Manipulating upconversion luminescence intensity in a single crystal particle with a waveguide structure.

Lanthanide (Ln)-doped upconversion luminescence (UCL) materials have attracted worldwide attention due to their unique photophysical characteristics. However, how to effectively improve their UCL efficiency has always been an important scientific issue. Here, we design and fabricate ß-NaYF4 microtubes (MTs) with a natural hexagonal shape in the cross section and wedge shape on both top vertexes, which can be regarded as an optical waveguide. The UCL property of a single ß-NaYF4:Yb3+,Er3+(or Tm3+) MT is systematically investigated based on waveguide-excitation modes. It is found that the excitation light can be efficiently coupled in the ß-NaYF4:Yb3+,Er3+(or Tm3+) MT by modulating the angle between the wedge-shape end plane of MT and the microscope slide. In addition, it is clearly observed that the excitation light can be confined and propagate in the MT by introducing a 633 nm laser, which is mainly due to the natural waveguide structure with a stronger confinement and propagation effect of light, thereby enhancing light-to-MT interactions. The current work provides a powerful solution to build high-efficiency Ln-doped UCL materials, which may have potential applications in the optical communication and biomedical fields.

Tied Infections: How Social Connectedness to Other COVID-19 Patients Influences Illness Severity.

Expanding on recent research on the transmission of COVID-19 via social networks, this article argues that exposure to familial and other close contacts who already have the disease may increase the severity of one's subsequent illness. We hypothesize that having family members or close contacts who were diagnosed with COVID-19 before one's own diagnosis exacerbates illness severity due to several potential mechanisms including changes in available social support access, increased stress and strain, and increased viral load due to the nature of one's exposure to the novel coronavirus. We analyze administrative data of all 417 patients who were diagnosed with COVID-19 in the Chinese city of Shenzhen between January 8 and February 25, 2020. Our analyses show that, when patients had family members or close ties diagnosed with COVID-19, they experienced more severe illness. We also find that patients with infected family members or close contacts did not have significantly extended total illness duration, due to their reduced time to diagnosis. The implications of both findings are discussed.

Tunable broadband circular polarizer based on ultrahigh-order surface plasmonic resonance.

Circular polarizers have potential applications in optical communication and liquid crystal display. In this paper, a multilayer twisted nanoring-rod nanostructure is designed. The finite element method is used to explore the surface plasmon of the structure under the excitation of left-handed circularly polarized light and right-handed circularly polarized light. The results show that the structure can be used as a polarizer in the tunable operating bandwidth of 400-1290 nm, and tunability is achieved by changing the filling medium near the structure instead of the geometric parameters of the nanostructures. We qualitatively reveal the physical mechanism of this phenomenon from the perspective of plasmon resonance coupling by plotting the charge distribution at several specific wavelengths.

Racial-ethnic, gender identity, and sexual orientation disparities in COVID-19-related social and health outcomes: A decomposition analysis.

Despite the growing literature on racial-ethnic disparities during the pandemic, less is known about the explanatory mechanisms of these disparities and inequalities across other axes, such as gender and sexual identities. We studied the levels and sources of racial-ethnic, gender identity, and sexual minority disparities in social (i.e., unmet resource needs) and health (i.e., hospitalization) outcomes among individuals diagnosed with COVID-19, hypothesizing differential age structure, underlying health, and work and living arrangements as contributors to inequalities. Using large-scale administrative data from Chicago and adjusting for covariates, we found substantial racial-ethnic and gender identity disparities in both outcomes, and weak evidence of sexual minority disparities in unmet needs. Subsequent decomposition analyses revealed that living in larger households, having a higher share of non-adult cases, and facing higher burdens of chronic illness, obesity, and unemployment each statistically significantly drove racial-ethnic disparities in unmet needs, but these together explained less than 15% of the disparities. Similarly, about 20% of the Black-White gap in hospitalization resulted from disparities in underlying health and unemployment, whereas a higher proportion of non-adult cases or higher unemployment rates respectively proved the only significant pathways to partially explain transgender individuals' disadvantages in unmet needs (12%) or hospitalization (6%). These findings highlight the importance of considering multiple dimensions of social differences in studying health disparities, the vulnerabilities of transgender and non-adult communities during the pandemic, and the valid yet quite limited roles of previously suggested sociodemographic factors in accounting for COVID-19-related categorical inequalities.

Preparation of a Three-Dimensional Composite Structure Based on a Periodic Au@Ag Core-Shell Nanocube with Ultrasensitive Surface-Enhanced Raman Scattering for Rapid Detection.

The absorption and scattering frequencies of surface plasmon resonance can be selectively adjusted by changing the morphology, size, structure, arrangement, and gap between noble metal nanoparticles so that the local electromagnetic field on the substrate surface can be further enhanced. This change will promote and popularize surface-enhanced Raman spectroscopy. This paper reports the research results and improvement scheme of surface enhanced Raman scattering (SERS) activity of silver-coated gold nanocubed/organism (Au@Ag/CW NCs) prepared by three-phase self-assembly. In the experiment, the uppermost oil phase in the three-phase self-assembly process was optimized as ethanol and n-hexane solution containing a specific concentration of a probe molecule rhodamine 6G or aspartame. The probe molecules were directly self-assembled on the surface of the composite substrate to avoid the possible loss and pollution during immersion and preservation and achieve the purpose of rapid detection. The results show that the Au@Ag/CW NC array substrate is a periodic cubic ring structure. The sensitivity, uniformity, reproducibility, and stability of composite Au@Ag/CW NC array substrates are verified by comparing the Raman activities of various substrates. The feasibility of using the substrate to realize rapid SERS detection, compared with the advantages and disadvantages of the traditional soaking method, proved that the prepared substrate and improvement direction have excellent potential for application and development prospects in the field of rapid food additive detection.

Social network influences on new mothers' infant sleep adjustments.

Despite public awareness campaigns, some parents continue to engage in infant sleep practices that are considered risky by health experts, such as bedsharing or placing their infants on their stomachs. This study examines the role their social networks play in shaping parents' responsiveness to new information and/or suggestions about how they should place their infants for sleep, paying attention to the respective effects of health professionals and their close interpersonal ties. We collected data from a sample of 323 new mothers in Washington, D.C., who described their infant sleep practices and perceived personal social networks. We find evidence that mothers' social networks play a significant role in the likelihood that they adjust their infant sleep practices within the first few months of their infants' lives. Mothers are more likely to change sleep practices when health professionals and/or (lay) family members advise them to do so. The influence of network members is not always positive. For mothers who initially follow safe practices, their probability of change increases if their network members substantially espouse unsafe practices. Among mothers with initially unsafe practices, network members' level of support for safe sleep practices is not predictive of the likelihood of sleep practice change. Implications for potential interventions are discussed.

Impact of Personal Social Network Types on Breastfeeding Practices in United States-Born Black and White Women.

Background: An individual's personal social network influences behavior; one is more likely to adopt behaviors consistent with norms within the network to avoid social stigma. Personal social network types, which are associated with individual behaviors, have been identified for new mothers: exclusive (kin centric) and expansive (not kin centric). Objective: To analyze the impact of personal social network type on breastfeeding practices in U.S.-born Black and White mothers. Methods: Mothers of infants <6 months old completed surveys about their personal social networks and feeding practices. Multinomial logit models examined how social network types moderated effects of sociodemographic factors on feeding practices. Results: Of 402 mothers, 67% self-identified as Black and 33% as White. Forty-six percent were exclusively breastfeeding; 26% were mixed breast and formula feeding. The likelihood of exclusively breastfeeding was positively associated with percentage of network members who had breastfed; this association was stronger for mothers with exclusive networks than those with expansive networks (ß = 2.74, p < 0.001 versus ß = 1.78, p = 0.03). Black race was positively correlated with exclusive breastfeeding or mixed feeding for mothers with exclusive networks (ß = 1.50, p = 0.046; ß = 1.86, p = 0.02, respectively). Lower educational level was negatively correlated with exclusive breastfeeding; this correlation was stronger for mothers with exclusive networks (ß = -1.91, p = 0.002 versus ß = -1.70, p = 0.04). Lower educational level was also negatively correlated with mixed feeding for mothers with exclusive networks (ß = -1.61, p = 0.02). Conclusions: Mothers' personal social network type likely moderates the relationship between sociodemographic variables and feeding practices. While the influence of having network members with breastfeeding experience is important, the magnitude of influence is stronger in exclusive networks.