And it is widely accepted that its photoluminescence (PL) emission is originated from the radiative transition between conduction band (CB), contributed by the π antibonding orbitals (π*) or δ* related to the sp 2 CN bond and valence band (VB) predominated by the lone pair (LP) in the edge N 2p orbitals. [3] Based on that the PL emission of g-C 3 N 4 in the region of 430-450 nm and 450-500 nm are ascribed to δ*→LP and π*→LP transition, respectively, the PL emission band can be controlled by adjusting π-conjugated polymeric network structure, the size of sp 2 CN clusters, layer packing, and defect degree. [4] However, pristine g-C 3 N 4 had low quantum yield (QY) and narrow range of PL emission (430-550 nm) due to its stable electronic band structure, [5] showing only slight changes in bandgaps upon different condensation precursors and reaction parameters (2.58-2.87 eV). [6] Over a decade, various functionalization strategies (including structural manipulation, [7] atomic/molecular doping, [8] and heterojunction construction [9] ) devoted to the electronic band structure adjustment, mainly aiming for the improvement of g-C 3 N 4 -related catalysis by enhancing their solar light (450-650 nm) is synthesized through the one-step molecular doping during the thermal condensation process of g-C 3 N 4 conjugated framework, which opens up its application beyond the conventional catalysis scopes. By adjusting the doped content of heteromolecules, the modified g-C 3 N 4 with the optical properties controlled according to the demand of practical applications can be facilely and largely obtained. It overcomes the limitation of the narrow adjusting range of conventional g-C 3 N 4 on optical properties and makes it become more promising for applications in solid-state displays. The corresponding multiple-color g-C 3 N 4 -based LED devices and the white-light LEDs with high quality can be obtained as supported by experiments and theoretical calculations. Moreover, the effect of doped molecule on the π-conjugated system of g-C 3 N 4 is systematically studied here, and the tunable luminescence mechanism is proposed. Polymeric g-C 3 N 4 with controllable photoluminescence emission wavelength in the whole visible light range Full-Color PhotoluminescenceThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.
Background As the birth policy has been adjusted from one-child-one-couple to universal two-child-one-couple in China, there is an increasing number of women undergoing a second pregnancy after a previous cesarean section (CS). Undertaking an elective repeat CS (ERCS) has been taken for granted and has thus become a major contributor to the increasing CS rate in China. Promoting trial of labor after CS (TOLAC) can reduce the CS rate without compromising delivery outcomes. This study aimed to investigate Chinese obstetricians’ perspectives regarding TOLAC, and the factors associated with their decision-making regarding recommending TOLAC to pregnant women with a history of CS under the two-child policy. Methods A cross-sectional survey was carried out between May and July 2018. Binary logistic regression was used to determine the factors associated with the obstetricians’ intention to recommend TOLAC to pregnant women with a history of CS. The independent variables included sociodemographic factors and perceptions regarding TOLAC (selection criteria for TOLAC, basis underlying the selection criteria for TOLAC, and perceived challenges regarding promoting TOLAC). Results A total of 426 obstetricians were surveyed, with a response rate of ≥83%. The results showed that 31.0% of the obstetricians had no intention to recommend TOLAC to pregnant women with a history of CS. Their decisions were associated with the perceived lack of confidence regarding undergoing TOLAC among pregnant women with a history of CS and their families (odds ratio [OR] = 2.31; 95% CI: 1.38–1.38); obstetricians’ uncertainty about the safety of TOLAC for pregnant women with a history of CS (OR = 0.49; 95% CI: 0.27–0.96), and worries about medical lawsuits due to adverse delivery outcomes (OR = 0.14; 95% CI: 0.07–0.31). The main reported challenges regarding performing TOLAC were lack of clear guidelines for predicting or avoiding the risks associated with TOLAC (83.4%), obstetricians’ uncertainty about the safety of TOLAC for women with a history of CS (81.2%), pregnant women’s unwillingness to accept the risks associated with TOLAC (81.0%) or demand for ERCS (80.7%), and the perceived lack of confidence (77.5%) or understanding (69.7%) regarding undergoing TOLAC among pregnant women and their families. Conclusion A proportion of Chinese obstetricians did not intend to recommend TOLAC to pregnant women with a history of CS. This phenomenon was closely associated with obstetricians’ concerns about TOLAC safety and perceived attitudes of the pregnant women and their families regarding TOLAC. Effective measures are needed to help obstetricians predict and reduce the risks associated with TOLAC, clearly specify the indications for TOLAC, improve labor management, and popularize TOLAC in China. Additionally, public health education on TOLAC is necessary to improve the understanding of TOLAC among pregnant women with a history of CS and their families, and to improve their interactions with their obstetricians regarding shared decision making.
The application of graphitic carbon nitride (g‐C3N4) has been restricted in some optoelectronics fields due to its narrow tunable emission region. In order to engineer the optical properties, herein we combine Eu3+:Y2O3 nanocrystals with g‐C3N4to control its electronic structure. Surprisingly, with the increasing concentration of Eu3+:Y2O3 nanocrystals, the photoluminescence of Eu3+:Y2O3/g‐C3N4 (EYCN) showed a continuous red shift in comparison with pure g‐C3N4 from blue to green. In EYCN composites, the Eu3+:Y2O3 nanocrystals as electron donors, can improve the degree of electron delocalization and narrow the bandgap. Importantly, the EYCN composites not only maintain the intrinsic blue‐green emission of g‐C3N4, but also introduce the red light of Eu3+ ions. Based on the EYCN composites, white light‐emitting diode (WLED) were fabricated with a Commission International de L’Eclairage value of (0.3631, 0.3560). This work proposes a new kind of luminescent g‐C3N4‐based composites, which is expected to broaden its applications in optoelectronics field.
BackgroundExtrauterine growth restriction among the very-low birth weight preterm infants (VLBWPIs) is associated with poorer cognitive development outcome, while the rapid weight gain in infancy increases the long-term risk of obesity and noncommunicable disease among VLBWPIs. However, the results of research on the association between early postnatal growth velocity and neurodevelopmental outcomes in VLBWPIs are still limited and controversial.ObjectiveWe aimed to explore the association between the growth velocity in early postnatal and neurodevelopmental impairment (NDI) among VLBWPIs.MethodsThis study was a secondary analysis of a previously published prospective cohort. It was based on data on 1,791 premature infants with a birth weight of less than 1500 g, registered in the database of the Premature Baby Foundation of Taiwan between 2007 and 2011. A binary logistic regression model was used to evaluate the association between the weight gain velocity in different periods [from birth to 6 months corrected age (CA), 6 to 12 months CA, and 12 to 24 months CA] and NDI, respectively. The generalized additive model and the smooth curve fitting (penalized spline method) were used to address nonlinearity, and a two-piece-wise binary logistic regression model was added to explain the nonlinearity further.ResultsNonlinearities were observed between NDI and the weight gain velocity from birth to 6 months CA [inflection point 20.36, <inflection point: odds ratio (OR) = 0.75, 95% confidence interval (CI) 0.67–0.84, >inflection point: OR = 1.01, 95% CI 0.97–1.05], 6–12 months CA [inflection point 9.44, <inflection point: OR = 0.89, 95% CI 0.84–0.94, >inflection point: OR = 1.05, 95% CI 1.05–(1.00, 1.11)], and 12–24 months CA [inflection point 16.00, <inflection point: OR = 0.93, 95% CI 0.88–0.98, >inflection point: OR = 1.75, 95% CI 1.05–(0.96, 3.08)].ConclusionThe neurodevelopmental benefits from a rapid weight gain velocity from birth to 24 months CA might be limited once the growth pace reaches an optimum level. It would help find a pattern of growth that facilitates optimal neurodevelopment, yet minimizes negative health consequences associated with overnutrition further.
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