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Topic review
Updated time: 15 Jul 2020
Submitted by: Luigi Monsù Scolaro
Definition: The zinc(II) metal derivative of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4) is quite labile and readily demetallates under acidic conditions, affording the parent diacid porphyrin in a monomeric form. The rate of this process is first order on [ZnTPPS4] and second order on [H+], allowing a precise control of the monomer release in solution. Under high ionic strength, this latter species is able to self-assemble into J-aggregates, whose kinetics of growth are largely modulated by pH. The aggregation kinetics have been treated according to a well-established model, in which the formation of an initial nucleus is the rate determining step preceding the autocatalytic growth of the whole assembly. The extinction spectra of the aggregates suggest the occurrence of a dipolar coupling mechanism very similar to that operating in metal nanoparticles. Spontaneous symmetry breaking takes place in these aggregates as evidenced by unusual circular dichroism spectra. The intensity and sign of the effect is controlled by the aggregation rate and therefore can be tuned through a proper choice of initial conditions.
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Topic review
Updated time: 27 Apr 2021
Submitted by: Łukasz Szeleszczuk
Definition: Molecular dynamics (MD) simulation is a well-established technique used for the study of various chemical substances and mixtures in any state of matter and almost at any temperature and pressure conditions. Its combination with QM NMR calculations can significantly increase the accuracy of the results.
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Biography
Updated time: 28 Oct 2020
Submitted by: Ajaya Bhattarai
Abstract: I am Dr. Ajaya Bhattarai, an Assistant Professor of Chemistry at Tribhuvan University, Nepal. I have received my M.Sc. degree in Physical Chemistry from Tribhuvan University in 1998 and a Ph.D. degree in Polymer Chemistry from North Bengal University, India in 2010. I have also received the "TWAS Young Scientist Award" in 2008 for Chemistry. I have visited the University of Warsaw, Poland for Post-doctorate research in Nanomaterials as well as Surface Chemistry in 2013 under Erasmus Mundus post-doctoral fellowship of European Commission for nine months. I was at Boston College, the USA for Post-doctorate research in “Theoretical studies of Glass-Forming liquids” under Fulbright fellowship for the year 2018-2019. I have published more than 100 articles in reputed journals. My current research interest is in Polymer Chemistry, Surface Chemistry, and Nanomaterials as well as theoretical studies of Glass-Forming liquids.
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Biography
Updated time: 29 Oct 2020
Submitted by: Anan Yaghmur
Abstract: Anan Yaghmur is associate professor at the Department of Pharmacy, Faculty of Health & Medical Sciences, University of Copenhagen. He is also serving as a referee for at least 12 prominent journals including ACS NANO & ACS Applied Materials and Interfaces, Soft Matter, PLoS ONE, PCCP, Chemical Communications, Journal of Physical Chemistry B, and Langmuir. In addition to the evaluation of grant applications for scientific funding bodies. Anan Yaghmur has extensive expertise and know-how in formulation and nanostructural characterization of safe and efficient drug nanocarriers based on self-assembled lyotropic liquid crystalline systems and their dispersions (cubosomes and hexosomes).
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Topic review
Updated time: 09 Apr 2021
Definition: Atmospheric plasma treatment is an effective and economical surface treatment technique. The main advantage of this technique is that the bulk properties of the material remain unchanged while the surface properties and biocompatibility are enhanced.
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Topic review
Updated time: 27 Mar 2021
Submitted by: Bengu Ozturk
Definition: Bioactive lipids, such as fat-soluble vitamins, omega-3 fatty acids, conjugated linoleic acids, carotenoids and phytosterols play an important role in boosting human health and wellbeing. These lipophilic substances cannot be synthesized within the human body, and so people must include them in their diet. There is increasing interest in incorporating these bioactive lipids into functional foods designed to produce certain health benefits, such as anti-inflammatory, antioxidant, anticancer and cholesterol-lowering properties. However, many of these lipids have poor compatibility with food matrices and low bioavailability because of their extremely low water solubility. Nanotechnology is a promising technology that can be used to overcome many of these limitations. Different kinds of nanoscale delivery systems have been designed to encapsulate and protect bioactive lipids, thereby facilitating their handling, stability, food matrix compatibility, and bioavailability.
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Topic review
Updated time: 21 Nov 2020
Submitted by: Valentijn De Coster
Definition: Supported nanoparticles are commonly applied in heterogeneous catalysis. The catalytic performance of these solid catalysts is, for a given support, dependent on the nanoparticle size, shape, and composition, thus necessitating synthesis techniques that allow for preparing these materials with fine control over those properties. Such control can be exploited to deconvolute their effects on the catalyst’s performance, which is the basis for knowledge-driven catalyst design. In this regard, bottom-up synthesis procedures based on colloidal chemistry have proven successful in achieving the desired level of control for a variety of fundamental studies. This article aims to give an overview of recent progress made in this synthesis technique for the application of controlled catalytic materials in gas-phase catalysis. The focus goes to mono- and bimetallic materials, as well as to recent efforts in enhancing their performance by embedding colloidal templates in porous oxide phases.
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Topic review
Updated time: 01 Feb 2021
Submitted by: Junkai Ren
Definition: Carbon Dots (CDs) are a kind of 0-D emissive spheroidal carbon-based nanostructures with a size smaller than 20 nm. The CDs, in fact, stand in between organic (polymers) and inorganic materials (black carbon), macromolecules, and nanoparticle, between bottom-up (polycyclic aromatic compounds) and top-down synthesis (laser ablation of graphene, etc.).
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Topic review
Updated time: 28 Oct 2020
Submitted by: René M. Williams
Definition: We give a systematic overview of compositional engineering by distinguishing the different defect-reducing mechanisms. Doping effects are divided into influences on: (1) crystallization; (2) lattice properties. Incorporation of dopant influences the lattice properties by: (a) lattice strain relaxation; (b) chemical bonding enhancement; (c) band gap tuning. The intrinsic lattice strain in undoped perovskite was shown to induce vacancy formation. The incorporation of smaller ions, such as Cl, F and Cd, increases the energy for vacancy formation. Zn doping is reported to induce strain relaxation but also to enhance the chemical bonding. The combination of computational studies using (DFT) calculations quantifying and qualifying the defect-reducing propensities of different dopants with experimental studies is essential for a deeper understanding and unraveling insights, such as the dynamics of iodine vacancies and the photochemistry of the iodine interstitials, and can eventually lead to a more rational approach in the search for optimal photovoltaic materials.
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Others
Updated time: 30 Oct 2020
Submitted by: Dayane Reis
Abstract: A dinuclear copper(II) complex of (1) (where bipy = 2,2′‑bipyridine, bzt = benzoate and ox = oxalate) was synthesised and characterised by diffractometric (powder and single-crystal XRD) and thermogravimetric (TG/DTG) analyses, spectroscopic techniques (IR, Raman, electron paramagnetic resonance spectroscopy (EPR) and electronic spectroscopy), magnetic measurements and density functional theory (DFT) calculations. The analysis of the crystal structure revealed that the oxalate ligand is in bis(bidentate) coordination mode between two copper(II) centres. The other four positions of the coordination environment of the copper(II) ion are occupied by one water molecule, a bidentate bipy and a monodentate bzt ligand. An inversion centre located on the ox ligand generates the other half of the dinuclear complex. Intermolecular hydrogen bonds and pi-pi for the organisation of the molecules in the solid state. Molar magnetic susceptibility and field dependence magnetisation studies evidenced a weak intramolecular–ferromagnetic interaction (J = +2.9 cm‑1) between the metal ions. The sign and magnitude of the calculated J value by density functional theory (DFT) are in agreement with the experimental data.
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