Study on Nutritional Knowledge, Attitude and Behavior of Chinese School Football Players.

OBJECTIVE: This study aims to validate previous structural models of factors influencing dietary behavior changes and construct the knowledge, attitude, and behavioral models of youth school football players. METHODS: 279 school football players aged 12-17 years in Grades 7-12 in Hunan Province, China, completed a questionnaire to collect data on sports nutrition knowledge, attitudes, and behavior. A structural equation model (SEM) was built based on the knowledge-attitude-behavior (KAB) model and the theory of planned behavior (TPB) model to introduce nutritional knowledge directly or by altering attitudes into the dietary behavior path of players. Four factors affecting dietary behaviors were involved in the hypothetical structure, which consists of the following hypotheses: (1) nutrition knowledge affects the attitude towards sports nutrition (H1); (2) nutrition knowledge affects dietary behaviors (H2); (3) nutrition knowledge affects subjective norms (H3); (4) nutrition knowledge affects perceived behavioral control (H4); (5) subjective norms affect dietary behaviors (H5); and 6) perceived behavioral control affects dietary behaviors (H6). RESULTS: Confirmatory factor analysis (CFA) revealed that the reliability, convergent validity, and discriminant validity of the built SEM conformed to the measured relationships in each dimension. In the final structural model, it was found that nutrition knowledge had a direct impact on the attitudes of players and affected their dietary behaviors in a direct manner or through their subjective norms and perceived behavioral control. CONCLUSIONS: The results are in agreement with the TPB-based KAB chain and support the KAB theory for youth school football players in Hunan Province, China.

Mg2In3Si2P7: A Quaternary Diamond-like Phosphide Infrared Nonlinear Optical Material Derived from ZnGeP2.

Balancing the second-harmonic generation (SHG) coefficient, band gap, and birefringence is a vital but addressable challenge for designing infrared nonlinear optical materials. By applying a "rigidity-flexibility coupling" strategy, a quaternary diamond-like phosphide, Mg2In3Si2P7, with wurtzite-type superstructure was successfully designed and synthesized. Remarkably, it achieved the rare coexistence of giant second-harmonic generation (2 × ZnGeP2 and 7.1 × AgGaS2), suitable band gap (2.21 eV), moderate birefringence (0.107), and wide IR transparent range (0.56-16.4 µm). First-principles calculations revealed that the giant SHG response and large birefringence can be attributed to the synergy of arrangement-aligned [InP4] and [SiP4] tetrahedra. This work not only opens a new avenue for designing advanced infrared nonlinear optical materials but also may spur more explorations on quaternary diamond-like pnictides.

The effects of the measures against COVID-19 pandemic on physical activity among school-aged children and adolescents (6-17 years) in 2020: A protocol for systematic review.

BACKGROUND: The pandemic of coronavirus disease (COVID-19) has greatly changed people's daily lives, forcing countries to take actions, such as school shutdown, lockdown, isolation, and social distancing measures. It remains unclear how the closures, cancellations, and restrictions of schools and courses as a response to the COVID-19 pandemic affect the engagement of school-aged children and adolescents in relation to physical activity (PA). METHODS: The articles in the databases of EBSCO (including AMED, CINAHL Plus, Health Business, Health Source MEDLINE with Full Text, APA PsycArticles, APA PsycINFO, and SPORTDiscus) published during the period from 1 January 2020 to 31 December 2020 will be retrieved, and the data in the selected articles are extracted, including research methods, demographics, and key results. Search outcomes were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The Mixed Methods Appraisal Tool (MMAT) will be used to evaluate research quality. Two reviewers are responsible for completing the three tasks, namely selecting the articles that meet the inclusion criteria, extracting data in the articles selected, and evaluating their research quality. All findings, and especially primary outcomes will be summarized in a table format of findings. The results will provide a high-quality synthesis of current evidence for researchers in this subject area. AIM: The objective of this systematic review is to investigate the effects of the COVID-19 pandemic on PA in children and adolescents aged 6-17 years during 2020. 1). What impact has the COVID-19 pandemic had on PA levels in school-aged children and adolescents? 2). Investigating changes in the locations of school-aged children's and adolescents' PA between the pre-COVID-19 period (January 2020) and the COVID-19 period (December 2020). RESULTS: We hope that this study will provide government authorities and health professionals with the necessary information in guiding actions and allocating resources, so that the situation of physical inactivity in school-aged children and adolescents during the COVID-19 pandemic can be improved, thereby enhancing their physical health. PROTOCOL REGISTRATION NUMBER: This review was submitted and registered under CRD42020225976 in PROSPERO.

α-Ca2CdP2 and ß-Ca2CdP2: Two Polymorphic Phosphide-Based Infrared Nonlinear Crystals with Distorted NLO-Active Tetrahedral Motifs Realizing Large Second Harmonic Generation Effects and Suitable Band Gaps.

Two polymorphic phosphide-based infrared (IR) nonlinear optical (NLO) crystals, α-Ca2CdP2 and ß-Ca2CdP2, were obtained by combining alkaline-earth metals and d10 transition metals using metal flux and metal salt flux methods, respectively. The crystal structure of α-Ca2CdP2 is orthorhombic in the space group Cmc21 (no. 36), while the structure of ß-Ca2CdP2 is monoclinic in the space group Cm (no. 8). Both are two-dimensional layered structures that are composed of CdP4 tetrahedra layers via sharing vertices, which stack along the b-axis and the c-axis, respectively. The second harmonic generation (SHG) measurements manifest that α-Ca2CdP2 and ß-Ca2CdP2 exhibit strong SHG intensities (1.41 and 3.28× that of AgGaS2 at a 2050 nm laser, respectively). Other optical measurements indicate that α-Ca2CdP2 and ß-Ca2CdP2 have suitable band gaps (1.98 and 1.55 eV, respectively), high laser-induced damage thresholds (4.5 and 3.1× that of AgGaS2 at 1064 nm laser, respectively) and appropriate birefringence (0.12 and 0.20 at 2050 nm, respectively) in addition to covering wide infrared transparent regions. The research on α-Ca2CdP2 and ß-Ca2CdP2 demonstrates that they are potential IR NLO candidates. Theoretical calculations uncover that their SHG effects are from distorted CdP4 tetrahedra, highlighting that tetrahedral motifs, including d10 transition metals, would be ideal NLO-active building blocks.

Anionic Aliovalent Substitution from Structure Models of ZnS: Novel Defect Diamond-like Halopnictide Infrared Nonlinear Optical Materials with Wide Band Gaps and Large SHG Effects.

To design pnictide nonlinear optical materials with wide band gap and large second-harmonic generation, the heavy halogen I was introduced into pnictides through anionic aliovalent substitution with diamond-like ZnS as templates. Thus, four excellent halopnictide-based infrared nonlinear optical crystals, MII 3 PnI3 (MII =Zn, Cd; Pn=P, As), were obtained. They all exhibited defect diamond-like structures with highly parallel-oriented [MII PnI3 ] mixed-anionic tetrahedral groups, leading to excellent physical properties including wide band gaps (2.38-2.85 eV), large second harmonic generation responses (2.7-5.1×AgGaS2 ), high laser-induced damage thresholds (5.5-10.7×AgGaS2 ), and good IR transparency. In particular, Cd3 PI3 and Cd3 AsI3 achieved phase-matching (Δn=0.035 and 0.031) that their template ß-ZnS could not do. Anionic aliovalent substitution provides a feasible strategy to design novel promising halopnictide IR NLO materials.