Materials for supercapacitors: When Li-ion battery power is not enough

Supercapacitors, also known as electrochemical capacitors, have witnessed a fast evolution in the recent years, but challenges remain. This review covers the fundamentals and state-of-the-art developments of supercapacitors. Conventional and novel electrode materials, including high surface area porous carbons for electrical double layer capacitors (EDLCs) and transition metal oxides, carbides, nitrides and their various nanocomposites for pseudocapacitors – are described. Latest characterization techniques help to better understand the charge storage mechanisms in such supercapacitors and recognize their current limitations, while recently proposed synthesis approaches enable various breakthroughs in this field.     

Preparation of an exponentially rising optical pulse for efficient excitation of single atoms in free space

We report on a simple method to prepare optical pulses with exponentially rising envelope on the time scale of a few ns. The scheme is based on the exponential transfer function of a fast transistor, which generates an exponentially rising envelope that is transferred first on a radio frequency carrier, and then on a coherent cw laser beam with an electro-optical phase modulator. The temporally shaped sideband is then extracted with an optical resonator and can be used to efficiently excite a single (87)Rb atom.     

One‐Step Formulation of Protein Microparticles with Tailored Properties: Hard Templating at Soft Conditions

Formulation of therapeutic proteins into particulate forms is a main strategy for site‐specific and prolonged protein delivery as well as for protection against degradation. Precise control over protein particle size, dispersity, purity, as well as mild preparation conditions and minimal processing steps are highly desirable. It is, however, hard to fit all these criteria with conventional preparation techniques. Here a one‐step hard‐templating synthesis of microparticles composed of functional, non‐denatured protein is reported. The method is based on filling porous CaCO₃ microtemplates with the protein near to its isoelectric point (pI) followed by pH‐ or EDTA‐mediated dissolution of the tempplates. In principle, a wide variety of proteins can be converted into microparticles using this approach. The main requirement is an overlap of the protein insolubility and a template solubility for a certain parameter (here pH or EDTA). Here the formulation of insulin particles is studied in detail and it is shown that particles consisting of high molecular weight protein (catalase) can also be prepared. In this context, the synthesis of CaCO₃ templates with controlled size, the mechanism of the protein microparticle formation and mechanical properties of the microparticles are discussed. For the first time, the fabrication of mesoporous monodispersed CaCO₃ microtemplates with identical porocity but tuned diameter from 3 to 20 μm is demonstrated. The protein particle diameter can be adjusted by choosing the appropriate template size that is critical for successful pulmonary delivery of insulin. As a first step towards insulin delivery, the in vitro release of insulin at physiological conditions is studied.     

Use of photodegradable inhibitors in UV-curable compositions to form polymeric 2D-structures by visible light

The process of two-wave photopolymerization of a UV-curable composition with an optically degrading inhibitor is considered. By numerical simulation, it is shown that in the composition layer uniformly exposed to UV-radiation, such systems allow getting segments with different conversion under the action of inhomogeneous visible light. Based on the data on the photopolymerization kinetics of the compositions from triethylene glycol dimethacrylate (TEGDMA) and bisphenol-A glycidyl dimethacrylate (bis-GMA) with the UV-initiator 2,2-dimethoxy-2-phenylacetophenone (DMPA), it was shown that 3,5-di-tert-butyl-o-benzoquinone (35Q) with N,N-dimethylaniline (DMA, “Aldrich”, 99%) can serve as an inhibitor that degrades under action of visible radiation. Combining inhomogeneous visible light generated with a conventional DLP-projector and uniform UV-radiation of LED (365 nm) the two-wave lithographic process was implemented to create polymeric 2D-structures in 20 μm layer of the compositions from TEGDMA (70)/bis-GMA (30)/DMPA (0.05 wt%)/35Q (0.5 wt%)/DMA (1 wt%).     

Stochastic geometry of network of randomly distributed moving vehicles on a highway

Vehicular ad hoc networks (VANETs) have become an extensively studied topic in contemporary research. One of the fundamental problems that has arisen in such research is understanding the network statistical properties, such as the cluster number distribution and the cluster size distribution. In this paper, we analyze these characteristics in the case in which vehicles are located on a straight road. Assuming the Rayleigh fading model and a probabilistic model of intervehicle distance, we derive probabilistic distributions of the aforementioned connectivity characteristics, as well as distributions of the biggest cluster and the number of disconnected vehicles. All of the results are confirmed by simulations carried out for the realistic values of parameters.     

A cubic ordered, mesoporous carbide-derived carbon for gas and energy storage applications

A hierarchical and highly porous carbide-derived carbon (CDC) was obtained by nanocasting of pre-ceramic precursors into cubic ordered silica (KIT-6) and subsequent chlorination. Resulting CDC replica materials show high methane and n-butane uptake and excellent performance as electrode materials in supercapacitors.     

Viral quantitative capillary electrophoresis for counting intact viruses

The quantification of a virus plays an important role in vaccine development, clinical diagnostics, and environmental contamination assays. In all these cases, it is essential to calculate the concentration or number of intact virus particles (ivp) and estimate the degree of degradation and contamination of virus samples. In this work, we propose a cost-efficient, robust method for the quantification and characterization of intact viruses based on capillary zone electrophoresis. This separation method is demonstrated on vaccinia virus (VV) with oncolytic properties. After virus sample preparation, the solution contains intact VV as well as broken viruses and residual DNA from the host cell used for preparation. Regulatory requirements limit the amount of the host cell DNA that can be present in vaccines or human therapeutics. We apply capillary electrophoresis to separate intact virus particles and the residual DNA and to measure the level of virus contamination with DNA impurities. Intercalating YOYO-1 dye is used to detect the encapsulated and free DNA by laser-induced fluorescence. After soft lysis of VV with proteinase K, all encapsulated DNA is dissolved to the free DNA. The change in peak areas and a DNA calibration curve help determine the initial concentration of intact viruses. This viral quantitative capillary electrophoresis (Viral qCE) is able to quantify the oncolytic vaccinia virus in the range of 10(6) to 10(12) ivp/mL.