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This work reports the fabrication and characterization of superstrate-type Zn1-xMgxO/CdTe heterojunction solar cells on both CdxSnyO and commercial SnO2:F transparent conducting oxides (TCOs) in which the ZMO and CTO layers are produced for the first time by hollow cathode sputtering. The sputtering is conducted in a reactive mode using metal or alloyed metal targets fitted to a custom-made linear cathode. It is notable that the CdS buffer layer conventionally employed in CdTe solar cells is entirely replaced by the ZMO window layer. The use of ZMO is found to eliminate the blue loss associated with CdS optical absorption and further results in a higher open-circuit voltage. Key parameters were found to be the conduction band offset at the ZMO/CdTe interface and the ZMO thickness. It was discovered that the ZMO exhibits intense photoluminescence even at room temperature. Most of the solar cells were fabricated in the FTO/ZMO/CdTe configuration although CTO/ZMO/CdTe solar cells were also demonstrated. The CTO was produced with an electron mobility of 46 cm2 V-1s-1 without any post-deposition annealing or treatment.
There is inconsistent evidence regarding the influence of general
cognitive abilities on the long-term course of depression.
To investigate the association between general childhood cognitive
abilities and adult depression outcomes.
We conducted a cohort study using data from 633 participants in the New
England Family Study with lifetime depression. Cognitive abilities at age
7 were measured using the Wechsler Intelligence Scale for Children.
Depression outcomes were assessed using structured diagnostic interviews
administered up to four times in adulthood between ages 17 and 49.
In analyses adjusting for demographic factors and parental psychiatric
illness, low general cognitive ability (i.e. IQ<85 v.
IQ>115) was associated with recurrent depressive episodes (odds ratio
(OR) = 2.19, 95% CI 1.20–4.00), longer episode duration (rate ratio 4.21,
95% CI 2.24–7.94), admission to hospital for depression (OR = 3.65, 95%
CI 1.34–9.93) and suicide ideation (OR = 3.79, 95% CI 1.79–8.02) and
attempt (OR = 4.94, 95% CI 1.67–14.55).
Variation in cognitive abilities, predominantly within the normal range
and established early in childhood, may confer long-term vulnerability
for prolonged and severe depression. The mechanisms underlying this
vulnerability need to be established to improve the prognosis of
depression among individuals with lower cognitive abilities.
We examined developmental programming studies that reported sex-specific effects published between 2012 and 2014, and examined whether the authors reported a statistical approach to explicitly test whether the effect of treatment differed between the sexes, for example, a sex by treatment interaction term. Less than half of the studies that reported sex-specific effects described explicitly testing whether effects were indeed sex-specific; in most cases, an effect was considered ‘sex-specific’ if it was significant in one sex but not the other. This is not a robust approach, since significance in one sex and lack of significance in the other sex does not imply a significant difference between the sexes. However, sample size often limits statistical power to detect interactions. We suggest that if the effect is significant in only one sex, but the interaction term is not significant, alternative solutions would be to present the confidence intervals for the effect size for each sex, or using Bayesian approaches to calculate the probability that the effect sizes differ between the sexes. We present a simple example of a Bayesian analysis to illustrate that this approach is reasonably easy to implement and interpret.
Here we report our study of the electronic properties of -textured gadolinium nitride (GdN) thin films synthesized using a chemical vapor deposition (CVD) method. The electronic properties of the films were investigated using photoemission and inverse photoemission spectroscopy coupled with computational modeling. Our density functional theory (DFT) calculations suggest that the theoretically predicted half-metallic electronic structure of GdN is likely due to its low density of states (DOS) at the Fermi level. These calculations are supported by our photoemission and inverse photoemission spectroscopic measurements which show a band gap for the prepared films of a few milli-electron volts, seemingly consistent with the predicted electronic structure. Additionally, the use of a CVD gallium nitride capping layer was found to decelerate the surface oxidation of our GdN samples.
Correlating patient perception of nasal obstruction sidedness to causative anatomy is important in surgical planning. The accuracy of patient-perceived asymmetry of nasal obstruction, as regards objective measures, is described.
Cross-sectional study of patients undergoing nasal airflow assessment. Unilateral obstruction was assessed using visual analogue scale scores and anterior rhinomanometry, without decongestion. Subjective obstruction asymmetry was defined using either the absolute score difference (right vs left) or the minimal clinically important difference, derived statistically. Correlation between subjective and objective obstruction measures was assessed.
In 145 patients (mean age ± standard deviation, 42.8 ± 16.6 years; 54.5 per cent female), objective obstruction was right-sided in 32.4 per cent, left-sided in 36.6 per cent and symmetrical in 31.0 per cent. Subjective perception of obstruction sidedness had a sensitivity and specificity of 86.9 and 41.1 per cent, respectively, using the minimal clinically important difference. Positive predictive value was 59.4 per cent using absolute score difference and 53.7 per cent using minimal clinically important difference. Receiver operator characteristic curve analysis indicated correlation between subjective and objective measures (p < 0.001).
Subjective perception of nasal obstruction asymmetry has limited accuracy. Corroboration with objective airway assessment may be helpful in patients whose symptoms are incongruous with clinical findings.
School mobility has been shown to increase the risk of poor achievement, behavior problems, grade retention, and high school dropout. Using data over 25 years from the Chicago Longitudinal Study, we investigated the unique risk of school moves on a variety of young adult outcomes including educational attainment, occupational prestige, depression symptoms, and criminal arrests. We also investigated how the timing of school mobility, whether earlier or later in the academic career, may differentially predict these outcomes over and above associated risks. Results indicate that students who experience more school changes between kindergarten and 12th grade are less likely to complete high school on time, complete fewer years of school, attain lower levels of occupational prestige, experience more symptoms of depression, and are more likely to be arrested as adults. Furthermore, the number of school moves predicted outcomes above and beyond associated risks such as residential mobility and family poverty. When timing of school mobility was examined, results indicated more negative outcomes associated with moves later in the grade school career, particularly between 4th and 8th grades.
3D integration enabled by through-silicon-via (TSV) allows continued performance enhancement and power reduction for semiconductor devices, even without further scaling. For TSV wafers with all Applied Materials unit processes, we evaluate the integrity of oxide liner and copper barrier by capacitance-voltage (C-V) and current-voltage (I-V) measurements, from which oxide capacitance, minimum TSV capacitance, and leakage current are extracted. The capacitance values match well with model predictions. The leakage data also demonstrate good wafer-scale uniformity. The liner and barrier quality are further verified with microanalysis techniques.
For CdTe there is no real distinction between defects and impurities exists when non-shallow dopants are used. These dopants act as beneficial impurities or detrimental carrier trapping centers. Unlike Si, the common assumption that the trap energy level Et is around the middle of the band-gap Ei, is not valid for thin film CdTe. Trap energy levels in CdTe band-gap can distributed with wide range of energy levels above EF. To identify the real role of traps and dopants that limit the solar cell efficiency, a series of samples were investigated in thin film n+-CdS/p-CdTe solar cell, made with evaporated Cu as a primary back contact. It is well known that process temperatures and defect distribution are highly related. This work investigates these shallow level impurities by using temperature dependent current-voltage (I-V-T) and temperature dependent capacitance-voltage (C-V-T) measurements. I-V-T and C-V-T measurements indicate that a large concentration of defects is located in the depletion region. It further suggests that while modest amounts of Cu enhance the cell performance by improving the back contact to CdTe, the high temperature (greater than ∼100°C) process condition degrade device quality and reduce the solar cell efficiency. This is possibly because of the well-established Cu diffusion from the back contact into CdTe. Hence, measurements were performed at lower temperatures (T = 150K to 350K). The observed traps are due to the thermal ionization of impurity centers located in the depletion region of p-CdTe/n+-CdS junction. For our n+-CdS/p-CdTe thin film solar cells, hole traps were observed that are verified by both the measurement techniques. These levels are identical to the observed trap levels by other characterization techniques.
NGC 1097 is a nearby barred spiral galaxy believed to be interacting with the elliptical galaxy NGC 1097A located to its northwest. It hosts a Seyfert 1 nucleus surrounded by a circumnuclear starburst ring. Two straight dust lanes connected to the ring extend almost continuously out to the bar. The other ends of the dust lanes attach to two main spiral arms. To provide a physical understanding of its structural and kinematical properties, two-dimensional hydrodynamical simulations have been carried out. Numerical calculations reveal that many features of the gas morphology and kinematics can be reproduced provided that the gas flow is governed by a gravitational potential associated with a slowly rotating strong bar. By including the self-gravity of the gas disk in our calculation, we have found the starburst ring to be gravitationally unstable which is consistent with the observation in Hsieh et al. (2011). Our simulations also show that gas can flow into the region within the starburst ring even after its formation, leading to the coexistence of both a nuclear ring and a circumnuclear disk.
The present study aims to determine the optimum radio frequency (RF) sputtering power to obtain the desired W–TiO2 nanotubes for the best photoelectrochemical (PEC) performance. Tungsten (W) was deposited on titania (TiO2) nanotube arrays via RF sputtering technique under different sputtering powers from 50 to 250 W. The optimum content of W on TiO2 nanotube arrays play a significant role in maximizing the photocurrent generation efficiency to promote charge separation by accumulation of photogenerated electrons. The sputtering power below 180 W exhibited high-ordered and unbroken TiO2 nanotube arrays. However, the sputtering power over 180 W exhibited broken nanotube arrays and an oxide layer was formed due to the impact of high energy ions accelerated by a high sputtering power. The TiO2 nanotube arrays sputtered with tungsten at 50 W showed a better photocurrent density (1.55 mA/cm2), with a photoconversion efficiency of 2.2% in the PEC performance among the samples due to the effective charge separation and reduced recombination center in the resultant W–TiO2 nanotubes.
The effect of race on cognitive test performance in the evaluation of Alzheimer's disease (AD) remains controversial. One factor that may contribute substantially to differences in cognitive test performance in diverse populations is education. The current study examined the extent to which quality of education, even after controlling for formal years of education, accounts for differences in cognitive performance between African Americans and White Non-Hispanics (WNHs). The retrospective cohort included 244 patients diagnosed with AD who self-identified as African Americans (n = 51) or WNHs (n = 193). The Wechsler Test of Adult Reading (WTAR) was used as an estimate of quality of education. In an analysis that controlled for traditional demographics, including age, sex, and years of formal education, African Americans scored significantly lower than WNHs on the Mini-Mental State Examination, as well as on neuropsychological tests of memory, attention, and language. However, after also adjusting for reading level, all previously observed differences were significantly attenuated. The attenuating effect remained even after controlling for disease severity, indicating that reading scores are not confounded by severity of dementia. These findings suggest that quality, and not just quantity, of education needs to be taken into account when assessing cognitive performance in African Americans with AD. (JINS, 2012, 18, 277–285)
To investigate the association of antioxidant intakes from diet and supplements with elevated blood C-reactive protein (CRP) and homocysteine (Hcy) concentrations.
A cross-sectional study. The main exposures were vitamins C and E, carotene, flavonoid and Se intakes from diet and supplements. Elevated blood CRP and Hcy concentrations were the outcome measures.
The US population and its subgroups.
We included 8335 US adults aged ≥19 years from the National Health and Nutrition Examination Survey 1999–2002.
In this US population, the mean serum CRP concentration was 4·14 (95 % CI 3·91, 4·37) mg/l. Intakes of vitamins C and E and carotene were inversely associated with the probability of having serum CRP concentrations >3 mg/l in multivariate logistic regression models. Flavonoid and Se intakes were not associated with the odds of elevated serum CRP concentrations. The mean plasma Hcy concentration was 8·61 (95 % CI 8·48, 8·74) μmol/l. Intakes of vitamins C, E, carotenes and Se were inversely associated with the odds of plasma Hcy concentrations >13 μmol/l after adjusting for covariates. Flavonoid intake was not associated with the chance of elevated plasma Hcy concentrations.
These results suggest that high antioxidant intake is associated with lower blood concentrations of CRP and Hcy. These inverse associations may be among the potential mechanisms for the beneficial effect of antioxidant intake on CVD risk mediators in observational studies.
Methods for extracting or harvesting energy from the surrounding battlefield environment are of great importance to the United States Army. Scavenging energy from local environments reduces the required energy and weight transported to the theater. Micro- and nano-scale metal-insulator-metal (MIM) tunnel diodes are being developed to provide half-wave rectification as part of a “rectenna” energy harvesting system, which includes a radiation-collecting antenna, a rectifying MIM tunnel diode, and a storage capacitor. In this work, high-frequency MIM tunnel diodes for power rectification were designed, fabricated and characterized. Planar Pt/TiO2/Ti stacks are being fabricated to create a diode with highly asymmetric I-V characteristics that has a very low threshold voltage. The metals were chosen for their high work function difference, and the insulator was chosen for its barrier height, its compatibility with Ti, and its availability. The energy band diagram and the I-V characteristics were modeled to determine the feasibility of the Pt/TiO2/Ti material system for use as a rectifier diode in a rectenna system. Metals and insulator thin films were deposited onto silicon dioxide/silicon substrates. Pillars with lateral dimensions ranging from 20 μm x 20 μm up to 100 μm x 100 μm were fabricated. The dielectric thickness of the MIM diode was varied from 5 nm up to 50 nm to determine the optimal thickness for quantum tunneling. I-V measurements were taken using an electrical characterization system to confirm a non-linear, asymmetric response on a survey of devices fabricated with varying areas. Preliminary results exhibit asymmetric I-V characteristics with threshold voltages of less than 700 mV.
Our previous studies demonstrated prompt elevation of proteinase activity in mammary secretion of drying-off cows and goats. The current study examined the progressive changes in composition of cow mammary secretion following drying-off and, in parallel, characterized the mode of peptide neogenesis using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography-electrospray-ionization (LC-ESI) MS/MS. The results show that the percentage of casein of total milk protein at time of drying-off was 76%, which dropped to 41%, 24%, and 16%, respectively, 1, 2, and 3 weeks after drying-off. Levels of β-lactoglobulin and α-lactoalbumin in mammary secretions of drying-off cows decreased prominently while levels of lactoferrin, BSA, and casein derived-proteins increased concomitantly compared with regular milk. A fractionation procedure was applied to remove molecules larger than 10 kDa before MALDI-TOF MS and LC-ESI MS/MS and the results show that the MALDI-TOF MS peptide profile of mammary secretion ranging from m/z 600 to 4000 was apparently modified after drying-off for 1 week, whereas species 1590 m/z and 2460 m/z were most obviously enriched compared with regular milk. LC-ESI MS/MS results were used to map peptide sequence with Mascot search server and under no post translational modification to reduce database size and 202 novel β-casein-derived peptides were successfully identified in mammary secretion after drying-off for 1 week in contrast to regular milk. Accordingly at least 48 additional cleavage positions were assigned on β-casein for mammary secretion. Among the 202 novel peptides, 5 are homologous with confirmed opioid agonists, angiotensin 1-converting enzyme inhibitors, or immuno-modulators. In conclusion, peptides are released in situ from milk proteins within short intervals following drying-off in cows. They might play roles in the transition of mammary glands from lactating to non-lactating. With specified post-translational modifications and focused functional screening, novel peptides are yet to be discovered in dry cow mammary secretion.
Phosphorus is an important n-type dopant for both silicon and silicon carbide. Although solid-state diffusion of phosphorus in silicon has been well documented and experimentally proven, not much is known about phosphorus solid-state diffusion in silicon carbide, especially at lower temperatures. A convenient source of phosphorus for solid-state diffusion in silicon carbide is phosphorus oxide. The possibility of using phosphorus oxide as a dopant source for silicon carbide is investigated by considering the probable reactions between silicon carbide and phosphorus oxide at temperatures below 1700 K using published thermodynamic data. By considering the standard free energies of reactions, it can be shown that phosphorus can be introduced in silicon carbide at temperatures below 1700 K using phosphorus oxide. A successful development of low temperature dopant incorporation in silicon carbide would reduce the need for high temperature processes and prevent process-induced thermal degradation of critical device structures such as the oxide-semiconductor interface. Experimental results showing phosphorus impurity incorporation and activation in 4H-SiC are presented.