Three amphiphilic block copolymers are employed to form polymeric micelles and function as nanocarriers to disperse hydrophobic aggregation‐induced emission (AIE) dyes, 1,1,2,3,4,5‐hexaphenylsilole ...(HPS) and/or bis(4‐(N‐(1‐naphthyl) phenylamino)‐phenyl)fumaronitrile (NPAFN), into aqueous solution for biological studies. Compared to their virtually non‐emissive properties in organic solutions, the fluorescence intensity of these AIE dyes has increased significantly due to the spatial confinement that restricts intramolecular rotation of these dyes and their better compatibility in the hydrophobic core of polymeric micelles. The effect of the chemical structure of micelle cores on the photophysical properties of AIE dyes are investigated, and the fluorescence resonance energy transfer (FRET) from the green‐emitting donor (HPS) to the red‐emitting acceptor (NPAFN) is explored by co‐encapsulating this FRET pair in the same micelle core. The highest fluorescence quantum yield (∼62%) could be achieved by encapsulating HPS aggregates in the micelles. Efficient energy transfer (>99%) and high amplification of emission (as high as 8 times) from the NPAFN acceptor could also be achieved by spatially confining the HPS/NPAFN FRET pair in the hydrophobic core of polymeric micelles. These micelles could be successfully internalized into the RAW 264.7 cells to demonstrate high‐quality fluorescent images and cell viability due to improved quantum yield and reduced cytotoxicity.
Highly efficient fluorescence probes are achieved through the encapsulation of aggregation‐induced emission molecules, 1,1,2,3,4,5‐hexaphenylsilole (HPS) and/or bis(4‐(N‐(1‐naphthyl) phenylamino)‐phenyl)fumaronitrile (NPAFN) in the core of polymeric micelles. Bright fluorescence cell images are shown with tunable colors of green directly from HPS aggregates and red through efficient fluorescence resonance energy transfer (FRET) from HPS aggregates to NPAFN aggregates.
•All six theoretical models have good explanatory power of behavioral intention (BI).•Based on variance explanation, the motivational model (MM) and the technology acceptance model (TAM) have ...stronger explanatory powers.•The theory of planned behavior (TPB) and the TAM have larger effect size compared to other theories.•Perceived usefulness (PU), attitude (ATT), cloud service quality (CSQ), perceived behavior control (PBC), result demonstration (RD), visibility (VIS), and cloud self-efficacy (CSE) are important factors of a unified model.
Cloud computing is an innovative information technology that has been applied to education and has facilitated the development of cloud computing classrooms; however, student behavioral intention (BI) toward cloud computing remains unclear. Most researchers have evaluated, integrated, or compared only few theories to examine user BI. In this study, we tested, compared, and unified six well-known theories, namely service quality (SQ), self-efficacy (SE), the motivational model (MM), the technology acceptance model (TAM), the theory of reasoned action or theory of planned behavior (TRA/TPB), and innovation diffusion theory (IDT), in the context of cloud computing classrooms. This empirical study was conducted using an online survey. The data collected from the samples (n=478) were analyzed using structural equation modeling. We independently analyzed each theory, by formulating a united model. The analysis yielded three valuable findings. First, all six theoretical models and the united model exhibited adequate explanatory power. Second, variance explanation, Chi-squared statistics, effect size, and predictive relevance results revealed the ranking importance of the theoretical models. Third, the united model provided a comprehensive understanding of the factors that significantly affect the college students’ BI toward a cloud computing classroom. The discussions and implications of this study are critical for researchers and practitioners.
A novel ladder‐type donor (IDTT) is developed by substituting the two outward thiophenes of the IDT donor with two thieno3,2‐bthiophenes. The polymer derived from this donor possesses longer ...effective conjugation and better planarity, which improves electron delocalization along the polymer backbone and charge mobility. The polymer solar cell device using PIDTT‐DFBT shows a high power conversion efficiency of 7.03% with a large open‐circuit voltage of 0.95 V without using any additives or post‐solvent/thermal annealing processes.
Background and purpose
This study quantified the total brain and periventricular white matter hyperintensity (WMH) burdens in patients with early Parkinson’s disease (PD) and explored their ...associations with cardiovascular risk factors and cognitive performance.
Methods
A total of 175 non‐demented patients with early PD who had undergone baseline brain magnetic resonance imaging were included. Comprehensive neurocognitive testing was conducted to identify PD with mild cognitive impairment (PD‐MCI) and to evaluate performances in individual cognitive domains. Cardiovascular risk was expressed as a modified Framingham 10‐year cardiovascular risk score (mFRS).
Results
A total of 53.7% of this early PD cohort fulfilled the diagnostic criteria for PD‐MCI. An increase in mFRS was significantly associated with increases in the total brain WMH (P = 0.015) and periventricular WMH (P = 0.040) burden, independent of age and gender. The periventricular WMH burden was significantly associated with PD‐MCI (P = 0.046) in early PD, independent of cardiovascular risk factors. Patients in the 5th quintile of periventricular WMH burden were 8.6 times more likely to have PD‐MCI compared with patients in the 1st quintile of periventricular WMH burden (P = 0.004). However, total brain WMH burden was not associated with PD‐MCI (P = 0.158). In individual cognitive domains, heavier periventricular WMH burden was associated with worse executive function and visuospatial function independent of cardiovascular risk factors.
Conclusion
Periventricular WMHs are a useful imaging biomarker for cognitive impairment in early PD. Cardiovascular risk factors, although associated with periventricular WMHs, were unable to fully explain the association between periventricular WMHs and cognitive impairment in early PD.
In this study, we investigate the influence of molecular geometry of the donor polymers and the perylene diimide dimers (di‐PDIs) on the bulk heterojunction (BHJ) morphology in the nonfullerene ...polymer solar cells (PSCs). The results reveal that the pseudo 2D conjugated poly4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo1,2‐b;4,5‐b′dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno3,4‐bthiophene‐)‐2‐carboxylate‐2‐6‐diyl) (PTB7‐Th) has better miscibility with both bay‐linked di‐PDI (B‐di‐PDI) and hydrazine‐linked di‐PDI (H‐di‐PDI) compared to its 1D analog, poly4,8‐bis(2‐ethylhexyl)oxybenzo1,2‐b:4,5‐b′dithiophene‐2,6‐diyl3‐fluoro‐2‐(2‐ethylhexyl)carbonylthieno3,4‐bthiophenediyl (PTB7), to facilitate more efficient exciton dissociation in the BHJ films. However, the face‐on oriented π–π stacking of PTB7‐Th is severely disrupted by the B‐di‐PDI due to its more flexible structure. On the contrary, the face‐on oriented π–π stacking is only slightly disrupted by the H‐di‐PDI, which has a more rigid structure to provide suitable percolation pathways for charge transport. As a result, a very high power conversion efficiency (PCE) of 6.41% is achieved in the PTB7‐Th:H‐di‐PDI derived device. This study shows that it is critical to pair suitable polymer donor and di‐PDI‐based acceptor to obtain proper BHJ morphology for achieving high PCE in the nonfullerene PSCs.
Suitable selection of perylene diimide dimer (di‐PDI)‐based acceptors and polymer donors is essential to optimize the bulk heterojunction morphology. When blended with the 2D polymer, PTB7‐Th, the rigidly hydrazine‐linked di‐PDI affords the recorded power conversion efficiency of 6.4% due to excellent miscibility for efficient exciton dissociation and appropriate percolation pathways for charge transport.
Abstract
Power conversion efficiency and long-term stability are two critical metrics for evaluating the commercial potential of organic photovoltaics. Although the field has witnessed a rapid ...progress of efficiency towards 19%, the intrinsic trade-off between efficiency and stability is still a challenging issue for bulk-heterojunction cells due to the very delicate crystallization dynamics of organic species. Herein, we developed a class of non-fullerene acceptors with varied side groups as an alternative to aliphatic chains. Among them, the acceptors with conjugated side groups show larger side-group torsion and more twisted backbone, however, they can deliver an efficiency as high as 18.3% in xylene-processed cells, which is among the highest values reported for non-halogenated solvent processed cells. Meanwhile, decent thermal/photo stability is realized for these acceptors containing conjugated side groups. Through the investigation of the geometry
–
performance
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stability relationship, we highlight the importance of side-group steric hinderance of acceptors in achieving combined high-performance, stable, and eco-friendly organic photovoltaics.
In this study, researchers describe the clinical characteristics of coronavirus disease 2019 in a selected cohort of 1099 patients with laboratory-confirmed disease throughout mainland China during ...the first 2 months of the current outbreak.
Summary Objective This study aimed to investigate the spatial and temporal subchondral bone change of Dunkin–Hartley (DH) strain guinea pigs spontaneous osteoarthritis (OA) model at early stage with ...three-dimensional Microfocal Computed Tomography (Micro-CT) analysis, histology and immunohistochemistry. Materials and methods Knee joints of DH and Bristol Strain 2 (BS2) guinea pigs were analyzed at 1, 2 and 3 months of age for early staged subchondral bone ultrastructure change of OA by Micro-CT and histology. And cartilage degeneration was monitored by histological examination. In addition, expression of Osterix was quantified by immunohistochemistry. Results Microscopic cartilage degeneration was not found at first 3 months in both DH and BS2 guinea pigs. Subchondral bone sclerosis with trabecular ultrastructure turnover was characterized in subchondral bone of DH guinea pigs. Increased thickness, bone mineral density with decreased porosity were defined in subchondral plate of DH guinea pigs. Subchondral trabecular bone was found to be plate-like, convex and isotropy with higher bone volume. Histology confirmed the finding of lower porosity at osteochondral junction and increased bone volume. Immunohistochemistry revealed that the early OA subchondral bone change may be due to elevated level of osteoblast differentiation. Conclusions Subchondral bone ultrastructure change occurred at early stage of OA ahead of microscopic cartilage degeneration, which may further impair articular cartilage. It was possibly related to elevated level of osteoblast differentiation.
The crystallographic orientation of polycrystalline perovskites is found to be strongly correlated with their intrinsic properties; therefore, it can be used to effectively enhance the performance of ...perovskite‐based devices. Here, a facile way of manipulating the facet orientation of polycrystalline perovskite films in a controllable manner is reported. By incorporating a cross‐linkable organic ligand into the perovskite precursor solution, the crystal orientation disorder can be reduced in the resultant perovskite films to exhibit the prominent (001) orientation with a preferred stacking mode. Moreover, the as‐formed low‐dimensional perovskites (LDPs) between the organic ligand and the excess lead iodide can passivate the defects around the grain boundaries. Consequently, highly efficient p‐i‐n structured perovskite solar cells (PSCs) can be made in both rigid and flexible forms from modified perovskites to show high power conversion efficiencies (PCE) of 24.12% and 23.23%, respectively. The devices also exhibit superior long‐term stability in a humid environment (with T90 > 1000 h) and under thermal stress (retaining 87% of its initial PCE after 1000 h). More importantly, the ligand enables the derived LDPs to be crosslinked (under 254 nm UV illumination) to demonstrate excellent mechanical bending durability in flexible devices.
A facile and controllable strategy is reported to manipulate the crystallographic orientation of polycrystalline perovskites by employing a cross‐linkable organic ligand. The resultant photovoltaic devices can achieve high power conversion efficiency and superior long‐term stability. Moreover, cross‐linked LDPs within 3D perovskites enable flexible devices with significantly enhanced bending durability.
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