The role of contaminations in ion beam spectroscopy with freestanding 2D materials: A study on thermal treatment.

As surface-only materials, freestanding 2D materials are known to have a high level of contamination-mostly in the form of hydrocarbons, water, and residuals from production and exfoliation. For well-designed experiments, it is of particular importance to develop effective cleaning procedures, especially since standard surface science techniques are typically not applicable. We perform ion spectroscopy with highly charged ions transmitted through freestanding atomically thin materials and present two techniques to achieve clean samples, both based on thermal treatment. Ion charge exchange and energy loss are used to analyze the degree of sample contamination. We find that even after cleaning, heavily contaminated spots remain on single layer graphene. The contamination coverage, however, clusters in strand-like structures leaving large clean areas. We present a way to discriminate clean from contaminated areas with our ion beam spectroscopy if the heterogeneity of the surface is increased sufficiently enough. We expect a similar discrimination to be necessary in most other experimental techniques.

2D X-ray radiography of imploding capsules at the national ignition facility.

First measurements of the in-flight shape of imploding inertial confinement fusion (ICF) capsules at the National Ignition Facility (NIF) were obtained by using two-dimensional x-ray radiography. The sequence of area-backlit, time-gated pinhole images is analyzed for implosion velocity, low-mode shape and density asymmetries, and the absolute offset and center-of-mass velocity of the capsule shell. The in-flight shell is often observed to be asymmetric even when the concomitant core self-emission is round. A ∼ 15 µm shell asymmetry amplitude of the Y(40) spherical harmonic mode was observed for standard NIF ICF hohlraums at a shell radius of ∼ 200 µm (capsule at ∼ 5× radial compression). This asymmetry is mitigated by a ∼ 10% increase in the hohlraum length.

Iron-doped Pt-TiO2 nanotubes for photo-catalytic water splitting.

In this work we report on the photo-catalytic performance of phase-pure and iron-doped anatase and rutile nanotubes, produced via a sol-gel process using pristine carbon nanotubes as templates. The encapsulated iron residues can be used to in situ dope the TiO(2) nanotubes without phase separation. The anatase and rutile nanotubes were further impregnated with platinum crystals with a uniform dispersion and an average size of approximately 2 nm. The materials showed dramatically improved activities for the photo-catalytic splitting of water compared to commercial TiO(2) with similar surface area (up to two orders of magnitudes), due to their higher illumination area, extended absorption range and reduced electron-hole recombination rate. The homogeneous dispersion of platinum nanoparticles further increased the hydrogen evolution rate for anatase nanotubes by a factor of seven in comparison to that for the pristine material, thus proving the great potential for commercial applications.

Alternative method to characterize continuous and discontinuous phase transitions in surface reaction models.

In this paper we revisited the Ziff-Gulari-Barshad model to study its phase transitions and critical exponents through time-dependent Monte Carlo simulations. We use a method proposed recently to locate the nonequilibrium second-order phase transitions and that has been successfully used in systems with defined Hamiltonians and with absorbing states. This method, which is based on optimization of the coefficient of determination of the order parameter, was able to characterize the continuous phase transition of the model, as well as its upper spinodal point, a pseudocritical point located near the discontinuous phase transition. The static critical exponents ß, ν_{∥}, and ν_{⊥}, as well as the dynamic critical exponents θ and z for the continuous transition point, were also estimated and are in excellent agreement with results found in literature.

Non-destructive functionalisation for atomic layer deposition of metal oxides on carbon nanotubes: effect of linking agents and defects.

The hybridisation of metal oxides and nanocarbons has created a promising new class of functional materials for environmental and sustainable energy applications. The performance of such hybrids can be further improved by rationally designing interfaces and morphologies. Atomic layer deposition (ALD) is among the most powerful techniques for the controlled deposition of inorganic compounds, due to its ability to form conformal coatings on porous substrates at low temperatures with high surface sensitivity and atomic control of film thickness. The hydrophobic nature of the nanocarbon surface has so far limited the applicability of ALD on CNTs. Herein we investigate the role of structural defects in CNTs, both intrinsic and induced by acid treatment, on coverage, uniformity and crystallinity of ZnO coatings. Furthermore, we demonstrate the potential of small aromatic molecules, including benzyl alcohol (BA), naphthalene carboxylic acid (NA) and pyrene carboxylic acid (PCA), as active nucleation sites and linking agents. Importantly, only PCA exhibits sufficiently strong interactions with the pristine CNT surface to withstand desorption under reaction conditions. Thus, PCA enables a versatile and non-destructive alternative route for the deposition of highly uniform metal oxide coatings onto pristine CNTs via ALD over a wide temperature range and without the typical surface corrosion induced by covalent functionalisation. Importantly, preliminary tests demonstrated that the improved morphology obtained with PCA has indeed considerably increased the hybrid's photocatalytic activity towards hydrogen evolution via sacrificial water splitting. The concept demonstrated in this work is transferable to a wide range of other inorganic compounds including metal oxides, metal (oxy)nitrides and metal chalcogenides on a variety of nanocarbons.

Circadian temperature and cortisol rhythms during a constant routine are phase-delayed in hypersomnic winter depression.

Circadian temperature, cortisol, and thyroid-stimulating hormone (TSH) rhythms during a constant routine were assessed in 6 female controls and 6 female patients with hypersomnic winter depression (seasonal affective disorder, SAD) before and after morning bright light treatment. After sleep was standardized for 6 days, the subjects were sleep-deprived and at bed rest for 27 hours while rectal temperature, cortisol, and TSH levels were assessed. The minimum of the fitted rectal temperature rhythm was phase-delayed in the SAD group compared to the controls 5:42 AM vs. 3:16 AM (p < .005); with bright light treatment, the minimum advanced from 5:42 AM to 3:36 AM (p = .06). The minimum of the cortisol rhythm was phase-delayed in the SAD group compared to the control group, 12:11 AM vs. 10:03 PM (P < .05); with bright light treatment, the minimum advanced from 12:11 AM to 10:38 PM (P = .06) [corrected]. The acrophase of the TSH rhythm was not significantly phase-delayed in SAD subjects compared to control, though the trend appeared to be toward a phase-delay (p = .07). After bright light therapy, the TSH acrophase was not significantly different in the SAD subjects; the trend was a phase-advance (p = .09). Overall, the data suggest that circadian rhythms are phase-delayed relative to sleep in SAD patients and that morning bright light phase-advances those rhythms.

Dawn simulation and bright light in the treatment of SAD: a controlled study.

BACKGROUND: Some small controlled studies have found that dawn simulation is effective in treating seasonal affective disorder (SAD). With a larger sample size and a longer duration of treatment, we compared dawn simulation with bright light therapy and a placebo condition in patients with SAD. METHOD: Medication-free patients with SAD were randomly assigned to one of three conditions: bright light therapy (10,000 lux for 30 min, from 6:00 AM to 6:30 AM), dawn simulation (1.5 hour dawn signal from 4:30 AM to 6:00 AM peaking at 250 lux), and a placebo condition, a dim red light (1.5 hour dawn signal from 4:30 am to 6:00 AM peaking at 0.5 lux.) Over the subsequent 6 weeks, the subjects were blindly rated by a psychiatrist using the Structured Interview Guide for the Hamilton Depression Rating-Seasonal Affective Disorder Version (SIGH-SAD). We modeled the profiles of the remissions (SIGH-SAD < or = 8) and response (> or =50% decrease in SIGH-SAD) to treatment over time using Cox proportional hazards models. RESULTS: The sample consisted of 95 subjects who were randomized to the three conditions: bright light (n = 33), dawn simulation (n = 31) and placebo (n = 31). Dawn simulation was associated with greater remission (p <.05) and response (p <.001) rates compared to the placebo. Bright light did not differ significantly from the placebo. Dawn simulation was associated with greater remission (p <.01) and response (p <.001) rates compared to the bright light therapy. The mean daily hours of sunshine during the week before each visit were associated with a significant increase in likelihood of both remission (p <.001) and response (p <.001). CONCLUSIONS: Dawn simulation was associated with greater remission and response rates compared to the placebo and compared to bright light therapy. The hours of sunshine during the week before each assessment were associated with a positive clinical response.

Late recovery of auditory comprehension in global aphasia. Improved recovery observed with subcortical temporal isthmus lesion vs Wernicke's cortical area lesion.

This study examined the relationship between recovery of auditory comprehension in global aphasia patients after 1 year post onset, and temporal lobe lesion in Wernicke's cortical area vs temporal lobe lesion in the subcortical temporal isthmus area. Computed tomographic scans and language behavior were examined in 14 right-handed globally aphasic stroke patients with lesion in the left hemisphere. Nine patients had large cortical/subcortical frontal, parietal, and temporal lobe lesion that included more than half of Wernicke's cortical area (FPT cases). Five patients had large cortical/subcortical frontal and parietal lobe lesion, but only subcortical temporal lobe lesion, including the temporal isthmus (FPTi cases). All patients were tested acutely at 1 to 4 months post onset and again at 1 to 2 years post onset. There was a significantly greater increase in the amount of recovery that had taken place after 1 to 2 years post onset for the FPTi group vs the FPT group in the overall Boston Diagnostic Aphasia Examination (BDAE) Auditory Comprehension Z score. In four of the five FPTi cases, the late BDAE Auditory Comprehension Z scores were above -0.5 (mild-to-moderate comprehension deficits). Most recovery was in single-word comprehension. In eight of the nine FPT cases, the late BDAE Auditory Comprehension Z-scores were below -0.5 (moderate-to-severe comprehension deficits). There was no significant difference between the two groups in recovery of spontaneous speech, repetition, or naming, where severe deficits remained in most cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Outcome in severe pediatric Guillain-Barré syndrome after immunotherapy or supportive care.

We reviewed duration of illness in 26 children with severe pediatric Guillain-Barré syndrome (GBS) during two contiguous 8-year periods that represent a "non-treatment era" of supportive care alone or a "treatment era" of supportive care plus either plasma exchange or intravenous immunoglobulin intervention. Our findings of similar recovery times in each treatment group suggest that immunotherapy in severe pediatric GBS may be less effective than in adult GBS, or effective only when given to certain patients very early in the course of the illness.

Proprioceptive evoked potentials in man: cerebral responses to changing weight loads on the hand.

We studied cerebral evoked potentials on the scalp to the stimulation of the right hand from a change in weight of 400-480 g in ten subjects. Rise-time was 20g/10 ms, Inter Stimulus Interval 2s and stimulus duration was 100 ms. The cerebral activations were a double positive contralateral C3'/P70, P190, and a single negative frontal Fz/N70 component. We conclude that a brisk change of a hand held load elicits a significant evoked potential (EP) unlike the electrical somato-sensory EP (SEP). The stimulus is perceived as applied force. For this reason we call it a proprioceptive EP (PEP). Further studies of the PEP are needed to assess the influence of load manipulations and of muscle contraction and to explore the effect of attentional manipulation.

Experimental and computational laser tissue welding using a protein patch.

An in vitro study of laser tissue welding mediated with a dye-enhanced protein patch was conducted. Fresh sections of porcine aorta were used for the experiments. Arteriotomies were treated using an indocyanine green dye-enhanced collagen patch activated by an 805-nm continuous-wave fiber-delivered diode laser. Temperature histories of the surface of the weld site were obtained using a hollow glass optical fiber-based two-color infrared thermometer. The experimental effort was complemented by simulations with the LATIS (LAser-TISsue) computer code, which uses coupled Monte Carlo, thermal transport, and mass transport models. Comparison of simulated and experimental thermal data indicated that evaporative cooling clamped the surface temperature of the weld site below 100 °C. For fluences of approximately 200 J/cm2, peak surface temperatures averaged 74°C and acute burst strengths consistently exceeded 0.14×106 dyn/cm (hoop tension). The combination of experimental and simulation results showed that the inclusion of water transport and evaporative losses in the computer code has a significant impact on the thermal distributions and hydration levels throughout the tissue volume. The solid-matrix protein patch provided a means of controllable energy delivery and yielded consistently strong welds. © 1998 Society of Photo-Optical Instrumentation Engineers.

A mixed modality paradigm for recording somatosensory and auditory P50 gating.

Significant somatosensory evoked potential (SEP) P50 gating has previously been found in young healthy men by the use of identical paired stimuli. In this study, the exploration of the gating paradigm was extended with the addition of a mixed modality paradigm where three different pairs of identical stimuli (clicks, right median nerve electric stimulations and proprioceptive stimuli of changing load on a handheld weight) were presented over a 12-s cycle. In both modalities repeated measures analyses of variance demonstrated no effect of paradigm. This mixed-modality recording paradigm could be used in further experiments to examine gating deficits across modalities.

Gating of the vertex somatosensory and auditory evoked potential P50 and the correlation to skin conductance orienting response in healthy men.

A defect in auditory evoked potential (AEP) P50 gating supports the theory of information-processing deficits in schizophrenia. The relationship between gating of the mid-latency evoked potentials (EP) in the somatosensory and the auditory modalities has not been studied together before. In schizophrenia, we might expect the processing deficits to act on multiple modalities. We have examined the gating of median nerve somatosensory EP (SEP) following paired stimulation identical to the AEP P50 gating paradigm using interstimulus intervals (ISI) of 500, 750 and 1000 ms and the correlation of gating to the skin conductance orienting response (SCOR) in 20 healthy men. We measured mid-latency vertex components (SEP: P50, N65, P85 and N100; AEP: P30, N45, P50 and N80). The gating was most pronounced at ISI 500 ms where the SEP P50 and N100 gating were 0.59 and 0.37, respectively, as compared to a gating of 0.61 in P30, 0.33 in P50 and 0.45 in N80 in the AEP. Repetition effects in the two modalities were not correlated. AEP P50 gating was correlated to skin conductance level (SCL). The combination of recording repetition effects on the mid-latency EP in two modalities could provide a method for investigating if deficits of information processing in schizophrenia are cross-modal.

Violence and its prediction at a psychiatric hospital.

Aggressive behaviour in psychiatric inpatients was assessed before and after a training course for staff members. The Social Dysfunction Aggression Scale (SDAS) was used to report and assess aggressive behaviour over time, and the Staff Observation Aggression Scale (SOAS) to report and assess single aggressive incidents. In addition, the numbers of nursing staff members who were on sick leave because of injuries in the periods before and after the course were recorded and compared. No statistically significant reduction was found in the number of aggressive patients or in the number of staff members on sick leave. One interesting finding was a lower reporting on the SOAS of perceived aggressive incidents after the training course in comparison with the SDAS reports. Directed verbal aggressiveness and violence towards things were found to be predictors of violence.

Plasma homocysteine and methionine concentrations in children with neural tube defects.

Mild to moderate homocysteinemia in women has been associated with an increased frequency of pregnancies with neural tube defects (NTD). Homocysteinemia is also an independent risk factor for premature vascular disease. In addition to folic acid, supplemental Vitamin B12, Vitamin B6 and betaine may normalize homocysteine metabolism, decrease the risk for NTD formation, and correct related metabolic imbalances in children with NTD. By means of automated amino acid analysis, we assessed total non-fasting homocysteine and methionine in plasma from 24 children with myelomeningocele. This study group (mean age 10.5 +/- 4.9 years) included 12 girls and 12 boys randomly selected from our Birth Defects Clinic. Homocysteine concentrations in our patients (4.7 +/- 1.8 mumol/L) did not differ from those of 20 randomly selected child controls (5.1 +/- 2.6 mumol/L). The mean homocysteine concentration for 36 adult controls (9.3 +/- 3.0 mumol/L) was significantly higher than the mean for either group of children (p < 0.0001). Linear regression analysis revealed negative correlation of total plasma homocysteine with serum folate (r = -0.53; p = 0.01), but not of homocysteine with either methionine or B12. Plasma methionine concentrations from our patients did not differ from adult reference values. Elevated homocysteine in some mothers of children with NTD has been attributed to defective methylation of homocysteine. These preliminary results do not indicate such a defect in the children themselves. A more comprehensive study of homocysteine, methionine and related metabolites in children with NTD and age-matched controls will be required to determine the clinical significance of these findings.

Comparison of erythrocyte antioxidant enzyme activities and embryologic level of neural tube defects.

Increased exposure to oxidant-derived free radicals or inadequate systems for antioxidant defense could alter cellular response at critical points in development. We measured 5 antioxidant enzymes, glutathione peroxidase (GSH-Px), glutathione reductase, glutathione-S-transferase, catalase and superoxide dismutase in erythrocytes and their plasma cofactor trace elements (Se, Zn, Cu) in 37 children with myelomeningocele and in 37 age-matched controls. We placed the patients into 3 groups according to motor level of the lesion at birth. We found significantly lower GSH-Px activities (p = 0.007) in children with myelomeningocele. For paired comparisons among the 3 patient groups and controls, there were significant differences (p < 0.05) between controls and both high (thoracic) and raid (lumbar) level embryologic lesions. The finding of antioxidant enzyme variations in our patients with myelomeningocele may indicate a role for abnormal oxidative metabolism in the development of this defect. The contribution of oxidative stress to human birth defects warrants investigation. We discuss potential relationships between oxidative stress and energy metabolism during primary neurulation.

Acupuncture in the treatment of paralysis in chronic and acute stroke patients--improvement correlated with specific CT scan lesion sites.

A total of 20 stroke patients received acupuncture, including 10 chronic and 10 acute patients; 19 of the 20 patients (95%) could be correctly classified regarding beneficial response to acupuncture, versus poor response, based on CT scan lesion site data, alone. Patients with beneficial response had damage to less than half of the motor pathway areas on CT scan, especially in the periventricular white matter area (PVWM) at the level of the body of the lateral ventricle. Overall, 8 of the 20 patients receiving acupuncture had beneficial response with measurable objective improvement in motor function, including 3 of the 10 chronic patients treated at > 3 months poststroke, and 5 of the 10 acute patients treated at < 3 months poststroke. Among the 8 patients with beneficial response, significant improvements were observed in knee flexion, knee extension, and shoulder abduction. Neither age, nor months poststroke when acupuncture was begun, was significantly correlated with the total number of improved tests, post-acupuncture. Two chronic patients with beneficial response first began receiving acupuncture at 3 years and 6 years poststroke. Most improvements were sustained for at least 4 months after the last acupuncture treatment.

Soft x-ray images of the laser entrance hole of ignition hohlraums.

Hohlraums are employed at the national ignition facility to convert laser energy into a thermal x-radiation drive, which implodes a fusion capsule, thus compressing the fuel. The x-radiation drive is measured with a low spectral resolution, time-resolved x-ray spectrometer, which views the region around the hohlraum's laser entrance hole. This measurement has no spatial resolution. To convert this to the drive inside the hohlraum, the size of the hohlraum's opening ("clear aperture") and fraction of the measured x-radiation, which comes from this opening, must be known. The size of the clear aperture is measured with the time integrated static x-ray imager (SXI). A soft x-ray imaging channel has been added to the SXI to measure the fraction of x-radiation emitted from inside the clear aperture. A multilayer mirror plus filter selects an x-ray band centered at 870 eV, near the peak of the x-ray spectrum of a 300 eV blackbody. Results from this channel and corrections to the x-radiation drive are discussed.