Exceptionally Stiff Two-Dimensional Molecular Crystal by Substrate-Confinement

We demonstrated an approach to effectively apply in-plane pressures to molecular layers by utilizing the substrate confinement effect. The compressed crystal structure and mechanical behaviors of carbon monoxide (CO) monolayer subjected to the confinement of Cu(100) substrate were jointly investigated by low temperature scanning tunneling microscopy experiments and first-principles density functional theory calculations. By increasing molecular coverage, an exceptionally large Young’s modulus of 33 GPa was derived for the constrained CO monolayer film. This extreme in-plane pressure leads to site-specific tilting geometries, polymeric-like electronic states, and vibrational behaviors of CO molecules in the compressed phases. These results provide an extended understanding of the physical and chemical properties of intermolecular interactions in this fundamental system

Unveiling Structurally Engineered Carrier Dynamics in Hybrid Quasi-Two-Dimensional Perovskite Thin Films toward Controllable Emission

Quasi-two-dimensional Ruddlesden–Popper perovskites driving carrier self-separation have rapidly advanced the development of high-performance optoelectronic devices. However, insightful understanding of carrier dynamics in the perovskites is still inadequate. The distribution of multiple perovskite phases, crucial for carrier separation, is controversial. Here we report a systematic study on carrier dynamics of spin-coated (C₆H₅CH₂CH₂NH₃)₂(CH₃NH₃)_<i>n</i>−1Pb_<i>n</i>I_3<i>n</i>+1 (<i>n</i> = 3 and 5) perovskite thin films. Efficient electrons transfer from small-<i>n</i> to large-<i>n</i> perovskite phases, and holes transfer reversely with time scales from ∼0.3 to 30.0 ps. The multiple perovskite phases are arranged perpendicularly to substrate from small to large <i>n</i> and also coexist randomly in the same horizontal planes. Further, the carrier separation dynamics is tailored by engineering the crystalline structure of the perovskite film, which leads to controllable emission properties. These results have important significance for the design of optoelectronic devices from solar cells, light-emitting diodes, lasers, and so forth

Thermally Induced Transformation of Nonhexagonal Carbon Rings in Graphene-like Nanoribbons

Exploring the structural transformation of nonhexagonal rings is of fundamental importance for understanding the thermal stability of nonhexagonal rings and revealing the structure–property relationships. Here, we report on the thermally induced transformation from the fused tetragon-hexagon (4–6) carbon rings to a pair of pentagon (5–5) rings in the graphene-like nanoribbons periodically embedded with tetragon and octagon (4–8–4) carbon rings. A distinct contrast among tetragon, pentagon, hexagon, and octagon carbon rings is provided by noncontact atomic force microscopy with atomic resolution. The thermally activated bond rotation with the dissociation of the shared carbon dimer between the 4–6 carbon rings is the key step for the 4–6 to 5–5 transformation. The energy barrier of the bond rotation, which results in the formation of an irregular octagon ring in the transition state, is calculated to be 1.13 eV. The 5–5 defects markedly change the electronic local density of states of the graphene-like nanoribbon, as observed by scanning tunneling microscopy. Our density functional theory calculations indicate that the introduction of periodically embedded 5–5 rings will significantly narrow the electronic band gap of the graphene-like nanoribbons

Relationship between Anxiety and Burnout among Chinese Physicians: A Moderated Mediation Model

<div><p>Objective</p><p>The main goal of this research was to investigate the complex relationships among coping styles, personality, burnout, and anxiety using a moderated mediation analysis.</p><p>Methods</p><p>A random cluster sampling procedure was used to select a total of 1274 physicians from two tertiary grade A hospitals in Heilongjiang Province, which is located in northeast China. The Zung Self-Rating Anxiety Scale (SAS), Chinese Maslach Burnout Inventory (CMBI), Chinese version of the EPQ-revised Short Scale, and the Trait Coping Style Questionnaire (TCSQ) were used to gather data. Moderated mediation analysis was used in this study; it was executed using the PROCESS macro so that the mediators and moderator could function together in the same model.</p><p>Results</p><p>The prevalence of anxiety symptoms among the physicians was 31%, and there were no differences between the sexes. The results showed that positive and negative coping styles partially mediated the association between burnout and anxiety symptoms in physicians. The mediated effect of positive coping styles was moderated by Eysenck’s Psychoticism traits.</p><p>Conclusions</p><p>Personality traits moderate the strength of the relationships between burnout and anxiety mediated by positive coping styles; however, personality traits do not moderate the strength of the relationships between burnout and anxiety mediated by negative coping styles.</p></div

Participants’ characteristics and the distribution of anxiety symptoms.

<p>Participants’ characteristics and the distribution of anxiety symptoms.</p

Charge-Pattern Indicated Relaxation Dynamics and Glass Transition of Polymer Thin Films Studied by Atomic Force Microscopy

Polymers are widely used as dielectrics in microelectronics. As the thickness of polymer films decreases to the submicrometer or nanometer scale, abnormal relaxation deviations from the bulk matrix are expected. Evaluation of the relaxation dynamics in an efficient and quantitative manner is highly desired. Utilizing this patterned charge as an indicator, we demonstrate here that the polymer relaxation dynamics and glass transition temperature (<i>T</i>_g) of thin polymer films can be investigated by monitoring the charge decay behaviors. This approach of charge patterning combined with atomic force microscopy is more facile to evaluate polymer relaxation behavior with direct contrast between charged and electrically neutral domains versus conventional polymer <i>T</i>_g and relaxation dynamic measurements. This study also illuminates the coexisting processes of polymer relaxation and trapped charge decay in thin polymer film. This sheds light on the microscopic mechanism of charge storage and relaxation properties in the polymer

Means, standard deviations (SD) and correlations of continuous variables.

<p>**. Correlation is significant at the 0.01 level (2-tailed).</p><p>Means, standard deviations (SD) and correlations of continuous variables.</p

Conditional indirect effect at specific levels of the moderator when treating positive coping as a mediator (N = 1129).

<p>Conditional indirect effect at specific levels of the moderator when treating positive coping as a mediator (N = 1129).</p

The final moderated mediation model.

<p>The link associating the burnout and positive coping with anxiety is moderated by personality traits.</p