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Detection of important biological molecules using surface-enhanced Raman scattering (SERS) has become widely used because of the highly sensitive and label free approach offered by SERS as well as the low cytotoxic response from some SERS substrates. Gold nanoparticles are commonly used in SERS studies; however, the inherent instability of these metal nanostructures in solution adversely influences the reproducibility and quantitative nature of these measurements. Furthermore, the metal surface often denatures biomolecules upon their direct interaction. To combat this incompatibility and improve optical stability, gold nanoparticles have been encapsulated in silica shells. These Au@SiO2 nanostructures have been used extensively in cellular studies, but their SERS capabilities are generally limited to uses that include silica-entrapped SERS reporter molecules rather than direct SERS detection. This work focuses on combating these limitations via the fabrication of Au@SiO2 nanoparticles with porous silica membranes for the direct detection of target molecules in solution. Gold nanoparticles have been designed and coated with a variety of silica morphologies and subsequently interrogated using extinction spectroscopy and SERS. It will be revealed that these gold nanoparticles entrapped in silica membranes serve as optically stable substrates for the quantitative and direct detection of target molecules. These advances in nanomaterial fabrication are envisioned to impact both fundamental and applied studies in a variety of research areas including catalysis, separations, and spectroscopy.
Research suggests that lesbian, gay and bisexual (LGB) adolescents have a higher risk of suicidal behaviours than their heterosexual peers, but little is known about specific risk factors.
To assess sexual orientation as a risk factor for suicidal behaviours, and to identify other risk factors among LGB adolescents and young adults.
A systematic search was made of six databases up to June 2015, including a grey literature search. Population-based longitudinal studies considering non-clinical populations aged 12–26 years and assessing being LGB as a risk factor for suicidal behaviour compared with being heterosexual, or evaluating risk factors for suicidal behaviour within LGB populations, were included. Random effect models were used in meta-analysis.
Sexual orientation was significantly associated with suicide attempts in adolescents and youths (OR=2.26, 95% CI 1.60–3.20). Gay or bisexual men were more likely to report suicide attempts compared with heterosexual men (OR=2.21, 95% CI 1.21–4.04). Based on two studies, a non-significant positive association was found between depression and suicide attempts in LGB groups.
Sexual orientation is associated with a higher risk of suicide attempt in young people. Further research is needed to assess completed suicide, and specific risk factors affecting the LGB population.
The improvement in porcine embryo preservation and non-surgical embryo transfer (ET) procedures achieved in recent years represents essential progress for the practical use of ET in the pig industry. This study aimed to evaluate the effects of parity, weaning-to-estrus interval (WEI) and season on reproductive and embryonic parameters at day 6 after insemination of donor sows superovulated after weaning. The selection of donor sows was based on their reproductive history, body condition and parity. The effects of parity at weaning (2 to 3, 4 to 5 or 6 to 7 litters), season (fall, winter and spring), and WEI (estrus within 3 to 4 days), and their interactions on the number of corpus luteum, cysts in sows with cysts, number and quality of viable and transferable embryos, embryo developmental stage and recovery and fertilization rates were evaluated using linear mixed effects models. The analyses showed a lack of significant effects of parity, season, WEI or their interactions on any of the reproductive and embryonic parameters examined. In conclusion, these results demonstrate that fertilization rates and numbers of viable and transferable embryos collected at day 6 of the cycle from superovulated donor sows are not affected by their parity, regardless of the time of the year (from fall to spring) and WEI (3 or 4 days).
First results from the 4-6 months observations of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The time series are evaluated in terms of solar irradiance variability, solar background noise characteristics and p-mode oscillations. The solar irradiance is modulated by the passage of active regions across the disk, but not all of the modulation is straightforwardly explained in terms of sunspot flux blocking and facular enhancement. The observed p-mode frequencies are more-or-less in agreement with earlier measurements, but it is interesting to note that systematic differences seem to exist between the observations in different colours. There is also evidence that magnetic activity plays a significant role in the dynamics of the oscillations beyond its modulation of the resonant frequencies. Moreover, by comparing the amplitudes of different components of p-mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation.
The European Union Network ANTENA started to work in October 1993. During these last three years, several collaborative projects have been undertaken. ANTENA has offered a very good opportunity for most of the European people doing asteroseismology to work together. The asteroseismological networks STEPHI and STACC have run within the framework of the project, obtaining fairly good results. New instrumentation has also been developed, such as the Four-Channel Stellar Photometer.
GOLF is designed to measure the Global Oscillations of the integrated solar disk, by determining the line-of-sight velocity of the photosphere as a function of time, over the frequency range 10−7 to 10−2 Hz.
The SOHO probe was successfully launched on December 2nd, 1995. The performances of the Atlas II flight, the trajectory and the final injection in the Halo orbit around the L1 Lagrangian point left on board a large amount of hydrazine, allowing the possibility for a mission extension later than the 2 planned years. The operations of the GOLF experiment started on January 16th for a period devoted to the initial tests and to the adjustments of the thermal settings. The effective solar observations started on February 18thand are still running. For the studies presented here below, the data set ends in mid-September. All tables and figures come from the compilation of the data analysis made in several institutes with different methods, and some complementary or additional results are displayed in the poster booklet published from this symposium.
This spatial experiment is under construction and has been defined as a 2 years mission on board SOHO, a satellite dedicated to the Sun which will be launched in mid 95. The main objectives are the detection of solar low degree acoustic modes and solar gravity modes for improving our knowledge of the solar nuclear region.
Increasing plant species diversity has been proposed as a means for enhancing annual pasture productivity and decreasing seasonal variability of pasture production facing more frequent drought scenarios due to climate change. Few studies have examined how botanical complexity of sown swards affects cow performance. A 2-year experiment was conducted to determine how sward botanical complexity, from a monoculture of ryegrass to multi-species swards (MSS) (grasses-legumes-forb), affect pasture chemical composition and nutritive value, pasture dry matter (DM) intake, milk production and milk solids production of grazing dairy cows. Five sward species: perennial ryegrass (L as Lolium), white clover and red clover (both referred to as T as Trifolium because they were always sown together), chicory (C as Cichorium) and tall fescue (F as Festuca) were assigned to four grazing treatments by combining one (L), three (LT), four (LTC) or five (LTCF) species. Hereafter, the LT swards are called mixed swards as a single combination of ryegrass and clovers, whereas LTC and LTCF swards are called MSS as a combination of at least four species from three botanical families. The experimental area (8.7 ha) was divided into four block replicates with a mineral nitrogen fertilisation of 75 kg N/ha per year for each treatment. In total, 13 grazing rotations were carried out by applying the same grazing calendar and the same pasture allowance of 19 kg DM/cow per day above 4 cm for all treatments. Clover represented 20% of DM for mixed and MSS swards; chicory represented 30% of DM for MSS and tall fescue represented 10% of DM for LTCF swards. Higher milk production (+1.1 kg/day) and milk solids production (+0.08 kg/day) were observed for mixed swards than for ryegrass swards. Pasture nutritive value and pasture DM intake were unaffected by the inclusion of clover. Pasture DM, organic matter and NDF concentrations were lower for MSS than for mixed swards. Higher milk production (+0.8 kg/day), milk solids production (+0.04 kg/day) and pasture DM intake (+1.5 kg DM/day) were observed for MSS than for mixed swards. These positive effects of MSS were observed for all seasons, but particularly during summer where chicory proportion was the highest. In conclusion, advantages of grazing MSS on cow performance were due to the cumulative effect of improved pasture nutritive value and increased pasture DM intake that raised milk production and milk solids production.
Pm-Si:H PIN and NIP solar cells structures grown using plasma enhanced chemical vapor deposition (PECVD) technique were analyzed during 400 hrs of light-soaking exposition. The evolution of the structural and optical properties was observed and characterized by Raman spectroscopy, spectroscopic ellipsometry. The effect observed is related to defects creation due to induced hydrogen diffusion, break of Si-H bonds and the generation of dangling bonds that causes less passivated films. The film microstructure, and therefore the optical properties varied with the exposition time. The crystalline fraction of these structures presents a slight decrease and it is observed to be between 15 to 24% for the PIN and 5 to 10% for the NIP. The optical gap increases from 1.66 to 1.68 eV for the PIN structure while for the NIP no significant change is observed during light-soaking. Hydrogen diffusion during lights soaking generates a decrease on the absorption properties of the films which in turn is expected to reduce the device efficiency during operation. In this work we show that long range motion of hydrogen during light-soaking causes a hydrogen rearrangement on the film and microstructure changes. We determined that there is not an pronounced change on the film structure during prolonged light exposition related to the stability of the pm-Si:H films. The PIN structure properties are more affected during light soaking in comparison to the NIP structure which is expected to cause less degradation of its optoelectronic properties under illumination, and a more stable device during operation.
We recently demonstrated that decline in fluid intelligence is a substantial contributor to frontal deficits. For some classical ‘executive’ tasks, such as the Wisconsin Card Sorting Test (WCST) and Verbal Fluency, frontal deficits were entirely explained by fluid intelligence. However, on a second set of frontal tasks, deficits remained even after statistically controlling for this factor. These tasks included tests of theory of mind and multitasking. As frontal dysfunction is the most frequent cognitive deficit observed in early Parkinson's disease (PD), the present study aimed to determine the role of fluid intelligence in such deficits.
We assessed patients with PD (n=32) and control subjects (n=22) with the aforementioned frontal tests and with a test of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate to determine its role in frontal deficits shown by PD patients.
In line with our previous results, scores on the WCST and Verbal Fluency were closely linked to fluid intelligence. Significant patient–control differences were eliminated or at least substantially reduced once fluid intelligence was introduced as a covariate. However, for tasks of theory of mind and multitasking, deficits remained even after fluid intelligence was statistically controlled.
The present results suggest that clinical assessment of neuropsychological deficits in PD should include tests of fluid intelligence, together with one or more specific tasks that allow for the assessment of residual frontal deficits associated with theory of mind and multitasking.
Aluminum-doped zinc oxide (ZnO:Al) thin films were prepared on glass substrates by radio frequency (RF) magnetron sputtering from a ceramic mixed target ZnO:Al2O3 (1 wt.%) with a power of 250 W. Two series of samples were deposited at room temperature, the first one in pure Ar atmosphere, the second one in Ar/O2 gas mixture. Effects of post-deposition annealing treatments carried out from 400 °C to 500 °C under vacuum and in N2/H2 (5%) atmosphere have been investigated. The influence of these parameters was studied by a detailed microstructural analysis using X-Ray diffraction and Raman spectroscopy. For N2/H2 annealing process, the increase of charge carrier concentration limits the increase of the mobility while after vacuum annealing, an improvement of both electrical and optical properties was observed. The increase of the crystallinity and grain size for ZnO:Al films deposited in Ar/O2 gas mixture could explain their improvements. Resistivity was reduced down to 3.5×10-4 Ω.cm, for a mobility of 49 cm2/V.s with a vacuum annealing at 450 °C for ZnO:Al deposited in Ar/O2 gas mixture.
The present work shows results on elemental distribution analyses in Cu(In,Ga)Se2 thin films for solar cells performed by use of wavelength-dispersive and energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope, EDX in a transmission electron microscope, X-ray photoelectron, angle-dependent soft X-ray emission, secondary ion-mass (SIMS), time-of-flight SIMS, sputtered neutral mass, glow-discharge optical emission and glow-discharge mass, Auger electron, and Rutherford backscattering spectrometry, by use of scanning Auger electron microscopy, Raman depth profiling, and Raman mapping, as well as by use of elastic recoil detection analysis, grazing-incidence X-ray and electron backscatter diffraction, and grazing-incidence X-ray fluorescence analysis. The Cu(In,Ga)Se2 thin films used for the present comparison were produced during the same identical deposition run and exhibit thicknesses of about 2 μm. The analysis techniques were compared with respect to their spatial and depth resolutions, measuring speeds, availabilities, and detection limits.
Amorphous silicon-based phototransistors are studied as an alternative solution to replace pixel-level amplifiers simplifying large-area imaging systems. We report electrical characterization by means of current-voltage and capacitance measurements. The measured capacitance increases with decreasing frequency of the probe signal and values largely exceeding the geometrical one at low frequencies have been achieved both in the dark and under illumination. In particular, values in excess of 200 μF/cm2 are measured under 220 μW/cm2 illumination at 600 nm at 100 mHz. The capacitance dependence on frequency is interpreted in terms of trapping and release kinetics processes in the base and of the gain of the device.
The contamination effects induced by B2H6 and B(CH3)3 in a-Si:H layers are compared, using in-situ Kelvin probe experiments as well as SIMS measurements. It is found that B(CH3)3 induces at least 50 times less contamination, even at 250°C. It is also found that materials containing CH3 radicals have a lower electron affinity.
Using a Kr ion laser (λ = 647.1 nm) to produce a carrier generation rate G of 3 × 1020 cm−3s−1, we have saturated the light-induced defect generation in hydrogenated (and fluorinated) amorphous silicon (a-Si:H(F)), within a few hours near room temperature. While the defect generation rate scales roughly with 1/G2, the saturation defect densities Ns,sat are essentially independent of G. The saturation is not due to thermal annealing. We have further measured Ns,sat m 37 a-Si:H(F) films grown in six different reactors under different conditions. The results show that Ns,sat lies between 5 × 1016 and 2 × 1017 cm−3, that Ns,sat drops with decreasing optical gap and hydrogen content, and that Ns,sat is not correlated with the initial defect density or with the Urbach energy.
The effect of the depletion region in amorphous silicon Schottky diodes on the mobility-deep trapping lifetime product μτ of electrons has been investigated using transient photoconductivity techniques. We varied the laser wavelength of the exciting laser in time-of-flight (TOF) measurements. The results are correlated with measurements of the internal field by means of the charge collection efficiency, and with measurement of the deep-trapping time by the Delayed-Field TOF technique (DFTOF). We find that the electron μτ decreases from the bulk toward the top surface.
We report the effect of thermal equilibration on the dark- and photo- conductivities of an un-doped a-Si,Ge:H,F with optical gap of 1.47 eV. Annealing at high temperature and subsequent quenching can freeze in the equilibrium configuration at the annealing temperature. The characteristic glass-like transition behavior of the conductivities was observed and used to estimate a freeze-in temperature of about 140°C. As the annealing temperature increases above the freeze-in temperature, the frozen-in dark- and photo- conductivities decrease, the photo- to dark- conductivity ratio increases, and the photoconductivity-generation rate exponent increases. These changes in conductivities are explained by a model calculation, which assumes that the quenching introduces new defect states to die lower energy flanks of the Gaussian defect distributions.
The thickness dependence of the sub-gap optical absorption in plasma-deposited hydrogenated amorphous silicon is carefully studied by photo-thermal deflection spectroscopy. The deep-level defect concentration decays from the top surface into the bulk where it approaches the thermal equilibrium defect density. This defect profile is interpreted in terms of the annealing, during growth, of growth-induced surface defects. It is also shown that the defect profile is compatible with the known growth-temperature dependence of the average defect density in amorphous silicon.