| 1. |
- Ilyas, Muhammad Tasaduq, et al.
(författare)
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Substantial performance of copper sulfide nanotubes at high current densities for energy storage applications
- 2024
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Ingår i: Journal of Energy Storage. - : Elsevier. - 2352-152X .- 2352-1538. ; 85
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Tidskriftsartikel (refereegranskat)abstract
- This study presents the direct growth of CuS nanotubes (NTs) on nickel foam using a facile solution synthesis route. The structural, elemental and morphological analyses of CuS NTs grown Ni foam were conducted through X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscope, and field emission scanning electron microscope. The electrochemical performance of the prepared electrodes was comprehensively characterized by cyclic voltammetry (CV), galvanostatic charge discharge and electrochemical impedance spectroscopy. The CuS NTs grown electrodes delivered a specific capacitance of 1539 Fg−1 at 1 mVs−1 and 1365 Fg−1 at 5 Ag−1, demonstrating a remarkable rate capability of 66 % at an extremely high current density of 25 Ag−1. Notably, the CuS NTs electrode demonstrated good cyclic stability, as evidenced by a charge retention of 75.5 % after 3000 cycles at a high current density of 20 Ag−1. The charge storage mechanism was predominantly diffusion controlled, accomplished by analyzing CV data. Overall, this work evinces that the as-synthesized CuS NTs hold a significant promise as electrode materials for high-performance electrochemical energy storage applications.
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| 2. |
- Lasselin, Julie, et al.
(författare)
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Effect of long-term sleep restriction and subsequent recovery sleep on the diurnal rhythms of white blood cell subpopulations.
- 2015
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Ingår i: Brain, behavior, and immunity. - : Elsevier BV. - 0889-1591 .- 1090-2139. ; 47:SI, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- While acute modifications of sleep duration induces a wide array of immune function alterations, less is known of how longer periods with insufficient sleep affect immune functions and how they return to normal once recovery sleep is obtained. The purpose of the present study was to investigate the effects of five days of restricted sleep and a subsequent 7-day period of sleep recovery on white blood cell (WBC) subpopulation count and diurnal rhythms. Nine healthy males participated in a sleep protocol consisting of two baseline days (8h of sleep/night), five nights with restricted sleep (4h of sleep/night) and seven days of recovery sleep (8h of sleep/night). During nine of these days, blood was drawn hourly during night-time end every third hour during daytime, and differential WBC count was analyzed. Gradual increase across the days of sleep restriction was observed for total WBC (p<.001), monocytes (p<.001), neutrophils (p<.001) and lymphocytes (p<.05). Subsequent recovery sleep resulted in a gradual decrease in monocytes (p<.001) and lymphocytes (p=.001), but not in neutrophils that remained elevated over baseline level at the end of the 7-day recovery period. These effects were associated with altered diurnal rhythms of total WBC and neutrophils, restricted sleep being associated with higher levels during the night and at awakening, resulting in a flattening of the rhythm. The diurnal alterations were reversed when recovery sleep was allowed, although the amplitude of total WBC, neutrophils and monocytes was increased at the end of the recovery period in comparison to baseline. Altogether, these data show that long-term sleep restriction leads to a gradual increase of circulating WBC subpopulations and alterations of the respective diurnal rhythms. Although some of the effects caused by five days of restricted sleep were restored within the first days of recovery, some parameters were not back to baseline even after a period of seven recovery days.
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| 3. |
- Latif, Umar, et al.
(författare)
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In situ growth of nickel ammonium phosphate ribbons on nickel foam for supercapacitor applications
- 2023
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Ingår i: Journal of Energy Storage. - : Elsevier. - 2352-152X .- 2352-1538. ; 73:Part B
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Tidskriftsartikel (refereegranskat)abstract
- We report the in-situ growth of the nickel ammonium phosphate (NAP) ribbons on nickel (Ni) foam in a single step process using hydrothermal approach. The morphology, structure and elemental analysis of the NAP-ribbons grown on Ni foam were analyzed by scanning electron microscope (SEM), energy-dispersive x-ray analysis (EDX) and x-ray diffraction. The NAP-coated Ni foam sample was sonicated in ethanol and the obtained suspension was observed through AFM analysis to analyze the lateral dimensions of the NAP-ribbons. The obtained NAP ribbons powder was also characterized by x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Further, the NAP ribbons based electrodes were electrochemically characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge discharge analysis (GCD). NAP ribbons grown on Ni foam as electrodes achieved a specific capacitance (Csp) of 1196 Fg- 1 at 1 mVs- 1 and 1188 Fg- 1 at 1 Ag-1. The charge storage mechanism was identified and quantified by evaluating the CV data in 1-10 mVs- 1 scan rate range. It was established that at low scan rate the charge was dominantly stored by diffusion of electrolyte ions within the gaps of the NAP ribbons resulting in high energy density of 105.5 WhKg-1 at 1 Ag-1. NAP electrodes also demonstrated good cyclic stability by showing 92 % charge retention after 5000 cycles. A symmetric 2-elec-trode device comprised of NAP ribbons electrodes gave Csp of 309 Fg-1 at 1 mVs- 1 with energy density of 42.06 Wh/Kg and power density of 0.5 KW/Kg at 1 A/g current density, which is an exceptional for a symmetric supercapacitor device. The study confirms that NAP ribbons have a promising potential to be employed in the next-generation energy storage devices.
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| 4. |
- Raza, Mohsin Ali, et al.
(författare)
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Synthesis and characterization of zinc aluminate electrodes for supercapacitor applications
- 2024
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 475
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Tidskriftsartikel (refereegranskat)abstract
- We report, for the first time, the thorough electrochemical characterization of zinc aluminate spinel. Four different stoichiometric composition of zinc aluminate (ZnAl1.5O3.25, ZnAl2O4, ZnAl2.87O5.30, and ZnAl4O7) were prepared by solution combustion method. The obtained powders after calcination at 1000 °C were characterized through scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction to analyze the morphology, elemental composition and structure, respectively, of the zinc aluminate compositions. The electrodes were prepared by coating slurry of zinc aluminate, carbon black and polyvinylidene fluoride on nickel foam in a ratio of 8:1:1. The electrochemical characterization was carried out by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). ZnAl1.5O3.25 exhibited the highest specific capacity of 546 C/g at 1 mV/s and 336 C/g at 1 A/g, as appraised by CV and GCD analysis, respectively. EIS test revealed that ZnAl1.5O3.25 had the modest impedance value. The energy density value for ZnAl1.5O3.25 sample was 16.79 Wh/kg at 1 A/g with a power density of 179.9 W/kg. The as developed electrodes showed predominantly pseudo-capacitive charge storage mechanism.
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| 5. |
- Rehman, Javaid-ur, et al.
(författare)
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Sleeping during the day : effects on the 24-h patterns of IGF-binding protein 1, insulin, glucose, cortisol, and growth hormone.
- 2010
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Ingår i: European Journal of Endocrinology. - 0804-4643 .- 1479-683X. ; 163:3, s. 383-90
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Disturbed sleep is a major risk factor for metabolic disturbances, including type 2 diabetes, but the involved mechanisms are still poorly understood. We investigated how an acute shift of sleep to the daytime affected IGF-binding protein 1 (IGFBP1), which is a risk factor for diabetes. METHODS: Seven healthy men (age, 22-32 years) participated in a night sleep condition (sleep 2300-0700 h) and a day sleep condition (0700-1500 h) with hourly blood samples taken for 25 h (starting at 1900 h) and isocaloric meals every 4th hour awake. The blood samples were analyzed for IGFBP1, insulin, GH, glucose, and cortisol. RESULT: The acute shift of sleep and meal timing (to 8 h) shifted the 24-h patterns of IGFBP1, glucose, insulin, and GH to a similar degree. However, the day sleep condition also resulted in elevated levels of IGFBP1 (area under curve (AUC)+22%, P<0.05), and reduced glucose levels (AUC-7%, P<0.05) compared with nocturnal sleep. Sleeping during the day resulted in elevated cortisol levels during early sleep and reduced levels in late sleep, but also in increased levels the subsequent evening (P's<0.05). CONCLUSION: Sleep-fasting seems to be the primary cause for the elevation of IGFBP1, irrespective of sleep timing. However, sleeping during the day resulted in higher levels of IGFBP1 than nocturnal sleep, suggesting altered metabolism among healthy individuals, which may have implications for other groups with altered sleep/eating habits such as shift workers. Moreover, sleep and meal times should be accounted for while interpreting IGFBP1 samples.
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| 6. |
- Ridefelt, Peter, 1959-, et al.
(författare)
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Influences of sleep and the circadian rhythm on iron-status indices
- 2010
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 0009-9120 .- 1873-2933. ; 43:16-17, s. 1323-1328
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim was to study the influence of sampling time, food intake and sleep on tests used to screen for and monitor conditions of iron deficiency and overload. Design and methods: The 24 h variations of iron, transferrin, transferrin saturation (TS) and ferritin were studied in seven healthy individuals during standardised food intake, and during night or day sleep. Results: Iron and TS showed clear diurnal variations, with peaks at 12.6 h and 12.8 h respectively, during night sleep, and at 19.7 h and 19.3 h, respectively, during day sleep. Ferritin did not demonstrate any circadian variation. Transferrin and ferritin were unaffected by sleep-condition. Meals did not have any effect except a slight decline of transferrin. Conclusions: Time of day and sleeping patterns had great influence on iron and TS, whereas no or only minor effects are seen on the concentration of ferritin and transferrin. Meals have limited effects. (C) 2010 The Canadian Society of Clinical Chemists.
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