Nighttime Sleep Awakening Frequency and Its Consistency Predict Future Academic Performance in College Students

Although the relationship between sleep and academic performance has been extensively examined, how sleep predicts future academic performance (e.g., 2-3 years) remains to be further investigated. Using wearable smartwatches and a self-report questionnaire, we tracked sleep activities of 45 college students over a period of approximately half a month to see whether their sleep activities predicted their academic performance, which was estimated by grade point average (GPA). Results showed that both nighttime sleep awakening frequency and its consistency in the tracking period were not significantly correlated with the GPA for the courses taken in the sleep tracking semester (current GPA). However, both nighttime sleep awakening frequency and its consistency inversely predicted the GPA for the rest of the courses taken after that semester (future GPA). Moreover, students with more difficulty staying awake throughout the day obtained lower current and future GPAs, and students with higher inconsistency of sleep quality obtained lower future GPA. Together, these findings highlight the importance of nighttime sleep awakening frequency and consistency in predicting future academic performance, and emphasize the necessity of assessing the consistency of sleep measures in future studies.

Sex differences in hemispheric lateralization of attentional networks

Males and females differ in various abilities. However, sex differences in hemispheric lateralization of attentional processing are still not well-understood. Using a lateralized version of the attentional network test that combines the Posner cueing paradigm and visual field methodology, we aimed to examine sex differences in the lateralization of several attentional processes including alerting, executive control, orienting benefit, reorienting, and orienting cost. Fifty-six females and 59 males participated in this study. We found a left visual field (right hemisphere) advantage for alerting defined by the differences between no-cue and center-cue conditions in the male group, but it was mainly attributed to the left visual field advantage in the no-cue condition. In contrast, the female group exhibited a left visual field advantage in the center-cue condition. Both groups showed preferences to the left visual field for reorienting and orienting cost, but females exhibited larger effects. This indicates that the two sexes exhibit similarities in terms of the lateralization of these two attentional processes. Furthermore, the interactions between executive control and reorienting/orienting cost were more efficient in males than in females. The current study highlights sex differences in the hemispheric lateralization of attentional networks and possible underlying neural substrates.

Autonomous atmospheric water seeping MOF matrix

The atmosphere contains an abundance of fresh water, but this resource has yet to be harvested efficiently. To date, passive atmospheric water sorbents have required a desorption step that relies on steady solar irradiation. Since the availability and intensity of solar radiation vary, these limit on-demand desorption and hence the amount of harvestable water. Here, we report a polymer-metal-organic framework that provides simultaneous and uninterrupted sorption and release of atmospheric water. The adaptable nature of the hydro-active polymer, and its hybridization with a metal-organic framework, enables enhanced sorption kinetics, water uptake, and spontaneous water oozing. We demonstrate continuous water delivery for 1440 hours, producing 6 g of fresh water per gram of sorbent at 90% relative humidity (RH) per day without active condensation. This leads to a total liquid delivery efficiency of 95% and an autonomous liquid delivery efficiency of 71%, the record among reported atmospheric water harvesters.

Hybrid organic PVDF-inorganic M-rGO-TiO2 (M = Ag, Pt) nanocomposites for multifunctional volatile organic compound sensing and photocatalytic degradation-H2 production

This work focused on the development of a hybrid organic-inorganic TiO2 nanocomposite, which demonstrates the first ever report on harmful volatile organic compound (VOC) sensing and photocatalytic degradation-H2 production. The sensing and photocatalytic properties are enhanced by the synergetic effects of well-structured TiO2 nanotubes, metal nanoparticles and reduced graphene oxide loading for enhanced light absorption and charge-transfer kinetics. Hybridization of a functionalized TiO2 nanocomposite with a polyvinylidene fluoride (PVDF) matrix induced strong cross-linking networks between the inorganic-organic components, which promote mechanical reinforcement-flexibility and highly porous asymmetric structures. The developed solution processable nanocomposite has immense potential to remedy the global environmental and energy issues by producing clean water/air and energy from organic compound waste.

Probing the morphology-device relation of Fe₂O₃ nanostructures towards photovoltaic and sensing applications

A lot of research on nanomaterials has been carried out in recent years. However, there is still a lack of nanostructures that have a combination of superior properties; both efficient electron transport and high surface area. Here, the authors have tried to develop hybrid α-Fe(2)O(3) flower-like morphology which exhibits both superior electron transport and high surface area. Intrigued by the unique properties of Fe(2)O(3) at the nanoscale and its abundance in nature, we have demonstrated a facile template-free solution based synthesis of hybrid α-Fe(2)O(3) comprising nanopetals nucleating radially from a 3D core. Due to its simplicity, the synthesis process can be easily reproduced and scaled up. We carried out in-depth studies on gas sensing and dye-sensitized solar cell (DSSC) device characterization so as to gain an understanding of how surface area and transport properties are affected by variation in morphology. The hybrid α-Fe(2)O(3) nanostructures are studied as potential candidates for gas sensors and for the first time as a working electrode for DSSC.

Investigation of ionic conductivity and long-term stability of a LiI and KI coupled diphenylamine quasi-solid-state dye-sensitized solar cell

In this work, enhancement of ionic conductivity and long-term stability through the addition of diphenylamine (DPA) in poly(ethylene oxide) (PEO) is demonstrated. Potassium iodide (KI) is adopted as the crystal growth inhibitor, and DPA is used as a charge transport enhancer in the electrolyte. The modified electrolyte is used with titanium dioxide (TiO2) nanoparticles, which is systematically tuned to obtain high surface area. The dye-sensitized solar cell (DSSC) showed a photocurrent of 14 mAcm2 with a total conversion efficiency of 5.8% under one sun irradiation. DPA enhances the interaction of the TiO2 nanoparticle film and the I-/I3- electrolyte leading to high ionic conductivity (3.5 × 10-3 Scm-1), without compromising on the electrochemical and mechanical stability. Electrochemical impedance spectroscopy (EIS) studies show that electron transport and electron lifetime are enhanced in the DPA added electrolyte due to reduced sublimation of iodine. The most promising feature of the electrolyte is increased device stability with 89% of the overall efficiency preserved even after 40 days.

Formation of hybrid structures: copper oxide nanocrystals templated on ultralong copper nanowires for open network sensing at room temperature

A facile large-scale synthesis approach for producing intrinsically p-type nanowires with uniform coverage of nanocrystals to form a highly interconnected porous nanowire network is of great demand for p-type sensing. Here, we have demonstrated synthesis of a very high aspect ratio (10(2)-10(5)) open network of interconnected hybrid nanocrystals-nanowire copper and copper oxide nanomaterials. The copper nanowire scaffold is employed to realize a porous and highly interconnected network of hybrid metal-metal oxide nanocrystal-nanowire structures. The structural and composition tunability of the hybrid nanomaterials is demonstrated. The hybrid copper-copper oxide nanowires exhibit enhanced gas/light sensing properties without any operating temperature. This may be attributed to enhanced medium diffusion due to the porous network of highly interconnected nanocrystal-nanowire structures.

A novel maskless approach towards aligned, density modulated and multi-junction ZnO nanowires for enhanced surface area and light trapping solar cells

A maskless method of employing polymer growth inhibitor layers is used to modulate the conflicting parameters of density and alignment of multi-junction nanowires via large-scale low temperature chemical route. This low temperature chemical route is shown to synthesize multi-junction nanostructures without compromising the crystal quality at the interfaces. The final morphology of optimized multi-junctions nanowire arrays can be demonstrated on various substrates due to substrate independence and low temperature processing. Here, we also fabricated devices based on density modulated multi-junction nanowires tuned to infiltrate nanoparticles. The fabrication of hierarchically structured nanowire/nanoparticles composites presents an advantageous structure, one that allows nanoparticles to provide large surface areas for dye adsorption, whilst the nanowires can enhance the light harvesting, electron transport rate, and also the mechanical properties of the films. This work can be of great scientific and commercial interest since the technique employed is of low temperature (<90 degrees C) and economical for large-scale solution processing, much valued in today's flexible display and photovoltaic industries.

Mesophase ordering of TiO2 film with high surface area and strong light harvesting for dye-sensitized solar cell

Mesophase ordering and structuring are carried out to attain optimized pore morphology, high crystallinity, stable porous framework, and crack-free mesoporous titanium dioxide (TiO(2)) films. The pore structure (quasi-hexagonal and lamellar) can be controlled via the concentration of copolymer, resulting in two different types of micellar packing. The calcination temperature is also controlled to ensure a well-crystalline and stable porous framework. Finally, the synthesized mesoporous TiO(2) film is modified by adding P25 nanoparticles, which act as scattering centers and function as active binders to prevent formation of microcracks. Adding P25 nanoparticles into mesoporous structure helps to provide strong light-harvesting capability and large surface area for high -efficiency dye-sensitized solar cells (DSSC). The short-circuit photocurrent density (J(sc)) of the cell made from mixture of mesoporous TiO(2) and P25 nanoparticles displays a higher efficiency of approximately 6.5% compared to the other homogeneous films. A combination of factors such as increased surface area, introduction of light-scattering particles, and high crystallinity of the mesoporous films leads to enhanced cell performance.

Controlled synthesis and application of ZnO nanoparticles, nanorods and nanospheres in dye-sensitized solar cells

Several important synthetic parameters such as precursor concentration, rate of evaporation and reaction time are found to determine the growth of ZnO nanostructures. These reaction parameters can be tailored and tuned to produce a variety of nanostructures ranging from nanoparticles, nanorods and nanospheres. The nanorods are structurally uniform made up of crystallographically oriented attached nanoparticles while the nanospheres are made up of several closely packed and randomly aligned nanocrystallites. XRD spectra of both the nanoparticles and nanorods exhibit typical diffraction peaks of a well-crystalline wurtzite ZnO structure. Finally, solar cells made up of ZnO nanoparticles and nanorods electrodes with absorbed ruthenium dye (N3) were measured to have a power conversion efficiency of 0.87% and 1.32%, respectively.

Gas sensing properties of tin oxide nanostructures synthesized via a solid-state reaction method

A high-yield synthesis of SnO(2) nanoparticles via a facile, economical and easily scalable solid-state molten salt synthesis method has been demonstrated. The inorganic additive, molar ratios of chemicals and annealing temperature were found to control the size and porosity of the SnO(2) nanoparticles. The synthesized SnO(2) nanostructures were uniform, well dispersed and exhibited high crystallinity. Hydrogen sensors made from the SnO(2) nanoparticles were found to possess high sensitivity and stability. Other than tailoring the material's structure in terms of size and porosity, another potential method of enhancing the gas sensitivity is functionalization with noble Pd metal.