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Serotonergic neurotransmission plays a key role in seasonal changes of mood and behaviour. Higher serotonin transporter availability in healthy human subjects in times of lesser light has been reported in recent studies. Furthermore, seasonal alterations of postsynaptic serotonin-1A receptors have been suggested by a recent animal study. Following that, this study aimed at identifying seasonal alterations of serotonin-1A receptor binding in the living human brain.
Thirty-six healthy, drug-naïve subjects were investigated using PET and the specific tracer [carbonyl-11C]WAY-100635. Regional serotonin-1A receptor binding (5-HT1A BPND) was related to the individual exposure to global radiation. Furthermore, the subjects were divided into two groups depending on individual exposure to global radiation, and the group differences in regional 5-HT1A BPND were determined.
Correlation analysis controlled for age and gender revealed highly significant positive correlations between regional postsynaptic 5-HT1A BPND and global radiation accumulated for 5 days (r=.32 to .48, p=.030 to .002). Highly significant differences in 5-HT1A BPND binding between subjects with low compared to high exposure to global radiation were revealed (T=-2.63 to -3.77, p .013 to .001). 20% to 30% lower 5-HT1A BPND was found in the subject group exposed to lower amount of global radiation.
Seasonal factors such as exposure to global radiation influence postsynaptic serotonin-1A receptor binding in various brain regions in healthy human subjects. In combination with seasonal alterations in serotonin turnover and 5-HTT availability revealed in recent studies, our results provide an essential contribution of molecular mechanisms in seasonal changes of human serotonergic neurotransmission.
Background: Flow cytometry in the cerebrospinal fluid (CSF) is used as an adjunct to cytology to increase the sensitivity of detecting central nervous system (CNS) lymphoma. We aim to evaluate CSF flow cytometry as a diagnostic tool for lymphoma in patients presenting with undifferentiated neurologic symptoms. Methods: We retrospectively reviewed all CSF flow cytometry samples sent in the Calgary region from 2012-2015. Clinical data, laboratory investigations, radiologic imaging studies, and pathological data were analyzed. Clinical review extended to 2 years post CSF flow cytometric testing. Results: The number of samples of CSF flow cytometry that were positive for a hematological malignancy was 43/763 (5.6%). The overall sensitivity of the test was 72.9%. A positive result was more likely to occur in patients with a prior history of a hematological malignancy or abnormal enhancement on MRI (p<0.0001). In fact, CSF flow cytometry was negative in all patients who did not have a previous hematological malignancy or abnormal enhancement on MRI (n = 247). Conclusions: CSF flow cytometry has very limited role in the screening for primary CNS lymphoma, unless a strictly endorsed testing algorithm is applied. It is, however, an invaluable tool in assessing CNS involvement in patients with previous diagnosis of hematolymphoid malignancy.
To study the molecular epidemiology of vancomycin-resistant Enterococcus (VRE) colonization and to identify modifiable risk factors among patients with hematologic malignancies.
A hematology-oncology unit with high prevalence of VRE colonization.
Patients with hematologic malignancies and hematopoietic stem cell transplantation recipients admitted to the hospital.
Patients underwent weekly surveillance by means of perianal swabs for VRE colonization and, if colonized, were placed in contact isolation. We studied the molecular epidemiology in fecal and blood isolates by pulsed-field gel electrophoresis over a 1-year period. We performed a retrospective case-control study over a 3-year period. Cases were defined as patients colonized by VRE, and controls were defined as patients negative for VRE colonization. Case patients and control patients were matched by admitting service and length of observation time.
Molecular genotyping demonstrated the primarily polyclonal nature of VRE isolates. Colonization occurred at a median of 14 days. Colonized patients were characterized by longer hospital admissions. Previous use of ceftazidime was associated with VRE colonization (P < .001), while use of intravenous vancomycin and antibiotics with anaerobic activity did not emerge as a risk factor. There was no association with neutropenia or presence of colonic mucosal disruption, and severity of illness was similar in both groups.
Molecular studies showed that in the majority of VRE-colonized patients the strains were unique, arguing that VRE acquisition was sporadic rather than resulting from a common source of transmission. Patient-specific factors, including prior antibiotic exposure, rather than breaches in infection control likely predict for risk of fecal VRE colonization.
Solid-state based battery technology offers, in principle, the largest temperature range (from room temperature to 500 °C) of any battery technology. In fluoride based batteries, the chemical reaction used to create electrical energy is a solid-state reaction of a metal with fluoride anion . Among the various types of solid preparation techniques, the mechanochemical synthesis has been recognized as a powerful route to novel, high-performance, and low-cost materials . Thus, a mixed and highly disordered fluoride phase with retained cubic symmetry can be obtained with a very high Fˉ diffusivity .
In our group, a series of new electrolytes was developed, namely LaF3-BaF2-KF solid solutions, using mechanosynthesis method. The cubic structure of the product was confirmed by XRD. The nanoscale nature and morphology of the samples were characterized by SEM and TEM. First Solid-state electrochemical cells were built with LiF based composite cathode, LaF3-BaF2-KF derived electrolyte and Fe based composite anode.
In low vaccination coverage regions (LVR) in The Netherlands people often reject participation in the National Immunization Programme for religious reasons. During a rubella epidemic in 2004–2005, 32 pregnant women were notified with rubella, and 11 babies were born with defects related to maternal infection. This study presents a cost-utility analysis of a screening and vaccination programme for rubella focusing on three scenarios: (1) screening non-vaccinated pregnant women in LVR; (2) screening all pregnant women in LVR; (3) screening all non-vaccinated pregnant women in The Netherlands (including pregnant first-generation non-Western immigrant women). Cost-utility was estimated over a 16-year period which included two rubella outbreaks. Observed complications from the 2004–2005 epidemic were used to estimate average cost savings and quality-adjusted life-years (QALY) gained. The programme would be cost-effective (€1100/QALY gained) when assuming an acceptability of vaccination of 20% in women belonging to orthodox protestant risk groups.
We report the first population-based case-control study on acute hepatitis B in a very low-incidence country. A case was a Netherlands resident, notified between May 1999 and July 2000 with symptoms and serology compatible with acute hepatitis B. Population controls were randomly selected, with oversampling from men and persons aged 20–39 years. Risk factors were studied using logistical regression, distinguishing confounders and mediators through hierarchical analysis. Participants were 120 cases and 3948 controls. The risk of acute hepatitis B was increased in men who have sex with men, with reporting to have had more than two partners in the past 6 months the only significant risk. In children, adult females and heterosexual males, having parents born in a hepatitis B endemic country was a significant risk. For adult females and heterosexual males, this was largely explained by having a foreign partner. For children this was partly explained by parenteral exposures abroad.
Using molecular beams, polycrystalline thin CuInS2 (CIS) films of different thicknesses were grown on Si substrates covered with a sputtered Mo-buffer layer. Systematic photoluminescence and photoreflectance measurements were performed to investigate the influence of strain - introduced during growth - on the optical properties. The transition energy of the free A-exciton (FXA) decreases with increasing tensile strain caused by (i) increasing thickness of the Mo buffer layer and (ii) decreasing thickness of the CIS layer. Furthermore, the energetic splittings between FXA, FXB, and FXC increase with increasing tensile strain. When combined with X-ray diffraction data, the oscillator strengths of the excitonic transitions yield information on the strain distribution within the films.
The amounts of cesium and uranium released from crushed spent PWR fuel in the gel-state clays with a few ml of supernatant at hot cell temperature under Ar-atmosphere have been measured. The fractions of cesium dissolved from the fuel for 873 days were 0.29 and 0.25% in Boom clay/Boom-clay water and Ca-bentonite/synthetic granitic groundwater, respectively. These cesium fractions were very close to the gap inventory of cesium, which was determined to be around 0.30% in the previous experiment. The fraction of uranium released up to 193 days in the Boom clay media was 0.011% and this fraction has been retained until 873 days. Such this phenomenon was also obtained in the Ca-bentonite media even though the released fraction was higher than that in Boom clay. The increase of less than 0.001% in the dissolved uranium fraction between 193 and 873 days suggests that the long-term leach rate of uranium from spent fuel would be much less than 24 μg·m−2·day−1.
The wide bandgap semiconductor TiO2 has become the dominant UV-activated photocatalyst in the field of air and water detoxification because of its high stability, low cost, high oxidation potential and chemically favorable properties. The demand for visible-light activated photocatalytic systems is increasing rapidly; however, currently, the efficiency and availability of photocatalysts that can be activated effectively by the solar spectrum and particularly indoor lighting is severely limited. In this paper, a new coprecipitation/hydrolysis synthesis route is used to create a TiO2-ZnFe2O4 nanocomposite that is directed towards extending the photoresponse of TiO2 from UV to visible wavelengths (>400nm). The effect of TiO2's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe2O4 narrow bandgap semiconductor is evaluated. The transformation's dependence on pH, calcination temperature, particle size, and ZnFe2O4 concentration has been analyzed using XRD, SEM, and UV-Visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe2O4 nanocomposite are outlined. The visible-light activated photocatalytic activity of the TiO2-ZnFe2O4 nanocomposites have been compared to an Aldrich TiO2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.
Nanocrystalline tin oxide powder was prepared using a solution precipitation technique after adding the surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT). Powders were characterized using X-ray diffraction (XRD), surface area (BET) and transmission electron microscopy (TEM). The gas sensitivity for surfactant added powders increased for liquid petroleum gas (LPG) as well as compressed natural gas (CNG), due to the decreased particle size and the increased surface area. The LPG gas sensitivity increased several times using phosphorus treated surfactant AOT.
Nano-structured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers and selective reduction/oxidation of different class of organic compounds. Nano-structured TiO2 is widely used as a photocatalyst for the effective decomposition of organic compounds in air and water under UV radiation. On the other hand, the development of visible light activated photocatalysis, for utilizing the available solar energy remains a challenge and requires low band gap materials as sensitizer. Among the various inorganic sensitizers, bulk CdS with an Eg of 2.5 eV and an energetically high-lying conduction band has been identified as a potential candidate. This can be coupled with a large band gap semiconductor (TiO2 with Eg ∼ 3.2 eV) for visible light photocatalysis and solar energy conversion. In the CdS sensitized TiO2 nano-composite system, charge injection from the conduction band of the semiconductor sensitizer to that of TiO2 can lead to an efficient and longer charge separation by minimizing electron-hole recombination. In the present paper, we have carried out a systematic synthesis of nano-structured CdS/TiO2 via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS/TiO2 nano-composites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water.
A highly doped n-type silicon wafer is anodized in an aqueous hydrofluoric acid solution to generate a porous silicon skeleton with a convenient morphology. After drying, the mesoporous sample is exposed to an electrodeposition process in which the pores are filled with the ferromagnetic metal Ni. Anodization and deposition of Ni lead to a ferromagnetic nanoscopic system which shows an interesting behaviour in the high field range (> 3 T). In addition to the expected low field switching below 500 Oe a second switching at fields of a few Tesla with a steep slope is also present. This feature with its extremely high sensitivity for changes of the external magnetic field gives rise to high magnetic field sensor applications based on a silicon technology.
Modeling of high resolution nitrogen adsorption isotherms by the Grand Canonical Monte Carlo (GCMC) method for zirconia-pillared clays containing 20 wt.% of ZrO2 revealed that the pillars are comprised of separate Zr4(μ-OH)8(OH)m (H2O)n units (Zr4 tetramers) and their dimers (Zr8 complexes) as sheets or loose 3D structures. This agrees with the results of modeling of the condensation process in solution using the Density Functional Theory approach (DFT) and the semiempirical PM3 method. Bridging and terminal hydroxyls strongly bound with Zr cations are involved in anchoring supported Cu cations and Pt. This nanostructure of the active component as well as the developed micro- and mesoporosity appear to be responsible for the high performance of Pt+Cu/ZrPILC catalysts in the NOx selective reduction by propylene and decane in realistic feeds.
Long and fine Zn1-xCdxSe pseudo-binary alloy nanowires of various compositions x covering the entire range were grown by metalorganic chemical vapor deposition, using diethlyzinc, dimethylcadmium and diisopropylselenide as precursors, on Si (100) and GaAs (100) substrates; sputtered gold was used as a catalyst to promote nanowire formation. By controlling the ratio of the flows of the precursors, the temperature and the pressure during growth, we obtained nanowires of desired compositions. The morphology, structure and optical properties of the nanowires were studied by various techniques, including secondary electron microscopy, atomic force microscopy, transmission electron microscopy, X-ray diffraction, photoluminescence, and Raman scattering. Depending on the substrate, composition and conditions of growth, either the zincblende or wurtzite nanowires were obtained. At compositions where the stable form would have been normally wurtzite, the zincblende form could be obtained under certain growth conditions. From the orientations of the ordered nanowires on the substrate surface, their directions of growth were deduced and confirmed by high resolution lattice imaging. The relationship between the band gap and the composition of the nanowires were measured and found to deviate from that of bulk alloys and epilayers. The interplay between the growth conditions and compositions and morphology of the nanowires are discussed.
Polymer-inorganic hybrid materials composed of polymethyl methacrylate (PMMA) and zinc compounds were prepared by sol-gel in-situ transition polymerization of zinc complex in PMMA matrix. Zinc acetate dihydrate dissolved in ethanol was used as the inorganic precursor. Monoethanolamine (MEA) acted as a complexing agent to control the hydrolysis of zinc acetate to produce a zinc compound network, and then PMMA, formed in-situ through a radical polymerization, were chemically bonded to the forming zinc compound network to realize a hybrid material. Transparent homogenous hybrid materials with slight colours from pink to yellow were fabricated by varying the composition. TEM, FT-IR were employed to investigate structural and physical properties. The UV-shielding effect was evaluated by UV-VIS. The low content of zinc (around 0.02 wt%) and the fine particle size rendered it visibly transparent and capable of greatly attenuating UV radiation in the full UV range.
Recent progress in experimental technique made it possible to improve the sensitivity of microwave detected photoconductivity by several orders of magnitude. This opens completely new possibilities for a contact less non-destructive electrical defect characterization of silicon wafers and even of epitaxial layers on substrates with extremely low resistivity. Electrical properties such as lifetime, mobility and diffusion length can be measured without contacts also at very low injection levels with a resolution only limited by the diffusion length of the charge carriers. The doping level of the material plays no major role.
Owing to the high sensitivity, thermal excitation of charge carriers out of defect levels filled during the photo pulse can also be observed. This leads to defect specific photoconductivity transients which deliver pieces of information like DLTS, however, again without contacts, non critical doping, and with high spatial resolution.