Nanomaterials for Heterogeneous Combustion

Nanophase materials and nanocomposites, characterized by an ultra fine grain size (less than 100 nm) have attracted wide spread interest in recent years by virtue of their unusual mechanical, electrical, optical, magnetic, and energetic properties. Studies have shown that the thermal behavior of nano‐scaled materials is quite different from micron‐sized powders. Nanosized metallic and explosive powders have been used as solid propellant and explosive mixtures to increase efficiency. At the same time recent studies reveal that the presence of nanosized metals in propellants does not necessary translate into an increased burning rate and burning temperature. The reasons of this effect are far from being clear. This paper presents a new approach to the production of nanocomposites of some energetic materials – ammonium nitrite, cyclotrimethylene trinitramine (RDX), and aluminum – by the vacuum co‐deposition technique. The thermal behavior of the synthesized nanopowder and nanocomposites is investigated. A substantial difference in burning rate of RDX nanopowder has been found in comparison to micron‐sized material. Experimental results allow investigating the effects of nanosized materials on the combustion characteristics.     

Baseline layout and design of a 0.8 GW reference wind farm in the North Sea

The paper presents a model of a reference wind farm. The model considers the wind and wave climatologies for a specific site from which two different wind farm layouts are derived. These layouts are examined through the effective wake‐enhanced turbulence intensity at the hub height for a given climatology, and a simple model for the influence on capital expenditures is proposed. An electrical design is presented, the cable losses are calculated and the energy yield is determined. An operation and maintenance model is established, and the associated operating expenditure is obtained. All of the models are then summarized in terms of a levelized cost of energy using a numerical simulation tool, which allows the layouts to be compared. The data and models are freely available online for others to use and may serve as a baseline for benchmarking and allow researchers to compare and discuss their results. Copyright © 2017 John Wiley & Sons, Ltd.     

Poly(ester amide)s derived from tartaric and succinic acids: Changes in structure and properties upon hydrolytic degradation

The changes in structure and properties taking place in a set of tartaric acid‐based polyamides and poly(ester amide)s upon hydrolytic degradation were examined. Poly(hexamethylene 2,3‐di‐O‐methyl‐L ‐tartaramide)s, either pure or containing minor amounts of succinate ester groups (≤10%), were exposed to humidity or incubated in buffered water at pH 7.4 and 37°C, and their thermal and mechanical properties were evaluated as a function of time. Both moisture uptake and hydrolysis induced a noticeable decay in the tensile properties of polymers. These effects were greatly enhanced by the presence of ester groups, whereas no large differences were noticed for changes in the enantiomeric composition. Variations in the glass transition temperatures and melting points appeared to be slight, whereas crystallinity clearly increased with incubation time. The latter effect was most apparent in poly(ester amide)s with a nearly racemic composition, in which a crystal‐to‐crystal transition was observed to take place upon degradation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 486–494, 2000     

Starch‐capped sulphur nanoparticles synthesised from bulk powder sulphur and their anti‐phytopathogenic activity against Clavibacter sepedonicus

Water‐soluble, stable nanoparticles of elemental sulphur with a size of 9‐52 nm have been synthesised using the stabilising potential of starch. Sulphide anions were used as sulphur precursors that were generated earlier from the bulk powder sulphur in the base‐reduction system NaOH‐N₂H₄·H₂O followed by their oxidation with molecular oxygen to element sulphur atoms. Using a set of modern spectral and microscopic methods (XRD, optical spectroscopy, DLS, TEM), the phase state, elemental composition of the nanocomposites and their nanomorphological characteristics have been investigated. It was found that nanocomposites are formed as sulphur particles with the shape which is nearly spherical dispersed in the polysaccharide starch matrix with a pronounced tendency to cluster into ring formations. Water solubility and stability of the obtained nanoparticles is ensured by sorption of starch macromolecules on the surface of sulphur nanoparticles, with the thickness of the stabilising shell in a range of 10‐171 nm. In vitro experiments were carried out to study the anti‐microbial activity of the obtained sulphur nanocomposite (1.6% S) using the propidium iodide fluorescent dye staining method and the diffusion method. It showed that the water solution of the starch‐capped sulphur nanoparticles at the concentration of 6.25 µg/ml had a pronounced anti‐phytopathogenic activity against the potato ring rot pathogen Clavibacter michiganensis subsp. sepedonicus.     

Evaporation of water from particles in the aerodynamic lens inlet: an experimental study

The extremely high particle transmission efficiency of aerodynamic lens inlets resulted in their wide use in aerosol mass spectrometers. One of the consequences of transporting particles from high ambient pressure into the vacuum is that it is accompanied by a rapid drop in relative humidity (RH). Since many atmospheric particles exist in the form of hygroscopic water droplets, a drop in RH may result in a significant loss of water and even a change in phase. How much water is lost in these inlets is presently unknown. Since water loss can affect particle size, transmission efficiency, ionization probability, and mass spectrum, it is imperative to provide definitive experimental data that can serve to guide the field to a reasonable and uniform sampling approach. In this study, we present the results of a number of highly resolved measurements, conducted under well-defined conditions, of water evaporation from a range of particles, during their transport through an aerodynamic lens inlet. We conclude that the only sure way to avoid ambiguities during measurements of aerodynamic diameter in instruments that utilize low-pressure aerodynamic lens inlets is to dry the particles prior to sampling.     

Correlation of In Vivo and In Vitro Assay Results for Assessment of Free Radical Scavenging Activity of Green Tea Nutraceuticals

Green tea (GT)‐derived catechins; epigallocatechin gallate (EGCG) in particular are commonly used nutraceuticals for their free‐radical scavenging activity (FRSA). The influence of photodegradation on the protective power of GT nutracenticals against oxidative stress was thoroughly explored. Photodegradation of GT extracts was carried out and monitored using orthogonal stability‐indicating testing protocol; in vitro and in vivo assays. Total polyphenol content (TPC) and FRSA were determined spectrophotometrically while EGCG was selectively monitored using SPE‐HPLC. In vivo assessment of photodegraded samples was investigated via measuring a number of biomarkers for hepatic oxidative stress and apoptosis (caspase‐3, inducible nitric oxide synthase, nitric oxide, mitogen‐activated protein kinase, glutathione, thiobarbituric acid reactive substances, nuclear factor kappa beta, and nuclear factor erythroid 2‐related factor) as well as liver damage (alanine transaminase and aspartate transaminase) in serum of rats previously subjected to oxidative stress. Results showed complete degradation of EGCG in photodegraded green tea samples with no correlation with either TPC or FRSA. On the other hand, in vivo assay results revealed not only loss of activity but formation of harmful pro‐oxidants. Photostability was found crucial for the protective effect of GT extract against lead acetate insult. Results confirmed that careful design of quality control protocols requires correlation of chemical assays to bioassays to verify efficacy, stability, and most importantly safety of nutraceuticals.     

Reconstruction of the flotation and filtration department in the coal-enrichment shop at OAO ZSMK

It is established that, at OAO ZSMK, the moisture content in the flotational concentrate is reduced by 4.5% when dehydrating the cake using Andritz vacuum filters rather than Ukraina-80 filters. The content of solid matter in the filtrate is reduced by a factor of four. Extraction of large-grain slurry from the supply to the vacuum filters is more complete, with corresponding reduction in the content of >0.5 mm classes (by 4.1%) and 0.06–0.50 mm classes (by 1.8%) in the filtrate. The loss of final product with the filtrates is reduced by 0.3%; the total power consumption of the vacuum-pump drives is reduced by 826 kW.     

Difluoromethylornithine (DFMO), an Inhibitor of Polyamine Biosynthesis,and Antioxidant N-Acetylcysteine Potentiate Immune Response in Mice to the Recombinant Hepatitis C Virus NS5B Protein

Hepatitis C virus (HCV) is one of the main triggers of chronic liver disease. Despite tremendous progress in the HCV field, there is still no vaccine against this virus. Potential vaccines can be based on its recombinant proteins. To increase the humoral and, especially, cellular immune response to them, more effective adjuvants are needed. Here, we evaluated a panel of compounds as potential adjuvants using the HCV NS5B protein as an immunogen. These compounds included inhibitors of polyamine biosynthesis and urea cycle, the mTOR pathway, antioxidants, and cellular receptors. A pronounced stimulation of cell proliferation and interferon-γ (IFN-γ) secretion in response to concanavalin A was shown for antioxidant N-acetylcysteine (NAC), polyamine biosynthesis inhibitor 2-difluoromethylornithine (DFMO), and TLR9 agonist CpG ODN 1826 (CpG). Their usage during the immunization of mice with the recombinant NS5B protein significantly increased antibody titers, enhanced lymphocyte proliferation and IFN-γ production. NAC and CpG decreased relative Treg numbers; CpG increased the number of myeloid-derived suppressor cells (MDSCs), whereas neither NAC nor DFMO affected MDSC counts. NAC and DFMO suppressed NO and interleukin 10 (IL-10) production by splenocytes, while DFMO increased the levels of IL-12. This is the first evidence of immunomodulatory activity of NAC and DFMO during prophylactic immunization against infectious diseases.     

On the Effect of Particle Alignment in the DMA

The Differential Mobility Analyzer (DMA) is designed to measure particle mobility diameter, which for spherical particles is equal to particle volume equivalent diameter. In contrast, the mobility diameter of aspherical particles is a function of the particle shape and orientation. The magnitude of the DMA electric fields is such that it can cause aspherical particles to align preferentially in a specific orientation. The same electric field and the sheath flow rate ( q _sh ) define the particle mobility diameter. But, the fact that particle orientation depends on the electric field makes the dynamic shape factor and hence the mobility diameter depend on q _sh . Here, we describe an operating procedure that relies on a tandem DMA system, in which the second DMA is operated at a number of q _sh , to obtain information about particle shape by measuring the effect of particle alignment on the particle mobility diameter. We show how the relationship between the mobility diameter and q _sh can even be used to physically separate particles according to their shapes. In addition we explore the use of simultaneous measurements of particle alignment and particle vacuum aerodynamic diameters to gain further information on particle shape and account for particle alignment in the calculations of dynamic shape factor. We first test this approach on doublets and compact triplets of PSL spheres, for which the orientation dependent dynamic shape factors are known. We then investigate applications on a number of polydisperse particle systems of various shapes.