; Use of a Gaussian source to describe a synchrotron-radiation source of finite electron-beam emittance; Vertical phase-space ellipse of the undulator photon beam constructed from experimental data.

Examines the fabrication of Fresnel phase zone plate by x-ray lithographic technique. Derivation of spatial resolution in the micrometer range; Dominance of geometric demagnification of the source; Application of zeroth-order x-ray to the focusing device.

Near saturation, air bubbles and pockets can be trapped in the porous network of soils. The aim of this paper was to present a coupled model that takes into account the effect of this entrapped air on the poro-elasto-plastic behavior of the soil. The model takes into account the physical-mechanical interactions between different phases as well as the kinematics of each constituent (liquid water, dissolved air, gaseous air and solid grains). This new model was implemented in a FEM code. Some numerical simulations were performed to demonstrate its ability to reproduce a continuous transition of unsaturated to saturated states. [ABSTRACT FROM AUTHOR]

We used hard x-ray fluorescence and soft x-ray transmission microscopy to quantitatively measure “in situ” Cu/SiO[sub 2] interconnect dimensions down to 0.3 μm dimensions. We describe methods and analysis techniques for measuring submicron linewidths, lengths, and thicknesses with accuracies of 30–60 nm precision. The dimensions and shape of submicron Cu vias, W lines, and a 20 nm Ta liner and an electromigration defect (void) were determined by these methods. These nondestructive techniques promise to be useful for nanometer precision metrology studies of a variety of materials systems. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Radially oriented Nd-Fe-B ring magnets have been prepared by backward extrusion of melt-spun powder. The position dependent of the microstructure, the magnetic properties, and the crystal alignment of the extruded rings have been investigated. The magnetic properties in radial direction increase slightly along the axis from the bottom to the middle then steeply decrease at the upper end of the ring. The magnetic properties and x-ray diffraction patterns of the upper end are very close to that of the isotropic pressed precursor. It suggests that the extruded ring approximately retains the initial structure at its upper end which is because the formation of texture is difficult at the initial stage of hot extrusion. Characteristic microstructure morphologies were found at different spatial positions: flake-shaped grains for the inner, elongated grains for the middle, and particle-shaped grains for the outer region in the cross section. Only particle-shaped grains were observed at the upper end of the ring. But the circumferential homogeneity of the surface magnetic flux densities is better in an extruded ring magnet than in a radially oriented ring prepared by sintering method. The deformation and texture formation processes were discussed. The deformation and texture formation in backward extruded magnets from melt-spun Nd-Fe-B precursors may possibly involve grain boundary sliding and grain rotation, solution-precipitation process, and preferred growth of Nd2Fe14B nanograins along the easy growth a-axis. [ABSTRACT FROM AUTHOR]

We demonstrate that unmonochromatized synchrotron radiation stimulates the formation of surface-reacted nitride species on silicon at room temperature. The experimental evidence was obtained by exposing a NH3-covered Si(111) surface to synchrotron radiation. This class of phenomena is relevant for the manufacturing technology of submicron electronic devices. [ABSTRACT FROM AUTHOR]

This study investigated micromixers formed by a T-junction and a mixing channel consisting of serial modules formed by appropriately arranging the subsections with right shifted T-shaped, left shifted T-shaped and square cross-sections. The T-shaped cross-sections are constructed by protrusions and indentations on the channel wall. The variation of shape and size of the channel cross-section may induce a strong swirl structure of flow to enhance fluid mixing. Four parameters (the lengths of the three aforementioned subsections and the sequence of modules) were selected to optimize the micromixer, and computational fluid dynamics (CFD) together with Taguchi method was applied to select the values of the parameters. Then, the micromixer was fabricated by a lithography process and the mixing of pure DI water and a solution of Rhodamine B in DI water in the micromixer was observed by using a confocal spectral microscope imaging system. The numerical and experimental results, compared to those of a straight channel with the same hydrodynamic diameter, show that the novel micromixer with the deliberately designed geometry with a hydrodynamic diameter equal to 120 μm enhances fluid mixing efficiently at relatively low Reynolds numbers (0.01-10), corresponding to the mean velocities from 0.000081 to 0.081 m/s. The effects of the four parameters on fluid mixing in the proposed micromixer are examined by CFD simulation. [ABSTRACT FROM AUTHOR]

Hard x-ray microprobes with suboptical resolution have emerged as powerful probes of the elemental constituents of biomedical and environmental specimens. In particular, trace element distributions in the native state of many of these systems can be quantitatively mapped. This has a wide range of applications, particularly in following the metal distribution under changing conditions. If systems such as cells are exposed to known environmental changes, or if the interaction between pathogens and host cells lead to a change of trace metal distribution, important information about the underlying mechanism can be gained. We will present several biomedical and environmental applications of the hard x-ray microprobes at sector 2 of the Advanced Photon Source. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report on extensions that have been implemented in SHADOW, our x-ray and synchrotron sources modeling program. New types of sources have been implemented: (a) undulators are now part of the gallery of sources; (b) an optimization module has been implemented for systems with high losses. For the ray-tracing module, we have now implemented zone plates optical systems. Several new analysis programs have been implemented, as well as a new user's interface. Two modules, PLOTXY and SYSPLOT, in particular, have been extended and improved. PLOTXY can now plot the wave-front surface directly, while SYSPLOT can generate a realistic layout of the optical system. Work is currently in progress on the implementation of asymmetric crystal diffraction and effect of roughness on image formation. [ABSTRACT FROM AUTHOR]

The construction of the MAXIMUM scanning photoelectron microscope has been recently funded. A preliminary description has already been reported. We will present the final construction layout of the system, with particular attention dedicated to the optical components. Briefly, the system is based on a variable line spaced grating monochromator used to filter the radiation emitted by a 30 poles undulator installed at Aladdin. The radiation is then refocussed on a pinhole that is suitably demagnified by a Schwartzschild objective to a spot of less than 0.1 μm. The sample is located at the focus and mechanically rastered. The photoelectrons are energy analyzed by a commercial cylindrical mirror analyzer. The main characteristics of the system will be ( 1 ) high flux, (2) independent energy and spatial resolution, and ( 3 ) independent photon and electron energy resolution. All the components are fully decoupled thus allowing maximum flexibility. Detailed ray-tracing and flux estimates based on our new undulator modelling codes will be presented. [ABSTRACT FROM AUTHOR]

We present a new code capable of realistically modeling the radiation from ideal undulator sources, including explicit electron emittance effects. The code has been developed as part of the SHADOW1 x-ray optics ray-tracing program, in order to predict the performances of undulator-based optical systems. The approach is based on a simplified field distribution that allows an efficient calculation of the electron trajectory and of the radiation field. We show explicitly that the undulator radiation pattern is shift-invariant with respect to the electron’s trajectory angles, so that the emittance effects can be included without recomputing the radiation distribution. Furthermore, the time consuming computation of the undulator emission patterns is decoupled from the Monte Carlo sampling of the wavefront, leading to a very fast code. This is achieved by computing the three-dimensional source probability distribution function and then using an inversion algorithm to generate a random variate according to the source distribution. The physical basis of the code and the algorithm used are discussed in detail and some results presented. [ABSTRACT FROM AUTHOR]

Objective Lepidium meyenii (Maca) has been used for centuries for its fertility-enhancing and aphrodisiac properties. In an Australian study, Maca improved anxiety and depressive scores. The effects of Maca on hormones, lipids, glucose, serum cytokines, blood pressure, menopausal symptoms and general well-being in Chinese postmenopausal women were evaluated. Methods A randomized, double-blind, placebo-controlled, cross-over study was conducted in 29 postmenopausal Hong Kong Chinese women. They received 3.3 g/day of Maca or placebo for 6 weeks each, in either order, over 12 weeks. At baseline, week 6 and week 12, estradiol, follicle stimulating hormone (FSH), sex hormone binding globulin (SHBG), thyroid stimulating hormone (TSH), full lipid profiles, glucose and serum cytokines were measured. The Greene Climacteric, SF-36 Version 2, Women's Health Questionnaire and Utian Quality of Life Scales were used to assess the severity of menopausal symptoms and health-related quality of life. Results There were no differences in estradiol, FSH, TSH, SHBG, glucose, lipid profiles and serum cytokines amongst those who received Maca as compared to the placebo group; however, significant decreases in diastolic blood pressure and depression were apparent after Maca treatment. Conclusions Maca did not exert hormonal or immune biological action in the small cohort of patients studied; however, it appeared to reduce symptoms of depression and improve diastolic blood pressure in Chinese postmenopausal women. Although results are comparable to previous similar published studies in postmenopausal women, there might be a cultural difference among the Chinese postmenopausal women in terms of symptom reporting. [ABSTRACT FROM AUTHOR]

Large area aluminum doped zinc oxide films (ZnO:Al) were prepared at room temperature in a magnetron sputtering system. The optical and electrical properties as well as etching behaviors and surface structures of ZnO:Al films before and after etching and annealing treatments were systematically investigated. It is found that the ZnO:Al films prepared at room temperature without annealing show a low total transmission. The carrier concentration seems to be inhomogeneous in the films and increases along the growth direction, which can be derived from the shift of plasma resonance wavelength of the etched ZnO:Al films. The annealing treatment leads to a recrystallization of the ZnO:Al films and a further increase in carrier concentration. Excess annealing treatment would lead to an increase in resistivity. The etching of annealed ZnO:Al films results in different surface structures varying from hill-like to small crater-like shapes with the increasing annealing treatment duration in this case. [ABSTRACT FROM AUTHOR]

Methods to modify the magnetic coercivity and exchange bias field of nanocrystalline antiferromagnetic/ferromagnetic \NiO/\Ni80{\Fe}20 thin films were investigated for bilayers grown using ion-assisted deposition onto different single crystalline substrates. An enhanced coercivity was found at 298 K for the films deposited on single crystalline MgO (100) and \Al_2 \O_3 (11-20) substrates. After field cooling the films to 50 K, the NiO/NiFe bilayer grown on \Al_2 \O_3 (11-20) exhibited the largest exchange bias (\- 25~\Oe). The second part of the study investigated ion-beam modification of the ferromagnetic surface prior to the deposition of the NiO layer. A range of ion-beam bombardment energies (VEH) were used to modify in situ the NiFe surface during the deposition of \NiO/\NiFe/\SiO_2 films. Cross-sectional transmission electron microscopy showed a systematic reduction in the thickness of the NiFe layers with increasing \Ar^ + bombardment energies attributed to etching of the surface. In addition, the bombardment procedure modified the magnetic exchange bias of the composite structure in both the as-prepared and field-cooled state. [ABSTRACT FROM PUBLISHER]

The chemical factors influencing iron solubility (soluble iron/total iron) were investigated in source emission (e.g., biomass burning, coal fly ash, mineral dust, and mobile exhaust) and ambient (Atlanta, GA) fine particles (PM2.5). Chemical properties (speciation and mixing state) of iron-containing particles were characterized using X-ray absorption near edge structure (XANES) spectroscopy and micro-X-ray fluorescence measurements. Bulk iron solubility (soluble iron/total iron) of the samples was quantified by leaching experiments. Major differences were observed in iron solubility in source emission samples, ranging from low solubility (<1%, mineral dust and coal fly ash) up to 75% (mobile exhaust and biomass burning emissions). Differences in iron solubility did not correspond to silicon content or Fe(II) content. However, source emission and ambient samples with high iron solubility corresponded to the sulfur content observed in single particles. A similar correspondence between bulk iron solubility and bulk sulfate content in a series of Atlanta PM2.5 fine particle samples (N = 358) further supported this trend. In addition, results of linear combination fitting experiments show the presence of iron sulfates in several high iron solubility source emission and ambient PM2.5 samples. These results suggest that the sulfate content (related to the presence of iron sulfates and/or acid-processing mechanisms by H2SO4) of iron-containing particles is an important proxy for iron solubility. [ABSTRACT FROM AUTHOR]

Psychological stress is known to activate the hypothalamic–pituitary–adrenal axis, resulting in the release of cortisol from the adrenal cortex into the bloodstream. Cortisol is the major human stress hormone and its health correlates continue to be investigated by laboratories around the world. One line of research suggests that specific situational variables play a role in the creation of a stressful situation. The current study examined the effects of systematically varying several situational characteristics on the cortisol stress response in 80 healthy young women exposed to a public speaking task. Three main factors and its interactions were investigated by locating the expert panel either inside or outside of the room, having the subjects speak either about themselves or somebody else, and by asking half of the subjects to perform a distractor task in addition to performing the public speaking. We interpreted these manipulations as variations of social evaluative threat, ego-involvement, and divided attention. We hypothesized that the variations and their interactions would cause differences in endocrine stress responses. The results showed that only the manipulation of social-evaluative threat had a significant main effect on the cortisol stress response in women. There was a further trend (p = 0.07) for a four-way interaction effect. No other main or interaction effects could be observed. We conclude that in women, social-evaluative threat affects the endocrine stress response. This is in contrast to a previous study showing no effects of this variation in men. Thus, future studies should more closely investigate sex or gender effects that might be interacting with the situational aspects of a stressful task. [ABSTRACT FROM AUTHOR]

Abstract: There is increasing evidence indicating that estrogen replacement therapy produces neuroprotective actions but has undesirable side effects on the reproductive system. Raloxifene is a selective estrogen receptor modulator that exerts estrogen agonist action in the brain while acting as an estrogen antagonist in the reproductive system. In the present study, we investigated whether raloxifene affected the glutamate-induced calcium (Ca2+) overload in rat cultured cortical neurons. The bulk cytosolic intracellular Ca2+ level was measured by using confocal microscopy with fluorescent Ca2+ probe fluo3. Whole-cell recording technique was used to observe the effects of raloxifene on N-methyl-d-aspartate (NMDA)-evoked and voltage-activated Ca2+ currents in cultured cortical neurons. Pre-exposure of cortical neurons to raloxifene (0.5μM–10μM) for 3 min attenuated intracellular Ca2+ increase induced by application of glutamate (300μM) for 1 min. The action of raloxifene was reversible after washout. ICI 182,780 and thapsigargin did not block the action of raloxifene. In whole-cell recording experiments, raloxifene (10μM) significantly reduced the amplitude of the high-voltage-activated Ca2+ current but had no effect on NMDA-evoked Ca2+ current. The present study demonstrates that raloxifene acutely reduces glutamate-induced intracellular Ca2+ increase probably via inhibition of high-voltage-activated calcium channels. [Copyright &y& Elsevier]

Phase-contrast X-ray diffraction imaging and high-angular- resolution diffraction combined with phase-contrast radio- graphic imaging were employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in the symmetric Laue case. The lull-width at hall-maximum (FWHM) of a 440 rocking curve measured from the original crystal was ∼16.7 arcsec and imperfections including line defects. inclusions and other microdefects were observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the 〈1 1 0〉 growth front and have been found to originate mostly in a central growth area and occasionally in outer growth regions. Inclusions of impurities or formations of foreign particles in the central growth region arc resolved in the images with high sensitivity to defects. Slow dehydration led to the broadening of a fairly symmetric 4 4 0 rocking curve by a factor of ∼2.6. which was primarily attributed to (lie dehydration-induced microscopic effects that arc clearly shown in X-ray diffraction images. The details of the observed defects and the significant change in the revealed micro- structures with drying provide insight into the nature of imperfections, nucleation and growth. and the properties of protein crystals. [ABSTRACT FROM AUTHOR]

The bulk minority-carrier lifetime in p- and n-type kerfless epitaxial (epi) crystalline silicon wafers is shown to increase >500x during phosphorus gettering. We employ kinetic defect simulations and microstructural characterization techniques to elucidate the root cause of this exceptional gettering response. Simulations and deep-level transient spectroscopy (DLTS) indicate that a high concentration of point defects (likely Pt) is "locked in" during fast (60 °C/min) cooling during epi wafer growth. The fine dispersion of moderately fast-diffusing recombination-active point defects limits as-grown lifetime but can also be removed during gettering, confirmed by DLTS measurements. Synchrotron-based X-ray fluorescence microscopy indicates metal agglomerates at structural defects, yet the structural defect density is sufficiently low to enable high lifetimes. Consequently, after phosphorus diffusion gettering, epi silicon exhibits a higher lifetime than materials with similar bulk impurity contents but higher densities of structural defects, including multicrystalline ingot and ribbon silicon materials. Device simulations suggest a solar-cell efficiency potential of this material >23%. [ABSTRACT FROM AUTHOR]

Dislocation clusters in multicrystalline silicon limit solar cell performance by decreasing minority carrier diffusion length. Studies have shown that the recombination strength of dislocation clusters can vary by up to two orders of magnitude, even within the same wafer. In this contribution, we combine a surface-analysis approach with bulk characterization techniques to explore the underlying root cause of variations in recombination strength among different clusters. We observe that dislocation clusters with higher recombination strength consist of dislocations with a larger variation of line vector, correlated with a higher degree of variation in dislocation etch-pit shapes (ellipticities). Conversely, dislocation clusters exhibiting the lowest recombination strength contain mostly dislocations with identical line vectors, resulting in very similar etch-pit shapes. The disorder of dislocation line vector in high-recombination clusters appears to be correlated with impurity decoration, possibly the cause of the enhanced recombination activity. Based on our observations, we conclude that the relative recombination activity of different dislocation clusters in the device may be predicted via an optical inspection of the distribution and shape variation of dislocation etch pits in the as-grown wafer. [ABSTRACT FROM AUTHOR]

Coherent hard x-ray beams with a flux exceeding 10[sup 9] photons/sec with a bandwidth of 0.1% will be provided by undulators at the third-generation synchrotron radiation sources such as APS, ESRF, and Spring-8. The availability of such high flux coherent x-ray beams offers excellent opportunities for extending the coherence-based techniques developed in the visible and soft x-ray part of the electromagnetic spectrum to the hard x-ray region. These x-ray techniques (e.g., diffraction-limited microfocusing, holography, interferometry, phase contrast imaging, and signal enhancement) may offer substantial advantages over noncoherence-based x-ray techniques currently used. For example, the signalenhancement technique may be used to enhance an anomalous x-ray or magnetic x-ray scattering signal by several orders of magnitude. Coherent x rays can be focused to a very small (diffraction-limited) spot size, thus allowing construction of high spatial resolution microprobes. This paper will discuss the feasibility of extending some coherence-based techniques to the hard x-ray range and the significant progress that has been made in the development of diffraction-limited focusing optics. Specific experimental results for a transmission Fresnel phase zone plate that can focus 8.2 keV x rays to a spot size of about 2 microns will be briefly discussed. The comparison of measured focusing efficiency of the zone plate with that calculated will be made. Some specific applications of zone plates as coherent x-ray optics will be discussed. [ABSTRACT FROM AUTHOR]

Dislocation clusters in multicrystalline silicon limit solar cell performance by decreasing minority carrier diffusion length. Studies have shown that the recombination strength of dislocation clusters can vary by up to two orders of magnitude, even within the same wafer. In this contribution, we combine a surface-analysis approach with bulk characterization techniques to explore the underlying root cause of variations in recombination strength among different clusters. We observe that dislocation clusters with higher recombination strength consist of dislocations with a larger variation of line vector, correlated with a higher degree of variation in dislocation etch-pit shapes (ellipticities). Conversely, dislocation clusters exhibiting the lowest recombination strength contain mostly dislocations with identical line vectors, resulting in very similar etch-pit shapes. The disorder of dislocation line vector in high-recombination clusters appears to be correlated with impurity decoration, possibly the cause of the enhanced recombination activity. Based on our observations, we conclude that the relative recombination activity of different dislocation clusters in the device may be predicted via an optical inspection of the distribution and shape variation of dislocation etch pits in the as-grown wafer. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the application of standardized ultrasonography in the first trimester. A total of 1670 pregnant women who underwent ultrasonography in the first trimester (1706 fetuses) and 2,562 pregnant women who underwent ultrasonography in the second trimester (2637 fetuses) visiting the Second Affiliated Hospital of Nanchang University from January 2016 to December 2018 were included in this prospective study. Standardized ultrasonography was performed on the fetuses and pregnancy outcomes were tracked in abnormal cases. A total of 20 cases of fetal structural abnormalities were detected in the first trimester and the number of pregnant women who chose to induce labor was as high as 15. A total of 41 cases of fetal soft marker abnormalities were detected in the first trimester and most of these markers returned to normal. A total of 113 cases of malformed fetuses were detected in the second trimester. Additionally, those cases that did not undergo standardized ultrasonography in the first trimester were significantly more likely to show fetal abnormalities in the second trimester than those who had standardized ultrasonography in the first trimester. Some fetal malformations, especially some severe ones, can be detected by standardized ultrasonography in the first trimester. However, standardized ultrasonography in the second trimester which was regard as the best period for fetal malformation detection cannot be replaced by the first trimester. It is better to conduct standardized ultrasonography in both first and second trimesters. [ABSTRACT FROM AUTHOR]

The efficacy of higher-temperature gettering processes in reducing precipitated iron concentrations is assessed by synchrotron-based micro-X-ray fluorescence. By measuring the same grain boundary before and after phosphorus diffusion in a set of wafers from adjacent ingot heights, the reduction in size of individual precipitates is measured as a function of gettering temperature in samples from the top of an ingot intentionally contaminated with iron in the melt. Compared to a baseline 820 °C phosphorus diffusion, 870 °C and 920 °C diffusions result in a larger reduction in iron-silicide precipitate size. Minority carrier lifetimes measured on wafers from the same ingot heights processed with the same treatments show that the greater reduction in precipitated metals is associated with a strong increase in lifetime. In a sample contaminated with both copper and iron in the melt, significant iron gettering and complete dissolution of detectable copper precipitates is observed despite the higher total metal concentration. Finally, a homogenization pre-anneal in N2 at 920 °C followed by an 820 °C phosphorus diffusion produces precipitate size reductions and lifetimes similar to an 870 °C phosphorus diffusion without lowering the emitter sheet resistance. [ABSTRACT FROM AUTHOR]

A hard x-ray Fresnel zone-plate-based microprobe has been designed and integrated into a Newport kappa diffractometer for microdiffraction studies at the 2ID-D beamline at the Advance Photon Source. The microprobe employs 10 and 40 cm (focal length at 8 keV) zone plates to provide high and moderate focusing power, respectively. Each zone-plate assembly has two identical zone plates stacked together to provide higher focusing efficiency for higher energy (30 keV) applications. The mounting base of the microprobe is supported by the side of the base of the diffractometer at one end and the central table of the diffractometer at the other end, thus minimizing the instability of relative positions between the focal spot and the specimen. A x-ray focal spot size smaller than 360 nm and angular repeatability of the sample circles smaller than 0.001° have been demonstrated with this setup. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Strain distributions within a silicon-on-insulator (SOI) layer induced by overlying compressively stressed Si3N4 features were measured using x-ray microbeam diffraction. A comparison of analytical and numerical mechanical models of the depth-averaged strain distributions to the measured strain profiles in the SOI layer indicated a blanket film stress of -2.5 GPa in the Si3N4 features. A two-dimensional boundary element model, implemented to analyze thin film/substrate systems, reproduced the observed strain distributions better than an edge-force formulation due to the incorporation of loading along the Si3N4/Si interface. [ABSTRACT FROM AUTHOR]

Heteroepitaxial thin-film features that are lattice matched to the underlying substrate undergo elastic relaxation at the free edges of the feature. To characterize the degree of elastic relaxation, we employed synchrotron-based x-ray diffraction techniques to map the change in lattice spacing in the thin film at a submicron resolution. Measurements were conducted on 0.24-μm thick, heteroepitaxially grown SiGe strips of various widths on Si (001). A comparison of the SiGe diffraction peak positions across the features provides a real-space mapping of the extent of elastic relaxation as a function of linewidth. The resultant in-plane normal film stress measurements were compared to calculated values from several elastic mechanical models to assess their validity in predicting stress distributions within the features. [ABSTRACT FROM AUTHOR]

The manipulation of strain in micromachined silicon structures presents an opportunity in the control of surface processes in epitaxial growth. With appropriate fabrication techniques, the magnitude, crystallographic direction, and symmetry of the strain at a Si surface can be precisely controlled with this strategy. Synchrotron x-ray microdiffraction techniques allow simultaneous independent measurements of the strain and bending in these structures and serve to calibrate the fabrication process. Bending is the dominant source of strain in a microfabricated Si bridge loaded at its ends by silicon nitride thin films that we have used as a strained substrate in studies of Ge epitaxial growth. The total strain difference between the top and bottom of the bent bridge exceeds 10-3 in present structures and can potentially be increased in optimized devices. These micromachined substrates complement other methods for producing strained silicon and silicon- germanium structures for improved electrical device performance and for fundamental studies of epitaxial growth. [ABSTRACT FROM AUTHOR]

The precipitation and dissolution of copper impurities at oxygen precipitates and stacking faults in silicon were studied using thermal budgets commensurate with standard integrated circuit processing. Additionally, in order to develop a better understanding of the dissolution process, we have obtained results on the chemical state of the copper precipitates. The goal of this work was to determine the feasibility of removing and maintaining copper impurities away from the active device region of an integrated circuit device by use of oxygen precipitates and stacking faults in the bulk of the material. Based on our results, we provide a basis for a predictive understanding of copper precipitation and dissolution in silicon and we discuss the feasibility of copper impurity control in silicon integrated circuit devices. [ABSTRACT FROM AUTHOR]