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Cognitive impairment is a core feature of major depressive disorder (MDD). Cognitive remediation may improve cognition in MDD, yet so far, the underlying neural mechanisms are unclear. This study investigated changes in intrinsic neural activity in MDD after a cognitive remediation trial.
In a longitudinal design, 20 patients with MDD and pronounced cognitive deficits and 18 healthy controls (HC) were examined using resting-state functional magnetic resonance imaging. MDD patients received structured cognitive remediation therapy (CRT) over 5 weeks. The whole-brain fractional amplitude of low-frequency fluctuations was computed before the first and after the last training session. Univariate methods were used to address regionally-specific effects, and a multivariate data analysis strategy was employed to investigate functional network strength (FNS).
MDD patients significantly improved in cognitive function after CRT. Baseline comparisons revealed increased right caudate activity and reduced activity in the left frontal cortex, parietal lobule, insula, and precuneus in MDD compared to HC. In patients, reduced FNS was found in a bilateral prefrontal system at baseline (p < 0.05, uncorrected). In MDD, intrinsic neural activity increased in right inferior frontal gyrus after CRT (p < 0.05, small volume corrected). Left inferior parietal lobule, left insula, left precuneus, and right caudate activity showed associations with cognitive improvement (p < 0.05, uncorrected). Prefrontal network strength increased in patients after CRT, but this increase was not associated with improved cognitive performance.
Our findings support the role of intrinsic neural activity of the prefrontal cortex as a possible mediator of cognitive improvement following CRT in MDD.
Dietary carbohydrates constitute a major fraction of the diets for pigs. The carbohydrate fraction consists of mono-, di- and oligosaccharides and two broad classes of polysaccharides – starch and non-starch polysaccharides (NSP). The carbohydrate fraction has a diverse composition in terms of constituent sugars (pentoses, hexoses, deoxysugars, etc.), glycosidic linkages (alfa or beta), size (degree of polymerisation from one to several thousand), and physical form (soluble in water, insoluble, cation and adsorbing properties). It is now evidential clear that the composition of the carbohydrate fraction influences the digestion and absorption processes of carbohydrates and other nutrients in the various parts of the gastrointestinal tract, it has a profound influence on the secretory response of the gut to feed intake, the volume flow, the mucosal architecture, the composition of the gut flora and the development of the gastrointestinal tract.
The IRAM interferometer has been used to image the distribution and kinematics of the HCO+ line in the nuclear region of IC 342 and of the HCN line in the nuclear region of Maffei2. Both regions were also imaged in the continuum at 3mm. These observations are compared with observations of HCN in IC 342 and CO in both galaxies.
The effects of a high level of dietary fibre (DF) either as arabinoxylan (AX) or resistant starch (RS) on digestion processes, SCFA concentration and pool size in various intestinal segments and on the microbial composition in the faeces were studied in a model experiment with pigs. A total of thirty female pigs (body weight 63·1 (sem 4·4) kg) were fed a low-DF, high-fat Western-style control diet (WSD), an AX-rich diet (AXD) or a RS-rich diet (RSD) for 3 weeks. Diet significantly affected the digestibility of DM, protein, fat, NSP and NSP components, and the arabinose:xylose ratio, as well as the disappearance of NSP and AX in the large intestine. RS was mainly digested in the caecum. AX was digested at a slower rate than RS. The digesta from AXD-fed pigs passed from the ileum to the distal colon more than twice as fast as those from WSD-fed pigs, with those from RSD-fed pigs being intermediate (P< 0·001). AXD feeding resulted in a higher number of Faecalibacterium prausnitzii, Roseburia intestinalis, Blautia coccoides–Eubacterium rectale, Bifidobacterium spp. and Lactobacillus spp. in the faeces sampled at week 3 of the experimental period (P< 0·05). In the caecum, proximal and mid colon, AXD feeding resulted in a 3- to 5-fold higher pool size of butyrate compared with WSD feeding, with the RSD being intermediate (P <0·001). In conclusion, the RSD and AXD differently affected digestion processes compared with the WSD, and the AXD most efficiently shifted the microbial composition towards butyrogenic species in the faeces and increased the large-intestinal butyrate pool size.
CuInS2 (CIS) films were prepared by chemical spray pyrolysis (CSP) method in air using CuCl2, InCl3 and SC(NH2)2 as precursor materials. The effect of the absorber growth temperature in the interval of 240-350 °C and precursors’ molar ratio in the spray solution on the CIS film properties and ZnO/In2S3/CIS-type CSP-deposited thin film solar cell output characteristics has been studied. CIS films were characterized by XRD and EDX, solar cells were characterized by IV curves in dark and under illumination, and junction barrier height (Φb). The highest Φb of 1170 meV and open circuit voltage (Voc) of 560 mV were recorded for the cell with CIS absorber grown at 250 °C. Increasing the CIS deposition temperature decreases Φb and Voc, makes a component of solar cell photosensitive and increases current density. The precursors’ molar ratio in spray solution becomes relevant at CIS growth temperatures higher than 300 °C as deposition of thiourea-rich solutions suppresses oxide formation in CIS layer and contributes to higher open circuit voltage.
It has been demonstrated in literature that chemical liquid deposition (CLD) processes such as dip coating, spray coating, roll coating, spin coating, curtain coating, meniscus coating etc. can be successfully used to deposit anti-reflective coatings on glass substrates. In comparison to physical vapor deposition (PVD), a CLD process generally is cost efficient because of lower capital requirements to set up coating manufacturing lines. Within the realm of CLD processes only some application techniques are suitable for high speed continuous manufacturing processes to deposit coatings on large area glass substrates. Significant differences in transfer efficiencies of these high speed application processes are readily apparent when material utilization per unit area of glass are compared. Roll coat process among all the high speed CLD processes stands out for its high material transfer efficiency due to direct contact printing on flat glass substrates. Honeywell Electronic Materials expanded its line of SOLARC® anti-reflective coating materials to include a new coating formulation SOLARC® RPV, which is customized for roll coating application. This paper highlights the advantages of using SOLARC® RPV in roll coat process and the performance attributes of SOLARC® anti-reflective coatings. Durability characteristics of these anti-reflective coatings in accelerated aging tests designed to simulate harsh field conditions will also be discussed.
Pyrite phase of FeS2 has attracted substantial attention in the field of thin film solar technology because of its high optical absorption coefficient (~5 x 105 cm-1 at hν > 1.3eV) and the band gap of 0.95 eV. In this research, we have grown highly pure iron pyrite films using a low temperature atmospheric pressure chemical vapor deposition technique. The synthesis temperature is in the range of 375-400°C and Di-tert-butyl disulfide (TBDS) is used as the sulfur precursor. TBDS is a safe and low cost sulfur source unlike H2S, which is highly toxic and requires extreme care in handling. The films obtained were uniform and free from common impurity phases such as troilite and marcasite. The FeS2 films grown earlier with CVD synthesis and sulfurized using H2S had pinholes and contained secondary phases like marcasite and troilite. The FeS2 pyrite phase was confirmed using various characterization techniques that included SEM, EDS, XRD and XPS.
While the global market for photovoltaic (PV) modules continues to grow 30% - 40% annually, manufacturers are looking at advanced technologies and cell concepts in order to improve the cost performance and reliability. One of the challenges faced by the silicon (Si) PV manufacturers is the lack of efficient metal screen-printing technologies. While screen-printing is a long-established technology, THE traditional silver-based pastes have technical limits in terms of paste composition, drying and thermal-firing conditions, line-width, aspect ratio, contact resistance, etc. Such limits keep the industrial cell structure from being close to an ideal PV cell architecture. In an effort to develop alternate printable pastes electrically, electrically conductive adhesives are considered in this study to provide fine-line contacts and low thermal budget so that performance-driven solar cell designs can be reliably implemented in manufacturing. Mechanical properties of solar cell printed by conductive adhesives are experimentally investigated in this work and confirmed with the simulation results.
CdTe and CdS are emerging as the most promising materials for thin film photovoltaics in the quest of the achievement of grid parity. The major challenge for the advancement of grid parity is the achievement of high quality at the same time as low fabrication cost. The present paper reports the results of the new deposition technique, Pulsed Plasma Deposition (PPD), for the growth of the CdTe layers on CdS/ZnO/quartz and quartz substrates. The PPD method allows to deposit at low temperature. The optical band gap of deposited layers is 1.50 eV, in perfect accord with the value reported in the literature for the crystalline cubic phase of the CdTe.
The films are highly crystalline with a predominant cubic phase, a random orientation of the grains of the film and have an extremely low surface roughness of 4.6±0.7 nm r.m.s.. The low roughness, compared to traditional thermal deposition methods (close space sublimation and vapour transport) permits the reduction of the active absorber and n-type semiconductor layers resulting in a dramatic reduction of material usage and the relative deposition issues like safety, deposition rate and ultimately cost
In the past two decades, the growing global demand for solar energy has spurred scientific interest in alternative technologies to conventional silicon. In particular, CuIn1-xGaxSe2 (CIGS) has emerged as a competitor. We have developed a scalable deposition technique using RF magnetron sputtering of quaternary CIGS. Notably, the resulting films do not require postselenization, reducing processing time and cost. We have fabricated devices above 10% efficiency using this approach, showing its promise as a production method for highperformance CIGS photovoltaics. However, the morphology of the sputtered CIGS layer is markedly different from conventional evaporated films; grain sizes vary through the thickness of the film, with numerous small grains dominating at the Mo/CIGS interface that then either terminate or grow in an inverted-pyramid fashion to form large, columnar grains at the CIGS/CdS interface.
To better understand the origin of this morphology, we have studied the growth behavior of the CIGS layer using a combination of atomic force microscopy and electron microscopy to observe initial nucleation and grain growth behavior of quaternary-sputtered CIGS. We also discuss the effects of interfacial layers at the Mo/CIGS interface, demonstrating a novel wetting layer that conformally coats the Mo surface.
A low-resistance back contact for n-CdS/p-CdTe solar cells has been developed, which utilizes a thermally evaporated MoOx thin film as the buffer layer between the p-CdTe and the back electrode. The low-resistance behavior of back contact is attributed to the high work function of MoOx, which reportedly is as high as 6.8 eV, and thus adequately matches that of p-CdTe. With MoOx as the buffer, a variety of common metals, even those with a low work function such as Al, have been found to be useful as the electrode in forming the back contact. Other advantages of the MoOx buffer include dry application by vacuum deposition, and thus it is particularly suitable for the fabrication of ultra-thin CdTe solar cells without introducing additional shorting defects. Surface cleaning of CdTe films prior to MoOx deposition has also been studied. The cell stability has been evaluated through thermal annealing tests. Thermal degradation has been explained in terms of oxidation of the metal electrodes. CdTe cells with high efficiency and good stability have been demonstrated with MoOx as the back contact buffer and Ni as the electrode.
In this study indium tin oxide (ITO) thin films have been deposited by RF sputtering technique on quartz substrate. In all cases, the substrate was heated during deposition. Thin film deposited under various process conditions, shows characteristic XRD reflection corresponding to the (222) crystal orientation. Transmittance of the film has been measured for the wavelength range from 190 to 3300 nm. Average transmittance of 84.4%, 90.2% and 85.3% for wavelengths up to 800 nm, 2500 nm and 3300 nm respectively has been obtained. The resistivity in this case is found to be as low as ∼10 × 10-4 Ω-cm. Our study is focused on controlling the resistivity of the deposited film, without compromising transmittance in the near infra red (NIR) region of the spectrum. Substrate heating during deposition is found to result in films with grains which are oriented in (222) direction predominantly. Moreover, the average grain size is increased with subsequent annealing. It has been observed that though the transmittance for the samples doesn’t vary substantially upon annealing the resistivity decreases by several factors.
The solar cells employed in low to medium (50 to 200 suns) concentration photovoltaic (CPV) are usually mono-crystalline silicon. Laser Groove Buried Contacts (LGBC) are preferred to screen printing in these cells due to the high currents generated in the system. In this paper, we report on the use of Coherence Correlation Interferometry (CCI) to accurately measure the width and depth of the laser-ablated grooves. In addition, the technique is also used to measure the surface roughness at the bottom of the trenches, since this can determine the success of the subsequent plating process, and at the top surface to optimize the debris control and obtain clean surfaces and well-shaped groove edges. The laser ablation process was also optimized to obtain the groove aspect ratio and surface quality required. Process parameters to be controlled include laser power, pulse energy, stage speed and focal length. The CCI technique is capable of providing all the groove and surface metrology required for this process optimization.
To understand paths towards higher efficiency (η) for copper-indium-gallium-(sulfur)-selenide [CIG(S)Se] solar cells, we investigated a variety of absorber composition grading schemes for various back-side gallium (Ga), front-side sulfur (S), and double-graded Ga composition depth profiles in TCAD 1D/2D simulations. We fitted experimental results of a Back-Side Graded (BSG) solar cell with our TCAD models, prior to investigating other grading and interface schemes. The BSG solar cell was fabricated on a High Productivity Combinatorial (HPC™) platform based on sputtering Cu(In,Ga) followed by selenization. Our TCAD simulation methodology for optimizing CIG(S)Se solar cells started with a sensitivity analysis using 1D Solar-cell CAPacitance Simulator (SCAPS)  by selecting a typical range of key model parameters and analyzing the impact on η. We then used a 2D commercially-available Sentaurus simulation tool  to incorporate wavelength-dependent optical characteristics. As a result, we provide insight in the impact of grading schemes on efficiency for a fixed ‘material quality’ equal to an in-house BSG solar cell. We also quantify the effects of interface layers like MoSe2 at the Mo/CIG(S)Se interface, and an inverted surface layer at the CIG(S)Se/CdS interface.
In this paper the effect of Si1-xGex absorber layer thickness on thin film a-Si:H/crystalline-Si1-xGex/c-Si heterojunction solar cells (HIT cells) is studied by simulation and experiment. Cells with 1, 2 and 4 μm-thick epitaxial cap layers of p-type Si0.59Ge0.41 on top of 5 μm Si1-xGex graded buffer layers are fabricated and compared to study the effect of the absorber layer thickness. The results show no change in Voc (0.41V) and that Jsc increases from 17.2 to 18.1 mA/cm2 when the Si0.59Ge0.41 absorber layer thickness is increased from 1 to 4 μm. The effect of thickness on Jsc is also observed for 2 and 4 μm-thick Si and Si0.75Ge0.25 absorber layers. Experiments and simulations show that larger Ge fractions result in a higher magnitude and smaller thickness dependence of Jsc, due to the larger absorption coefficient that increases optical carrier generation in the near surface region for larger Ge contents.
We report CdTe/CdS solar cell with CdTe layer grown by sputtering method. A controlled etch and anneal process on the sputter-grown CdTe films was performed to increase the average grain size of the film. The process involved dipping the CdTe films in a saturated solution of cadmium chloride (CdCl2) in methanol (2.08 gram in 100 ml) followed by a 30 minute annealing at 400 °C. We performed various experiments on this process by varying the dipping times, drying process and annealing times and analyzed the resultant films using Scanning Electron Microscopy (SEM). We could see a clear increase in grain size from 200 nm to 5 μm after CdCl2 treatment. The process also increased the overall roughness of the sample so that more light is absorbed than reflected. We prepared solar cells using CdTe as p-type layer and CdS as n-type layer. The efficiency of the cell improved from 1.1% to 4.2% after air annealing. The effect of air-annealing is studied by means of quantum efficiency measurement.
In the present work we report the synthesis of Cu2ZnSnS4 (CZTS) films by pulsed laser deposition (PLD) and the effect of sulfur annealing on structure, composition, morphological and optical characterization of CZTS thin films. Raman spectra of the films exhibited the characteristics peaks of Kesterite structure. However, annealing caused to transfer the films from amorphous state into crystalline state. Scanning electron microscope (SEM) images revealed that as-deposited film exhibited a crack free, smooth, densely packed and homogeneous surface which was changed to rigid granular appearance after annealing. Energy dispersive X-ray spectroscopy (EDS) determined the compositions of the CZTS thin films which was near stoichiometry for the annealed samples. Ultraviolet–visible (UV–Vis) spectra showed the band gap of as-deposited film was 1.60 eV which was decreased to 1.40 eV after annealing.
A primary challenge to the industrial uptake of dye-sensitized solar cells (DSC) is the ability to improve manufacturing efficiency. New thinking is required in terms of lowering cost, improving the process steps and increasing throughput. The typical manufacture of a DSC contains a number of long process steps; the sintering and dyeing of the TiO2 are prime examples. The current solution is to batch process on rigid substrates or use long energy intensive convection ovens for flexible metal substrates. Here we present a method for reducing some of the bottlenecks in the manufacturing process using near infra red radiation to speed up the thermal treatment of TiO2 and silver inks reducing their processing times to 12 and 2 seconds from normal process times of 30 and 10 minutes respectively.