Improvement of spectral response using tandem structured dye-sensitized solar cells

Department of Chemical EngineeringDye-sensitized solar cells (DSSCs) have attracted great attention and one of the strong alternatives to conventional Si-based solar cells because of their advantages such as transparency, comparable efficiency, various colors, and simple processes with low costs, etc. In order to get high solar-toelectrical conversion efficiency, improved the spectral response of the sensitizer is necessary. At the principals of DSSCs, the dye molecules act as a primary active component for the absorption of the solar spectrum and generating electrons. If the dye molecules should absorb the sun’s spectrum as wide as possible, the number of generated electrons should be increased and higher conversion efficiency can be achieved with increased spectral response. However, the individual sensitizer can only absorb its own particular range of wavelength. To maximize energy harvesting of DSSCs, many researchers approaching to make a panchromatic system, which could absorb the photons over the entire range of wavelength. Here, I present the prominent way to fabricating panchromatic structured dye-sensitized solar cells. In order to fabricate working electrodes, newly method of pre-dye coating (PDC) of TiO2 nanoparticles (NPs) and an approach of a dip coating have been adopted for the panchromatic DSSCs. A bi-layer photoanode with two distinct TiO2 layer, which were individually sensitized with N719 and N749 dyes were coated on a transparent conducting oxide (TCO) in a sequenced manner. The improvement of spectral response and efficiency of panchromatic DSSCs has been checked with the absorption characteristics of each dye. Furthermore, by using intensity modulated photovoltaic spectroscopy (IMVS), I could check the dynamic electron kinetic and calculate lifetime in ambient conditions with τn = 1/(2πƒmin(IMVS)). In addition, here I report a novel structure of DSSCs with reversely form by constructing all the components together as one substrate. With this new structure, comparable cell properties was achieved to the conventional structure. The electrochemical properties and photochemical properties were checked by electrochemical impedance spectroscopy. Moreover, the present approach could be an encouraging new direction in research while facilitating the fabrication of hybrid-tandem solar cells. Furthermore, I also present a systematic approach of carbon black in order to optimize the catalytic ability of iodide/tri-iodide electrolyte. Replacement of the Pt counter electrode with an inexpensive but electro-chemically stable alternative is one key technological challenge that must be overcome to make DSSCs more economical. Based on the electrochemical analysis, the chargetransfer resistance and photo-electrochemical properties were characterized.ope

A study of TiO2/carbon black composition as counter electrode materials for dye-sensitized solar cells

This study describes a systematic approach of TiO2/carbon black nanoparticles with respect to the loading amount in order to optimize the catalytic ability of triiodide reduction for dye-sensitized solar cells. In particular, the cell using an optimized TiO2and carbon black electrode presents an energy conversion efficiency of 7.4% with a 5:1 ratio of a 40-nm TiO2to carbon black. Based on the electrochemical analysis, the charge-transfer resistance of the carbon counter electrode changed based on the carbon black powder content. Electrochemical impedance spectroscopy and cyclic voltammetry study show lower resistance compared to the Pt counter electrode. The obtained nanostructures and photo electrochemical study were characterized.open6

Design of a Wideband Printed Patch Dipole Antenna with a Balanced On-Board Feeding Network

This paper proposes a wideband printed patch dipole antenna with a simple on-board feeding network. The proposed antenna is composed of two dipole radiators, a transmission line, and an on-board feeding network with a chip balun. The dipole radiators are printed on a substrate, and the edges of the radiators are truncated to create a hexagonal shape with wide impedance-matching characteristics. The chip balun is embedded in an RO4003C printed circuit board (PCB) to excite differential feeding to each radiator with a 180° phase difference. The proposed antenna is optimized using a CST Studio full electromagnetic software tool, and it is fabricated and measured in an anechoic chamber. The measured fractional bandwidth for the reflection coefficient below −10 dB is 79.5%, and the proposed antenna has a measured gain of 7.1 dBi at 3.5 GHz

High performance dye sensitized solar cells by adding titanate co-adsorbant

The open circuit voltage and the short circuit current density of dye sensitized solar cells were increased by adding a titanate co-adsorbant as a blocking agent. This blocking agent effectively prevents back electron transfer. As a result, DSSCs with titanate co-adsorbant showed significantly increased energy conversion efficiency.close0

Exploring the Association between Thyroid Function and Frailty: Insights from Representative Korean Data

Background This study investigates the association between thyroid function and frailty in the old patients using representative data. Methods The study was conducted using data from the Korea National Health and Nutrition Examination Survey conducted from 2013 to 2015. The study population included 2,416 participants aged 50 years and older with available thyroid function test data. Frailty assessment was performed using the Fried frailty phenotype. The prevalence of frailty was analyzed across different thyroid diseases and thyroid function parameters. Results The significant association between thyroid dysfunction and frailty was observed in overt hyperthyroidism and subclinical hyperthyroidism. After adjusting for various factors, the association between thyroid dysfunction and frailty remained significant. On the other hand, overt hypothyroidism did not show a significant association with frailty in the adjusted analysis. For individuals with overt hyperthyroidism and subclinical hyperthyroidism, higher levels of free thyroxine (FT4) were significantly associated with an increased risk of frailty (aOR >999; 95% CI, >999 to 999). Among individuals with overt hypothyroidism, lower level of FT4 levels and high thyrotropin (TSH) levels showed a significant association with frailty risk (FT4: aOR, <0.01; TSH: aOR, 999). In participants with subclinical hypothyroidism, there were no significant associations between parameters for thyroid and frailty risk. Conclusion These findings suggest that thyroid dysfunction, particularly overt hyperthyroidism and subclinical hyperthyroidism, may be associated with an increased risk of frailty in the old patients

CD160 serves as a negative regulator of NKT cells in acute hepatic injury

[EN] CD160 and BTLA both bind to herpes virus entry mediator. Although a negative regulatory function of BTLA in natural killer T (NKT) cell activation has been reported, whether CD160 is also involved is unclear. By analyzing CD160−/− mice and mixed bone marrow chimeras, we show that CD160 is not essential for NKT cell development. However, CD160−/− mice exhibit severe liver injury after in vivo challenge with α-galactosylceramide (α-GalCer). Moreover, CD160−/− mice are more susceptible to Concanavalin A challenge, and display elevated serum AST and ALT levels, hyperactivation of NKT cells, and enhanced IFN-γ, TNF, and IL-4 production. Lastly, inhibition of BTLA by anti-BTLA mAb aggravates α-GalCer-induced hepatic injury in CD160−/− mice, suggesting that both CD160 and BTLA serve as non-overlapping negative regulators of NKT cells. Our data thus implicate CD160 as a co-inhibitory receptor that delivers antigen-dependent signals in NKT cells to dampen cytokine production during early innate immune activationSIWe thank the NIH Tetramer Core Facility for providing PBS 57 ligand loaded CD1d Tetramers. Further, we thank the staffs of Gyerim Experimental Animal Resource Center for animal care and technical assistance. K.-M. Lee was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future planning (NRF-2016M3A9B6948342, NRF- 2017R1A2B3004828, and NRF-2018M3A9D3079288). S.-J. Kim was supported by the Korea Health Industry Development Institute (KHIDI-HI14C2640) grant funded by Korea Government. S.-J. Ha was supported by a grant from the NRF (NRF- 2018R1A2A1A05076997). T.-J. Kim was additionally supported by a grant from the NRF (NRF-2016R1A6A3A04009698

Induction of fibroblast senescence generates a non-fibrogenic myofibroblast phenotype that differentially impacts on cancer prognosis

Cancer-associated fibroblasts (CAF) remain a poorly characterized, heterogeneous cell population. Here we characterized two previously described tumor-promoting CAF sub-types, smooth muscle actin (SMA)-positive myofibroblasts and senescent fibroblasts, identifying a novel link between the two. Analysis of CAF cultured ex vivo, showed that senescent CAF are predominantly SMA-positive; this was confirmed by immunochemistry in head &amp; neck (HNSCC) and esophageal (EAC) cancers. In vitro, we found that fibroblasts induced to senesce develop molecular, ultrastructural and contractile features typical of myofibroblasts and this is dependent on canonical TGF-? signaling. Similar to TGF-?1-generated myofibroblasts, these cells secrete soluble factors that promote tumor cell motility. However, RNA-sequencing revealed significant transcriptomic differences between the two SMA-positive CAF groups, particularly in genes associated with extracellular matrix (ECM) deposition and organization, which differentially promote tumor cell invasion. Notably, second harmonic generation imaging and bioinformatic analysis of SMA-positive human HNSCC and EAC showed that collagen fiber organization correlates with poor prognosis, indicating that heterogeneity within the SMA-positive CAF population differentially impacts on survival. These results show that non-fibrogenic, SMA-positive myofibroblasts can be directly generated through induction of fibroblast senescence and suggest that senescence and myofibroblast differentiation are closely linked processes

Physical activity and reduced risk of fracture in thyroid cancer patients after thyroidectomy — a nationwide cohort study

ObjectivesLevothyroxine suppressive therapy following thyroidectomy for thyroid cancer patients is considered as a risk factor for osteoporosis and fragility fractures. We evaluated the association of regular exercise and exercise habit change with fracture risk in adults older than 40 years who underwent thyroidectomy for thyroid cancer.MethodsWe enrolled the patients who underwent thyroidectomy for thyroid cancer older than 40 years between 2010 and 2016 from the Korean National Health Insurance Service data, and they were followed through 2019. Based on the questionnaire of health examination within 2 years before and after surgery, whether regular exercise once a week was evaluated. The reference group for the statistical analysis was the continuing lack of physical activity group that did not exercise before or after surgery. For fractures newly diagnosed during the follow-up period, univariate and multivariate Cox regression analyses were performed for risk evaluation.ResultsWe evaluated 74,774 subjects, of whom 2,924 (3.9%) experienced any fractures during a median follow-up of 4.5 years. Compared with the group consistently lack of physical activity, the group that exercised before and after surgery showed a significant decrease in the risk of any fracture, vertebral fracture, and hip fracture: adjusted hazard ratio 0.848 (95% Confidence Interval 0.771–0.932), 0.703 (0.591–0.836), and 0.405 (0.224–0.732), respectively. For vertebral fracture, a significant reduction in fracture risk was confirmed even in patients who started their regular exercise after surgery: adjusted hazard ratio 0.779 (0.648–0.936). The risk reduction for vertebral fractures upon the initiation of exercise was found to be significant in the high-risk groups of patients: women and total thyroidectomy patients.ConclusionWe suggest that maintaining or starting regular exercise after surgery may help prevent fractures in thyroid cancer patients older than 40 years who have undergone thyroidectomy