Abstract
Predictable stereoselective formation of supramolecular assembly is generally believed to be an important but complicated process. Here, we show that point chirality of a ligand decisively ...influences its supramolecular assembly behavior. We designed three closely related chiral ligands with different point chiralities, and observe their self-assembly into europium (Eu) tetrametallic tetrahedral cages. One ligand exhibits a highly diastereoselective assembly into homochiral (either ΔΔΔΔ or ΛΛΛΛ) Eu tetrahedral cages whereas the two other ligands, with two different approaches of loosened point chirality, lead to a significant breakdown of the diastereoselectivity to generate a mixture of (ΔΔΔΔ and ΛΛΛΛ) isomers. The cages are highly emissive (luminescence quantum yields of 16(1) to 18(1)%) and exhibit impressive circularly polarized luminescence properties (|
g
lum
|: up to 0.16). With in-depth studies, we present an example that correlates the nonlinear enhancement of the chiroptical response to the nonlinearity dependence on point chirality.
Novel reassortant avian influenza H7N9 virus and pandemic 2009 H1N1 (H1N1pdm) virus cause human infections, while avian H7N2 and swine H1N1 virus mainly infect birds and pigs, respectively. There is ...no robust in vitro model for assessing the infectivity of emerging viruses in humans. Based on a recently established method, we generated long-term expanding 3D human airway organoids which accommodate four types of airway epithelial cells: ciliated, goblet, club, and basal cells. We report differentiation conditions which increase ciliated cell numbers to a nearly physiological level with synchronously beating cilia readily discernible in every organoid. In addition, the differentiation conditions induce elevated levels of serine proteases, which are essential for productive infection of human influenza viruses and low-pathogenic avian influenza viruses. We also established improved 2D monolayer culture conditions for the differentiated airway organoids. To demonstrate the ability of differentiated airway organoids to identify human-infective virus, 3D and 2D differentiated airway organoids are applied to evaluate two pairs of viruses with known distinct infectivity in humans, H7N9/Ah versus H7N2 and H1N1pdm versus an H1N1 strain isolated from swine (H1N1sw). The human-infective H7N9/Ah virus replicated more robustly than the poorly human-infective H7N2 virus; the highly human-infective H1N1pdm virus replicated to a higher titer than the counterpart H1N1sw. Collectively, we developed differentiated human airway organoids which can morphologically and functionally simulate human airway epithelium. These differentiated airway organoids can be applied for rapid assessment of the infectivity of emerging respiratory viruses to human.
University brand (UniBrand) is a recent concept, and its theoretical modelling is still somewhat inadequate. This paper examines how perceived service quality affects UniBrand performance, UniBrand ...image and behavioural intention. Using an online student survey, the present study obtained 528 usable responses. The conceptual model was validated using structural equation modelling. The study makes an innovative theoretical contribution by establishing a relationship between experience-centric brand performance and brand image, and the antecedents and consequences of this link. In addition, student satisfaction and trust were demonstrated to mediate the relationship between perceived service quality, brand performance, brand image and behavioural intention in a higher education context. However, there were no moderating effects of gender or mode-of-study on the model, confirming that the model is invariant across these variables. Overall, this model suggests the importance of experience-centric service quality attributes and how they affect university branding strategies for sustained positive intentions.
Middle East respiratory syndrome coronavirus (MERS-CoV) infection caused severe pneumonia and multiorgan dysfunction and had a higher crude fatality rate (around 50% vs 10%) than SARS coronavirus ...(SARS-CoV) infection. To understand the pathogenesis, we studied viral replication, cytokine/chemokine response, and antigen presentation in MERS-CoV–infected human monocyte–derived macrophages (MDMs) versus SARS-CoV–infected MDMs. Only MERS-CoV can replicate in MDMs. Both viruses were unable to significantly stimulate the expression of antiviral cytokines (interferon α IFN-α and IFN-β) but induced comparable levels of tumor necrosis factor α and interleukin 6. Notably, MERS-CoV induced significantly higher expression levels of interleukin 12, IFN-γ, and chemokines (IP-10/CXCL-10, MCP-1/CCL-2, MIP-1α/CCL-3, RANTES/CCL-5, and interleukin 8) than SARS-CoV. The expression of major histocompatibility complex class I and costimulatory molecules were significantly higher in MERS-CoV–infected MDMs than in SARS-CoV–infected cells. MERS-CoV replication was validated by immunostaining of infected MDMs and ex vivo lung tissue. We conclusively showed that MERS-CoV can establish a productive infection in human macrophages. The aberrant induction of inflammatory cytokines/chemokines could be important in the disease pathogenesis.
The role of programming in computing education for children has grown rapidly in recent years with the proliferation of specially designed programming tools, which is grounded on Seymour Papert's ...theoretical work in Constructionism. Studies show that some children can develop computational thinking skills and practices with programming activities when learning with the tools through a well-design curriculum in elementary education (or primary education). However, existing studies may not completely address whether programming skills and computational thinking can be connected to the development of other generic skills, which are considered important to the learning and cognitive development of children. This study investigates the impact of programming on three learning competencies (creative thinking, critical thinking and problem solving) known as twenty-first century skills. The conceptual mapping between programming, computational thinking and the three learning competencies is presented. In a one-year intervention in a primary school, students were taught how to build interactive games through programming, and thus explored some basic computational thinking concepts in class. Our results show that children perceived a significant impact of programming on their learning competencies. Yet, the transferability of twenty-first century skills developed through computational thinking and programming may require a further study. Our study provides insights from children as primary respondents to help direct future research in the field of programming and computational thinking education and its potential impact on twenty-first century skills.
Synergistic cooperation of phosphorylation induced mesoporous structure and phosphate group over g-C3N4 enhanced the photocatalytic CO2 reduction. Display omitted
•MPCN was acquired via dialysis ...deacidifying and vacuum freeze drying processes.•MPCN showed enhanced solar-to-fuels conversion activity than bulk g-C3N4.•MPCN had higher carrier separation efficiency and better adsorption ability.
Mesoporous structure of graphitic carbon nitride (g-C3N4) has been proved to be very important for artificial photosynthesis. Phosphate (PO43−) group played an essential role in adenosine triphosphate (ATP) for natural photosynthesis. In this letter, mesoporous phosphorylated g-C3N4 (MPCN) was prepared from bulk g-C3N4 (BCN) by concentrated phosphoric acid post-treatment. Photocatalytic CO2 reduction results revealed that MPCN displayed a much higher activity than BCN. Brunauer-Emmett-Teller (BET) surface areas, time-resolved photoluminescence (PL) spectroscopy, photocurrent and electrochemical impedance (EIS) spectroscopy, and valence band XPS were used to explain the enhanced photocatalytic CO2 conversion performances. It was concluded that the synergistic cooperation of phosphorylation induced mesoporous structure and surface PO43− groups, and the higher photo-induced carrier separation efficiency of MPCN resulted in its enhanced photocatalytic activity for solar-to-fuels conversion over BCN.
{001} facet dominated BiOBr nanosheets are fabricated via a facile hydrothermal method in the presence of nitric acid without any organic additive and applied for CO2 photoreduction. The ...concentration of nitric acid easily regulates the thickness of the obtained BiOBr nanosheets. When employing concentrations of 0, 0.1, 0.5, 1 and 4 M nitric acid, the corresponding surface area and percentage of exposed {001} facets of BiOBr-0, BiOBr-0.1, BiOBr-0.5, BiOBr-1 and BiOBr-4 nanosheets significantly increase in sequence. BiOBr-0 nanosheets are incapable of converting CO2 into CO. However, BiOBr-0.1, BiOBr-0.5, BiOBr-1 and BiOBr-4 nanosheets show successively enhanced CO2 photoreduction performance. Surprisingly, they exhibit high selectivity for converting CO2 into CO with negligible generation of CH4. In particular, BiOBr-4 shows the highest CO production rate of 4.45 mu mol g-1 h-1 under simulated sunlight irradiation. The electronic structure analysis demonstrates that the conduction band minimum is significantly raised to endow BiOBr-4 with reduction power for CO2/CO conversion, in comparison with the incapability of BiOBr-0. The breakthrough in CO2 reduction of BiOBr-4 nanosheets is ascribed to the larger active surface area, higher electron transfer, more effective charge carrier separation and significantly raised reduction ability.
This pilot study investigated the patterns of video and internet gaming habits and the prevalence and correlates of gaming addiction in Hong Kong adolescents. A total of 503 students were recruited ...from two secondary schools. Addictive behaviors of video and internet gaming were assessed using the Game Addiction Scale. Risk factors for gaming addiction were examined using logistical regression. An overwhelming majority of the subjects (94%) reported using video or internet games, with one in six (15.6%) identified as having a gaming addiction. The risk for gaming addiction was significantly higher among boys, those with poor academic performance, and those who preferred multiplayer online games. Gaming addiction was significantly associated with the average time spent gaming per week, frequency of spending money on gaming, period of spending money on gaming, perceived family disharmony, and having more close friends. These results suggest that effective educational and preventative programs or strategies are needed.
Bismuth oxybromide (BiOBr) nanosheets with fully exposed {001} and {010} facets are synthesized via a facile hydrothermal method. Significant differences in photocatalytic inactivation towards ...Escherichia coli K-12 under visible light irradiation are found to be highly dependent on the dominantly exposed facets. In comparison with BiOBr with dominant {010}-facet (B010) nanosheets, BiOBr with dominant {001}-facet (B001) nanosheets exhibit remarkably higher photocatalytic activity in bacterial inactivation. This superior activity is ascribed to the more favorable separation and transfer of photogenerated electron-hole pairs as well as more oxygen vacancies of B001 nanosheets. Due to the faster production and further accumulation of &z.rad; O sub(2) super(-) and h super(+) within a short time, the VLD photocatalyst of B001 nanosheets can completely inactivate 10 super(7) colony forming unit (CFU) mL super(-1) (i.e. 7-log reduction) bacterial cells within 2 h; while only 1- and 6.5-log reductions of bacterial cells can be achieved within 2 and 6 h, respectively, by B010 nanosheets due to limited amounts of h super(+) and &z.rad; O sub(2) super(-) generated.
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