Ignition Wave in a Two–Velocity Gas Mixture of Magnesium Particles

The theory of a steady ignition wave in a multicomponent mixture of a gas and magnesium particles, which is nonequilibrium in terms of phase velocities, is developed. Conditions where the action of a shock wave on a cloud of particles leads to their ignition or regular heating are determined. Qualitatively different types of behavior of the temperatures of dispersed and gas phases behind the front of the leading shock wave are found. A significant role of interphase friction at the early stages of development of the thermal explosion is demonstrated. Verification of the model is performed on the basis of experimental data on the dependence of the induction period of the oxidation reaction in the cloud of particles on the shock–wave Mach number. It is shown that the numerical data obtained within the framework of the equilibrium and nonequilibrium (in terms of phase velocities) models are in good agreement for small–size particles.     

Effect of Molecular Additives on the Ignition of Methane–Air Mixtures

Combustion, Explosion, and Shock Waves - The ignition of methane–air mixtures with additives of ClF5, ClF3, OF2, and H2O2 (additive content in the mixtures  $$\le$$ 1%) is studied by...     

Comment on “Degradation of Two Persistent Surfactants by UV-Enhanced Ozonation”

In a recent issue of this journal, Tehrani-Bagha et al. (J Surf Deterg 15:59?C66, 2012) state that sodium dodecylbenzene sulfonate, more commonly known as linear alkylbenzene sulfonate (LAS) is a ??persistent surfactant?? that demonstrates ??low biodegradability.?? Tehrani-Bagha et al. further imply that LAS has ??harmful effects?? on the environment, causing ??serious environmental pollution.?? This comment reviews some of the extensive literature available on LAS including five environmental assessments which concluded that LAS is of low concern and not a risk to the environment. Published studies and reviews report that LAS passes stringent laboratory tests designed to measure ready biodegradability and demonstrates rapid biodegradation in both laboratory and field studies. These studies and assessments contradict the statements made about LAS in the Tehrani-Bagha et al. paper.     

Special Issue on “Two Dimensional Materials”

<正>1.Summary and Scope Research on two dimensional(2D)materials,one of the most extensively studied classes of materials(especially graphene),hasgrown rapidly over the past several years and attracted great attention of thousands of scientists from across physics,chemistry,engineering,medicine and industry.This research activity has triggered the emergence of a new generation of atomically thin metals,semimetals,semiconductors,nitrides,oxides/hydroxides,transition metal dichalcogenides,topological insulators and even polymers,demonstrating the potential for novel properties and technological innovations.     

Ignition of droplets of coal–water–oil mixtures based on coke and semicoke

To permit expansion of the resource base and utilize industrial waste, coal–water–oil fuels may be prepared on the basis of coke and semicoke, as well as common petroleum derivatives (fuel oil and spent compressor, turbine, and transformer oils). The minimal oxidant temperature corresponding to stable ignition of coal–water–oil slurries is established. Typical variation in fuel temperature in the course of reaction is determined, as well as the delay time of ignition and the total combustion time for individual droplets of such fuel suspensions. For droplets of initial size 0.5–1.5 mm, the influence of the various factors (droplet size, oxidant temperature, and concentration of the components) on the threshold (minimum) temperature and inertia of ignition is studied. It is shown that stable ignition of coke and semicoke in such fuel is possible at moderate oxidant temperatures: 700–1000 K.     

Effect of Radiant Heat Transfer on the Minimum Spark–Ignition Energy of Gas Suspensions

A mathematical model of spark ignition of a gas suspension is constructed on the basis of a two–temperature thermal diffusion model of gas–suspension combustion and the radiant heat transfer is modeled in a diffusion approximation. The dependences of the minimum ignition energy on the parameters which describe the disperse phase and the domain of the disperse–phase parameters in which the radiant heat transfer affects greatly the minimum spark–ignition energy is determined by solving the problem numerically. The analytical formula that was obtained for determination of the critical spark–ignition energy of the gas suspension and that takes into account the radiant heat transfer in the gas suspension gives values different from numerical results by not more than 30% in a broad range of determining parameters of the problem. The theoretically obtained values of the minimum spark–ignition energy of a gas suspension of coal dust agree satisfactorily with experimental data.     

Initiation of Ignition by the Action of a High‐Current Pulsed Discharge on a Gas

The possibility of nonthermal initiation of chemical reactions by a uniform pulsed nanosecond discharge is demonstrated. Dependences of variation of the ignition delay on initial conditions are obtained. It is shown that the main role in combustion initiation under conditions of a pulsed gas discharge in the case of moderate electric fields and low degree of ionization belongs to reactions of dissociation quenching of electronexcited levels of nitrogen.     

Effect of Diffusion of Coal Pyrolysis Products on the Ignition Characteristics and Conditions of Coal–Water Fuel Droplets

This paper presents a theoretical study of the thermal preparation and ignition of a coal–water fuel droplet under intense radiative-convective heating with diffusion of gaseous pyrolysis products of the solid fuel into the ambient gaseous medium. It has been found that gaseous pyrolysis products are ignited at a distance from the heating surface approximately equal to the radius of the droplet, after which the coke of the main fuel layer is ignited. The time between the ignition of volatiles and the coke residue is less than 0.5 s. Comparison of the ignition delays obtained by mathematical modeling and experimentally has shown satisfactory agreement between theoretical and experimental values.     

Separate versus Simultaneous Saccharification and Fermentation of Two‐Step Steam Pretreated Softwood for Ethanol Production

Abstract

In two previous studies, optimal conditions were identified for two‐step steam pretreatment of SO₂‐ and H₂SO₄‐impregnated softwood. In the present study the yield of sugar and ethanol was determined in a process development unit where pretreatment was performed in a 10‐L reactor and simultaneous saccharification and fermentation (SSF) or enzymatic hydrolysis (EH) were performed in 30‐L reactors. The study showed that a steam pretreatment reactor should be larger than 2 L to yield acceptable results. Two pretreatment combinations were studied. In the H₂SO₄ case, the first pretreatment step was at 180°C for 10 min with 0.5% H₂SO₄ and the second step at 210°C for 2 min with 1% H₂SO₄. In the SO₂ case, first step was at 190°C for 2 min followed by a second step at 210°C for 5 min. The concentration of SO₂ was 3% in both steps. EH and SSF were performed on the whole slurry after the second pretreatment step to determine the yield of sugars and ethanol. The liquid after the first pretreatment step was also analyzed and fermented. When SSF and EH were performed at the same dry matter content and enzymatic activity, the ethanol yield in SSF exceeded the yield obtained with EH in both pretreatment cases, even when 100% yield in the fermentation step was assumed. Thus SSF is a better process if yield is the main priority. Comparison of the yields with the two acid catalysts showed higher yields with SO₂ in both SSF and EH. The overall ethanol yield following SSF of SO₂‐impregnated and pretreated wood reached 81% of the theoretical, that is, 357 liters per metric ton of dry raw material.     

Influence Parameters on Properties of Dolomite Bricks Containing Different Bonding Systems

Pitch and tar bonded dolomite bricks are extensively used in ladles and converters for long time because of their superior properties such as. steel melt refining, easy production as well as low production cost. Recently, resin bonded dolomite bricks are presented for using in steel plants. Generally, quality and final cost of steels are affected by properties of refractories especially dolomite bricks. Therefore, recognition of influence parameters on dolomite refractory properties is very important. In this study, the effects of tar and resin as bonding systems, and addition of graphite （ 2wt% ） on the properties of dolomite refractory bricks have been investigated. Properties such as ： density and porosity, cold crushing strength, hydration time and depth of slag penetration have been studied. Results show that the bonding sys- tems and graphite have a great effect on the mentioned properties especially cold crushing strength and hydra- tion time. In addition to their low rate of pollution, resin bonded dolomite bricks show higher performance with proper technical specifications.     

The Effect of Olive Leaf Addition on Antioxidant Content and Antioxidant Activity of “Memecik” Olive Oils at Two Maturity Stages

In this study, the effects of leaf addition, maturity stage and storage on the antioxidant content and activity of olive oils (cv. Memecik) were investigated in the 2008/09 and 2009/10 crop seasons. Olive fruits were harvested at two different maturity stages (early and late), and the leaves of the same cultivar were added at different rates (0, 1, and 3 %) prior to oil extraction. After extraction, the oil samples were stored for 18 months and total chlorophyll, α-tocopherol, total phenolic content and the antioxidant activity [DPPH^· (2,2-diphenyl-1-picrylhydrazyl) and ABTS^·+ (2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid) radical scavenging] were determined at 6 month-intervals. Olive leaf addition induced a significant increase in total chlorophyll, α-tocopherol, total phenolic content, and antioxidant activities in both years (P < 0.001). During the storage period antioxidant content and antioxidant activities in the oils significantly decreased in both years (P < 0.001). However, the oils to which leaf material was added had higher antioxidant contents and activities than those without leaf material addition at the end of the 18-month storage period. After storage, the antioxidant content and DPPH^· radical scavenging activity of control (0 %) samples were lower than those in the leaf added samples (3 %). The data obtained from this study suggested that the addition of olive leaf to oils allowed more functional olive oils with higher antioxidant contents.     

Two–Dimensional Stability of the “Pole” Solutions of the Sivashinsky Equation

The two–dimensional stability of the exact solution of the Sivashinsky equation governing the evolution of a curved flame surface in the hydrodynamic approximation is studied. It is shown that the one–dimensional pole solution of this equation governing a local minimum of the surface is stable with respect to small two–dimensional perturbations. The problem is solved under the assumption that the perturbations are small at a distance from the local minimum. Stable one–dimensional solutions may be used to verify numerical simulation of the surface of a hydrodynamically unstable flame and also to construct two–dimensional solutions of the Sivashinsky equation.     

Two Different Approaches for Oral Administration of Voriconazole Loaded Formulations: Electrospun Fibers versus β-Cyclodextrin Complexes

In this work, a comparison between two different preparation methods for the improvement of dissolution rate of an antifungal agent is presented. Poly(ε-caprolactone) (PCL) electrospun fibers and β-cyclodextrin (β-CD) complexes, which were produced via an electrospinning process and an inclusion complexation method, respectively, were addressed for the treatment of fungal infections. Voriconazole (VRCZ) drug was selected as a model drug. PCL nanofibers were characterized on the basis of morphology while phase solubility studies for β-CDs complexes were performed. Various concentrations (5, 10, 15 and 20 wt %) of VRCZ were loaded to PCL fibers and β-CD inclusions to study the in vitro release profile as well as in vitro antifungal activity. The results clearly indicated that all formulations showed an improved VRCZ solubility and can inhibit fungi proliferation.     

Efficacy and Mechanisms of α-Solasonine-and α-Solamargine-Induced Cytolysis on Two Strains of Trypanosoma cruzi

Two genetically diverse strains of Trypanosoma cruzi were tested in vitro for susceptibility to the solanum-derived triglycoside alkaloids solasonine and solamargine. Cytolytic assays were performed on epimastigotes (EMs) and bloodstream form trypomastigotes (BSFs) lifecycle stages by using serial dilutions of each alkaloid. Each alkaloid effectively lysed both lifecycle stages, although solasonine routinely required higher concentrations to induce similar results. EMs demonstrated greater resistance to cytolysis than BSFs at equal concentrations of either alkaloid. No significant resistance could be correlated to parasite strain. The reported synergistic cytolytic effects observed upon compounding solasonine and solamargine together were also tested. We failed to identify any cytolytic synergism in cultures of EMs or BSFs. The role of rhamnose-binding proteins (RBPs) in mediating cytolysis was investigated through competitive inhibition experiments. The addition of exogenous l-rhamnose to the media failed to reduce parasite attrition independent of the parasite lifecycle stage. Based on these results, we suggest the mechanisms involved in cytolysis of T. cruzi by solasonine and solamargine are largely independent of rhamnose receptor-specific interactions. We propose that attrition likely involves less-specific carbohydrate interactions, which lead to the formation and intercalation of sterol complexes into the parasite plasma membrane.     

Aerosolization of Two Strains (Ice+ and Ice–) of Pseudomonas syringae in a Collison Nebulizer at Different Temperatures

The aerosolization of microorganisms from aquatic environments is understudied. This article describes a study in which an ice nucleation active (ice+) strain and a nonice nucleation active (ice?) strain of the bacterium Pseudomonas syringae were aerosolized from aqueous suspensions under artificial laboratory conditions using a collison nebulizer. The aerosolization of P. syringae was not influenced by water temperatures between 5° and 30°C. In general, the culturability (viability) of P. syringae in aerosols increased with temperature between 5 and 30°C. The ice+ strain was aerosolized in greater numbers than the ice– strain at all temperatures studied, suggesting a possible connection between the ice nucleation phenotype and aerosol production. Together, our results suggest that P. syringae has the potential to be aerosolized from natural aquatic environments, such as streams, rivers, ponds, and lakes; known reservoirs of P. syringae. Future work is needed to elucidate the mechanisms of aerosolization of P. syringae from natural aquatic systems.

Copyright 2015 American Association for Aerosol Research     

Sulfonamide Inhibitors of β-Catenin Signaling as Anticancer Agents with Different Output on c-MYC

The Wnt/β-catenin pathway is often found deregulated in cancer. The aberrant accumulation of β-catenin in the cell nucleus results in the development of various malignancies. Specific drugs against this signaling pathway for clinical treatments have not been approved yet. Herein we report inhibitors of β-catenin signaling of potential therapeutic value as anticancer agents. Ethyl 4-((4-(trifluoromethyl)phenyl)sulfonamido)benzoate (compound 14 ) inhibits the effect on Wnt reporter with an IC₅₀ value of 7.0 μM, significantly reduces c-MYC levels, inhibits HCT116 colon cancer cell growth (IC₅₀ 20.2 μM), does not violate Lipinski and Veber rules, and shows predicted Caco-2 and MDCK cell permeability P_app>500 nm s⁻¹. Compound 14 seems to have potential for the development of new anticancer therapies.     

Effective Collection of Airborne Micro-Organisms by Direct Impaction on Silicone Sealants—Comparison of Different Adherent Surfaces

For effective sampling of airborne micro-organisms different techniques such as impingement, filtration and impaction are commonly used. Impaction is the method which allows best for direct collection on adhesive surfaces for immediate microscopic analysis. The efficiency of collection largely depends on the quality of the sampling surface to retain particles. This article compares the suitability of some traditional and new adhesive coatings to collect and retain airborne micro-organisms efficiently for subsequent fluorescence microscopy. Sacharomyces cerevisiae yeast cells were aerosolized in a test tubing system in the laboratory. Samples were collected by a round jet impactor in a defined round deposition area on glass slides coated with different adhesive materials. Particle distribution in the deposition area and collection efficiency as well as particle losses were estimated. Fluorescent staining with Mycoval and DAPI was used to quantify the amount of collected cells and cell losses due to the staining procedure. Filtration was taken as reference system. The collection efficiency of the tested adhesive surfaces ranged from 2 to 97%. Silicone sealants showed with 97% the highest collection efficiency. All particles were located in the central region of the deposition area. Cell losses due to the staining procedure were very small (<1%) and no background fluorescence was observed after DAPI staining. Even after sampling times of 45 min the collection efficiency was still above 90%. Longer collection (>50 min) resulted in increasing cell losses. Collection efficiency was little influenced by relative humidity of the air between 20% and 100%.     

Effects of Different Carbon Sources and NaBr- KCl on Synthesis of Ti（C, N）

Ti(C,N)was synthesized with the starting materials of 76.9% titania white and 23.1% carbon black(graphite or activated carbon),or 40% titania white and 60% amylum,with or without 10% NaBr-KCl,dry moulding and carbon embedded firing at 1 300 ℃ and 1 400 ℃ for 3 h,respectively.Phase composition and microstructure of the synthesized Ti(C,N)were analyzed by XRD,SEM and EPMA.Effects of different carbon sources and NaBr-KCl on the synthesis of Ti(C,N)were investigated.The results show that:(1)Ti(C,N)can be synthe...