Evaluation of a New Method to Estimate the Micropore Volume and External Surface Area of Single-walled Carbon Nanotubes

Since the discovery of carbon nanotubes in 1991, significant progress has been made to understand their electrical, mechanical, magnetic and optical properties. However, as the ideal adsorbent for adsorption of gases and vapors, nanotubes, especially the single-walled carbon nanotubes (SWNTs), and their adsorption properties remain not been investigated enough. The unique microporous structure of SWNTs gives them remarkable adsorption properties, i.e. surface area and porosity. Several methods exist to determine the surface area and pore volume of adsorbents: t-plot method, Dubinin-Radushkevich (DR) method, and Dubinin-Astakhov (DA) method. The results are usually specific to a certain method and to the segment of the adsorption isotherm which is fitted to the method used. Therefore, the main objective of this study is to find the most appropriate and suitable method to characterize micropore volume and external surface area of SWNTs. The surface area and porosity results are often used to evaluate the effectiveness of an adsorbent for removal of odors and trace concentrations of organic vapors from air and process streams. The objective is accomplished by evaluating the results of t-plot method, DR method, DA method and a method that was recently developed. Some of the commonly used methods were developed as far back as 1940s. Additionally, the methods were developed for various adsorbents such as carbon black, zeolites and activated carbon. However, nanotubes are fairly recent adsorbent materials. All of these can render the characterization results open to the interpretation by a specific user. In this study standard N2 adsorption was carried out at 77 K for four commerciallyavailable SWNT sample. The impurities of SWNTs were able to be incorporated into the adsorption isotherm, the results of which could be confirmed by thermogravimetric analysis (TGA) and X-ray photo spectroscopy (XPS) experiments. To make the new developed method applicable to impure SWNT samples, new definition of statistical thickness has been proposed in this study. The consistent results showed the advantages of the modified new method, which is applicable and specific to SWNT samples. Multiple adsorbates should be used in the future analysis, such as water vapor, hexane, and other organic vapors

Dimensional Analysis and the Time Required to Urinate

According to the recently discovered 'Law of Urination', mammals, ranging in size from mice to elephants, take, on the average, 21s to urinate. We attempt to gain insights into the physical processes responsible for this uniformity using simple dimensional analysis. We assume that the biological apparatus for urination in mammals simply scales with linear size, and consider the scenarios where the driving force is gravity or elasticity, and where the response is dominated by inertia or viscosity. We ask how the time required for urination depends on the length scale, and find that for the time to be independent of body size, the dominant driving force must be elasticity, and the dominant response viscosity. Our note demonstrates that dimensional analysis can indeed readily give insights into complex physical and biological processes

Exploring Metaverse Addiction: Lenses of Technology Affordance and Compensatory Actualization

As technology further evolves, the metaverse is becoming an increasingly plausible reality. In this process, it is crucial to consider potential risks that come with its development. This study focuses on the potential risk of metaverse addiction and considers the influencing factors from the perspective of technology affordance and virtual reality compensatory effect. Mainly, we identify metaverse affordances based on key characteristics (i.e., accessibility, immersion, spatiotemporality, sustainability, interoperability, and scalability). It also highlights two kinds of affordance actualization factors (i.e., escapism and digital perfectionism) that arise from virtual reality compensatory theory. The research model suggests that metaverse affordance is actualized through compensation, ultimately forming reliance behavior like an addiction. This conceptual research potentially contributes to further investigation of the dark side of the metaverse and provides insights into research considering the compensatory effects to mitigate potential risks and ensure the healthy development of the metaverse

Theoretical investigation of the dynamic electronic response of a quantum dot driven by time-dependent voltage

We present a comprehensive theoretical investigation on the dynamic electronic response of a noninteracting quantum dot system to various forms of time-dependent voltage applied to the single contact lead. Numerical simulations are carried out by implementing a recently developed hierarchical equations of motion formalism [J. Chem. Phys. 128, 234703 (2008)], which is formally exact for a fermionic system interacting with grand canonical fermionic reservoirs, in the presence of arbitrary time-dependent applied chemical potentials. The dynamical characteristics of the transient transport current evaluated in both linear and nonlinear response regimes are analyzed, and the equivalent classic circuit corresponding to the coupled dot-lead system is also discussed

Exact dynamics of dissipative electronic systems and quantum transport: Hierarchical equations of motion approach

A quantum dissipation theory is formulated in terms of hierarchically coupled equations of motion for an arbitrary electronic system coupled with grand canonical Fermion bath ensembles. The theoretical construction starts with the second--quantization influence functional in path integral formalism, in which the Fermion creation and annihilation operators are represented by Grassmann variables. Time--derivatives on influence functionals are then performed in a hierarchical manner, on the basis of calculus--on--path--integral algorithm. Both the multiple--frequency--dispersion and the non-Markovian reservoir parametrization schemes are considered for the desired hierarchy construction. The resulting formalism is in principle exact, applicable to interacting systems, with arbitrary time-dependent external fields. It renders an exact tool to evaluate various transient and stationary quantum transport properties of many-electron systems. At the second--tier truncation level the present theory recovers the real--time diagrammatic formalism developed by Sch\"{o}n and coworkers. For a single-particle system, the hierarchical formalism terminates at the second tier exactly, and the Landuer--B\"{u}ttiker's transport current expression is readily recovered.Comment: The new versio