V. A. Vinokurov

Pd Nanoparticles in Dendrimers Immobilized on Silica–Polyamine Composites as Catalysts for Selective Hydrogenation

New heterogeneous hydrogenation catalysts, based on Pd nanoparticles and polypropyleneimine (PPI) dendrimers of the third generation that have been covalently grafted to a silica surface modified with polyallylamine (PAA) have been synthesized. The final products were characterized by TEM, XPS, and solid-state NMR spectroscopy. The synthesized materials are effective catalysts for selective hydrogenation of dienes to monoenes and phenyl acetylene to styrene at very high substrate/Pd ratios with turnover rates higher than related Pd nanoparticle catalysts. The synthesized catalysts can be reused without any loss of activity in the case of styrene and isoprene.

Formation of metal clusters in halloysite clay nanotubes

Abstract We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of c.50 nm, a lumen of 15 nm and length ~1 μm. This allowed for synthesis of metal nanoparticles at the selected position: (1) on the outer surface seeding 3–5 nm metal particles on the tubes; (2) inside the tube’s central lumen resulting in 10–12 nm diameter metal cores shelled with ceramic wall; and (3) smaller metal nanoparticles intercalated in the tube’s wall allowing up to 9 wt% of Ru, and Ag loading. These composite materials have high surface area providing a good support for catalytic nanoparticles, and can also be used for sorption of metal ions from aqueous solutions.

Application of halloysite clay nanotubes as a pharmaceutical excipient

Halloysite nanotubes, a biocompatible nanomaterial of 50-60nm diameter and ca. 15nm lumen, can be used for loading, storage and sustained release of drugs either in its pristine form or with additional polymer complexation for extended release time. This study reports the development composite tablets based on 50wt.% of the drug loaded halloysite mixed with 45wt.% of microcrystalline cellulose. Powder flow and compressibility properties of halloysite (angle of repose, Carrs index, Hausner ratio, Brittle Fracture Index, tensile strength) indicate that halloysite is an excellent tablet excipient. Halloysite tubes can also be filled with nifedipine with ca. 6wt.% loading efficiency and sustained release from the nanotubes. Tablets prepared with drug loaded halloysite allowed for almost zero order nifedipine release for up to 20h. Nifedipine trapped in the nanotubes also protect the drug against light and significantly increased the photostability of the drug. All of these demonstrate that halloysite has the potential to be an excellent pharmaceutical excipient that is also an inexpensive, natural and abundantly available material.

Spectroscopy of Scattered Light for the Characterization of Micro and Nanoscale Objects in Biology and Medicine

The biomedical uses for the spectroscopy of scattered light by micro and nanoscale objects can broadly be classified into two areas. The first, often called light scattering spectroscopy (LSS), deals with light scattered by dielectric particles, such as cellular and sub-cellular organelles, and is employed to measure their size or other physical characteristics. Examples include the use of LSS to measure the size distributions of nuclei or mitochondria. The native contrast that is achieved with LSS can serve as a non-invasive diagnostic and scientific tool. The other area for the use of the spectroscopy of scattered light in biology and medicine involves using conducting metal nanoparticles to obtain either contrast or electric field enhancement through the effect of the surface plasmon resonance (SPR). Gold and silver metal nanoparticles are non-toxic, they do not photobleach, are relatively inexpensive, are wavelength-tunable, and can be labeled with antibodies. This makes them very promising candidates for spectrally encoded molecular imaging. Metal nanoparticles can also serve as electric field enhancers of Raman signals. Surface enhanced Raman spectroscopy (SERS) is a powerful method for detecting and identifying molecules down to single molecule concentrations. In this review, we will concentrate on the common physical principles, which allow one to understand these apparently different areas using similar physical and mathematical approaches. We will also describe the major advancements in each of these areas, as well as some of the exciting recent developments.

Rapid optimization of metal nanoparticle surface modification with high-throughput gel electrophoresis.

The ability to effectively control and optimize surface modification of metal nanoparticles is paramount to the ability to employ metal nanoparticles as diagnostic and therapeutic agents in biology and medicine. Here we present a high-throughput two-dimensional-grid gel electrophoresis cell (2D-GEC)-based method, capable of optimizing the surface modification of as many as 96 samples of metal nanoparticles in approximately 1 h. The 2D-GEC method determines not only the average zeta-potential of the modified particles but also the homogeneity of the surface modification by measuring the distance between the front of the sample track and the area where the maximum optical density is achieved. The method was tested for optimizing pH and concentration of the modifiers (pM) for functionalizing gold nanorod thiol-containing acidic agents.

Ultrashort laser pulse-induced anti-Stokes photoluminescence of hot electrons in gold nanorods

We report observing anti-Stokes broadband radiation induced in gold nanorods by ultrashort laser pulses. The radiation is in the visible spectral range along with the second harmonic peak. Unlike conventional photoluminescence of metal nanoparticles, the energy of the excitation photons is smaller than the gap between the top of the d band and the Fermi level. Because the gold nanorods are irradiated with a pulse whose time is shorter than the electron–phonon equilibration time in gold, the energy is absorbed by s/p band electrons, creating a temperature difference between the electrons and the lattice, as described by the two-temperature model. Therefore, we identify the origin of the observed radiation as the recombination of hot conduction electrons with the d band holes created by the same ultrashort laser pulse.

Hydrogenation of aromatic hydrocarbons over nickel–tungsten sulfide catalysts containing mesoporous aluminosilicates of different nature

The hydrogenation of naphthalene, toluene, and 2-methylnaphthalene used as model compounds; the hydrodearomatization of the methylnaphthalene fraction; and the hydrocracking of oil sludge over Ni–W sulfide catalysts supported on BEA/TUD, BEA/SBA-15, and ZSM-5/SBA-15 composites containing SBA-15 and TUD mesoporous silicates have been studied. Catalytic tests have been conducted in an autoclave at 300–400°C and an initial hydrogen pressure of 50–90 atm. It has been found that the highest activity is exhibited by the catalyst based on the ZSM-5/SBA-15 (1) composite prepared by the double-templating synthesis and characterized by a specific surface area of 400 m2/g and an acidity of 409 μmol/g. Thus, in the case of dearomatization of the methylnaphthalene fraction at 300°C and an H2 pressure of 50 atm, the content of diaromatic compounds has decreased from 99.0 to 53.4%, while the amount of sulfur compounds has decreased almost 15-fold. The hydrocracking of oil sludge over NiW/ZSM-5/SBA-15 (2) at 400°C and an H2 pressure of 90 atm has led to an increase in the content of light fractions to 52%.

New strains of basidiomycetes that produce bioethanol from lignocellulose biomass

Sixty six isolates were screened for ability of bioethanol production; dynamics of product accumulation and substrate utilization were investigated for two selected strains Trametes hirsuta MT-24.24 and Trametes versicolor IT-1. The strains’ efficiency was evaluated as bioethanol production by 1 g biomass. Strain T. versicolor IT-1 producing over 33 g/L of the ethanol for 9 d was selected. Direct conversion of Na-carboxymethyl cellulose, microcrystalline cellulose and straw was shown with ethanol yields of 2.1, 1.6 and 1.7 g/L, respectively, for 9 d fermentation time.

Oil Sludge Treatment Processes

This review considers effective modern methods for oil sludge and acid resid treatment. We analyze in detail the technologies for dewatering, solidification, solvent extraction, thermal treatment (including in the presence of catalysts), and modern oil sludge and solid fuel (oil shales, coals) treatment methods. We note that the dominant criteria for the effectiveness of oil waste utilization technology should be cost effectiveness and reduced environmental stress.

Ethanol Production from Lignocellulosic Biomass Using Xylotrophic Basidiomycetes

The scientific literature on the use of xylotrophic basidial fungi for pretreatment, hydrolysis, and fermentation of lignocellulosic biomass was reviewed. The influence of cultivation conditions on the treatment effectiveness was studied. The major deficiencies of consolidated bioprocessing of plant materials into ethanol using basidiomycetes were the low final ethanol concentration and the long pretreatment time.