[en] The tribological behaviors of the (W_0_._6_7Al_0_._3_3)C_0_._6_7–Co/fluoride (CaF_2, BaF_2, CaF_2/BaF_2) composites against SiC ball from room temperature to 600 °C were investigated. A marked increase in the friction coefficient resulting from fluoride oxidation was observed as the temperature increased. The composites containing BaF_2 or (Ca, Ba)F_2 displayed better integrated wear resistance over a wide temperature range compared with (W_0_._6_7Al_0_._3_3)C_0_._6_7–Co/CaF_2. The high temperature tribological characteristics of the three composites were distinct, which originated from the composition difference on the worn surfaces. First, the SiO_2/SiC film formed on the worn surfaces of the composites with BaF_2 or (Ca, Ba)F_2 was favorable for their wear resistance. Second, the oxidation of WC matrix was an important factor influencing the wear resistance of the composites. When mixture oxides of WO_2 and WO_3 appeared on the surface, wear is severe. In addition, single WO_3 formed on the worn surfaces, appeared more adhesive to the underlying substrate and decreased the wear rate. - Highlights: • The composites containing BaF_2 or (Ca, Ba)F_2 exhibit better wear resistance. • The tribological behaviors are strongly correlated to surface composition. • The stoichiometry difference in the tungsten oxides leads to distinct wear rate. • The friction coefficient of the composites increases with the testing temperature

[en] Ovarian cancers, as common malignant tumors in female reproductive system, are difficult to be detected in early phase and are diagnosed in mid-late stage in most cases, often accompanied with peritoneal metastasis, which results in a difficulty of complete resection and a high recurrence rate. These conditions are closely linked to the unclearness of a series of mechanisms that trigger tumor growth, initiate tumor angiogenesis, promote tumor migration and invasion and facilitate immune evasion in the tumor microenvironment composed by tumor cells, tumor matrix, inflammatory cells and stromal cells. Studying and estimating ovarian tumor microenvironment in a dynamic, multivariant and noninvasive way with structural, functional and molecular imaging methods together is of great importance to monitor biological behavior and therapeutic effect of ovarian tumors and to judge tumor prognosis. (authors)

[en] Highlights: • The interfacial microscopic mechanisms and implications for anti-fouling were studied. • Simulation and experimental results were got to verify the rationality of analysis. • Performance of anti-fouling relies on the properties of interfacial layer. Although understanding the correlation between the microscopic mechanism of fluid flow and the fouling process at solid/liquid interfaces is of great theoretical and practical importance, this topic remains poorly studied. We investigated the microscopic mechanisms of flow at solid/liquid interfaces using molecular dynamics simulations and experiments with specially designed surfaces to understand the implications for anti-fouling processes. The interfacial layers absorbed close to the solid surfaces were closely related to surface fouling. Based on the analysis of the microscopic simulations and macroscopic experiments, weaker interfacial adsorption (c: 2–0.2) or lower surface roughness (L: 7.85–1.96 Å) or higher flow velocity (v: 10–80 m/s) leads to lower density and shear viscosity in the interfacial layer. Furthermore, a larger velocity gradient generates a higher shear stress. These changes in properties greatly reduce aggregation in the interfacial layer along with adhesion of planktonic microorganisms and suspended solids to the solid surface, which are conducive to anti-fouling.

[en] Highlights: • A broadband photodetector based on Si/ZnO/CdO heterojunctions is fabricated. • Thepotential barrierat ZnO/CdO interface reduces the possibility of recombination. • The piezo-phototronic effect is used to enhance the performance of photodetectors. The broadband and self-powered photodetectors have attracted significant attention due to the versatility and without extra energy. In this work, we fabricate a self-powered and broadband photodetector based on Si/ZnO/CdO three-component heterojunctions. The photodetector has a fast response time (shorter than 0.45 s) to the ultraviolet and visible illumination at 0 V bias. CdO film is used as the transparent electrode because of the superior electrical characterization and the appropriate band structure of ZnO/CdO, which facilitates electrons transferring from ZnO nanorods to the CdO electrode and reflects holes back into the ZnO, thus reducing recombination at the ZnO/CdO interface and enhancing photocurrent. Moreover the performance of the photodetector is optimized and significantly enhanced by the piezo-phototronic effect of ZnO nanorods. This work may provide a potential approach to enhance the performance of self-powered and broadband photodetectors.

[en] In this work, we report the fabrication of self-powered Si/ZnO heterojunction ultraviolet and visible photodetectors (PDs) with different doping concentrations. The PDs have a fast response time (shorter than 0.13 s) to the ultraviolet and visible illumination at 0 V bias. The photocurrent of Sample A (high doping concentration) is more than 20 times larger than Sample B (low doping concentration) under 365 nm illumination and more than 150 times larger than Sample B under 450 nm illumination. The larger photoresponse is attributed to the stronger built-in electric field of Si/ZnO heterojunction. Furthermore, we demonstrate the impact of the piezo-phototronic effect for the self-powered Si/ZnO heterojunction ultraviolet and visible photodetector. Under a 0.7N compressive strain, the maximal UV and visible photocurrents are enhanced by about 33.7% and 13.9% for sample A (high doping concentration), about 67.3% and 74.5% for sample B (low doping concentration), respectively. The possible working principle is that the positive piezoelectric charges at the Si/ZnO interface lower the local energy band level of ZnO, thus strengthening the built-in electric field and shift the depletion region to the Si side leading to an increase in the photon-absorption volume. This work may provide a potential approach to enhance the performance of the self-powered Si/ZnO heterojunction ultraviolet and visible photodetector. (paper)

[en] A systematic density functional theory study including 17 exchange-correlation functionals was performed on different types of superhalogens with high level coupled-cluster single double including perturbative triple excitations (CCSD(T)) results as the reference. The superhalogens selected here cover the ranges from mononuclear to polynuclear structures and from structures with halogen-atom ligands to those with non-halogen ligands, e.g., [MgX_3]"−, [Mg_2X_5]"−, and [Mg_3X_7]"− (X = F, Cl, CN). It is clearly indicated that three double-hybrid functionals B2T-PLYP, B2GP-PLYP, B2K-PLYP as well as the range-separated hybrid functional ωB97X are capable of providing results which approach the accuracy at the CCSD(T) level. The basis set effect is usually moderate and, in most cases, it is enough to utilize the basis set of triple-ξ quality, e.g., Def2-TZVP. In addition, the results of the HF and MP2 method are also acceptable here, especially for polynuclear superhalogens where CCSD(T) is probably unpractical

[en] Greener protocols, long duration and applications are the necessary conditions of antifouling coating. The stability of anti-bacterial function decides its duration. Core–shell structured nanoparticles with Ag NPs and Ag"+ were successfully in situ fabricated in polyelectrolyte matrix, to avoid antimicrobial nanomaterials leaching out in the form of Ag or Ag"+ from the matrix. The nanocomposite materials prepared were well characterized by XRD, XPS, TEM and UV–visible. Through monitoring the hybrid polymer films soaked in the solution, sparingly soluble AgI as the shell in the hybrid structure nanoparticles showed excellent barrier effect. Using the synergy of Ag NPs and Ag"+ toward the killing of microbes, the duration of antimicrobial activity was prolonged. (paper)

[en] This work presents first-principle investigations into the charge carrier mobility of carbon nanotubes containing monovacancy or related defects. The pristine and defective zigzag (10, 0) tubes were selected to explore the role of defects on the charge carrier mobility. It was found that the electron mobility of one defective structure was unexpectedly increased, while most others were decreased upon the appearance of the defect. To further understand the modification of the carrier mobility induced by monovacancy or related defects, crystal orbital analysis was performed. It was observed that the vacancy defect plays an important role in the case of both increased and decreased mobility. The unusual increased carrier mobility was mainly derived from the weaker acoustic scattering due to the modified wave-function induced by the defect. As for the decreased carrier mobilities, the heavier carrier determined by localized wave-functions, caused by the defects, is the most important factor. (paper)

[en] The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M_2(CN)_5]"−"1 (M =  Ca, Be) clusters. At CCSD(T) level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE). The largest one is 9.70 eV for [Ca_2(CN)_5]"−"1 which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T), outer valence Green’s function (OVGF) method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties

[en] In this paper, a novel strategy for the fabrication of sensitive reagentless amperometric immunosensor was proposed. Firstly, Prussian blue nanoparticles (PBNPs) as redox probe were immobilized on three dimensional structured membrane of the gold colloidal nanoparticles (AuNPs) doped chitosan-multiwall carbon nanotubes (CS-MWNTs) homogeneous composite (CS-MWNTs-AuNPs) by electrostatic interactions between the negatively charged PBNPs and the positively charged amino groups of CS and strong binding interaction between GNPs and nitrile group (-CN) of PBNPs. Subsequently, the gold nanoparticles (GNPs) were electrodeposited on the surface of the composite by electrochemical reduction of gold chloride tetrahydrate (HAuCl₄) to immobilize antibody biomolecules (anti-CEA) and avoid the leakage of PBNPs. The stepwise assembly process was characterized by means of cyclic voltammetry (CV) and electrochemical impendance spectroscopy (EIS). Furthermore, the morphology of the prepared nanomaterials was researched by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Under the optimized conditions, the decrease of CVs current of determination CEA was proportional to concentration ranges from 0.3 to 120 ng/mL with a detection limit of 0.1 ng/mL at a signal-to-noise of 3. Moreover, the proposed immunosensor exhibited good accuracy, high sensitivity and stability.