Carbon‐Based Metal‐Free Catalysts for Energy Storage and Environmental Remediation

Owing to their high earth‐abundance, eco‐friendliness, high electrical conductivity, large surface area, structure tunability at the atomic/morphological levels, and excellent stability in harsh conditions, carbon‐based metal‐free materials have become promising advanced electrode materials for high‐performance pseudocapacitors and metal–air batteries. Furthermore, carbon‐based nanomaterials with well‐defined structures can function as green catalysts because of their efficiency in advanced oxidation processes to remove organics in air or from water, which reduces the cost for air/water purification and avoids cross‐contamination by eliminating the release of heavy metals/metal ions. Here, the research and development of carbon‐based catalysts in supercapacitors and batteries for clean energy storage as well as in air/water treatments for environmental remediation are reviewed. The related mechanistic understanding and design principles of carbon‐based metal‐free catalysts are illustrated, along with the challenges and perspectives in this emerging field.     

Indirect cytotoxicity evaluation of pseudowollastonite

This study aimed to evaluate the cytotoxicity of substances leached by pseudowollastonite (CaSiO₃). It has been previously shown that calcium (Ca²⁺) and silicate (SiO₃ ^–) ions are released from pseudowollastonite into biological solutions. Both of these ions are known to influence the biological metabolism of osteoblastic cells essential in the mineralization process and bone-bonding mechanism. The indirect toxicity evaluation was performed by extraction method, according to International Standard Organization (ISO). Pseudowollastonite pellets obtained by solid-state reaction were incubated, in culture medium, during 24, 48, 72 or 168 h at different concentrations (5, 10, 15, 50, 100, 200 mg/ml). The cytotoxicity of each extract in presence of human osteoblastic cell line (SaOS-2) was quantitatively assessed by measuring the viability (succinate dehydrogenase activity, MTT), the membrane integrity (the uptake of the neutral red by viable cells, NR) as well as the cell necrosis by measuring the lactate dehydrogenase (LDH) released in the culture medium. No significant alteration of membrane integrity or cell suffering was detectable. However, increased cell metabolism was observed for cells exposed to pseudowollastonite extract with longest extraction time (168 h). In conclusion, mineral elements leached by pseudowollastonite do not significantly affect the metabolism of osteoblastic cells.     

The Complexity of Hybrid Logics over Equivalence Relations

This paper examines and classifies the computational complexity of model checking and satisfiability for hybrid logics over frames with equivalence relations. The considered languages contain all possible combinations of the downarrow binder, the existential binder, the satisfaction operator, and the global modality, ranging from the minimal hybrid language to very expressive languages. For model checking, we separate polynomial-time solvable from PSPACE-complete cases, and for satisfiability, we exhibit cases complete for NP, PSpace, NExpTime, and even N2ExpTime. Our analysis includes the versions of all these languages without atomic propositions, and also complete frames.     

Superconductivity,structural disorder,and phase transitions in ion-irradiated Nb3Al films

Thin films of single-phase A15 Nb₃Al were irradiated with protons and nitrogen ions. X-ray intensity analysis revealed a decrease of the Bragg-Williams long-range order parameterS and an increase of the average displacement amplitude of the atomsU in the fluence region where a decrease of the superconducting transition temperatureT _c was observed. The functional dependence ofT _c onS andU was found to depend on the ion species used for irradiation. After irradiation with 10¹⁶ N²⁺ / cm² the A15 phase transformed into an A2 phase. Furnace annealing caused a retransformation into the A15 phase with improved superconducting properties.     

The development and validation of the Self-directed Learning Scales (SLS)

This article describes the development and validation of the Self-directed Learning Scales (SLS) using data from 14,846 secondary students. Self-directed learning refers to a process whereby the learner consciously and actively directs his/her actions in the learning process. The SLS comprised a battery of subscales measuring students' goal setting, planning, academic motivation, academic self-efficacy, inquiry and information processing, strategic help-seeking, management of learning resources, and self-monitoring. Rasch analysis following factor analyses provided evidence in support of the validity of SLS for use with secondary students. Two original subscales were merged with other subscales on the basis of the analyses, resulting in 19 subscales with strong psychometric properties in the Self-directed Learning Scales.     

Trusted Computing in Context

The trusted computing technology embodied in the Trusted Platform Module secure-coprocessor from the Trusted Computing Group is a hardware-based root of trust that makes it possible for the system designer--not the computer owner--to regulate which programs can run on a given computer. If system designers are evil, then they can use trusted computing to prevent a competitors' programs from being installed, thus creating or preserving a monopoly. When computer owners are incompetent, though, benevolent system designers can use trusted computing to prevent malware from being installed and run.