| 1. |
- Kyaw, H H, et al.
(author)
-
The influence of initial gold nanoparticles layer on migration of silver nanoparticles in silver/glass matrix
- 2019
-
In: Thin Solid Films. - : Elsevier. - 1879-2731 .- 0040-6090. ; 685, s. 216-224
-
Journal article (peer-reviewed)abstract
- A thin layer of gold nanoparticles (AuNPs) was deposited on glass substrates followed by subsequent deposition of silver nanoparticles (AgNPs) on it. Both AuNPs and AgNPs layers were fabricated by DC magnetron sputtering with inert gas condensation technique. The effect of initial thin layer of AuNPs have on the transformation of AgNPs surface structure by post annealing at 500 degrees C and 600 degrees C in air was investigated. The influence of post annealing temperature on the surface morphology was studied by atomic force microscopy and post annealing at 500 degrees C reduce the size of AgNPs along with the formation of some AgNPs inside the glass matrix. At 600 degrees C, aggregation of AuNPs on the surface was observed and increased in the number of AgNPs that diffused into the glass matrix. X-ray photoelectron spectroscopy was employed to study the surface composition and chemical states. The temperature dependence of Ag diffusion into the glass matrix was characterised and observed by UV-visible absorption spectroscopy and cross sectional transmission electron microscopy. Furthermore, ultraviolet photoelectron spectroscopy revealed a new shoulder related to Au 6 s hybridized with Au 5d and Ag 4d bands in the 1-4 eV regions, which affirmed the metallic character of AgNPs/AuNPs/glass system at higher annealing temperature. By introducing AuNPs on glass prior to AgNPs deposition, novel properties such as limited Ag ion diffusion and evaporation were found and problems previously encountered in AgNPs/glass system were avoided. The proposed AgNPs/AuNPs/glass system can be useful in plasmonic applications such as chroma filters and photonic devices.
|
|
| 2. |
- Yi, Chuixiang, et al.
(author)
-
Climate control of terrestrial carbon exchange across biomes and continents
- 2010
-
In: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 5:3
-
Journal article (peer-reviewed)abstract
- Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various ecosystems over six continents with a total of 559 site-years. We find that NEE observed at eddy covariance sites is (1) a strong function of mean annual temperature at mid-and high-latitudes, (2) a strong function of dryness at mid-and low-latitudes, and (3) a function of both temperature and dryness around the mid-latitudinal belt (45 degrees N). The sensitivity of NEE to mean annual temperature breaks down at similar to 16 degrees C (a threshold value of mean annual temperature), above which no further increase of CO2 uptake with temperature was observed and dryness influence overrules temperature influence.
|
|
| 3. |
- Al-Saadi, Mubarak J., et al.
(author)
-
Influence of Atomic Hydrogen, Band Bending, and Defects in the Top Few Nanometers of Hydrothermally Prepared Zinc Oxide Nanorods
- 2017
-
In: Nanoscale Research Letters. - : Springer. - 1931-7573 .- 1556-276X. ; 12
-
Journal article (peer-reviewed)abstract
- We report on the surface, sub-surface (top few nanometers) and bulk properties of hydrothermally grown zinc oxide (ZnO) nanorods (NRs) prior to and after hydrogen treatment. Upon treating with atomic hydrogen (H*), upward and downward band bending is observed depending on the availability of molecular H2O within the structure of the NRs. In the absence of H2O, the H* treatment demonstrated a cleaning effect of the nanorods, leading to a 0.51 eV upward band bending. In addition, enhancement in the intensity of room temperature photoluminescence (PL) signals due to the creation of new surface defects could be observed. The defects enhanced the visible light activity of the ZnO NRs which were subsequently used to photocatalytically degrade aqueous phenol under simulated sunlight. On the contrary, in the presence of H2O, H* treatment created an electronic accumulation layer inducing downward band bending of 0.45 eV (similar to 1/7th of the bulk ZnO band gap) along with the weakening of the defect signals as observed from room temperature photoluminescence spectra. The results suggest a plausible way of tailoring the band bending and defects of the ZnO NRs through control of H2O/H* species.
|
|
| 4. |
- Bora, T., et al.
(author)
-
Highly efficient ZnO/Au Schottky barrier dye-sensitized solar cells : Role of gold nanoparticles on the charge-transfer process
- 2011
-
In: Beilstein Journal of Nanotechnology. - : Beilstein Institut. - 2190-4286. ; 2:1, s. 681-690
-
Journal article (peer-reviewed)abstract
- Zinc oxide (ZnO) nanorods decorated with gold (Au) nanoparticles have been synthesized and used to fabricate dye-sensitized solar cells (DSSC). The picosecond-resolved, time-correlated single-photon-count (TCSPC) spectroscopy technique was used to explore the charge-transfer mechanism in the ZnO/Au-nanocomposite DSSC. Due to the formation of the Schottky barrier at the ZnO/Au interface and the higher optical absorptions of the ZnO/Au photoelectrodes arising from the surface plasmon absorption of the Au nanoparticles, enhanced power-conversion efficiency (PCE) of 6.49% for small-area (0.1 cm(2)) ZnO/Au-nanocomposite DSSC was achieved compared to the 5.34% efficiency of the bare ZnO nanorod DSSC. The TCSPC studies revealed similar dynamics for the charge transfer from dye molecules to ZnO both in the presence and absence of Au nanoparticles. A slower fluorescence decay associated with the electron recombination process, observed in the presence of Au nanoparticles, confirmed the blocking of the electron transfer from ZnO back to the dye or electrolyte by the Schottky barrier formed at the ZnO/Au interface. For large area DSSC (1 cm(2)), similar to 130% enhancement in PCE (from 0.50% to 1.16%) was achieved after incorporation of the Au nanoparticles into the ZnO nanorods.
|
|
| 5. |
- Bora, T., et al.
(author)
-
Plasmon resonance enhanced zinc oxide photoelectrodes for improvement in performance of dye sensitized solar cells
- 2014
-
In: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 771, s. 91-101
-
Journal article (peer-reviewed)abstract
- Nanocomposites of vertically aligned zinc oxide (ZnO) nanorod arrays incorporated with gold (Au) nanoparticles have been used as photoelectrodes to fabricate dye sensitized solar cells (DSSCs). Due to the surface plasmon resonance of the Au nanoparticles, the nanocomposite photoelectrodes demonstrate enhancement in the visible light absorption resulting in ~8% higher photocurrent compared to ZnO photoelectrode based DSSCs fabricated without any Au nanoparticles. In addition to the higher optical absorption due to the gold nanoparticles, a Schottky barrier forms at the ZnO/Au interface preventing the back electron transfer from the conduction band of the semiconductor nanorods to the redox electrolyte providing improvement in the charge separation at the nanocomposite photoelectrode. Upon incorporation of Au nanoparticles, the overall efficiency of the DSSC increased from 2. 41% to 3. 27%. The role of Au nanoparticles on the performance of the DSSCs for varying concentration of the Au nanoparticles as well as the post-growth annealing treatment of the nanocomposite photoelectrode is reported.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Kyaw, T. L., et al.
(author)
-
Cost-effectiveness of Digital Tools for Behavior Change Interventions Among People With Chronic Diseases: Systematic Review
- 2023
-
In: Interactive Journal of Medical Research. - : JMIR Publications Inc.. - 1929-073X. ; 12
-
Journal article (peer-reviewed)abstract
- Background: Chronic diseases, including cardiovascular diseases, diabetes, chronic obstructive pulmonary disease, and cerebrovascular diseases, contribute to the most significant disease burden worldwide, negatively impacting patients and their family members. People with chronic diseases have common modifiable behavioral risk factors, including smoking, alcohol overconsumption, and unhealthy diets. Digital-based interventions for promoting and sustaining behavioral changes have flourished in recent years, although evidence of the cost-effectiveness of such interventions remains inconclusive. Objective: In this study, we aimed to investigate the cost-effectiveness of digital health interventions for behavioral changes among people with chronic diseases. Methods: This systematic review evaluated published studies focused on the economic evaluation of digital tools for behavioral change among adults with chronic diseases. We followed the Population, Intervention, Comparator, and Outcomes framework to retrieve relevant publications from 4 databases: PubMed, CINAHL, Scopus, and Web of Science. We used the Joanna Briggs Institute's criteria for economic evaluation and randomized controlled trials to assess the risk of bias in the studies. Two researchers independently screened, assessed the quality, and extracted data from the studies selected for the review. Results: In total, 20 studies published between 2003 and 2021 fulfilled our inclusion criteria. All the studies were conducted in high-income countries. These studies used telephones, SMS text messaging, mobile health apps, and websites as digital tools for behavior change communication. Most digital tools for interventions focused on diet and nutrition (17/20, 85%) and physical activity (16/20, 80%), and a few focused on smoking and tobacco control (8/20, 40%), alcohol reduction (6/20, 30%), and reduction of salt intake (3/20, 15%). Most studies (17/20, 85%) used the health care payer perspective for economic analysis, and only 15% (3/20) used the societal perspective. Only 45% (9/20) of studies conducted a full economic evaluation. Most studies (7/20, 35%) based on full economic evaluation and 30% (6/20) of studies based on partial economic evaluation found digital health interventions to be cost-effective and cost-saving. Most studies had short follow-ups and failed to include proper indicators for economic evaluation, such as quality-adjusted life-years, disability-adjusted life-years, lack of discounting, and sensitivity analysis. Conclusions: Digital health interventions for behavioral change among people with chronic diseases are cost-effective in high-income settings and can therefore be scaled up. Similar evidence from low-and middle-income countries based on properly designed studies for cost-effectiveness evaluation is urgently required. A full economic evaluation is needed to provide robust evidence for the cost-effectiveness of digital health interventions and their potential for scaling up in a wider population. Future studies should follow the National Institute for Health and Clinical Excellence recommendations to take a societal perspective, apply discounting, address parameter uncertainty, and apply a lifelong time horizon.(Interact J Med Res 2023;12:e42396) doi: 10.2196/42396
|
|
| 10. |
|
|
