Vitamin D and Exercise Are Major Determinants of Natural Killer Cell Activity, Which Is Age- and Gender-Specific

BackgroundThe coronavirus-19 disease (COVID-19) pandemic reminds us of the importance of immune function, even in immunologically normal individuals. Multiple lifestyle factors are known to influence the immune function.ObjectiveThe aim was to investigate the association between NK cell activity (NKA) and multiple factors including vitamin D, physical exercise, age, and gender.MethodsThis was a cross-sectional association study using health check-up and NKA data of 2,095 subjects collected from 2016 to 2018 in a health check-up center in the Republic of Korea. NKA was measured using the interferon-γ (IFN-γ) stimulation method. The association of NKA with 25-(OH)-vitamin D (25(OH)D) and other factors was investigated by multiple logistic regression analysis.ResultsThe average age of subjects was 48.8 ± 11.6 years (52.9% of subjects were female). Among 2,095 subjects, 1,427 had normal NKA (NKA ≥ 500 pg IFN-γ/mL), while 506 had low NKA (100 ≤ NKA < 500 pg/mL), and 162 subjects had very low NKA (NKA < 100 pg/mL). Compared to men with low 25(OH)D serum level (< 20 ng/mL), vitamin D replete men (30–39.9 ng/mL) had significantly lower risk of very low NKA (OR: 0.358; 95% CI: 0.138, 0.929; P = 0.035). In women, both low exercise (OR: 0.529; 95% CI: 0.299, 0.939; P = 0.030) and medium to high exercise (OR: 0.522; 95% CI: 0.277, 0.981; P = 0.043) decreased the risk compared to lack of physical exercise. Interestingly, in men and women older than 60 years, physical exercise significantly decreased the risk. Older-age was associated with increased risk of very low NKA in men, but not in women.ConclusionPhysical exercise and vitamin D were associated with NKA in a gender- and age-dependent manner. Age was a major risk factor of very low NKA in men but not in women

SnS44– Metal Chalcogenide Ligand, S2– Metal Free Ligand, and Organic Surface Ligand Toward Efficient CdSe Quantum Dot- Sensitized Solar Cells

Inorganic surface ligands such as metal chalcogenides ligand SnS44- and metal free ligand S2- were introduced for CdSe quantum dot sensitized solar cell (QDSSC) applications. The SnS44- ligand QDs were successfully deposited onto TiO2 photoanode through metal ion coordination. In solution, metal-ammonia complexes of Zn2+, Cd2+, and Cu2+ can be coordinated by the SnS44- ligands and reverse the zeta potential. Similarly, the metal ions can be sandwiched by SnS44- ligands and the photoanode. Using the metal ion bridged SnS44- ligand QDs as the sensitizer, photovoltaic properties of the QDSSCs have been studied. Cd2+ mediated deposition case showed better photovoltaic performance than the cases of Zn2+ or Cu2+. To further investigate the surface ligand effect on QDSSC, organic/inorganic mixed surface CdSe QDs were introduced using partial ligand exchange after the deposition onto the TiO2 photoanode. The postdeposition surface ligand exchange with inorganic ligands such as SnS44- and S2- is thought to retain the initial organic ligands between QDs and TiO2 photoanode and selectively replace the QD ligands that would contact the electrolytes. Metal free S2- ligand QDSSC showed the best photovoltaic performance recording 1.4 times enhanced photocurrent and 1.5 times enhanced photoconversion efficiency when compared with the initial organic surface ligand QDSSC. Comparison studies on the photovoltaic properties of QDSSCs with different surfaces suggest that (i) the Cd-SnS44- complex and SnS44- surface ligand act as efficient electron traps hurdling the photovoltaic performance severely, (ii) S2- surface ligand works as an efficient hole trap only at the interface between the QD and TiO2, and (iii) S2- surface ligand blocks back electron transfers better than the initial organic ligand.X1186sciescopu

Layer-by-Layer Quantum Dot Assemblies for the Enhanced Energy Transfers and Their Applications toward Efficient Solar Cells

Two different quantum dots (QDs) with an identical optical band gap were prepared: one without the inorganic shell and short surface ligands (BQD) and the other with thick inorganic shells and long surface ligands (OQD). They were surface-derivatized to be positively or negatively charged and were used for layer-by-layer assemblies on TiO2. By sandwiching BQD between OQD and TiO2, OQD photoluminescence showed seven times faster decay, which is attributed to the combined effect of the efficient energy transfer from OQD to BQD with the FRET efficiency of 86% and fast electron transfer from BQD to TiO2 with the rate of 1.2 x 10(9) s(-1). The QD bilayer configuration was further applied to solar cells, and showed 3.6 times larger photocurrent and 3.8 times larger photoconversion efficiency than those of the device with the OQD being sandwiched by BQD and TiO2. This showcases the importance of sophisticated control of QD layer assembly for the design of efficient QD solar cells.X112221sciescopu

SnS₄^4– Metal Chalcogenide Ligand, S^2– Metal Free Ligand, and Organic Surface Ligand Toward Efficient CdSe Quantum Dot- Sensitized Solar Cells

Inorganic surface ligands such as metal chalcogenides ligand SnS₄^4– and metal free ligand S^2– were introduced for CdSe quantum dot sensitized solar cell (QDSSC) applications. The SnS₄^4– ligand QDs were successfully deposited onto TiO₂ photoanode through metal ion coordination. In solution, metal–ammonia complexes of Zn²⁺, Cd²⁺, and Cu²⁺ can be coordinated by the SnS₄^4– ligands and reverse the zeta potential. Similarly, the metal ions can be sandwiched by SnS₄^4– ligands and the photoanode. Using the metal ion bridged SnS₄^4– ligand QDs as the sensitizer, photovoltaic properties of the QDSSCs have been studied. Cd²⁺ mediated deposition case showed better photovoltaic performance than the cases of Zn²⁺ or Cu²⁺. To further investigate the surface ligand effect on QDSSC, organic/inorganic mixed surface CdSe QDs were introduced using partial ligand exchange after the deposition onto the TiO₂ photoanode. The postdeposition surface ligand exchange with inorganic ligands such as SnS₄^4– and S^2– is thought to retain the initial organic ligands between QDs and TiO₂ photoanode and selectively replace the QD ligands that would contact the electrolytes. Metal free S^2– ligand QDSSC showed the best photovoltaic performance recording 1.4 times enhanced photocurrent and 1.5 times enhanced photoconversion efficiency when compared with the initial organic surface ligand QDSSC. Comparison studies on the photovoltaic properties of QDSSCs with different surfaces suggest that (i) the Cd–SnS₄^4– complex and SnS₄^4– surface ligand act as efficient electron traps hurdling the photovoltaic performance severely, (ii) S^2– surface ligand works as an efficient hole trap only at the interface between the QD and TiO₂, and (iii) S^2– surface ligand blocks back electron transfers better than the initial organic ligand

Layer-by-Layer Assemblies of Semiconductor Quantum Dots for Nanostructured Photovoltaic Devices

A multilayer of quantum dots (QDs) is preferred for QD-sensitized solar cells over a monolayer counterpart to fully utilize the sunlight incident into a relatively thin-film-based photovoltaic device. A controlled assembly of QD multilayers such as layer-by-layer (LbL) assemblies can provide a model system to study the interactions between the QD layers and can offer an optimal device configuration for efficient solar power conversion. Recently, we have proposed a LbL QD assembly using electrostatic interactions of the surface charges and have successfully prepared a controlled multilayer of QD on the surface of mesoporous metal oxide films. The as-prepared tailor-made QD multilayers not only guaranteed the sufficient absorption of incident solar light but also provided a toolbox for the study and optimization of electron/energy transfers between QD layers.X112117sciescopu

Preparation of Multilayered CdSe Quantum Dot Sensitizers by Electrostatic Layer-by-Layer Assembly and a Series of Post-treatments toward Efficient Quantum Dot-Sensitized Mesoporous TiO2 Solar Cells

A multilayer of CdSe quantum dots (QDs) was prepared on the mesoporous surface of a nanoparticulate TiO2 film by a layer-by-layer (LBL) assembly using the electrostatic interaction of the oppositely charged QD surface for application as a sensitizer in QD-sensitized TiO2 solar cells. To maximize the absorption of incident light and the generation of excitons by CdSe QDs within a fixed thickness of TiO2 film, the experimental conditions of QD deposition were optimized by controlling the concentration of salt added into the QD-dissolved solutions and repeating the LBL deposition a few times. A proper concentration of salt was found to be critical in providing a deep penetration of QDs into the mesopore, thus leading to a dense and uniform distribution throughout the whole TiO2 matrix while anchoring the oppositely charged QDs alternately in a controllable way. A series of post-treatments with (1) CdCl2, (2) thermal annealing, and (3) ZnS-coating was found to be very critical in improving the overall photovoltaic properties, presumably through a better connection between QDs, effective passivation of QD's surface, and a high impedance of recombination, which were proved by transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) experiments. With a proper post-treatment of multilayered QDs as a sensitizer, the overall power conversion efficiency in the CdSe QD-sensitized TiO2 solar cells could reach 1.9% under standard illumination condition of simulated AM 1.5G (100 mW/cm(2)).X113131sciescopu

Layer-by-Layer Quantum Dot Assemblies for the Enhanced Energy Transfers and Their Applications toward Efficient Solar Cells

Two different quantum dots (QDs) with an identical optical band gap were prepared: one without the inorganic shell and short surface ligands (BQD) and the other with thick inorganic shells and long surface ligands (OQD). They were surface-derivatized to be positively or negatively charged and were used for layer-by-layer assemblies on TiO₂. By sandwiching BQD between OQD and TiO₂, OQD photoluminescence showed seven times faster decay, which is attributed to the combined effect of the efficient energy transfer from OQD to BQD with the FRET efficiency of 86% and fast electron transfer from BQD to TiO₂ with the rate of 1.2 × 10⁹ s^–1. The QD bilayer configuration was further applied to solar cells, and showed 3.6 times larger photocurrent and 3.8 times larger photoconversion efficiency than those of the device with the OQD being sandwiched by BQD and TiO₂. This showcases the importance of sophisticated control of QD layer assembly for the design of efficient QD solar cells

Layer-by-Layer Assemblies of Semiconductor Quantum Dots for Nanostructured Photovoltaic Devices

A multilayer of quantum dots (QDs) is preferred for QD-sensitized solar cells over a monolayer counterpart to fully utilize the sunlight incident into a relatively thin-film-based photovoltaic device. A controlled assembly of QD multilayers such as layer-by-layer (LbL) assemblies can provide a model system to study the interactions between the QD layers and can offer an optimal device configuration for efficient solar power conversion. Recently, we have proposed a LbL QD assembly using electrostatic interactions of the surface charges and have successfully prepared a controlled multilayer of QD on the surface of mesoporous metal oxide films. The as-prepared tailor-made QD multilayers not only guaranteed the sufficient absorption of incident solar light but also provided a toolbox for the study and optimization of electron/energy transfers between QD layers

Layer-by-Layer-Assembled Quantum Dot Multilayer Sensitizers: How the Number of Layers Affects the Photovoltaic Properties of One-Dimensional ZnO Nanowire Electrodes

X1177sciescopu

The influence of physical activity on risk of cardiovascular disease in people who are obese but metabolically healthy.

The metabolic outcomes of metabolically healthy obesity (MHO) remain controversial. The aim of the present study was to determine the effect of physical activity on the cardiovascular disease (CVD) outcomes of MHO. The study included participants who were followed for 10 years and recruited from the Korean Genome and Epidemiology Study (KoGES), a population-based cohort study. Participants with previously recorded CVDs or cancer, or who had received steroids or anticoagulants at baseline were excluded. A total of 8144 participants (3,942 men and 4,202 women) fulfilled inclusion criteria. In a multivariate Cox regression model adjusted for age and sex, MHO participants were not at elevated risk of CVD compared with their metabolically healthy non-obese (MHNO) counterparts (HR, 1.28; 95% CI, 0.96-1.71), although both the non-obese (HR, 1.50; 95% CI, 1.19-1.90) and obese (HR, 1.85; 95% CI, 1.48-2.30) participants with metabolic abnormalities were at elevated risk. However, in the subgroup analysis by physical activity, physically inactive MHO participants had a significantly higher HR for CVD events compared to active MHNO participants (HR, 1.54; 95% CI, 1.03-2.30), while active MHO participants were not at elevated risk (HR, 1.15; 95% CI, 0.70-1.89). Physically inactive MHO participants had significantly increased risk of CVD compared to physically active MHNO participants whereas physically active MHO participants did not