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X-ray excited Photoelectron Spectroscopy (XPS) has become an indispensable tool for the study of metals and semiconductors. Due to the small mean free path of the photoelectrons In solids of the order of a few nanometers for energies in the keV range, it is a surface analysis technique. Its capability of quantitative analysis of all elements except hydrogen and helium and their chemical bonding states has recently been combined with small area and imaging analysis to typical spatial resolutions of about 10 μm. After a brief survey of the basic capabilities and limitations of XPS, some illustrative examples in typical metals and semiconductor research areas are presented, such as surface contamination and failure analysis in microelectronics, oxidation and corrosion, segregation at surfaces and interfaces, oxide/metal and oxide/semiconductor interfaces, and thin film analysis using angle resolved XPS and sputter depth profiling. Recent developments emphasize improved data evaluation and quantification schemes as well as instrumental capabilities with respect to both high spatial and energy resolution, and high power excitation sources such as synchrotron radiation.
Some evidence suggests that heart rate variability (HRV) biofeedback might be an effective way to treat anxiety and stress symptoms. To examine the effect of HRV biofeedback on symptoms of anxiety and stress, we conducted a meta-analysis of studies extracted from PubMed, PsycINFO and the Cochrane Library.
The search identified 24 studies totaling 484 participants who received HRV biofeedback training for stress and anxiety. We conducted a random-effects meta-analysis.
The pre-post within-group effect size (Hedges' g) was 0.81. The between-groups analysis comparing biofeedback to a control condition yielded Hedges' g = 0.83. Moderator analyses revealed that treatment efficacy was not moderated by study year, risk of study bias, percentage of females, number of sessions, or presence of an anxiety disorder.
HRV biofeedback training is associated with a large reduction in self-reported stress and anxiety. Although more well-controlled studies are needed, this intervention offers a promising approach for treating stress and anxiety with wearable devices.
The influence of baseline severity has been examined for antidepressant
medications but has not been studied properly for cognitive–behavioural
therapy (CBT) in comparison with pill placebo.
To synthesise evidence regarding the influence of initial severity on
efficacy of CBT from all randomised controlled trials (RCTs) in which
CBT, in face-to-face individual or group format, was compared with
pill-placebo control in adults with major depression.
A systematic review and an individual-participant data meta-analysis
using mixed models that included trial effects as random effects. We used
multiple imputation to handle missing data.
We identified five RCTs, and we were given access to individual-level
data (n = 509) for all five. The analyses revealed that
the difference in changes in Hamilton Rating Scale for Depression between
CBT and pill placebo was not influenced by baseline severity (interaction
P = 0.43). Removing the non-significant interaction
term from the model, the difference between CBT and pill placebo was a
standardised mean difference of –0.22 (95% CI –0.42 to –0.02,
P = 0.03, I2 = 0%).
Patients suffering from major depression can expect as much benefit from
CBT across the wide range of baseline severity. This finding can help
inform individualised treatment decisions by patients and their
The determination of the heights of points on the lunar surface by Earth based astronomy using the geometrical librations, although individually of low accuracy, still provides our best method of obtaining the global shape of the Moon. The intrinsic scatter of the results arises from the effects of ‘seeing’ and simple statistical analysis is required to derive valid conclusions about the shape. Baldwin's method of fitting ellipsoidal surfaces to the points on the maria and uplands, separately by the method of least squares proves to be a valuable tool.
Analyses of the ACIC points and of the Pic du Midi studies of G. A. Mills show that good first descriptions of the global shape of the Moon for both the maria and uplands are triaxial ellipsoids with their long axes within 10° of the Earth direction, the major axis of the maria being about 1.3 km smaller than that of the uplands. Of particular significance is that the ellipticity of these surfaces is about 2½ times greater than the dynamical ellipticity; thus the non-hydrostatic figure of the Moon is not simply the result of distortion from a uniform Moon during its early history. The angular variation in density within the Moon cannot be simply a phenomena within the crust but must extend to a great depth. Convection could provide an explanation.
The departures of the lunar surface from the idealised ellipsoids are also of interest. The circular maria are systematically depressed relative to the maria ellipsoid: can the mascons have adjusted isostatically since their formation? Systematic differences in height between the western and eastern southern uplands are also noted.
A new generation of solar instruments provides improved spectral, spatial, and temporal resolution, thus facilitating a better understanding of dynamic processes on the Sun. High-resolution observations often reveal multiple-component spectral line profiles, e.g., in the near-infrared He i 10830 Å triplet, which provides information about the chromospheric velocity and magnetic fine structure. We observed an emerging flux region, including two small pores and an arch filament system, on 2015 April 17 with the ‘very fast spectroscopic mode’ of the GREGOR Infrared Spectrograph (GRIS) situated at the 1.5-meter GREGOR solar telescope at Observatorio del Teide, Tenerife, Spain. We discuss this method of obtaining fast (one per minute) spectral scans of the solar surface and its potential to follow dynamic processes on the Sun. We demonstrate the performance of the ‘very fast spectroscopic mode’ by tracking chromospheric high-velocity features in the arch filament system.
14C ages were determined on samples of foraminifera separated from cores from three areas of the tropical Pacific (East Pacific Rise, Oontong Java Plateau, and South China Sea). Analyses were made on four planktonic species and on mixed benthics. The purpose of the multiple analysis on planktonic species is to assess the importance of artifacts resulting from the bioturbation-abundance change couple, from the bioturbation-partial dissolution couple and from redeposition by bottom currents. The goal is to use the benthic-planktonic age difference as a means of establishing changes in deep sea ventilation rate over the past 25,000 years. Results of a part of this work are presented in this paper.
Recently, in an intercomparison of the Hohenheim German oak chronology (Becker 1993) and the Göttingen chronology (Leuschner and Delorme 1988), an error was discovered in the former (Leuschner, in preparation). Due to an error in adding sections at 5241 bc, 41 yr are missing in the published Hohenheim chronology. After correction of the error, the two chronologies synchronize over their entire common length, back to 7200 bc.
We present the first speckle interferometric observations of R CrB, the prototype of a class of peculiar stars which undergo irregular declines in their visible light curves. The observations were carried out with the 6 m telescope at the Special Astrophysical Observatory near maximum light (V = 7, 1996 Oct. 1) and at minimum light (V = 10.61, 1999 Sep. 28). A spatial resolution of 75 mas was achieved in the K-band. The dust shell around R CrB is partially resolved, and the visibility is approximately 0.8 at a spatial frequency of 10 cycles/arcsec. The two-dimensional power spectra obtained at both epochs do not show any significant deviation from circular symmetry. The visibility function and spectral energy distribution obtained near maximum light can be simultaneously fitted with a model consisting of the central star and an optically thin dust shell with density proportional to r−2 and amorphous carbon as its constituent. The inner boundary of the shell is found to be 82 R* (19 mas) with a temperature of 920 K near maximum light. However, this simple model fails to simultaneously reproduce the visibility and spectral energy distribution obtained at minimum light. We show that this discrepancy can be attributed to thermal emission from a newly formed optically thick dust cloud. Simultaneous fits of the observed SED and visibility with models including a thermally emitting dust cloud suggest the presence of a newly formed dust cloud as hot as 1200 K with a radius of 4 – 5R*, in addition to an optically thin dust shell whose inner boundary is ~ 170 R* with a temperature of ~ 690 K. Alternatively the discrepancy can be attributed to an unusual extinction curve of dust grains in the obscuring cloud which was present in front of the star at minimum light. The details of the observations and modeling are described in Ohnaka et al. (2001, A&A 380, 212).
The center of the stellar association in 30 Doradus, R136 (HD 38268), is an unusually high concentration of massive and bright O, B and Wolf-Rayet stars and represents the closest example of an intense starburst region.
In this paper, we review our recent work on triplet harvesting (TH) and its application in white organic light-emitting diodes (OLEDs). This includes the configuration of highly efficient single unit two-color and tandem four-color white OLEDs reaching efficacies of more than 30 lm/W at 1000 cd/m², as well as the development of new blue fluorescent emitters. The new compounds are chemically designed to exhibit a high triplet energy to allow TH by a green phosphorescent emitter. In a first step towards white TH OLEDs, we fabricated blue-green TH OLEDs to prove the validity of our concept.
The effects of antidepressants for treating depressive disorders have been overestimated because of selective publication of positive trials. Reanalyses that include unpublished trials have yielded reduced effect sizes. This in turn has led to claims that antidepressants have clinically insignificant advantages over placebo and that psychotherapy is therefore a better alternative. To test this, we conducted a meta-analysis of studies comparing psychotherapy with pill placebo.
Ten 10 studies comparing psychotherapies with pill placebo were identified. In total, 1240 patients were included in these studies. For each study, Hedges’ g was calculated. Characteristics of the studies were extracted for subgroup and meta-regression analyses.
The effect of psychotherapy compared to pill placebo at post-test was g = 0.25 [95% confidence interval (CI) 0.14–0.36, I2 = 0%, 95% CI 0–58]. This effect size corresponds to a number needed to treat (NNT) of 7.14 (95% CI 5.00–12.82). The psychotherapy conditions scored 2.66 points lower on the Hamilton Depression Rating Scale (HAMD) than the placebo conditions, and 3.20 points lower on the Beck Depression Inventory (BDI). Some indications for publication bias were found (two missing studies). We found no significant differences between subgroups of the studies and in meta-regression analyses we found no significant association between baseline severity and effect size.
Although there are differences between the role of placebo in psychotherapy and pharmacotherapy research, psychotherapy has an effect size that is comparable to that of antidepressant medications. Whether these effects should be deemed clinically relevant remains open to debate.
This paper deals with fundamental molecular issues related to macroscopic mechanical properties of nano-meso-microscale montmorillonite clay particulate systems. Molecular interaction of high aspect montmorillonite particles with solvents has large influence on resulting swelling characteristics in clays consisting of montmorillonite. A new controlled uniaxial swelling (CUS) cell is designed which allows a simultaneous measurement of swelling and swelling pressure in addition to ease of removal of undisturbed samples for electron microscopic and fourier transform infrared spectroscopic investigations. Our work shows that the swelling behavior of montmorillonite directly results from breakdown of large particles to smaller nano and meso scale particles with increased water incorporation in the interlayers. The Si-O vibration band regions of the montmorillonite spectra obtained at controlled amounts of swelling from 0-100% (where 0% swelling is defined as fully saturated samples under no volume change) show changes in band shape, intensity, and positions resulting from increased H-bonding in the interlayers and surface of montmorillonite particles. In addition, orientation dependant micro-attenuated total reflectance (ATR) spectroscopic investigations are also conducted on the controlled swelled samples. Our results indicate that the reduced particle size with increased swelling is related to increased misorientation of the montmorillonite platelets. The relationship between molecular interactions microstructure and macroscopic response (swelling and swelling pressure) is the key to development of novel nanocomposite systems based on montmorillonite with tailored properties.
Red light emitting Eu3+ doped Y2O3 phosphor nano-particles were synthesized by a solgel method combined with a furnace firing. The particle size, measured using dynamic light scattering (DLS), was between36nm and 1 micron depending on the conditions. Final dopant concentrations were measured through inductively coupled plasma (ICP). The ICP results show a dopant loss of 58% during the processing for the europium doped yttria. Red photoluminescence (PL) and cathodoluminescence (CL), at 614nm was observed from the phosphor particles under UV excitation and electron bombardment. Results show that the samples with a mean diameter of 30nm displayed a significant increase in PL brightness over the samples whose mean diameter was 215nm. The lag in PL, and CL intensity behind the commercial reference samples is attributed to the significantly lower dopant levels present in the experimental phosphors. Results also indicate that these processing methods and nanophosphors may be a useful alternative to current materials and methods.
Particles of BaSO4 with sizes in nano-scale and micro-scale ranges were investigated for their interactions with fibroblasts in order to determine the biocompatibility of nano-sized particles. Cells were incubated in the presence of particles at 1, 10 and 100 times the particle to cell surface area ratio and at a single concentration of 0.138 mg/ml. Production by the fibroblasts of an inflammatory cytokine in response to the particles was measured and the effect of particle size and volume on cell viability was examined. All particles were cell associated and some agglomeration was visible at all size ranges. Release of interleukin-6 by cells subjected to the same concentration of Ba SO4was similar to control levels, while addition of 1x surface area ratio (SAR) of particles to cells resulted in an increase in IL-6 from 94 pg/ml for 100 nm particles to 218 pg/ml with 2 μm particle diameter. By increasing particle to cell surface area ratios from 1× to 100x, cell viability was compromised for the 2μm particles but was not affected by the nanometer sized BaSO4 particles.
Oriented ferromagnetic FePt nanoparticles with the face-centered tetragonal L10 structure were produced in Al2O3 single crystal hosts by ion implantation and annealing. Both the orientation and particle-size of the FePt particles depend strongly on the implantation conditions. The magnetic coercivities are extremely high, reaching values in excess of 20 kOe for Pt concentrations of ∼45% in the FePt alloy. Ferromagnetic FePt nanoparticles were also produced in amorphous SiO2 by ion implantation and annealing.
We report electron microscopy studies of nanoparticles ( 500 ≤ n ≤ 104, where n is the number of atoms in a given cluster) that are sputtered from the surface by high-energy ion impacts. Measurements of the sizes of these clusters yielded an inverse power-law distribution with an exponent of –2 that is independent of irradiating ion species and total sputtering yield. This inverse-square dependence indicates that these nanoclusters are produced when shock waves, generated by sub-surface displacement cascades, impact and ablate the surface. Such nanoparticles consist of simple fragments of the original surface, i.e., ones that have not undergone any large thermal excursion. As discussed below, this “ion ablation” technique should therefore be useful for synthesizing nanoparticles of a wide variety of alloy compositions and phases.
Multilayers consisting of two immiscible components (e.g. Fe/Ag Fe/Au or Ni/NiO) could by transformed by an annealing process into a nanostructured system of non statistically distributed nearly spherical particles in a surrounding matrix of the complementary component. The non statistical arrangement of the particles and the dynamics of the disintegration process strongly depend on the initial interface energy, i.e. the local interface curvature and the local interfacial stress. Detailed microstructure investigations of the different systems are used to interpret the measured transport properties.
Cu-nanoclusters can be produced in an electrochemical environment by tip-induced metal deposition using an electrochemical scanning tunneling microscope (EC-STM). These clusters, consisting of 100-1000 atoms only, show a surprising stability against anodic oxidation. The clusters, which are 2-3 atomic layers in height dissolve slowly when the applied potential is increased step by step to 200 mV positive of the reversible Nernst potential for “normal” copper dissolution. The presented work gives evidence that the unusual stability of the clusters could be a consequence of interfacial alloying between the cluster and the underlying substrate. In order to study these effects Cu-nanoclusters have been produced on pure gold substrates and on carefully prepared Au3Cu(111)-substrates. This work compares the results obtained on both substrates.