A family of robust Dirac cone materials: two-dimensional hexagonal M3X2 (M = Zn/Cd/Hg, X = Si/Ge).

The fascinating Dirac cone, which has produced some excellent properties in graphene, such as ballistic charge transport, ultra-high carrier mobility and the quantum Hall effect, has motivated researchers to design and study more two dimensional (2D) Dirac materials. In this work, we have designed a family of 2D Dirac cone materials M3X2 (M = Zn/Cd/Hg, X = Si/Ge) and studied their superior properties by first principles calculation. The calculated cohesive energy, phonon dispersion and ab initio molecular dynamics confirmed the energetic, dynamic and thermodynamic stability of Zn3Ge2, Cd3Ge2, Hg3Si2, and Cd3Si2 monolayers. It was found that the intrinsic Dirac cones exist in the electronic structure of the Zn3Ge2, Cd3Ge2, Hg3Si2 and Cd3Si2 monolayers. Their Fermi velocities are from 3.26 × 105 m s-1 to 4.32 × 105 m s-1 (8.2 × 105 m s-1 for graphene). It is noteworthy that the Dirac cone in the M3X2 structure is robust. It is independent of external strain (from -7% to +19%) and can also be preserved as one-dimensional zigzag nanoribbons and multilayers (from two to three-layers). Our work shows that the novel M3X2 Dirac cone materials are an important candidate for high-speed nanoelectronic devices.

Two-dimensional semiconductor materials with high stability and electron mobility in group-11 chalcogenide compounds: MNX (M = Cu, Ag, Au; N = Cu, Ag, Au; X = S, Se, Te; M ≠ N).

It is still an urgent task to find new two-dimensional (2D) semiconductor materials with a suitable band gap, high stability and high mobility for the applications of next generation electronic devices. Based on first-principles calculations, we report a new class of 2D group-11-chalcogenide trielement monolayers (MNX, where M = Cu, Ag, Au; N = Cu, Ag, Au; X = S, Se, Te; M ≠ N) with a wide band gap, excellent stability (dynamic stability, thermodynamic stability and environmental stability) and high mobility. At the mixed density functional level, the energy band gap extends from 0.61 eV to 2.65 eV, covering the ultraviolet-A and visible light regions, which is critical for a broadband optical response. For δ-MNX monolayers, the carrier mobility is as high as 104 cm2 V-1 s-1 at room temperature. In particular, the mobility of δ-AgAuS is as high as 6.94 × 104 cm2 V-1 s-1, which is of great research significance for the application of electronic devices in the future. Based on the above advantages, group-11 chalcogenide MNX monomolecular films have broad prospects in the field of nanoelectronics and optoelectronics in the future.

First-Principles Study of Hydrogen Storage of Sc-Modified Semiconductor Covalent Organic Framework-1.

At present, the development of new carbon-based nanoporous materials with semiconductor properties and high hydrogen storage capacity has become a research hotspot in the field of hydrogen storage and hydrogen supply. Here, we pioneered the study of the hydrogen storage capacity of a scandium (Sc) atom-modified semiconductor covalent organic framework-1 (COF-1) layer. It was found that the hydrogen storage capacity of the COF-1 structure was significantly enhanced after the modification of the Sc atom. We found that each Sc atom of the modified COF-1 structure can stably adsorb up to four H2 molecules, and the average adsorption energy of the four hydrogen molecules is -0.284 eV/H2. Six Sc atoms are stably adsorbed most bilaterally on the cell of the COF-1 unit, which can adsorb 24 H2 molecules in total. In addition, we have further studied the adsorption and desorption behaviors of H2 molecules on the 6Sc-COF-1 surface at 300 and 400 K, respectively. It can be found that each Sc atom of the COF-1 unit cell can stably adsorb three H2 molecules with a hydrogen storage performance of 5.23 wt % at 300 K, which is higher than those of lithium-modified phosphorene (4.4 wt %) and lithium-substituted BHNH sheets (3.16 wt %). At 400 K, all of the adsorbed H2 molecules are released. This confirms the excellent reversibility of 6Sc-COF-1 in hydrogen storage performance. This research has great significance in the application of fuel cells, surpassing traditional hydrogen storage materials.

Identifying Priorities for Harmonizing Guidelines for the Long-Term Surveillance of Childhood Cancer Survivors in the Chinese Children Cancer Group (CCCG).

PURPOSE: Survivors of childhood cancer often experience treatment-related chronic health conditions. Given its vast population, China shares a large proportion of the global childhood cancer burden. Yet, screening and treatment of late effects in survivors of childhood cancer remain underaddressed in most regions of China. This study aimed to identify high-priority late effects for harmonizing screening guidelines within the Chinese Children's Cancer Group (CCCG), as well as barriers and enablers of the implementation of surveillance recommendations in local practice. METHODS: To establish clinical consensus, 12 expert panelists who represent major institutions within the CCCG completed a Delphi survey and participated in a focus group discussion. The survey solicited ratings of the prevalence, severity, and priority for screening of 45 late effects. Major themes identified from the focus group were analyzed using thematic analysis. RESULTS: The Delphi survey identified eight high-priority late effects for harmonization within CCCG: osteonecrosis, osteoporosis, left ventricular dysfunction, secondary brain tumors, treatment-related myeloid leukemia, gonadal dysfunction, growth hormone deficiency, and neurocognitive deficits. The common barriers to implementing survivorship programs include lack of support and resources for clinicians to provide follow-up care. Patients were also concerned about privacy issues and lacked awareness of late effects. Many institutions also lacked rehabilitation expertise and referral pathways. CONCLUSION: By identifying obstacles related to the professional setting, patient behavior, and organization of care, our study identified resources and a framework for establishing collaborative strategies to facilitate follow-up care of childhood cancer survivors in China.

Stress and Perception of Procedural Pain Management in Chinese Parents of Children With Cancer.

OBJECTIVES: Children with cancer are exposed to repeated painful and invasive procedures. This study examines Chinese parents' stress and perception toward their children's procedural pain control. METHODS: We recruited 265 parents of children (aged <18 years) diagnosed with hematological cancer (74.7%) and solid tumors (25.3%) from two major public hospitals. Parents used a scale (0-10) to rate perceived pain experienced by their child when undergoing lumbar puncture (LP), bone marrow aspirate, or/and biopsy. They reported their stress level and attitudes toward analgesics using the adapted Pain Flexibility Scale for Parents and Parental Medication Attitude Questionnaire. General linear modeling was used to identify factors associated with perception outcomes. RESULTS: Parents (72.8% mothers, age 36.5 [6.8] years) expressed that they were worried (31.7%) and had difficulty with concentration (57.7%) when the child was in pain. Among parents whose children had undergone LP (n = 207), 39.1% perceived that their child still experienced severe pain (pain score >7) even with existing pain control measures. Parents reported concerns over side effects of analgesics (69.4%) and addiction (35.1%). Half of the parents (47.2%) perceived that analgesics should only be reserved for severe pain. Parents who were older (estimate = 2.07, SE = 0.87; P = 0.0054) and had lower education attainment (estimate = -3.38, SE = 1.09; P = 0.0021) had a more negative attitude toward analgesics use. Higher parental distress was associated with avoidance of analgesics use (rs = 0.17, P = 0.0052). CONCLUSION: Our findings suggested that subgroups of Chinese parents demonstrated distress with their child's pain and harbored misconceptions over analgesics use. Future work includes devising targeted psychoeducation interventions for these parents.

[Substructure Characteristics of Combined Acid-Base Modified Sepiolite and Its Adsorption for Cd(â ¡)].

To enhance the adsorption capacity of sepiolite (Sep) on Cd2+ in solution, an acid-base Sep (ABsep) was obtained using the method of combined acid-base modification. The structural properties of Sep and ABsep were analyzed by adsorption-desorption isotherms of N2, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). Static adsorption experiments were carried out to evaluate the effects of time, mass ratio of ABsep/Cd2+, temperature, adsorbent dose, pH, and co-existing ions on the adsorption of Cd2+ by ABsep. The results showed that the pore structure of the ABsep was more developed than that of Sep. In comparison to Sep, the specific surface area, average pore diameter, and pore volume of ABsep increased by 66.1%, 15.7%, and 34.8%, respectively, and the exchangeable ion contents also increased. The main components of the ABsep were SiO2 and Mg(OH)2. The adsorption process of Cd2+ by Sep and ABsep could be well fitted with a pseudo-second-order kinetic equation and Langmuir isotherm, and both were spontaneous endothermic reactions, which were mainly chemical adsorption along with physical adsorption. The best mass ratio of ABsep:Cd2+ was 3:1, and the maximum saturated adsorption capacity fitted by the Sips model of the ABsep on Cd2+ at 298 K was 142.43 mg·g-1, which was 3.55 times that of Sep. As the adsorbent dose increased, the adsorption amounts of Cd2+ first increased and then decreased, with the optimum dose being 0.3 g·L-1. The amount of Cd2+ adsorption by the ABsep increased with the initial pH of the solution, whereby the best pH was 7. We also found that the presence of K+, Na+, Mg2+, and Ca2+ at different concentrations could inhibit the adsorption of Cd2+, whereby the inhibition of Mg2+ was the highest.

[Effect of Different Passivating Agents on the Stabilization of Heavy Metals in Chicken Manure Compost and Its Maturity Evaluating Indexes].

We explore the effects of different passivating agents on livestock manure treatment by using chicken manure and straw as raw materials and thermophilic rapid fermentation. We investigate the effects of sepiolite (SE), calcium magnesium phosphate fertilizer (NP), biochar (BI), compounds of sepiolite plus calcium magnesium phosphate fertilizer (S+N), sepiolite plus biochar (S+B), calcium magnesium phosphate fertilizer plus biochar (N+B), and sepiolite plus calcium magnesium phosphate fertilizer and biochar (SNB) on the physical and chemical characteristics, heavy metal fraction and distribution, and organic matter content in chicken manure compost. The results showed that the addition of different passivating agents significantly increased the pH in chicken manure organic fertilizer (P<0.05). The seed germination rate was increased after applying of passivation agents, being>80%, and the germination inhibition rate decreased accordingly, whereas the values of electric conductivity (EC) and organic carbon were inhibited. The total nitrogen content and carbon/nitrogen ratio (C/N) were lower than of those before composting, and all of the indicators reached the standard of organic fertilizer maturity. However, differences among the groups after composting were that the pH increase in the compounding treatment was comparatively higher, and that the EC decreased significantly under the treatment of the single sepiolite and calcium magnesium phosphate, whereas the total nitrogen content and C/N ratio of organic carbon were not significantly different in each group. Although the total amount of heavy metals in our organic chicken manure fertilizer increased due to a concentration effect, the proportion of exchangeable heavy metals in the fertilizer decreased, and while the ratio of the residual heavy metals increased. The passivation effect on heavy metals under combined treatments of different materials was better than that of a single agent, and the SNB treatment had the best effect on the passivation of Ni, Zn, As, and Pb. After composting treatment, the concentrations of humic substances (HS) and humic acid (HA) increased significantly (P<0.05), and the highest concentrations increased by 19.8% and 78.9%, respectively. The amount of fulvic acid (FA) decreased by 4.47%-20.11% compared with the initial conditions. Infrared spectroscopy analysis showed that the small molecular substances of polysaccharides increased after composting. In summary, the addition of a passivation agent can promote the heavy metal passivation in chicken manure organic fertilizers to potentially render the compost as harmless.

On-surface synthesis of one-type pore single-crystal porous covalent organic frameworks.

Employing a 1,3,5-tris(4-bromophenyl)benzene precursor as a building block, we successfully fabricate large-scale, non-multihole and single-layer pCOFs on the Ag(111) surface in a controllable manner via the on-surface reaction. We reveal that two main factors, the heating rate and growth temperature, have a strong impact on the size and quality of the pCOFs by STM. Furthermore, the band gap of the pCOFs has been further measured to be approximately 3.01 eV.

Vapour Phase Dehydration of Glycerol to Acrolein Over Wells-Dawson Type H6P2W18O62 Supported on Mesoporous Silica Catalysts Prepared by Supercritical Impregnation.

The H6P2W18O62/MCM-41-SUP was first synthesized using supercritical impregnation as highly efficient catalyst during glycerol conversion reaction. For comparison, the H6P2W18O62/MCM-41 prepared by conventional wet impregnation was also studied. The catalysts were studied using XRD, BET, FTIR, SEM, TEM, pyridine-FTIR, NH3-TPD, TG, ICP and elemental analysis. The characterization results showed that the preparation condition of supercritical carbon dioxide contributed to improve the dispersion of H6P2W18O62 on MCM-41, strengthen the interaction between H6P2W18O62 and MCM-41, increase the thermostability of H6P2W18O62 and enhance the amount of medium and Brønsted acid sites on the catalyst. Therefore, the formation of coke was retarded, and the lifetime of catalyst was prolonged. After 15 h reaction, the glycerol conversion rapidly reduced from 92% to 64% on H6P2W18O62/MCM-41-IMG (15.4 wt% coke), while the glycerol conversion slightly decreased from 94% to 82% on H6P2W18O62/MCM-41-SUP (9.8 wt% coke).