High Energy Density Supercapacitors: An Overview of Efficient Electrode Materials,Electrolytes, Design,and Fabrication

Supercapacitors (SCs) are potentially trustworthy energy storage devices, therefore getting huge attention from researchers. However, due to limited capacitance and low energy density, there is still scope for improvement. The race to develop novel methods for enhancing their electrochemical characteristics is still going strong, where the goal of improving their energy density to match that of batteries by increasing their specific capacitance and raising their working voltage while maintaining high power capability and cutting the cost of production. In this light, this paper offers a succinct summary of current developments and fresh insights into the construction of SCs with high energy density which might help new researchers in the field of supercapacitor research. From electrolytes, electrodes, and device modification perspectives, novel applicable methodologies were emphasized and explored. When compared to conventional SCs, the special combination of electrode material/composites and electrolytes along with their fabrication design considerably enhances the electrochemical performance and energy density of the SCs. Emphasis is placed on the dynamic and mechanical variables connected to SCs′ energy storage process. To point the way toward a positive future for the design of high-energy SCs, the potential and difficulties are finally highlighted. Further, we explore a few important topics for enhancing the energy densities of supercapacitors, as well as some links between major impacting factors. The review also covers the obstacles and prospects in this fascinating subject. This gives a fundamental understanding of supercapacitors as well as a crucial design principle for the next generation of improved supercapacitors being developed for commercial and consumer use.     

Two sum theorems for topological spaces

Two general criterias for the union of topological spaces of a given type to be also of the same type, are presented.     

Pyrene-neomycin conjugate: dual recognition of a DNA triple helix

We report the synthesis of pyrene-neomycin conjugate and its ability to stabilize DNA/RNA triple helices.     

A 0.5 V tunable complex filter for Bluetooth and Zigbee using OTAs

A 12th-order low voltage tunable differential complex filter for bluetooth and Zigbee applications is proposed in this paper. The filter is based on improved controllable transconductors operating with the ultra-low supply voltage of 0.5 V. Simulation results using a triple-well 0.13 μm CMOS technology verify the filter operation fulfilling all the requirements for the complex filtering stage in bluetooth or Zigbee receivers. The in-band group delay variation is 0.79 μs for bluetooth and 0.46 μs for Zigbee. The image rejection ratio is greater than 71 dB and the achieved in-band spurious free dynamic range is 42 dB.     

Dynamic Electromechanical Hydrogel Matrices for Stem Cell Culture

Hydrogels have numerous biomedical applications including synthetic matrices for cell culture and tissue engineering. Here we report the development of hydrogel based multifunctional matrices that not only provide three‐dimensional structural support to the embedded cells but also can simultaneously provide potentially beneficial dynamic mechanical and electrical cues to the cells. A unique aspect of these matrices is that they undergo reversible, anisotropic bending dynamics in an electric field. The direction and magnitude of this bending can be tuned through the hydrogel crosslink density while maintaining the same electric potential gradient, allowing control over the mechanical strain imparted to the cells in a three‐dimensional environment. The conceptual design of these hydrogels was motivated through theoretical modeling of the osmotic pressure changes occurring at the gel‐solution interfaces in an electric field. These electro‐mechanical matrices support survival, proliferation, and differentiation of stem cells. Thus, these new three‐dimensional in vitro synthetic matrices, which mimic multiple aspects of the native cellular environment, take us one step closer to in vivo systems.     

Influence of Moringa oleifera on pharmacokinetic disposition of rifampicin using HPLC‐PDA method: a pre‐clinical study

The influence of active fraction isolated from pods of an indigenous plant, Moringa oleifera (MoAF) was studied on the pharmacokinetic profile of the orally administered frontline anti‐tuberculosis drug rifampicin (20 mg/kg b.w.) in Swiss albino mice. The antibiotic rifampicin alone and in combination with MoAF (0.1 mg/kg b.w.) was administered orally and heparanized blood samples were collected from the orbital plexus of mice for plasma separation at 0, 1, 2, 3, 4 and 5 h, post treatment. Plasma rifampicin concentration, pharmacokinetic parameters and drug metabolizing enzyme (cytochrome P‐450) activity were determined. The pharmacokinetic data revealed that MoAF‐treated animals had significantly increased rifampicin plasma concentration, C_max, K_el, t_½(a), t_½(el), K_a and AUC as well as inhibited rifampicin‐induced cytochrome P‐450 activity. In conclusion, the result of this study suggested that the bioavailability‐enhancing property of MoAF may help to lower the dosage level and shorten the treatment course of rifampicin. Copyright © 2010 John Wiley & Sons, Ltd.     

Neomycin-neomycin dimer: an all-carbohydrate scaffold with high affinity for AT-rich DNA duplexes

A dimeric neomycin-neomycin conjugate 3 with a flexible linker, 2,2'-(ethylenedioxy)bis(ethylamine), has been synthesized and characterized. Dimer 3 can selectively bind to AT-rich DNA duplexes with high affinity. Biophysical studies have been performed between 3 and different nucleic acids with varying base composition and conformation by using ITC (isothermal calorimetry), CD (circular dichroism), FID (fluorescent intercalator displacement), and UV (ultraviolet) thermal denaturation experiments. A few conclusions can be drawn from this study: (1) FID assay with 3 and polynucleotides demonstrates the preference of 3 toward AT-rich sequences over GC-rich sequences. (2) FID assay and UV thermal denaturation experiments show that 3 has a higher affinity for the poly(dA)·poly(dT) DNA duplex than for the poly(dA)·2poly(dT) DNA triplex. Contrary to neomycin, 3 destabilizes poly(dA)·2poly(dT) triplex but stabilizes poly(dA)·poly(dT) duplex, suggesting the major groove as the binding site. (3) UV thermal denaturation studies and ITC experiments show that 3 stabilizes continuous AT-tract DNA better than DNA duplexes with alternating AT bases. (4) CD and FID titration studies show a DNA binding site size of 10-12 base pairs/drug, depending upon the structure/sequence of the duplex for AT-rich DNA duplexes. (5) FID and ITC titration between 3 and an intramolecular DNA duplex [d(5'-A(12)-x-T(12)-3'), x = hexaethylene glycol linker] results in a binding stoichiometry of 1:1 with a binding constant ～10(8) M(-1) at 100 mM KCl. (6) FID assay using 3 and 512 hairpin DNA sequences that vary in their AT base content and placement also show a higher binding selectivity of 3 toward continuous AT-rich than toward DNA duplexes with alternate AT base pairs. (7) Salt-dependent studies indicate the formation of three ion pairs during binding of the DNA duplex d[5'-A(12)-x-T(12)-3'] and 3. (8) ITC-derived binding constants between 3 and DNA duplexes have the following order: AT continuous, d[5'-G(3)A(5)T(5)C(3)-3'] > AT alternate, d[5'-G(3)(AT)(5)C(3)-3'] > GC-rich d[5'-A(3)G(5)C(5)T(3)-3']. (9) 3 binds to the AT-tract-containing DNA duplex (B* DNA, d[5'-G(3)A(5)T(5)C(3)-3']) with 1 order of magnitude higher affinity than to a DNA duplex with alternating AT base pairs (B DNA, d[5'-G(3)(AT)(5)C(3)-3']) and with almost 3 orders of magnitude higher affinity than a GC-rich DNA (A-form, d[5'-A(3)G(5)C(5)T(3)-3']).