Longitudinal Extension of Double π-Helix Enables Near-Infrared Amplified Dissymmetry and Chiroptical Response.

Near-infrared (NIR) circularly polarized light absorbing or emitting holds great promise for highly sensitive and precise bioimaging, biosensing, and photodetectors. Aiming at designing NIR chiral molecular systems with amplified dissymmetry and robust chiroptical response, herein, we present a series of double π-helical dimers with longitudinally extended π-entwined substructures via Ullmann or Yamamoto homocoupling reactions. Circular dichroism (CD) spectra revealed an approximate linear bathochromic shift with the rising number of naphthalene subunits, indicating a red to NIR chiroptical response. Particularly, the terrylene diimide-entwined dimers exhibited the strongest CD intensities, with the maximal |Δε| reaching up to 393 M-1 cm-1 at 666 nm for th-TDI[2]; and a record-high chiroptical response (|ΔΔε|) between the neutral and dianionic species of 520 M-1 cm-1 at 833 nm for th-TDI[2]Cl was achieved upon further reduction to its dianionic state. Time-dependent density functional theory (TDDFT) calculations suggested that the pronounced intensification of the CD spectra originated from a simultaneous enhancement of both electric (µ) and magnetic (m) transition dipole moments, ultimately leading to an overall increase in the rotatory strength (R). Notably, the circularly polarized luminescence (CPL) brightness (BCPL) reached 77 M-1 cm-1 for th-TDI[2]Cl, among the highest values reported for NIR-CPL emitters. Furthermore, all chiral dianions exhibited excellent air stability under ambient conditions with half-life times of up to 10 days in N-methylpyrrolidone (NMP), which is significant for future biological applications and chiroptic switches.

Enhancing Carrier Transport in 2D/3D Perovskite Heterostructures through Organic Cation Fluorination.

The interfacial 2D/3D perovskite heterostructures have attracted extensive attention due to their unique ability to combine the high stability of 2D perovskites with the remarkable efficiency of 3D perovskites. However, the carrier transport mechanism within the 2D/3D perovskite heterostructures remains unclear. In this study, the carrier transport dynamics in 2D/3D perovskite heterostructures through a variety of time-resolved spectroscopic measurements is systematically investigated. Time-resolved photoluminescence results reveal nanosecond hole transfer from the 3D to 2D perovskites, with enhanced efficiency through the introduction of fluorine atoms on the phenethylammonium (PEA) cation. Transient absorption measurements unveil the ultrafast picosecond electron and energy transfer from 2D to 3D perovskites. Furthermore, it is demonstrated that the positioning of fluorination on the PEA cations effectively regulates the efficiency of charge and energy transfer within the heterostructures. These insightful findings shed light on the underlying carrier transport mechanism and underscore the critical role of cation fluorination in optimizing carrier transport within 2D/3D perovskite heterostructure-based devices.

Predation Risk, and Not Shelter or Food Availability, as the Main Determinant of Reproduction Investment in Island Lizards.

Reproductive investment, including the number of offspring produced, is one of the fundamental characteristics of a species. It is particularly important for island vertebrates, which face a disproportionate number of threats to their survival, because it predicts, among other things, a species' resilience to environmental disruption. Taxa producing more offspring recover more quickly from environmental perturbations and survive environmental change better. However, ecologists do not understand which primary drivers shape a species' reproductive investment well. Here, we compare the reproductive efforts of 14 island populations of the Aegean Wall Lizard (Podarcis erhardii), which lives across widely diverging environmental conditions. We test three hypotheses, namely that reproductive investment (measured as clutch size, clutch volume) is (1) positively associated with predation risk ['Predation Risk Hypothesis']; (2) positively associated with the presence of reliable vegetation cover that provides shelter ['Gravid Female Protection Hypothesis']; and (3) limited by (and hence positively correlated with) food availability ['Food Limitation Hypothesis']. Although field data are somewhat consistent with all three hypotheses, statistical analyses provide strong support for the Predation Risk Hypothesis. The results not only shed light on which fundamental forces shape reproductive investment in island vertebrates, but can also help shape conservation priorities.

Characteristics and influencing factors of early childhood teachers' work stress and burnout: A comparative study between China, Ghana, and Pakistan.

Introduction: Many studies have documented the stress and burnout experienced by early childhood teachers. However, few have focused on comparisons among countries, particularly developing ones. Meanwhile, female teachers, who are more sensitive and tend to provide emotional responses, are often overlooked as a major force of emotional involvement. This study examined the similarities and differences of early childhood teachers' stress, burnout, and gender in China, Ghana, and Pakistan. Methods: This study adopted a cross-sectional design. The participants included 945 preschool and lower primary school teachers recruited from Zhejiang Province in China, the Ashanti Region in Ghana, and Punjab, Pakistan. The analyses were conducted using structural equation modeling. First, the study estimated all parameters separately and without constraints between the groups for all models. Second, the study compared the latent mean difference and of stressors and burnout between teachers' personal and job characteristics. Third, a structural equation model was used to assess the relationship between teachers' stressors and burnout. Results: Across the three countries, female teachers are more stressed out, with higher emotional demands and work-family conflicts, and are more prone to burnout with a greater level of emotional exhaustion and a lower level of personal accomplishments than their male counterparts are. Moreover, Chinese teachers were found to be the most stressed-out group with the highest level of burnout. In comparison to teachers in China and Pakistan, early childhood teachers in Ghana possess the lowest level of emotional demands. With the lowest level of emotional exhaustion and the highest level of personal accomplishments, Pakistani teachers were unlikely to experience burnout. Discussion: This study comparatively analyzed the characteristics of stress and burnout among ECTs in different cultural settings and educational systems in three developing countries (China, Ghana, and Pakistan), and revealed workplace characteristics and circumstances for ECTs. In addition, this study takes gender as the main influencing factor and explores its effect on ECTs' stress and burnout, and it highlights and verifies "emotionality" in ECTs' profession. As a result, policymakers and stakeholders in different countries may be encouraged to improve ECE quality and the well-being of ECTs.

Blood Donation Fear, Perceived Rewards, Self-Efficacy, and Intention to Return Among Whole Blood Donors in China: A Social Cognitive Perspective.

With the increasing demand from aging population and seasonal blood shortage, recruiting and retaining blood donors has become an urgent issue for the blood collection centers in China. This study aims to understand intention to donate again from a social cognitive perspective among whole blood donors in China through investigating the association between the blood donation fear, perceived rewards, self-efficacy, and intention to return. A cross-sectional survey was conducted in six cities, which are geographically and socioeconomically distinct areas in Jiangsu, China. Respondents completed a self-administrated questionnaire interviewed by two well-trained medical students. A total of 191 blood donors were included in the current study. Descriptive analysis, correlation analysis, and a generalized linear regression model were used to explore the association between demographic characteristics, psychological factors, and intention to donate again. After controlling other covariates, donors with higher fear scores reported lower intention to return (p = 0.008). Association between self-efficacy and intention to return was statistically significant (p < 0.001), whereas the association between intrinsic rewards (p = 0.387), extrinsic rewards (p = 0.939), and intention to return were statistically insignificant. This study found that either intrinsic rewards or extrinsic rewards are not significantly associated with intention to donate again among whole blood donors in China, and fear is negatively associated with intention to donate again. Therefore, purposive strategies could be enacted beyond appeals to rewards and focus on the management of donors' fear.

PDL and CD insensitive low complexity equalizer for short reach coherent systems.

We propose a polarization dependent loss (PDL) and chromatic dispersion (CD) insensitive, low-complexity adaptive equalizer (AEQ) for short-reach coherent optical transmission systems. The AEQ contains a 1-tap butterfly finite impulse response (FIR) filter and two N-tap FIR filters. It first performs polarization demultiplexing using the 1-tap filter, of which the coefficients are obtained based on Stokes space. Then it mitigates the inter-symbol interference (ISI) using the two N-tap finite impulse response (FIR) filters and adjust the filter's coefficients by utilizing constant modulus algorithm (CMA). Through theoretical and experimental analysis, we verify that this proposed AEQ can perform robust polarization demultiplexing when PDL and CD exists. Besides, our proposed AEQ has faster convergence speed compared with recently proposed AEQs. In addition, it reduces the number of multipliers and thus reduce the computational complexity of conventional butterfly filter structure AEQ. And this proposed AEQ suffers little bit error ratio loss compared with the conventional AEQ. Due to the low-complexity and robustness to PDL and CD, this proposed AEQ is well-suited for future low-cost short-reach optical communication system.

Loss weight adaptive multi-task learning based optical performance monitor for multiple parameters estimation.

A loss weight adaptive multi-task learning based artificial neural network (MTL-ANN) is applied for joint optical signal-to-noise ratio (OSNR) monitoring and modulation format identification (MFI). We conduct an experiment of polarization division multiplexing (PDM) coherent optical system with 5 km standard single mode fiber (SSMF) transmission to verify this monitor. A group of modulation schemes including nine modulation adaptive M-QAM formats are selected as the transmission signals. Instead of circular constellation, signals' amplitude histograms after constant module algorithm (CMA) based polarization de-multiplexing are selected as input features for our proposed monitor. The experimental results show that the MFI accuracy reaches 100% in the estimated OSNR range. Furthermore, when treated as regression problem and classification problem, OSNR estimation with a root mean-square error (RMSE) of 0.68 dB and an accuracy of 98.7% are achieved, respectively. Unlike loss weight fixed MTL-ANN, loss weight adaptive MTL-ANN could search the optimal loss weight ratio automatically for different link configurations. Besides that, the number of estimated parameters can be easily expanded, which is attractive for multiple parameters estimation in future heterogeneous optical networks.

Intelligent optical performance monitor using multi-task learning based artificial neural network.

An intelligent optical performance monitor using multi-task learning based artificial neural network (MTL-ANN) is designed for simultaneous OSNR monitoring and modulation format identification (MFI). Signals' amplitude histograms (AHs) after constant module algorithm are selected as the input features for MTL-ANN. The results obtained from simulation and experiment of NRZ-OOK, PAM4 and PAM8 signals demonstrate that MTL-ANN could achieve OSNR monitoring and MFI simultaneously with higher accuracy and stability compared with single-task learning based ANNs (STL-ANNs). The results show an MFI accuracy of 100% for the three modulation formats under consideration. Furthermore, OSNR monitoring with mean-square error (MSE) of 0.12 dB and accuracy of 100% is achieved while regarding it as regression problem and classification problem, respectively. In this intelligent optical performance monitor, only a single MTL-ANN is deployed, which enables reduced-complexity optical performance monitor (OPM) devices for multi-parameters estimation in future heterogeneous optical network.

The association of DNA methyltransferase 1 gene polymorphisms with susceptibility to childhood acute lymphoblastic leukemia.

BACKGROUND: It has been suggested that aberrant DNA methylation is a common epigenetic alteration in malignancies. Genetic variations in DNA methyltransferase 1 gene (DNMT1), which encodes the maintenance methyltransferase, have been demonstrated to be involved in cancer susceptibility. In the present study, we investigated whether genetic polymorphisms in DNMT1 could be associated with risk of childhood acute lymphoblastic leukemia (ALL) in a Chinese population. METHODS: We selected seven tagging single-nucleotide polymorphisms (tagSNPs, rs11880388, rs10423341, rs7253062, rs11085721, rs2228611, rs2228612 and rs16999593) in DNMT1 and genotyped these SNPs by using TaqMan method in a case-control study of 377 patients with ALL and 500 healthy controls. The logistic regression was used to assess the genetic associations with occurrence of ALL with adjustment for possible confounders. RESULTS: We found that one (rs11085721) of the seven tagSNPs was significantly associated with the risk of ALL. Compared with individuals' with DNMT1 rs11085721 GG genotype, those subjects carrying the rs11085721 GT genotypes were associated with significantly increased risk for ALL (GT vs. GG:OR=1.29, 95% CI=1.10-1.51). Similar association was also observed when combined the individuals with rs11085721 GT and rs11085721 TT genotypes (GT/TT vs. TT:OR=1.29, 95% CI=1.10-1.50). No positive results were observed for the other tagSNPs. CONCLUSIONS: Our results suggest that the DNMT1 rs11085721 polymorphism may confer susceptibility to ALL in the Chinese population. The initial findings should be validated by large population-based prospective studies in the future.

[Development of standardization platform for optical density value based on an improved method].

Due to the high variation in test results of indirect enzyme-linked immuno sorbent assay (ELISA) and complicated steps involved in the process of standardization, a platform used for standardizing the test results from indirect ELISA was developed. The platform was designed based on 'Improved Standardization Method for Optical Density' (I-STOD). Gauss-Newton iteration was applied to estimate parameters in a standard formula. Programming Language VB was used for developing interface of platform. The results indicated that the validity of experiment could be verified through platform. A well determined scope of standardization could be generated. The sample with concentration within the scope was standardized and the degree of dilution was calculated for those outside the scope. The platform was successfully developed which normalized the process of standardization. The function provides the researchers with an effective and convenient tool for quickly achieving standardization of ELISA test results.