Microplastic Human Dietary Uptake from 1990 to 2018 Grew across 109 Major Developing and Industrialized Countries but Can Be Halved by Plastic Debris Removal

Microplastics (MPs), plastic particles smaller than 5 mm, are now a growing environmental and public health issue, as they are detected pervasively in freshwater and marine environments, ingested by organisms, and then enter the human body. Industrial development drives this environmental burden caused by MP formation and human uptake by elevating plastic pollution levels and shaping the domestic dietary structure. We map the MP human uptake across 109 global countries on five continents from 1990 to 2018, focusing on the world’s major coastlines that are affected by plastic pollution that affects the United Nations’ Sustainable Development Goals (SDGs): SDG 6 (Clean Water and Sanitation), SDG 14 (Life Below Water), and SDG 15 (Life on Land). Amid rapid industrial growth, Indonesia tops the global per capita MP dietary intake at 15 g monthly. In Asian, African, and American countries, including China and the United States, airborne and dietary MP uptake increased over 6-fold from 1990 to 2018. Eradicating 90% of global aquatic plastic debris can help decrease MP uptake by more than 48% in Southeast Asian countries that peak MP uptake. To reduce MP uptake and potential public health risks, governments in developing and industrialized countries in Asia, Europe, Africa, and North and South America should incentivize the removal of free plastic debris from freshwater and saltwater environments through advanced water treatment and effective solid waste management practices

Theoretical Insights into Monometallofullerene Th@C₇₆: Strong Covalent Interaction between Thorium and the Carbon Cage

Th@C₇₆ has been studied by density functional theory combined with statistical mechanics calculations. The results reveal that Th@<i>T</i>_<i>d</i>(19151)-C₇₆ satisfying the isolated pentagon rule possesses the lowest energy. Nevertheless, considering the enthalpy–entropy interplay, Th@<i>C</i>₁(17418)-C₇₆ with one pair of adjacent pentagons is thermodynamically favorable at elevated temperatures, which is reported for the first time. The bonding critical points in both isomers were analyzed to disclose covalent interactions between the inner Th and cages. In addition, the Wiberg bond orders of M–C bonding in different endohedral metallofullerenes (EMFs) were investigated to prove stronger covalent interactions of Th–C in Th-based EMFs

Theoretical Insight into Sc₂C₇₆: Carbide Clusterfullerene Sc₂C₂@C₇₄ versus Dimetallofullerene Sc₂@C₇₆

In terms of density functional theory in combination with a statistical thermodynamic method, we have investigated the Sc₂C₇₆ species including dimetallofullerenes Sc₂@C₇₆ and carbide clusterfullerenes Sc₂C₂@C₇₄. Two dimetallofullerenes, Sc₂@<i>C</i>_<i>s</i>(17490)-C₇₆ and Sc₂@<i>T</i>_<i>d</i>(19151)-C₇₆, possess the lowest relative energies but exhibit poor thermodynamic stability within the fullerene-formation region (500–3000 K). In contrast, four carbide clusterfullerene isomers, Sc₂C₂@<i>D</i>_3<i>h</i>(14246)-C₇₄, Sc₂C₂@<i>C</i>_2<i>v</i>(14239)-C₇₄, Sc₂C₂@<i>C</i>₂(13333)-C₇₄, and Sc₂C₂@<i>C</i>₁(13334)-C₇₄, have excellent thermodynamic stability when considering the temperature effect. The Sc₂C₂@<i>D</i>_3<i>h</i>(14246)-C₇₄ isomer, which satisfies the isolated-pentagon rule (IPR), was characterized by its crystallographic structure; however, the other three non-IPR structures with two pairs of pentagon adjacencies are predicted for the first time. In particular, Sc₂C₂@<i>C</i>₂(13333)-C₇₄ and Sc₂C₂@<i>C</i>₁(13334)-C₇₄ are linked by a single Stone–Wales transformation. Meanwhile, bonding critical points and Mayer bond orders in the four isomers were analyzed to disclose the unique interactions between the inner clusters and cages. Additionally, the structural characteristics, ¹³C and ⁴⁵Sc NMR chemical shifts, and IR spectra of the four stable isomers are introduced to assist experimental identification and characterization in the future

Regioselectivity of Sc₂C₂@<i>C</i>_3<i>v</i>(8)‑C₈₂: Role of the Sumanene-Type Hexagon in Diels–Alder Reaction

Recently, several experiments have demonstrated high chemical reactivity of the sumanene-type hexagon in Sc₂C₂@C₈₂. To further uncover its reactivity, the Diels–Alder reaction to all the nonequivalent C–C bonds of C₈₂ and Sc₂C₂@C₈₂ has been investigated by density functional theory calculations. For the free fullerene, the [5,6] bond 7 is the thermodynamically most favored, whereas the addition on the [6,6] bond 3 has the lowest activation energy. Diels–Alder reaction has no preference for addition sites in the sumanene-type hexagon. However, in the case of the endohedral fullerene, the [6,6] bond 19 in the special hexagon becomes the most reactive site according to both kinetic and thermodynamic considerations. Further analyses reveal that bond 19 in Sc₂C₂@C₈₂ exhibits the shortest bond length and third largest π-orbital axis vector. In addition, the LUMOs of bond 19 are also symmetry-allowed to interact with butadiene

Cycloaddition of Benzyne to Armchair Single-Walled Carbon Nanotubes: [2 + 2] or [4 + 2]?

The reaction mechanism and regioselectivity of cycloaddition reactions of benzyne to armchair single-walled carbon nanotubes were investigated with quantum chemical methods. The [2 + 2] cycloaddition reaction follows the diradical mechanism, whereas the [4 + 2] cycloaddition reaction adopts the concerted mechanism. More importantly, the [2 + 2] product is always more stable thermodynamically than the [4 + 2] ones, regardless of the diameter, while the [4 + 2] cycloaddition becomes kinetically more favored as the diameter goes up

Theoretical Insight into the Mechanism of Gold(I)-Catalyzed Rearrangement of 2‑Propargyl 2<i>H</i>‑Azirines to Pyridines

The title reaction is investigated in detail theoretically using density functional theory. After 5-<i>endo</i>-dig cyclization by nucleophilic attack, five possible pathways are taken into account in this work: direct ring expansion followed or accompanied by proton-transfer (paths A and B, respectively), 1,3-cationic migration (path C), proton-transfer before ring expansion (path D), and processing via a gold-nitrene (path E). Results indicate that the reaction would undergo the favored sequential pathway (path A) rather than other pathways. Moreover, the concerted mechanism (path B), which is designed to account for the selectivity of product in the experiment, would be unlikely in the reaction. The selectivity of product could be explained by the hindrance of ligand (<i>t</i>-BuXPhos) and the stability of the carbocation. Moreover, the binding energy of product complexes could account for the observed reaction rate

Quantum Chemical Insight into La₂C₉₆: Metal Carbide Fullerene La₂C₂@C₉₄ versus Dimetallofullerene La₂@C₉₆

A family of dilanthanum-containing endohedral metallofullerene La₂C_2<i>n</i> (<i>n</i> = 46–51) was synthesized recently. In the present work, a systematical investigation on La₂C₉₆ series including the carbide clusterfullerene form La₂C₂@C₉₄ and the conventional dimetallofullerene form La₂@C₉₆ was implemented by density functional theory, combined with statistical mechanics. Three isomers, i.e., La₂@D₂(191838)-C₉₆, La₂C₂@C_s(153479)-C₉₄, and La₂C₂@C₁(153491)-C₉₄ were disclosed to be thermodynamically stable at the temperature region of endohedral metallofullerene formation. La₂@D₂(191838)-C₉₆ is the prevailing isomer at low temperature, while La₂C₂@C_s(153479)-C₉₄ and La₂C₂@C₁(153491)-C₉₄ are the most and second-most abundant isomers at high temperature. Interestingly, the highest occupied molecular orbital (HOMO) of La₂C₂@C₁(153491)-C₉₄ is distributed on one pole of the cage, and the lowest unoccupied molecular orbital (LUMO) of this isomer is mainly located on the equator of the cage, which can facilitate synthesis of regioselective derivatives. This work will provide useful information for further experimental identification and application of La₂C₉₆

Theoretical Insights into the Metal–Nonmetal Interaction Inside M₂O@<i>C</i>_2<i>v</i>(31922)‑C₈₀ (M = Sc or Gd)

The metal–nonmetal interaction is complicated but significant in organometallic chemistry and metallic catalysis and is susceptible to the coordination surroundings. Endohedral metallofullerene is considered to be an excellent model for studying metal–nonmetal interactions with the shielding effect of fullerenes. Herein, with the detection of ScGdO@C80 in a previous mass spectrum, we studied the effects of metal atoms (Sc and Gd) on the metal–nonmetal interactions of the thermodynamically stable molecules M2O@C2v(31922)-C80 (M = Sc and Gd), where metal atoms M can be the same or different, using density functional theory calculations. The inner metal atom and the fullerene cage show mainly ionic interactions with some covalent character. The Sc atom with higher electronegativity plays a greater important role in the metal–nonmetal interactions than the Gd atom. This study would be useful for the further study of the metal–nonmetal interaction

Table_1_The relationship between achievement motivation and college students’ general self-efficacy: A moderated mediation model.xlsx

ObjectiveThis study focused on the relationship between achievement motivation and college students’ general self-efficacy, and aimed to explore the mechanism of action between achievement motivation and general self-efficacy.MethodsThrough convenience sampling, 1,076 college students were investigated from Anhui Province in China. Achievement motivation, general self-efficacy, perceived social support, and sports participation were evaluated using standard scales. For data analysis, Pearson’s correlation analysis, structural equation model test, and bias-corrected percentile Bootstrap method were carried out.ResultsCommon method biases can be accepted in this study. (1) Achievement motivation can directly affect general self-efficacy and make a positive prediction; (2) Perceived social support plays a mediating role between achievement motivation and general self-efficacy, that is, achievement motivation can indirectly affect general self-efficacy through perceived social support; (3) Sports participation plays a moderating role in the first half of the mediating path of “achievement motivation → perceived social support → general self-efficacy.” The interaction between achievement motivation and sports participation affects perceived social support, and then indirectly affects general self-efficacy. In this moderated mediation model, The predictive effect of achievement motivation on perceived social support is significantly different among individuals with different levels of sports participation.ConclusionPerceived social support plays a part of mediating role between achievement motivation and college students’ general self-efficacy, which is moderated by sports participation.</p

Bingel–Hirsch Reaction on Sc₂@C₆₆: A Highly Regioselective Bond Neighboring to Unsaturated Linear Triquinanes

The dispersion-corrected density functional theory (M06-2X) was adopted to investigate the kinetically driven Bingel–Hirsch and thermodynamically controlled Prato reactions on Sc₂@<i>C</i>_2<i>v</i>(4059)-C₆₆ which possesses the unconventional unsaturated linear triquinanes (ULTs), respectively. The mechanism differences of these two reactions on Sc₂@C₆₆ could lead to their different functionalization performances. The investigations on Bingel–Hirsch addition suggest that this process prefers to occur on the C–C bond (9–8) next to other than those (such as 9–10) on the ULT moieties, resulting in a highly regioselective product. The most favorable addition site (atom C₉) for the bromomalonate anion is the only one that connects two equivalent [5,5] C–C bonds (10–11 and 31–30) among all possible atoms. In addition, solvent effect for this reaction was evaluated, and the results suggest that <i>ortho</i>-dichlorobenzene (ODCB) is more feasible than toluene for Sc₂@C₆₆. However, the Prato reaction for this system turned out to show poor regioselectivity to the best reactive bond 10–11