There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Intermolecular And Surface Forces

2005년 대한 생화학·분자생물학회 하계학술대회를 다녀와서

Carbonaceous nanomaterials for the enhancement of TiO2 photocatalysis

Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr3C2, CrN, VC(N), VN, TiC, TiC(N), TiN, and V2O3 all showed excellent catalytic activity for the reduction of I3– to I– in the electrolyte. Further, VC embedded in mesoporous carbon (VC–MC) was prepared through in situ synthesis. The I3–/I– DSC based on the VC–MC CE reached a high power conversion efficiency (PCE) of 7.63%, comparable to the photovoltaic performance of the DSC using a Pt CE (7.50%). In addition, the carbide catalysts demonstrated catalytic activity higher than that of Pt for the regeneration of a new organic redox couple of T2/T–. The T2/T– DSCs using TiC and VC–MC CEs showed PCEs of 4.96 and 5.15%, much higher than that of the DSC using a Pt CE (3.66%). This work expands the list of potential CE catalysts, which can help reduce the cost of DSCs and thereby...

Economical Pt-Free Catalysts for Counter Electrodes of Dye-Sensitized Solar Cells

Amphiphiles are synthetic or natural molecules with the ability to self-assemble into a wide variety of structures including micelles, vesicles, nanotubes, nanofibers, and lamellae. Self-assembly processes of amphiphiles have been widely used to mimic biological systems, such as assembly of lipids and proteins, while their integrated actions allow the performance of highly specific cellular functions which has paved a way for bottom-up bionanotechnology. While amphiphiles self-assembly has attracted considerable attention for decades due to their extensive applications in material science, drug and gene delivery, recent developments in nanoscience stimulated the combination of the simple approaches of amphiphile assembly with the advanced concept of supramolecular self-assembly for the development of more complex, hierarchical nanostructures. Introduction of stimulus responsive supramolecular amphiphile assembly-disassembly processes provides particularly novel approaches for impacting bionanotechnology applications. Leading examples of these novel self-assembly processes can be found, in fact, in biosystems where assemblies of different amphiphilic macrocomponents and their integrated actions allow the performance of highly specific biological functions. In this perspective, we summarize in this tutorial review the basic concept and recent research on self-assembly of traditional amphiphilic molecules (such as surfactants, amphiphile-like polymers, or lipids) and more recent concepts of supramolecular amphiphiles assembly which have become increasingly important in emerging nanotechnology.

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Amphiphiles Self-Assembly: Basic Concepts and Future Perspectives of Supramolecular Approaches

Study of the growth of ZnS nanoparticles in water/AOT/n-heptane microemulsions by UV-absorption spectroscopy

Here we report on the fabrication of a new low-cost transparent cathode based on platinum nanoparticles prepared by a bottom-up synthetic approach. Scanning Electron Microscope (SEM) images showed the platinum nanoparticles homogeneously distributed on a fluorine doped tin oxide conductive glass surface. We demonstrated that, with such a type of cathode, the solar energy conversion efficiency is the same as that obtained with a platinum sputtered counter-electrode, and is more than 50% greater than that obtained with a standard electrode, i.e. one prepared by chlorine platinum acid thermal decomposition, in similar working conditions. Using a special back-reflecting layer of silver, we improved upon the performance of a counter-electrode based on platinum sputtering, achieving an overall solar conversion efficiency of 4.75% at 100 mW cm−2 (AM 1.5) of simulated sunlight.

A new type of transparent and low cost counter-electrode based on platinum nanoparticles for dye-sensitized solar cells

The development of smart nanocarriers for the delivery of therapeutic drugs has experienced considerable expansion in recent decades, with the development of new medicines devoted to cancer treatment. In this respect a wide range of strategies can be developed by employing liposome nanocarriers with desired physico-chemical properties that, by exploiting a combination of a number of suitable soft interactions, can facilitate the transit through the biological barriers from the point of administration up to the site of drug action. As a result, the materials engineer has generated through the bottom up approach a variety of supramolecular nanocarriers for the encapsulation and controlled delivery of therapeutics which have revealed beneficial developments for stabilizing drug compounds, overcoming impediments to cellular and tissue uptake, and improving biodistribution of therapeutic compounds to target sites. Herein we present recent advances in liposome drug delivery by analyzing the main structural features of liposome nanocarriers which strongly influence their interaction in solution. More specifically, we will focus on the analysis of the relevant soft interactions involved in drug delivery processes which are responsible of main behaviour of soft nanocarriers in complex physiological fluids. Investigation of the interaction between liposomes at the molecular level can be considered an important platform for the modeling of the molecular recognition processes occurring between cells. Some relevant strategies to overcome the biological barriers during the drug delivery of the nanocarriers are presented which outline the main structure-properties relationships as well as their advantages (and drawbacks) in therapeutic and biomedical applications.

Soft Interaction in Liposome Nanocarriers for Therapeutic Drug Delivery.

Ultra-small ZnS nanoparticles have been synthesized by a novel solid−solid reaction between Na2S and ZnSO4 nanoparticles in the confined space of AOT reversed micelles. The reaction was performed by mixing two dry AOT/n-heptane solutions, containing Na2S and ZnSO4 nanoparticles, respectively. This synthetic route has been revealed to have specific advantages giving anhydrous systems with high nanoparticle concentration. From these systems, by simple evaporation of the organic solvent, interesting AOT/ZnS composites can be prepared. Size, polydispersity, and photophysical properties of AOT reversed micelles containing ZnS nanoparticles dispersed in n-heptane have been investigated as function of salt and AOT concentrations by SAXS and UV spectroscopy. The UV spectra of all samples, including AOT/ZnS composites, showed a red shift of the first excitonic transition band with time but, as assured by SAXS experiments performed on liquid samples, this phenomenon was not associated with any change in mean size a...

Pietro Calandra

Papers

Amphiphiles Self-Assembly: Basic Concepts and Future Perspectives of Supramolecular Approaches

Study of the growth of ZnS nanoparticles in water/AOT/n-heptane microemulsions by UV-absorption spectroscopy

A new type of transparent and low cost counter-electrode based on platinum nanoparticles for dye-sensitized solar cells

Soft Interaction in Liposome Nanocarriers for Therapeutic Drug Delivery.

Synthesis of Ultra-small ZnS Nanoparticles by Solid−Solid Reaction in the Confined Space of AOT Reversed Micelles